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The aim of the current study is to examine the protective effect of MGN-3 on overall maintenance of hematopoietic tissue after γ-irradiation. MGN-3 is an arabinoxylan from rice bran that has been shown to be a powerful antioxidant and immune modulator. Swiss albino mice were treated with MGN-3 prior to irradiation and continued to receive MGN-3 for 1 or 4 weeks. Results were compared with mice that received radiation (5 Gy γ rays) only, MGN-3 (40 mg/kg) only and control mice (receiving neither radiation nor MGN-3). At 1 and 4 weeks post-irradiation, different hematological, histopathological and biochemical parameters were examined. Mice exposed to irradiation alone showed significant depression in their complete blood count (CBC) except for neutrophilia. Additionally, histopathological studies showed hypocellularity of their bone marrow, as well as a remarkable decrease in splenic weight/relative size and in number of megakaryocytes. In contrast, pre-treatment with MGN-3 resulted in protection against irradiation-induced damage to the CBC parameters associated with complete bone marrow cellularity, as well as protection of the aforementioned splenic changes. Furthermore, MGN-3 exerted antioxidative activity in whole-body irradiated mice, and provided protection from irradiation-induced loss of body and organ weight. In conclusion, MGN-3 has the potential to protect progenitor cells in the bone marrow, which suggests the possible use of MGN-3/Biobran as an adjuvant treatment to counteract the severe adverse side effects associated with radiation therapy.

In the current study, we investigated the chemopreventive activity of arabinoxylan rice bran, MGN-3/Biobran, against chemical induction of glandular stomach carcinogenesis in rats. Gastric cancer was induced by carcinogen methylnitronitrosoguanidine (MNNG), and rats received MNNG alone or MNNG plus Biobran (40 mg/kg body weight) for a total of 8 months. Averaged results from 2 separate readings showed that exposure to MNNG plus Biobran caused gastric dysplasia and cancer (adenocarcinoma) in 4.5/12 rats (9/24 readings, 37.5%), with 3.5/12 rats (7/24 readings, 29.2%) showing dysplasia and 1/12 rats (8.3%) developing adenocarcinoma. In contrast, in rats treated with MNNG alone, 8/10 (80%) developed dysplasia and adenocarcinoma, with 6/10 rats (60%) showing dysplasia and 2/10 rats (20%) developing adenocarcinoma. The effect of combining both agents was also associated with significant suppression of the expression of the tumor marker Ki-67 and remarkable induction in the apoptotic gastric cancer cells via mitochondrial-dependent pathway as indicated by the upregulation in p53 expression, Bax expression, downregulation in Bcl-2 expression, an increase in Bax/Bcl-2 ratio, and an activation of caspase-3. In addition, Biobran treatment induced cell-cycle arrest in the subG1 phase, where the hypodiploid cell population was markedly increased. Moreover, Biobran treatment protected rats against MNNG-induced significant decrease in lymphocyte levels. We conclude that Biobran provides protection against chemical induction of glandular stomach carcinogenesis in rats and may be useful for the treatment of human patients with gastric cancer.

This study was undertaken to evaluate the effectiveness and mechanisms of anti-tumor activity of Baker's yeast, Saccharomyces cerevisiae, in immunocompetent mice. Swiss albino mice were inoculated intramuscularly in the right thigh with Ehrlich Ascites Carcinoma (EAC) cells. At day 8, mice bearing Solid Ehrlich Carcinoma tumor (SEC) were intratumorally (IT) injected with killed S. cerevisiae (10 x 10(6) and 20 x 10(6) cells) for 35 days. Histopathology of yeast-treated mice showed extensive tumor degeneration, apoptosis, and ischemic (coagulative) and liquefactive necrosis. These changes are associated with a tumor growth curve that demonstrates a significant antitumor response that peaked at 35 days. Yeast treatment (20 x 10(6) cells) three times a week resulted in a significant decrease in tumor volume (TV) (67.1%, P < 0.01) as compared to PBS-treated mice. The effect was determined to be dependent on dose and frequency. Yeast administered three and two times per week induced significant decrease in TV as early as 9 and 25 days post-treatment, respectively. Administration of yeast significantly enhanced the recruitment of leukocytes, including macrophages, into the tumors and triggered apoptosis in SEC cells as determined by flow cytometry (78.6%, P < 0.01) at 20 x 10(6) cells, as compared to PBS-treated mice (42.6%). In addition, yeast treatment elevated TNF-alpha and IFN-gamma plasma levels and lowered the elevated IL-10 levels. No adverse side effects from the yeast treatment were observed, including feeding/drinking cycle and life activity patterns. Indeed, yeast-treated mice showed significant final body weight gain (+21.5%, P < 0.01) at day 35. These data may have clinical implications for the treatment of solid cancer with yeast, which is known to be safe for human consumption.

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