Prognostic value of alpha 6 beta 4 integrin expression in breast carcinomas is affected by laminin production from tumor cells.

Immunocytochemical analysis of breast carcinoma specimens for alpha 6 beta 4 integrin expression and other different pathobiological markers revealed beta 4 integrin subunit expression in 36 of 80 cases analyzed and a significant association only with alpha 6 integrin subunit expression (P < 0.01) and laminin production (P = 0.01) by tumor cells. Survival analysis indicated that beta 4 and alpha 6 expression are associated with poor prognosis (P = 0.02), whereas laminin production showed only borderline association (P = 0.06). However, analysis of disease outcome in relation to expression of both alpha 6 beta 4 and laminin indicated best outcomes for patients with tumors producing laminin but not expressing alpha 6 beta 4 integrin, whereas worst outcomes were observed for alpha 6 beta 4- and laminin-positive tumors, indicating that alpha 6 beta 4 expression was associated with prognosis, mainly in the laminin-producing tumor subset. These data indicate that the prognostic value of alpha 6 beta 4 integrin expression is affected by laminin production from tumor cells and suggest that interaction between these two molecules mediates distinct signals that are important for tumor progression.