The ChadTough Foundation and Michael Mosier Defeat DIPG Foundation have partnered to fund more than $3.3 million in Diffuse Intrinsic Pontine Glioma (DIPG) research grants. Their first round of grants was announced in 2017 and included a fellowship grant awarded to Dr. Jamie Anastas, a research fellow at Harvard University and Boston Children’s Hospital.
Dr. Anastas was awarded a Defeat DIPG ChadTough fellowship grant for her study, “Targeting chromatin regulation to treat DIPG.” The study looks at how the histone mutation commonly found in DIPG affects how the tumor cells function.
Dr. Anastas spoke with the Defeat DIPG and ChadTough team to provide an update on this project:
Q: Can you provide an overview of your project?
Dr. Jamie Anastas: “Sure! I’m currently working as a postdoc in Yang Shi’s lab at Boston Children’s Hospital where we study epigenetics, which is essentially a field where we look for factors that can lead to changes in cellular behaviors and gene expression but don’t involve changes in the DNA sequence. So one of the main things that we’re focused on are proteins called histones, which help to control which genes are turned on and off in both normal cells and tumor cells. Histones are really interesting in the context of DIPG because the majority of DIPG tumors produce a mutant version of one of these histone proteins which can then go on to disrupt gene regulation. I’m studying various pathways that regulate the ability of histones and other factors to control cell behaviors to try to figure out if any of those pathways might be targeted in DIPG. Hopefully we can develop new therapies for DIPG and understand a little bit more about the basic biology of this disease.”
Q: Your project says you screened 1,300 regulators in an effort to narrow it down to see which aided in DIPG survival. Are there any results of anything you can share?
Dr. Jamie Anastas: “We don’t have the final answer yet, but I can speak more generally about the method we’re using to try and narrow down pathways. Like you said, we did a screen for around 1,300 different chromatin factors. To do this, we grew up a bunch of DIPG cells and used a relatively new technology called CRISPR Cas9 where we use a bacterial enzyme to induce cuts or disruptions in the sequence of these genes to block their function. Instead of inhibiting one factor at a time, we used a pooled approach where we were able to look at conditions that disrupt the function of all these genes at once in one big experiment. After getting a list of potential hits from the screen, there have been a lot of validation steps. Although we only did the screen initially in two cell lines, we’ve now expanded to many more patient cell lines through collaboration with Mariella Filbin’s and Todd Golub’s groups.
“The first thing we were able to do was look for hits that were coming across in a majority of the cell lines. We then had to validate the hits in individual cell lines, ensuring that the tools we were using to disrupt these genes really led to the changes we expected. The gene-targeting libraries we used to do the screen were based on a bioinformatic approach, but we still had to actually look at the cells and make sure that the genes were mutated or that the protein encoded by them was lost. We’ve been able to do that for a subset of the screen hits. Another important thing was to see whether disrupting these genes can also affect the growth of normal cells. While it’s not completely essential that disrupting these genes only kills DIPG cells, it’s of course nice if they’re at least more sensitive. When thinking about eventually developing a drug to one of these pathways, we wouldn’t want it to hurt normal tissues.”
Q: What is the next step in the process after completing a project like this, in the grand scope of DIPG?
Dr. Jamie Anastas: “Ideally, once you’re really confident that a certain pathway is important for DIPG growth — including in mouse models, which is something we’re still working on — we would want to then identify a drug or some other therapeutic intervention that can either directly or indirectly affect that pathway. This might involve repurposing already existing drugs, or, in some cases, it might involve trying to generate entirely new compounds or strategies. I think in the context of DIPG, a lot of the pre-existing drugs just haven’t been effective, so I think we need to be open minded about identifying new targets and hopefully continue to work on ways to activate or inhibit them.”
Q: Can you talk about your professional background and how you got to be here doing the study?
Dr. Jamie Anastas: “I went to graduate school at the University of Washington where I was also working on cancer but not working in epigenetics. I was working on secreted molecules called WNTs that can activate various signaling pathways. Somewhere during that process I got really interested in epigenetics and gene regulation, so I went on to contact various labs so that during my postdoc work I would learn about chromatin and epigenetics and genomics and all of these sort of things. I ended up joining the Shi lab, and, at the time I was interviewing in the lab for the postdoc position, papers finding mutations in histone proteins in DIPG and other tumors had just come out.
“I remember talking to Yang saying that this was really cool, that we should study this, and we should find a way to understand the epigenetic drivers of this disease. It’s been challenging in some ways because the lab I’m in really focuses on the basic molecular biology of chromatin. It’s not a brain tumor lab. So I’ve been really fortunate to have had lots of support from other researchers, Mariella Filbin in particular who’s a neuro oncologist is closely collaborating with us on various projects, other DIPG groups, like Michelle Monje’s, Nada Jabado’s, Keith Ligon’s and Suzanne Baker’s labs have generously given us cell lines and protocols. I think it’s pretty exciting to have a chance to take this knowledge of molecular biology and biochemistry and do our best to apply it to a really terrible disease and a really challenging problem.”
Q: Do you plan to continue focusing on DIPG once this study is complete?
Dr. Jamie Anastas: “Long term, I’m certainly interested in exploring other mechanisms driving DIPG tumorigenesis. I have a previous background in signaling, so the obvious next steps now that I’ve screened through these different chromatin factors would be to expand to look at how different systems might regulate DIPG growth – signaling or otherwise. It’s definitely something that I’m interested in, it’s just a matter of having the time and personnel to go through those experiments. From a practical point of view — since I’m doing my postdoc in an epigenetics lab where we’ve got all of the tools and expertise in that area — it makes sense for me to focus on the lab’s strengths for now.
It is also pretty clear that one drug or one intervention like radiation is probably not going to work in DIPG, so being able to understand how different pathways and processes might interact to drive tumorigenesis might be really key to eventually finding treatments that work. Beyond that, these tumors are, of course, not identical even though the majority of them have mutant histones. There’s a lot of heterogeneity, in terms of differences in genetic mutations and potentially in epigenetic regulation. So we may need to look at a variety of targets or pathways to find treatments that may be tailored to individual patients.”
Q: How will this fellowship allow you to advance your career?
Dr. Jamie Anastas: “This fellowship will help my career by giving me the opportunity to pursue more mechanistic lines of research to determine how chromatin regulators might drive DIPG tumorigenesis, which will allow me to learn and develop methods for studying brain tumors more generally. Hopefully, the skills and knowledge gained while supported by the ChadTough and Defeat DIPG foundations will help me prepare to lead a research group focused on understanding the molecular biology of pediatric brain tumors.”