Anti-PCNA Antikörper (A29705)

Prolonged ingestion of a cholesterol-enriched diet induces chronic, auto-inflammatory responses resulting in significant health problems including colorectal cancer. Inflammasomes are thought to mediate intestinal homeostasis, and their dysregulation contributes to inflammatory bowel diseases and colitis-associated cancer (CAC). However, in vitro and in vivo information regarding the inflammation-inducing and tumor-promoting effect of cholesterol is lacking. Here we show that the cholesterol promoted colon carcinogenesis in azoxymethane (AOM)-treated mice through activating the NLRP3 inflammasome. High cholesterol diet (HCD) significantly increased inflammatory responses and tumor burden. Cholesterol crystals, detected in the colon of mice fed with HCD, also promoted NLRP3 inflammasome activation in macrophages, as indicated by elevated expression of cleaved caspase-1, formation of NLRP3-ASC-caspase-1 complex assembly, and higher IL-1β secretion. Importantly, cholesterol was found to inhibit the activity of AMPKα in macrophages, leading to a significant production of mitochondrial ROS, which in turn activated the NLRP3 inflammasome. Moreover, crystal uptake and cathepsin B accounted for cholesterol crystal-induced inactivation of AMPKα. Finally, HCD-induced increase in IL-1β secretion, macrophage infiltration and tumor burden was diminished by the deletion of NLRP3 in AOM-treated mice. Taken together, our findings demonstrate that the pro-inflammatory and cancer-promoting effects of HCD are mediated by the activation of NLRP3 inflammasome. Our study extended our knowledge on how dietary choices can influence processes involved in chronic inflammatory disorders and colorectal cancer.

We investigated potential mechanisms of acute injury in pubertal mice testes after exposure to carbon ion radiation (CIR). Serum testosterone was measured following whole-body irradiation with a 2Gy carbon ion beam. Comparative proteomic profiling and Western blotting were applied to identify potential biomarkers and measure protein expression, and terminal dUTP nick end-labeling (TUNEL) was performed to detect apoptotic cells. Immunohistochemistry and immunofluorescence were used to investigate protein localization. Serum testosterone was lowest at 24h after CIR, and 10 differentially expressed proteins were identified at this time point that included eIF4E, an important regulator of initiation that combines with mTOR and 4EBP1 to control protein synthesis via the mTOR signaling pathway during proliferation and apoptosis. Protein expression and localization studies confirmed their association with acute injury following exposure to CIR. These three proteins may be useful molecular markers for detecting abnormal spermatogenesis following exposure to environmental and therapeutic radiation.

The epidermal growth factor receptor (EGFR) is an important receptor tyrosine kinase member in animals, which plays versatile functions in development, growth, tissue regeneration etc. Current knowledge on EGFR is poor in bivalve mollusks. In this study, we cloned and analyzed an EGFR gene from the Pacific oyster Crassostrea gigas (cgegfr). A 5,731 bp full-length cDNA of cgegfr was obtained, encoding a peptide with 1,494 amino acids which exhibited a typical EGFR structure, including an extracellular region, a single transmembrane region and an intracellular region. A conserved tyrosine kinase domain was predicted in the intracellular region, while the extracellular region responsible for ligand binding showed comparatively poor conservation. Expression analysis revealed that cgefgr was expressed widely in C. gigas tissues and a highest expression level was observed in adductor tissue. Expression of cgegfr was revealed to be up-regulated during wound healing of mantle, indicating that EGFR might function in the cell proliferation and migration during wound healing. Further functional analysis of cgegfr was conducted in mouse myoblast cell line C2C12, in which different parts of cgegfr were expressed and their effects were measured. The results revealed that cgegfr was able to accelerate cell proliferation of C2C12 cells and the transmembrane region was necessary for self-activation of truncated cgegfr. Our results would provide supports for further studies on the roles of cgegfr in development and growth in C. gigas.

Cellular senescence is an irreversible form of cell cycle arrest that provides a barrier to neoplastic transformation. The integrity of the Rb (Retinoblastoma) pathway is necessary for the formation of the senescence-associated heterochromatin foci (SAHF) that offers a molecular basis for the stability of the senescent state. Surprisingly, although high mobility group A2 protein (HMGA2) can promote tumorigenesis and inhibit Rb function in tumor cells, high-level expression of HMGA2 is sufficient to induce SAHF formation in primary cells. It therefore becomes significant to determine whether Rb protein is necessary in HMGA2-induced SAHF formation. In this study, we established the cellular senescence and SAHF assembly WI38 cell model by ectopic expression of HMGA2, in which typical senescent markers were seen, including notable upregulation of p53, p21 and p16, and elevated SA-β-galactosidase staining together with downregulation of E2F target genes. We then showed that the Rb pathway inhibitor E7 protein was able to partly abolish the ability of SAHF formation after HMGA2 expression in WI38 cells, indicating that Rb is a crucial factor for HMGA2-induced SAHF formation. However, Rb depletion did not completely rescue the cell growth arrest induced by HMGA2, suggesting that Rb is not an exclusive pathway for HMGA2-induced senescence in WI38 cells.

