Driver genes conducing to peritoneal metastasis in advanced gastric cancer remain to be clarified. S100A4 is suggested to evolve in metastasis of gastrointestinal cancer, we aim to explore the role of S100A4 plays in metastasis of advanced gastric cancer and the potential mechanism. Transfection of siRNA or cDNA was applied to alter the expression of protein S100A4 and MYH9, investigation of the expression of epithelial and mesenchymal transition (EMT) associated markers was followed. Cell migration assay was used to screen the alteration of migration ability regulated by S100A4 and MYH9. IHC analysis for tissue sample microarray was performed to reveal their relationship with clinical pathological parameters and potential capacity of predicting survival. Consistent overexpression of S100A4 and MYH9 were found in peritoneal metastasis and primary site compared with adjacent normal tissue. Low expression of S100A4 led to increased epithelial markers as wells as decline of mesenchymal makers, while overexpression of S100A4 led to inverse impact. S100A4 expression was closely correlated with increased migration ability and EMT process induced by TGF-β stimulation. Interference of S100A4 led to downregulation of MYH9 and inactivation of Smad pathway through participating in EMT process, which could be reversed by overexpression of MYH9. Moreover, co-expression of S100A4 and MYH9 was identified in tissue microarray and confirmed by immunofluorescence assay. In conclusion, overexpression of S100A4 and downstream molecular MYH9 in advanced gastric cancer predicted poor prognosis; oncogene S100A4 facilitate EMT process induced by TGF-β stimulation, suggesting a potential target in management of peritoneal metastasis of gastric cancer.
Keywords: EMT; MYH9; S100A4; gastric cancer; peritoneal metastasis.