title: Supra-additive growth inhibition by a celecoxib analogue and carboxyamido-triazole is primarily mediated through apoptosis.
abstract: Combination studies of celecoxib and chemotherapeutic agents suggest that combining cyclooxygenase-2 inhibitors with other agents may have supra-additive or synergistic effects on tumor growth inhibition. Carboxyamido-triazole (CAI), a voltage-independent calcium channel inhibitor, has been shown to induce growth inhibition and apoptosis in cancer cells. We found that continuous exposure to cytostatic doses of CAI and LM-1685, a celecoxib analogue, reduced the proliferation and survival of seven human cancer cell lines by at least one log (P < or = 0.001) over either agent alone. To explore the mechanism of action of this combination, we further studied the effects of LM-1685/CAI on CCL-250 colorectal carcinoma cells. We found that the supra-additive antiproliferative effects occurred throughout a range of LM-1685 doses (5-25 micromol/L) and paralleled a decrease in COX-2 activity as measured by prostaglandin E2 production. In these cells, treatment with LM-1685/CAI suppressed the extracellular signal-regulated kinase pathway within the first hour but ultimately results in high, sustained activation of ERK over a 9-day period (P = 0.0005). Suppression of cyclin D1 and phospho-AKT, and cleavage of caspase-3 and PARP were concomitant with persistent ERK activation. Addition of PD98059, a MEK-1 inhibitor, suppressed ERK activation and significantly but incompletely reversed these signaling events and apoptosis. Flow cytometry experiments revealed that the CAI/LM-1685 combination induced a 3-fold increase in apoptosis over control (P = 0.005) in 3 days. We show that the combination of CAI and LM-1685 produces a cytotoxic effect by suppressing proliferation and triggering apoptosis.
authors.affiliation: Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Winters
authors.forename: Arpita I
authors.initials: AI
authors.lastname: Mehta
authors.forename: Emanuel F
authors.initials: EF
authors.lastname: Petricoin
authors.forename: Elise C
authors.initials: EC
authors.lastname: Kohn
authors.forename: Lance A
authors.initials: LA
authors.lastname: Liotta
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology*; D000068579:Celecoxib; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D015232:Dinoprostone / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D066246:ErbB Receptors; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011720:Pyrazoles / Q000008:administration & dosage; D015398:Signal Transduction / Q000187:drug effects; D013449:Sulfonamides / Q000008:administration & dosage; D015533:Transcriptional Activation / Q000187:drug effects; D014230:Triazoles / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D002121:Calcium Channel Blockers; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007211:Indoles; C501175:LM-1685; D008565:Membrane Proteins; D011720:Pyrazoles; D013449:Sulfonamides; D014230:Triazoles; C062058:carboxyamido-triazole; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D066246:ErbB Receptors; D000068579:Celecoxib; D015232:Dinoprostone