Upregulation of SNX5 Predicts Poor Prognosis and Promotes Hepatocellular Carcinoma Progression by Modulating the EGFR-ERK1/2 Signaling Pathway

Endocytosis is an essential component of cell motility, which facilitates the malignant behavior of cancer. Sorting nexin (SNX) family members are associated with tumor progression. However, the role and mechanism of SNX5 in hepatocellular carcinoma (HCC) progression remain largely unknown. In this study, we investigated the clinical significance and possible involvement of SNX5 in the progression of HCC. Here, we showed that SNX5 was upregulated in tumors compared with adjacent nontumorous tissues in HCC patients. The upregulation of SNX5 in HCC was associated with vascular invasion, intrahepatic metastasis, and poor prognosis. The overexpression of SNX5 promoted HCC cell proliferation, migration, invasion, and metastasis, whereas silencing SNX5 expression resulted in decreased cell proliferation, migration, and invasion. Knockdown of SNX5 significantly inhibited HCC cell proliferation by inducing G1/S transition arrest. Mechanistically, we demonstrated that SNX5 promoted cell proliferation, migration, and invasion via the activation of the EGFR-ERK1/2 pathway by blocking EGF-mediated EGFR internalization. We found that SNX5 interacted with EGFR in HCC cells. Moreover, SNX5-induced cell proliferation, migration, and invasion were partially reversed by the knockdown of EGFR or by ERK1/2 inhibitors. In addition, we demonstrated that SNX5 knockdown sensitized HCC cells to tyrosine kinase inhibitors, including erlotinib and sorafenib. Taken together, our results indicate that SNX5 promotes HCC cell proliferation and metastasis via inhibiting the endocytosis and degradation of EGFR, thereby activating the ERK1/2 signaling pathway. Our work also suggests that SNX5 is a potential therapeutic target for HCC.