Inhibition by dietary menhaden oil of cyclooxygenase-1 and -2 in N-nitrosomethylurea-induced rat mammary tumors.

  • Authors: R Hamid, J Singh, B S Reddy, L A Cohen
  • View Affiliations

  • Published online on: Monday, March 1, 1999
  • Pages: 523-531
  • DOI: 10.3892/ijo.14.3.523

Abstract

Studies in laboratory animals and epidemiological surveys suggest a relationship between the type and amount of dietary fat and mammary cancer. One mechanism proposed to explain this relationship is modulation by dietary fat, of mammary tumor eicosanoid levels through action at the rate limiting enzyme in eicosanoid synthesis, cyclooxygenase (COX). Until recently there have been no studies which have examined COX gene expression in human breast or rodent mammary tissues. In this study we have demonstrated the presence of two immunoreactive isoforms of cyclooxygenase (COX-1 and -2), and the modulating effects of n-3 fatty acids on their expression, in N-nitrosomethylurea (NMU)-induced rat mammary tumors. Three different high fat diets were compared namely, corn oil (CO) 23%; CO 18% menhaden oil (MO) 5%; CO, 5%/MO 18%; low fat corn oil (5%) served as a control. It was found that immunoreactive COX-2 protein levels were approximately 3x higher than COX-1 levels in NMU-induced mammary tumors. Moreover, the high menhaden oil diet (rich in n-3 fatty acids) significantly suppressed both COX-1 (-28%) and COX-2 (-36%) protein levels when compared to the high corn oil diet. No differences were found among the other treatment groups when compared pair-wise or with low-fat control. The mechanism(s) by which n-3 fatty acids suppress COX-1 and COX-2 remain to be determined.
Journal Cover

March 1999
Volume 14 Issue 3

Print ISSN: 1019-6439
Online ISSN:1791-2423

2012 Impact Factor: 2.773
Ranked #30/202 Oncology
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APA
Hamid, R., Singh, J., Reddy, B., & Cohen, L. (1999). Inhibition by dietary menhaden oil of cyclooxygenase-1 and -2 in N-nitrosomethylurea-induced rat mammary tumors.. International Journal of Oncology, 14(3), 523-531.
MLA
Hamid, Singh, Reddy, and L A Cohen. "Inhibition by dietary menhaden oil of cyclooxygenase-1 and -2 in N-nitrosomethylurea-induced rat mammary tumors.." International Journal of Oncology International Journal of Oncology 14.3 (1999): 523-531.
Chicago
Hamid, Singh, Reddy, and L A Cohen. "Inhibition by dietary menhaden oil of cyclooxygenase-1 and -2 in N-nitrosomethylurea-induced rat mammary tumors.." International Journal of Oncology International Journal of Oncology 14 no. 3 (1999): 523-531.