Rab27b, a Regulator of Exosome Secretion, Is Associated With Peritoneal Metastases in Gastric Cancer

Sho Nambara, Takaaki Masuda, Kosuke Hirose, Qingjiang Hu, Taro Tobo, Yuki Ozato, Junji Kurashige, Yoshiki Hiraki, Yuichi Hisamatsu, Tomohiro Iguchi, Keishi Sugimachi, Eiji Oki, Tomoharu Yoshizumi, Koshi Mimori

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND/AIM: Peritoneal metastasis (PM) of gastric cancer (GC) leads to poor clinical outcomes. Tumor-derived exosomes promote metastasis via communication between tumor cells and host cells. In this study, we investigated the effect of Rab27, which is required for exosome secretion, on the PM of GC. MATERIALS AND METHODS: We established a stable knockdown of two Rab27 homologs, Rab27a and Rab27b, in human GC cells (58As9) with a high potential of PM. We examined the level of exosome secretion from Rab27-knockdown 58As9 cells by Western blotting and the ability of Rab27b knockdown to suppress PM in 58As9 cells using a mouse xenograft model. In vitro proliferation and invasion assays were performed in the Rab27b-knockdown cells. Next, Rab27b expression was evaluated in human GC tissues by immunohistochemistry. Finally, we assessed the clinicopathological and prognostic significance of Rab27b expression by RT-qPCR in both our and other TCGA datasets of GC. RESULTS: Rab27a and Rab27b knockdown in 58As9 cells decreased the secretion of exosomes, characterized by the endocytic marker CD63. Rab27b knockdown decreased PM in vivo without affecting the in vitro proliferation or invasion ability of 58As9 cells. In human GC tissues, Rab27b was overexpressed in tumor cells. The overall and recurrence-free survival rates were significantly lower in GC patients with high compared to low Rab27b mRNA expression in our and other TCGA datasets. CONCLUSION: Rab27b expression potentially serves as a poor prognostic biomarker, possibly affecting PM via exosome secretion from GC cells.

Original languageEnglish
Pages (from-to)30-39
Number of pages10
JournalCancer Genomics and Proteomics
Volume20
Issue number1
DOIs
Publication statusPublished - Jan 1 2023

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cancer Research

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