Regulation of prostate cell collagen receptors by malignant transformation

Cell adhesion receptors, including the integrin‐type collagen receptors (α 1 β 1 , α 2 β 1 , α 10 β 1 and α 11 β 1 ) participate in cancer progression and invasion. Quantitative RT‐PCR indicated that all 4 receptors are abundantly expressed in sarcoma‐derived cell lines, whereas most carcinoma‐derived cells express α 1 β 1 and α 2 β 1 only. This was surprising because α 11 β 1 has been connected previously to the progression of lung adenocarcinomas. To test the hypothesis that α 11 expression may not persist in cultured cancer cells we analyzed fresh tissue samples of 104 total prostatectomies, keeping in mind that prostate cancer cell lines showed negligible α 11 mRNA levels. In prostate α 2 expression was significantly lower in poorly differentiated carcinomas when compared to benign lesions ( p = 0.0331). In immunohistochemistry the protein levels of α 2 integrin decreased significantly ( p = 0.0001) and the protein levels of α 11 subunit increased significantly ( p = 0.029) with the increasing grade of carcinoma. Thus α 11 β 1 may replace α 2 β 1 during tumor progression. Our observations support the idea that α 11 β 1 may be expressed in tumors but the corresponding cell lines may lose the expression of this integrin. Previous studies have shown that in cell culture androgen receptor (AR) controls α 2 β 1 expression. We measured AR mRNA levels and the number of AR positive nuclei in the prostate samples and the results showed a significant correlation between α 2 β 1 and AR. Androgen receptors may control the mechanisms regulating integrin expression in prostate. © 2005 Wiley‐Liss, Inc.