|Title||The chemopreventive agent alpha-difluoromethylornithine blocks Ki-ras-dependent tumor formation and specific gene expression in Caco-2 cells.|
|Publication Type||Journal Article|
|Year of Publication||2004|
|Authors||Ignatenko NA, Zhang H, Watts GS, Skovan BA, Stringer DE, Gerner EW|
|Date Published||2004 Apr|
|Keywords||Animals, Antineoplastic Agents, Caco-2 Cells, Cell Communication, Cell Movement, Colonic Neoplasms, Eflornithine, Gene Expression Profiling, Gene Expression Regulation, Genes, ras, Humans, Laminin, Mice, Mice, SCID, Neoplasm Proteins, Oligonucleotide Array Sequence Analysis, Ornithine Decarboxylase, Ornithine Decarboxylase Inhibitors, Transfection|
Mutation of the Kirsten-ras (Ki-ras) proto-oncogene occurs frequently in colorectal cancers. alpha-Difluoromethylornithine (DFMO), an irreversible inhibitor of the polyamine biosynthetic enzyme, ornithine decarboxylase (ODC), inhibits Ki-ras transformation and colon tumorigenesis in carcinogen-treated animal models by mechanisms yet to be elucidated. Caco-2 cells transfected with an activated Ki-ras, but not parental cells, formed tumors in severe combined immunodeficient (SCID) mice. DFMO treatment (2% in drinking water) prevented tumor growth. Gene expression profiling was performed to identify Ki-ras-and DFMO-dependent patterns of gene expression. Microarray results were validated with real-time or semi-quantitative RT-PCR and/or Western blot analysis. Genes upregulated in Caco-2 cells expressing an activated Ki-ras encoded cytoskeletal-, transport-, protease-, and gap junction-associated proteins. These genes are important for normal development and maintenance of colonic epithelial tissue. Caco-2 cells transfected with an activated Ki-ras displayed increased expression of the integrin alpha 1 (INGA1) and enhanced cell migration on laminin. These parameters were unaffected by DFMO, but Ki-ras-dependent migration was inhibited by INGA1 antibodies. Other Ki-ras-dependent, but DFMO-independent, genes included transglutaminase (TGase) and kallikrein 6 (KLK6). Ki-ras-transfected cells also expressed increased levels of connexin43 (Cx43) (RNA and protein), tight junction protein, and endothelin 1. DFMO reversed these increases. The results indicated that the Ki-ras oncogene caused changes in experimental cell migration and cell-cell communication genes and that some of these changes could be reversed by DFMO.
|Alternate Journal||Mol. Carcinog.|
|Grant List||P30 CA023074 / CA / NCI NIH HHS / United States |
CA 23074 / CA / NCI NIH HHS / United States
P30 ES006694 / ES / NIEHS NIH HHS / United States
CA 95060 / CA / NCI NIH HHS / United States
CA 72008 / CA / NCI NIH HHS / United States
The chemopreventive agent alpha-difluoromethylornithine blocks Ki-ras-dependent tumor formation and specific gene expression in Caco-2 cells.
Faculty Member Reference:
George Watts, Ph.D.