Vimentin methylation as a potential screening biomarker for colorectal cancer in HIV-helminth co-infected individuals

Abstract

Colonoscopy remains the gold standard for colorectal cancer (CRC) screening, but its invasiveness, cost, and limited availability in resource-constrained settings pose major barriers. Stool-based methylated DNA biomarkers, such as vimentin, offer sensitive, non-invasive alternatives. Given the high burden of HIV and helminth co-infections in sub-Saharan Africa and their potential contribution to cancer susceptibility, this study investigated whether stool-derived vimentin methylation could detect early oncogenic changes in these high-risk groups. In this retrospective cross-sectional study, archived stool samples from 62 South African adults were stratified into five groups: uninfected controls, HIV-infected only, helminth-infected only, HIV-helminth co-infected, and CRC-confirmed patients. DNA was extracted, bisulfite-converted, and analyzed for vimentin methylation using a high-resolution melt assay. Fecal occult blood testing (FOBT) was also performed. Vimentin methylation differed significantly across groups (p < 0.0001). CRC cases showed 90% methylation, confirming its role as a CRC biomarker. Interestingly, vimentin methylation frequencies were also observed in HIV-only (92.9%, p < 0.0001 vs. controls), helminth-only (93.3%, p < 0.0001), and HIV-helminth co-infected (77.9%, p < 0.0001) individuals without diagnosed cancer, compared to 10% in controls. Methylation levels in infected groups were not significantly different from CRC patients (all p > 0.05), suggesting infection-induced epigenetic changes of comparable magnitude to malignancy. To support these results, DNMT1–RG108 molecular docking (PDB 4WXX, Maestro 2025-3) demonstrated stable binding (GlideScore −6.285 kcal/mol; ΔG_bind −49.61 kcal/mol) via hydrogen bonding with Glu1266 and Asn1578 and π–π stacking with Phe1145, providing a mechanistic explanation for infection-driven vimentin methylation. No significant differences were found between infected groups. FOBT was positive in 83.3% of CRC cases, with only sporadic positives in infected groups. These findings provide novel evidence that chronic HIV and helminth infections are associated with vimentin promoter methylation at levels indistinguishable from CRC. This supports the hypothesis that persistent infection-driven inflammation promotes early epigenetic reprogramming toward oncogenesis. In high-burden African settings, stool-based methylation assays could serve as early diagnostic tools to identify at-risk individuals long before clinical disease manifests, enabling targeted surveillance and prevention.