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- Neopikhanov, V, et al.
(författare)
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40- to 100-kD protein(s) of Helicobacter pylori stimulate DNA synthesis in epithelial cell lines without affecting apoptosis
- 2000
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Ingår i: Digestion. - : S. Karger AG. - 0012-2823 .- 1421-9867. ; 61:1, s. 22-29
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Tidskriftsartikel (refereegranskat)abstract
- <i>Background:</i> Previous in vitro studies have demonstrated that water extracts and sonicates of <i>Helicobacter pylori </i>increase DNA synthesis in a small intestinal epithelial cell line. The aim of this study was to identify mitogenic factor(s) in a water extract of a <i>H. pylori</i> strain and to examine their effects on DNA synthesis and apoptosis in vitro. <i>Methods: </i>IEC-6 and FHs 74 cells were incubated for 24 h with different dilutions of a water extract of <i>H. pylori</i> (cytotoxic strain 88–23) or with 6 protein fractions obtained by gel filtration. Cells were labeled with tritiated thymidine and processed for autoradiography. DNA synthesis was evaluated by the labeling index (LI%). The proportion of IEC-6 cells undergoing apoptosis and/or necrosis was evaluated by flow cytometry using fluorescein isothiocyanate (FITC)-labeled annexin-V and propidium iodide. In vitro caspase activity was also determined as an alternative method for detection of apoptosis. <i>Results:</i> The water extract of <i>H. pylori</i> 88-23 markedly increased DNA synthesis in both epithelial cell lines (p < 0.01). A marked stimulation of DNA synthesis was also observed in IEC-6 cells incubated with fraction II- containing proteins of a molecular weight ranging between 40 and 100 kD (p < 0.01). A lesser stimulation of DNA synthesis was observed in cells incubated with higher concentrations of the other protein fractions (p < 0.01). Neither the water extract of <i>H. pylori</i> 88-23 nor the protein fraction II (40–100 kD) induced apoptosis in IEC-6 cells. <i>Conclusion:</i> A water extract of <i>H. pylori</i> 88-23 and a protein fraction containing proteins with molecular weights of 40–100 kD stimulate DNA synthesis in a rat and human small intestinal cell line. Apoptosis was unaffected by the water extract and by protein fraction II, which indicate that the <i>H. pylori</i>-derived mitogen(s) have the capacity to directly enhance epithelial cell proliferation in vitro.
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