Increased cyclooxygenase-2 levels in carcinogen-induced rat colonic tumors

R. N. DuBois, A. Radhika, B. S. Reddy, A. J. Entingh

Research output: Contribution to journalArticlepeer-review

443 Scopus citations


Background and Aims: Multiple studies show that continuous use of nonsteroidal anti-inflammatory drugs (NSAIDs) lowers the risk of colon cancer in humans and carcinogen-treated rodents. One target for NSAIDs is cyclooxygenase (COX), and two isoforms of this enzyme have been identified: COX-1 and COX-2. The present study was undertaken to determine if there is differential expression of COX in colonic tumors in azoxymethane-treated rats. Methods: COX-1 and COX-2 messenger RNA levels were determined by Northern blot analysis of total RNA isolated from colonic tumors and normal adjacent mucosa. COX-2 protein levels were determined by Western blotting analysis. Quantitation of relative band densities was performed using standard densitometry scanning techniques. Results: There was a marked increase in COX-2 RNA levels in six of six of the colonic tumors compared with paired normal mucosa. In contrast, there was equivalent intensity of the COX-1 RNA transcript between the normal mucosa and tumor in all of the specimens examined. Western blotting analysis showed an increase in the level of the COX-2 protein in four of five of the colonic tumor samples. Conclusions: COX-2 but not COX-1 gene expression is markedly elevated in most colonic tumors examined in azoxymethane-treated rodents. COX-2 may provide a target for chemopreventive strategies for colorectal cancer.

Original languageEnglish (US)
Pages (from-to)1259-1262
Number of pages4
Issue number4
StatePublished - 1996
Externally publishedYes

ASJC Scopus subject areas

  • Hepatology
  • Gastroenterology


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