N-glycans Of Glycoprotein Are Associated With Drug Resistance Of Human Breast Cancer

Drug resistance of the breast cancer cell leads to the failure of chemotheraphyduring treating human breast cancer. These tumor cells could resist antineoplastic drugswith different structures and mechanisms, which is termed multidrug resistance（MDR）.So how to reverse the multidrug resistance of the breast cancer cell become animportant research in the therapy of human breast cancer. Recent studies have shownthat N-glycans play an important role in drug resistant of tumor. However, themechanism of N-glycans to drug resistance is not well understood.Objective: To identify the relationship of N-glycans to drug resistance of thebreast cancer cell and to explore the prospect of a potential diagnose biomarker and anew therapeutic approach of tumors.Methods: Adriamycin was added to MCF-7cell cultures in stepwise increasingconcentrations to develop a drug resistant cell subline （MCF/ADR）. We compared theN-glycan of MCF-7with MCF/ADR cells using two glycan profiling tools：（1） UsingFITC–lectin binding combined Flow cytometry assay，we detected the difference ofglycan profiling between MCF-7and MCF/ADR cell lines.（2） Using MS analysis, wedetected the difference of N-glycan composition between MCF-7and MCF/ADR celllines; We detected the changes of the sensitivity to chemotherapeutic drugs dramaticallyboth in vitro and in vivo after the N-glycan regulation by tunicamycin（TM） applicationor PNGase F treatment in MCF/ADR cells:（1） The changes of the sensitivity tochemotherapeutic drugs was measured using an MTT assay.（2） Antitumor activityassay in vivo.Results:（1） FITC–lectin binding profiles and N-glycan composition of MCF-7andMCF/ADR cell lines are different. The α-Man and fluorescence are increased inMCF/ADR cells compared to which in MCF-7cells. （2） Compared with MCF/ADR groups in the absence of TM or PNGase F, asignificant reduction of IC₅₀of anticancer drugs was observed and increased with theconcentration of tunicamycin and PNGase F treatment time, the IC₅₀values ofanticancer drugs reduced.（3） Compared with MCF/ADR groups in the absence of TM or PNGase F, asignificant reduction of mean tumor weight of deglycosylation tumors was observed. Inthe tunicamycin treated MCF/ADR line, the IR of adriamycin were9.94%,14.45%,22.29%,37.30%. In the PNGase F treated MCF/ADR cells, the IR of adriamycin were9.94%,16.88%,27.46%,40.37%.Conclusion:（1） FITC–lectin binding profiles and N-glycan composition of MCF-7andMCF/ADR cell lines are different. N-glycans of cell membrane may be associated withdrug resistance of breast cancer cells.（2） The N-glycan regulation by tunicamycin （TM） application or PNGase Ftreatment in MCF/ADR cells increased the sensitivity to chemotherapeutic drugsdramatically.