High STRN Expression Promotes HCC Invasion and Migration but Not Cell Proliferation or Apoptosis through Facilitating Epithelial-Mesenchymal Transition.

A STRN-ALK fusion protein has been recently identified as a potential therapeutic target in multiple cancers; however, the role of STRN alone in regulating the biological function of hepatocellular carcinoma (HCC) remains unclear. In this study, we firstly detected an overexpression of STRN in HCC tissues compared to that in adjacent nontumour (ANT) tissues through IHC analysis, and the expression level of this protein was positively correlated with lymph node metastasis and TNM stage. In vitro, high expression of STRN was also confirmed in different HCC cell lines, and regulation of STRN expression in Huh7 cells did not significantly affect tumour cell proliferation or apoptosis but was positively correlated with tumour cell invasion and migration capacities. Moreover, both the knockdown and overexpression of STRN in Huh7 cells can lead to cell morphological changes that are accompanied with an alteration of epithelial-mesenchymal transition (EMT) molecular markers E-cadherin and Vimentin. Finally, STRN was further proved to be negatively related to E-cadherin expression but positively related to Vimentin expression in human HCC tissue samples. Taken together, STRN is upregulated in HCC and acts as a tumour promoter regulating cell invasion and migration through facilitating the EMT process.

Connexin 32 downregulation is critical for chemoresistance in oxaliplatin-resistant HCC cells associated with EMT.

Background: Oxaliplatin (OXA)-based chemotherapy is critical in the management of advanced hepatocellular carcinoma (HCC); however, acquired drug resistance has largely restricted its clinical efficacy. This study aims to explore the key mechanisms and regulatory factors determining chemosensitivity in HCC. Methods: We developed OXA-resistant (OR) HCC cells and used multiple methods, including real-time RT-PCR, Western blot, immunofluorescence, transwell invasion assay, wound-healing assay, MTT assay, gene transfection, and immunohistochemistry to achieve our goals. Results: We found that OR HCC cells showed a typical epithelial-mesenchymal transition (EMT) phenotype. Meanwhile, the expression of Cx32, a major member of the liver connexin (Cx) family, was lowly expressed in OR HCC cells. Downregulation of Cx32 in parental HCC cells led to EMT induction and thereby reduced OXA cytotoxicity, while Cx32 upregulation in OR HCC cells could reverse the EMT phenotype and partially restore chemosensitivity to OXA. Finally, in human HCC tissue samples, Cx32 was positively correlated with the expression of the EMT marker E-cadherin and negatively correlated with the expression of Vimentin. Conclusion: Our findings demonstrated that downregulation of Cx32 may be an important determinant for HCC cells to acquire EMT-related acquired drug resistance to OXA, and targeting Cx32 could be a novel strategy to overcome OXA resistance in HCC.