Behrens lab retreat 2016

Imagine spending a weekend in these idyllic surroundings in the Peak District with nothing to do but talk about and discuss science.

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The Peak Mermaid Inn – taken at sunrise on November 13th 2016

Well, that’s exactly what we, the Behrens lab, did last weekend. We invited a keynote speaker, Roland Rad, and Dieter Saur’s group from the Technical University of Munich to join us. Each of us gave a talk about the most interesting or exciting aspects of our projects and in between we drank copious amounts of coffee. In the evenings we cooked enough food to feed a small regiment, drank beer, played pool, darts or table football, all punctuated by heated debates about science. Although this wasn’t a relaxing weekend by normal standards, it was motivating and inspiring and a good reminder of why I enjoy being a scientist: a combination of rational and logical thinking, curiosity and the drive to learn new things for their own sake, all shared with people who, by and large, know more than I do and think differently.

Of the talks I just want to highlight one in particular, because my project also uses one of the techniques mentioned. Dieter Saur is a medical doctor and has his own lab group, which studies mainly gastrointestinal diseases, including pancreatic cancer. In a recently published paper (Schönhuber et al, 2014) they describe an experimental system in mice called the “dual recombinase system“. This is a genetic system that allows the study of complex diseases such as cancer. Until recently it was only possible to simultaneously switch on a gene that drives tumour progression and switch off a gene that prevents tumour formation in a cell type or organ of interest (e.g. in the pancreas). Using the dual recombinase system it is possible to make genetic alterations sequentially. For example, in the beginning of a mouse’s development one can activate a potent tumour driver called Ras and delete an important tumour suppressor called p53. And then, once a tumour has formed, one can additionally delete genes that may be important to maintain the established tumour. Alternatively, the dual system also makes it possible to make genetic changes to the normal cells surrounding the (pancreatic) tumour. If all goes well then I will be able to use these tools to conduct experiments like this in the next year or so.

15044797_10154563370871405_2126581266_o zip-line

Oh and admittedly we did have an activity scheduled that was slightly less scientific: we got all geared up and went on a GoApe outing. Secured by a harness and after some rigorous safety instructions we got to fly down zip lines, balance over gaping abysses and jump over the void below.


Lastly, the following week saw Queen Mary University London and Barts host the 11th UK cancer stem cell symposium. There were several interesting talks, including by group leaders at the Crick Institute, but the most unusual talk was given by a philosopher called Lucie Laplane. She did her PhD in philosophy and combined this with a research master’s in stem cell biology. Putting the two fields together she came up with a classification of (cancer) stem cells using definitions and guidelines borrowed from philosophy, applied to biology. [In general, researchers agree that stem cells are cells that can self-renew (i.e. generate new copies of themselves) and can produce differentiated/specialised daughter cells.] The most important point was how to pin down what kind of characteristic “stemness” is or what makes a stem cell a stem cell:

csc-table

Framework for defining (cancer) stem cells – copied from Lucie Laplane’s talk at the symposium

For instance, in some cases a stem cell might always be a stem cell no matter what the environment is like (i.e. categorical); other stem cells may be dispositional in nature, meaning that they always have the potential to act as a stem cell but only do so in a permissive environment. Alternatively, being a stem cell might not be property of a single cell at all but rather an attribute of an entire organ (i.e. systemic). Laplane argued that the way we define (cancer) stem cells has a huge impact on how we try to treat diseases such as cancer. For example, if cancer stem cells are “systemic” then even the best therapies targeted against these cells will fail because the system/the tumour will make new cancer stem cells from other tumour cells. Hans Clevers, one of the Gods in the stem cell field, wrote a glowing review of the book here.

References:

Laplane, Lucie. Cancer Stem Cells: Philosophy and Therapies. Harvard University Press, 2016.

