RESUMEN
Fucoxanthin is a natural carotenoid that had never been previously demonstrated to have anti-tumor effect on human gastric adenocarcinoma SGC-7901 or BGC-823 cells. Here it was found to inhibit proliferation and induce apoptosis through JAK/STAT signal pathway in these cells; the mechanism by which this occurred was investigated. We find that fucoxanthin significantly increased the number of apoptotic cells by propidium iodide (PI) dye staining and flow cytometry. Fucoxanthin (50 or 75 µM) induced SGC-7901 cells cycle arrest at S phase, while BGC-823 cells arrest at G2/M phase. RT-PCR and western blot analysis revealed that the expressions of Mcl-1, STAT3 and p-STAT3 were obviously decreased by fucoxanthin in a dose-dependent manner. Synthetic siRNA targeting Mcl-1 was transfected into cells which had no effect on expressions of STAT3. After pretreatment with AG490 (50 µM) which led to blocking of the JAK/STAT signal pathway, the reductive expressions of Mcl-1, STAT3 and p-STAT3 caused by fucoxanthin were inhibited. This is the first analysis of effects on SGC-7901 and BGC-823 cells by fucoxanthin. Fucoxanthin can induce cell-cycle arrest and apoptosis in these cells. These effects involved downregulation of Mcl-1, STAT3 and p-STAT3. This work is significant for better understanding of mechanisms leading to human gastric adenocarcinoma formation and informing exploitation of anti-tumor marine drug, and for providing Mcl-1 and STAT3 as potential therapeutic targets for gastric adenocarcinoma.
Asunto(s)
Adenocarcinoma/genética , Adenocarcinoma/patología , Antineoplásicos , Proliferación Celular/efectos de los fármacos , Proliferación Celular/genética , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/genética , Proteína 1 de la Secuencia de Leucemia de Células Mieloides/genética , Proteína 1 de la Secuencia de Leucemia de Células Mieloides/fisiología , Factor de Transcripción STAT3/genética , Factor de Transcripción STAT3/fisiología , Neoplasias Gástricas/genética , Neoplasias Gástricas/patología , Xantófilas/farmacología , Apoptosis/genética , Puntos de Control del Ciclo Celular/efectos de los fármacos , Puntos de Control del Ciclo Celular/genética , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Humanos , Phaeophyceae , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Transducción de Señal/fisiologíaRESUMEN
In this study, we investigated the anti-tumor effects and possible mechanisms of fucoxanthin, which has been reported to inhibit tumor proliferation and induce apoptosis in vitro or in vivo. Human gastric adenocarcinoma MGC-803 cells were treated with fucoxanthin (25µM, 50µM or 75µM). Data of flow cytometry revealed that fucoxanthin (50µM or 75µM) increased the ratio of cell in G2/M phase and apoptotic MGC-803 cells varying on a dose-dependent manner. Results from reverse transcriptase-polymerase chain reaction and Western blot showed that treatment with fucoxanthin (50µM or 75µM) significantly decreased the expressions of CyclinB1, survivin and STAT3 in MGC-803 cells in a dose-dependent manner both at the time of 24h and 48h. In addition, immunofluorescence microscopy analysis also revealed the suppressed expressions of CyclinB1 and survivin by fucoxanthin. After pretreatment with AG490 (the inhibitor for JAK/STAT signal pathway), the expressions of p-STAT3 and survivin remained also slightly lower than the vehicle control group. Co-treated with fucoxanthin (75µM) and AG490, the reduction on the expressions of STAT3, p-STAT3 and CyclinB1 by fucoxanthin were attenuated while that of survivin was enhanced. Taken together, fucoxanthin can down-regulate the expressions of CyclinB1 and survivin, inducing cell cycle arrest in G2/M phase, and apoptosis in MGC-803 cells. The reduction of CyclinB1 by fucoxanthin was associated with JAK/STAT signal pathway.