Ovarian tumour growth is characterized by mevalonate pathway gene signature in an orthotopic, syngeneic model of epithelial ovarian cancer
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James B. Greenaway1, Carl Virtanen2, Kata Osz1, Tamas Revay1, Daniel Hardy3, Trevor Shepherd4, Gabriel DiMattia4, Jim Petrik5
1Department of Biomedical Sciences, University of Guelph, Guelph, ON, N1G 2W1, Canada
2Princess Margaret Genomics Centre, University Health Network, Toronto, ON, M5G 1L7, Canada
3Department of Ob/Gyn and Physiology and Pharmacology, Children’s Health Research Institute, Western University, London, ON, N6A 5C1, Canada
4Department of Ob/Gyn and Oncology, Anatomy and Cell Biology, London Regional Cancer Program, Western University, London, ON, N6A 4L6, Canada
5Department of Biomedical Sciences, University of Guelph, Guelph, ON, N1G 2W1, Canada
Jim Petrik, email: [email protected]ca
Keywords: ovarian cancer, mevalonate pathway, simvastatin, p53
Received: January 12, 2016 Accepted: June 04, 2016 Published: June 17, 2016
Epithelial ovarian cancer (EOC) is the most lethal gynecological cancer and often is not detected until late stages when cancer cells transcoelomically metastasize to the abdomen and typically become resistant to therapy resulting in very low survival rates. We utilize an orthotopic, syngeneic mouse model to study late stage disease and have discovered that the tumor cells within the abdominal ascites are irreversibly re-programmed, with an increased tumorigenicity and resistance to apoptosis. The goal of this study was to characterize the reprogramming that occurred in the aggressive ascites-derived cells (28-2 cells) compared to the original cell line used for tumor induction (ID8 cells). Microarray experiments showed that the majority of genes upregulated in the 28-2 cells belonged to the mevalonate pathway, which is involved in cholesterol biosynthesis, protein prenylation, and activation of small GTPases. Upregulation of mevalonate appeared to be associated with the acquisition of a p53 mutation in the ascites-derived cells. Treatment with simvastatin to inhibit HMG CoA reductase, the rate limiting enzyme of this pathway, induced apoptosis in the 28-2 cell line. Rescue experiments revealed that mevalonate, but not cholesterol, could inhibit the simvastatin-mediated effects. In vivo, daily intraperitoneal simvastatin treatment significantly regressed advanced stage disease and induced death of metastatic tumor cells. These data suggest that ovarian cancer cells become reprogrammed, with genetic mutations, and upregulation of the mevalonate pathway, which facilitates the development of advanced stage disease. The use of statins to inhibit HMGCR may provide novel therapeutic opportunities for the treatment of advanced stage EOC.
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