Objective: To study the prostate specific antigen (PSA), prostate-specific membrane antigen (PSMA) and human glandular kallikrein (hK2) mRNA in peripheral blood samples of prostate cancer (PC) patients with bone metastasis by nested reverse transcriptase polymerase chain reaction (RT-PCR) based assay, and to discuss their clinical implications.
Methods: Samples of peripheral blood were analyzed by nested RT-PCR to identify PSA, PSMA and hK2 mRNA expression.
Results: RT-PCR assay was applied to identify the PSA, PSMA and hK2 mRNA expressing LNCaP cells, which were diluted by lymphocytes to 10(-6), 10(-6) and 10(-7) separately. Positive rates of the three markers in newly diagnosed PC patients with bone metastasis were 59.45%, 51.35% and 59.46% respectively, and 32.43% cases showed three positives. In PC patients who had developed bone metastasis after endocrine therapy, the positive rates were 57.14%, 85.71% and 83.33% respectively, and 52.48% cases showed three positives. All samples were negative in regional PC patients and healthy individuals, and all samples were positive for beta actin mRNA, the internal control.
Conclusion: Nested RT-PCR based assay for PSA, PSMA or hK2 mRNA helps to detect prostate cancer cells in the circulation system, thus providing evidence for occult metastasis. PSMA and hK2 were advisable markers to monitor disease progression after androgen blockage. Combined assays of PSMA and hK2 are suitable for patients who underwent endocrine therapy, and combined assays of the three markers have enhanced sensitivity.