Melatonin controls cell proliferation and modulates mitochondrial physiology in pancreatic stellate cells

Journal of Physiology and Biochemistry - We have investigated the effects of melatonin on major pathways related with cellular proliferation and energetic metabolism in pancreatic stellate cells....     

Nupr1 deficiency downregulates HtrA1, enhances SMAD1 signaling,and suppresses age-related bone loss in male mice

Nuclear protein 1 (NUPR1) is a stress-induced protein activated by various stresses, such as inflammation and oxidative stress. We previously reported that Nupr1 deficiency increased bone volume by enhancing bone formation in 11-week-old mice. Analysis of differentially expressed genes between wild-type (WT) and Nupr1-knockout (Nupr1-KO) osteocytes revealed that high temperature requirement A 1 (HTRA1), a serine protease implicated in osteogenesis and transforming growth factor-β signaling was markedly downregulated in Nupr1-KO osteocytes. Nupr1 deficiency also markedly reduced HtrA1 expression, but enhanced SMAD1 signaling in in vitro-cultured primary osteoblasts. In contrast, Nupr1 overexpression enhanced HtrA1 expression in osteoblasts, suggesting that Nupr1 regulates HtrA1 expression, thereby suppressing osteoblastogenesis. Since HtrA1 is also involved in cellular senescence and age-related diseases, we analyzed aging-related bone loss in Nupr1-KO mice. Significant spine trabecular bone loss was noted in WT male and female mice during 6−19 months of age, whereas aging-related trabecular bone loss was attenuated, especially in Nupr1-KO male mice. Moreover, cellular senescence-related markers were upregulated in the osteocytes of 6−19-month-old WT male mice but markedly downregulated in the osteocytes of 19-month-old Nupr1-KO male mice. Oxidative stress-induced cellular senescence stimulated Nupr1 and HtrA1 expression in in vitro-cultured primary osteoblasts, and Nupr1 overexpression enhanced p16^ink4a expression in osteoblasts. Finally, NUPR1 expression in osteocytes isolated from the bones of patients with osteoarthritis was correlated with age. Collectively, these results indicate that Nupr1 regulates HtrA1-mediated osteoblast differentiation and senescence. Our findings unveil a novel Nupr1/HtrA1 axis, which may play pivotal roles in bone formation and age-related bone loss.     

p8 gene is necessary for tumor establishment

We identified a new gene, called p8, which showed a strong induction during the acute phase of pancreatitis. Further experiments have shown that p8 mRNA is activated in response to several stresses and that its activation is not restricted to pancreatic cells. p8 is a nuclear protein and biochemical and biophysical studies showed that p8 was in many structural aspects very similar to the HMG (high mobility group) proteins, although sharing with them low amino acid sequence homology. Also, p8 was found overexpressed in many human cancers. Therefore, we wondered whether the p8-mediated response to cellular stress was necessary for tumor establishment. Subcutaneous or intraperitoneal injections of transformed p8-expressing fibroblasts led to tumor formation in nude mice, but no tumor was observed with transformed p8-deficient cells. Restoring p8 expression in transformed p8-deficient fibroblasts led to tumor formation demonstrating that p8 expression is necessary for tumor development and suggesting that the stress-response mechanisms governed by p8 are required for tumor establishment.     

A novel arylethynyltriazole acyclonucleoside inhibits proliferation of drug-resistant pancreatic cancer cells

Novel arylethynyltriazole acyclonucleosides were synthesized and assessed for their anticancer activity on drug-resistant pancreatic cancer MiaPaCa-2 cells. One lead compound was found to have much more potent apoptosis-related antiproliferative effects than gemcitabine, the current first-line treatment for pancreatic cancer. Further investigations showed that this active compound did not inhibit DNA synthesis, which means that it does not resemble gemcitabine and may involve a different mechanism of action.     

Cloning of IP15, a pancreatitis-induced gene whose expression inhibits cell growth

We describe the cloning and expression of the mouse gene interferon-inducible-protein 15 (IP15), whose activation is related to the acute phase of experimental pancreatitis. Analysis of its structure indicates that it encodes a putative transmembrane protein of 137 amino acids. This gene contains a predicted IFN-stimulable-response element. In vivo studies showed that IP15 is strongly activated in pancreas early during caerulein-induced pancreatitis. In situ hybridization of IP15 mRNA showed that its expression is restricted to acinar cells. IP15 was also induced in pancreas under systemic-lipopolysaccharide treatment and in intestine under Salmonella infection. In vitro studies using NIH3T3 fibroblasts showed that IP15 is induced by IFN-alpha. Growth rate was significantly lower in cells transfected with pcDNA4/IP15 plasmid. In addition, cells expressing IP15 showed less capacity to develop colonies after antibiotic selection. In conclusion, we identified a new interferon-inducible gene that is activated early in pancreas with pancreatitis and whose expression inhibits cell growth.     

Tie1 deficiency induces endothelial-mesenchymal transition

Endothelial-mesenchymal transition (EndMT) has a significant role in embryonic heart formation and in various pathologies. However, the molecular mechanisms that regulate EndMT induction remain to be elucidated. We show that suppression of receptor tyrosine kinase Tie1 but not Tie2 induces human endothelial cells to undergo EndMT and that Slug deficiency reverts this process. We find that Erk1/2, Erk5 and Akt cascades control Slug promoter activity induced by Tie1 deficiency. Interestingly, EndMT is present in human pancreatic tumour. We propose that EndMT associated with Tie1 downregulation participates in the pathological development of stroma observed in tumours.