RESUMO
Objective To study the expression characteristics of Let-7 genes in breast cancer.Methods Twenty-eight patients with breast cancer were randomly selected,and their cancer tissue and adjacent normal tissue were collected.TRIzol was used to extract the total RNA and real-time quantitative PCR was used to detect the relative gene expression levels.Results The expression of precursor Let-7 in cancer tissue was (9.65 ± 2.31),which was lower than that in normal tissue (10.05 ± 2.81),P =0.048.Precursor Let-7 had dependence relationship with the long menstruation (b =0.816,P =0.029).The menarche age showed a positive correlation with precursor Let-7 in normal tissue (r =0.502,P =0.048) and a negative correlation in cancer tissue (r =-0.484,P =0.049) Conclusions The expression of precursor Let-7 in cancer tissue is lower than that in normal tissue.The period of menstruation is a protective factor to breast cancer.