For a Healthier 2018!

Dancing together is good for your health!

 

By Jesica Levingston Mac leod, PhD

 

Social dancers know the amazing feeling that a synchronized dance could bring. When your follower or leader is connected and it feels like you are one mind and body following the music, it is mystical and magical… Well, it turns out that synchronized dancing is also good for your health. I started dancing salsa because a good friend was going crazy about it and she recommended it, this inspired me to join a class. At this point I was a solitary belly dancer only following in team dances where you have choreography and if you are coordinated enough you feel this celestial connection with the other dancers…but without any physical contact.

On the other hand, in social dances like salsa, bachata, tango, zouk or swing, the connection is the base of a good dance. Nobody wants to be the person stepping to the left when 5 other dancers moved to the right while performing in a stage in front of hundreds of people, as well as nobody enjoys turning to the wrong side for misreading your dance partner lead, or watching how a follower does a completely different step that the one the leader indicated. Furthermore, being “in sync” with the group or your direct dance partner may help to improve your health, science says. In a nutshell, a recent study found that synchronizing with others while dancing raised pain tolerance and encouraged people to feel closer to others.

This year, Dr. Burzynska et al., at Colorado State University, separated 174 healthy adults, 60s to 79 years old, who had no signs of memory loss or impairment, into 3 activity groups: walking, stretching and balance training, or dance classes. The activities were carry on for 6 months and three times a week, those in the dance group practiced and learned a country dance choreography. Brain scans were done on all participants and compared with scans taken before the activities began. Not surprisingly, the participants in the dancing group performed better and had less deterioration in their brains than the other groups. Their most recent study published in November: “The Dancing Brain: Structural and Functional Signatures of Expert Dance Training” showed that dancers’ brains differed from non-dancers’ at both functional- and structural-levels. Most of the group differences were skill-relevant and correlated with objective laboratory measures of dance skill and balance. Their results are promising in that long-term, versatile, combined motor and coordination training may induce neural alterations that support performance demands.” (link 2)

Moreover, It is well established that dancing-based therapies are providing outstanding results in the treatment of dementia, autism and Parkinson’s. Indeed, dance therapy improves motor and cognitive functions in patients with Parkinson’s disease. Dancing was suggested to be a powerful tool to improve motor-cognitive dual-task performance in adults. Dance movement therapy has known benefits for cancer patients’ physical and psychological health and quality of lifeAnother study by Domane and collaborators, working with a cohort of overweight and physically inactive women, showed that Zumba fitness is indeed an efficacious health-enhancing activity for adults. Park also concluded that “a 12-week low- to moderate-intensity exercise program appears to be beneficial for obese elderly women by improving risk factors for cardiovascular disease”.

Dancing helps generate positive connections with others and this is one of the evolutionary reasons you are “called” to the dance floor when a song you like starts playing, and probably you will start your dance by coordinating with or copying others. Probably this behavior signaled tribe membership for early humans and also got couples together in a more romantic way, creating emotional bonds. Coordinated dances are as old as music, and distributed in a lot of different cultures, for example, the nowadays Hakka, used by rugby players, was a native group dance that intimidates rival tribes.

Talking about the chemistry of dancing, as any other exercise, it releases endorphins (the hormones of happiness and pain relief). For example, a study from the University of London were anxiety-sufferers enrolled in one of four settings: exercise class, a music class, a math class and a dance class, showed that only the last group displayed “significantly reduced anxiety.”

In the most recent study done in the same London University by Tarr and collaborators, the researchers used pain thresholds as an indirect measure of endorphin realize (more endorphins mean we tolerate pain better) for 264 young people in Brazil. The volunteers were divided into groups of three, and they did either high or low-exertion dancing that was either synchronized or unsynchronized. The high exertion moves were standing, full-bodied movements, on the other hand, in the low-exertion groups did small hand movements sitting down. They measured the before and after feelings of closeness to each other via a questionnaire and their pain threshold by attaching and inflating a blood pressure cuff on their arm, and determining how much pressure they could stand.

Most of the volunteers who did full-bodied exertive dancing had higher pain thresholds compared with those who were in the low-exertion groups. Most importantly, synchronization led to higher pain thresholds, even if the synchronized movements were not exertive. Therefore when the volunteers saw that others were doing the equivalent movement at the same time, their pain thresholds increased.

The results also showed that synchronized activity encouraged bonding and closeness feelings more than unsynchronized dancing. Therefore, “Dance which combined high energy and synchrony had the greatest effects. So the next time you find yourself in an awkward Christmas party or at a wedding wondering whether or not to get up and groove, just do it”, claims Dr. Tarr.

Coming back to the dance floor, I had reached out for an opinion about the wellness of dancing to the best Bachata DJ: Brian el Matatan: “I enjoy the dancing for a few reasons. There’s the enjoyment & challenge of using what I’ve learned; socially as well as choreographed performance. Also, there is the rush of endorphins similar to “runner’s high”. There’s also the socializing aspect of dancing. It’s like having a conversation without speaking.” Well said DJ!
He also offered some advice for followers: dance with many different types of leaders if you’d like to improve your following. There are many different leads, and there is an experience to be gained in social dancing that would not be gained via dance class. Also, feel free to ask a leader to dance, & be courteous in how you decline a dance. Most importantly- communicate. Don’t “lead” a leader into thinking their lead is better than what it really is- for your sake & that of your fellow followers. For example, if he almost ended your life with that risky move, let him know so that he doesn’t try it on you or anyone else again (at least not without figuring out how to do the move properly). And some advice for leaders: be VERY  courteous in how you ask for a dance, try to not take rejection personally, be patient with follows who may not be on the same skill level as you, & don’t almost end her life with risky moves.

