Abstract 1830: Phenylacetaldehyde induces apoptosis through endoplasmic reticulum and potentiates the effect of 5-FU treatment in colorectal cancer cells

Abstract Introduction: Phenylacetaldehyde (PAA), a product of phenylalanine metabolism, is generated by microbiota and has demonstrated anticancer properties in breast cancer. As the gut microbiome influences intestinal homeostasis, we investigated the effects of PAA on colorectal cancer (CRC). Methods: Serum PAA levels and feces microbiota from 30 CRC patients and 30 healthy controls were analyzed by targeted GC-MS/MS and metagenomic sequencing. A validation cohort of 75 CRC patients and 53 healthy controls was analyzed for PAA level in serum. CRC cell lines and CRC-patient derived organoids were cultured and treated with PAA alone and in combination with 5-fluouracil (5-FU, standard chemotherapy used for CRC), then evaluated for viability, proliferation, cell cycle distribution, and cell death in vitro. We interrogated the mechanistic pathways induced by PAA treatment using RNA sequencing and western blot. Results: PAA levels were significantly decreased in the circulation of CRC patients compared to healthy controls in our study population and the validation cohort. Metagenomic sequencing indicated the bacteria that positively correlated with PAA levels were significantly more abundant in healthy controls; while bacteria that negatively correlated with PAA were more abundant in CRC. In vitro, PAA inhibited the viability and colony formation of CRC cell lines as well as human-derived organoids in a concentration-dependent manner. Mechanistically, PAA treatment induced a P53-dependant G1 cell cycle arrest and cell death in HCT116 and RKO cell lines. Proteomic analysis also demonstrated a downregulation in PI3K/AKT/mTOR and ERK pathways. Investigation by RNA sequencing showed that PAA inhibits CRC by inducing endoplasmic reticulum stress-induced autophagy. When combined with 5-FU, PAA enhanced the potency of 5-FU on viability, cell death, and cell cycle arrest by inducing DNA damage. Conclusions:The bacteria metabolite PAA increased CRC cell death by endoplasmic reticulum stress-induced autophagy and downregulation of the PI3K/AKT/mTOR and ERK pathways. PAA also potentiated chemotherapeutic efficacy of 5-FU through induction of DNA damages. These findings warrant further exploration of PAA as a potential CRC biomarker and novel therapeutic agent. Citation Format: Sylvain Ferrandon, Cheng Kong, Joseph Fedro, Rami-James Aoun, Chureeporn Chitchumroonchokchai, Steven Clinton, Matthew F. Kalady. Phenylacetaldehyde induces apoptosis through endoplasmic reticulum and potentiates the effect of 5-FU treatment in colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1830.