RESUMO
<p><b>OBJECTIVE</b>To investigate the effect of decreased expression of high mobility group Box-1 on the proliferation and apoptosis of HepG2 cells.</p><p><b>METHODS</b>Three specific siRNAs of HMGB1 were designed and synthesized, and were transiently transfected into HepG2 cells by Lipofectamine 2000. The HMGB1 expression in HepG2 cells was detected by RT-PCR and Western blotting respectively. The proliferation activity in vitro was assessed by MTT assay. In situ apoptosis was evaluated by terminal deoxynucleotidyl transferase-deoxyuridine triphosphate nick end labeling (TUNEL) assay.</p><p><b>RESULTS</b>All of these specific HMGB1-siRNAs (1, 2, 3) efficiently and specifically inhibited the expression of the HMGB1 gene, and the levels of HMGB1 mRNA were 1.147+/-0.024, 1.014+/-0.042, 0.435+/-0.055, respectively, in HMGB1-siRNAs transfection group, which were significantly lower than that in Lipofectamine 2000 alone group (1.411+/-0.065, P < 0.01). Correspondingly, all of these specific HMGB1-siRNAs (1, 2, 3) could efficiently and specifically inhibit the expression of the HMGB1 protein, and the levels of HMGB1 protein were 0.369+/-0.035, 0.340+/-0.028, 0.097+/-0.020, respectively, in HMGB1-siRNAs transfection group, which were significantly lower than that in Lipofectamine 2000 alone group (0.553+/-0.051, P < 0.01). Of the 3 specific HMGB1-siRNAs, HMGB1-siRNA-3 (siRNAH3) had the highest inhibition rate (80%). The proliferation of HepG2 cells was markedly inhibited by siRNAH3 transfection. Compared to mock-transfection, siRNAH3 transfection dramatically suppressed the proliferation of HepG2 cells (P < 0.01). Moreover, siRNAH3 can induce apoptosis (P < 0.01).</p><p><b>CONCLUSION</b>siRNA targeting HMGB1 mRNA can specifically reduce HMGB1 gene and protein expression. siRNAH3 can effectively suppress the proliferation and induce apoptosis of HepG2 cells.</p>