Gut Bacteria’s Double-Edged Sword: Metabolites Found to Both Fuel and Fight Cell Growth
A groundbreaking new study reveals that molecules produced by gut bacteria can dramatically influence cell growth, offering potential avenues for cancer therapies and autoimmune disease prevention. Researchers at the University of Chicago have identified two key metabolites – queuine and pre-queuosine 1 (preQ1) – that compete to control the cellular machinery responsible for building proteins.
The Microbiome’s Unexpected Reach
The trillions of bacteria, viruses, and fungi residing within the human body, collectively known as the microbiome, are increasingly recognized for their profound impact on health. Beyond providing essential micronutrients, these microorganisms appear capable of directly influencing cellular processes at a fundamental level. This latest research, published in Nature Cell Biology in February 2025, demonstrates just how deeply this influence extends.
Decoding the Cellular Language
Within every cell, transfer RNAs (tRNAs) act as crucial translators, reading genetic code and assembling proteins, one amino acid at a time. These tRNAs are often chemically modified to optimize their function. Disruptions to these modifications can contribute to serious health issues, including cancer and neurological disorders.
One of the most complex tRNA modifications is the addition of queuosine (Q). Human cells cannot produce queuosine independently and rely on dietary intake or gut bacteria to provide queuine, a building block for this vital modification. Q-modified tRNAs enhance the efficiency and accuracy of ribosomes, the cellular factories responsible for protein synthesis, particularly under stressful conditions.
A Tale of Two Metabolites
Queuine is created through an eight-step process within bacteria. An intermediate product of this process is preQ1, which is consistently present in bacterial cells and released into the gut as bacteria die. Researchers discovered that queuine and preQ1 have opposing effects on cell growth.
“It is remarkable to see how the two bacterial metabolites can reprogram fundamental processes like translation in opposing ways inside our own cells to dictate cell growth,” explained a senior author of the study, Tao Pan, PhD, Professor of Biochemistry and Molecular Biology and the Committee on Microbiology at the University of Chicago.
PreQ1: A Potential Cancer Therapy?
Experiments conducted on mice revealed that preQ1 is absorbed into the bloodstream and tissues, where it significantly reduces cell proliferation in laboratory settings. Remarkably, this growth-inhibiting effect was reversed by the introduction of queuine, restoring normal growth rates.
Further investigation showed that injecting preQ1 into mice with tumors led to a reduction in tumor growth, suggesting its potential as a novel cancer treatment. The most pronounced effect of preQ1 was observed on dendritic cells, key immune cells responsible for initiating immune responses, with even small amounts completely halting their proliferation.
Timing and Molecular Mechanisms
The timing of exposure to these metabolites appears critical. PreQ1 is immediately available upon bacterial turnover, while queuine requires additional enzymatic reactions to be released. This means cells initially encounter the growth-slowing preQ1, followed by the growth-promoting queuine. This sequence may play a role in fine-tuning immune responses and maintaining tissue balance.
Researchers also identified the molecular mechanism behind preQ1’s effects. PreQ1 competes with queuine for the enzyme QTRT1/QTRT2, which modifies tRNAs. However, tRNAs modified by preQ1 are unstable and are subsequently destroyed by the cell’s quality control enzyme, IRE1. This degradation process can disrupt the translation of genes essential for cell growth and metabolism.
Implications for Host-Microbe Interactions
This study underscores the profound influence of bacterial metabolites on mammalian protein synthesis, demonstrating their ability to both slow and accelerate cell division. It suggests that bacterial chemistry extends beyond digestion and immunity, reaching into the core of cellular biology to regulate gene expression.
“These results show that the two microbial metabolites, born from the same pathway, can push our cells in opposite directions,” Pan stated. The opposing effects of preQ1 and queuine open up possibilities for manipulating the diet or microbiome composition to achieve a balance in cell growth, potentially offering new strategies for cancer treatment and autoimmune disease prevention.
The study, “Two microbiome metabolites compete for tRNA modification to impact mammalian cell proliferation and translation quality control,” was supported by grants from the National Institutes of Health, a pilot from the Univ. Chicago CIID Centre, the Chan-Zuckerberg Initiative, and the UCCCC Janet D. Rowley Discovery Fund. Additional authors include Wen Zhang, Sihao Huang, Olivia Zbihley, Dominika Rudzka, Luke Frietze, Mahdi Assari, Christopher Katanski, Marisha Singh, Christopher Watkins, Hankui Chen, Denis Cipurko, Amanda Sevilleja, Katherine Johnson, and Nicolas Chevrier from the University of Chicago; Kuldeep Lahry, Hélène Guillorit, Jennifer Falconi, Alexandre Djiane, Françoise Macari, Aurore Attina, Christophe Hirtz, and Alexandre David from the University of Montpellier, France; Delphine Gourlain and Didier Varlet from Hérouville Saint Clair, France.
