The biodiversity Composition of Microbiome in Ovarian Carcinoma Patients Original paper

What was studied?

This study investigated the microbiome composition in ovarian carcinoma using 16S rRNA sequencing, focusing on its potential role as a microbial signature relevant to tumor biology and early detection. The analysis compared ovarian cancer tissues with normal distal fallopian tube tissues to determine whether specific microbial shifts—particularly involving Proteobacteria and Firmicutes—represent meaningful biomarkers for malignancy. The work also incorporated transcriptome sequencing to explore whether microbiome alterations interact with immune signaling pathways, positioning the ovarian cancer microbiome as a potential contributor to tumor-associated inflammation and immune dysregulation. This study directly supports microbial-signature database development by defining distinct taxonomic markers and altered microbial ratios associated with ovarian cancer.

Who was studied?

The study evaluated 25 women with high-grade serous ovarian cancer and 25 control participants providing normal distal fallopian tube tissue for discovery analysis, followed by an independent validation cohort of 46 cancer and 41 normal samples using qPCR confirmation. All participants were selected to minimize confounding microbial influences, such as recent antibiotic, probiotic, or prebiotic use, and those with active infections were excluded. Controls underwent salpingo-oophorectomy for benign uterine conditions, ensuring tissue availability but representing a limitation in defining true “healthy” upper reproductive tract microbiomes.

Most important findings

The cancer microbiome demonstrated reduced bacterial diversity, lower evenness, and distinct community structure relative to controls, confirmed through Shannon index reductions and principal coordinate analyses (PCoA). The most striking microbiome signature was a marked increase in Proteobacteria and a decrease in Firmicutes, shifting the Proteobacteria/Firmicutes ratio. LEfSe analysis identified cancer-associated enrichment of Acinetobacter, Sphingomonas, and Methylobacterium, with controls enriched in Lactococcus. At the species level, Acinetobacter lwoffii was significantly increased in cancer, while Lactococcus piscium showed high discriminatory performance with an AUC of 0.808 as illustrated in the validation ROC plots. Transcriptomic analysis revealed over 2,600 upregulated and 2,100 downregulated genes in cancer tissues. Pathway enrichment highlighted activation of NF-κB, cytokine–cytokine receptor, chemokine, Wnt, Hippo and p53 signaling pathways, suggesting inflammation-linked tumorigenic microenvironments potentially shaped by microbial dysbiosis. Antibacterial-response genes, including TLR and NOD receptor families, exhibited altered expression patterns consistent with immune disruption in tumor tissues.

Key implications

This study provides compelling evidence that the ovarian cancer microenvironment harbors a distinct dysbiotic microbiome, challenging assumptions that the upper reproductive tract is sterile. The enrichment of Proteobacteria—particularly Acinetobacter lwoffii—and depletion of beneficial taxa like Lactococcus piscium may represent early-stage microbial signals or contribute to chronic inflammation and immune modulation in carcinogenesis. These findings support the integration of ovarian cancer-associated microbiome signatures into clinical research frameworks and microbial biomarker databases, with L. piscium emerging as a promising candidate for diagnostic development. The interaction between dysbiosis and altered immune pathways highlights a plausible mechanism linking microbial imbalance to tumor progression and suggests an avenue for future microbial-targeted interventions.

Citation

Zhou B, Sun C, Huang J, et al. The biodiversity composition of microbiome in ovarian carcinoma patients. Scientific Reports. 2019;9:1691. doi:10.1038/s41598-018-38031-2