Background: The ERBB2 oncogene hypothesis is challenged in hepatocellular carcinoma (HCC) with the conflicting evidences of human epidermal growth factor receptor 2 (HER2) overexpression. HER2 could be a new target as a treatment option for HCC as well as tumor recurrence after surgery. HER2 in HCC biology needs further explorations.
Methods: Clinical and mRNA data of HCC patients were obtained from TCGA HCC cohort, GSE89377 and GSE115018. Western Blotting and immunohistochemistry were employed to test expression of HER2, E-cadherin, and Vimentin. In HepG2, JM1, HER2-transfected McA cells, and TGF-β cocultured JM1 cells, HCC biology, including cell survival, proliferation, and epithelial-to-mesenchymal transition (EMT) phenotypes were evaluated.
Results: ERBB2 mRNA amplification was found in HCC datasets, and its expression was downregulated in high grade HCC with a worse overall survival. HER2 overexpression was identified in H4IIE, HepG2, JM1 cells, and 82% (14/17) HCC samples, and tumor stage was correlated with expression of HER2, E-cadherin, and Vimentin (P < 0.05). Trastuzumab with the high concentrations suppressed proliferation of HER2-positive hepatoma cells (P < 0.05); in the coculture model to induce EMT of JM1 cells, HER2 expression increased with downregulated E-cadherin and upregulated Vimentin. Trastuzumab intravenous injection inhibited in vivo tumor size and metastases (P < 0.05). Signal analysis revealed that HER2 functioned through upregulation of β-catenin and inhibition of SMAD3.
Conclusion: HER2 expression pattern is linked with tumor stage and overall survival; the transforming function of HER2 is found more relevant through β-catenin and SMAD3. HER2-targeted treatment is recommended to suppress the HER2-mediated tumor growth during postoperative liver regeneration.
Keywords: Trastuzumab; epithelial-to-mesenchymal transition; hepatocellular carcinoma; human epidermal growth factor receptor 2; tumor recurrence.
© 2019 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.