Schonhuber N, Seidler B, Schuck K, Veltkamp C, Schachtler C, Zukowska M, Eser S, Feyerabend TB, Paul MC, Eser P, Klein S, Lowy AM, Banerjee R, Yang F, Lee C-L, Moding EJ, Kirsch DG, Scheideler A, Alessi DR, Varela I, Bradley A, Kind A, Schnieke AE, Rodewald H-R, Rad R, Schmid RM, Schneider G, Saur D (2014) A next-generation dual-recombinase system for time- and host-specific targeting of pancreatic cancer. Nat Med 20: 1340-1347

Not all cancer cells are equal

This is the essay I submitted to the Max Perutz Writing Award 2016.

Look at yourself in the nearest mirror and, if you aren’t too squeamish, visualise the inside of your body. It’s obvious that not all your cells are the same. We are made of many different tissues that perform different tasks: skin cells protect us from the environment, white blood cells defend us against infections, nerve cells allow us to move and think. Cancer – the uncontrolled growth of cells – can arise from virtually any type of tissue. We hear about new treatments for skin cancers, about raising money for childhood leukaemias, about inoperable brain tumours. We know that there are different types of cancer.

But an individual tumour in a tissue is also complex. Researchers realised decades ago that, like our healthy bodies, tumours aren’t simply lumps of identical cells; that within each tumour there are different cell types. For instance, some tumour cells divide indefinitely to keep the cancer alive, others invade into surrounding tissue and spread to other sites of the body, while yet others stimulate blood vessels to grow. Some cancer cells even combine several of these properties.

In our laboratory we study the pancreas, an organ of the digestive system, which aids digestion and controls metabolism throughout the body by secreting hormones such as insulin. In particular, we investigate variations among cell types in the most common kind of pancreatic cancer called pancreatic ductal adenocarcinoma (PDAC for short). PDACs are among the most deadly cancers with only about three per cent of patients diagnosed with PDAC in the UK surviving for longer than five years. One of the reasons for this gruelling statistic is that PDACs are often diagnosed late, when the cancer cells have already spread to and wreaked havoc in other internal organs. Previously, several labs, including ours, noticed that some PDAC cells are more aggressive than others, more capable of re-growing new tumours from scratch. Now, we aim to understand what makes the more aggressive PDAC cells different from the rest of the cancer cells and how they contribute to the deadliness of this cancer. With that knowledge in hand, the broader aim will be to find anti-cancer drugs to target and kill the most dangerous cells that lie at the heart of PDAC.

A previous PhD student in our lab discovered that the more aggressive PDAC cells make and display large amounts of a certain protein – let’s call it protein X – on their cell surfaces. We say that the more aggressive cells are “marked” by protein X. This realisation was my gateway into finding out exactly how these two cell types, the more and less aggressive cells, differ.

First, I wanted to know whether protein X not only marks the more aggressive cells but whether it is directly responsible for making those cells more dangerous. Therefore I experimentally reduced or elevated the levels of protein X in PDAC cells we grow in the lab. Then I assessed whether the PDAC cells grew more or fewer, larger or smaller “organoids”, miniature replicas of pancreatic tumours. Astonishingly, the cancer cells actually grew less well when I removed most of protein X, or they divided and proliferated much more when they had more of protein X. This is a good indication that, in future, drugs might be delivered directly to protein X to eliminate the aggressive cells or convert them into tamer cells.

In the meantime, I am on the lookout for other characteristics that might distinguish between the more and less aggressive cells. From one of my experiments I have data hinting that the two cell types might in fact have different physical properties. However, until I’ve repeated these experiments I can’t be certain that this difference in appearance contributes to the more aggressive cells’ behaviour. But it is thinkable, for example, that the more aggressive cells can attach to other cells or blood vessels more easily, aiding their movement to the lungs or liver. These secondary tumours, also known as metastases, are the tumours that PDAC patients usually die from. Next, I need to determine whether there is a direct connection between protein X and the variations among the physical properties of the PDAC cells.

