miR-145 Inhibits Th9 Cell Differentiation by Suppressing Activation of the PI3K/Akt/mTOR/p70S6K/HIF-1α Pathway in Malignant Ascites from Liver Cancer.

Purpose: Our previous experiments confirmed that T helper type 9 (Th9) cells were involved in the occurrence and development of malignant ascites caused by liver cancer. The current study investigated the mechanism underlying microRNA (miR-145)-mediated inhibition of Th9 cells in an malignant ascites model with liver cancer. Materials and Methods: CD4+ T cells were induced to differentiate Th9 cells after transfection with miR-145 mimics or negative control. A malignant ascites mouse model was transfected with miR-145agomir or negative control. Th9 cells were detected by flow cytometry. Enzyme-linked immunosorbent assay was applied to detect the interleukin 9 (IL-9) cytokine and hypoxia-inducible factor 1 alpha (HIF-1 alpha). RT-PCR was used to detect the expression of miR-145 and phosphatidylinositol-3-kinase/Akt/mammalian target of rapamy-cin/p70 ribosomal protein S6 kinase/HIF-1 alpha (PI3K/Akt/mTOR/p70S6K/HIF-1 alpha) mRNA. Western blotting and immunofluorescence were performed to detect the expression of PI3K/Akt/mTOR/p70S6K/HIF-1 alpha-related proteins. Results: In vitro experiments showed that miR-145 inhibited Th9 cell polarization, HIF-1 alpha expression, and PI3K/Akt/mTOR/p70S6K pathway activation. In the malignant ascites mouse model, miR-145 also demonstrated inhibitory effects on Th9 cell differentiation through the PI3K/Akt/mTOR/p70S6K/HIF-1 alpha pathway. Conclusion: miR-145 may inhibit Th9 cell differentiation through the PI3K/Akt/mTOR/p70S6K/HIF-1 alpha pathway. These findings suggest a novel therapeutic target for malignant ascites from liver cancer.