Abstract TMEM-042: MALIGNANT EXTRACELLULAR VESICLES CAUSE MESOTHELIAL CELL DAMAGE TOWARD PERITONEAL DISSEMINATION IN OVARIAN CANCER

Abstract

Abstract PURPOSE: To elucidate novel mechanisms of peritoneal dissemination by focusing on extracellular vesicles BACKGROUNDS AND SUMMARY: Metastasis to the abdominal cavity is frequently observed in ovarian cancer patients and is one of the reasons for the unfavorable outcomes. Extracellular vesicles (EVs), including exosomes and microvesicles, are small membrane vesicles that contain various bioactive molecules, such as microRNAs, mRNAs and proteins, and they are released from all cell types and play key physiological roles in intercellular communication. Recent evidence has demonstrated that cancer cells secrete EVs to both proximal surrounding cells and distal sites, thereby enabling the development of a cancer microenvironment that in turn promotes cancer metastasis. We established orthotopic mouse models by using 4 ovarian carcinoma cell lines with different metastatic traits and investigated the functions of cancer-derived EVs. The EVs from highly metastatic cells strongly induced metastatic behavior in moderately metastatic tumors. Notably, the metastatic cancer EVs efficiently induced apoptotic cell death in mesothelial cells in vitro and in vivo, thus resulting in the destruction of the peritoneal mesothelium barrier. Whole transcriptome analysis showed that MMP1 was significantly elevated in mesothelial cells treated with highly metastatic cancer EVs, and intact MMP1 mRNAs were selectively packaged in the EVs. Importantly, MMP1 expression in ovarian cancer is tightly correlated with a poor prognosis, particularly in stage I patients. Moreover, we found MMP1 mRNA-carrying EVs in the ascites of cancer patients, and these EVs also induced apoptosis in mesothelial cells. CONCLUSIONS: Our findings provide a promise for the understanding of a previously unknown mechanism for peritoneal dissemination that is associated with cancer-derived EVs, and which may be novel biomarkers for prognosis and can provide a new therapeutic strategy for inhibiting metastasis by disrupting the EVs. Citation Format: Akira Yokoi and Takahiro Ochiya. MALIGNANT EXTRACELLULAR VESICLES CAUSE MESOTHELIAL CELL DAMAGE TOWARD PERITONEAL DISSEMINATION IN OVARIAN CANCER [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr TMEM-042.