Effects Of CDK7 Inhibitor THZ1 On The Proliferation Of Triple-negative Breast Cancer Cell Lines And The Study Of Its Mechanism

Research objectives:To explore the effects of cyclin-dependent kinase 7(CDK7)inhibitor THZ1 on the proliferation of triple-negative breast cancer cell lines and its underlying mechanisms.Research methods:(1)The cell viability test(CCK),cell proliferation counting test were used to detect the effect of the different concentrations of CDK7 inhibitor THZ1(0n M、12.5n M、25n M、50n M、100n M、200n M、400n M)on the cell viability and proliferation ability of p53 mutant triple-negative breast cancer cell lines Hs-578T,p53 wild-type triple-negative breast cancer cell lines DU4475 and hormone receptor positive breast cancer cell lines MCF-7.(2)Western blot was used to detect the effects of different concentrations of THZ1(0n M,12.5n M,25 n M,50 n M,100 n M)or the same concentration of THZ1 for different times(12h,36 h,48h)on p53 expression in p53 mutant triple-negative breast cancer cell lines Hs-578T,p53 wild-type triple-negative breast cancer cell lines DU4475,and hormone receptor-positive breast cancer cell lines MCF-7.(3)Western blot was used to detect the effects of using shRNA to directly down-regulate the expression of CDK7 on the expression of p53 in p53 mutant triple-negative breast cancer cell lines Hs-578T,p53 wild-type triple-negative breast cancer cell lines DU4475,and hormone receptor-positive breast cancer cell lines MCF-7.(4)The cell proliferation counting experiment was used to detect the effects of using si RNA to directly interfere with the expression of mutant and wild-type p53 on the proliferation of p53 mutant triple-negative breast cancer cell lines Hs-578T,p53 wild-type triple-negative breast cancer cell lines DU4475,and hormone receptor-positive breast cancer cell lines MCF-7.Results:(1)Cell viability testing experiments showed that the CDK7 inhibitor THZ1 had a half inhibitory concentration of 30.54 n M,139.7n M and 209.3 n M on the p53 mutant triple-negative breast cancer cell lines Hs-578T,p53wild-type triple-negative breast cancer cell line DU4475 and hormone receptor-positive breast cancer cell lines MCF-7,respectively.(2)The results of cell proliferation counting test showed that the proliferation of Hs-578T cells treated with 25 n M and 50 n M THZ1 showed a decreasing trend within 48 h after treatment,while the proliferation of DU4475 cells and MCF-7 cells treated with 25 n M and 50 n M THZ1 still showed a continuous increasing trend within 48 h after treatment.(3)Western blot experiments showed that treatment with the CDK7 inhibitor THZ1 decreased the expression of mutant p53 protein in the p53 mutant triple-negative breast cancer cell line Hs-578T,while the expression of wild-type p53 protein increased in the corresponding p53 wild-type triple-negative breast cancer cell line DU4475 and hormone receptor-positive breast cancer cell line MCF-7 after treatment with THZ1.The difference is statistically significant.(4)After the expression of CDK7 was inhibited by sh RNA,western blot experiments showed that the expression of mutant p53 protein in the p53 mutant triple-negative breast cancer cell line Hs-578T was decreased,while the expression of wild-type p53 protein increased in the corresponding p53wild-type triple-negative breast cancer cell line DU4475 and hormone receptor-positive breast cancer cell line MCF-7.The difference is statistically significant.(5)The proliferation counting experiment showed that the proliferation of p53 mutant triple negative breast cancer cell line Hs-578T was inhibited after interfering with the expression of mutant p53 using si RNA,while the proliferation of p53 wild-type triple negative breast cancer cell line DU4475 and hormone receptor positive breast cancer cell line MCF-7 was almost unaffected after interfering with the expression of wild-type p53 using si RNA.The difference is statistically significant.Conclusion:(1)The CDK7 inhibitor THZ1 has a stronger ability to inhibit the proliferation of p53 mutant triple-negative breast cancer cell lines than p53wild-type triple-negative breast cancer cell lines and hormone receptor-positive breast cancer cell lines.(2)CDK7 inhibitors can inhibit the proliferation of p53 mutant triple-negative breast cancer cell lines by inhibiting the expression of mutant p53.