[Effect of silencing hypoxia-inducible factor-1 alpha by RNA interference on human breast carcinoma cell line].

OBJECTIVE: To investigate the effect of short hairpin RNA (shRNA) targeting hypoxia-inducible factor-1 alpha (HIF-1 alpha) on the human breast carcinoma MCF-7 cell line.

METHODS: The hypoxia environment was achieved by treating cells with cobalt chloride. The shRNA eukaryotic expression vector targeting HIF-1 alpha was constructed, and transfected into MCF-7 cells through lipofectamine 2000. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to study the expression of vascular endothelial growth factor (VEGF). The mRNA and protein level of HIF-1 alpha were detected by real-time PCR and Western blot. Sub-G1 apoptotic population analysis, Annexin V/PI binding assay, and DNA ladder analysis were applied to investigate the cell apoptosis. The cell cycle was detected by flow cytometry.

RESULTS: The mRNA and protein level of HIF-1 alpha increased after exposure of MCF-7 cells to hypoxia (P < 0.01). However, apoptosis was lower in hypoxia compared with normoxia (P < 0.05). The HIF-1 level of MCF-7 transfected with HIF-1 alpha shRNA decreased approximately 91.63% (P < 0.01). When the cells were treated with or without apoptosis inducer Ara-C, the apoptosis of MCF-7 cells transfected with HIF-1 alpha shRNA increased by 1.75 times (P < 0.01) and 61. 31 times (P < 0.01), respectively. The expression of VEGF in MCF-7 cells transfected with HIF-1 alpha shRNA decreased 66.8% compared with untransfected cells (P < 0.05). Cell cycle progression was inhibited when the MCF-7 cells were transfected with HIF-1 alpha shRNA.

CONCLUSIONS: HIF-1 alpha plays an anti-apoptotic role in human breast carcinoma MCF-7 cell line. The shRNA we designed targeting HIF-1 alpha in MCF-7 can promote cell apoptosis, inhibit the expression of VEGF, and delay cell cycle progression.