REVIEW article
Front. Oncol.
Sec. Breast Cancer
Gut Microbiota-Regulated Tryptophan Metabolism in Breast Cancer: Mechanisms and Therapeutic Perspectives
Provisionally accepted
Jiaxi Yan1
Linfeng Qian1
Shiqi Chen1Maryam Mohammed Abbas Karekad2Xuanwei Wu1Musheng Xu3*
Xiaohong Xu4*- 1Zhejiang Chinese Medical University First Clinical Medical College, Hangzhou, China
- 2Zhejiang Chinese Medical University, Hangzhou, China
- 3Quzhou Hospital of Traditional Chinese Medicine, Quzhou, China
- 4Zhejiang Provincial Hospital of Chinese Medicine, Hangzhou, China
Select one of your emails
You have multiple emails registered with Frontiers:
Notify me on publication
Please enter your email address:
If you already have an account, please login
You don't have a Frontiers account ? You can register here
Breast cancer remains the most commonly diagnosed cancer among women worldwide, and multiple studies now link its development and progression to disturbances in metabolic and immune regulation. Among these factors, the gut microbiota is increasingly recognized as a modulator of host physiology through its metabolism of dietary tryptophan (Trp). Here we focus on the current understanding of the microbial metabolism of Trp, which primarily generates bioactive metabolites through the kynurenine (Kyn) pathway and the indole pathway. These metabolites can serve as endogenous ligands, activating the aryl hydrocarbon receptor (AhR) signaling pathway. They can also promote tumor stem cell characteristics, epithelial-mesenchymal transition (EMT), and metastasis via serotonin receptors (such as HTR1B/1D, HTR2B). The activation of such pathways contributes to the remodeling of the tumor immune microenvironment, alters the functions of immune cells, and directly influences the proliferation, invasion, and metastatic behavior of breast cancer cells. By integrating findings from preclinical and clinical studies, this review organizes current evidence around the "gut microbiota-Trp metabolism-breast cancer" axis and discusses clinical implications and current limitations. Targeting this metabolic network may provide new opportunities for breast cancer prevention and therapeutic intervention.
Keywords: Aryl hydrocarbon receptor, breast cancer, Gut Microbiota, kynurenine pathway, tryptophan metabolism, Tumor immune microenvironment
Received: 11 Dec 2025; Accepted: 09 Feb 2026.
Copyright: © 2026 Yan, Qian, Chen, Karekad, Wu, Xu and Xu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Musheng Xu
Xiaohong Xu
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.