Osteonectin overexpression in the case of prostate cancer with intraluminal inclusions

Abstract

Osteonectin (OSN) is secreted by osteoblasts during bone formation, initiating mineralization and promoting mineral crystal formation at sites of ectopic calcification. Also OSN was found in many types of human malignant tumours. The aim is to study the OSN expression in patients with prostate cancer (PC) and the presence of intraluminal inclusions (prostatolithes and amyloid cells). Method: OSN expression was investigated in tumours and in the adjacent prostatic tissue of 30 PCs with intraluminal inclusions and 30 PCs without them by immunohistochemistry. In each group 15 samples refer to moderately differentiated G2 and low-differentiated G3 tumours. Samples were fixed, embedded in paraffin, and analized for OSN accumulation using the anti-OSN antibody, followed by DAB detection substrate and counterstained with Mayer’s haematoxylin. Results: OSN expression was increased in PC tissues with pathological inclusions in comparison to those without them (p<0.001, Student test). Osteonectin was mostly localized in tumour cells cytoplasm, its expression was not observed in tumour microangiourea cells and in stroma. It was found that the OSN expression by tumour cells reduced during reduction of the malignant tumour differentiation (comparison of subgroups G2 and G3) (p<0.001 and p<0.01 respectively for groups I and II). Conclusion: OSN overexpression in tumours and in the adjacent prostatic tissue of PCs with intraluminal inclusions may be regarded as a prospective role for the osteosteogenic phenotype development of tumour cells and for the bone metastasis promotion.