Cyclooxygenase-2 expression in animal cancers.
Cyclooxygenase (COX; also known as prostaglandin endoperoxide synthase) is a key enzyme in the biochemical pathway leading to the synthesis of prostaglandins. A large amount of epidemiological and experimental evidence supports a role for COX-2, the inducible form of the enzyme, in human tumorigenesis, notably in colorectal cancer. COX-2 mediates this role through the production of PGE(2) that acts to inhibit apoptosis, promote cell proliferation, stimulate angiogenesis, and decrease immunity. Similarly, COX-2 is believed to be involved in the oncogenesis of some cancers in domestic animals. Here, the author reviews the current knowledge on COX-2 expression and role in cancers of dogs, cats, and horses. Data indicate that COX-2 upregulation is present in many animal cancers, but there is presently not enough information to clearly define the prognostic significance of COX-2 expression. To date, only few reports document an association between COX-2 expression and survival, notably in canine mammary cancers and osteosarcomas. Some evidence suggests that COX inhibitors could be useful in the prevention and/or treatment of certain cancers in domestic animals, the best example being urinary transitional cell carcinomas in dogs. However, determination of the levels of COX-2 in a tumor does not appear to be a good prognostic factor or a good indicator for the response to nonsteroidal anti-inflammatory drug therapy. Clearly, additional research, including the development of in vitro cell systems, is needed to determine if COX-2 expression can be used as a reliable prognostic factor and as a definite therapeutic target in animal cancers.
Doré
M
M
Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, St-Hyacinthe, Québec, Canada. monique.dore@umontreal.ca
D000818:Animals; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D006801:Humans; D009369:Neoplasms / Q000201:enzymology* / Q000378:metabolism
D051546:Cyclooxygenase 2