MicroRNA Analysis in Normal Human Oral Keratinocytes and YD-38 Human Oral Cancer Cells

MicroRNAs (miRNAs) are small non-coding RNAs that mediate gene expression at the post-transcriptional level by degrading or repressing targeted mRNAs. These molecules are about 21-25 nucleotides in length and exert their effects by binding to partially complementary sites in mRNAs, predominantly in the 3'-untranslated region (3'-UTR). Recent evidence has demonstrated that miRNAs can function as oncogenes or tumor suppressors through the modulation of multiple oncogenic cellular processes in cancer development, including initiation, cell proliferation, apoptosis, invasion and metastasis. In our present study, we examined the expression profile of miRNAs related to oral cancer cell growth inhibition using normal human oral keratinocytes (NHOK) and YD-38 human oral cancer cells. By miRNA microassay analysis, 40 and 31 miRNAs among the 1,769 examined were found to be up- and down-regulated in YD-38 cells compared with NHOK cells, respectively. Using qRT-PCR analysis, the expression levels of miR-30a and miR-1246 were found to be increased in YD-38 cells compared with NHOK cells, whereas miR-203 and miR-125a were observed to be decreased. Importantly, the overexpression of miR-203 and miR-125a significantly inhibited the growth of YD-38 cells. This finding and the microarray data indicate the involvement of specific miRNAs in the development and progression of oral cancer.

Cytotoxicity on Human Cancer Cells and Antitumorigenesis of Chungkookjang, a Fermented Soybean Product, in DMBA-Treated Rats

It is reported that a fermented soybean food, Doenjang, has strong antimutagenic and cytotoxic effect on cancer cells. This study investigated the effect of Chungkookjang, another traditional popular Korean soybean fermented food, on growth of cancer cells: HL-60, SNU-638 and MCF-7, and also its in vivo antitumorigenic effect in DMBA-induced mammary tumor rat model. For the in vitro study, Chungkookjang and steamed soybeans were extracted with ethanol and sequentially fractioned with 5 kinds of solvents differing in grades of polarity such as hexane, dichloromethane, ethylacetate, butanol and water. Almost all Chungkookjang extracts significantly inhibited the growth of HL-60 (human leukemic cancer cell), SNU-638 (human gastric cancer cell) and MCF-7 (human breast cancer cell) when compared to steamed soybean extracts. Butanol fraction of Chungkookjang extract especially showed a remarkable inhibitory effect in all the three kinds of cancer cells. To induce a mammary gland tumor, DMBA (50 mg/BW) was administered to 50 day-old female rats and followed by Chungkookjang or steamed soybean supplemented diets. Freezedried Chungkookjang powder (20% of diet in wet weight) was added to AIN-93G based diet for the Chungkookjang group of rats. Likewise, steamed soybean powder containing equal protein content to that of Chungkookjang powder was supplemented to soybean group of rats. At 13 weeks later, the mammary tumor incidence, average tumor number and tumor weight a rat were lower in Chungkookjang group compared to the control or soybean group. In conclusion, Chungkookjang showed a strong inhibitory effect on cancer cell growth in vitro, as well as a more preventive effect against chemically induced mammary tumorigenesis in vivo, while steamed soybeans did not. Therefore, these results suggest that Chungkookjang acquire its anticancer activity through the fermentation process.

Prevention of coronary heart disease and cancer by tea, a review

Biomedical research has uncovered the mechanisms whereby tea promotes good health and lowers the risk of major chronic diseases, such as heart disease and many types of cancer. The active components in tea are polyphenols, epigallocatechin gallate in green tea, theaflavins and thearubigins in black tea. Green and black tea and the polyphenols have similar beneficial effects. The mechanisms are categorized into 5 groups. 1) Tea polyphenols are powerful antioxidants. They decrease the oxidation of LDL cholesterol and lower the risk of heart disease, and also inhibit action of reactive oxygen species mediating the oxidation of DNA associated with carcinogenesis 2) Tea polyphenols induce detoxifying enzymes, glucuronosyl transferases, eliminating active forms of carcinogens and other toxicants, accounting for the lower cancer risk. 3) Tea polyphenols lower duplication rates of cancer cells and inhibit the growth of cancer, increase apoptosis and lower angiogenesis. 4) Tea polyphenols alter the intestinal bacterial flora, suppressing undesirable bacteria and favoring growth of beneficial bacteria. 5) Aging phenomena, and diseases associated with the formation of reactive oxygen species (ROS) are inhibited.