Mechanism of action of the SETD5 protein methyltransferase in pancreatic ductal adenocarcinoma.

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Pancreatic cancer is a devastating disease and despite intensive research during the last 30 years, the 5-year survival rate of pancreatic cancer remains constantly low. This is primarily due to the late diagnosis and due to ineffective therapy options. While targeted therapies directed against kinases of the Ras signaling pathway have shown promising effects in vitro and in vivo they remained largely ineffective in clinical trials due to high toxicity, low efficacy and development of therapy resistance. Lysine methyltransferases (KMTs), which perform posttranslational modifications, have emerged as potential key regulators of cancer pathways. In comparison to enzymes like protein kinases that have well-established roles in tumorigenesis, the mechanisms by which KMTs enzymes contribute to cancer are poorly understood.The overall goal of the study is to elucidate the biological function of a newly identified methyltransferase (SETD5) in pancreatic carcinogenesis and to develop a new combination therapy that shows synergistic effects that will result in lower doses of drugs, better tolerance and reduced therapy resistance. First, I will analyze the role of SETD5 in cancer initiation and progression of precancerous lesions in an established mouse model of pancreatic cancer. Next, the function of SETD5 in tumor maintenance will be assessed. I will delete or overexpress SETD5 in KRAS mutant pancreatic cancer cell lines and analyze if SETD5 impacts proliferation, cell death, migration, invasion or metastatic spread. Using an innovative mouse model in which SetD5 will be deleted when pancreatic tumors have already developed, I will investigate the function of SETD5 in cancer maintenance in vivo. Survival and tumor burden as well as analysis of the tissue will demonstrate if SETD5 ablation results in a beneficial phenotype in these mice. Synergistic effects of a MEK1/2 and SETD5 combination therapy will be analyzed in vivo. These experiments will reveal if SETD5 has a clinically relevant function and if patients who already have developed pancreatic cancer would benefit from inhibiting SETD5. To find SETD5 targets and elucidate its biological function, I will perform a Histone Peptide Microarray followed by in vitro methyltransferase assays. RNA sequencing as well as chromatin IP will reveal which genes are differentially regulated upon SETD5 loss and which promoter regions are affected by SETD5 binding. Subsequent genome editing using the CRISPR/Cas9 technique will be used to validate the biological significance of the identified SETD5 targets. These findings will provide new knowledge of SETD5 function and will allow to analyze SETD5 targets quickly in vivo. This study will provide substantial new insights into the role of methyltransferases in the development and therapy of pancreatic cancer and might help to identify new promising candidate therapeutic targets. Thereby, this study will strongly advance the fields of cancer biology and signaling.