Expression of cytokeratin 20 in urinary cytology of patients with bladder carcinoma.
BACKGROUND
Of the 20 known cytokeratins, CK-19 is expressed in normal urothelium, whereas the recently identified CK-20 is expressed in urothelial carcinoma cells but not in normal urothelial cells. The aim of this study was to examine whether CK-20 expression could serve as a noninvasive test in which malignant urothelial cells in urine are detected and monitored.


METHODS
In the current study, the authors used reverse transcriptase-polymerase chain reaction (RT-PCR) methods to determine the expression of CK-20 in cells separated from the urine of patients with bladder carcinoma. Cells were obtained from the urine of 87 patients divided into the following 2 groups: 1) 14 healthy volunteers without any known history of transitional cell carcinoma (TCC), and 2) 73 patients with hematuria suspected for TCC of the bladder. For control purposes, CK-20 expression was examined in cells of 1) bladder carcinoma tumors of 5 patients, 2) blood of either patients with bladder carcinoma (n = 5) or healthy controls (n = 5), and 3) three different cell lines. RNA of the various cell pellets was extracted and RT-PCR was performed with CK-20 and CK-19 primers (CK-19 was used as a marker for normal epithelial cells).


RESULTS
CK-20 amplification band (370 bp) was obtained with mRNA extracted from TCC cells of either bladder tumor or HT-29 line (a CK-20 colon carcinoma line). Sensitivity of the method was found to be 91%, whereas specificity was 67%. Among the 7 false-positive cases, 3 showed atypia, 3 hyperplasia, and 1 metaplasia, and 2 underwent previously successful TCC tumor removals, suggesting that the CK-20 test also responded to premalignant lesions. No false-positive cases were found in the healthy control group. No other preparation, including blood of the patients of with TCC, showed the CK-20 amplification band.


CONCLUSIONS
These results indicate that CK-20 is a potential biomarker for noninvasive detection of bladder carcinoma by assaying uroepithelial cells from the voided urine specimen with RT-PCR.
Klein
A
A
Laboratory of Molecular Biology, Sapir Medical Center, Sackler School of Medicine, Tel Aviv University, Kfar Saba, Israel.
Zemer
R
R
Buchumensky
V
V
Klaper
R
R
Nissenkorn
I
I
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis / Q000097:blood / Q000235:genetics* / Q000652:urine; D002295:Carcinoma, Transitional Cell / Q000097:blood / Q000473:pathology* / Q000652:urine; D005189:False Positive Reactions; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019073:HT29 Cells / Q000473:pathology; D006417:Hematuria / Q000473:pathology / Q000652:urine; D006801:Humans; D006965:Hyperplasia; D007633:Keratins / Q000032:analysis / Q000097:blood / Q000235:genetics* / Q000652:urine; D008297:Male; D008679:Metaplasia; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011230:Precancerous Conditions / Q000097:blood / Q000473:pathology / Q000652:urine; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D012680:Sensitivity and Specificity; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D001743:Urinary Bladder / Q000473:pathology*; D001749:Urinary Bladder Neoplasms / Q000097:blood / Q000473:pathology* / Q000652:urine; D019459:Urothelium / Q000473:pathology
D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D007633:Keratins