The Cx43-Mediated Autophagy Mechanism Influences Triple-Negative Breast Cancer Through the Regulation of Rab31

Background: Connexin43 (Cx43) is recognized as a transmembrane protein; its precise expression profile and molecular mechanisms in triple-negative breast cancer (TNBC) remain unclear. Methods: We systematically analyzed Cx43 expression in over 60 breast cancer cell lines from the CCLE and HPA databases. Immunohistochemical evaluation compared Cx43 expression between TNBC tissues and adjacent normal tissues. Cx43 expression was assessed in normal breast epithelial cells (MCF-10A) and two TNBC cell lines (MDA-MB-231 and BT-549) using qRT-PCR and Western blot. Functional assays (CCK8, wound healing, transwell) evaluated TNBC progression following Cx43 interference or overexpression. Rab31, a Cx43-interacting protein, was identified via bioinformatics, immunofluorescence, and Co-IP. Autophagy-related proteins (ULK1, ATG5, LC3, and p62) were analyzed after Cx43 or Rab31 modulation. Finally, a nude mouse model validated Cx43's in vivo effects on tumor growth and associated molecular changes. Results: Cx43 was upregulated in TNBC tissues and cell lines. Overexpression enhanced proliferation, migration, and invasion, while knockdown suppressed these effects. Cx43 co-expressed with Rab31, regulating its protein levels and autophagy. Rab31 interference reversed Cx43-mediated autophagy and oncogenic behaviors. In vivo, Cx43 promoted tumor growth and modulated Rab31/autophagy pathways. Conclusions: The Cx43/Rab31 axis drives autophagy to facilitate TNBC progression, highlighting Cx43 as a potential therapeutic target. Our findings provide mechanistic insights for improving TNBC treatment.