In this stduy, we investigated preventive effects of black soybean doenjang on colitis-associated cancer in vitro and in vivo. In vitro preventive effects of black soybean doenjang on HT-29 human colon cancer cells were studied. SD (soybean doenjang prepared using nine-time baked bamboo salt), and BD (black soybean deonjang prepared using nine-time baked bamboo salt) were compared to CD (commercial doenjang). There were no significant differences between experimental groups in pH, amino type nitrogen, and ammonia type nitrogen levels of the doenjang samples. BD showed the highest antioxidative effect, followed by CD and SD in order. BD showed the highest total polyphenol concentration. CD, SD and BD extracts had no toxic effects within the range of 0.1 mg/mL ~ 0.5 mg/mL in normal RAW 264.7 cells. BD showed the highest preventive effect on the HT-29 as determined by MTT assay, and the BD regulated cancer-related genes in mRNA expression.
In vitro synergistic preventive effects of black soybean doenjang and 5-FU on HT-29 human colon cancer cells were studied. BD and 5-FU showed preventive effects of colon cancer in the HT-29 as determined by MTT assay. BD and 5-FU mixed at different concentrations showed synergistic preventive effect on colon cancer in the HT-29 as determined by MTT assay and RT-PCR.
Colon cancer was induced by 10 mg/kg Azoxymethane (AOM) / 2% dextran sulfate sodium (DSS) in male C57BL/6J mice. Animals were divided into five groups: Normal (no treatment), Control (AOM/DSS treated group), CD (commerical doenjang with AOM/DSS treated group), SD (soybean doenjang with AOM/DSS treated group), and BD (black bean doenjang with AOM/DSS treated group). First experiment was performed by adding sample into a diet. The length of colon was shortened in mice in control group. Administration of sample group increased colon length, and decreased colon weigth/length ratio. BD decreased histological colon injury of the AOM/DSS-induced colon cancer. SD and BD suppressed colon cancer markers in AOM/DSS-treated colon tissues that is related with inflammation; in serum and mRNA expression.
Second experiment was performed by oral adminstration (2g/kg). The length of colon was shortened in mice in control group. Administration of CD, SD, and BD increased colon length, and decreased colon weigth/length ratio, tumor number and spleen weight. Histological observation showed that SD and BD significantly decreased colon injury of the AOM/DSS induced colon cancer. CD, SD and BD regulated colon cancer markers; not only the inflammation related genes in serum, but also the mRNA expressions of inflammation related, cell cycle arrest and apoptosis related genes in AOM/DSS-treated colon tissues. In sample groups, BD was more regulated colon cancer expression than other groups because of clinical observation, histological observation, ELISA and RT-PCR experiments.
From the results above, BD exhibited the highest preventive effects by inhibiting growth of the HT-29 cells, alleviating symptoms of AOM/DSS-induced colon cancer, regulating pro-inflammatory cytokines and cell cycle-related genes. These results might be due to use of black soybean that contains high levels of polyphenol incluing anthocyanins.