Lastly, I asked for the most sensual dancer, scientist, and project manager –  Debbie McCabe – for her advice for followers. She commented “The lady’s job is to surrender and connect to her partner…it is a 3-minute love affair and energy exchange. I love Bachata because I can get out of my head and just feel, express my sensuality, be playful and connect… it balances out my left brained day job.”

More than 20 years ago, scientists found a connection between music and enhancement of performance or changing of neuropsychological activity involving Mozart’s music from which the theory of “The Mozart Effect” was derived. The basis of The Mozart Effect lies at the super-organization of the cerebral cortex that might resonate with the superior architecture of Mozart’s music. Basically listening to Mozart K.448 enhances performance on spatial tasks for a period of approximately 20 min.

So dear reader, please stop complaining and making excuses and just dance! Or at least listen to music, as the outstanding jazz singer Tamar Korn once told me when I was in distress “music heals”.

 

This post was originally published on Dec 30, 2015 and was updated with new research on Dec 12, 2016 and on Dec 19, 2017.

Is Your Deodorant Bad For Your Health?

 

By Jesica Levingston Mac Leod, PhD

Body odors (BO) are part of our evolution, and the ability to smell has evolved with us, making people fall in love or run away from a smelly person. Sweat has an initial effect to cool our body down and avoid overheating. Sweat can also be trigger by stress, anxiety or other hormonal changes. Sweat by itself doesn’t smell, but the bacteria located near the glands, for example, the armpits, breakdown the sweat generating the “BO”. How do we deal with the stinky fact? We apply deodorants and/or antiperspirants. Deodorants have ingredients like triclosan, which make the skin more salty or acidic for the bacteria to grow in those areas. Therefore deodorants don’t stop you from sweating, but antiperspirants will do the trick, as they contain ingredients like aluminum and zirconium, which are taken up through the pores and they react with water and swell, forming a gel that blocks the sweat.

Last year, Mandriota and collaborators demonstrated that in a cancer mouse model, concentrations of aluminum in the amount of those measured in the human breast are able to transform cultured mammary epithelial cells, allowing them to form tumors and to metastasize. Moreover, aluminum salts have been linked with DNA damage, oxidative stress, and estrogen action. In 2004, a woman reported aluminum poisoning after using antiperspirants for four years, and after stopping the use of these products the aluminum levels dropped and she recovered.

Breast cancer develops after cells with mutations in their DNA start growing uncontrolled, generating a tumor. Most breast cancers develop in the upper outer quadrant of the breast, near to the lymph nodes that are exposed to antiperspirants. This fact was the starting point for the theories that the underarm cosmetic products could be carcinogenic. One of the first publications on this subject dates from 2002; it was population-based (ages 20-74, 1606 patients) and found no correlation between breast cancer and antiperspirant use. A second article found a relationship between an earlier age of breast cancer diagnosis to more frequent regular use of antiperspirants/deodorants and underarm shaving.

Aluminum salts have been linked to increased risk of developing breast cancer, but so far the research on this has been quite inconsistent. Last month, a new research study of 418 women (ages 20 to 85) examined their self-reported history of use of underarm cosmetic products and health status, in order to unveil a bit more about the link between antiperspirants and breast cancer. Linhart and col. from Austria, studied the relationship of the use of underarm cosmetic products and the risk of breast cancer. They divided the group in two: half of the women were breast cancer patients and the other half healthy controls. Then, they measured the concentration of aluminum in the breast tissue of some of the women. The results showed that the risk of breast cancer increased by an odd ratio of 3.88 in females who described using the underarm products multiple times per day starting before their 30th birthday. Importantly: “aluminum traces were found in the breast tissue in both cancer patients and healthy controls and it was significantly associated to self-reported underarm cosmetic products use”. In fact, the median concentrations of aluminum were 5.8 (2.3-12.9) nmol/g in the tissues from breast cancer patients versus 3.8 (2.5-5.8) nmol/g in controls. The conclusion is that more than daily use of these cosmetic products at younger ages may lead to the accumulation of aluminum in breast tissue and increase the risk of breast cancer.

Although the American Cancer Society claims that “there are no strong epidemiologic studies in the medical literature that link breast cancer risk and antiperspirant use”, after the Linhart investigation, and knowing that 1 in 8 women will be diagnosed with breast cancer in her lifetime, I will avoid antiperspirants with aluminum. Nobody wants to be called “stinky”, so some actions to take are to wash your clothes after working out, take showers regularly and/or clean your armpits with water and soap as soon as you “smell something”, apply deodorant, and consult with your doctor about the best way to keep your body odors under control. The last resource: perfume. If you can’t win the fight… hide.

HeLa, the VIP of cell lines

By  Gesa Junge, PhD

A month ago, The Immortal Life of Henrietta Lacks was released on HBO, an adaptation of Rebecca Skloot’s 2010 book of the same title. The book, and the movie, tell the story of Henrietta Lacks, the woman behind the first cell line ever generated, the famous HeLa cell line. From a biologist’s standpoint, this is a really unique thing, as we don’t usually know who is behind the cell lines we grow in the lab. Which, incidentally, is at the centre of the controversy around HeLa cells. HeLa was the first cell line ever made over 60 years ago and today a PubMed search for “HeLa” return 93274 search results.

Cell lines are an integral part to research in many fields, and these days there are probably thousands of cell lines. Usually, they are generated from patient samples which are immortalised and then can be grown in dishes, put under the microscope, frozen down, thawed and revived, have their DNA sequenced, their protein levels measured, be genetically modified, treated with drugs, and generally make biomedical research possible. As a general rule, work with cancer cell lines is an easy and cheap way to investigate biological concepts, test drugs and validate methods, mainly because cell lines are cheap compared to animal research, readily available, easy to grow, and there are few concerns around ethics and informed consent. This is because although they originate from patients, the cell lines are not considered living beings in the sense that they have feelings and lives and rights; they are for the most part considered research tools. This is an easy argument to make, as almost all cell lines are immortalised and therefore different from the original tissues patients donated, and most importantly they are anonymous, so that any data generated cannot be related back to the person.

