RESUMEN
Due to the high prevalence and mortality rate of colorectal cancer (CRC), new treatment approaches like combination therapy seem to be necessary. The relationship between chronic inflammation and colorectal cancer development and progression has been shown to be important. Celecoxib, a selective COX-2 inhibitor, is the only non-steroidal anti-inflammatory drug (NSAID) that has been approved for cancer therapy and prevention. Because of cardiovascular side effects of COX-2 inhibitors, combination therapy may improve the therapeutic profile. 17-Demethoxy-17-allylamino geldanamycin (17-AAG), a heat shock protein 90 (HSP90) inhibitor, shows anti-inflammatory effects via down-regulation of the key mediators of inflammation such as Nuclear Factor κB (NF-kB), JAK/Signal Transducer and Activator of Transcription (JAK/STAT). Thus, we studied the effect(s) of combination of 17-AAG and celecoxib on HT-29 cells viability and apoptosis induction. Based on MTT results, we showed an increase in the inhibitory effect of celecoxib when combined with 17-AAG, especially at low a concentration of celecoxib. Flow cytometry analysis demonstrated that apoptosis induction is probably the mechanism of additive inhibitory effects of 17-AAG and celecoxib combination. To explore the possible mechanism of apoptosis induction by 17-AAG and celecoxib combination, levels of BAX and BCL-2 proteins were determined by western blotting. The BAX/BCL-2 ratio in the combination group was increased compared to 17-AAG or celecoxib alone, mainly via decreasing BCL-2 levels. In conclusion, 17-AAG, increased inhibitory effects of celecoxib on HT-29 cells, probably by induction of apoptosis.
Asunto(s)
Apoptosis/efectos de los fármacos , Benzoquinonas/farmacología , Celecoxib/farmacología , Proliferación Celular/efectos de los fármacos , Proteínas HSP90 de Choque Térmico/antagonistas & inhibidores , Lactamas Macrocíclicas/farmacología , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteína X Asociada a bcl-2/metabolismo , Western Blotting , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/patología , Inhibidores de la Ciclooxigenasa 2/farmacología , Citometría de Flujo , Proteínas HSP90 de Choque Térmico/metabolismo , Células HT29 , Humanos , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteína X Asociada a bcl-2/genéticaRESUMEN
Trimethylamine N-oxide (TMAO), a common metabolite in animals and humans, can induce changes in the expression or conformation of heat shock proteins. It has also been introduced as a risk factor for atherosclerosis and a biomarker for kidney problems. On the other hand, increased levels of heat shock proteins 60 and 70 KDa are associated with increased atherosclerosis risk. This study was therefore designed to evaluate the possible effect(s) of TMAO on the expression of HSP60 and GRP78 at the mRNA and protein levels. Murine macrophage J774A.1 cells were treated with micromolar concentrations of TMAO and 4-phenylbutyric acid (4-PBA), a chemical chaperon, for different time intervals. Tunicamycin was also used as a control for induction of endoplasmic reticulum stress. Tunicamycin greatly increased both mRNA and protein levels of GRP78. Similarly but to a lesser extent compared to tunicamycin, TMAO also increased mRNA and protein levels of GRP78 in a dose and time-dependent manner. In contrast, 4-PBA failed to induce any changes. Similar to GRP78, HSP60 was also increased only at mRNA level in TMAO treated cells. 4-PBA also increased HSP60 mRNA levels, whereas, tunicamycin did not show any effect on either protein or mRNA levels of HSP60. Since both heat shock proteins are stress inducible and the elevation of GRP78 is a hallmark for endoplasmic reticulum stress induction, it can be concluded that TMAO may induce endoplasmic reticulum stress or may act through elevation of these heat shock proteins.