Activin A Activates P38 To Promote Proliferation And Migration Of Human Inflammatory Breast Cancer SUM149 Cells

Inflammatory breast cancer(IBC)accounts for 1% to 6% of breast cancer cases,but it is a type of breast cancer with the worst prognosis because of its easy metastasis and insensitivity to endocrine therapy and targeted therapy.Activin A(activin A,Act A)is a member of the transforming growth factor-β superfamily,as a multifunctional cytokine,it can participate in various biological processes through paracrine and autocrine mechanisms.Studies have shown that activin A is expressed in various tumor cells,and abnormal activin signal transduction is closely related to the occurrence and development of various tumors.The previous study of our group showed that human breast cancer cell line MDA-MB-231 cells highly expressed activin A,while MCF7 cells low expressed activin A,activin A can promote the migration of MDA-MB-231 cells through the ERK signaling pathway,but no effect on MCF7 cell migration.It shows that activin A has different biological effects on different breast cancer cells.However,the expression and the role of activin A in inflammatory breast cancer cells remain poorly studied.OBJECTIVEThe human inflammatory breast cancer cell line SUM149 cells were selected,and investigated by real-time cell-based assay(RTCA)and Transwell migration assay to regulate the effect of activin A on the proliferation and migration of inflammatory breast cancer SUM149 cells,by detecting the expression of SUM149 cell migrationrelated proteins and signal transduction proteins,to further analyze the mechanism of activin A regulating SUM149 cell migration.METHODSGene differential expression analysis and protein-protein interaction analysis(PPI)between SUM149 cells and normal breast epithelial cells were carried out in GEO database,the m RNA and protein expression levels of related signal proteins were detected by RT-PCR and Western blotting.MTT assay,cell clone formation assay,flow cytometry and RTCA were used to detect cell viability,cell proliferation and cell adhesion.Wound healing assay and Transwell assay were used to detect cell migration.Level of IL-6 in cell culture supernatant was detected by ELISA.The intervention experiment was carried out with small molecule p38 inhibitor SB203580.RESULTSThe gene differential expression in GEO database and PPI analysis showed that the gene expression of activin A and its receptor in SUM149 cells was significantly higher than that in normal breast epithelial cells;and we confirmed that SUM149 cells not only expressed activinβA m RNA,but also expressed activin type I receptor,activin type ⅡA receptor and Smad3 m RNA.Exogenous activin A promoted SUM149 cell viability and proliferation,as well as cell migration,which were inhibited by activin-binding protein FST.However,activin A had no significant effect on the adhesion of SUM149 cells.Further detection showed that activin A could promote the expression of IL-6 m RNA and secretion of IL-6 in SUM49 cells,and its effect could also be weakened by FST.In addition,after activin A treated on SUM149 cells,the cell morphology changed from the original closely connected blunt circle to slender,narrow and nearly spindle shape;activin A significantly promoted the expression of epithelial-mesenchymal transition(EMT)-related proteins N-cadherin,vimentin andα-SMA.The protein levels of Smad3,p-Smad3,Akt,p-Akt,ERK and p-ERK in SUM149 cells were not significantly changed by activin A,however,p38 protein level was significantly decreased and phosphoralated-p38 protein level was significantly increased.The p38MAPK-specific small molecule inhibitor SB203580 can significantly inhibit the migration and EMT of SUM149 cells induced by activin A.CONCLUSIONSIn conclusion,human inflammatory breast cancer SUM149 cells not only express activin A,but are also activin A target cells.Exogenous activin A promoted cell viability and proliferation,IL-6 secretion,induce epithelial-mesenchymal transition(EMT),thereby increasing cell migration ability.Activin A affected the biological behavior of SUM149 cells,which is not related to the classical Smad3 signal,but through the activation of p38 signal.Therefore,the balance of activin A may play a crucial role in the development of human inflammatory breast cancer,and the inhibition of p38 signaling pathway may become a potential therapeutic target for inflammatory breast cancer.