But this is exactly what did not happen with HeLa cells. Henrietta Lack’s cells were taken without her knowledge nor consent after she was treated for cervical cancer at Johns Hopkins in 1951. At this point, nobody had managed to grow cells outside the human body, so when Henrietta Lack’s cells started to divide and grow, the researchers were excited, and yet nobody ever told her, or her family. Henrietta Lacks died of her cancer later that year, but her cells survived. For more on this, there is a great Radiolab episode that features interviews with the scientists, as well as Rebecca Skloot and Henrietta Lack’s youngest daughter Deborah Lacks Pullum.

In the 1970s, some researchers did reach out to the Lacks family, not because of ethical concerns or gratitude, but to request blood samples. This naturally led to confusion amongst family members around how Henrietta Lack’s cells could be alive, and be used in labs everywhere, even go to space, while Henrietta herself had been dead for twenty years. Nobody had told them, let alone explained the concept of cell lines to them.

The lack of consent and information are one side, but in addition to being an invaluable research tool, cell lines are also big business: The global market for cell lines development (which includes cell lines and the media they grow in, and other reagents) is worth around 3 billion dollars, and it’s growing fast. There are companies that specialise in making cell lines of certain genotypes that are sold for hundreds of dollars, and different cell types need different growth media and additives in order to grow. This adds a dimension of financial interest, and whether the family should share in the profit derived from research involving HeLa cells.

We have a lot to be grateful for to HeLa cells, and not just biomedical advances. The history of HeLa brought up a plethora of ethical issues around privacy, information, communication and consent that arguably were overdue for discussion. Innovation usually outruns ethics, but while nowadays informed consent is standard for all research involving humans, and patient data is anonymised (or at least pseudonomised and kept confidential), there were no such rules in 1951. There was also apparently no attempt to explain scientific concept and research to non-scientists.

And clearly we still have not fully grasped the issues at hand, as in 2013 researchers sequenced the HeLa cell genome – and published it. Again, without the family’s consent. The main argument in defence of publishing the HeLa genome was that the cell line was too different from the original cells to provide any information on Henrietta Lack’s living relatives. There may some truth in that; cell lines change a lot over time, but even after all these years there will still be information about Henrietta Lack’s and her family in there, and genetic information is still personal and should be kept private.

HeLa cells have gotten around to research labs around the world and even gone to space and on deep sea dives. And they are now even contaminating other cell lines (which could perhaps be interpreted as just karma). Sadly, the spotlight on Henrietta Lack’s life has sparked arguments amongst the family members around the use and distribution of profits and benefits from the book and movie, and the portrayal of Henrietta Lack’s in the story. Johns Hopkins say they have no rights to the cell line, and have not profited from them, and they have established symposiums, scholarships and awards in Henrietta Lack’s honour.

The NIH has established the HeLa Genome Data Access Working Group, which includes members of Henrietta Lack’s family. Any researcher wanting to use the HeLa cell genome in their research has to request the data from this committee, and explain their research plans, and any potential commercialisation. The data may only be used in biomedical research, not ancestry research, and no researcher is allowed to contact the Lacks family directly.

End Crisis, Bridges and Scattered Genes: Chromatin Bridges and their Role in Genomic Stability

By Gesa Junge, PhD

Each of our cells contains about two meters of DNA which needs to be stored in cells that are often less than 100uM in diameter, and to make this possible, the DNA is tightly packed into chromosomes. As the human cell prepares to divide, the 23 pairs of chromosomes neatly line up and attach to the spindle apparatus via their middle point, the centrosome. The spindle apparatus is part of the cell’s scaffolding and it pulls the chromosomes to opposite ends of the cell as the cell divides, so that every new daughter cell ends up with exactly one copy of each chromosome. This is important; cells with more or less than one copy of a chromosome are called aneuploid cells, and aneuploidy can lead to genetic disorders such as Down Syndrome (three copies of chromosome 21).

In some cancer cells, chromosomes with two centromeres (dicentric chromosomes) can be detected, which can happen when the ends of two chromosomes fuse in a process called telomere crisis. Telomeres are a sort of buffer zone at the ends of the chromosome which consist of repeats of non-coding DNA sequences, meaning there are no genes located here. As one of the DNA strands is not replicated continuously but in fragments, the telomeres get shorter over the lifespan of a cell, and short telomeres can trigger cell cycle arrest before the chromosomes get so short that genetic information is lost. But occasionally, and especially in cancer cells, chromosome ends fuse and a chromosome becomes dicentric. Then it can attach to the spindle apparatus in two points and may end up being pulled apart as the two daughter cells separate, sort of like a rope tied to two cars that drive in opposite directions. This string of chromosome is referred to as a chromatin bridge.

Researchers at Rockefeller University are studying these chromatin bridges and what their relevance is for the health of the cell. A paper by John Maciejowski and colleagues found that the chromatin bridges actually stay intact for quite a long time. Chromosomes are pretty stable, and so the chromatin bridges lasted for an average of about 9 hours (3-20h) before snapping and quickly being pulled back into the original cell (see video). Also, the nucleus of the cell was often heart-shaped as opposed to the usual round shape, which suggests that the chromatin bridge physically pulls on the membrane surrounding the nucleus, the nuclear envelope. Indeed, proteins that make up the nuclear envelope (e.g. LAP2) were seen on the chromatin bridge, suggesting that they take part of the nuclear envelope with them as they divide.  Also, cells with chromatin bridges had temporary disruptions to their nuclear envelope at some point after the bridge was resolved, more so than cells without chromatin bridges.

