[Effect of homoharringtonine on expression of human telomerase reverse transcriptase mRNA in HL-60 cells].

To investigate the mechanism and its significance of the depression of telomerase activity in HL-60 cells exposed to homoharringtonine (HHT), the semi-quantitative RT-PCR and PCR-ELISA were used to detect the expression of hTERT mRNA and telomerase activity in HL-60 cells, the apoptotic rate of HL-60 cells was assayed with TUNEL. The results indicated that compared with the control, the level of hTERT mRNA synthesis in HL-60 cells treated with HHT at 0.005 - 0.03 micro g/ml for 12 hours did not change significantly, but it reduced obviously at 0.04 micro g/ml and was undetectable at 0.05 micro g/ml. When HL-60 cells incubated with HHT at 0.02 micro g/ml for various hours, the expression of hTERT mRNA did not decrease after 6 - 18 hours and reduced significantly after 24 hours and was undetectable at 30 hours. The tendency for suppression of telomerase activity was consistent with decrease of the expression of hTERT mRNA in HHT-treated HL-60 cells. The apoptotic rate of HL-60 cells was apparently increased with the depression of hTERT mRNA and telomerase activity. In conclusion, the transcription of hTERT mRNA in HL-60 cells can be inhibited by HHT. The relationship between regulation of hTERT mRNA expression and HHT-induced apoptosis is worth investigating furtherly.