High expression of Met/hepatocyte growth factor receptor suppresses tumorigenicity in NCI-H1264 lung carcinoma cells.

The protein product of c-met proto-oncogene, Met, is a tyrosine kinase receptor for the hepatocyte growth factor (HGF). Met receptor is expressed in normal human bronchial epithelium. In comparison, its expression in squamous cell carcinoma (SQCC) of the lung is markedly decreased in a great majority of cases. To understand further the role of Met receptor overexpression in non-small-cell lung carcinoma, we forced-expressed the full-length met cDNA in the NCI-H1264 (H1264) lung carcinoma cell line with low constitutive expression of this receptor. In vitro studies demonstrated that increased Met expression in H1264 cells resulted in strong inhibition of their ability to form soft agar colonies and in marked suppression of tumorigenicity in the subcutaneous tissue of immune-deficient mice. This is despite inconsistent alteration in the proliferation rate on plastic surfaces. Tumor cells explanted from occasional xenograft tumors formed by the Met-overexpressing H1264 cells also demonstrated marked down-regulation of the receptor protein levels as compared to the transplanted cells. The results suggest that constitutive overexpression of Met receptor may negatively regulate the malignancy of certain human lung cancer cells.     

Autocrine Growth Loop of The Epidermal Growth Factor Receptor in Normal and Immortalized Human Bronchial Epithelial Cells

Epidermal growth factor (EGF) is a potent growth factor for human normal bronchial epithelial (HBE) cells and lung cancer cells, which often demonstrate an EGF receptor (EGFR) autocrine loop. We have found that HBE cells are capable of proliferating in basal medium without EGF supplementation, and this suggests the probable presence of an active EGFR autocrine loop in non-neoplastic HBE cells. Northern blot hybridization shows that the parental and immortalized HBE cells express comparable and high levels of mRNA for EGFR, transforming growth factor-alpha (TGF-α), and amphiregulin (AR), but not EGF. Incubation with neutralizing monoclonal antibodies (mAb) against EGFR partially inhibits the growth of these cells. Immunohistochemistry shows that HBE cells express the TGF-α peptidein vitroandin vivo,however, neutralizing mAbs against TGF-α fail to inhibit their proliferation. In contrast, AR stimulates the growth of HBE cells. Thus, several EGF-family ligands appear to be involved functionally in the EGFR autocrine growth loop in HBE cells.     

Regulation of 5-hydroxytryptamine-induced signal transduction in canine cultured aorta smooth muscle cells by phorbol ester.

Regulation of the increase in inositol phosphates (IPs) production and intracellular Ca2+ concentration ([Ca2+]i) by protein kinase C (PKC) was investigated in cultured canine aorta smooth muscle cells (ASMCs). Stimulation of ASMCs by 5-hydroxytryptamine (5-HT) led to IPs formation and caused an initial transient [Ca2+]i peak followed by a sustained elevation of [Ca2+]i in a concentration-dependent manner. Pretreatment of ASMCs with phorbol 12-myristate 13-acetate (PMA) for 30 min almost abolished the 5-HT-induced IPs formation and Ca2+ mobilization. This inhibition was reduced after long-term incubating the cells with PMA. Prior treatment of ASMCs with staurosporine or GF109203X, PKC inhibitors, inhibited the ability of PMA to attenuate 5-HT-induced responses, suggesting that the inhibitory effect of PMA is mediated through the activation of PKC. In parallel with the effect of PMA on the 5-HT-induced IP formation and Ca2+ mobilization, the translocation and down-regulation of PKC isozymes were determined by Western blotting with antibodies against different PKC isozymes. The results revealed that treatment of ASMCs with PMA for various times, translocation of PKC-alpha, betaI, betaII, delta, epsilon, theta, and zeta isozymes from the cytosol to the membrane was seen after 5-min, 30-min, 2-h, and 4-h treatment. However, 24-h treatment caused a partial down-regulation of these PKC isozymes. In conclusion, these results demonstrate that translocation of PKC-alpha, betaI, betaII, delta, epsilon, theta, and zeta induced by PMA caused an attenuation of 5-HT-induced IPs accumulation and Ca2+ mobilization in ASMCs.     

A heat transfer study on packed bed reactors of immobilized glucoamylase

Enzymes are generally sensitive to temperature changes. Porous glass particles used for glucoamylase immobilization are poor thermal conductors and a non-uniform temperature distribution can conceivably develop in a packed bed reactor of immobilized glucoamylase on porous beads. This study was made to determine experimentally the temperature and concentration profiles in an immobilized glucoamylase column. This work provides a procedure for examining possible heat effects on reactor column performance in enzyme applications.     

Heme Oxygenase-1 Expression Affects Murine Abdominal Aortic Aneurysm Progression

Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is a cytoprotective enzyme upregulated in the vasculature by increased flow and inflammatory stimuli. Human genetic data suggest that a diminished HO-1 expression may predispose one to abdominal aortic aneurysm (AAA) development. In addition, heme is known to strongly induce HO-1 expression. Utilizing the porcine pancreatic elastase (PPE) model of AAA induction in HO-1 heterozygous (HO-1^+/-, HO-1 Het) mice, we found that a deficiency in HO-1 leads to augmented AAA development. Peritoneal macrophages from HO-1^+/- mice showed increased gene expression of pro-inflammatory cytokines, including MCP-1, TNF-alpha, IL-1-beta, and IL-6, but decreased expression of anti-inflammatory cytokines IL-10 and TGF-beta. Furthermore, treatment with heme returned AAA progression in HO-1 Het mice to a wild-type profile. Using a second murine AAA model (Ang II-ApoE^-/-), we showed that low doses of the HMG-CoA reductase inhibitor rosuvastatin can induce HO-1 expression in aortic tissue and suppress AAA progression in the absence of lipid lowering. Our results support those studies that suggest that pleiotropic statin effects might be beneficial in AAA, possibly through the upregulation of HO-1. Specific targeted therapies designed to induce HO-1 could become an adjunctive therapeutic strategy for the prevention of AAA disease.     

Xylitol production from hybrid poplar wood chips pretreated by the ammonia steeping process

Xylitol production from hemicellulosic feedstocks by a Candida sp. was inhibited by various compounds present in untreated hydrolysates. Using a pretreatment of wood chips by the ammonia steeping process, 33.6 g xylitol/L was produced from 50 g xylose/L after 5 h giving a productivity of 5.38 g/Lh and yield of 0.74 g/g. Comparable xylitol productivities were obtained upon treatment of hydrolysate with Amberlite weak base anion exchange resin.