The chromatin bridges also stained positive for replication protein A (RPA), which binds single stranded DNA. DNA usually exists as two complementary strands bound together, and the two strands really only separate to allow for DNA to be copied or transcribed to make protein. Single-stranded DNA is very quickly bound by RPA, which stabilises it so it does not loop back on itself and get tangled up in secondary structures. The Rockefeller study showed that a nuclease, a DNA-eating enzyme, called TREX1 is responsible for generating the single-stranded DNA on chromatin bridges. And this TREX1 enzyme seems to be really important in resolving the chromatin bridges: cells that do not have TREX1 resolve their chromatin bridges later than cells that do have TREX1.

So how are chromatin bridges important for cells, the tissue and the organism (i.e. us)? The authors of this study suggest that chromatin bridges can lead to a phenomenon called chromothripsis. In chromothripsis, a region of a chromosome is shattered and then put back together in a fairly random order and with some genes facing the wrong direction. Think of a new, neatly color-sorted box of crayons that falls on the floor, and then someone hastily shoves all the crayons back in the box with no consideration for color coordination or orientation. Chromothripsis occurs in several types of cancers, but it is still not really clear how often, in what context and exactly how the genes on a chromosome end up in such a mess.

According to this study, chromothripsis may be a consequence of telomere crisis, and chromatin bridges could be part of the mechanism: A chromosome fuses ends with another chromosome and develops two centromeres. The dicentric chromosome attaches to two opposite spindles and is pulled apart during cell division, generating a chromatin bridge which is attacked by TREX that turns it into single-stranded DNA, the bridge snaps and in the process the DNA scatters, and returns to the parent cell where it is haphazardly reassembled, leaving a chromothripsis region.

The exact mechanisms of this still need to be studied and the paper mentions a few important discussion points. For example, all the experiments were performed in cell culture, and the picture may look very different in a tumor in a human being. And what exactly causes the bridge to break? Also, there are probably more than one potentially mechanism linking telomere crisis to chromothripsis. But it is a very interesting study that shines some light on the somewhat bizarre phenomenon of chromothripsis, and the importance of telomere crisis.

Reference: Maciejowski et al, Cell. 2015 Dec 17; 163(7): 1641–1654.

 

 

Immunotherapy: Using Your Own Cells to Fight Cancer – Part 2

 

By Gesa Junge, PhD

 

Part 1 of this post described passive immunotherapies like antibodies and cytokines, but there are also active immunotherapies, which re-target our immune system towards cancer cells, for example cancer vaccines. These can be preventative vaccines, offering protection against cancer-associated viruses such as Hepatitis B (liver cancer) or Human Papilloma Virus (HPV, cervical cancer). The link between HPV and cervical cancer was first described in 1983, and a vaccine was approved in 2006. By 2015, the incidence of HPV infections in women under 20 had decreased as much as 60% in countries that had 50% vaccination coverage, although it may still be too early to tell what the impact on HPV-associated cancer incidence is. There are also other factors to consider, for example screening programmes are also likely to have a positive impact on HPV-associated cancers.

Vaccines can also be therapeutic vaccines, which stimulate the immune system to attack cancer cells. To date, the only cancer vaccine approved in the US is Provenge, used for the treatment of metastatic prostate cancer. For this therapy, a patient’s white blood cells are extracted from the blood, incubated with prostatic acid phosphatase (PAP, a prostate-specific enzyme) and granulocyte macrophage colony stimulating factor (GM-CSF) in order to produce mature antigen presenting cells which are then returned to the patient and search and destroy tumour cells.

Many other therapeutic cancer vaccines are in development, for example OncoVax, which is an autologous vaccine made from a patient’s resected tumour cells. OncoVax has been in development since the 1990s and is currently in phase III trials. Another example is GVAX, an allogenic whole-cell tumour vaccine currently being studied in phase I and II trials or pancreatic and colorectal cancer. As an allogenic vaccine, it is not made from the patient’s own blood cells (like an autologous vaccine), and it does not target specific antigens but rather increases the production of cytokines and GM-CSF.

Another therapy which is based on re-programming the patient’s immune system is adoptive T-cell transfer. As with some cancer vaccines, a patient’s T-cells are isolated from the blood, and the cells with the greatest affinity for tumour cells are expanded in the lab and the re-infused in the patient. A recent modification of this technique is the use of chimeric antigen receptor (CAR) T-cells, where the T-cell receptors are genetically engineered to be more tumour-specific before re-infusion. This approached was especially promising in chronic lymphocytic leukaemia, where some patients experienced remissions of a year and longer. Later, CAR T-cells were also tested in acute lymphocytic leukaemia, where response rates were as high as 89%.

Finally, a new class of cancer drugs called immune checkpoint inhibitors has been making headlines recently, some of which are now approved for the treatment of cancer. Immune checkpoints are part of the mechanism by which human cells, including cancer cells, can evade the immune system. For example, the programmed cell death (PD) 1 receptor on immune cells interacts with PD1 ligand (PDL1) on cancer cells, which inhibits the killing of the cancer cell by the immune cell. Similarly, CTLA-4 is a receptor on activated T-cells which downregulates the immune response.

The first checkpoint inhibitor was an antibody to CTLA-4, ipilimumab, which was approved for the treatment of melanoma in 2011. PD1 antibodies such as pembrolizumab and nivolumab were only approved in 2014, and the only PDL1 antibody (atezolizumab) in 2016, so it is difficult to tell what the long-term effects of checkpoint inhibitor treatment will be. Numerous checkpoint inhibitors are still undergoing trials, most of the advanced (phase III) ones being targeted to PD1 or PDL1. However, there are other compounds in early trials (phase I or II) that target KIR (killer-cell immunoglobulin-like receptor) which are primarily being studied in myeloma, or LAG3 (lymphocyte activation gene 3), in trials for various solid tumours and leukaemias.

