In a groundbreaking study poised to reshape therapeutic approaches to gastric cancer, researchers have unveiled the potent anti-cancer effects of quercetin, a naturally occurring flavonoid, through its modulation of a critical metabolic axis. The investigation, published in BMC Cancer in 2025, meticulously explored the molecular mechanisms underpinning the suppression of gastric cancer cell proliferation and migration, illuminating the role of the IDO1-Kynurenine-AhR pathway in disease progression.
Gastric cancer remains a formidable clinical challenge worldwide, attributed largely to its aggressive nature and resistance to conventional therapies. Scientists have long sought to identify molecules capable of curbing tumor growth and metastasis without incurring debilitating side effects. This study centers on quercetin, a compound richly found in fruits and vegetables, that has demonstrated promising anti-cancer properties in various malignancies but whose exact mechanisms in gastric cancer were previously unclear.
The investigative team employed two human gastric cancer cell lines—AGS and MKN-45—to model the disease environment in vitro. These cells were treated with quercetin alongside well-established chemotherapeutic agents paclitaxel and cisplatin to provide a comparative framework for efficacy. The post-treatment analyses were comprehensive, assessing cellular viability, apoptosis, cell cycle disruption, migration, and invasive potential.
Quantitative techniques revealed that quercetin significantly diminished cell viability across both GC cell lines, paralleling the effects observed with paclitaxel and cisplatin. Flow cytometric assays substantiated these findings by demonstrating an increase in programmed cell death and notable cell cycle arrest. Additionally, the flavonoid impaired the cells’ intrinsic capabilities to invade and migrate, two hallmarks of metastatic potential. These functional bioassays provided compelling evidence of quercetin’s multi-modal anti-tumor activity.
At the molecular level, the researchers zoomed in on a metabolic cascade associated with immune evasion and tumor progression—tryptophan catabolism via the indoleamine 2,3-dioxygenase 1 enzyme (IDO1). Dysregulation of this enzymatic pathway leads to the accumulation of kynurenine, a metabolite known to activate the aryl hydrocarbon receptor (AhR), fostering an immunosuppressive microenvironment conducive to cancer growth.
Advanced gene and protein expression analyses demonstrated a coordinated downregulation of IDO1, its paralog IDO2, tryptophan 2,3-dioxygenase (TDO), kynurenine 3-monooxygenase (KMO), and AhR following treatment with quercetin. This concerted suppression disrupted the metabolic axis, potentially reinstating immune surveillance mechanisms and inhibiting oncogenic signaling pathways modulated by AhR activation.
The study’s findings hold significant translational implications. By attenuating the IDO1-Kynurenine-AhR axis, quercetin not only hampers the intrinsic proliferative and migratory capacities of gastric cancer cells but may also reprogram the tumor microenvironment towards a less permissive state. This dual action underscores the flavonoid’s potential as a complementary or alternative therapeutic agent, especially for patients who experience adverse effects from standard chemotherapy.
Comparative analysis showed that quercetin’s efficacy paralleled traditional chemotherapeutic drugs in several key aspects, yet it is presumed to carry a more favorable toxicity profile, given its dietary origin and established safety in humans. The study advocates further preclinical and clinical assessments to verify dosing regimens, bioavailability, and combinational strategies that include quercetin for optimal patient outcomes.
Moreover, the research invites a broader reconsideration of targeted metabolic pathways in oncology. Tryptophan metabolism and AhR signaling have emerged as critical nodes in cancer biology, interfacing metabolism, immunity, and cell behavior. Interventions like quercetin that can modulate these axes hold promise for undermining tumor resilience and enhancing immune-mediated clearance.
The methodology employed in this research exemplifies rigorous cellular and molecular interrogation. CCK-8 assays quantified cell viability changes, while flow cytometry enabled precise measurement of apoptosis rates and cell cycle alterations, providing mechanistic insights at the cellular level. The wound healing and Transwell assays served to quantify migration and invasion respectively, critical functional parameters linked to metastatic competence.
Molecular interrogation was conducted using quantitative PCR and Western blotting, tools that quantified gene transcription and protein translation of targeted enzymes and receptors within the tryptophan metabolism pathway. This multi-layered approach ensured robustness of conclusions, revealing quercetin’s capacity to suppress mRNA and protein levels synchronously.
The novelty of this study lies in identifying quercetin as a modulator of the IDO1-Kynurenine-AhR axis specifically in gastric cancer—a pathway previously implicated predominantly in immune regulation but now underscored as a direct influencer of aggressive tumor phenotypes. By delineating this link, the authors pave the way for a novel class of therapeutics aimed at metabolic reprogramming.
Further exploration into the pharmacodynamics and pharmacokinetics of quercetin will be vital to translate these promising in vitro findings into clinically effective interventions. The modulation of the tryptophan metabolism axis by flavonoids may extend beyond gastric cancer, opening vistas for cross-cancer therapeutic strategies exploiting metabolic vulnerabilities.
The potential integration of quercetin into combinatorial treatment regimens, possibly enhancing the efficacy of existing chemotherapeutic agents while mitigating their side effects, could revolutionize the management pipeline. Precision targeting of metabolic enzymes may overcome treatment resistance, a frequent barrier to successful cancer control.
In summation, this research heralds a promising horizon in oncological therapeutics where naturally derived compounds like quercetin can exert profound anti-cancer effects by targeting intricate metabolic and signaling networks. The suppression of the IDO1-Kynurenine-AhR axis emerges as a pivotal mechanism through which gastric cancer proliferation and migration can be restrained, offering hope for improved prognoses.
The implications extend beyond biological curiosity, touching on the clinical promise of integrating dietary phytochemicals into the armamentarium against one of the deadliest cancers globally. As the scientific community intensifies its focus on tumor metabolism, studies such as this underscore the necessity of holistic approaches marrying natural compounds with precision oncology.
Subject of Research: Gastric cancer cell proliferation and migration inhibition via modulation of IDO1-mediated tryptophan metabolism.
Article Title: Quercetin inhibits gastric cancer cell proliferation and migration and is associated with the suppression of the IDO1-Kynurenine-AhR axis.
Article References: Zhu, M., Hu, Q., Lu, Y. et al. Quercetin inhibits gastric cancer cell proliferation and migration and is associated with the suppression of the IDO1-Kynurenine-AhR axis. BMC Cancer (2025). https://doi.org/10.1186/s12885-025-15308-0
Image Credits: Scienmag.com
