miR-181a、miR-181b在人胃癌细胞和组织中的表达

miRNA-19b regulates proliferation of human colon cancer cell line HT-29

AIM: To investigate whether miR-19b influences the proliferation of human colon cancer cell line HT-29 and the possible mechanisms.

METHODS: Potential targets of miR-19b were predicted using computer-aided algorithms TargetScan, PicTar and microRNA.org. We transfected HT-29 cells with synthetic miR-19b mimic or miR-19b inhibitor using Lipofectamine 2000 to up-regulate or down-regulate miR-19b. Protein levels of suppressor of cytokine signaling 3 (SOCS3), cyclinD1, signal transducer and activator of transcription 3 (STAT3) and phosphorylated-STAT3 (p-STAT3) were determined by Western blot. CCK8 and flow cytometry were conducted for the detection of proliferation ability and cell cycle of the treated cells.

RESULTS: Compared to control cells, overexpression of miR-19b in HT-29 cells down-regulated the protein level of SOCS3 (P < 0.01), but not that of SOCS3 mRNA. Furthermore, down-regulation of SOCS3 by miR-19b caused phosphorylation of STAT3 (P < 0.01) as well as induced expression of cyclinD1 (P < 0.01), which could promote cell proliferation (P < 0.01) by transition from G₁ phase to S and G₂ phase (P < 0.05 or P < 0.01). On the contrary, down-regulation of miR-19b in HT-29 cells could restrain cell proliferation (P < 0.01), restore cell arrest (P < 0.05 or P < 0.01), activate STAT3 (P < 0.01) and induce expression of cyclinD1 (P < 0.01) due to up-regulated expression of SOCS3 (P < 0.01).

CONCLUSION: Expression of miR-19b not only regulates the proliferation but also influences the cell cycle of HT-29 cells, possibly by inhibiting the expression of SOCS3.