Enhancing the Apoptotic Effect of a Low Dose of Paclitaxel on Tumor Cells in Mice by Arabinoxylan Rice Bran (MGN-3/Biobran)*

In this study, we examine the ability of arabinoxylan rice bran (MGN-3/Biobran) to enhance the apoptotic effect of paclitaxel (Taxol) at low concentration [2 mg/kg body weight (BW)] in animals bearing Ehrlich ascites carcinoma (EAC) cells and elucidate its mechanisms of action. On Day 8 following tumor cells inoculation, mice bearing tumors were administered MGN-3 alone (40 mg/kg BW), paclitaxel alone, or MGN-3 plus paclitaxel. On Day 30 post-tumor inoculation, we observed significant suppression of tumor volume (TV) with paclitaxel alone (59%), MGN-3 alone (77%), and MGN-3 plus paclitaxel (88%). Inhibition of tumor growth post-treatment with both agents, as compared with either treatment alone, was associated with a decrease in cell proliferation, a marked increase in the sub-G0/G1 population, an increase in DNA damage and apoptosis of tumor cells, and a significant maximization of the apoptosis index (AI)/proliferation index (PrI) ratio. Histopathological and electron microscopy examination of the combined treatment group showed an increase in the degenerative regions of the solid tumor tissue and abundant apoptotic cells. These data suggest that MGN-3 supplementation enhances tumor cell demise in the presence of a low dose of chemotherapeutic agent via apoptotic mechanism.