The distribution of alpha6/
alpha3 integrin in adhesion complexes at the basal membrane in human normal and
cancer prostate glands was analyzed in 135 biopsies from 61 patients. The levels of the polarized alpha6/
alpha3 integrin expression at the basal membrane of prostate
tumor glands were determined by quantitative immunohistochemistry. The alpha6/
alpha3 integrin expression was compared with Gleason sum score, pathological stage, and preoperative serum
prostate-specific antigen (PSA). The associations were assessed by statistical methods. Eighty percent of the
tumors expressed the alpha6 or
alpha3 integrin and 20% was
integrin-negative. Gleason sum score, but not serum PSA, was associated with the
integrin expression. Low Gleason sum score correlated with increased
integrin expression, high Gleason sum score with low and negative
integrin expression. Three prostate
tumor phenotypes were distinguished based on differential
integrin expression. Type I coexpressed both alpha6 and alpha3 subunits, type II exclusively expressed
alpha6 integrin, and type III expressed
alpha3 integrin only. Fifteen cases were further examined for the codistribution of
vinculin,
paxillin, and CD 151 on frozen serial sections using confocal
laser scanning microscopy. The alpha6/alpha3
integrins, CD151,
paxillin, and
vinculin were present within normal glands. In prostate
carcinoma,
alpha6 integrin was colocalized with CD 151, but not with
vinculin or
paxillin. In
tumor phenotype I, the alpha6 subunit did not colocalize with the alpha subunit indicating the existence of two different adhesion complexes. Human prostate
tumors display on their cell surface the alpha6beta1 and/or alpha3beta1
integrins. Three
tumor phenotypes associated with two different adhesion complexes were identified, suggesting a reorganization of cell adhesion structures in
prostate cancer.