129 research outputs found
Resistance to TGF beta in SV40 large T-immortalized rat intestinal epithelial cells is associated with down-regulation of TGF beta type I receptor
No full textA new continuous cell line designated ESKI-1 was established by transfection of rat fetal intestinal epithelial cells with ecotropic retroviruses containing SV40 large T oncogene. The ESKI-1 cell line exhibits morphologic features of an epithelial cell line and expresses the OCI-5 and cytokeratin 8 transcripts associated with epithelial cells in the small intestine. Signal transduction and proliferation responses to TGF beta has been characterized in ESKI-1 cells, in comparison with the spontaneously-immortalized IEC cell lines originating from neonatal rat duodenum and ileum. ESKI-1 express both TGF alpha and TGF beta. However, despite a marked increase in TGF beta-stimulated p78 kinase activity observed in ESKI-1 and IEC cells, TGF beta did not modulate growth, or extracellular matrix expression in ESKI-1 cells. Resistance to growth modulation was associated with downregulation of TGF beta. Type I receptor expression in the SV40 large T-immortalized cells. Thus, proliferative resistance to TGF beta inhibition can result from depletion of the TGF beta type I receptor and disruption of the TGF beta signaling pathway downstream the p78 serine/threonine kinase. These molecular defects constitute two early events during the SV40LT-mediated immortalization and neoplastic progression of the intestinal epithelia
Trefoil peptides as proangiogenic factors in vivo and in vitro: Implication of cyclooxygenase-2 and EGF receptor signaling
No full textWe previously established that the trefoil peptides (TFFs) pS2, spasmolytic polypeptide, and intestinal trefoil factor are involved in cellular scattering and invasion in kidney and colonic cancer cells. Using the chorioallantoic membrane (CAM) assay and the formation of tube-like structures by human umbilical vein endothelial cells (HUVEC) plated on the Matrigel matrix substratum, we report here that TFFs are proangiogenic factors. Angiogenic activity of TFFs is comparable to that induced by vascular endothelial growth factor, leptin, and transforming growth factor-α. Stimulation of angiogenesis by pS2 in the CAM assay is blocked by pharmacological inhibitors of cyclooxygenase COX-2 (NS-398) and epidermal growth factor receptor (EGF-R) tyrosine kinase (ZD1839), but is independent of KDR/Flk-1 and thromboxane A2 receptors. In contrast, the morphogenic switch induced by pS2 in HUVEC cells could be inhibited by the specific KDR heptapeptide antagonist ATWLPPR and by inhibitors of COX-2 and EGF-R signaling. These results implicate TFFs in the formation of new blood vessels during normal and pathophysiological processes linked to wound healing, inflammation, and cancer progression in the digestive mucosa and other human solid tumors associated with aberrant expression of TFFs. - Rodrigues, S., Van Aken, E., Van Bocxlaer, S., Attoub, S., Nguyen, Q.-D., Bruyneel, E., Westley, B. R., May, F. E. B., Thim, L., Mareel, M., Gespach, C., Emami, S. Trefoil peptides as proangiogenic factors in vivo and in vitro: implication of cylooxygenase-2 and EGF receptor signaling
Enterocyte differentiation is compatible with SV40 large T expression and loss of p53 function in human colonic Caco-2 cells. Status of the pRb1 and pRb2 tumor suppressor gene products
No full textTransfer of the SV40 large-T (LT) oncogene into isolated human and murine intestinal epithelial cells induced alterations of the ultrastructural organization and polarization of the resulting immortalized cell lines. We now demonstrate that the functional expression of the SV40 LT antigen in Caco-2 cells did not alter phenotypic markers of differentiation, including expression of villin, sucrase-isomaltase, brush border and dome formation. As compared to parental cells, the transfected Caco-2LT9 cells exhibited similar growth curves and no invasive properties in vitro. The major oncogenic function of the SV40 LT antigen in transfected Caco-2 cells is associated with reduced latency times necessary for the manifestation of tumors in athymic nude mice. The Caco-2 cell line contained deleted and mutant p53 alleles (stop codon in position 204) and has no detectable truncated p53 protein by Western blot. Molecular complexes between the SV40 LT antigen and the retinoblastoma-related proteins pRb1 and Rb2 were clearly identified at the different phases of the growth curve. When compared to normal human colonic crypts, Caco-2 cell differentiation is related to partial redistribution of pRb1 into hypophosphorylated, anti-proliferative forms. The pRb2 protein is found elevated in a subset of human colorectal tumors and their corresponding liver metastases. We conclude that: (1) Caco-2 cells exert a dominant control against the oncogenic functions of the LT antigen; (2) loss of p53 function is not restrictive for the establishment of polarity and differentiation of the enterocyte lineage; (3) the levels and phosphorylation status of the Rb1 and Rb2 proteins may play important roles in the proliferation and differentiation of normal and neoplastic human colonic mucosa
