BackgroundDisturbance in cell cycle regulatory genes is a common finding among many types of cancers. The aim of this study is to evaluate the role of cyclin D1 and DJ-1 in benign prostatic hyperplasia (BPH) and prostate cancer (PC).MethodThe current study enclosed 40 patients diagnosed with PC and 40 cases of BPH. The expression level of cyclin D1 and DJ-1 were evaluated by immunohistochemistry (IHC). Cyclin D1 scored depending on the percentage of stained nuclear tumor cells. While scoring of DJ-1 was based on intensity. The results were correlated with clinicopathological features and outcome.ResultsIn the PC group, cyclin D1 was detected in 95% and overexpressed in 42.5%, DJ-1 was positively stained in 85% and overexpressed in 47.5%. Meanwhile, in the BPH group, cyclin D1 was not detected and DJ-1 stained in only 2.5%. There was a statistically significant difference in Gleason score (GS), tumor stage, size, and treatment failure (p =< 0.001). In the terms of PC diagnosis prediction, although cyclin D1 was more specific (100%), DJ-1 is more sensitive than cyclin D1 (80%, 70%, respectively) (p = 0.000).ConclusionsCyclin D1 and DJ-1 may emerge as a promising way for diagnosis of PC in certain circumstances, as the presence of insufficient tissue sampling, small foci of carcinoma or benign lesions mimic PC. This is in addition to the known role of cyclin D1 and DJ-1 in PC prognosis.