Mesenchymal stem cells (MSCs) become a research hotspot in recent years because of their roles in regenerative medicine and tissue injury repair. However, the limited source for MSCs hampers its clinical application. In this study, we isolated and identified human mesenchymal stem cell-like cells from foreskin (hFMSCs) by explant culture. HFMSCs had similar morphology and immunophenotype to that of human bone marrow derived-mesenchymal stem cells. HFMSCs formed colonies after 9 days of inoculation and could be propagated for more than 50 passages. HFMSCs had a normal karyotype and high G0/G1 phase independent of passage number. Further, hFMSCs could be induced to differentiate into osteocytes and adipocytes. We found that the growth of SGC-7901 (human gastric adenocarcinoma) cells could be suppressed by simultaneous injection of hFMSCs in vivo. HFMSCs also inhibited SGC-7901 cell proliferation in vitro. HFMSC co-injection resulted in a decrease in PCNA-positive and an increase in apoptotic tumor cells. HFMSCs derived conditioned medium inhibited the expression of BCL-2 while increased the expression of BAX and caspase-3 in SGC-7901 cells. Taken together, our findings suggest that children foreskin is a new source for MSCs and hFMSCs could inhibit gastric cancer cell growth both in vitro and in vivo.

2,3,4',5-tetrahydroxystilbene-2-0-β-D glucoside (TSG) has been recognized to suppress the proliferation of vascular smooth muscle cells (VSMCs). The aim of the present study was to determine whether TSG inhibits neointimal hyperplasia in a rat carotid arterial balloon injury model. Balloon injury was induced in the left common carotid artery of rats. TSG (30, 60, 120 mg/kg/day) was treated from 3 days prior to, until 14 days after the induction of balloon injury. The ratio of intima-to-media was significantly reduced in the TSG-treated rats at 14 days after the induction of injury, which was associated with reduced expressions of proliferating cell nuclear antigen (PCNA), α-smooth muscle actin (α-SMA) and platelet-derived growth factor-BB (PDGF-BB), as markers of VSMCs proliferation and migration. Additionally, TSG significantly inhibited PDGF-BB induced cell migration in cultured VSMCs. Furthermore, we explored the underlying mechanisms for such effects of TSG. The result showed that TSG markedly reduced balloon injury-induced AKT, extracellular signal-regulated kinase (ERK1/2) and nuclear factor kappaB (NF-κB) activation as well as mRNA expressions of c-myc, c-fos and c-jun, which is important signal pathway for VSMCs proliferation. And in both vivo and vitro model, TSG markedly regulated matrix metalloproteinase-2, 9 expressions and collagen I, III expressions, which are key factors in extracellular matrix for VSMCs migration. These results suggest that the anti-proliferative and anti-migrative effects of TSG on VSMCs could help to explain the beneficial effects of TSG on neointima hyperplasia induced by balloon injury.

PURPOSE:

Oxidative stress plays a central role in heat stress-induced gastrointestinal injury. Punicalagin (PUN), a major polyphenol abundant in pomegranate fruit, husk and juice, exhibits antioxidative effects. In this study we used a heat stress model to investigate the intestinal protection effect of PUN and the underlying mechanisms.

MATERIALS AND METHODS:

IEC-6 cells were pretreated with PUN for 6 h and exposed to 42 °C for 6 h. Intracellular reactive oxygen species levels, malondialdehyde, nitrogen oxide, and superoxide dismutase activity were measured. IEC-6 cells were treated with PUN at different times and doses, the protein levels of haeme oxygenase-1 (HO-1) were evaluated. The nuclear translocation of the transcription factor NF-erythroid 2-related factor (Nrf2) and the phosphorylation level of PI3K/Akt were also investigated.

RESULTS:

PUN significantly decreased the heat stress-induced cell death and apoptosis. Heat stress increased reactive oxygen species, malondialdehyde and nitrogen oxide production, while it decreased superoxide dismutase activity. These effects were markedly inversed when the cells were pretreated with PUN. Furthermore, PUN treatment induced the expression of HO-1 and increased Nrf2 nuclear translocation in a time- and dose-dependent manner. The Nrf2-related cytoprotective effects of PUN were via the PI3K/Akt signalling pathway, as LY294002, a specific PI3K/Akt inhibitor, suppressed the PUN-induced nuclear translocation of Nrf2, the HO-1 up-regulation and the protective effect of PUN against oxidative stress.

CONCLUSIONS:

PUN protects IEC-6 cells against oxidative stress by up-regulating the expression of HO-1 via a mechanism that involves PI3K/Akt activation and Nrf2 translocation.