Delineating Novel Molecular Pathways Critical for the Growth of GNAQ/11-Mutant Uveal Melanoma Cells
Abstract
This proposal is directed towards the Focus Area of delineating molecular pathways that influence metastatic spread, with an emphasis on understanding mechanisms that enable the outgrowth of recurrent, metastatic uveal melanoma. The proposal responds to the Challenge Statement goal of investing in research studies that are focused on progression of rare melanoma subtypes. The Melanoma Research Program encourages research on rare melanoma subtypes across the spectrum from initiation to distant metastases. In that regard, it has been established that the major molecular pathway that gives rise to 90% of uveal melanomas – a pathway driven by mutations in one of two genes, GNAQ or GNA11– is still required in metastatic uveal melanomas that recur years after the original cancer was discovered. In a sense, metastatic uveal melanoma can be viewed as remaining addicted to the oncogenic signaling pathway driven by the mutant GNAQ or GNA11 proteins that gave rise to the original tumor. Therefore, if we could find a way to shut down this pathway-gone-awry in uveal melanoma cells, it should be an effective treatment for cancers that recur even years after the initial diagnosis. So far, however, attempts to shut off the GNAQ/GNA11 pathway in uveal melanoma cells have met with limited success. In our proposal, we are looking for ways to expand the range of potential strategies to inhibit this pathway, by identifying more of the key players and figuring out which of them interact with which to drive malignant cell behaviors. Our approach to this problem is to experimentally shut off the mutant GNAQ/GNA11 proteins using an inhibitor that is a useful research tool, but which itself may never be a useful drug in the clinic. This would normally result in either blocking the ability of uveal melanoma cells to proliferate, or killing them outright. However, in con- junction with blocking GNAQ/GNA11, we will also randomly switch on a large fraction of all the genes in the human genome, and then look for genes that are able to compensate for the loss of GNAQ/GNA11 function, allowing the tumor cells to survive in the presence of the GNAQ/GNA11 inhibitor. Some of these survival genes probably collaborate with GNAQ/GNA11 to promote the malignant behavior of uveal melanoma cells, and some of them may be better drug targets than GNAQ/GNA11 themselves. Two important classes of collaborators with GNAQ/GNA11 have already been identified by previous research, (i) proteins called PKC-delta/PKC-epsilon, and (ii) a protein called MEK. Inhibitors of PKC-delta/epsilon and MEK have been used in recent clinical trials, but it appears likely that additional strategies may be required for treating metastatic uveal melanoma. Therefore, we will also use a similar strategy to experimentally shut off PKC-delta/epsilon and MEK with drugs that inhibit their function, while randomly switching on genes that can promote drug resistance. This is expected to identify additional genes that can promote resistance to some of the most promising new therapeutic strategies for uveal melanoma. In conjunction with this basic experimental approach, we have also developed the ability to perform a technique called single-cell DNA sequencing. This powerful approach allows us to see how multiple genes we experimentally switch on in individual tumor cells can collaborate to promote uveal melanoma cell survival, proliferation, and drug resistance. If tumor-promoting genes are analogous to criminals, our single-cell sequencing approach is similar to a wiretap that will allow us to identify which criminals are talking to which, and thereby help us develop strategies to bring down the whole network. Our ability to couple single-cell DNA sequencing to our ability to randomly switch on most of the genes in the human genome (i.e., activating all the possible criminals) is one of the most innovative aspects of the research project we are proposing here. It involves not
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 28, 2022
- Source ID
- W81XWH2210782
Entities
People
- Christopher S. Stipp
Organizations
- United States Army
- University of Iowa