The Effect of Anthocyanins Black Rice Bran Extract (ABRiBE) on Colorectal Cancer Cell Proliferation and ABCA1 Gene Expression in the HT-29 Cell Line

Background: Anthocyanins inhibit colorectal cancer cell proliferation and cholesterol levels regulation by interacting with the adenosine triphosphate-binding cassette subfamily A member 1 (ABCA1) protein, expressed at reduced levels in colon cancer. Anthocyanins can also increase the efflux of cholesterol from cancer cells and are present in Indonesian native black rice bran. Therefore, this study investigated the effect of Anthocyanin Black Rice Bran Extract (ABRiBE) on the mRNA expression of the ABCA1 gene and the proliferation of colorectal cancer cells in the human HT-29 cell line. The hypothesis is that ABRiBE inhibits HT-29 cell proliferation and increases ABCA1 gene expression. Methods: This experimental study on the HT-29 cells used anthocyanins extracted from black rice bran powder through ethanol acidified with citric acid. The MTS assay measured the inhibitory concentration (IC₅₀) of 50% cell proliferation inhibition using 12 extract concentrations and control groups for 24 and 48 hours. The ABCA1 gene expression in groups above the antiproliferative IC50 value and the control group was analyzed using the quantitative Polymerase Chain Reaction (qPCR) method. Results: The IC₅₀ of black rice bran extract was 1.57 and 1.35 mg/mL for 24 and 48 hours of incubation, which decreased HT-29 cell proliferation with values of (r=0.97, p=0.001 and r=0.95, p=0.001), respectively. Extract exposure of the 2 concentrations above the IC₅₀ values of 1.7 and 2.0 mg/mL increased ABCA1 gene expression in HT-29 cells, by 1.16 and 2.32 fold compared to the control group. Conclusion: The ABRiBE inhibited HT-29 cell proliferation and increased the ABCA1 gene expression.