Transforming growth factor-β1 induces connective tissue growth factor expression and promotes peritoneal metastasis of gastric cancer.

Transforming growth factor-β1 (TGF-β1) is involved in human cancer development and progression. Nonetheless, the role of TGF-β1 as regards peritoneal metastasis of gastric cancer has not been completely characterized. In the present study, we investigated the exact role of TGF-β1 on peritoneal metastasis of gastric cancer. The results indicated that human peritoneal mesothelial cells (HPMCs) exposed to TGF-β1 or serum-free conditional medium (SF-CM) of SGC7901 that produced a large amount of TGF-β1 became exfoliated, apoptosis and exhibited signs of injury, and the tumor-mesothelial cell adhesion significantly increased. Connective tissue growth factor (CTGF) expression was also increased when HPMCs were exposed to TGF-β1 or SF-CM of SGC7901. However, these effects were significantly decreased when HPMCs were exposed to SF-CM of SGC7901-TGFβS, a TGF-β1 knockdown stable cell line. Animal studies revealed that nude mice injected with SGC7901-TGFβS cells featured a smaller number of peritoneal seeding nodules and lower expression of CTGF in ascites than the control cell lines. These findings suggest that TGF-β1 promotes peritoneal metastasis of gastric cancer and induces CTGF expression. Therefore, blockage of TGF-β1 or TGF-β1 signaling pathway might prevent and treat peritoneal metastasis of gastric cancer.