Prolidase [EC.3.4.13.9] is a cytosolic imidodipeptidase, which specifically splits imidodipeptides with C-terminal proline or hydroxyproline. The enzyme plays an important role in the recycling of proline from imidodipeptides (mostly derived from degradation products of collagen) for resynthesis of collagen and other proline-containing proteins. The enzyme activity is up-regulated by beta(1)-integrin receptor stimulation. The increase in the enzyme activity is due to its phosphorylation on serine/threonine residues. Collagen is not only structural component of extracellular matrix. It has been recognized as a ligand for integrin receptors, which play an important role in signaling that regulate ion transport, lipid metabolism, kinase activation and gene expression. Therefore, changes in the quantity, structure and distribution of collagens in tissues may affect cell signaling, metabolism and function. Several line of evidence suggests that prolidase activity may be a step-limiting factor in the regulation of collagen biosynthesis. It has been shown in different physiologic and pathologic conditions. It is of great importance during wound healing, inflammation, aging, tissue fibrosis and possibly skeletal abnormalities seen in Osteogenesis Imperfecta. The mechanism of prolidase-dependent regulation of collagen biosynthesis was found at both transcriptional and post-transcriptional levels. In this study, we provide evidence for prolidase-dependent transcriptional regulation of collagen biosynthesis. The mechanism was found at the level of NF-kB, known inhibitor of type I collagen gene expression. Modulation of integrin-dependent signaling by stimulatory (i.e. thrombin) or inhibitory (i.e. echistatin) beta(1)-integrin ligands or by nitric oxide donors (i.e. DETA/NO) affect prolidase at post-transcriptional level. All those factors may represent novel approach to pharmacotherapy of connective tissue disorders.

Both preclinical and clinical studies have demonstrated promising results of the role of celecoxib in the treatment and prevention of cancer - the best outcome was observed in colon, breast, prostate and head and neck cancers. However, more clinical trials providing real evidence-based clinical advances of celecoxib use are needed.

Propolis evokes several therapeutic properties, including anticancer activity. These activities are attributed to the action of polyphenols. Previously it has been demonstrated, that one of the most abundant polyphenolic compounds in ethanolic extracts of propolis are chrysin, caffeic acid, p-coumaric acid, and ferulic acid. Although their pro-apoptotic activity on human tongue squamous cell carcinoma cells (CAL-27) was established previously, the detailed mechanism of this process remains unclear. Considering the crucial role of proline metabolism and proline dehydrogenase/proline oxidase (PRODH/POX) in the regulation of cancer cell survival/apoptosis, we studied these processes in polyphenol-treated CAL-27 cells. All studied polyphenols evoked anti-proliferative activity, accompanied by increased PRODH/POX, P53, active caspases-3 and -9 expressions and decreased collagen biosynthesis, prolidase activity and proline concentration in CAL-27 cells. These data suggest that polyphenols of propolis induce PRODH/POX-dependent apoptosis through up-regulation of mitochondrial proline degradation and down-regulation of proline utilization for collagen biosynthesis.

Prolidase [E.C. 3.4.13.9], a member of the matrix metalloproteinase (MMP) family, is a manganese-dependent cytosolic exopeptidase that cleaves imidodipeptides containing C-terminal proline or hydroxyproline. It plays an important role in collagen metabolism, matrix remodeling and cell growth. Nitric oxide (NO), a versatile signaling molecule, regulates many processes including collagen synthesis and matrix remodeling and, thereby, may modulate angiogenesis, tumor invasiveness, and metastasis. Thus, we considered that prolidase may be an important target of NO regulation. In our study, SIN I and DETA/NO were used as NO donors. Both donors increased prolidase activity in a time-dependent and dose-dependent manner. Prolidase activity increased not only with NO donors but also with endogenous NO in cells transfected with iNOS. The effect of iNOS was abolished by treatment with S-methylisothiourea (SMT), a selective inhibitor of iNOS. However, with either exogenous or endogenous sources of NO, the increase in prolidase activity was not accompanied by increased prolidase expression. Therefore, we suspected phosphorylation of prolidase as a potential mechanism regulating enzyme activation. We observed increased serine/threonine phosphorylation on prolidase protein in cells treated with NO donors and in cells transfected with iNOS. To determinate the pathways that may mediate prolidase induction by NO, we first used 8-Br-cGMP, a cGMP agonist, and found that 8-Br-cGMP strongly and rapidly stimulated prolidase activity accompanied by increased phosphorylation. Rp-8-Br-pCPT-cGMP, an inhibitor of cGMP, reduced NO donor-stimulated prolidase activity to control levels. To test whether the MAPK pathway is involved in this NO-dependent activation, we used an ERK1/2 inhibitor and found that it had no effect on prolidase activity increased by NO donors. These results demonstrate that NO stimulates prolidase activity by increasing serine/threonine phosphorylation through PKG-cGMP pathway, but independent of MAPK and suggest an interaction between inflammatory signaling pathways and regulation of the terminal step of matrix degradation.

Objective To profile maternal plasma metabolome in spontaneous preterm birth. Method In this retrospective case-control study, we have examined plasma of patient with preterm birth (between 22 and 36 weeks of pregnancy (n = 57)), with threatened preterm labor (between 23 and 36 weeks of pregnancy (n = 49)), and with term delivery (n = 25). Plasma samples were analysed using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) in positive and negative polarity modes. Results We found 168 differentially expressed metabolites that were significantly distinct between study groups. We determined 51 metabolites using publicly available databases that could be subdivided into one of the five groups: amino acids, fatty acids, lipids, hormones, and bile acids. PLS-DA models, verified by SVM classification accuracy, differentiated preterm birth and term delivery groups. Conclusions Maternal plasma metabolites are different between term and preterm parturitions. Part of them may be related with preterm labor, while others may be affected by gestational age or the beginning of labor. Metabolite profile can classify preterm or term delivery groups raising the potential of metabolome as a biomarker to identify high-risk pregnancies. Metabolomic studies are also a tool to detect individual compounds that may be further tested in targeted researches.