The scientists further reported that many of the genes, whose expression is changed by celecoxib, were tied to the immune system and the inflammatory response.
Together, the results offer specific molecular evidence for how this drug may suppress the formation of colon polyps, which often serve as a marker for early colon cancer.
"Analysis of these celecoxib-induced changes in gene expression suggests that in the 'normal' colon, this COX-2 inhibitor may act directly or indirectly to suppress the immune response and early steps of inflammation," said Oleg Glebov, Ph.D., a cancer genetics researcher at the National Cancer Institute.
As described by the scientists, a portfolio of 173 genes isolated in the normal mucosal lining of the colon is differentially expressed in patients genetically at risk for hereditary nonpolyposis colon cancer or (HNPCC). Also known as Lynch Syndrome, patients with this inherited disorder are at higher risk of developing colorectal cancer and certain other types of cancer, such as ovarian or endometrial cancers. Only about three percent of all cases of colon cancer stem from this condition.
Glebov and his colleagues noted that patients taking higher doses of celecoxib (800 mg twice a day) experienced more dramatic effects than those on lower doses (200 mg twice a day). Specifically, the drug affected genes involved with cell signaling, cell adhesion, response to stress, TGF-beta signaling, and the regulation of cell death, or apoptosis.
"We found that treatment of patients with celecoxib led to changes in more than 1,400 genes in the healthy colon," Glebov said. "Of those genes, a specific set of 173 forms a signature portfolio that accurately identifies the colonic biopsies from patients taking the nonsteroidal anti-inflammatory drug (NSAID) celecoxib."
Joining Glebov in pursuit of these studies were Luz Rodriguez, Kenneth Nakahara, Jean Jenkins, Casey-Jo Humbyrd, Janet Cliatt, Ernest Hawk and Ilan Kirsch, NCI, Bethesda, Md.; Patrick Lynch, Sherry Patterson, UT M. D. Anderson Cancer Center, Houston, Texas; Henry Lynch, Creighton University, Omaha, Neb.; Peter Soballe, John DeNobile National Naval Medical Center, Bethesda, Md.; Steven Gallinger, University of Toronto, Toronto, ON; Aby Buchbinder, Pharmacia, Peapack, N.J.; and Gary Gordon, Ovation Pharma, Lincolnshire, Ill.
Founded in 1907, the American Association for Cancer Research is a professional society of more than 24,000 laboratory, translational, and clinical scientists engaged in all areas of cancer research in the United States and in more than 60 other countries. AACR's mission is to accelerate the prevention and cure of cancer through research, education, communication, and advocacy. Its principal activities include the publication of five major peer-reviewed scientific journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention. AACR's Annual Meetings attract more than 15,000 participants who share new and significant discoveries in the cancer field. Specialty meetings, held throughout the year, focus on the latest developments in all areas of cancer research.