Hungatella hathewayi: A Tumor-Derived Bacterium Enriched in Colorectal Cancer Tissues and a Potential Diagnostic Biomarker

Colorectal cancer (CRC) is the third most common cancer globally and the second leading cause of cancer-related deaths. While intestinal microbiota dysbiosis is linked to CRC, the direct role of intratumoral bacteria in metastasis remains poorly understood. In this study, we isolated pathogenic bacteria from CRC tumor tissues, identified as <i>Hungatella hathewayi</i> (<i>H. hathewayi</i>), through the 16S rRNA gene and whole-genome sequencing. We developed specific primers (P48/P52) and polyclonal antibodies for detecting <i>H. hathewayi</i> in samples. Using quantitative real-time PCR (qPCR), we found significant enrichment of <i>H. hathewayi</i> in fecal samples from CRC patients compared to healthy controls, with mean fold changes of 137-fold and 142-fold for primers P48 and P52, respectively. Analysis of tissue samples revealed that <i>H. hathewayi</i> abundance was higher in CRC tumor tissues compared to normal tissues, with mean fold changes of 2.90 for P48 and 3.97 for P52. Fluorescence in situ hybridization (FISH), immunofluorescence (IF), and immunohistochemistry (IHC) confirmed its spatial distribution within tumor tissues. In vitro assays using CRC cell lines demonstrated that <i>H. hathewayi</i>-derived succinate upregulates <i>HIF-1α</i> and <i>SUCNR1</i> expression and promotes cell metastasis by inducing epithelial-mesenchymal transition (EMT). Collectively, these findings identify <i>H. hathewayi</i> as a novel pro-metastatic bacterium and a potential non-invasive biomarker for CRC diagnosis, providing direct evidence for the role of intratumoral bacteria in CRC progression.