miR-409 down-regulates Jak-Stat pathway to inhibit progression of liver cancer

To elucidate the influence of microRNA-409 and the Jak-Stat pathway on the development of liver cancer.

The quantitative Real-time polymerase chain reaction (qRT-PCR) method was used to detect the expression of microRNA-409 in hepatocarcinoma, paracancerous tissues and normal liver tissues, and the correlation between its expression and clinicopathological parameters of patients was analyzed, with the area under the microRNA-409 curve (AUC) being detected. The level of microRNA-409 in different liver cancer cells was detected by qPCR. Then it was overexpressed or knock-downed in the liver cancer cells by cell transfection technique. The cell apoptosis and viability after inhibition or overexpression of microRNA-409 were evaluated by propidium iodide (PI) staining and cell counting kit-8 (CCK-8) assay. Subsequently, Jak2 and Stat3 mRNA levels were detected by qPCR in hepatocarcinoma and paracancerous tissues, with their protein levels analyzed by Western blot after microRNA-409 was inhibited or up-regulated. At last, CCK-8 assay was performed to evaluate the effect of Jak2 on cell viability.

Compared with paracancerous and normal liver tissues, the level of microRNA-409 was remarkably reduced in hepatocarcinoma tissues and was negatively correlated with tumor stage, tumor size and overall survival time of patients with liver cancer. Meanwhile, microRNA-409 expression in hepatoma cell lines was also strikingly lower than that in normal liver cells. After overexpression of microRNA-409 in HHCC, cell viability significantly decreased while apoptosis increased, and opposite results were shown in HepG2 cells after miR409 was knock-downed. In liver cancer tissues, the levels of Jak2 and Stat3 were significantly higher than those in adjacent tissues. Additionally, up-regulating microRNA-409 reduced the level of Jak2 and Stat3 protein, while down-regulating it elevated them. In addition, Jak2 could reverse the inhibitory effect of microRNA-409 on the proliferation of hepatoma cells.

Highly-expressed microRNA-409 can down-regulate the Jak-Stat signaling pathway and inhibit cell proliferation to slow down the progression of liver cancer.