Regulation of prostate cell collagen receptors by malignant transformation

Cell adhesion receptors, including the integrin-type collagen receptors (α1β1, α2β1, α10β1 and α11β1) 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 α1β1 and α2β1 only. This was surprising because α11β1 has been connected previously to the progression of lung adenocarcinomas. To test the hypothesis that α11 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 α11 mRNA levels. In prostate α2 expression was significantly lower in poorly differentiated carcinomas when compared to benign lesions (p = 0.0331). In immunohistochemistry the protein levels of α2 integrin decreased significantly (p = 0.0001) and the protein levels of α11 subunit increased significantly (p = 0.029) with the increasing grade of carcinoma. Thus α11β1 may replace α2β1 during tumor progression. Our observations support the idea that α11β1 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 α2β1 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 α2β1 and AR. Androgen receptors may control the mechanisms regulating integrin expression in prostate. © 2005 Wiley-Liss, Inc.