Abstract:
Objective To construct an aromatase-overexpressing breast cancer cell model and observe the real-time apoptosis of breast cancer cells induced by the aromatase inhibitor, letrozole.
Methods The lentivirus-mediated gene transfection method was used to construct the MCF-7-VC3AI and ZR7530-VC3AI cell lines, which stably expressed the apoptotic fluorescent indicator protein VC3AI. Simultaneously, letrozole-induced apoptosis models of the MCF-7-VC3AI and ZR7530-VC3AI breast cancer cell lines were also constructed. Real-time quantitative PCR (qPCR) and Western blot methods were used to detect the mRNA and protein levels of aromatase in the cells. Cell proliferation ability was measured using MTT. The proliferation of cells in vitro under testosterone, estradiol, or letrozole combined with testosterone treatments were also observed.
Results qPCR results showed that the expression of the aromatase mRNA was significantly higher in both the MCF-7 and ZR7530 cell models when compared to the MCF-7-VC3AI and ZR7530-VC3AI cell models. Western blot results showed that the expression of the aromatase protein was significantly increased in both cell models. MTT assay results showed that the proliferation of a cell model could be promoted by testosterone and estrogen stimulation. Under 100 nmol/L testosterone, the proliferation rate of over-expressed aromatase MCF-7-VC3AI cells was about 1.2 times than that of the control group (P < 0.01) and the proliferation rate of ZR7530-VC3AI cells was about 1.5 times than that of the control group (P < 0.01). However, letrozole inhibited the proliferation induced by testosterone in a dose-dependent manner. Under the effect of letrozole at 10 μmol/L, the proliferation rate of over-expressed aromatase MCF7-VC3AI cells was 80% of the control group(P < 0.05), while the proliferation rate of over-expressed aromatase ZR7530-VC3AI cells was 68% of the control group (P < 0.05).
Conclusions The successful establishment of cell models that can detect letrozole-induced apoptosis provides an important foundation for further investigating the mechanism of letrozole.