Unique expression pattern of the α6β4 integrin and laminin-5 in human prostate carcinoma

BACKGROUND. The α6β4 integrin and its ligand, laminin-5, are essential gene products for the maintenance and remodeling of a stratified epithelium. Apparent loss of polarized α6β4 integrin and laminin-5 protein expression in invasive prostate cancer as compared to normal prostate glands is known to occur. It is unknown whether these alterations occur in prostatic intraepithelial neoplasia (PIN) lesions and whether this combined defect occurs in other epithelial cancers. METHODS. Human prostate tissues containing both normal, PIN, and cancerous regions and normal and cancer tissue from breast and colon were obtained at surgery and examined for β4 integrin and laminin-5 using standard immunofluorescence staining methods. RESULTS. Both normal prostate glands and PIN lesions contain β4 integrin and laminin-5. Prostate carcinoma was unique in that both β4 integrin and laminin-5 expression was uniformly absent. In contrast, the β4 integrin and its ligand, laminin-5 were detected in all of the colon carcinoma cases and in 60% of the breast carcinomas. CONCLUSIONS. The β4 integrin and its ligand, laminin-5 are altered during the transition of PIN lesions to invasive prostate carcinoma. These data suggest the loss of these proteins during cancer progression. In both prostate and breast carcinoma, the normal expression pattern of the β4 integrin and laminin-5 is interrupted, in contrast to the persistent β4 integrin and laminin-5 expression detected in colon carcinoma.