Acetylsalicylic acid prevents nickel-induced collagen biosynthesis in human fibroblasts

Targeting prolidase. A survey of the literature data to depict a structure-activity relationship frame and to address future studies for drug development

Prolidase (EC.3.4.13.9) is a Mn+2-dependent dipeptidase that is well known to play a crucial role in several physiological and pathological processes affecting humans. More in particular, this enzyme is involved in the cleavage of proline- and hydroxyproline-containing dipeptides (imidodipeptides), providing a fine regulation of the homeostasis of these two amino acids. Hyperactivity or deficiency of prolidase have been clearly associated to the development and progress of several acute and chronic syndromes (e.g. chronic liver fibrosis, viral and acute hepatitis, cancer, neurological disorders, inflammation, skin diseases, intellectual disability, respiratory infection). Thus, targeting prolidase and modulating its activity is an intriguing field of research with a great therapeutic potential for the next future and for the design of specific and selective drugs. Prolidase can be exploited in two essential ways: as an activator of proline containing prodrugs and by direct interaction. In this latter case, few specific ligands for the title enzyme have been described, but with no reports about their structure-activity relationship. The aim of this comprehensive review is to gather all available information on prolidase targeting so far reported in the literature, to rationalize the observed data and effect into a preliminary structure-relationship picture, to comment about the effectiveness of each reported ligands, and to address future research activities providing new potential and putative natural, semisynthetic, and purely synthetic molecules able to trigger prolidase as the main biological target.

Nickel oxide nanoparticles induced pulmonary fibrosis via TGF-β1 activation in rats

Nano nickel oxide (NiO), widely used in industry, has recently been discovered to have pulmonary toxicity. However, no subchronic exposure studies about nano NiO-induced pulmonary fibrosis have been reported. The objective of this study was to investigate pulmonary fibrosis induced by nano NiO and its potential mechanism in rats. Male Wistar rats ( n = 40, 200–240 g) were randomized into control group, nano NiO groups (0.015, 0.06, and 0.24 mg/kg), and micro NiO group (0.024 mg/kg). All rats were killed to collect lung tissue after intratracheal instillation of NiO particles twice a week for 6 weeks. To identify pulmonary fibrosis, Masson trichrome staining, hydroxyproline content, and collagen protein expression were performed. The results showed widespread lung fibrotic injury in histological examination and increased content of hydroxyproline, collagen types I and III in rat lung tissue exposed to nano NiO. To explore the potential pulmonary fibrosis mechanism, transforming growth factor beta 1 (TGF- β1) content was measured by enzyme-linked immunosorbent assay, and the messenger RNA expression of key indicators was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The TGF- β1 content was increased in nano NiO exposure groups, as well as the upregulated gene expression of TGF- β1, Smad2, Smad4, matrix metalloproteinase, and tissue inhibitor of metalloproteinase. The findings indicated that nano NiO could induce pulmonary fibrosis, which may be related to TGF- β1 activation.

Aspirin counteracts cancer stem cell features, desmoplasia and gemcitabine resistance in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is characterized by an extremely poor prognosis. An inflammatory microenvironment triggers the pronounced desmoplasia, the selection of cancer stem-like cells (CSCs) and therapy resistance. The anti-inflammatory drug aspirin is suggested to lower the risk for PDA and to improve the treatment, although available results are conflicting and the effect of aspirin to CSC characteristics and desmoplasia in PDA has not yet been investigated. We characterized the influence of aspirin on CSC features, stromal reactions and gemcitabine resistance. Four established and 3 primary PDA cell lines, non-malignant cells, 3 patient tumor-derived CSC-enriched spheroidal cultures and tissues from patients who did or did not receive aspirin before surgery were analyzed using MTT assays, flow cytometry, colony and spheroid formation assays, Western blot analysis, antibody protein arrays, electrophoretic mobility shift assays (EMSAs), immunohistochemistry and in vivo xenotransplantation. Aspirin significantly induced apoptosis and reduced the viability, self-renewal potential, and expression of proteins involved in inflammation and stem cell signaling. Aspirin also reduced the growth and invasion of tumors in vivo, and it significantly prolonged the survival of mice with orthotopic pancreatic xenografts in combination with gemcitabine. This was associated with a decreased expression of markers for progression, inflammation and desmoplasia. These findings were confirmed in tissue samples obtained from patients who had or had not taken aspirin before surgery. Importantly, aspirin sensitized cells that were resistant to gemcitabine and thereby enhanced the therapeutic efficacy. Aspirin showed no obvious toxic effects on normal cells, chick embryos or mice. These results highlight aspirin as an effective, inexpensive and well-tolerated co-treatment to target inflammation, desmoplasia and CSC features PDA.

Effect of mercury, cadmium, nickel, chromium and zinc on kinetic properties of NADPH-cytochrome P450 reductase purified from leaping mullet (Liza saliens)

Information on the mechanism of metal ion inhibition of NADPH-cytochrome P450 reductase is limited. The purpose of the present paper was to elucidate in vitro effect of Hg(+2), Cd(+2), Ni(+2), Cr(+3) and Zn(+2) ions on the purified mullet NADPH-cytochrome P450 reductase. NADPH-cytochrome P450 reductase was purified from detergent-solubilized liver microsomes from leaping mullet (Liza saliens). All of the metal ions caused inhibition of the enzyme activity except Zn(+2). At 50 microM metal concentration, Hg(+2) inhibited the cytochrome P450 reductase activity completely (100%), while, at the same concentrations, Cd(+2), Cr(+3) and Ni(+2) caused 66%, 65% and 37% inhibition, respectively. At 50 microM metal concentration, Zn(+2) had no apparent effect on cytochrome P450 reductase activity. The IC(50) values of HgCl(2), CrCl(3), CdCl(2) and NiCl(2) were estimated to be 0.07 microM, 24 microM, 33 microM and 143 microM, respectively. Of the metal ions tested, Hg(+2) exhibited much higher inhibitory effect at lower concentrations, so it was evidently a more potent inhibitor than the others. All four metal ions displayed noncompetitive type of inhibition mechanism for the purified reductase as analyzed by Dixon plot. K(i) values of Hg(+2), Cr(+3), Cd(+2), and Ni(+2) were calculated from Dixon plots as 0.048 microM, 18 microM, 73 microM and 329 microM, respectively.