Decreased expression of microRNA-223 promotes cell proliferation in hepatocellular carcinoma cells via the insulin-like growth factor-1 signaling pathway

Hepatocellular carcinoma (HCC) is one of the most harmful types of cancer. Previous studies have demonstrated that microRNA (miR)-223 is downregulated in the serum and tumor tissue of patients with HCC. The present study aimed to investigate the regulatory role of miR-223 on insulin-like growth factor-1 receptor (IGF-1R) and downstream factors in HCC. The Hep3B cell line was transfected with miR-223 mimic and inhibitor. Following transfection, cell proliferation was analyzed using a cell counting kit 8 assay and cellular apoptosis was assessed using flow cytometry. The expression of key molecules in the IGF-1 signaling pathway, including IGF-1R, protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) were determined using reverse transcription-quantitative polymerase chain reaction and western blot analysis. The results demonstrated that the mRNA and protein levels of IGF-1R were decreased in cells transfected with miR-223. Transfection with miR-223 also decreased cell proliferation and promoted cell apoptosis. Expression of total Akt and ERK, and their active forms phosphorylated Akt and ERK, were also downregulated following transfection with miR-223. By contrast, transfection with miR-223 inhibitor did not induce any effects on Hep3B cell proliferation and apoptosis, and did not affect the expression of key molecules in the IGF-1 pathway. Therefore, the results of the present study indicate that miR-223 decreases the proliferation and promotes the apoptosis of HCC cells. Its molecular mechanism of action may at least partially occur via the direct regulation of IGF-1R and indirect reduction of the downstream molecules Akt and ERK.