Comparison of Bacterial Phyla, Metabolites, and Apoptotic Pathways in the Intestinal Tissue of Colorectal Cancer Patients with Noncancerous

Abstract

Highly frequent and largely preventable colorectal cancer (CRC) is the third most common cancer worldwide. Tumor microenvironment (TME) bacteriome and metabolome are proposed to be involved in CRC development. It is controversial which bacteria and metabolites are associated with CRC. In this regard, we aimed to investigate the bacteriome, metabolome, and apoptotic pathways in the intestinal tissues of CRC patients and healthy individuals. Methods: Sixty tissue samples including healthy (H), adenomatous polyps (AP), adenomatous polyps-adjacent (APA), cancer tumor (CT), and cancer tumor-adjacent (CA) tissues were collected from age and sex-matched participants during the endoscopy procedure. 16S rRNA sequencing and 1H NMR spectroscopy were utilized to identify the bacteriome and metabolome. We also obtained total metabolites by anaerobic culture of tissues and treated HT-29 cells with these metabolites evaluating their apoptotic effect using MTT, real-time RT-PCR, and annexin V/PI binding staining assays. Results: We observed that the Lachnospiraceae family members depleted concomitant with acetoacetate and beta-hydroxybutyric acid accumulations in the AP tissues. In addition, several bacterial species including Gemella morbillorum, Morganella morganii, Parabacteroides johnsonii, Eikenella corrodens, Prevotella bivia, Lachnoclostridium symbiosum, and Hungatella effluvia were enriched in the AP group. Furthermore, acetate and fumarate were also accumulated concomitantly to Anaerotignum faecicola, Aeromonas enteropelogenes, Aeromonas veronii, and Fusobacterium nucleatum increased abundance in the CT group. We also observed that the viability of HT-29 cells was significantly reduced in a dose- and time-dependent manner after treatment with healthy individuals’ normal tissue metabolites (HINTM).