Immunotherapies all come under the umbrella of biological therapies. Biologics are produced by organisms, usually cells in a dish, unlike synthetic drugs, which are manufactured using a chemical process in the lab. This makes biologicals more expensive to manufacture. Ipilimumab therapy, for example, can cost about $100 000 per patient, with pembrolizumab and nivolumab being only slightly less expensive at $48 000 – $67 000. This puts considerable financial strain on patients and insurance companies. From a safety perspective, biologicals can cause the immune system to overreact. This sounds odd, as the whole point of immunotherapy is to activate the immune system in order to fight tumour cells, but if this response gets out of control, it can lead to potentially serious side effects as the immune system attacks the body’s organs and tissues.

All of these therapeutic approaches (antibodies, interleukins, vaccines, and checkpoint inhibitors) are usually not used alone but in combination with each other or other chemotherapy, which makes it difficult to definitively say which drug works best. But it is safe to say that collectively they have improved the lives of a lot of cancer patients. If you are interested in finding out more about the fascinating history of immunotherapy, from the discovery of the immune system to checkpoint inhibitors, check out the CRI’s timeline of progress on immunology and immunotherapy here.

 

Immunotherapy: Using Your Own Cells to Fight Cancer – Part 1

 

By Gesa Junge, PhD

 

Our immune system’s job is to recognize foreign, unfamiliar and potentially dangerous cells and molecules. On the one hand, it helps us fight infections by bacteria and viruses, while on the other hand it can leave us with annoying and potentially dangerous allergic reactions to harmless things like peanuts, pollen or pets. Tumor cells are arguably very harmful to our health, and yet the immune system does not always eliminate them. This is partially because cancer cells are our own cells, and not a foreign, unfamiliar intruder.

The immune system can recognize cancer cells; this was first postulated in 1909 by Paul Ehrlich and subsequently found by several others. However, detecting cancer cells may not be enough to prevent tumor growth. Recent research has shown that while detection can lead to elimination of cancer cells, some cells are not killed but enter an equilibrium stage, where they can exist undisturbed and undergo changes, and finally the cells can escape, if they have changed in a way that allows them to grow undetected by the immune system. This process of elimination, equilibrium and escape is referred to as “cancer immunoediting” and is one of the most active research areas in cancer, particularly in regard to cancer therapy.

Immunotherapy is a form of cancer therapy that harnesses our immune system to kill cancer cells, and there are various approaches to this. Probably the most established forms of immunotherapy are antibodies, which have been used for almost two decades. They generally target surface markers of cancer cells; for example, rituximab is an antibody to CD20, or trastuzumab, which targets HER2. CD20 and HER2 are cell surface proteins highly expressed by leukaemia and breast cancer cells, respectively, while normal, healthy cells have lower expression, making the cancer cells more susceptible. Rituximab was approved for Non-Hodgkins Lymphoma in 1997, the first of now nearly 20 antibodies to be routinely used in cancer therapy. In addition to this, there are several new antibodies undergoing clinical trials for most cancers. These are mainly antibodies to tumour-specific antigens (proteins that may only be expressed by e.g. prostate or lung cancer), and checkpoint inhibitors such as PD1 (more on that in part 2).

Initially, antibodies were usually generated in mice; however, giving murine antibodies to humans can lead to an immune response and resistance to the mouse antibodies when they are administered again later. Therefore, antibodies had to be “humanised”, i.e. made more like human antibodies, without losing the target affinity, and this was only made possible by advances in biotechnology. The first clinically used antibodies, such as rituximab, were chimeric antibodies, in which the variable region (which binds the target) is murine and the constant region is human, making them much better tolerated. Trastuzumab is an example of a humanised antibody, where only the very end of the variable region (the complementarity-determining region, CDR) is murine, and the rest of the molecule is human). And then there are fully human antibodies, such as panitumumab, an anti-EGFR antibody used to treat colorectal cancer. There is actually a system to labeling therapeutic antibodies: -ximab is chimeric, -zumab is humanised and –umab is human.

Antibodies can also be conjugated to drugs, which should make the drug more selective to its target and the antibody more effective in cell-killing. So far there are only very few antibody-drug conjugates in clinical use, but one example is Kadcyla, which consists of trastuzumab conjugated to emtansine, a cytotoxic agent.

Other examples of immunotherapy are cytokines such as interferons and interleukins. These are mediators of the immune response secreted by immune cells which can be given intravenously to help attack cancer cells, and they are used for example in the treatment of skin cancer. Interleukin 2 (IL-2) was the first interleukin to be approved, for the treatment of advanced melanoma and renal cancer, and research into new interleukins and their therapeutic potential is still going strong. Especially IL-2 and IL-12, but also several others are currently in clinical studies for both and various other indications, such as viral infections and autoimmune diseases.

In addition to passive immunotherapies like antibodies and cytokines, there are also active immunotherapies which re-target our immune system towards cancer cells, for example cancer vaccines. More on this, and on new drugs and their issues in part 2.

 

 

 

How a Cancer’s Genome Can Tell Us How to Treat it

By Gesa Junge, PhD

 

Any drug that is approved by the FDA has to have completed a series of clinical trials showing that the drug is safe to use and brings a therapeutic benefit, usually longer responses, better disease control, or fewer toxicities.

