Diallyl disulfide inhibits TGF­ß1­induced upregulation of Rac1 and ß­catenin in epithelial­mesenchymal transition and tumor growth of gastric cancer.

Transforming growth factor­ß1 (TGF­ß1) has been demonstrated to promote epithelial­mesenchymal transition (EMT), invasion and proliferation in tumors via the activation of Rac1 and ß­catenin signaling pathways. The present study investigated the effects of diallyl disulfide (DADS) on TGF­ß1­induced EMT, invasion and growth of gastric cancer cells. TGF­ß1 treatment augmented EMT and invasion, concomitantly with increased expression of TGF­ß1, Rac1 and ß­catenin in gastric cancer cells. DADS downregulated the expression levels of TGF­ß1, Rac1 and ß­catenin. DADS, TGF­ß1 receptor inhibitor as well as Rac1 inhibitor antagonized the upregulation of the TGF­ß1­induced expression of these genes, abolishing the enhanced effects of TGF­ß1 on EMT and invasion. Blocking the TGF­ß1 receptor through inhibition resulted in the decreased expression of Rac1 and ß­catenin. Rac1 inhibitor reduced the TGF­ß1­induced ß­catenin expression. In addition, DADS and the aforementioned inhibitors attenuated the TGF­ß1­induced tumor growth and the expression changes of E­cadherin, vimentin, Ki­67 and CD34 in nude mice. These data indicated that the blockage of TGF­ß1/Rac1 signaling by DADS may be responsible for the suppression of EMT, invasion and tumor growth in gastric cancer.