Abstract: OBJECTIVE: To study the effect of high-dose long-term benzo (a)pyrene [B(a)P] exposure on miRNAs expression profile in lung tissues of mice and analyze the potential mechanism of miRNAs on the B (a)P-induced health damage. METHODS：40 ICR mice were divided into control group and exposure groups randomly. Each group included 10 male and 10 female mice. Exposure group mice were treated with 50 mg/kg B(a)P (twice a week) for 8 weeks by intragastric administration. Control mice were treated with same volume of olive oil solvent. Then，all mice were fed for another 8 weeks without exposure. The total RNA was isolated from mice lung tissues. The miRNAs expression profiles were evaluated by SOliD high-throughput sequencing technique and the difference expression of miRNAs were analyzed. Real time-PCR was used to confirm the miRNAs expression. The potential targets of miRNAs were calculated by TargetScan，miRanda and picTar software. RESULTS：Most of miRNAs were found at low expression levels in lung tissue. Compared with control mice，109 miRNAs expression changed significantly in lung tissue of B (a)P exposure mice. Of these 109 miRNAs，50 were up-regulated and 59 were down-regulated，the expression changes were 7.43-fold and 40.63-fold，respectively. miR-20b was analyzed by real time-PCR to verify the sequencing. The result of real time-PCR was consistent with sequencing. The potential targeted proteins of miR-20b were involved in cell proliferation，cell cycle，apoptosis and oncogenesis. CONCLUSION：High-dose long-term B(a)P exposure could specifically alter miRNAs expression profiles. The differential expression of miRNAs may play an important role for the B(a)P-induced health damage.

Key words: microRNAs, sequencing, expression profile, benzo (a)pyrene