Cyclin-Dependent Kinase (CDK)9 in pancreatic cancer: role for tumor progression, metastasis and chemoresistance of pancreatic and evaluation of novel TRAIL-/CDK9-inhibitory-based therapies

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Prognosis of pancreatic cancer is extremely poor due to invasive growth and early metastasis. Moreover, pancreatic cancer cells are widely resistant to chemotherapy. To improve the outcome of pancreatic cancer patients, the malignant characteristics of this tumor entity has to elucidate to subsequently envisage novel and highly effective anti-cancer therapies. Recently, we identified Cyclin-dependent kinase (CDK)9 being overexpressed in pancreatic cancer tissue. Moreover, high CDK9 expression was associated with impaired survival. Interestingly, selective CDK9-inhibition suppressed the growth of pancreatic cancer cells and augmented the effect of chemotherapeutic agents. Moreover, we identified selective CDK9-inhibtion as an extremely potent strategy to sensitize cancer cells, but not normal cells, to TNF related apoptosis inducing ligand (TRAIL)-induced apoptosis. In our proposal we set out to investigate the role of CDK9 for tumor progression, metastases and chemoresistance of pancreatic cancer and to decode underlying molecular mechanism. To achieve this pancreatic cancer cells with inducible CDK9-shRNA and CDK9-overexpression will be generated and characterized in terms of proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) in vitro as well as tumor growth, metastasis and chemoresistance in vivo. To uncover underlying molecular mechanisms RT-PCR, immunohistochemistry, western blotting, BH3-profiling and well as gen-expression profiling will be performed. In addition, an orthotopic patient derived xenograft (PDX) mouse model will be used. In this model, small pieces of human tumor tissue with surrounding stroma tissue will be implanted subcutaneously in NOD scid gamma mice directly upon surgical resection. After tumor establishment the tissue will be amplified over 2-4 mouse generations to generate sufficient amount of tumor tissue to be able to surgically implant tumors orthotopically in enough mice required for the treatment groups. In this model the novel combination of the CDK9-inhihitor Dinaciclib and TRAIL will be tested. The tumor size and metastases will be quantified by mouse MRI and histopathological analysis. Moreover, primary cell lines will be established from these tumors and subsequently characterized. Utilizing above described techniques, mechanisms of resistance will be characterized, in order to pharmacologically overcome or preempt resistance to this therapy. Hereby, we set out to establish a novel and highly effective therapeutic strategy for pancreatic cancer.