Detection of Tn-antigen in breast and prostate cancer models by VVL-labeled red dye-doped nanoparticles

<b>Aim:</b> Fluorescence detection of breast and prostate cancer cells expressing Tn-antigen, a tumor marker, with <i>Vicia villosa</i> lectin (VVL)-labeled nanoparticles. <b>Materials &amp; methods:</b> Breast and prostate cancer cells engineered to express high levels of Tn-antigen and non-engineered controls were incubated with VVL-labeled or unlabeled red dye-doped silica-coated polystyrene nanoparticles. The binding to cells was studied with flow cytometry, confocal microscopy, and electron microscopy. <b>Results:</b> Flow cytometry showed that the binding of VVL-labeled nanoparticles was significantly higher to Tn-antigen-expressing cancer cells than controls. Confocal microscopy demonstrated that particles bound to the cell surface. According to the correlative light and electron microscopy the particles bound mostly as aggregates. <b>Conclusion:</b> VVL-labeled nanoparticles could provide a new tool for the detection of Tn-antigen-expressing breast and prostate cancer cells. New VVL-labeled fluorescent red dye-doped silica-coated PS particles were developed and tested for detection of Tn-antigen, expressed only in malignant cells. Breast and prostate cancer cell lines gene-engineered to express Tn-antigen at a high level and non-engineered counterparts were used as models. The VVL-labeled particles bound specifically and effectively to Tn-antigen-expressing cells compared with their control cells as shown by flow cytometry. Confocal microscopy showed that the VVL-labeled particles were bound to the cell surface of target cells, mostly as aggregates. Further optimization to increase the intensity of the fluorescence and decrease the aggregation tendency of particles would help detect single particles. The VVL-labeled nanoparticles could be used for recognizing Tn-antigen-expressing cells (circulatory tumor cells) in blood samples of breast and prostate cancer patients, biopsies, or cryosections of tumor samples. In the future, they could also be developed to function <i>in vivo</i> as carriers for targeted therapy of Tn-antigen-expressing cancer.