Expression Levels of MMP9 and PIWIL2 in Prostate Cancer: a Case-Control Study

Prostate cancer is the second most prevalent cancer in humans. Also, this is the most common malignancy and the sixth most important cause of death in men worldwide. The most routine diagnostic test for prostate cancer is PSA test which is associated with some limitations like too many false positive results. This study intends to investigate the role of MMP9 and PIWIL2 expression levels as different biomarkers in prostate cancer biopsy specimens. This study is one of the most brilliant studies in the field of prostate cancer research for the first time focusing on the investigation of the role of two different genes in prostate cancer in biopsy specimens and on formalin-fixed paraffin-embedded tissue types in order to detect the progression and prognosis of prostate cancer patients in early stages.

Seventy formalin-fixed paraffin embedded samples (35 normal and 35 cancerous cases) were selected. Expression levels of PIWIL2 and MMP9 genes were evaluated, using real-time PCR.

MMP9 and PIWIL2 expression levels in cancerous tissues were significantly higher than the adjacent normal tissues (p < 0.05). The survival analysis showed a significant correlation between expression level of PIWIL2 and survival rate (p < 0.05), but such correlation was not observed in case of MMP9 (p > 0.05). Higher levels of MMP9 and PIWIL2 expression were strongly related to the Gleason score and age, using Pearson's correlation co- efficient test; however, this kind of association was not evident between prostate specific antigen (PSA) and expression levels of the genes of interest. The expression level of PIWIL2 had a significant correlation with metastasis rate, but this relationship was not seen in the case of MMP9.

The results confirmed the validity of PIWIL2 expression as a valuable prognostic biomarker for early diagnosis of prostate cancer.