Effect Of Letrozole On The Growth Of Human Uterine Leiomyoma Cells In Vitro

Objective:To investigate the expression of aromatase cytochrom P450mRNA,the secretion of estradiol,caspase-3 and the suppressive effect of aromatase inhibitor letrozole on the proliferation and apoptosis of uterine leiomyoma cells in vitro.Our purpose was to investigate the effects of letrozole on the growth of human Uterine leiomyoma cell line in vitro and its mechanism of action.Methods:Uterine leiomyoma cells were cultured in vitro,after the action of of letrozole with different concentration,MTT was used to examine the proliferative activity of uterine leiomyoma cells, RT-PCR was used to determine the expression of the aromatase cytochrom P450 and caspase-3mRNA,and the concentration of estradiol in media supernatant was measured by radioimmunity,leiomyoma cells apoptosis was assessed by flow cytometry.Results:1.Successful people cultivate human uterine leiomyoma cells in vitro and identified by immunocytochemistry.2.Blank control group uterine leiomyoma cells grow well.There was no significant difference between solvent control group and blank control group(P＞0.05).Letrozole in a dose-time -dependent manner inhibited leiomyoma cell proliferation.The effect of 24h role was not obvious(P＞0.05),48h increased at start steadily(P＜0.05),72h at the most significant inhibitory effect(P＜0.01),96h inhibitory rate had stabilized,efficacy tended to saturation.6×10^-8mol/L of letrozole had no effect on the expression of aromatase cytochrom P450 mRNA,and estradiol synthesis and the proliferative activity in uterine leiomyoma cell(P＞0.05).However, 6×10^-7mol/L～6×10^-6mol/L of letrozole could down-regulate the expression of aromatase cytochrom P450,and to inhibit estradiol synthesis and the proliferation activity of uterine leiomyoma cells(P＜0.05).Furthermore,the inhibition were shown to decline gradually along with the increase in the concentrations of letrozole. 3.In the control group there was low expression of caspase-3 mRNA and nosignificant apoptosis situation.After the action of of letrozole with different concentration,there was different levels of apoptosis occur.Compared with the control group,6×10^-8mol/L of letrozole increased apoptosis rate with a slight increase in caspase-3 mRNA expression,but the difference was not statistically significant(P>0.05);with higher concentrations,apoptosis rate gradually increased,caspase-3 mRNA expression gradually enhanced(P<0.05).And 6×10^-7mol/L group and 6×10^-6mol/L group,there were significant differences(P<0.05).Conclusion:1.Uterine leiomyoma cells in vitro can express P450arom mRNA,and take advantage of P450arom to synthetic E2.E2 may induced the emergence and growth of leiomyoma cells in vitro environment.2.Letrozole can inhibit proliferative activity of leiomyoma cells in vitroin a dose-time -dependent manner.It may be competive aromatase activity site with the endogenous substrate,antagonize expression of aromatase and reduce the formation of estrogen.3.To be able to up-regulate caspase-3 expression,promote apoptosis of leiomyoma cell in a dose-dependent manner.