Microbiota in Tumors: Is it a New Hope for Treatment?

Increasing evidence suggests that the human microbiota plays a pivotal role in immune function, metabolism, and tumor progression. Recent studies have revealed that alterations in the gut microbiota composition can impact the efficacy and side effects of cancer therapies, including chemotherapy, immunotherapy, and radiation therapy. Some evidence has been provided for the existence of intratumoral microbiota and suggested that regulating intratumoral microbiota may affect tumor metastasis and drug resistance. Tumor bacterial peptides, in particular, have emerged as promising targets for cancer immunotherapy, demonstrating the ability to modify responses to immune checkpoint inhibitors. Consistent with this, tumor areas harboring bacterial colonization exhibit a pronounced immunosuppressive environment characterized by diminished presence of cytotoxic T cells compared to other tumor areas. Moreover, tumor areas in proximity to bacteria display upregulated expression of immune checkpoint proteins, which hinder the anti-tumor activity of T cells. However, recent studies have also raised doubts about the presence of intratumoral microbiota and have refuted some previous research findings. Overall, intratumoral microbiota may potentially exist and interact with the tumor microenvironment and influence tumor progression. The gut microbiota can exert systemic effects on health and immune responses through diverse metabolic products.

This Research Topic aims to assemble Original Research, Reviews, and Methods for identifying the changes in gut/ intratumoral microbiota occurring in different tumors, deciphering the mechanisms by which these microbiota influence tumor progression and treatment response, and exploring novel targets and strategies for tumor therapy based on microbiota.

Specific areas to cover include, but are not limited to:
1. Exploring the specific alterations in the gut/intratumoral microbiota of patients with tumors, as well as their potential role as clinical biomarkers;
2. The relationship between tumor cells and microbiota, elucidated through genetic and epigenetic assays;
3. The role of gut/intratumoral microbiota in the response and toxicity to cancer therapy, especially immunotherapy;
4. The influences of microorganisms on tumor progression and tumor microenvironments, through in vitro or in vivo models;
5. Studies focused on novel technologies and methodologies pertaining to tumor-associated microorganisms, including but not limited to innovative bioinformatics algorithms, software tools, and experimental models;
6. The impact of microbiota on tumor-related diseases, such as tumor-related heart disease.
7. Any studies that discuss the presence or absence of intratumoral microbiota, including reanalysis of previous findings and proposing new perspectives.