Abstract
Protein expression levels in immunohistochemistry and molecular biomarkers have been reported for their ability to predict recurrence, progression, development of metastases, and patient survival. The molecular features in low- and high-grade prostate cancer can differ and influence treatment decision and prognosis. The objective of the current study was to compare the expression of exosomal biomarkers CD63 and mismatch repair proteins (MSH2, MSH6, MLH1, and PMS2) by immunohistochemistry (IHC) in tissue of patients with prostate cancer and benign hyperplasia. Altogether, 62 patients with prostate acinar adenocarcinoma and 20 patients with prostate benign hyperplasia were enrolled in this retrospective study. CD63, MSH2, MSH6, MLH1, and PMS2 expression was analysed by immunohistochemistry. The obtained results showed that CD63 expression was significantly higher in patients with Grade III–V prostate cancer compared to Grade I–II, respectively; 2.23 (1–3) vs 0.92 (0–2) score, p = 0.001. In addition, a significant positive correlation between CD63 expression and grade groups was revealed (Rho = +0.54; p < 0.0001). Furthermore, progression-free survival was significantly higher in patients with low CD63 expression, compared to high CD63 expression (p = 0.0007). MMR expression was absent in 14 patients (four patients with Grade I–II cancer and 10 patients with Grade III–cancer). MMR was present in all cases of benign prostate hyperplasia (mild to moderate staining). The conclusion was that high grade prostate cancer (Grade groups III–V) was characterised by increased CD63 expression, which correlated with progression-free survival.