Integration of gut microbiome and lipid metabolism reveals the anti-cancer effects of pentadecanoic acid on bladder cancer

Pentadecanoic acid (PEA), an odd-chain fatty acid derived from diet by the gut microbiome, has garnered increasing attention for its systemic health-promoting properties. Its potential role in bladder cancer (BC) occurrence and invasion, however, remains unclear. Large-scale cohorts’ analyses were performed to assess the association between dietary PEA and BC occurrence and invasion. In vitro and in vivo experiments, including EJ and T24 BC cell assays and a BBN-induced mouse model, were conducted to experimentally assess the impact of PEA on BC. Serum proteomics, gut microbiome, and targeted fecal lipidomics analyses were employed to explore the underlying mechanisms. Dietary PEA was negatively associated with BC occurrence and invasion in cohort analyses. PEA suppressed EJ and T24 BC cell migration, invasion, and proliferation, while inhibiting BC development in a BBN-induced mouse model. In vivo serum proteomics identified differentially expressed lipid-related proteins (e.g., Apoe and Apob) following PEA treatment, implicating its modulation of lipid metabolism pathways. Considering the essential role of the gut-bladder axis, the gut microbiome analysis exhibited that PEA markedly altered bacteria (e.g., g_ Alistipes ) and fungi (e.g., o_ Erysiphales , g_ Teberdinia , and g_ Gibberella ), with concomitant lipid metabolism changes. Furthermore, targeted fecal lipidomics demonstrated the shifts in key lipids, such as phosphatidylethanolamines (PE) involved in essential lipid clusters, suggesting regulation by gut microbiome linked to BC development. Collectively, our findings demonstrate that PEA mitigates BC by reshaping the gut microbiome and modulating lipid metabolism, providing new insights into its molecular and therapeutic potential. This study aims to investigate the effects of PEA on BC occurrence and invasion using multi-dimensional approaches. We found PEA showing the protective effect on BC based on large-scale cohorts, in vitro and in vivo experiments. This observation may be mediated by the gut microbiome’s involvement in the lipid-metabolism pathway, potentially highlighting a gut-bladder axis in BC. Abbreviations: PEA, pentadecanoic acid; BC, bladder cancer; BCPP, Bladder Cancer Prognosis Programme; CCK-8, Cell Counting Kit-8; DIA MS, Data-Independent Acquisition Mass Spectrometry; 16S rRNA, 16S ribosomal RNA; ITS, Internal Transcribed Spacer; LC-MS/MS, Liquid Chromatography-Tandem Mass Spectrometry; PE, phosphatidylethanolamine.