RESUMO
BACKGROUND: Cyclooxygenase-2 (Cox-2) has been found to be overexpressed in several types of human cancers and its role in tumorigenesis has been proposed. The aim of this study was to investigate the effects of the cyclooxygenase inhibitor diclofenac on the growth of murine C-26 colon carcinoma cells. MATERIALS AND METHODS: Expression of Cox-2 mRNA and protein was examined by RT-PCR analysis and immunohistochemistry, respectively. By using MTT-assay, we examined the effects of diclofenac at various concentrations on the growth of C-26 cells in vitro. The effect of diclofenac on the growth of the C-26 tumor in syngeneic mice was also investigated. RESULTS: By RT-PCR, Cox-2 mRNA was detected in C-26 cells. Cox-2 protein was localized to C-26 cells and treatment with diclofenac resulted in apoptotic cell death in a dose-dependent manner. Diclofenac administered in drinking water resulted in growth inhibition of C-26 tumor in mice and correlated with plasma levels of both PGE2 and TXB2. CONCLUSION: Our data show that diclofenac may be a potential agent for the prevention and treatment of human colon cancer.
Assuntos
Antineoplásicos/farmacologia , Neoplasias do Colo/tratamento farmacológico , Inibidores de Ciclo-Oxigenase/farmacologia , Diclofenaco/farmacologia , Animais , Divisão Celular/efeitos dos fármacos , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Ciclo-Oxigenase 2 , Inibidores de Ciclo-Oxigenase 2 , Dinoprostona/antagonistas & inibidores , Dinoprostona/biossíntese , Feminino , Isoenzimas/biossíntese , Isoenzimas/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Prostaglandina-Endoperóxido Sintases/biossíntese , Prostaglandina-Endoperóxido Sintases/genética , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células Tumorais CultivadasRESUMO
BACKGROUND: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is expressed by immune cells and has been shown to play an important role in tumor surveillance due to its ability to induce apoptosis in various transformed cells. Interferon gamma (IFN-gamma), a multipotent cytokine with broad stimulatory effects on anti-tumoral immune reactions, may exert its cytotoxic activity directly on tumor cells or indirectly via stimulation of effector cells. This study was designed to determine the effect of IFN-gamma on TRAIL-mediated apoptosis in human colon carcinoma cell lines. MATERIALS AND METHODS: Cytotoxicity was assessed by MTT-assay. Expression of death receptors was measured by reverse transcriptase polymerase chain reaction. Apoptosis was assessed by caspase-8 immunoblot, DNA fragmentation and morphological studies. RESULTS: Treatment with TRAIL resulted in detectable cytotoxicity within 5 hours and was enhanced in a dose-dependent manner. When cells were pretreated with IFN-gamma, the cytotoxic effect of TRAIL increased significantly. Treated cells showed a typical apoptotic morphology that was accompanied by internucleosomal cleavage of DNA. Up-regulation of caspase-8 expression and activation were detected as a result of pretreatment with IFN-gamma and subsequent apoptosis mediated by TRAIL. CONCLUSION: Our results demonstrated that IFN-gamma sensitises human colon carcinoma cells to TRAIL-mediated apoptosis, partly by elevated caspase-8 expression.