Effects of fucoxanthin on proliferation and apoptosis in human gastric adenocarcinoma MGC-803 cells via JAK/STAT signal pathway

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 (25 mu M, 50 mu M or 75 mu M). Data of flow cytometry revealed that fucoxanthin (50 mu M or 75 mu M) 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 (50 mu M or 75 mu M) significantly decreased the expressions of CyclinB1, survivin and STAT3 in MGC-803 cells in a dose-dependent manner both at the time of 24 h and 48 h. 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 (75 mu M) 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. (C) 2011 Elsevier B.V. All rights reserved.