The Effects Of TRIM24 And P27 On Biological Behavior Of Triple-Negative Breast Cancer MDA-MB-231 Cell Line

Background:Breast cancer is the most common malignant tumors,of which morbidity ranks first in the world,seriously impacts on women’s health.Triple negative breast cancer(TNBC)is a special kind of breast cancer subtypes,mostly in young women,accounting for 15% to 20% of all breast cancer,which refers to the one that estrogen receptor(ER)、 progesterone receptor(PR)and human epidermal growth factor receptor 2(HER2)are both negative.TNBC is not sensitive to endocrine therapy and targeted therapy because of the negative expression of the three receptors.Chemotherapy is the main treatment,but resistance to chemotherapy appeared soon.Therefore,the study of the molecular mechanisms of differentiation and proliferation of breast cancer recurrence and metastasis of breast cancer progression,treatment and prognosis of the disease has it’s significance.TRIM24(tripartite motif 24)is also known as transcriptional regulation factor 1,which plays an important role in regulating cell growth,proliferation,differentiation and tumor formation.Previous studies have shown that TRIM24 is overexpressed in trinegative breast cancer cell lines,but the specific mechanism is unclear.P27 gene is an important gene regulating cell cycle and inhibiting cell division,which is mainly combined with cell cycle protein to exert inhibiting effect on cell cycle protein dependent kinase.Studies have shown that P27 has low expression in trinegative breast cancer cell lines,and its low expression is associated with poor clinical prognosis.It has been confirmed that TRIM24 is related to P27 in lung cancer cell lines,but no relevant reports have been reported in breast cancer.Objective: The purposes of this study is to clarify the effects of TRIM24 gene on biological behaviors in triple negative breast cancer MDA-MB-231 cell line,including the cell migration,apoptosis,proliferation.The interaction between TRIM24 and P27 in triple negative breast cancer was further discussed,so as to provide new ideas for the treatment of triple negative breast cancer.Research methods:(1)By the application of siRNA transient transfection technique,the si TRIM24,siP27 and siNegative control are transfectd respectively into triple negative breast cancer MDA-MB-231 cell line,thus interfer the expression of TRIM24 gene and P27 gene.(2)The mRNA levels and protein levels of TRIM24 and P27 in each group were detected by RT-PCR and Western Blot.(3)The cell migration of the breast cancer cell was detected by the use of the scratch test,after the si TRIM24,siP27 are transfectd respectively into breast cancer cell.(4)The apoptosis detection is carried out by flow cytometry for each transfection group and negative control group.(5)The MTT method was used to detect the cell proliferation of the breast cancer cell in siTRIM24 and(or)siP27 transfection group,si NC group.Results:1.The results of RT-PCR showed that compared with the siNC group in the breast cancer MDA-MB-231 cell line,the mRNA expression level of P27 is up-regulated and the expression of TRIM24 is down-regulated,after the silence of TRIM24 gene.But the m RNA expression level of TRIM24 is up-regulated and the expression of P27 gene is down-regulated,after the silence of P27 gene.2.Western Blot results suggest: in breast cancer MDA-MB-231 cells,compared with siNC group,the protein expression level of P27 is down-regulated and the expression of TRIM24 is up-regulated,after the silence of P27 gene.But the protein expression level of TRIM24 is down-regulated and the expression of P27 gene is upregulated,after the silence of TRIM24 gene.3.The results show that compared with siNC group,the cell migration rate of the siP27 group is increased,while the cell migration rate of the siTRIM24 group and the combined transfection group is decreased,and the cell migration rate of the siTRIM24 group is lower than that of the combined transfection group.4.Flow cytometry test detection: compared with siNC transfection group,the apoptosis rate of siTRIM24 group is increased,while the cell apoptosis rate of the siP27 group and the combined transfection group is decreased,and the cell apoptosis rate of the siP27 group is lower than that of the combined transfection group.5.MTT assay shows: compared with the siNC group,the cell proliferation rate of the siP27 group is increased,while the cell migration rate of the siTRIM24 group and the combined transfection group is decreased,and the cell migration rate of the siTRIM24 group is lower than that of the combined transfection group.Conclusion:1.After TRIM24 gene silence,siTRIM24 can increase the expression of mRNA molecule level and protein level of P27 gene in breast cancer MDA-MB – 231 cell lines,on the contrary,After P27 gene silence,siP27 can also increase the expression of TRIM24 gene.These suggest possible TRIM24 by promoting the degradation of P27 gene to regulate the expression of cell cycle related proteins,thereby promoting the development of breast cancer.2.Silencing TRIM24 gene can lead to the increase of apoptosis of MDA-MB-231 cell lines,and the decrease of cell proliferation and cell migration ability,which have a significant influence on the biological behavior of cell.3.Silencing P27 gene can lead to the decrease of apoptosis of breast cancer MDA-MB-231 cell lines,increase of cell proliferation and cell migration,which play an important role in the development of three-negative breast cancer.