Generally, a phase I study of a potential cancer drug will include less than a hundred patients with advanced disease that have no more treatment options, and often includes many (or all) types of cancer. The focus in Phase I studies is on safety, and on finding the best dose of the drug to use in subsequent trials. Phase II studies involve larger patient groups (around 100 to 300) and the aim is to show that the treatment works and is safe in the target patient population, while Phase III trials can involve thousands of patients across several hospitals (or even countries) and aims to show a clinical benefit compared to existing therapies. Choosing the right patient population to test a drug in can make the difference between a successful and a failed drug. Traditionally, phase II and III trial populations are based on tumour site (e.g. lung or skin) and/or histology, i.e. the tissue where the cancer originates (e.g. carcinomas are cancer arising from epithelial tissues, while sarcomas develop in connective tissue).

However, as our understanding of cancer biology improves, it is becoming increasingly clear that the molecular basis of a tumour may be more relevant to therapy choice than where in the body it develops. For example, about half of all cutaneous melanoma cases (the most aggressive form of skin cancer) have a mutation in a signalling protein called B-Raf (BRAF V600). B-Raf is usually responsible for transmitting growth signals to cells, but while the normal, unmutated protein does this in a very controlled manner, the mutated version provides a constant growth signal, causing the cell to grow even when it shouldn’t, which leads to the formation of a tumour. A drug that specifically targets and inhibits the mutated version of B-Raf, Vemurafenib, was approved for the treatment of skin cancer in 2011, after trials showed it lead to longer survival and better response rates compared to the standard therapy at the time. It worked so well that patients in the comparator group were switched to the vemurafenib group halfway through the trial.

While B-Raf V600 mutations are especially common in skin cancer, they also occur in various other cancers, although at much lower percentages (often less than 5%), for example in lung and colorectal cancer. And since inhibition of B-Raf V600 works so well in B-Raf mutant skin cancer, should it not work just as well in lung or colon cancer with the same mutation? As the incidence of B-Raf V600 mutations is so low in most cancers, it would be difficult to find enough people to conduct a traditional trial and answer this question. However, a recently published study at Sloan Kettering Cancer Centre took a different approach: This study included 122 patients with non-melanoma cancers positive for B-Raf V600 and showed that lung cancer patients positive for B-Raf V600 mutations responded well to Vemurafenib, but colorectal cancer patients did not. This suggests that the importance of the mutated B-Raf protein for the survival of the tumour cells is not the same across cancer types, although at this point there is no explanation as to why.

Trials in which the patient population is chosen based on tumour genetics are called basket trials, and they are a great way to study the effect of a certain mutation on various different cancer types, even if only very few cases show this mutation. A major factor here is that DNA sequencing has come a long way and is now relatively cheap and quick to do. While the first genome that was sequenced as part of the Human Genome Project cost about $2.7bn and took over a decade to complete, a tumour genome can now be sequenced for around $1000 in a matter of days. This technological advance may make it possible to routinely determine a patient’s tumour’s DNA code and assign them to a therapy (or a study) based on this information.

The National Cancer Institute is currently running a trial which aims to evaluate this model of therapy. In the Molecular Analysis for Therapy Choice (MATCH) Trial, patients are assigned to a therapy based on their tumour genome. Initially, only ten treatments were included and the study is still ongoing, but an interim analysis after the 500th patient had been recruited in October 2015 showed that 9% of patients could be assigned to therapy based on mutations in their tumour, which is expected to increase as the trial is expanded to include more treatments.

This approach may be especially important for newer types of chemotherapy, which are targeted to a tumour-specific mutation that usually causes a healthy cell to become a cancer cell in the first place, as opposed to older generation chemotherapeutic drugs which target rapidly dividing cells and are a lot less selective. Targeted therapies may only work in a smaller number of patients, but are usually much better tolerated and often more effective, and molecular-based treatment decisions could be a way to allow more patients access to effective therapies faster.

Repair Gone Wrong: Targeting The DNA Damage Response To Treat Cancer

By Gesa Junge, PhD

 

Our cells are subject to damage every minute of every day, be it from endogenous factors such as reactive oxygen species generated as part of normal cell respiration, or exogenous factors such as UV radiation from the sun. Together, these factors can lead to as many as 60 000 damaged DNA bases per cell per day. Most of these are changes to the DNA bases or single strand breaks (SSBs), which only affect one strand of the double helix, and can usually be repaired before the DNA is replicated and the cell divides. However, about 1% of SSBs escape and become double stand breaks (DSBs) upon DNA replication. DSBs are highly toxic, and a single DSB can be lethal to a cell if not repaired.

Usually, cells are well-equipped to deal with DNA damage and have several pathways that can remove damaged DNA bases and restore the DNA sequence. Nucleotide excision repair (NER, e.g. for UV damage) and base excision repair (BER, for oxidative damage) are the main SSB repair pathways, and homologous recombination (HR) and non-homologous enjoining (NHEJ) repair most DSBs. HR is the more accurate pathways for DSB repair, as it relies on a homologous DNA sequence on the sister chromosome to restore the damaged bases, whereas NHEJ simply relegates the ends of the break, potentially losing genetic information. However, NHEJ can function at any time in the cell cycle whereas HR requires a template and is only active once the DNA is replicated (i.e. in G2 and S-phase).

Depending on the severity of the damage, cells can either stop the cell cycle to allow for repair to take place or, if the damage is too severe, undergo apoptosis and die, which in a multicellular organism is generally favourable to surviving with damaged DNA. If cells are allowed to replicate with unrepaired DNA damage, they pass this damage on to their daughter cells in mitosis, and mutations in the DNA accumulate. While mutations are essential to evolution, they can also be problematic. Genomic instability, and mutations in genes such as those that control the cell cycle and the DNA damage response can increase the risk of developing cancer. For example, germline mutations in ATM, a key protein in HR pathway of DSB repair, leads to Ataxia Telangiectasia (AT), a neurodegenerative disorder. AT sufferers are hypersensitive to DSB-inducing agents such as x-rays, and have a high risk of developing cancer. Deficiencies in NER proteins lead to conditions such as Xeroderma Pigmentosa or Cockayne Syndrome which are characterised by hypersensitivity to UV radiation and an increased risk of skin cancer, and mutations BRCA2, another key HR protein, increase a woman’s risk of developing breast cancer to 60-80% (compared to 13% on average).

