Cell Reports | GeneRulor Supports the Elucidation of a Microbiota–Metabolite–Host Axis in Gastric Cancer

In recent years, the role of intratumoral microbiota in cancer development has gained increasing attention. This study integrates

microbiomics, metabolomics, and classical molecular biology to delineate a complete “bacterium–metabolite–receptor–signaling pathway” oncogenic axis.

Gastric cancer ranks fifth globally in both incidence and mortality. While Helicobacter pylori is a well-established etiological factor,

clinical observations indicate that gastric cancer can still develop in H. pylori-negative patients or after successful eradication therapy,

suggesting the involvement of additional gastric microbiota.

S. anginosus, an opportunistic pathogen, has recently been found to be enriched in gastric cancer patients. However, whether it

contributes to tumor progression via metabolic products remained unclear.

1. Clinical Evidence: S. anginosus as a Prognostic Indicator

Analysis of gastric mucosal samples and tissue microarrays from patients with superficial gastritis, intestinal metaplasia, and gastric

cancer revealed a progressive increase in S. anginosus colonization.

High abundance of S. anginosus was significantly associated with advanced TNM stage and reduced overall survival, identifying it as

an independent prognostic risk factor.

2. Functional Validation: Both Bacteria and Their Metabolites Are Oncogenic

In vitro experiments showed that both S. anginosus infection and conditioned medium significantly promoted proliferation, migration, and invasion of gastric cancer cells while inhibiting apoptosis.

In the INS-GAS mouse model, oral administration of S. anginosus induced gastric inflammation and intestinal metaplasia.

These results indicate that both the bacterium and its secreted metabolites contribute to tumor-promoting effects.

3. Identification of the Key Metabolite: Succinate

Untargeted and targeted metabolomics analyses identified succinate as the most significantly enriched metabolite in S. anginosus

conditioned medium.

Elevated succinate levels were also detected in gastric cancer tissues, suggesting a strong association with disease progression.

4. [GeneRulor Contribution] Genetic Validation: Succinate Is Essential for Tumor Promotion

To establish causality, the study disrupted bacterial succinate biosynthesis.

GeneRulor constructed a metB knockout strain of S. anginosus via homologous recombination, where metB encodes a key enzyme

involved in succinate production.

These results unequivocally demonstrate that S. anginosus-derived succinate is required for its tumor-promoting function, providing   direct causal evidence.

5. Molecular Mechanism: Activation of the Succinate/SUCNR1/ABRAXAS1 Axis

The study further elucidated how succinate transduces signals into host cells:

• Succinate binds to its receptor SUCNR1 on gastric epithelial cells

• SUCNR1 recruits and interacts with ABRAXAS1

• This activates the downstream PI3K/AKT signaling pathwa

• Knockdown or pharmacological inhibition of SUCNR1 significantly abrogates tumor-promoting effects

Conditioned medium from S. anginosus accelerates gastric tumor progression in vitro and in vivo

This study systematically defines the “S. anginosus–succinate–SUCNR1–ABRAXAS1–PI3K/AKT”axis as a key driver of gastric cancer

progression.

It presents multiple translational opportunities:

• Biomarkers：S. anginosus abundance and succinate levels as diagnostic/prognostic indicators

• Therapeutic targets：SUCNR1 as a potential intervention target (inhibitor NF-56-EJ40 shows efficacy)

• Microbiome-based strategies：Targeting succinate-producing microbiota for cancer prevention

In microbiome–host interaction studies, correlation alone is insufficient; establishing causality is critical.

To definitively demonstrate that S. anginosus-derived succinate drives tumorigenesis,   the study   required genetic   disruption of   succinate   biosynthesis.

GeneRulor's microbial genome engineering platform enabled the construction of a metabolically deficient mutant (S. anginosus

ΔmetB), which played a decisive role.

• Precise Gene Knockout：

  Genetic manipulation of Streptococcus species is technically challenging. Using advanced homologous recombination and genome

  editing strategies, GeneRulor achieved precise, scarless deletion of the metB gene.

• Establishing a Complete Causal Framework：

  This“knockout–rescue”experimental design provides rigorous molecular evidence consistent with modern adaptations of Koch's   postulates.   Both in vitro and in vivo experiments (including Western blot pathway analysis and xenograft tumor models) demonstrated that replacing wild-type strains with the ΔmetB mutant significantly reduced PI3K/AKT activation and tumor growth.