Antiproliferative effect of the combined treatment of celecoxib with docetaxel liposomes in human lung adenocarcinoma cell line

5315 The purpose of the study was to investigate the effect of combined treatment of celecoxib with docetaxel liposomes on the cell proliferation, apoptosis and expression of various genes involved in the cell proliferation in A549 lung tumor cell line. Docetaxel liposomes were prepared using dipalmitoylphosphatidylcholine: dipalmitoylphosphatidylethanolamine coupled to polyethylene glycol 2000: phosphatidylcholine: cholesterol: docetaxel by film evaporation method. The drug content in docetaxel liposomes was estimated using HPLC. The lung tumor A549 cells were treated with celecoxib alone (10 μg/ml), docetaxel liposomes (0.01 μg/ml) alone and the combination of celecoxib (10 μg/ml) with docetaxel liposomes (0.01 μg/ml) and the cytotoxicity and apoptosis was assessed by crystal violet dye uptake method and TUNEL staining method, respectively. The expression of cyclooxygenase (COX)-2 and peroxisome proliferator activated receptor (PPAR)-γ was elucidated by RT-PCR. Further, DNA microarray analysis using cancer pathfinder gene array was used to study the expression of various genes involved in cell proliferation and apoptosis. Our results indicate that the delivery of docetaxel using liposomes had a lower IC 50 value (0.009 μg/ml) against docetaxel delivered as a solution (0.023 μg/ml). The combined treatment of celecoxib with docetaxel liposomes showed a great antiproliferative effect (IC 50 0.004 μg/ml) as compared to all other treatments. TUNEL analysis showed more than 50% apoptosis in cells treated with celecoxib with docetaxel liposomes, whereas celecoxib or docetaxel liposmes showed only 30% apoptosis. There was a significant increase in the expression of PPAR-γ by the combination of celecoxib with docetaxel liposomes, whereas the same combination has minimal effect on COX-2 expression as studied by RT-PCR. DNA microarray analysis indicated that upregulation of various genes such as tumor protein p53, epidermal growth factor receptor and down regulation of cyclin dependent kinase (CDK4) and cyclin dependent kinase inhibitor (p27kip1). In conclusion, our study indicates that the combination treatment of celecoxib with docetaxel liposomes had a greater in-vitro antitumor effect, which may be further explored in the treatment of lung cancer.