HSD17B4 overexpression, an independent biomarker of poor patient outcome in prostate cancer

Steroid hormones and their metabolising enzymes have been studied extensively for their potential role in prostate cancer, with more recent interest in the androgen/estrogen inactivating enzyme 17β-hydroxysteroid dehydrogenase type 4 (HSD17B4). Gene expression profiling showed HSD17B4 to be significantly overexpressed in prostate cancer compared to matched-benign epithelium. We therefore hypothesized that altered HSD17B4 expression may contribute to prostate cancer progression via altered hormone balance. In this study, HSD17B4 mRNA and protein expression were assessed by in situ hybridisation (ISH) and immunohistochemistry (IHC), respectively, in tissue arrays of prostate tissue from 172 patients treated by radical prostatectomy. Overexpression of HSD17B4 mRNA and protein was associated with prostate cancer (P < 0.0001) and multivariate Cox proportional hazards analysis, adjusted for known prognostic indicators, demonstrated HSD17B4 mRNA and high protein expression were significant independent predictors of poor patient outcome as measured by time until PSA relapse (mRNA: hazards ratio [HR] = 1.90, 95% confidence interval [CI] = 1.15–3.12; P < 0.0001; and protein: HR = 2.09, 95% CI = 1.31–3.33; P = 0.0026). Here we provide strong evidence that both mRNA and protein overexpression of HSD17B4 is not only associated with the presence of prostate cancer, but is also a significant independent predictor of poor patient outcome.