Abstract: Objective　To study the effects and its mechanisms of arsenic trioxide (As2O3) on cell growth and human telomer- ase reverse transcriptase (hTERT) of human tongue cancer cells (Tca8113 cell line).Methods　The growth inhibition rates of Tca8113 by various concentrations of As2O3were detected byMTTmethod. Cell apoptosis was detected by FCM labeled with An- nexin V-FITC. hTERT gene expression was detected by RT-PCR method. hTERT protein of Tca8113 cells was determined by Western blot assay.Results　The results showed that As2O3could inhibit the growth of Tca8113 effectively and apoptotic rate of Tca8113 cells was obviously increased in a dose and time-dependent manner. (83·40±7·31)% cells treated with 5μmol/L As2O3were inhibited on 72 hour point, the early apoptosis rate reached on 26·40%±3·42% at that time. Moreover hTERTmR- NA and proteinwere decreased depended on the dose and time of As2O3, mRNA expressions of hTERT in test groupswere greatly lower than that of control group on 72 hour point.Conclusion　It was suggested that As2O3could significantly inhibit the growth of Tca8113 cells by inducing causing cell apoptosis and down-regulating the expression of hTERT mRNA gene and protein which might be one of its action mechanisms.

Key words: arsenic trioxide, human tongue cancer cell lines, cell apoptosis, human telomerase reverse transcriptase