Research On The Role Of CDKL1 In Drug Resistance For Estrogen Receptor-Negative Breast Cancer Cells

Globally,breast cancer is one kind of cancer with high morbidity and mortality in women.Due to improper diagnosis and chemotherapy sensitivity problems,the therapeutic effect of breast cancer remains unsatisfactory.Therefore,researchers try to explore reliable predictive biomarkers to advance the targeted treatment of breast cancer.It has been reported that the expression of CDKL1 is up-regulated in breast cancer tissues,and the inhibition of CDKL1 may increase the sensitivity of cells to chemotherapeutic drugs.However,the role of CDKL1 in the regulation of tumor cell cycle and its related signaling pathway remains unclear.The purpose of this project is to study the expression level of CDKL1 in drug-resistant and non-drug-resistant breast cancer cells as well as its potential association with breast cancer resistance.At the same time,the SKBR-3 cell line was induced by tamoxifen to screen new breast cancer resistant cell lines in order to compare the expression level of CDKL1 in drug-resistant and non-drug-resistant breast cancer cell lines characterized with estrogen receptor-negative in subsequent studies.In this experiment,expression levels of CDKL1 protein in breast cancer cells for MDA-MB-231,MCF-7,and breast cancer tamoxifen-resistant cell line OHTR-T1000were determined by Western Blotting.The viability of breast cancer cells was determined by MTT assay.Meanwhile,the expression levels of CDKL1 protein in different breast cancer cells were analyzed and compared with the tolerance level of tamoxifen in breast cancer cells.Experimental observations suggest that there is a significant difference in the expression of CDKL1 in estrogen receptor-positive and estrogen receptor-negative breast cancer cells,but it is still not clear to conclude whether the level of resistance in breast cancer cells is correlated to the difference of CDKL1 expression in various cell lines.The follow-up study needs to continue to expand the detection range of the cell lines and repeat the test before a more reliable conclusion obtained.Moreover,in order to further study the molecular mechanism of CDKL1 in drug resistance of breast cancer as well as CDKL1 expression levels in estrogen receptor-negative breast cancer cells,the low to high concentrations of tamoxifen were treated for SKBR-3 cell line.SKBR-3 cell line was induced for more than half a year to obtain SKBR-3 tamoxifen-resistant cell line(IC₅₀ value of 43.42±6.05?g/ml),which is 1.7 times for that of the normal SKBR-3 cell line(IC₅₀ of 25.48±2.94?g/ml).This result is statistically significant.Through Western Blotting detection,the expression level of CDKL1 in SKBR-3 tamoxifen-resistant cell is higher than that of the normal SKBR-3 cell,which indicates that high expression of CDKL1 may be related to drug resistance for estrogen receptor-negative breast cancer cells,but further confirmation is still required in this kind of cells.The SKBR-3 tamoxifen-resistant cell line is a basis to investigate the molecular mechanisms of CDKL1 and breast cancer resistance based on the signaling pathway.