Development of sensitivity to cAMP-inducing hormones in the rat stomach
No full text Development of cAMP responses to secretin, pancreatic glucagon, and histamine was measured in gastric glands of fetal (day 20), postnatal (days 1-30), and adult rats (day 65). cAMP stimulation by these hormones was already detected on day 20 of gestation. cAMP generation showed biphasic variations during the 1st days of life and at the onset of weaning (day 20). Anticipated weaning at day 14 triggered precocious maturation (efficacies) of the cAMP-generating systems sensitive to secretin, glucagon, and histamine without changing the potencies of the hormones. During development, the general characteristics (potency and pharmacological or regulatory properties) of the receptor-cAMP systems studied were comparable with those evidenced in adult rats. At days 5, 20, and 65, vasoactive intestinal peptide and the peptide having N-terminal histidine and C-terminal isoleucine amide (PHI) were about 100 times less potent than secretin (EC50 = 1.5 X 10(-9) M secretin). The histamine action could be blocked by the competitive H2-receptor antagonist cimetidine (70-100% inhibition) as well as by the noncompetitive inhibitor somatostatin (37-62% inhibition). The data indicate that these regulatory hormones (secretin, glucagon(s), histamine, and somatostatin) might have a direct effect on gastric glands and may modulate their biological activities (metabolism, differentiation, proliferation, and exocrine and endocrine secretions) from the neonatal period in rats. The important physiological role of weaning on the final maturation of the cAMP-generating systems in rat gastric glands is underlined. </jats:p
Neurotensin receptor 1 determines the outcome of non-small cell lung cancer
No full textPURPOSE: This study aimed to investigate the role of the neurotensin/neurotensin receptor I (NTSR1) complex in non-small cell lung cancer (NSCLC) progression.
EXPERIMENTAL DESIGN: The expression of neurotensin and NTSR1 was studied by transcriptome analysis and immunohistochemistry in two series of 74 and 139 consecutive patients with pathologic stage I NSCLC adenocarcinoma. The findings were correlated with clinic-pathologic features. Experimental tumors were generated from the malignant human lung carcinoma cell line A459, and a subclone of LNM35, LNM-R. The role of the neurotensin signaling system on tumor growth and metastasis was investigated by small hairpin RNA-mediated silencing of NTSR1 and neurotensin.
RESULTS: Transcriptome analysis carried out in a series of 74 patients showed that the positive regulation of NTSR1 put it within the top 50 genes related with relapse-free survival. Immunohistochemistry revealed neurotensin- and NTSR1-positive staining in 60.4% and 59.7% of lung adenocarcinomas, respectively. At univariate analysis, NTSR1 expression was strongly associated with worse 5-year overall survival rate (P = 0.0081) and relapse-free survival (P = 0.0024). Multivariate analysis showed that patients over 65 years of age (P = 0.0018) and NTSR1 expression (P = 0.0034) were independent negative prognostic factors. Experimental tumor xenografts generated by neurotensin- and NTSR1-silenced human lung cancer cells revealed that neurotensin enhanced primary tumor growth and production of massive nodal metastasis via autocrine and paracrine regulation loops.
CONCLUSION: NTSR1 expression was identified as a potential new prognostic biomarker for surgically resected stage I lung adenocarcinomas, as NTSR1 activation was shown to participate in lung cancer progression
Oxyntomodulin (glucagon-37 or bioactive enteroglucagon): A potent inhibitor of pentagastrin-stimulated acid secretion in rats
No full text
UV-induced fragmentation of Cajal bodies
No full textThe morphology and composition of subnuclear organelles, such as Cajal bodies (CBs), nucleoli, and other nuclear bodies, is dynamic and can change in response to a variety of cell stimuli, including stress. We show that UV-C irradiation disrupts CBs and alters the distribution of a specific subset of CB components. The effect of UV-C on CBs differs from previously reported effects of transcription inhibitors. We demonstrate that the mechanism underlying the response of CBs to UV-C is mediated, at least in part, by PA28? (proteasome activator subunit ?). The presence of PA28? in coilin-containing complexes is increased by UV-C. Overexpression of PA28?, in the absence of UV-C treatment, provokes a similar redistribution of the same subset of CB components that respond to UV-C. RNA interference–mediated knockdown of PA28? attenuates the nuclear disruption caused by UV-C. These data demonstrate that CBs are specific nuclear targets of cellular stress-response pathways and identify PA28? as a novel regulator of CB integrity. © 2006 Cioce et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/). </p
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