The Dual Role of the Gut Microbiota in Cancer Chemoresistance.

Chemoresistance is one of the primary reasons that cancer chemotherapy fails to deliver successful treatment outcomes and contributes to poor overall survival rates for patients with cancer. New research has begun to shed light on the effects of the gut microbiome (GM). This new research will examine how certain microorganisms (referred to as "bad bacteria") can contribute to cancer treatment failure, as well as how others (such as Bifidobacterium, Akkermansia, and Lactobacillus) can enhance treatment success. This review will focus on the molecular mechanisms underlying these effects, including drug metabolism by microorganisms, modulation of the immune system by microorganisms, regulation of cellular apoptosis by microorganisms, and metabolic crosstalk between tumor tissue and the microbiome. Finally, we will look at new therapies under development that leverage knowledge of the microbiome to combat chemoresistance, including fecal microbiota transplantation, targeted probiotic and prebiotic supplementation, and dietary modifications. By studying the complex interactions among the host, the microbiome, and chemotherapeutic agents, we hope to demonstrate how microbiome-centered approaches can tailor and enhance an individual's cancer treatment while transforming the GM from a passive participant to an active target in cancer therapy.