Even though deficiencies in DNA repair can predispose to cancer, DNA repair is also emerging as a viable target for cancer therapy. For example, DNA repair inhibitors can be used to sensitise cancer cells to chemotherapy- or radiation-induced damage, making it possible to achieve more tumour cell kill with the same dose of radiation or chemotherapy. However, this approach is not yet used clinically and a major complication is that it often increases both the efficacy as well as the toxicity of treatment.

Another approach is the idea of “synthetic lethality”, which relies on a cancer cell being dependent on a specific DNA repair pathway because it is defective in another, such that deficiency of either one of two pathways is sustainable, but loss of both leads to cell death. This concept was first described by Calvin Bridges in 1922 in a study of fruit flies and is now used in the treatment of breast cancer in the form of an inhibitor of Poly-ADP ribose polymerase (PARP), a key enzyme in the repair of SSBs. Loss of PARP function leads to increased DSBs after cell division due to unrepaired SSBs, which in normal tissue are removed by the DSB repair system. However, BRCA2-deficient tumours are defective in HR and cannot repair the very toxic DSBs, leading to cell death. Therefore, BRCA2-deficient tumours are hypersensitive to PARP inhibitors, which are now an approved therapy for advanced BRCA2-deficient breast and ovarian cancer.

PARP inhibitors are a good example of a so-called “target therapy” for cancer, which is the concept of targeting the molecular characteristics that distinguish the tumour cell from healthy cells (in this case, BRCA2 deficiency), as opposed to most older, cytotoxic chemotherapies, which generally target rapidly dividing cells by inducing DNA damage, and can actually lead to second cancers. With an improved understanding of the molecular differences between normal and tumour cells, cancer therapy is slowly moving away from non-specific cytotoxic drugs towards more tolerable and effective treatments.

From String to Strand

 

By Jordana Lovett

 

Ask a molecular biologist what image DNA conjures up in the mind. A convoluted ladder of nitrogenous bases, twisting and coiling dynamically. Pose the very same question to a theoretical physicist- chances are that DNA takes on a completely different meaning. As it turns out, DNA is in the eye of the beholder. Science is about perspective. Moreover, it relies on the convergence of distinct, yet interrelated angles to tackle scientific questions wholly.

 

When I met Dr. Vijay Kumar at a Cancer Immunotherapy meeting, I was immediately intrigued by his unique background and path to biology.  Vijay largely credits his family for strongly instilling in him core values of education and assiduousness. He was raised to strive for the best, and was driven to satisfy the goals of his parents, who encouraged him to pursue a degree in electrical engineering. While slightly resentful at the time, he now realizes that this broad degree would afford him multiple career options as well as the opportunity to branch into other fields of physics in the future. As early as his teenage years, Vijay had already begun thinking about the interesting unknowns of the natural universe. With his blinders on, he sought to explore them using physics and math, both theoretically and practically. As he advanced to university in pursuance of a degree in electrical engineering, he strategized and planned what would be his future transition into theoretical physics. He dabbled in various summer research projects and sought mentorship to help guide his career. Vijay ultimately applied and was accepted to a PhD program at MIT, where he studied string theory in a 6-dimensional model universe. He describes string theory as a broad framework rather than a theory that can be related to the world through ‘thought experiments’ and mathematical consistency.  Kumar continued his work in string theory during a post-doc in Santa Barbara, California, where he found himself surrounded by a more diverse group of physicists. Theoretical physicists, astrophysicists, and biophysicists were able to intermingle and share their science.

 

This diversity spurred new perspectives and reconsideration of what he had originally thought would be a clear road to professorship and a career in academia. As one would imagine, the broader impacts of string theory are limited; the ideas are part of a specialized pool of knowledge available to an elite handful. Even among the few, competition was fierce- at the time, there were only two available openings for professors in string theory in the United States. Additionally, seeing the need and presence of ‘quantitative people’ in other fields, such as biology made him increasingly curious about alternatives to the automated choices he had been making until this point. With the support of his (now) wife, and inspiration from his brother (who had just completed a degree in statistics/informatics and started a PhD in biology), he networked with other post-docs and set up meetings with principle investigators (PI’s) to discuss how he, as a theoretical physicist, could play a role in a biological setting. He spent time during his post-doc in Santa Barbara, and throughout his second post-doc at Stony Brook reflecting, taking courses and shifting into a different mindset. Vijay interviewed and gave talks at a number of institutions, and eventually landed in lab at Cold Spring Harbor, where he now is involved in addressing some of the shortcomings in DNA sequencing technology.

 

Starting in a different lab within the confines of a field means readjusting to brand new settings, acquainting with new lab mates and shifting from one narrowly focused project to another. Launching not only into a new lab, but into a foreign field adds an extra unsettling and daunting layer to the scenario.  Vijay, however, viewed this as yet another opportunity to uncover mysteries in nature- through a new perspective.  He recognized an interplay between string theory, wherein the vibration of strings allows you to make predictions about the universe, and biology, where the raw sequence of DNA can inform the makeup of an organism, and its interactions with the world.  It is with this viewpoint that Vijay understands DNA. He sees it as an abstraction, as a sequence of letters that allows you to draw inferences and predict biological outcomes. A change or deletion in just one letter can have enormous, tangible effects. It is this tangibility that speaks to Vijay. He is drawn to the application and broader consequences of the work he is doing, and excited that he can use his expertise to contribute to this knowledge.

