Back to 85th Annual Meeting
Back to Program Outline

L7. Di-methyl-celecoxib as a novel non-COX-2 therapy in the treatment of lung cancer
Leah M Backhus, Nicos A Petasis, Jasim Uddin, Robert D Bart, III, Yuanguang G Lin, Vaughn A Starnes, Ross M Bremner; Los Angeles, CA

Objectives:
The cyclo-oxygenase 2 (COX-2) enzyme is over-expressed in many tumors and has become a therapeutic target in the treatment of cancer. COX-2 blockade results in increased apoptosis, decreased angiogenesis, and inhibition of invasion both in vitro and in vivo. There is growing evidence that the anti-tumor effects of selective COX-2 inhibitors occur via both COX-2 dependent and independent pathways. The goal of this study was to further investigate these pathways using celecoxib, (COX-2 specific inhibitor) and 2,5-dimethyl celecoxib (DMC), which was modified specifically to eliminate COX-2 enzyme inhibitory activity, while potentially maintaining anti-neoplastic properties.
Methods:
2,5-Dimethyl celecoxib was synthesized similarly to celecoxib. A non-small cell lung cancer cell line (A549) was obtained from ATCC and maintained under routine cell culture conditions. Cells were treated with vehicle, celecoxib or DMC in various concentrations. Cells were lysed and COX-2 expression confirmed by PCR as well as western blot. PGE2 production was quantified by ELISA as a means to assess relative COX-2 activity. Cell proliferation was assessed by MTS assay. Cell migration was performed using transwell inserts with 8 um pores (Corning) which were coated with a layer of extracellular matrix for invasion experiments. All experiments were carried out in triplicate and a p-value of 0.05 was considered significant.
Results:
A549 had a high level of COX-2 expression by both PCR and western blot. PGE2 production was increased by treatment with IL1-beta. The addition of celecoxib at both high and low doses suppressed IL1-beta-stimulated PGE2 production. PGE2 levels remained elevated after the addition of DMC in both concentrations tested. Both celecoxib and DMC decreased tumor cell proliferation in a dose-dependent manner. The IC50 for celecoxib and DMC were 72 uM and 46 uM respectively. Treatment with DMC at 5 uM, 10 uM, and 25 uM resulted in significantly decreased tumor cell migration by 45%, 53% and 81% (p<0.01) as well as decreased tumor cell invasion by 40%, 66%, and 99% (p<0.01).
Conclusions:
DMC is a novel structural analog of celecoxib that lacks COX-2 inhibitory activity but exhibits significant anti-neoplastic effects comparable to the parent compound. This suggests that many of the antineoplastic activities of celecoxib are COX-2 independent, and that therapeutic strategies can be developed without the side-effects of COX-2 blockade. Further in vivo studies are indicated to understand the mechanisms involved and are in progress.

Back to 85th Annual Meeting
Back to Program Outline