The Oncogenic functions of YAP/TAZ in Renal Cell Carcinoma - PROJECT ABSTRACT Renal cell carcinoma (RCC) is the 8th most common form of adult cancer in the US. Despite recent improvement in treatment options, the majority of patients with metastatic RCC continue to succumb to this disease, resulting in over 100,000 deaths per year worldwide. Thus, it is important to identify novel therapeutic strategies to more effectively treat this deadly disease. My preliminary studies suggest that YAP/TAZ function as master regulators of the core oncogenic transcriptional network and are required for maintaining the transcriptional homeostasis of RCC tumors. The first major aim of my proposal is to determine the effects of pharmacologic and genetic inhibition of YAP/TAZ on oncogenic transcription and super enhancer maintenance in patient-derived primary RCC cells. I will employ cutting-edge epigenomic techniques including Cut&Tag and QuantSeq to probe how genetic and pharmacological inhibition of YAP/TAZ affects the compositions and activities of the YAP/TAZ transcriptional complexes and the global RCC epigenetic and transcriptional landscape. Given the reported functions of YAP/TAZ in orchestrating phase-separated transcriptional condensates at super enhancers, I will combine immunofluorescence analysis of endogenous YAP/TAZ and other components of the YAP/TAZ transcriptional complexes, along with DNA fluorescent in situ hybridization (DNA-FISH) against YAP/TAZ-bound enhancer regions, to investigate how genetic or pharmacological inhibition of YAP/TAZ affects the formation of active transcriptional condensates at these particular genetic elements and their necessity in regulating YAP/TAZ target genes. Through these analyses, I will be able to gain critical insights into the molecular functions of YAP/TAZ in RCC tumors, but also reconstruct the core ensemble of the RCC oncogenic transcriptional network. The second major aim of this proposal is to determine how YAP/TAZ functionally interacts with hypoxia-inducible factor 2 alpha (HIF2A) and whether YAP/TAZ co- inhibition can overcome resistance to HIF2A inhibitors in an in vivo model. While HIF2A inhibitors are in late stage clinical trials, upfront and acquired resistance to this small molecule inhibitor is prevalent. My preliminary findings suggest that YAP/TAZ signaling may contribute to resistance to HIF2A inhibitors. Using pharmacological inhibitors of YAP/TAZ and HIF2A, I intend to use Cut&Tag and QuantSeq to investigate the functional interactions between HIF2A and YAP/TAZ in maintaining clear cell RCC oncogenic transcription, as well as possible YAP/TAZ regulated genes mediating resistance to HIF2A inhibitors. Furthermore, I will investigate how YAP/TAZ inhibitors, in combination with HIF2A inhibitors, impact the in vivo growth of HIF2A-i- resistant patient-derived ccRCC xenografts, performing QuantSeq on harvested tumors to validate my in vitro findings. Together, these studies will greatly enhance our understanding of the crosstalk and redundancies between the oncogenic pathways that govern the growth and survival of RCC cells, potentially yielding more effective combination strategies to overcome treatment resistance in RCC patients.
