Anti-cancer and anti- genotoxic potential of Yoom Noon rice: induction of apoptosis, cell cycle arrest, and inhibiting migration and invasion in vitro

Yoom Noon, a strain of rice from the Royal Initiative of Southern Thailand, is rich in flavonoids and exhibits strong antioxidant properties. However, no research has yet been conducted on its anti-cancer properties, leading us to explore the activity of polished and unpolished Yoom Noon rice extracts against cancer cells. The main goal of this study was to evaluate the anti-cancer activity of polished and unpolished Yoom Noon rice extracts on colorectal cancer cells and their genotoxicity/anti-genotoxicity potential in lung fibroblast cells. In vitro assessments of the anti-cancer effects of Yoom Noon rice extracts on HCT116 and HT29 cells were carried out using MTS, trypan blue exclusion, clonogenic, wound healing and transwell migration assays. Annexin V/PI assay was used to study the induction of apoptosis. Cell cycle analysis was determined by flow cytometry. The genotoxicity and anti-genotoxicity were evaluated using cytokinesis-blocked micronucleus (MN) assay on V79 cells. Polished and unpolished Yoom Noon rice extracts clearly reduce the cellular viability of HCT116 with IC 50 at 48 h of 626.74 µg/mL and 736.85 µg/mL, respectively, while these extracts had IC 50 greater than 1000 µg/mL of HT29. The potent anti-proliferative ability of Yoom Noon rice extracts against HCT116 and HT29 cells was identified based on the self-renewal assay. These extracts at non-cytotoxic doses also significantly suppressed cancer migration and invasion of HCT116 cells. The cellular mechanism responsible for proliferative suppression demonstrated that treatment with Yoom Noon rice extracts increased apoptotic cell death of HCT116 and HT29 cells in a dose-dependent manner and arrest of HCT116 cells at the S phase. The micronucleus results showed that Yoom Noon rice extracts at concentrations of 250–750 µg/mL did not induce an increase in the number of micronuclei of V79 cells compared with the control after treatment for 24 h. Interestingly, treatment with different doses of Yoom Noon rice extracts concomitantly with Mitomycin C (MMC; a mutagen) led to a significant reduction in the frequency of micronucleated cells, when compared to the group treated only with MMC. Polished and unpolished Yoom Noon rice extracts exhibited anti-cancer and anti-genotoxic potential and did not induce genotoxicity in the in vitro test system.