Early Career Innovators: Therapeutic Vulnerabilities of an Oncoprotein in Tumour Initiation, Small Molecules TIN

In the next Small Molecules TIN interview as part of the Early Career Innovators series, acknowledging the amazing translational work being done by early career researchers within the UCL Therapeutic Innovation Networks (TINs), Dr Victor Llombart highlights his Small Molecules TIN Pilot Data Fund awarded project, “Identifying therapeutic vulnerabilities of MYC through next generation structure-function”.

What is the title of your project and what does it involve?

My project is titled “Identifying therapeutic vulnerabilities of MYC through next generation structure-function”. MYC is an important oncoprotein involved in tumour initiation and development that is difficult to target using conventional small molecule-based approaches. The main reason is that MYC conforms a structurally highly disordered protein from which is virtually impossible to obtain a crystal model unless it is forming a complex with other proteins that stabilize it. Consequently, the design of drugs based on structure models of MYC is extremely challenging. Alternatively, we have designed and generated a library of MYC mutants to identify new protein domains that are potentially “druggable”. This pooled library can be screened using our MYC-dependent cell line allowing the identification by next generation sequencing of those aminoacid residues that are crucial for MYC oncogenicity.

What is the motivation behind your project/therapeutic?

Cancer is a major public health and economic issue worldwide. In the UK, ≈1,000 new cases of cancer are diagnosed every single day and most of the current anti-cancer therapies present high toxicity, drug resistance and significant side effects.

The protein MYC is an essential global transcription factor that regulates important functions in our body such as cell growth, cell metabolism or blood vessel development. MYC is also one of the most frequently altered genes in cancer and its expression is deregulated in about 70% of all malignancies. Several studies in animal models have shown how MYC inhibition leads to a rapid tumour regression while the healthy tissue remains unaffected. This opens the way for new therapies and makes MYC one of the most appealing targets for cancer treatment. However, as I mentioned before, the design of small molecules that target MYC is challenging. Our approach overcomes these limitations allowing an unbiased functional analysis at single amino acid resolution that I believe will provide essential structure-function information. Our data will also allow the identification of critical MYC interactors that can be explored for the indirect inhibition of MYC and form the foundations of a small molecule drug screening platform.

Why did you want to apply to the Small Molecules TIN Pilot Data Fund?

As an early-stage researcher, The Small Molecules TIN Pilot Data Fund was my first opportunity to apply for a grant as the main applicant. I thought that, if successful, it would be an excellent opportunity to manage my own research funds.

Also, I felt that the preliminary results of our MYC mutants library screening were extremely promising but made us realize that an increased sequencing depth was required in order to reach single aminoacid resolution. I was convinced that our proof-of-principle experiments were suitable for applying to the Small Molecules TIN Pilot Data Fund and that the scheme would be perfect to fund the additional sequencing analyses that are needed.

How did you find the process for the TIN Pilot Data Fund? What did you learn?

The application process was very quick. After submitting my application with all the relevant details of the project, my proposal was shortlisted for a pitch with a panel of experts following a Dragons’ Den style event. This was the first opportunity I had to defend my project in such format and it was extremely challenging, mainly for the short time we were given to present our data. Before the pitch, I learned how to present complex scientific data succinctly to specialists from industry and academia with very different backgrounds. As part of the ACCELERATE program I attended a training session that helped me to deliver an impactful and convincing message. In this workshop, I also received useful advice about how to navigate through the long Q&A and how to improve my body language – which is important also in an on-line session over COVID times! My lab mates helped me too by improving my presentation and by anticipating the most probable questions – they are absolutely amazing! During the whole process, I received important feedback from different perspectives that will definitely improve the project. Overall, I consider it a very positive experience that helped me to strengthen future grant proposals.

What do you hope to achieve in the 6 months duration of your project?

My plan at the end of this period is to reach an appropriate sequencing depth after the screening of our library in an adequate number of biological replicates generating a complete functional map of MYC. This will allow a robust statistical comparison and will decrease the number of false positives, ultimately reducing the costs derived from subsequent validation steps that we will carry out.

What are your next steps from now?

I will start by generating large-scale cultures of the MYC-dependent T-ALL cell line used as a model in this screening. These cells will be transfected with our MYC mutant library ensuring a proper representation of all the variants during the process and they will finally be incubated with tetracycline. During this incubation, those variants that translate to a non-functional MYC protein will drop out and will be identified by NGS and validated individually. These results will allow the identification of domains in the MYC protein that are critical for its oncogenicity. Following a mass spectrometry-based approach, we will try to identify novel MYC co-factors that are essential for its function and interact with MYC through these critical domains. We anticipate that this data will enable us to delineate in future proposals the structure of the protein-protein interaction interfaces that will ultimately inform in in silico drug design.

About Dr Victor Llombart

Dr Victor Llombart is a molecular and cellular biologist that works as a Post Doctoral Research Associate in the lab led by Dr Marc Mansour, at the Haematology Department of the UCL Cancer Institute. Dr Llombart’s main research interest is learning how proteins that are involved in key biological processes function, interact and regulate essential tasks within the cell. During his PhD at Universitat Autonoma de Barcelona he developed different proteomic approaches for the discovery of novel diagnostic biomarkers for stroke using different in-vivo and in-vitro models as well as human samples.

Later, at St George’s University of London he worked on understanding the mechanisms that regulate the trafficking and exocytosis of intraluminal vesicles in endothelial cells.

Dr Llombart joined UCL in 2018 on a CRUK-funded project aiming to identify novel domains of the oncoprotein MYC that are important in protein-protein interactions and can potentially be targeted using small molecule drugs.