MiR-21 regulates proliferation and apoptosis of oral cancer cells through TNF-α.

OBJECTIVE: MicroRNA (miRNA) can widely regulate gene expression. More importantly, various miRNA molecules have been found with regulatory functions for tumor cell proliferation or apoptosis. The study showed that miR-21 inhibited apoptosis of cultured cancer cells, whilst tumor necrosis factor α (TNF-α) plays important roles in the proliferation of tumor cells. This study manipulated miR-21 expression in cultured oral cancer cells and aimed to investigate its effects on TNF-α expression, and on proliferation or apoptosis of cancer cells.

MATERIALS AND METHODS: Specific agonist and antagonist were synthesized based on miR-21 sequence. In vitro cultured oral cancer cell line, SCC-15 was transfected with agonist or antagonist, in parallel with normal cultured cells as negative control group. Quantitative Real-time PCR (qRT-PCR) was used to measure mRNA expression of miR-21 and TNF-α in transfected cells. Western blot was used for measuring TNF-α expression, and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) or Hoechst-33342 staining was used to measure proliferation and apoptosis of SCC-15 cells.

RESULTS: MiR-21 expression was potentiated or depressed with transfection of agonist or antagonist, respectively, illustrating the effectiveness of synthesized sequence in cultured SCC-15 cells. Moreover, TNF-α expression was positively correlated with miR-21, TNF-α up-regulation significantly potentiated the proliferation potency of SCC-15 cells, and TNF-α down-regulation remarkably weakened proliferation potency (p<0.05). The TNF-α expression did not affect apoptosis of SCC-15 cells (p>0.05 compared to the control group).

CONCLUSIONS: MiR-21 could participate in the proliferation of cultured SCC-15 cells via targeting TNF-α expression, but without any significant effects on cell apoptosis.