High RBM3 expression in prostate cancer independently predicts a reduced risk of biochemical recurrence and disease progression

Liv Jonsson,Alexander Gaber,David Ulmert,Karin Jirström,Mathias Uhlén,Anders Bjartell

doi:10.1186/1746-1596-6-91

Abstract

BackgroundHigh expression of the RNA-binding protein RBM3 has previously been found to be associated with good prognosis in breast cancer, ovarian cancer, malignant melanoma and colorectal cancer. The aim of this study was to examine the prognostic impact of immunohistochemical RBM3 expression in prostate cancer.FindingsImmunohistochemical RBM3 expression was examined in a tissue microarray with malignant and benign prostatic specimens from 88 patients treated with radical prostatectomy for localized disease. While rarely expressed in benign prostate gland epithelium, RBM3 was found to be up-regulated in prostate intraepithelial neoplasia and present in various fractions and intensities in invasive prostate cancer. High nuclear RBM3 expression was significantly associated with a prolonged time to biochemical recurrence (BCR) (HR 0.56, 95% CI: 0.34-0.93, p = 0.024) and clinical progression (HR 0.09, 95% CI: 0.01-0.71, p = 0.021). These associations remained significant in multivariate analysis, adjusted for preoperative PSA level in blood, pathological Gleason score and presence or absence of extracapsular extension, seminal vesicle invasion and positive surgical margin (HR 0.41, 95% CI: 0.19-0.89, p = 0.024 for BCR and HR 0.06, 95% CI: 0.01-0.50, p = 0.009 for clinical progression).ConclusionOur results demonstrate that high nuclear expression of RBM3 in prostate cancer is associated with a prolonged time to disease progression and, thus, a potential biomarker of favourable prognosis. The value of RBM3 for prognostication, treatment stratification and follow-up of prostate cancer patients should be further validated in larger studies.

Highlights

High expression of the RNA-binding protein RBM3 has previously been found to be associated with good prognosis in breast cancer, ovarian cancer, malignant melanoma and colorectal cancer
We investigated the prognostic impact of RBM3 expression in prostate cancer by immunohistochemical (IHC) analysis of benign and malignant specimens from 88 patients treated with radical prostatectomy
While absent or weakly expressed in benign prostatic glands (Figure 1A), RBM3 was clearly up-regulated in prostatic intraepithelial neoplasia (PIN) (Figure 1B) and in invasive carcinoma RBM3 was expressed in various fractions and intensities (Figure 1C-E) with 33 (37.5%) cases lacking RBM3 expression (Figure 2)