Abstract 5086: To identify the critical factors in extracellular vesicles derived from cancer-associated fibroblasts for drug resistance of gastric cancer cells
Authors: Uchihara Tomoyuki , Miyake Keisuke , Oda Eri , Koga Yuki , Yagi Taisuke , Kuroda Daisuke , Eto Tsugio , Kiyozumi Yuki , Arima Kota , Sawayama Hiroshi , Hiyoshi Yukiharu , Iwatsuki Masaaki , Baba Yoshifumi , Miyamoto Yuji , Yoshida Naoya , Baba Hideo , Ishimoto Takatsugu 
Published: August 2018

Abstract
Background: Tumor microenvironment consists of various types of cells. Although cancer associated fibroblasts (CAFs) have been reported to enhance tumor progression and anticancer drug resistance through secretion of soluble factors so far, the crucial mechanism is not fully understood. On the other hand, advanced gastric cancer (GC) is still poor prognosis due to metastasis and recurrence despite the progression of diagnosis and treatment. The aim of this study is to identify the molecular mechanism underlying anticancer drug resistance mediated by CAFs in GC.
Methods: We have isolated CAFs from surgically resected GC tissues and collected conditioned medium (CM) of CAFs. Human GC cell lines with or without CAF-CM were examined the drug sensitivity and analyzed expression of specific genes using quantitative reverse transcription PCR. We isolated extracellular vesicles (EVs) from CAF-CM by ExoQuick-TC ® and ultracentrifugal separation. We observed GC cells with confocal microscopy after the solution of stained EVs treated. We performed EVs from CAF-CM and GC-CM to mass analysis.
Results: GC cells with CAF-CM showed drug resistance on normal coated plates. Moreover, we found that GC cells with CAF-CM on extracellular matrix (ECM)-coated plates showed remarkable morphological change and much higher drug resistance than those without CAF-CM. In contrast, GC cells with GC cell line-CM on ECM- coated plates did not show morphological change. We also found that EVs isolated from CAF-CM caused morphological change and drug resistance of GC cells. Moreover, we identified five proteins included in CAF-EVs as possible candidates involving in GC drug resistance by mass analysis. Gene expression analysis revealed that SNAI2, which is one of the Epithelial Mesenchymal Transition (EMT)-related gene, was significantly up-regulated in GC cells cultured with CAF-CM or EVs from CAF-CM on ECM-coated plates.
Conclusion and future perspective: These findings in current study suggest that EVs from CAFs cause characteristic gene expression change and enhance drug resistance along with morphological change of GC cells. We are trying to identify the critical factor in CAF-EVs for drug resistance of GC cells.
Citation Format: Tomoyuki Uchihara, Keisuke Miyake, Eri Oda, Yuki Koga, Taisuke Yagi, Daisuke Kuroda, Tsugio Eto, Yuki Kiyozumi, Kota Arima, Hiroshi Sawayama, Yukiharu Hiyoshi, Masaaki Iwatsuki, Yoshifumi Baba, Yuji Miyamoto, Naoya Yoshida, Hideo Baba, Takatsugu Ishimoto. To identify the critical factors in extracellular vesicles derived from cancer-associated fibroblasts for drug resistance of gastric cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5086.