title: Cyclooxygenase-2 expression influences the growth of human large and small cell lung carcinoma lines in athymic mice: impact of an organoselenium compound on growth regulation.
abstract: Increased expression of cyclooxygenase-2 (COX-2) significantly enhances carcinogenesis and inflammatory reactions. Regulation of COX-2 overexpression may be a reasonable target for cancer chemoprevention. We have tested the hypothesis that levels of COX-2 expression determine the growth of human lung cancer cells in nude mice. Two cell lines, NCI-H460 (non-small cell lung cancer) and NCI-H69 (small cell lung cancer) were selected because the former expresses high levels of COX-2 protein and the latter has no detectable levels. We also examined the effects of 1,4-phenylenebis(methylene)selenocyanate (p-XSC), a highly effective chemopreventive organoselenium compound and known inhibitor of COX-2 expression, in vivo, on cell growth and COX-2 expression in vitro in the NCI-H460 cancer cell line. Cells were exposed to p-XSC at levels between 10 and 100 microM for six days and showed toxicity at approximately 50 microM. Pre-exposure of NCI-H460 to non-toxic levels of p-XSC suppressed COX-2 protein expression in a dose-dependent manner. At 40 microM, p-XSC suppressed phorbol myristate acetate (PMA)-induced COX-2 expression in NCI-H460 cells by more than 66%. In vivo studies in athymic mice showed a significant difference in tumor volume between cell lines. Pre-treatment of NCI-H460 cells with a non-toxic dose of p-XSC, prior to their injection into nude mice, significantly suppressed tumor growth when compared to untreated cells. Collectively, the outcome of our in vitro and in vivo studies supports the hypothesis that levels of COX-2 expression determine the extent of human lung tumor growth in athymic mice. Therefore, inhibition of COX-2 expression by agents such as p-XSC provides a strong rationale for the development of future clinical prevention trials.
authors.affiliation: American Health Foundation, Valhalla, NY 10595, USA. kelbayoumy@aol.com
authors.forename: Karam
authors.initials: K
authors.lastname: El-Bayoumy
authors.forename: David P
authors.initials: DP
authors.lastname: Rose
authors.forename: Nick
authors.initials: N
authors.lastname: Papanikolaou
authors.forename: Joanna
authors.initials: J
authors.lastname: Leszczynska
authors.forename: Malisetty V
authors.initials: MV
authors.lastname: Swamy
authors.forename: Chinthalapally V
authors.initials: CV
authors.lastname: Rao
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D018287:Carcinoma, Large Cell / Q000188:drug therapy* / Q000201:enzymology; D018288:Carcinoma, Small Cell / Q000188:drug therapy* / Q000201:enzymology; D002455:Cell Division; D051546:Cyclooxygenase 2; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis*; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000201:enzymology; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D016566:Organoselenium Compounds / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D020033:Protein Isoforms; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D007527:Isoenzymes; D008565:Membrane Proteins; D016566:Organoselenium Compounds; D020033:Protein Isoforms; C074153:1,4-phenylenebis(methylene)selenocyanate; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases