Non-steroidal anti-inflammatory drugs with activity against either cyclooxygenase 1 or cyclooxygenase 2 inhibit colorectal cancer in a DMH rodent model by inducing apoptosis and inhibiting cell proliferation.
BACKGROUND
Standard non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer by 40-60% but the mechanism by which this occurs is uncertain. Selective cyclooxygenase 2 inhibitors are potentially ideal chemopreventive agents as they are less toxic than standard NSAIDs. No study has compared the efficacy of these drugs at clinically relevant doses in a tumour model.


OBJECTIVE
To assess the efficacy of a range of NSAIDs with varying activity against the two cyclooxygenase isoforms in a rodent colorectal carcinogen model at anti-inflammatory doses and to explore the effect of NSAIDs on the rate of tumour apoptosis and proliferation.


METHODS
Colorectal tumours were induced in six week old Sprague-Dawley rats with five weekly doses of 1,2 dimethylhydrazine. Test agents were: indomethacin 2 mg/kg/day, meloxicam 0.6 mg/kg/day, celecoxib 6 mg/kg/day, and sulindac sulphone 40 mg/kg/day. Sulindac was tested at its chemoprotective dose of 20 mg/kg/day. After 23 weeks the number and volume of tumours per animal were recorded. Histology was performed. Tumour apoptosis was quantified on haematoxylin-eosin sections. Tumour proliferation was quantified using an immunohistochemical stain for bromodexoyuridine incorporation.


RESULTS
Test agents effectively reduced the number and volume of tumours developing in the treatment period. In all groups there was an increase in the rate of tumour apoptosis and a reduced rate of proliferation.


CONCLUSIONS
These data suggest that the chemopreventive effect of NSAIDs is independent of their cyclooxygenase inhibitory profile. One potential mechanism for their action may be through induction of apoptosis and inhibition of proliferation.
Brown
W A
WA
Monash University Department of Surgery, Alfred Hospital, Melbourne, Australia. wendy.brown@med.monash.edu.au
Skinner
S A
SA
Malcontenti-Wilson
C
C
Vogiagis
D
D
O'Brien
P E
PE
D000230:Adenocarcinoma / Q000188:drug therapy*; D000236:Adenoma / Q000188:drug therapy*; D000704:Analysis of Variance; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D001973:Bromodeoxyuridine; D002455:Cell Division / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000188:drug therapy*; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000627:therapeutic use*; D007527:Isoenzymes / Q000187:drug effects; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases / Q000737:chemistry / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013194:Staining and Labeling
D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496513:Ptgs1 protein, rat; D001973:Bromodeoxyuridine