PM-TRPV4 positivity associated with invasive progression in patients with ductal carcinoma in situ

Purpose: Ductal carcinoma in situ (DCIS) is a non-invasive breast neoplasm frequently overtreated because biomarkers of invasive progression are lacking. We previously identified a pro-invasive mechanotransduction pathway in which ductal cell crowding inactivates plasma-membrane (PM) transient receptor potential vanilloid 4 (TRPV4), driving compensatory PM relocalization of intracellular inactive TRPV4 that marks pathway-engaged cells. Here, we evaluated whether PM-associated TRPV4 immunohistochemical staining on routine formalin-fixed paraffin-embedded DCIS sections is associated with subsequent invasive progression and assessed analytical validation of the antibody and scoring method. Methods: We performed a retrospective single-institution case-control study of 44 patients with pure DCIS: 24 who subsequently developed invasive ductal carcinoma and 20 who remained free of invasive progression for [≥]5 years. TRPV4 immunohistochemistry was scored for PM-TRPV4 on 225 pathology-annotated regions of interest (ROI) by three board-certified pathologists using a prespecified five-level rubric dichotomized for primary analyses as PM-positive or PM-negative. Orthogonal validation used a second human immunohistochemistry-validated TRPV4 antibody in representative ROI and cell-line models. Results: Orthogonal validation confirmed concordant compartmental TRPV4 distributions and mechanosensitive PM-TRPV4 relocalization in cell-line models. PM-TRPV4 scoring was highly reproducible (weighted Fleiss' {kappa}=0.823, 95% CI 0.777-0.863). PM-TRPV4 positivity was more frequent in progressors than non-progressors (22/24 vs 13/20), linked to shorter invasive progression-free survival (log-rank p=0.040), and was independently prognostic after adjustment for grade and estrogen receptor status (adjusted HR 3.77, 95% CI 1.01-14.12; p=0.049). Conclusions: These findings support PM-TRPV4 as a mechanism-informed, pathology-interpretable biomarker for DCIS risk stratification, with reproducible scoring and a preliminary prognostic signal warranting multi-institutional validation.