Effect And Mechanism Of Benzo[a]Pyrene On Genetic Damage In MCF-7 Breast Cancer Cell

Objective: To investigate the effect of benzo(a)pyrene(B[a]P)on cell cycles,we using human breast cancer cell line MCF-7 exposure to different concentrations B[a]P;To explore genetic damage and related mechanisms induced by B[a]P,as well as getting a clear dose-related effects of B[a]P,we study the effect of B[a]P on DNA or chromosome by B[a]P exposure to human breast cancer cell line MCF-7 at various cell cycles in vitro.Methods : 1.To analyse various cell cycles,the content of DNA in MCF-7 breast cancer cells cultured at different time points were detected by flow cytometry(FCM).2.To analyse effection on cell cycles,changes of DNA content in MCF-7 breast cancer cells in various cell cycles exposure to different concentrations of B[a]P after 24 h were detected by flow cytometry.3.The level of DNA damage of MCF-7 breast cancer cells in various cell cycles with different concentrations of B[a]P were measured by alkaline single-cell gel electrophoresis(comet)assay.4.The chromosome damage of MCF-7 breast carcinoma cells in different cell cycles with different concentrations of B[a]P were measured by cytokinesis-block micronucleus assay(CBMN).5.The molecular structure destruction of B[a]P with different concentrations on MCF-7 breast cancer cells in G0/G1-phase were investigated by attenuated total reflection Fourier-transform infrared(ATR-FTIR)spectroscopy and multivariate analysis.Results: 1.Most of the cells were in a certain period(G0/G1-phase,S-phase and G2/M-phase)when MCF-7 breast cancer cells were cultured at different time.2.Low-dose B[a]P block the cells in G2/M-phase,while the middle-or high-dose B[a]P block in G0/G1 phase,when MCF-7 breast cancer cells exposure to different concentrations B[a]P after 24 h.3.Compared with the control group in the comet assay,B[a]P can increase the comet tail length(CTL)(?m)in a dose-effect manner(P<0.05)and has more significant effection on S-phase and G2/M-phase.4.Compared with the control group in CBMN,the ratio of micronuclei(‰)(MNi)was proved to be increased and accompanied by a rise of the concentration of B[a]P exposure to MCF-7 breast cancer cells in various cell cycles,as well as more influence on S-phase.5.Applying ATR-FTIR spectroscopy with subsequent multivariate analysis to investigate that B[a]P with different concentrations exposure to MCF-7 breast cancer cells in G0/G1-phase revealing a dose-related effect.Compared with the control group,both 1-D and 2-D scores plots showed that the spectral point of 10-5 mol·L-1 B[a]P presented a greater degree of separation than 10-6 mol·L-1 B[a]P in G0/G1-phase.ANOVA tests demonstrated that all treatment groups are significantly different from the control group(P<0.0001).B[a]P had a influence on the structure of DNA/RNA,secondary structures of proteins,protein phosphorylation,lipid and glycogen in MCF-7 breast carcinoma cells in G0/G1-phase.The main biological alteration was resulted by 10-5 mol·L-1 B[a]P in DNA/RNA,secondary structures of protein(Amid II),protein phosphorylation,lipid and glycogen,while 10-6 mol·L-1 B[a]P had resulted in DNA/RNA,secondary structures of proteins(Amid I and Amid II),lipid and glycogen.Moreover,10-5 mol·L-1 B[a]P had more apparent effect on structure of DNA/RNA than 10-6 mol·L-1 B[a]P.Conclusions: The genetic damage of MCF-7 breast cancer cells can be induced by B[a]P in different cell cycles with a concentration-dependent manner,which function mechanism is arresting cell cycles and effecting on chromosome or DNA.