Effect Of Aloe Emodin On Telomerase Activity In The Breast Cancer Cells

Objective: To study the effects of aloe emodin(AE)on telomerase activity,telomerase catalytic subunit hTERT(human telomerase reverse transcriptase)and its regulatory factors E2F1 and c-Myc in the two breast cancer cells.Methods: Cells were treated with different concentrations of AE(0,10,30 and 50 ?mol/L)for 48 h.The activity of telomerase was measured by TRAP(telomere repeat amplification protocol).RNA was extracted from each treatment,the expression of hTERT gene mRNA was detected by SYBR Green quantitative real-time PCR(qPCR).The protein levels of hTERT,c-Myc and E2F1 in the treated cells were analyzed by Western blot.The effects of different concentrations of AE on methylation of hTERT gene promoter were detected by BSP(bisulfite sequencing PCR).Results: Compared with the control,the telomerase activities of breast cancer cells were significantly decreased when treated by AE.AE inhibited the telomerase activities and the inhibition rate was raised with the increasing concentration of AE.As revealed by the qPCR,AE could inhibit the expression of hTERT mRNA in the breast cancer cells when compared the treatments with the control.The inhibitory effect enhanced as the AE concentration increased.The Western blot showed that AE inhibited the expression of hTERT and telomerase regulatory factor c-Myc as well as that of E2F1 in breast cancer cells.The inhibitory effect and drug concentration were positively correlated.When treated by 10 ?mol/L AE for 48 h,the methylation levels of the hTERT gene promoter decreased as compared with the control,as indicated by BSP.Conclusions: The inhibition of telomerase activity in MDA-MB453 and MCF7 breast cancer cells by AE is related to the reduction of hTERT promoter methylation level,the decreased expressions of telomerase catalytic subunit hTERT and the regulatory factor c-Myc,and the increased expression of E2F1.