The role of the microbiome in ovarian cancer: mechanistic insights into oncobiosis and to bacterial metabolite signaling Original paper

What was studied?

This review focuses on the role of the microbiome in ovarian cancer, specifically its influence on inflammation, immune modulation, and carcinogenesis. The study highlights the concept of “oncobiosis,” a term used to describe microbial dysbiosis associated with cancer. It explores how specific bacterial communities in ovarian cancer tissue, the genital tract, peritoneum, and even serum, contribute to cancer progression. The paper also investigates bacterial metabolites, such as lipopolysaccharides (LPS), lysophospholipids, and tryptophan derivatives, and their roles in promoting inflammation and tumor development. Additionally, the interaction between the microbiome and ovarian cancer therapies, like chemotherapy, is examined, suggesting that microbiome manipulation may influence therapeutic outcomes.

Who was studied?

The review includes research on ovarian cancer patients, with data from various microbiome compartments such as the vaginal, cervicovaginal, peritoneal, and gastrointestinal tracts. Studies involving both human samples and animal models were referenced to explore microbial composition in ovarian cancer patients compared to healthy controls. It also considers the impact of infections such as Chlamydia trachomatis and Neisseria gonorrhoeae, which are linked to increased ovarian cancer risk. Furthermore, the paper discusses the use of antibiotics and probiotics in modulating the microbiome to potentially influence ovarian cancer progression and treatment responses.

Most important findings

The review identifies significant microbial shifts associated with ovarian cancer. In ovarian cancer tissues, there is an increase in Gram-negative bacteria, such as Proteobacteria and Fusobacteria, which are known for their inflammatory properties. Dysbiosis is also evident in other compartments, such as the vaginal and peritoneal microbiomes, where reduced diversity and an increase in pathogenic bacteria were observed. The review further highlights the involvement of microbial metabolites in carcinogenesis, including lipopolysaccharides (LPS), which trigger inflammatory pathways through TLR4 receptors, and lysophospholipids, which promote cancer cell migration and invasion. Tryptophan metabolites, particularly indole derivatives, are also implicated in ovarian cancer progression. The paper suggests that microbial metabolites may influence chemotherapy effectiveness, with some bacterial species enhancing drug resistance while others may reduce tumor proliferation.

Key implications

This review underscores the potential of microbiome-based interventions in ovarian cancer management. It suggests that modulating the microbiome, through antibiotics, probiotics, or diet, could influence inflammation and immune responses, thereby improving treatment outcomes. Given the microbiome’s role in promoting carcinogenesis, targeting specific bacterial populations or their metabolites may provide novel therapeutic avenues. Additionally, understanding microbiome signatures could assist in early diagnosis, monitoring disease progression, and predicting treatment responses. However, the review emphasizes that more research is needed to fully understand the complex interactions between the microbiome and ovarian cancer, and to refine microbiome-based treatments for clinical use.