Quercetin in bladder cancer: synergistic regulation of gut microbiota and L-serine metabolic pathway
In murine bladder cancer models, quercetin inhibited tumor progression by modulating gut microbiota and suppressing de novo L-serine synthesis via PSPH downregulation, with no clinical data in humans.
| Population | Murine bladder cancer models (MB49 and other cell lines) and human bladder cancer cell lines (T24, UMUC3) |
|---|---|
| Intervention | Oral quercetin (dose and duration not specified in available text); fecal microbiota transplantation (FMT) from treated animals |
| Comparator | Untreated control or vehicle |
| Outcome | Tumor progression (murine models); Gut microbiota composition; PSPH (phosphoserine phosphatase) expression; Intratumoral L-serine levels; In vitro cell viability (T24, UMUC3 cell lines) |
Summary of findings
| Outcome | Effect | 95% CI | Certainty | Clinical relevance | Notes |
|---|---|---|---|---|---|
| Tumor progression (murine models) | not reported with CI in available text | — | Very low | — | 1 studies |
| Gut microbiota composition | increased Bifidobacterium and Lactobacillus abundance; in the quantitative CI reported | — | Very low | — | 1 studies |
| PSPH (phosphoserine phosphatase) expression | downregulation reported; in the quantitative CI available in provided text | — | Very low | — | 1 studies |
| Intratumoral L-serine levels | reduction reported; in the quantitative CI available in provided text | — | Very low | — | 1 studies |
| In vitro cell viability (T24, UMUC3 cell lines) | reduced viable cell count at 40-60 micromol/L quercetin within 24h; in the CI reported | — | Very low | — | 1 studies |
Context
Bladder cancer has high recurrence rates after standard chemotherapy and immunotherapy. Quercetin has low oral bioavailability, and its in vivo antitumor mechanism remains inconclusive. This study tests the hypothesis that gut microbiota mediates part of quercetin's antitumor effect.
What the study showed
Quercetin reduced tumor progression in murine models, associated with shifts in gut microbiota composition (increased abundance of Bifidobacterium and Lactobacillus). The proposed mechanism involves PSPH downregulation, blocking de novo L-serine synthesis required for tumor growth. Absolute numbers, effect sizes with 95% CI, and p-values were not available in the provided text for extraction.
How it was done
Preclinical study combining in vivo murine tumor implantation models and in vitro cell line experiments. FMT was used to confirm microbiota involvement. Received October 2025, accepted November 2025; exact sample sizes and duration not reported in the available excerpt.
Effect magnitude
Numerical effect size (RR, OR, SMD, or MD with 95% CI) was not reported in the available text; the magnitude of the antitumor effect cannot be quantified from available data.
Risk of bias
Exclusively preclinical (in vivo murine and in vitro): no evidence in humans. No risk of bias tool applied (not a clinical trial). Microbiota–antitumor causality inferred via FMT but mechanistic link remains correlational. Quercetin dose, duration, and pharmacokinetics not detailed in the available excerpt.
What this study does NOT prove
This study does not prove quercetin antitumor efficacy in humans nor establishes causality between gut microbiota modulation and clinical tumor regression. Murine results are not directly extrapolatable to oncological practice.
In clinical practice
This study does not support any clinical recommendation for quercetin use in bladder cancer patients. Clinicians must not infer clinical efficacy from murine and cellular data. Phase I/II trials are required before any therapeutic consideration.
Limitations
Exclusively preclinical (in vivo murine and in vitro): no evidence in humans. No risk of bias tool applied (not a clinical trial). Microbiota–antitumor causality inferred via FMT but mechanistic link remains correlational. Quercetin dose, duration, and pharmacokinetics not detailed in the available excerpt.
What is still missing
Clinical trials in humans with bladder cancer to evaluate safety, pharmacokinetics, and efficacy of quercetin. Identification of the specific microbial component mediating the effect and reproducibility of PSPH modulation in human tissue are also needed.
Technical appendix
Version history
- 1.0 · 2026-10-29 — Auto-generated under Evidence Standard v1.0