Recombinant Human Prolidase (rhPEPD) Induces Wound Healing in Experimental Model of Inflammation through Activation of EGFR Signalling in Fibroblasts

Serum prolidase activity, oxidative stress, and antioxidant enzyme levels in patients with prostate cancer

OBJECTIVES

We aimed to identify serum prolidase activity, oxidative stress, and antioxidant enzyme levels in patients with prostate cancers and to evaluate their relationships with each other.

MATERIALS AND METHODS

A total of 34 male patients with prostate cancer and with a mean age of 64.2 ± 4.4 were included in the study. The control group comprising 36 male patients (mean age 61.2 ± 3.4) was randomly selected among the volunteers. Serum samples for measurement of superoxide dismutase (SOD), glutathione peroxidase (GPx), Catalase (CAT), malondialdehyde (MDA), glutathione (GSH), and prolidase levels were kept at -20°C until they were used.

RESULTS

Serum prolidase activity and MDA levels were significantly higher in prostate cancer patients than in controls (all, P < 0.05), while SOD, GPx, and CAT levels were significantly lower (P < 0.05).

CONCLUSION

Our results indicate that increased prolidase seems to be related to increased oxidative stress along with decreased antioxidant levels in prostate cancer.

KLF6 activates Sp1-mediated prolidase transcription during TGF-β1 signaling

Prolidase (PEPD) is the only hydrolase that cleaves the dipeptides containing C-terminal proline or hydroxyproline-the rate-limiting step in collagen biosynthesis. However, the molecular regulation of prolidase expression remains largely unknown. In this study, we have identified overlapping binding sites for the transcription factors Krüppel-like factor 6 (KLF6) and Specificity protein 1 (Sp1) in the PEPD promoter and demonstrate that KLF6/Sp1 transcriptionally regulate prolidase expression. By cloning the PEPD promoter into a luciferase reporter and through site-directed deletion, we pinpointed the minimal sequences required for KLF6 and Sp1-mediated PEPD promoter-driven transcription. Interestingly, Sp1 inhibition abrogated KLF6-mediated PEPD promoter activity, suggesting that Sp1 is required for the basal expression of prolidase. We further studied the regulation of PEPD by KLF6 and Sp1 during transforming growth factor β1 (TGF-β1) signaling, since both KLF6 and Sp1 are key players in TGF-β1 mediated collagen biosynthesis. Mouse and human fibroblasts exposed to TGF-β1 resulted in the induction of PEPD transcription and prolidase expression. Inhibition of TGF-β1 signaling abrogated PEPD promoter-driven transcriptional activity of KLF6 and Sp1. Knock-down of KLF6 as well as Sp1 inhibition also reduced prolidase expression. Chromatin immunoprecipitation assay supported direct binding of KLF6 and Sp1 to the PEPD promoter and this binding was enriched by TGF-β1 treatment. Finally, immunofluorescence studies showed that KLF6 co-operates with Sp1 in the nucleus to activate prolidase expression and enhance collagen biosynthesis. Collectively, our results identify functional elements of the PEPD promoter for KLF6 and Sp1-mediated transcriptional activation and describe the molecular mechanism of prolidase expression.