MicroRNA-214 suppresses cell proliferation and migration and cell metabolism by targeting PDK2 and PHF6 in hepatocellular carcinoma

Abstract

MiR-214 has been reported to act as a tumor suppressor or oncogene involved in various malignancies. However, the biological functions and molecular mechanisms of miR-214 in hepatocellular carcinoma (HCC) still remain unclear. Previous studies suggest that pyruvate dehydrogenase kinase 2 (PDK2) and plant homeodomain finger protein 6 (PHF6) may be involved in some tumor cell proliferation and migration. Therefore, we studied the relationship between PDK2/PHF6 and miR-214. The expression of miR-214, PDK2, and PHF6 was determined by quantitative real-time polymerase chain reaction in HCC tissues and cell lines. The Luciferase reporter assay was used to confirm the interaction between miR-214 and PDK2/PHF6. Cell proliferation, apoptosis, and migration were evaluated by cell counting kit-8 assay, flow cytometry, and transwell assay, respectively. The expressions levels of α-smooth muscle actin (α-SMA) and E-cadherin were detected via immunofluorescence assay. Here, we found that the expression of miR-214 decreased in HCC and was negatively correlated with PDK2 and PHF6. Moreover, PDK2 and PHF6 were the direct targets of miR-214 in HCC cells. Functional analysis showed that knockdown of PDK2 or PHF6 as well as miR-214 overexpression significantly suppressed cell proliferation and migration in HCC cells. Furthermore, we found that the suppression of cell proliferation and migration through PDK2 or PHF6 knockdown could be partially reversed by miR-214 down-regulation. Moreover, we demonstrated a decrease of mesenchymal cell marker α-SMA and increase of the epithelial marker E-cadherin after miR-214 overexpression, PDK2 knockdown or PHF6 knockdown, respectively, which also suggested that cell proliferation and migration were suppressed. Additionally, lactate and pyruvic acid production experiments confirmed miR-214 could suppress the HCC cell lactate and pyruvic acid levels by down-regulating PDK2/PHF6. In conclusion, MiR-214 may act as a tumor suppressor gene, presenting its suppressive role in cell proliferation and migration of HCC cells by targeting PDK2 and PHF6, and might provide a potential therapy target for patients with HCC.