Abstract Ovarian cancer metastasis occurs when malignant cells migrate from the primary tumor into the ascitic fluid and form a secondary tumor in the peritoneal cavity. The cells responsible for this process, Metastases Initiating Cells (MICs), suffer a series of changes in protein expression, with increased Epithelial Mesenquimal Transition and stem cell markers having been reported. Tissue Factor Pathway Inibitor-2 (TFPI-2) is a serine proteinase inhibitor and potential tumor suppressor gene, whose reduction is correlated with more metastases and poor prognosis. As the exact stage of TFPI-2 loss is still unknown, the purpose of our study was to determine TFPI-2 during ovarian cancer progression. Protein and RNA levels were assessed in primary tumor and metastatic tissue from papillary serous carcinoma by immunohistochemistry and qPCR, respectively. TFPI-2 RNA and protein levels were analyzed in cancer cell lines and primary cultured cancer cells isolated from ascitic fluid of advanced ovarian cancer patients and in cancer spheres derived from these cultures. Epigenetic changes of 3 CpG were analized by bisulfite and pirosequencing technique in ovarian cancer cell lines and in cancer spheres derived from these cultures. We report that significantly decreased TFPI-2 protein levels in metastatic tissue compared to the primary tumor, a result confirmed in matched primary and metastatic lesions from the same ovarian cancer patients. Furthermore, cancer spheres (representing potential MICs) displayed significantly lower levels of TFPI-2 than corresponding cell line and some primary cultured cancer cells. The cancer spheres showed a modest increase in methylation percentage in three specific CpG sites within the TFPI-2 promoter. Our results suggest that TFPI-2 loss plays a role in the cancer cell escape from the primary tumor. Future studies will determine the mechanism and the biological consequences of the progressive loss of TFPI-2 in cancer. Funding: FONDECYT 11140657, 1160800, 1140970, 3140335, 3150028, CORFO L2 13IDL2-18608, IMII-P09/016-F, CONICYT-FONDAP 15130011, BMRC 13CTI21526-P6 Citation Format: Jacqueline Fry, Sumie Kato, Lorena Abarzua, Pamela Gonzalez, Carolina Ramirez, Elisa Cumsille, Erasmo Bravo, Raimundo Correa, Juan E. Leiva, Cesar Paredes, Juan C. Roa, Carolina Ibañez, Mauricio Cuello, Gareth I. Owen, Maria L. Bravo. Regulation of TFPI-2 in the progression of ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5516. doi:10.1158/1538-7445.AM2017-5516
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