Quantitative real-time RT-PCR assay for PCA3

Objectives: To develop a quantitative, internally standardized real-time RT-PCR assay for prostate cancer antigen 3 (PCA3), a non-translated gene found to be prostate-specific and highly overexpressed in cancer, and examine the role of PCA3 in peripheral blood with a small sample cohort. Design and methods: The RT-PCR assay for PCA3 is based on target-specific lanthanide probes. Peripheral blood from 91 prostatic cancer/disorder patients and healthy controls was assayed for PCA3 and prostate-specific antigen (PSA) expression. Results: The dynamic range of the assay reaches over eight orders of magnitude and the limit of quantification is 800 copies per milliliter blood. Peripheral blood from 2/9 patients with metastasized cancers were PCA3 positive, whereas all the other samples were negative. Eight samples were PSA positive. Conclusions: The degree of PCA3 positivity in circulating cells from prostate cancer patients is low compared to that of PSA. In contrast to some previous reports, we found no PCA3 expression in healthy individuals.