Bosutinib Enhance Radiosensitivity Of Breast Cancer Cells By Inhibiting EIF4G1

Objective:To identify approved drugs based on eIF4G1,enhancing radiosensitivity of breast cancer cells and clarify the underlying mechanism of eIF4G1 as one of the regulators of cellular response to radiotherapies.Methods:（1）GSE41627,a subdatasets of radiosensitized gene expression signatures of irradiated eIF4G1-silenced cells,was obtained from the GEO database through the label similarity comparison of gene expression profile.And existed drugs from public databases were integrated and enrichment scores were calculated to describe similarity between them.Compounds with positive enrichment scores were selected and ranked;（2）The toxic effect of potential drugs on human breast cancer cells was assayed by CCK-8 kit,and to find the dominant drug;（3）CCK-8 kit assay for the effect of dominant drug on the proliferation of three human breast cancer cells,the further,Cell clone formation assay detects cell viability;（4）We also detection whether the dominant drug can enhance radiosensitivity of MDA-MB-231 and MCF-7 cells,which were observed by colony formation assay;（5）Apoptosis was detected by Annexin V,FITC;cell cycle was detected by flow cytometry;（6）The expression levels of eIF4G1,LC3βandγH2AX in MX-1,MCF-7 and MDA-MB-231 cells were detected by Western Blot;Results:（1）A total number of 2089 entries of compounds including their maximum and average ES evaluated by comparison with eIF4G1-silenced cells at both 96h and 144h after radiation.We further calculated maximum and average value of ES for each candidate.and three drug candidates were selected:Bosutinib、Bifonazole、Isosorbide Mononitrate;（2）We found that these three candidate drugs have different chemosensitivity for breast cancer.Isosorbide is the least sensitive to human breast cancer cells,and its half-inhibitory concentration(IC₅₀)is more than 1 mmol/L.Bosutinib is the most sensitive to human breast cancer cells,and the half-inhibitory concentration(IC₅₀)is about 0.5μmol/L;the half-inhibitory concentration(IC₅₀)of Bifonazole on human breast cancer cells is about 50μmol/L;（3）Bosutinib can inhibit the growth of these three human breast cancer cells（MX-1,MDA-MB-231,MCF-7）,and shows dose-dependent effect;（4）The combination of Bosutinib and irradiation could affect the growth of human breast cancer cells and significantly inhibit the cell proliferation.the control group,the drug group and the irradiation group with the difference between them being statistically significant（P<0.01）;（5）Bosutinib increased apoptosis of MCF-7 cells,but has no effcts on MDA-MB-231 cells.Combined with irradiation,it can get higher apotosis rate of MCF-7 cells.This phenmenon can’t be observed in MDA-MB-231 cells;when we only applied Bosutinib to the MDA-MB-231 and MCF-7 cells without influlence its cell cycle.However,combined with irradiation,it can be observed that it could impaire the G2/M phase arrest caused by irradiation;（6）Bosutinib applied for breast cancer cells,which could decrease the expression of eIF4G1 and increased the expression of LC3βII/I andγH2AX.Conclusion:By the label similarity comparison of gene expression profile and combined with CCK-8 kit assay,we select Bosutinib which as a superior drug for improving radiosensitivity of breast cancer.It may be achieved by eIF4G1,which regulates key proteins in cell cycle,apoptosis,autophagy and other related pathways.The study combined with big data analysis,drug prediction,and targeted treatment strategies.eIF4G1 is selectively involved in the regulation of DNA double-strand break damage translation initiation,which will evaluate the mechanism of the radiosensitization of drugs from a new perspective.