Abstract 2872: E. coli-driven inflammatory and migratory responses in colorectal cancer and modulation by Bacillus coagulans

Abstract Background: Colorectal cancer (CRC) is one of the most diagnosed cancers in the United States and Puerto Rico, where survival remains lower than in the U.S. mainland. Puerto Rico has also reported a rising incidence of early-onset CRC (50 years), highlighting the need to clarify biological factors associated with risk. Microbial dysbiosis, particularly pathogenic Escherichia coli and inflammation, are recognized contributors to CRC, yet their relevance in CRC cohorts from Puerto Rico has not been fully explored. This study examined whether E. coli burden and inflammatory cytokines distinguish CRC cases from controls and evaluated whether the probiotic Bacillus coagulans modulates E. coli-induced invasive responses in CRC cell lines. Methods: Plasma and tissue samples from 15 age- and sex-matched CRC cases and controls from the Puerto Rico Familial Colorectal Cancer Registry (PURIFICAR) were analyzed. Plasma cytokines were quantified using the ProcartaPlex Inflammation Panel (Luminex), and tissue E. coli DNA abundance was measured by qPCR targeting the uidA gene. SW480 and SW620 colorectal cancer cell lines were cultured and stimulated with E. coli or recombinant MCP-1, with and without Bacillus coagulans co-treatment. Migratory capacity was evaluated using a wound-healing assay, capturing images at different time points and quantifying wound closure using ImageJ. Wilcoxon signed-rank exact tests were used for group comparisons, and ROC curve analyses evaluated diagnostic performance using univariable and multivariable models. All analyses were performed in R (version 4.4.1). Results: CRC cases showed higher tissue E. coli DNA abundance than controls (median 1.4 vs. 0.6; p 0.001). Among the plasma cytokines evaluated, only MCP-1 showed a significant difference, with higher levels in CRC cases than controls (median 112.1 vs. 57.5; p 0.001). A multivariable model combining MCP-1 and E. coli DNA yielded excellent diagnostic performance (AUC = 0.96; 95% CI: 0.91-1.00). In vitro, Bacillus coagulans reduced the migratory capacity of SW480 and SW620 cells when they were stimulated with E. coli or MCP-1. Conclusion: Our findings show that E. coli and MCP-1-related inflammation are linked to CRC in this cohort. The reduction in migration observed with Bacillus coagulans in vitro suggests a microbial immune interaction between the probiotic microorganism and CRC-associated tumor microenvironment. Citation Format: Sheila N. López Acevedo, Byron K. Olivo Natal, Camille Zenón Meléndez, Liliana Castro Jiménez, Hilmaris Centeno Girona, Elba V. Caraballo Rivera, . E. coli-driven inflammatory and migratory responses in colorectal cancer and modulation by Bacillus coagulans abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2872.