Decreased RECK Expression Indicating Proteolytic Imbalance in Prostate Cancer is Associated with Higher Tumor Aggressiveness and Risk of Prostate-Specific Antigen Relapse after Radical Prostatectomy

Abstract

Objectives

Decreased expression of reversion-inducing cysteine-rich protein with Kazal motifs (RECK) was recently shown in several cancer types. To evaluate its potential role for prostate carcinoma, we investigated RECK expression in prostate cancer (pCA) samples.

Methods

RECK messenger RNA levels in 15 microdissected normal/tumor matches were determined by quantitative reverse transcriptase-polymerase chain reaction. Protein expression of RECK was evaluated by immunohistochemical staining in tissue samples of adenomectomies (n = 24) and pCA samples after radical prostatectomy (n = 247). RECK expression was related to preoperative prostate-specific antigen (PSA), tumor stage and grade, surgical margin status, and PSA relapse-free time after radical prostatectomy.

Results

Consistent with lower RECK messenger RNA by 24%, RECK protein expression was decreased in pCA, compared with adjacent normal tissue and prostatic intraepithelial neoplasia. RECK expression in samples of benign prostatic hyperplasia from adenomectomy specimens was higher than in normal adjacent tissue of prostate carcinomas. Decreased RECK expression was associated with higher Gleason score (≥7) and higher tumor stage. Multivariate analysis using the Cox proportional hazards model revealed that negative RECK expression was an independent prognostic factor for an increased risk of PSA relapse, especially in patients with higher tumor grades (Gleason score ≥7).

Conclusions

Decreased RECK expression correlating with the aggressiveness of pCA and the PSA relapse-free time could become an adjunct tissue biomarker to improve the follow-up and treatment decision for these pCA patients.

Introduction

Despite current improvements in diagnosis and therapy of prostate cancer (pCA), there are problems of overtreatment based on the absence of indicators to accurately predict the aggressiveness of pCA. The conventional prognostic markers like tumor stage, tumor grade, and preoperative prostate-specific antigen (PSA) show limited accuracy to predict the clinical outcome [1], [2]. Thus, the search for novel biomarkers that are capable of discriminating between pCA with low and high aggressiveness and recurrence potential is a compelling task to provide the opportunity of custom-made therapy. Tissue invasion and metastasis are essential alterations that occur in malignancy [3]. A dysbalance of matrix metalloproteinases (MMPs), promoting tumor invasion and metastasis, to their inhibitors is characteristic for pCA [4], [5], [6] and opens the possibility of counteracting MMPs with synthetic inhibitors [7], [8]. Consequently, we directed our efforts to the new endogenous MMP inhibitor RECK (reversion-inducing-cysteine-rich protein with Kazal motifs), an inhibitor of MMP-2, MMP-9, and MT1-MMP.

RECK was originally found to suppress transformation in v-Ki-ras-transformed NIH3T3 fibroblasts. The glycoprotein RECK has serine protease inhibitor-like domains and a C-terminal tail of glycophosphatidylinositol anchoring the protein extracellularly to the cell membrane where it inhibits MMPs [9]. RECK −/− mouse embryos die with severe vascular disorders [10]. This finding agrees with the suppressive function of RECK on tumor angiogenesis and metastasis [9], [10]. RECK messenger RNA (mRNA) is expressed in different human organs and normal cell lines, but was not detected in several tumor cell lines [9]. Recent studies imply a predictive role for RECK in tumorigenesis. Its transcriptional level in human hepatocellular carcinomas correlated positively with the survival time of the patients and negatively with tumor invasion [11]. Similar results were shown in pancreatic adenocarcinomas [12]. Mammary carcinomas revealed decreased expression of RECK mRNA in comparison with normal breast tissue [13]. Patients with higher RECK expression showed a prolonged recurrence-free survival time. Likewise, immunohistochemical experiments on lung cancer and colorectal carcinomas suggested a prognostic role for RECK, because enhanced RECK expression correlated with less tumor angiogenesis and a better postoperative prognosis [14], [15], [16]. In colorectal cancer, RECK mRNA expression was negatively correlated to MMP-2 and positively associated with overall survival [17].

In view of these results and the rare data for RECK expression in pCA [18], we evaluated the significance of RECK in pCA. Our aim was to determine the expression of RECK at the transcriptional and translational levels, and to clarify the relationship of RECK expression with clinicopatholologic parameters of pCA to evaluate the validity of RECK as a diagnostic or prognostic marker.