Clinical Significance of Combined Epithelial-Mesenchymal Transition Markers Expression and Role of Rac1 in Hepatocellular Carcinoma

Epithelial-mesenchymal transition (EMT) has been implicated in cancer progression, invasion, and metastasis. We aimed to evaluate the correlations between clinicopathological characteristics and EMT markers in patients with hepatocellular carcinoma (HCC) who underwent surgical resection and to identify the key regulator in EMT process. Fresh-frozen HCC tissues and adjacent nontumor liver tissues from 30 patients who underwent surgical resection were provided by the Gachon University Gil Medical Center Bio Bank. Human HCC cell lines, Hep3B, SNU449, and Huh7 cells were transfected with Rac1 siRNA and exposed to hypoxic conditions. The combined EMT markers expression (down-expression of E-cadherin and overexpression of p21-activated kinases 1 (PAK1)/Snail) by Western blot in HCC tissues when compared to adjacent nontumor liver tissues was significantly associated with macrovascular invasion (p = 0.021), microvascular invasion (p = 0.001), large tumor size (p = 0.021), and advanced tumor stage (p = 0.015). Patients with combined EMT markers expression showed early recurrence and poor overall survival. In vitro studies showed that Rac1 knockdown decreased the expression of EMT markers including PAK1 and Snail in hypoxia-induced Hep3B cells and suppressed the migration and invasion of hypoxia-induced HCC cells. Rac1 may be a potential therapeutic target for inhibition of EMT process through the inhibition of PAK1 and Snail in HCC.

Automated summary

This study evaluated the correlations between clinicopathological characteristics and epithelial-mesenchymal transition (EMT) markers in hepatocellular carcinoma (HCC) patients who underwent surgical resection, and identified a key regulator in the EMT process. The down-expression of E-cadherin and overexpression of p21-activated kinases 1 (PAK1)/Snail in HCC tissues were significantly associated with macrovascular invasion, microvascular invasion, large tumor size, and advanced tumor stage. Patients with these EMT markers showed early recurrence and poor overall survival. In vitro studies showed that inhibition of Rac1 decreased the expression of EMT markers and suppressed the migration and invasion of HCC cells. Therefore, Rac1 may be a potential therapeutic target for inhibiting EMT process in HCC.