 

While approaching a radically different field can impose obstacles, Kumar sees common challenges in both physics and biology and simply avoids getting lost in scientific translation. Just as theory has a language, so too biology has its own jargon. Once past this barrier, addressing gaps in knowledge becomes part of the common scientific core. Biology enables a question to be answered through various assays and allows observable results to guide future experiments- expertise in various subjects is therefore not only encouraged, but necessary. Collaborations between different labs across various disciplines enable painting a complete picture. “I’m a small piece of a larger puzzle, and that’s ok”, says Vijay. His insight into how scientists ought to work is admirable. Sharing and communicating data in a way that is comprehendible across the scientific playing field will more quickly and efficiently allow for scientific progress.

 

If I’ve learned one thing from Vijay’s story, it is to understand that science has room for multiple perspectives. In fact, it demands questions to be addressed in an interdisciplinary fashion. You might question yourself along the way. You might shift gears, change directions. But these unique paths mold the mind to perceive, ask, challenge, and contribute in a manner that no one else can.

RESIDENT LYMPHOCYTES KEEP A LOOKOUT FOR NASCENT CANCER CELLS

 

By Sophie Balmer, PhD

One of the first questions that comes to my mind when discussing the emergence of cancer cells is how my immune system recognizes that my own cells have been transformed? This process is commonly termed cancer immunosurveillance. In the prevalent model, the adaptive immune system composed of lymphocytes circulating in the blood stream plays the main function. However, recent findings describe specific immune cells already present within the tissue, a.k.a. tissue-resident lymphocytes, and how they trigger the first immune response against cancer cells, allowing a much faster reaction in an attempt to eradicate transformed cells.

 

The cancer immunosurveillance concept hypothesizes that sentinel thymus-derived immune cells constantly survey tissues for the presence of nascent transformed cells. Cancer immunosurveillance was first suggested in the early 1900’s by Dr. Erlich but it took another fifty years for Dr. Thomas and Dr. Burnet to revisit this model and speculate about the presence of transformed cells induced inflammation and antigen-specific lymphocyte responses. Additionally, Dr. Prehn and Dr. Main estimated that chemically-induced tumor triggered the synthesis of antigen at the surface of cancerous cells that could be recognized by the immune system. Countless studies arose from these hypotheses and either validated or disproved these models. The latest attempt was published a little over a month ago, in a paper by Dr. Dadi and colleagues, describing a new mechanism for the immune system to respond to nascent cancer lesions by activating specific resident lymphocytes.

 

In this study, the authors used a genetically-induced tumor model (the MMTV-PyMT spontaneous mammary cancer mouse model) to analyze the in vivo response of the immune system to nascent transformed cells. Most studies have been performed using chemically-induced tumors or tumor transplantation into a healthy host but these do not account for the initial environment of the nascent tumor. The spontaneous model the authors use rapidly exhibits developing cancer lesion (in 8-week old mice), allowing the analysis of cellular populations present near transformed cells.

 

To analyze which immune cell types are present near cancer lesions, the authors performed several analyses. First, they measure the levels of granzyme B, a serine protease found in granules synthesized by cytotoxic lymphocytes to generate apoptosis of targeted cells, and show that PyMT mice have elevated levels of granzyme B when compared to wild-type mouse. Moreover, similar analysis of PyMT secondary lymphoid organs show that this response was restricted to the transformed tissue.

During the first steps of immune responses, conventional natural killer (cNK) cells as well as innate lymphoid cells (ILC) are found in tumor microenvironments. In this model however, sorting of cells located in the vicinity of the lesion identified unconventional populations of immune cells, derived from innate, TCRab and TCRgd lineages. Indeed, their RNA-seq profiling reveal a specific gene signature characterized by high expression of the NK receptor NK1.1 but also the integrins CD49a and CD103. As these newly identified cells share part of their transcriptome with type 1 ILCs, the authors named them type 1-like ILCs (ILC1ls) and type 1 innate-like T cells (ILTC1s). In addition, transcripts encoding several immune effectors as well as apoptosis-inducing factors are upregulated in these cells, likely indicating that they trigger several pathways to eliminate transformed cells.

The authors also suggest that cNK cells are not required for immunosurveillance in this model and the unconventional lymphocytes described in this paper are regulated by the interleukine-15 (IL-15) in a dose-dependent way. Mice overexpressing IL-15 exhibit higher proliferation of these resident lymphocytes and tumor regression. Secretion of IL-15 in the tumor microenvironment might therefore promote cancer immunosurveillance.

 

In contradiction with the conventional view that recirculating populations of immune cells survey tissues for cellular transformation, ILC1ls and ILTC1s are tissue-resident lymphocytes. Their gene signature indicates that transcripts encoding motility-related genes are downregulated in these cells. Moreover, parabiosis experiments, during which two congenically marked mice are surgically united and share their blood stream, are performed to determine whether they are resident or circulating cells. The amounts of non-host ILC1s and ILTC1s are much reduced when compared to other recirculating immune cell type demonstrating that these cells are tissue-resident lymphocytes. Single-cell killing assays also determine that ILC1ls and ILTC1s are highly efficient at inducing apoptosis of tumor cells, which is more likely dependent on the lytic granules pathway.

 

Although the cancer immunosurveillance concept has been around for decades, it is still highly debated. Overall, these results shed light on this confusing field and bring up several questions. The signals recognized by this immune response are still unknown. Although the authors suggest that IL-15 might regulate the proliferation and/or activation of these cells, the source of IL-15 remains to be found. In addition, these cells might promote cancer immunosurveillance but are not sufficient to eradicate tumor cells and determining the cascade of signals induced by these resident lymphocytes will be required to ascertain their role. Establishing the limit of their efficiency as well as the mechanisms activated by transformed cell to escape their surveillance will also be crucial. Finally, one of the most important question to consider is how one could manipulate the activity of tissue-resident lymphocytes in cancer immunotherapy.