RED RICE BRAN EXTRACT SUPPRESSES COLON CANCER CELLS VIA APOPTOSIS INDUCTION/CELL CYCLE ARREST AND EXERTS ANTIMUTAGENIC ACTIVITY.

BACKGROUND: Red rice bran extract (RRBE) contains many biologically active substances exerting antioxidant and anti-inflammatory effects. AIM: To evaluate the anticancer potential of RRBE in human colon cancer cells and its mutagenic/antimutagenic effects on nonmalignant cells. MATERIALS AND METHODS: The cytotoxic effect of RRBE was determined by trypan blue exclusion in HCT116, HT29 cell lines and a non-cancerous HEK293 cell line, and its antiproliferative effect using MTS and colony formation assay. The apoptosis induction was evaluated using ELISA, and the apoptotic rate and cell cycle progression were assessed by flow cytometry. The mutagenic/ antimutagenic potential of RRBE was analyzed by micronucleus assay in the V79 cell line. RESULTS: RRBE caused a dose-dependent reduction of cell viability in colon cancer cells and showed a limited cytotoxicity against HEK293 cells. The treatment with RRBE suppressed proliferation of HCT116 and HT29 cells and induced apoptosis as evidenced by the increased DNA fragmentation and the apoptotic cell counts. Furthermore, RRBE treatment significantly increased the number of cells at the G2/M phase triggering the arrest of the cell cycle in colon cancer cells. Interestingly, RRBE did not increase the micronucleus frequency in V79 cells but reduced the micronucleus formation caused by mitomycin C. CONCLUSION: RRBE effectively suppressed proliferation, induced apoptosis, and caused a cell cycle arrest in human colon cancer cells while being non-mutagenic and exerting antimutagenic effects in vitro.

Anticancer and Antimutagenic Properties of Pogonatherum paniceum on Colorectal Cancer Cells.

Background: Pogonatherum paniceum (P. paniceum) (Lam.) Hack. plays an important role in detoxification. However, its anticancer activity has not yet been elucidated. The aim of our study was to examine the suppressive proliferation, anti-migration and mutagenic/antimutagenic properties of P. paniceum. Moreover, we set out to determine the cellular mechanism underlying its antiproliferation. Methods: To investigate P. paniceum's anticancer ability, HCT116 and HT29 cell lines were treated with a water extract containing P. paniceum, and then the cell viability was examined using the trypan blue exclusion method which were compared to HEK293 (non-cancerous cells). The anticancer effects were investigated by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) and colony formation assay. Apoptosis induction, cell cycle distribution, and migration abilities were assessed by cell death detection enzyme-linked immunoassay (ELISA), flow cytometry, and wound healing assay. Finally, the mutagenicity and antimutagenicity were evaluated using the micronucleus assay. Results: Treatment with P. paniceum caused a loss of cell viability in HCT116 and HT29 cells (not found in HEK293), which had an IC50 (half-maximal inhibitory concentration) of 1,156.2 and 1,207.0 µg/mL, respectively. We found that P. paniceum significantly inhibited the proliferative function of HCT116 and HT29 cells. To find the mechanism that exerts a suppressive proliferation effect on P. paniceum, we determined the DNA fragmentation and cell cycle distribution. We also found that P. paniceum treatment increased apoptosis and arrested of the cell cycle at G0/G1 remarkably when compared with the control group. Moreover, P. paniceum could decrease the migration of HCT116 and HT29 cancer cells. Finally, the treatment of P. paniceum did not induce micronucleus formation but did decrease the micronucleus frequency against mutagen-mitomycin C. Conclusions: P. paniceum did not possess any toxicity (cytotoxic and mutagenic) but has the potential for anticancer activity against human colorectal cells by increasing apoptosis, which leads to the suppression of cell proliferation. P. paniceum also inhibits cell migration and exerts antimutagenicity, thereby suggesting that P. paniceum might be useful for colorectal cancer treatment.