Integrated culturomics and 16S rDNA sequencing reveal a functional microbiome signature in endometrial cancer

Endometrial cancer (EC) is a common gynecologic malignancy globally, but the role of the intratumoral microbiome remains poorly defined. While microbial dysbiosis is increasingly linked to cancer, the composition, function, and clinical relevance of the microbiota in EC are underexplored. This study aims to systematically profile the microbiome in EC patients by integrating culturomics and 16S rDNA sequencing, and to evaluate the functional properties of key bacterial strains in relation to tumor progression.

We collected cancerous tissues (CATs), non-cancerous adjacent tissues (NATs), and vaginal swabs from 32 EC patients. Culturomics was performed on 57 samples from 19 patients to isolate and identify bacteria, while 16S rDNA sequencing assessed microbial diversity and composition. Functional assays, including flow cytometry for invasion efficiency and ELISA, were used to evaluate pro-inflammatory capacity.

Culturomics identified 79 bacterial species, with Staphylococcus, Streptococcus, and Cutibacterium emerging as core genera shared across the vagina, NATs, and CATs. Functional analysis revealed that strains such as Staphylococcus epidermidis and Streptococcus anginosus exhibited high invasion efficiency (up to 84.8%) and significantly upregulated pro-inflammatory responses. 16S rDNA sequencing showed that Lactobacillus dominated the vaginal microbiota, whereas endometrial tissues were enriched with opportunistic pathogens (e.g., Stenotrophomonas). Critically, specific genera were associated with aggressive clinical features: Slackia with poorly differentiated (G3) tumors and Porphyromonas with deep myometrial invasion (≥ 50%).

This study uncovers a distinct, translocally disseminated core microbiota in EC, with key strains demonstrating invasive and pro-inflammatory capacities that may play a role in tumor progression. These findings provide a foundation for microbial biomarkers and targeted interventions, highlighting the transformative potential of microbiome research in gynecologic oncology.