Pancreatic ductal adenocarcinoma (PDAC) is the 3rd leading cause of cancer-related mortality in the United States. PDAC is the deadliest cancer, with an abysmal 5-year survival rate of 8%. Over 95% of PDAC harbor a mutationally activated KRAS oncogene, a well-validated driver of PDAC growth. Despite the near-universal dependence of PDAC on oncogenic KRAS, the development of clinically effective anti-KRAS therapies for PDAC remains elusive. One promising approach involves inhibition of KRAS effector signaling, particularly inhibitors of the RAF-MEK-ERK mitogen-activated protein kinase (MAPK) cascade. However, I hypothesize that additional kinases must also contribute to KRAS-driven PDAC growth. To address this possibility, we applied an unbiased kinome-wide chemical proteomics strategy (MIB-MS) to identify novel KRAS-regulated kinases. Upon acute KRAS suppression, we identified both upregulated and downregulated kinases. Partnering this dataset with my analyses of an RNA-Seq dataset profiling the ERK-dependent transcriptome that identified DNA-damage response (DDR) and cell-cycle regulation gene signatures, I selected the WEE1 DNA damage checkpoint kinase for further evaluation. My preliminary results determined that mutant KRAS may regulate WEE1 activity through both gene transcription and increased protein stability. I also found that pharmacologic inhibition of WEE1 suppressed PDAC growth in vitro, but additionally observed ERK activation upon WEE1 inhibition. Speculating that this ERK activation is a compensatory mechanism that can drive drug resistance, I found that concurrent ERK and WEE1 inhibition synergistically suppressed PDAC growth in vitro. These results provide the foundation for my studies and the rationale for my two aims: (1) to delineate the mechanisms by which KRAS regulates WEE1 expression/abundance and determine how WEE1 loss contributes to KRAS-dependent PDAC growth; and, (2) to apply advanced preclinical models of PDAC (organoids and syngeneic orthotopic tumors) to assess the therapeutic impact of the clinical candidate WEE1 inhibitor adavosertib, alone or in combination with the clinical candidate ERK inhibitor ulixertinitib. The scientific innovation of my studies involves exploiting DNA checkpoint inhibitors as a therapeutic vulnerability of KRAS-mutant pancreatic cancer, where current standard of care remains ineffective conventional cytotoxic drugs. My studies will further elucidate basic mechanisms of KRAS signaling and additionally identify new therapies for clinical evaluation. This research will provide me with training in cancer cell and molecular biology, preclinical drug assessment, and the implementation of computational tools for bioinformatics analyses. I will also participate in mentored clinical activities focused on the care of a diverse set of oncology patients. Overall, the superior research and clinical opportunities at the University of North Carolina at Chapel Hill, my network of experienced collaborators within the Lineberger Comprehensive Cancer Center, and the exceptional mentoring of Dr. Channing Der will propel and prepare me to become a leading physician-scientist in cancer biology.
Pancreatic cancer is a devastating disease that will soon be the 2nd leading cause of cancer mortality in the United States. While the genetic drivers of pancreatic cancer have been well-studied, poorly effective chemotherapy remains the only treatment option for most patients. This proposed study will characterize and validate a promising therapeutic target in pancreatic cancer, WEE1 tyrosine kinase, and the results of this work will establish a novel targeted therapy to ultimately improve the outcomes of pancreatic cancer patients.