We really want to pin down the differences between the more and less aggressive cells so that hopefully researchers and pharmaceutical companies will be able to design and develop more effective drugs to tackle PDAC. In a few years, once we know more precisely what protein X is doing in the more aggressive cells, our findings might matter a great deal to patients. For the moment I am simply trying to find out more about how PDAC cells work and I know that can sound theoretical. However, I am certain that knowing why and how some cancer cells, clearly, are more equal than others will help patients in the future.

 

Still digesting…

… the outcome of the Brexit referendum, yes. Or the fact that Austrian presidential elections need to be repeated, yes. But also, and on a more positive and scientific note, still digesting articles at eLife. It’s almost exactly a year since I did a short internship with their Features Editorial team, at the end of which my boss, Peter Rodgers, asked whether I would consider continue writing as a freelancer. Consider it? Of course. Yes, no consideration needed. I don’t think I could conceal quite how pleased I was with the offer. So for almost a year now I have been writing one digest a week (about two hours worth of work) and here I’d just like to highlight a few of the most interesting ones.

Inactivation of the ATMIN/ATM pathway protects against glioblastoma formation

This was the second paper that landed in my inbox to digest. When I read the subject line I was a bit baffled by the coincidence, because it surely had to be a coincidence. The lead author of this paper was none other than my current PhD supervisor with whom I was scheduled to start a month later.
The main finding of this paper was a little bit counter-intuitive. The first author, Sophia Blake, studied glioblastomas, the most aggressive form of brain cancer, iand found that when she deleted a tumour suppressor gene called p53 in mice, the animals developed these tumours. So far so good. However, when she deleted a second tumour suppressor called ATMIN at the same time, fewer mice got fewer and smaller tumours.  The paper then goes into some mechanistic detail of how this happens and finishes by showing that there are probably similar processes at play in human glioblastomas.

Ebola virus disease in the Democratic Republic of the Congo, 1976-2014

Most often the papers I read and digest are about cancer, stem cells or molecular biology. Here, however, I got to take a look at an epidemiology study: the authors compiled data for seven Ebola outbreaks in the Democratic Republic of the Congo. To me the most interesting observation was that outbreaks that had, at the outset, a high “reproduction number” – the number of people a single infected person transmits the disease to – were caught and contained early. However, when this reproduction number was smaller than about three the outbreaks seemed to be dealt with less quickly, leading to an overall greater negative effect.

Pericytes are progenitors for coronary artery smooth muscle

In this paper Volz et al. used fluorescent imaging to track the progression of epicardial cells (on the surface of the heart) deep into the muscle tissue of the heart. Using these microscopy techniques, the authors could follow how the epicardial cells become smooth muscle cells, cells that contract and relax, in the coronary arteries. Clicking on the image below will take you to a video consisting of snapshots taken from the outside of a mouse heart to further within. The epicardial cells first become so-called pericytes, cells that normally support blood vessels, and then eventually turn into smooth muscle cells.

pericytes

Snapshot from the first video in Volz et al.

Secretion of protein disulphide isomerase AGR2 confers tumorigenic properties

This last paper I want to mention briefly because it is on a subject that is similar to my project. Fessart et al. studied what can make lung and breast cancer cells more aggressive, more tumorigenic. They noticed that a protein called AGR2, which is normally found within cells where it helps to fold other proteins correctly, can also be secreted outside cells. When this happens AGR2 can make healthy lung cells cancerous.

