Objective-To evaluate expression of cyclooxygenase (COX)-1 and COX-2 in the
urinary bladder epithelium of clinically normal dogs and in transitional c
ell carcinoma cells of dogs.
Animals-21 dogs with transitional cell carcinoma of the urinary bladder and
8 dogs with clinically normal urinary bladders.
Procedure COX-1 and COX-2 were evaluated by use of isoform-specific antibod
ies with standard immunohistochemical methods.
Results-COX-1, but not COX-2, was constitutively expressed in normal urinar
y bladder epithelium; however, COX-2 was expressed in neoplastic epithelium
in primary tumors and in metastatic lesions of all 21 dogs and in new prol
iferating blood vessels in 3 dogs. Also, COX-1 was expressed in the neoplas
tic cells.
Conclusions and Clinical Relevance-Lack of expression of COX-2 in normal bl
adder epi thelium and its substantial expression in transitional cell carci
noma cells suggest that. this isoform may be involved in tumor cell growth.
Inhibition of COX-2 is a likely mechanism of the antineoplastic effects of
non steroidal antiinflammatory drugs.