Decoding Bacterial Signatures in Gastric Cancer
Researchers at the University of Magallanes (UMAG) have uncovered distinct bacterial “signatures” within the stomach that evolve as patients transition from gastritis to gastric cancer. Published in Frontiers in Microbiology, the study leverages long-read nanopore sequencing to map the gastric microbiota of Chilean patients, providing a potential new framework for risk stratification and early clinical intervention.
The MAGIC Cohort and Nanopore Sequencing
A team from the Genómica Evolutiva y Médica en Magallanes (GEMMa) laboratory, including Dr. Yolanda Espinosa Parrilla and doctoral candidate Daniela Zapata Contreras, conducted the first characterization of the Chilean gastric microbiota using full-length 16S rRNA nanopore sequencing. Their study, “Microbial dynamics in gastric cancer: insights from full-length 16S rRNA nanopore sequencing in the MAGIC cohort,” examined 162 tissue samples from 83 patients.
These samples originated from the MAGIC cohort, a biorepository established in 2018 in partnership with the Hospital Clínico Magallanes, alongside the Biobanco de Tejidos y Fluidos de la Universidad de Chile (BTUCH). By observing bacterial communities across various stages of gastric pathology, the team sought to clarify why disease progression differs so sharply between individuals.
Microbial Succession During Disease Advancement
The gastric environment is remarkably fluid. While Helicobacter pylori acts as a primary driver during early inflammation, its relative abundance wanes as cancer advances.
“Our research allowed us to observe with an unprecedented level of detail how the structure of the bacteria that inhabit the stomach changes as the pathology progresses,” explained Daniela Zapata. As H. pylori recedes in later stages, it is replaced by genera including Lactobacillus, Limosilactobacillus, Clostridium, Streptococcus, Klebsiella, and Sarcina. These shifts form specific “bacterial signatures” that the authors propose could function as biomarkers for more precise risk assessment.
Addressing Geographic Gaps in Research
The data reveals differences in the gastric microbiome between patients in the Magallanes region and those in central Chile. Dr. Yolanda Espinosa Parrilla noted that most existing literature relies on Asian cohorts, making local data vital.
“For us, it was fundamental to generate knowledge of our own population in a region of such high incidence in gastric cancer as Magallanes,” Dr. Espinosa stated. Using long-read sequencing, the team achieved higher taxonomic resolution than conventional methods, clarifying how stomach pH and the microenvironment influence both bacterial communities and the development of the tumor microenvironment.
This study represents a significant advancement for Chilean science. By confirming that microbial composition fluctuates based on both disease stage and geography, the researchers highlight the urgent need to bolster local biological collections. Their work suggests that integrating these microbial signatures into clinical practice could eventually refine personalized prevention, offering clinicians a clearer view of the transition from benign lesions to malignancy.