The inhibitory effects of the novel Lactobacillus cocktail on colorectal cancer development through modulating BMP signaling pathway: In vitro and in vivo study

This study investigates the impact of a five-strain <i>Lactobacillus</i> cocktail (comprising two strains of <i>L. plantarum</i>, and one strain each of <i>L. brevis</i>, <i>L. reuteri</i>, and <i>L. rhamnosus</i>) on colorectal cancer (CRC) modulation by targeting the bone morphogenetic proteins (BMP) signaling pathway. Both <i>in vitro</i> and <i>in vivo</i> (models were employed. The antiproliferative effects of the <i>Lactobacillus</i> cocktail on HT-29 cells were assessed via the MTT assay. Mice were divided into three groups: a negative control (treated with PBS), a positive control (treated with azoxymethane (AOM)/dextran sulfate sodium (DSS) + PBS), and a test group (treated with AOM/DSS + <i>Lactobacillus</i> cocktail in PBS). The role of the <i>Lactobacillus</i> cocktail in inhibiting the BMP signaling pathway was evaluated using qRT-PCR for gene expression analysis and western blotting for β-catenin protein assessment in both models. The MTT assay results demonstrated a significant, time-dependent reduction in HT-29 cell proliferation. qRT-PCR indicated downregulation of the BMP signaling pathway in treated cells, which subsequently led to decreased expression of the hes1 gene, crucial for cell differentiation and proliferation control. This inhibitory effect was corroborated in the mice model, showing significant downregulation of BMP pathway genes and <i>hes1</i> in the AOM/DSS/<i>Lactobacillus</i> cocktail-treated group. Additionally, western blotting revealed a marked decrease in β-catenin expression in both <i>in vitro</i> and <i>in vivo</i> experiments. Collectively, these findings suggest that the <i>Lactobacillus</i> cocktail may aid in CRC prevention by downregulating the BMP signaling pathway.