Characterization of the Anti-Cancer Activity of the Probiotic Bacterium Lactobacillus fermentum Using 2D vs. 3D Culture in Colorectal Cancer Cells

The aim of this study was to investigate the potential anti-cancer effects of probiotic cell-free supernatant (CFS) treatment using Lactobacillus fermentum for colorectal cancer (CRC) in 3D culture systems. Cell viability was assessed using MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) assays, whereas apoptosis was monitored through RT-qPCR analysis of Bax, Bak, Noxa, and Bid mRNA expressions in addition to flow cytometry analysis of Lactobacillus cell-free supernatant (LCFS) treatment. Our results showed that the anti-cancer effect of LCFS on cell viability was pronouncedly enhanced in 3D-cultured HCT-116 cells, which was linked to the increased level of cleaved caspase 3. Additionally, upregulation of apoptotic marker gene mRNA transcription was dramatically increased in 3D cultured cells compared to 2D systems. In conclusion, this study suggests that LCFS enhances the activation of intrinsic apoptosis in HCT-116 cells and the potential anti-cancer effects of Lactobacilli mixtures in 3D culture systems. All in all, our study highlights the benefits of 3D culture models over 2D culture modeling in studying the anti-cancer effects of probiotics.