M6A Demethylase FTO Promotes The Resistance Of HER2-positive Breast Cancer Cell To Trastuzumab

Background and objectives: Breast cancer ranks first in the incidence of malignant tumors in women,which seriously endangers health.Since Trastuzumab(trade name Herceptin)has been used in the treatment of human epidermal growth factor receptor2(HER2)positive breast cancer,patients have benefited a lot;however,it has been widely used in clinical practice.About half of HER2-positive breast cancer cases will develop drug resistance,leading to tumor progression or recurrence.M6 A methylation is an epigenetic modification that occurs widely in mammalian RNA.Fat mass and obesity-related genes(FTO)are one of the m6 A demethylases,which are involved in the development of ontogeny,tumorigenesis,and other physiology and pathology.process.This article aims to explore whether FTO is related to the resistance of HER2-positive breast cancer to trastuzumab therapy,and to explore the effect of the self-developed new anti-HER2 antibody HuA21 on the proliferation of drug-resistant breast cancer cells.Materials and Methods: Prepare trastuzumab resistant cell line BT474/TR,observe the morphology of BT474/TR and BT474 cells under optical microscope,detect cell proliferation by MTT method,detect the expression of proliferation-related antigen Ki67 by immunofluorescence method,detect cell cycle by flow cytometry,and q PCR And Western blot method was used to detect the expression of m6A-related enzymes FTO and METL3.Results: BT474/TR showed pyknosis of the nucleus,the pseudopodia disappeared,and the cell proliferation rate decreased.Trastuzumab treatment of BT474 cells 0d,4d,8d and BT474/TR cells,Ki67 expression gradually decreased,cell cycle S phase cell proportion also gradually decreased(P<0.05),FTO expression gradually increased(P<0.05),but There is no difference in METTL3 expression.The FTO inhibitor MA2 promoted the proliferation of BT474/TR cells and increased the sensitivity of cells to trastuzumab treatment(P<0.05).HuA21 antibody has an inhibitory effect on the proliferation of BT474/TR cells(P<0.05),and the combination of MA2 and trastuzumab has a better inhibitory effect on BT474/TR cells(P<0.05).Conclusion: There is a correlation between the resistance of HER2-positive breast cancer cell to trastuzumab and FTO gene expression,inhibition of FTO activity can enhance the sensitivity of drug-resistant cells to trastuzumab treatment.