Tissue Microarrays Identify Biomarker for Prostate Cancer

Immunohistochemistry has been used to detect the expression of a biomarker for metastatic prostatic adenocarcinomas.

Tissue microarrays made from cores were taken from the appropriate case specific paraffin-embedded tissue blocks were immunohistochemically stained for the protein biomarker claudin-3.

A study performed at University of Pittsburgh School of Medicine, (Pittsburgh, PA, USA), tested microarrays from 17 cases of benign prostatic hyperplasia (BPH), 35 with prostatic intraepithelial neoplasia (PIN), 53 patients with normal tissue adjacent to prostatic adenocarcinoma (NAC), 107 cases with primary prostatic adenocarcinoma (PCa), and 55 cases of metastatic prostatic adenocarcinoma (Mets). The tissue microarrays were stained with a rabbit polyclonal antibody anti-claudin-3 from Thermo Scientific, (Waltham, MA, USA).

In the claudin-3 stained specimens, the average staining scores were highest in PCa and Mets. PIN had a lower absolute staining score than PCa and Mets, although the differences were not significant. Both BPH and NAC had significantly less staining than PCa and Mets. As claudin-3 is a tight junction protein, it is interesting to note that in addition to membranous staining, cytoplasmic staining was also seen in select cores, most prominently in cases of PCa and Mets.

The authors concluded that this study represents one of the first comparing the immunohistochemical profiles of claudin-3 in PCa and NAC to specimens of PIN, BPH, and Mets. These findings provide further evidence that claudin-3 may serve as an important biomarker for prostate cancer, both primary and metastatic, but does not provide evidence that claudin-3 can be used to predict risk of metastasis.

Claudins are integral membrane proteins that are involved in forming cellular tight junctions, and claudin-3, has been shown to be overexpressed in breast, ovarian, and pancreatic cancer. The study was published on January 21, 2011, in Diagnostic Pathology.

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University of Pittsburgh School of Medicine
Thermo Scientific