H. Aoki1, A. Raza1, P. Mukhopadhyay1, K. P. Terracina1, C. C. Barnett3, S. Spiegel2, K. Takabe1,2 1Virginia Commonwealth University,Surgery,Richmond, VA, USA 2Virginia Commonwealth University,Biochemistry And Molecular Biology,Richmond, VA, USA 3University Of Colorado Denver,Surgery,Aurora, CO, USA
Introduction: Pancreatic cancer remains one of the deadliest cancer. Despite the recent improvement of survival of the small resectable tumors, prognosis of unresectable pancreatic cancer that collectively represent over 80% of individuals remains dismal with the 5-year survival of 5% and median survival is within ten months. Prognosis of patients with peritoneal carcinomatosis (PC), dissemination of cancer cells throughout the abdominal cavity, are particularly poor with median survival of only 6 weeks. This poor overall 5-year survival rate has not significantly changed over the past 5 decades, which reflects the fact that there is no effective treatment available for this condition. Sphingosine-1-phosphate (S1P), a bioactive lipid mediator produced by sphingosine kinase 1 (SphK1), plays critical roles in many aspects of cancer progression, such as cell proliferation, migration, angiogenesis and lymphangiogenesis. We have published in Cancer Cell 2013 that S1P link inflammation and cancer in colitis-associated cancer development. Given the fact that inflammation is known to be essential for establishment and progression of PC, where cancer cells need to adhere to the peritoneum and form a nodule, we hypothesized that S1P generated by SphK1 in the host animal, including peritoneum, is necessary for progression of pancreatic cancer PC.
Methods: Panc02 cells were obtained from ATCC. Panc02-luc cells were provided in collaboration with CCB. PC models were generated by injecting the cells intraperitonealy to C57Blk6 mice. For the orthotopic model, Panc02-luc cells were implanted in the tail of the pancreas mixed in matrigel. Survival was assessed by Kaplan-Meier method. Progression of Panc02-luc cell PC in either SphK1 wild type (WT) or knockout (KO) mice were assessed by the total tumor burden determined by bioluminescence on the indicated days.
Results: Panc02 cells developed significantly less PC by intraperitoneal injections (5 out of 11 animals with less amount of nodules). On the other hand, 96% of mice developed PC when Panc02-luc cells were injected (52 out of 54 mice with more than four-fold increased amount of nodules). The median survival of Panc02-luc PC model was 18.7 days, whereas orthotopic model was 40 days, despite the fact that 7 out of 10 orthotopically implanted animals eventually developed PC. This mimics human pancreatic cancer progression that PC has remarkably shorter survival. Panc02-luc PC in SphK1 WT mice continue to progress with significant increase in tumor burden quantified by bioluminescence, whereas PC in SphK1 KO mice did not progress.
Conclusion: Our result demonstrated that intraperitoneal injection of Panc02-luc cells in C57Blk6 mice will generate orthotopic pancreatic cancer peritoneal carcinomatosis model that mimic human disease, and SphK1 expression in the host animal, including peritoneum, is necessary for progression of pancreatic cancer PC.