Effect of GABA-rich rice bran fermented by <i>Lactobacillus fermentum</i> on breast cancer cell growth

Gamma-aminobutyric acid (GABA), a non-protein amino acid widely distributed in several natural products, exhibits potential for regulation of various cancers. The aim of this study was to examine the suppressive effect of GABA-containing product (GCP) derived from <i>Lactobacillus fermentum</i>-fermented rice bran on MCF-7 cell breast cancer cells. The MTT assay was used to measure cytotoxicity following exposure to GCP. Further, qPCR analysis was utilized for assessment of target gene expression, while flow cytometry was employed for determination of apoptosis and cell cycle arrest. Data demonstrated that GCP significantly suppressed migration of MCF-7 breast cancer cells at a non-cytotoxic concentration of 400 µg/ml. In addition, GCP downregulated the gene and protein expression of matrix metalloproteinase (MMP)-2 and -9 in these cells. Notably, treatment of GCP produced cell cycle arrest in phase of G2/M and induced an early apoptotic process via upregulation of caspase-8, -9, and Bax expression. Evidence indicates that GCP may be considered as a promising food ingredient for management of breast cancer metastasis.