Celecoxib and curcumin synergistically inhibit the growth of colorectal cancer cells.
OBJECTIVE
Multiple studies have indicated that cyclooxygenase-2 (COX-2) inhibitors may prevent colon cancer, which is one of the leading causes of cancer death in the western world. Recent studies, however, showed that their long-term use may be limited due to cardiovascular toxicity. This study aims to investigate whether curcumin potentiates the growth inhibitory effect of celecoxib, a specific COX-2 inhibitor, in human colon cancer cells.


METHODS
HT-29 and IEC-18-K-ras (expressing high levels of COX-2), Caco-2 (expressing low level of COX-2), and SW-480 (no expression of COX-2) cell lines were exposed to different concentrations of celecoxib (0-50 micromol/L), curcumin (0-20 micromol/L), and their combination. COX-2 activity was assessed by measuring prostaglandin E(2) production by enzyme-linked immunoassay. COX-2 mRNA levels were assessed by reverse transcription-PCR.


RESULTS
Exposure to curcumin (10-15 micromol/L) and physiologic doses of celecoxib (5 micromol/L) resulted in a synergistic inhibitory effect on cell growth. Growth inhibition was associated with inhibition of proliferation and induction of apoptosis. Curcumin augmented celecoxib inhibition of prostaglandin E(2) synthesis. The drugs synergistically down-regulated COX-2 mRNA expression. Western blot analysis showed that the level of COX-1 was not altered by treatment with celecoxib, curcumin, or their combination.


CONCLUSIONS
Curcumin potentiates the growth inhibitory effect of celecoxib by shifting the dose-response curve to the left. The synergistic growth inhibitory effect was mediated through a mechanism that probably involves inhibition of the COX-2 pathway and may involve other non-COX-2 pathways. This synergistic effect is clinically important because it can be achieved in the serum of patients receiving standard anti-inflammatory or antineoplastic dosages of celecoxib.
Lev-Ari
Shahar
S
Department of Cancer Prevention, Tel Aviv Medical Center, Israel.
Strier
Ludmila
L
Kazanov
Diana
D
Madar-Shapiro
Liora
L
Dvory-Sobol
Hadas
H
Pinchuk
Ilya
I
Marian
Brigitte
B
Lichtenberg
Dov
D
Arber
Nadir
N
D000704:Analysis of Variance; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D018938:Caco-2 Cells; D000068579:Celecoxib; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D003474:Curcumin / Q000494:pharmacology*; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D019073:HT29 Cells; D006801:Humans; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013449:Sulfonamides / Q000494:pharmacology*; D013997:Time Factors
D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D008565:Membrane Proteins; D011720:Pyrazoles; D012333:RNA, Messenger; D013449:Sulfonamides; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D003474:Curcumin; D000068579:Celecoxib