Caveolin-1 in Breast Cancer: Single Molecule Regulation of Multiple Key Signaling Pathways

Caveolin-1 is a 22-kD trans-membrane protein enriched in particular plasma membrane invaginations knownas caveolae. Cav-1 expression is often dysregulated in human breast cancers, being commonly upregulated incancer cells and downregulated in stromal cells. As an intracellular scaffolding protein, Cav-1, is involved inseveral vital biological regulations including endocytosis, transcytosis, vesicular transport, and signaling pathways.Several pathways are modulated by Cav-1 including estrogen receptor, EGFR, Her2/neu, TGFβ, and mTOR andrepresent as major drivers in mammary carcinogenesis. Expression and role of Cav-1 in breast carcinogenesisis highly variable depending on the stage of tumor development as well as context of the cell. However, recentdata have shown that downregulation of Cav-1 expression in stromal breast tumors is associated with frequentrelapse, resistance to therapy, and poor outcome. Modification of Cav-1 expression for translational cancertherapy is particularly challenging since numerous signaling pathways might be affected. This review focuses onpresent understanding of Cav-1 in breast carcinogenesis and its potential role as a new biomarker for predictingtherapeutic response and prognosis as well as new target for therapeutic manipulation.