CircSTIL Mediates Pirarubicin Inhibiting The Malignant Phenotype Of Triple-Negative Breast Cancer And The Primary Discussion Of Its Clinical Significance

Breast cancer is the most common malignant cancer among women.In all subtypes of breast cancer,triple-negative breast cancer(TNBC)has a high degree of malignancy and poor prognosis.TNBC is not sensitive to endocrine therapies and targeted therapies,only chemotherapy can be used.The current clinical medication guidelines recommend that TNBC patients receive neoadjuvant chemotherapy before surgery,and the commonly used chemotherapeutics are anthracycline drugs such as pirarubicin(THP).However,chemotherapy drugs have limited efficacy and strong side effects in treating TNBC patients,so it is urgent to find new drug treatment targets for TNBC.Circular RNA(circRNA)is a kind of covalently closed circular endogenous RNA molecule formed by the back-splicing mechanism of pre-m RNA,which can play a biological role in organisms by participating in the regulation of gene expression.More and more studies have proved that circRNA plays an important role in cancer diagnosis,treatment,and prognosis.However,the role circRNA plays in TNBC and the relationship between THP and circRNA needs to be explored.Exosomes are a kind of membranous extracellular vesicles secreted by cells,which are widely distributed in body fluids and can carry and transmit a variety of biomolecules including circRNAs,thereby exerting biological functions and serving as cancer diagnostic or prognostic biomarkers.Whether circRNA in plasma exosomes of patients has potential value as a diagnostic and prognostic biomarker for TNBC needs to be studied urgently.This study aims to screen target circRNAs related to TNBC tissue and THP treatment.Through in vitro experiments and clinical analysis,a variety of experimental methods are used to explore circSTIL-mediated THP inhibition of TNBC malignant phenotype and its clinical significance in patients’ plasma exosomes.In order to provide new therapeutic targets,diagnostic biomarkers,and prognostic biomarkers for TNBC.This study is divided into the following 3 research parts:(1)Bioinformatics analysis of circRNA gene chip and identification of expression and molecular characteristics of circSTILIn this study,the results of circRNA sequencing in MDA-MB-231 cells interfered by THP in our research group intersected with the results of circRNA sequencing in TNBC tissue in the public database.Finally,circSTIL was used as a research object,which was significantly down-regulated in THP-intervened MDA-MB-231 cells,and was significantly downregulated in TNBC tissues.At the cellular level,it was found that after THP intervened in MDA-MB-231 cells,the expression of circSTIL was significantly downregulated,which was consistent with the results of THP intervening MDA-MB-231 cell chips;circSTIL was specifically highly expressed in TNBC cells.In the patient’s tissues,it was confirmed that circSTIL was highly expressed in TNBC tissues,which was consistent with the sequencing results of TNBC tissues;circSTIL was specifically highly expressed in TNBC tissues.Sanger sequencing,agarose gel electrophoresis,ribonuclease R assay,and actinomycin D assay all proved that circSTIL has a reverse splicing ring structure and high stability.circSTIL was mainly distributed in the cytoplasm,suggesting that it may play a role in the cytoplasm.(2)The role of circSTIL in THP inhibiting the proliferation,migration,and invasion of MDA-MB-231 cells and promoting cell apoptosisOverexpression of circSTIL can promote the proliferation,migration,and invasion of MDA-MB-231 cells and inhibit apoptosis;knockdown of circSTIL has the opposite effect.THP can inhibit the proliferation,migration,and invasion of MDA-MB-231 cells and promote cell apoptosis;while the overexpression of circSTIL can reverse the above effects of THP to some extent.It shows that THP can inhibit the malignant phenotype of MDA-MB-231 cells by down-regulating circSTIL.(3)Expression of circSTIL in plasma exosomes of breast cancer patients and its potential biomarker of TNBCPlasma was collected from different breast cancer patients,and plasma exosomes were extracted,isolated,and identified.It was proved that circSTIL was highly expressed in plasma exosomes of TNBC patients;down-regulated expression.In the plasma exosomes of TNBC patients,ROC curve analysis showed that circSTIL had diagnostic value in differentiating TNBC patients;high expression of circSTIL was associated with poorer DFS in patients.It was suggested that circSTIL could serve as a potential diagnostic and prognostic biomarker for TNBC.In summary,this study reached the following conclusions:(1)Circ STIL(hsa＿circ＿0000069)was obtained through bioinformatics analysis of THP intervention MDA-MB-231 cell gene chip and TNBC tissue gene chip(GSE101123)and proved its specificity in TNBC cell lines and tissues High expression.(2)In vitro studies confirmed that overexpression of circSTIL could promote the proliferation,migration,and invasion of MDA-MB-231 cells and inhibit apoptosis,while the results of knocking down circSTIL were the opposite.(3)THP inhibits the proliferation,migration,and invasion of MDA-MB-231 cells and promotes apoptosis,the effects of which are mediated through circSTIL.(4)circSTIL is highly expressed in plasma exosomes of TNBC patients,and has diagnostic value in distinguishing TNBC from non-TNBC patients;circSTIL is associated with poor prognosis in TNBC patients.