Essential Role For Long Non-coding RNA POU3F3 Containing Exosomes In Breast Cancer With Neoadjuvant Chemotherapy Resistance

Objective Neoadjuvant chemotherapy of breast cancer is an important part of comprehensive treatment of breast cancer and plays a significant role in reducing tumor staging,creating surgical opportunities and improving survival rate.However,drug resistant to tumor often affects chemotherapy,leading to the failure of breast cancer treatment.Therefore,it is very important to find a biomarker that can predict the chemosensitivity of breast cancer.This topic examines the expression of lncRNA in neoadjuvant chemotherapy tissue samples of breast cancer and aims to find a meaningful lncRNA for neoadjuvant chemotherapy.Objective to explore the role and mechanism of lncRNA in the chemoresistance of breast cancer mediated by exosomes,and to find valuable prognostic indicators and individualized chemotherapy plans for neoadjuvant chemotherapy of breast cancer.Methods ①The high-throughput sequencing was used to compare and analyze the expression level of lncRNA and mRNA in the breast cancer tissues of the same individual after neoadjuvant chemotherapy.②qRT-PCR was used to detect the expression of lncRNA POU3F3 in 20 cases of pathologically complete remission(pCR)and 16 cases of non-pathological complete remission(NpCR).③qRT-PCR was used to detect the expression of lncRNA POU3F3 in the drug resistant cell line MDA-MB-231/DOX and the parent MDA-MB-231.④Exosomes were extracted and the were identified by electron microscopy and nanoparticle size detection,the positive percentage of exosomes were measured by flow cytometry to determin the purity of the exosomes.⑤qRT-PCR was used to detect the expression of lncRNA POU3F3 in the exosomes of MDA-MB-231/DOX cell and the exosomes of MDA-MB-231 cells.⑥SiRNA sequences were used to interfere with the expression of lncRNA POU3F3,and wound healing was detected cell migration ability.Results ①The expression level of lncRNA POU3F3 in neoadjuvant chemotherapy NpCR group was higher than that in pCR group.②The expression level of lncRNA POU3F3 in the drug-resistant cell line MDA-MB-231/DOX was higher than that of the parent MDA-MB-231.③The expression level of lncRNA POU3F3 in MDA-MB-231/DOX cell exosomes was higher than that of MDA-MB-231 cell exosomes.④Interference with lncRNA POU3F3 expression inhibited the migration of MDA-MB-231/DOX cells.Conclusion LncRNAPOU3F3 may influence the development of chemoresistance in breast cancer through exosome-mediated,and have an impact on cell migration;IncRNA POU3F3 is an important marker for predicting the efficacy of neoadj uvant chemotherapy in breast cancer.