Almost one year of PhD is already over, three more to go. I think we can count ourselves lucky if, by the end of it, we have a nice story to publish…

References:

Blake SM, Stricker SH, Halavach H, Poetsch AR, Cresswell G, Kelly G, Kanu N, Marino S, Luscombe NM, Pollard SM, Behrens A (2016) Inactivation of the ATMIN/ATM pathway protects against glioblastoma formation. eLife 5: e08711

Fessart D, Domblides C, Avril T, Eriksson LA, Begueret H, Pineau R, Malrieux C, Dugot-Senant N, Lucchesi C, Chevet E, Delom F (2016) Secretion of protein disulphide isomerase AGR2 confers tumorigenic properties. eLife 5: e13887

Rosello A, Mossoko M, Flasche S, Van Hoek AJ, Mbala P, Camacho A, Funk S, Kucharski A, Ilunga BK, Edmunds WJ, Piot P, Baguelin M, Muyembe Tamfum J-J (2015) Ebola virus disease in the Democratic Republic of the Congo, 1976-2014. eLife 4: e09015

Volz KS, Jacobs AH, Chen HI, Poduri A, McKay AS, Riordan DP, Kofler N, Kitajewski J, Weissman I, Red-Horse K (2015) Pericytes are progenitors for coronary artery smooth muscle. eLife 4: e10036

Cancer Research UK – PhD Student Meeting

Cancer Research UK (CRUK) is the world’s largest independent cancer charity (according to Wikipedia)  and funds thousands of scientists across the UK. In the latest annual report they state that more than £340 million were spent on research. Take a look at the fancy infographic here to see a break-down of how that money was spent:

annual report

The reason for writing this post on CRUK is that today the charity held its first-ever first year PhD students’ meeting in London, at the Quaker Friends House near Euston station. The attendees came from all over the UK: from as far afield as Aberdeen and Manchester to Oxford and Cambridge and finally us lazy Londoners who could afford to get up later than on a normal lab day.

The main aims of the meeting were to get to know some of the people working at CRUK’s head office in London and how, in future, we might apply for their funding. One of the first things I learnt today was that CRUK has made four cancer types – brain, lung, pancreatic (!) and oesophageal – “strategic priorities”, because the survival rates for these are still low and lagging behind those of, say, breast and prostate cancer. We also heard, from the senior research funding manager, Richard Oakley, how CRUK spends its money and what we can and are meant to do to help. Among other things this involves wearing branded t-shirts and participating in fundraising events. So tomorrow morning I will wear this to run in the park in preparation for the 10 km Race for Life happening at the end of June – please feel free to fund me and/or the maybe pink team and/or join the run! [We can start a separate conversation on the topic of the martial language used by CRUK, and other charities, to help raise the money. N.B. The back of the t-shirt reads, “Ask me about my life-saving research.”]

cruk

Since doing a PhD is all about the learning experience, most of the morning was filled with one of three workshops on either a) assertiveness, b) time management, or c) having an effective working relationship with your supervisor. I chose the first option, and although some people (especially in my lab) will argue that it would be better if I were a bit more quiet on occasion, I thought it would be interesting to see what it could offer. The basic message was, of course, quite clear: effectively communicate your needs whilst appreciating other people’s needs. Easier said than done for sure. The only thing that helps is practising being in potentially awkward situations and putting oneself outside one’s comfort zone, which is where learning can happen. Possibly the most helpful information was to realise what isn’t assertive behaviour (e.g. being too passive, or too (indirectly) aggressive) and making sure to recognise those behaviours in oneself and learning to avoid them in future. We’ll see how that goes.

Over lunch we got to browse a few posters. I particularly enjoyed the ones on intestinal stem cells and a potential preventative treatment for breast cancer using the diabetes drug Metformin. And lastly, we were politely, with the help of beer and/or wine, coerced into networking…

First PhD Checkpoint

In December, we – the (mostly) young and innocent first-year PhD students at the Francis Crick Institute – gave our first formal talks. Each student had to present the outline of their project to all the other students in a ten minute slot. This was probably intended mostly for our own benefit to ensure that we had at least a rough idea of what we will be working on for the foreseeable future. Here I’d just like to mention a few of the talks that I found particularly interesting, but it’s worth saying that I thought the overall level of presentations was very high and the questions we ended up asking each other were well thought through. Overall a very enjoyable experience.

