Activation of the PKB/Akt pathway in histological benign prostatic tissue adjacent to the primary malignant lesions

In order to evaluate the molecular heterogeneity of prostate cancer, this study examined the expression of Akt-pathway related parameters within the cancerous prostate gland. PTEN, p-Akt and p27kip1 are known to be altered in prostate cancer. Tissue samples from malignant, tumor adjacent benign and benign areas of 25 whole mounted prostate cancer specimens were processed to 583 tissue microarray cores. Immunohistochemically determined biomarker expression was correlated to the different localizations. p-Akt and p27kip1 showed increased staining in malignant tissue compared to the respective benign tissue (p<0.01 and p<0.05). The adjacent but histologically benign tissue had increased levels (p<0.05 and p<0.01), whereas no significant difference was found between the adjacent and malignant regions. A highly significant correlation of p-Akt and p27kip1 in benign tissue (p<0.001) was lost in the adjacent areas and in the malignant tissue (p=0.054 and p=0.12). In tendency, PTEN expression was decreased in the malignant regions and revealed the highest staining in the adjacent zone. According to the results obtained, the expression of p-Akt and p27kip1 was increased in both the adjacent microscopically benign tissue as well as the primary tumors when compared with the histologically benign tissue specimens that served as biological control. The increased expression of PTEN indicates its regulatory function in the initial steps of a deteriorated cell cycle control as well as uncontrolled cellular proliferation, for example, which seem to be present in the normal prostatic tissue surrounding the primary malignant lesion. The addition of molecular markers to a ‘classical’ histopathological approach might contribute to an enhanced sensitivity of analytical approaches aimed at the detection of malignant or premalignant lesions within prostatic biopsies.