277 Background: Protein tyrosine phosphorylation is an important event that is associated with the processes of cellular metabolism. The control of protein tyrosine phosphorylation is regulated by protein tyrosine kinases and protein tyrosine phosphatases (PTP). Thus, these proteins can control diverse processes like cell proliferation, adhesion, and migration. Recent studies revealed the importance of PTP in the oncogenic process, especially, the significance of low-molecular-weight protein tyrosine phosphatase (LMW-PTP) as a prognostic factor in early prostate cancer. In this study, we evaluated the significance of expression of LMW-PTP in metastatic hormone-sensitive prostate cancer (mHSPC) as a prognostic biomarker. Methods: We identified consecutive 48 men with mHSPC. The prostate cancer tissues obtained by needle biopsies were immunohistochemically stained for LMW-PTP. A pathologist blindly evaluated the expression of LMW-PTP and intensity of staining was classified into two groups, high (diffusely strongly positive) and low (at least focally weak-negative). The correlations between clinicopathological characteristics including age, initial PSA levels, Gleason scores, T stage, N stage, extend of disease on bone scan (EOD), and expression of LMW-PTP and overall survival (OS) were analyzed by multivariate analysis using cox proportional hazards regression model. Results: Median age was 70.0 years and median initial PSA level was 85.4 ng/mL. Gleason scores were 6-7 in 16 patients (33.4%) and 8-10 in 32 patients (66.6%). Clinical T stages were T2-3 disease in 34 patients (70.8%) and T4 in 14 patients (29.2%). Clinical N stages were N0 disease in 21 patients (43.7%) and N1 in 27 patients (56.3%). EOD grades were 0 in 13 patients (27.0%), 1 in 12 patients (25.0%), 2 in 14 patients (29.2%), 3 in 8 patients (16.7%), and 4 in 1 patient (2.1%). Multivariate analysis revealed that Gleason score (≥ 8 vs ≤ 7; HR: 5.795, 95%CI: 1.266-26.520, p = 0.024) and LMW-PTP expression (high vs low; HR: 2.736, 95%CI: 1.035-7.232, p = 0.042) were independent prognostic factors for OS. Conclusions: LMW-PTP might be a potential biomarker to predict overall survival for men with mHSPC.
Low-molecular-weight Protein Tyrosine Phosphatase Is a Possible Biomarker for Predicting Postoperative Biochemical Recurrence in Prostate Cancer With Negative Surgical Margins
