Opioid growth factor tonically inhibits human colon cancer cell proliferation in tissue culture

摘要: Native opioid peptides serve as growth factors in a number of normal and neoplastic cells tissues, including the prevention delayed human colon cancer xenografts nude mice. This study examined hypothesis that opioids exert direct inhibitory influence on tumor cell by use tissue culture model. The naturally occurring pentapeptide [Met5]enkephalin depressed HT-29 from 17 to 41% at 12-72 h after administration 10(-6)M concentration; consistent with previously defined nomenclature, this peptide was termed factor (OGF). OGF action exhibited dose-response relationship, reversible not cytotoxic, receptor mediated. Growth inhibition dependent serum, noted two other lines WiDr COLO 205. continually repressed because an increase when were exposed potent antagonist naltrexone or antibody OGF. Both its receptor, zeta (zeta), found immunocytochemistry, binding assays revealed nuclear-associated dissociation constant 8.9 nM maximum capacity 43 fmol/mg protein. produced secreted cells. These results lead suggestion has direct, tonic, contribute our understanding mechanisms underlying marked antitumor effect mice inoculated