PCA3 Responsive Molecular Imaging Enables Spatial Visualization of Prostate Cancer

PCA3 is an established prostate cancer biomarker. Here, we investigated its use as a molecular trigger for fluorescence activation and spatial visualization of prostate cancer. We developed CaS-DNA, an RNA-responsive molecular beacon that activates the near-infrared fluorophore indocyanine green upon PCA3 recognition. CaS-DNA showed sequence-specific hybridization and target-dependent fluorescence activation, with signal intensity strongly correlating with PCA3 expression across prostate cancer cell models (R = 0.96) and minimal activation in non-malignant controls. Selective labeling was maintained in spatially defined co-cultures and prostate cancer xenografts. In freshly resected human prostate tissue, CaS-DNA fluorescence corresponded with histopathologically defined tumor regions and showed tumor-coverage comparable to PSMA-targeted molecular imaging. Spatial transcriptomic analysis demonstrated concordance between CaS-DNA fluorescence and tumor-associated transcriptional profiles, while heterogeneous fluorescence was associated with local differences in transcript abundance. CaS-DNA converts endogenous PCA3 expression into spatially resolved near-infrared fluorescence, providing a molecularly guided approach for prostate cancer visualization and assessment.