[Detection of urogenital malignant cells in the peripheral blood by nested RT-PCR using keratin 19 mRNA].

Introduction and Objectives: It is reported that cytokeratin 19 (CK-19) mRNA is not expressed in the peripheral blood cells of the healthy subjects (Am. J. Pathol. 142: 1111. 1993). Detection of DNA fragments of CK-19 in the peripheral blood suggests the existence of epithelial malignant tumor cells. In this study, we detected CK-19 genes in peripheral blood of patients with urogenital malignancy, and thus clarified the possibility of understanding tumor expansion.
Methods: Mononuclear cells were separated from the peripheral blood of 39 patients with urogenital tumor and 9 controls. Total cellular RNA was extracted according to the method described elsewhere. The CK-19 gene expression was investigated using nested reverse transcription polymerase chain reaction (nested RT-PCR) and confirmed by Southern Blotting. These results were compared to the clinical stages.
Results: CK-19 mRNA was not detected in any of 9 controls. CK-19 mRNA was detected in 3 out of the 10 bladder cancer cases. Two had metastases and 1 had muscle invasion without metastasis. One of 6 urothelial cancer case of the upper urinary tract showed positive amplification, and had liver, bone and lymphnode metastases. After one course of chemotherapy, mRNA became negative. In prostate cancer cases, three among 7 were positive and all 3 cases had distant metastases. In renal, testicular and penile cancer cases, the positive ratio were 3/6, 1/8 and 2/2, respectively. All positive cases of renal and testicular cancer had distant metastases, but one case of penile cancer had no metastasis.
Conclusion: The detection of CK-19 mRNA in the circulating blood by nested RT-PCR makes it possible to detect micrometastasis, to evaluate therapeutic effects and to predict the prognosis.