Cyclooxygenase-2 is thought to play a role in invasion and metastases in many cancers, yet the mechanisms are unclear. We have demonstrated decreased tumor growth of lung adenocarcinoma in an orthotopic murine model with a selective cyclooxygenase-2 (COX-2) inhibitor. Our goal was to determine the effects of COX-2 inhibition on NSCLC proliferation, motility, and migration in vitro as an indicator of tumor metastatic potential.
A549 lung adenocarcinoma cells (ATCC) were cultured using a standard cell culture protocol. RT-PCR was performed to determine basal COX-2 expression. Localization of expression patterns were confirmed with immunofluorescence. Proliferation, motility, and migration assays were performed in triplicate and cells treated with vehicle or celecoxib at 10 microM, 25 microM or 50 microM. Cell proliferation was determined utilizing an MTS assay. A wound scratch motility assay was performed and assessed at 24 and 48 hours using phase-contrast microscopy. Cell migration was carried out in 24 well transwell migration chambers with 8 micron pores.
A549 cells demonstrated expression of COX-2 by RT-PCR as well as immunofluorescence staining which was localized to the cytoplasm. Cell proliferation was inhibited by celecoxib in a dose-dependent manner on MTS assay at doses exceeding 25 microM (p<0.05). Cell migration was similarly reduced by celecoxib in a dose-dependent manner by 46%, 60%, and 99% at 10 microM, 25 microM, and 50 microM respectively (p<0.05). By wound scratch assay, untreated cells were able to achieve confluence by 48 hours post-wound while cells treated with celecoxib at 50 microM demonstrated decreased motility.
Selective COX-2 blockade results in decreased tumor cell proliferation at higher doses while motility and migration are decreased even at low concentrations of celecoxib in vitro. This combined effect of COX-2 inhibition on tumor cells may result in decreased metastatic potential of NSCLC.
Chronic low dose COX-2 inhibition has the potential to retard the progression of disease in patients with lung cancer.
L.M. Backhus, None.