Contributions of the alpha6 integrins to breast carcinoma survival and progression.

This review summarizes recent findings that support a key role for the alpha6 integrins (alpha6beta1 and alpha6beta4) in the progression of breast carcinoma. The hypothesis that emerges from the existing data is that both of these integrins have the ability to sustain the survival of breast carcinoma cells, especially in stress conditions such as those that exist in the tumor microenvironment. The mechanisms by which these integrins promote survival appear to involve their ability to regulate the expression of vascular endothelial growth factor (VEGF), either at the level of transcription or translation. VEGF produced by breast carcinoma cells in response to alpha6 integrin regulation can function in an autocrine manner to promote survival signaling.