Novel Interactions Between ERα-36 And STAT3 Mediate Breast Cancer Cell Migration

Objective: Breast cancer is the most common malignant tumor in women,and metastasis and recurrence are the leading causes of death in breast cancer patients.Tumor metastasis is a multi-step,multi-stage,multi-path,complex process involving multiple genetic changes.There is increasing evidence that ER-α36 is closely related to STAT3 and tumor metastasis.To explore the new mechanism of ER-α36 and STAT3 interaction mediating breast cancer cell migration,which is of great significance for the prevention and treatment of breast cancer.Methods: The expression plasmids of ER-α36,STAT3,MMP2 and MMP9 were constructed separately,and the vector was pcDNA3.1.The cells were treated with IL-6,and the cells were uniformly expanded to perform scratch test and transwell experiment.The following luciferase reporter plasmids were constructed: WT-MMP2/9-luc containing the complete GAS sequence;M1-MMP2/9-luc containing the mutated GAS sequence;M2-MMP2/9-luc with the GAS sequence truncated;Luciferase reporter gene activity was tested to investigate the effects of ER-α36 and STAT3 on MMP2/9 expression in that manner.Overexpression of ER-α36,STAT3 and co-expression of ER-α36 and STAT3 in two breast cancer cells,using the antibody labeling on the ER-α36 expression plasmid for ChIP experiments,using primers including the MMP2/9 promoter GAS region to detect co-precipitated genes sequence.Western Blot was used to detect the expression of total STAT3 and acetylated phosphorylated STAT3,MMP2,MMP9 and p300 at the protein level,and real-time quantitative fluorescent PCR was used to detect the expression of STAT3,MMP2 and MMP9 at the RNA level.The experiment was performed to detect the localization of MMP2 and MMP9 in cells.Results: According to the above experimental protocol,the following results were obtained: IL-6 induced the expression of MMP2 and MMP9 in breast cancer cells and mediated migration of breast cancer cells;STAT3 mediates IL-6-induced MMP2 and MMP9 expression and breast cancer cell migration;ER-α36 and STAT3 mediate IL-6-induced MMP2 and MMP9 promoter activities;ER-α36 binds to STAT3 and affects STAT3 phosphorylation and acetylation;STAT3 phosphorylation has an effect on IL-6-induced MMP2 and MMP9 expression and breast cancer cell migration;ERα-36 recruits p300 and mediates IL-6-induced STAT3 acetylation;IL-6 effects on nuclearMMP2 and MMP9 translocation;ER-α36 and JAK2-STAT3 signaling pathways cross-regulate human breast cancer cell migration.Conclutions: In this study,we demonstrate that ERα-36 recruits p300 and mediates IL-6-induced STAT3 acetylation.In addition,ERα-36 and STAT3 bind to the MMP2 and MMP9 promoters and mediate MMP2 and MMP9 expression in response to IL-6.MMP2 and MMP9 are transferred from the cytoplasm to the nucleus in response to IL-6.Crosstalk between ERα-36 and STAT3 in human breast cancer cell migration provides a new approach to breast cancer progression.