  1. To begin with there were a couple of talks from students in the same lab studying the interactions of cancerous cells with the immune system. In particular, they are trying to find out how dendritic cells – cells that normally alert effector cells of the immune system that something is wrong (e.g. an infection is happening) – can sense the presence of dead/dying tumour cells and relay this information to so-called T cells. The two students are looking at both the molecular mechanism by which this happens, but also whether precursors of dendritic cells in the bone marrow have similar abilities.

  2. A few students in the programme are working on mathematical/computational projects and will never have to wear a lab coat. For example, one lab is interested in understanding how non-cancerous cells near a tumour interact with the cancer cells and influence their ability to move. To do this one can mathematically model the movement patterns of the “cancer-associated fibroblasts” and how they interact with extracellular proteins to form tracks for the cancer cells to move along. In the simplest terms (and that’s the only level at which I understand this), the model relies on the Morse potential, which is normally used to understand how atoms interact but can be scaled up to model interacting cells. Here is a video of a fibroblast interacting with a breast cancer cell; the accompanying text is maybe overly simplistic, but you get the gist:

    Another student is studying how sheets of cells move together, both during embryonic development and tumour formation. This relies (roughly) on modelling cells as polygonal shapes that stick together via their vertices. Yet another “dry” project is investigating how cancers evolve over their lifetime: this is done by collecting DNA sequencing data from cancer cells at various stages of their development and inferring which changes happened when.

  3. Since it is generally the metastases that are the deadly part of cancers it is important to  understand how cells move. There is, of course, a lot of information about this already but here the aim is to find out more about how different cancer cells (e.g. breast cancer and skin cancer) share certain features in their movement patterns.

  4. Not all labs in the institute study cancer. Some labs focus on basic research using yeast as a model organism. Both yeast cells and our cells contain a lot of DNA that is not translated into protein; for a long time all this DNA was termed “junk” and nobody bothered with it too much. It is becoming increasingly clear that this so-called non-coding DNA can still play various roles in the cell and some of these may be deleterious. Therefore one student is studying how cells prevent the activation (transcription) of some of these stretches of DNA.

  5. Another major branch of the institute deals with infectious diseases and the immune system more broadly. Two talks that I enjoyed on this front were given by students again working in the same lab. They are studying “neutrophil extracellular traps” (NETs), which I had never heard of before and sound quite cool. Neutrophils are a cell type of the immune system and are the first to react to infectious agents. By releasing very broad-acting antimicrobials they try to quell an infection in its infancy, but by doing so they also cause the four main symptoms of inflammation: pain, heat, redness and swelling. NETs are made of DNA and proteins from the neutrophils and are sticky. One of the students is looking into how NETs can exacerbate atherosclerosis, while the other is finding out how NETs physically trap invaders, such as the fungus Candida albicans.

  6. Lastly, and because it would pain me not to mention CRISPR, one student is trying to find a way to control the sex ratio of offspring in laboratory animals, specifically mice. While at first glance this might seem dangerous or cruel, it is actually part of an effort to reduce, replace and refine the use of animals in research. For example, if you are studying prostate cancer or ovarian cancer half of the experimental animals born are completely useless and end up being “wasted”. At the moment, some agriculture relies on physically sorting sperm cells into those carrying X or Y chromosomes and using mainly those with X chromosomes for in vitro fertilisation (because far fewer male animals are needed). Although this is a very accurate method it is expensive and time-consuming. Since CRISPR is precise and can be genetically encoded it would virtually work by itself once established.

This is by no means an exhaustive list of the topics covered by our projects, but hopefully it’s an interesting glimpse into what we are currently spending (almost all?) of our brains and energy trying to figure out.

These talks will be complemented with a so-called thesis committee meeting later this month: here each student will present a very similar talk to three professors or group leaders, who will be advising the project from an outside perspective. Hopefully being locked in with three clever and knowledgeable people will conjure up constructive criticism as well as (even more) new ideas!