Detection of micrometastasis by cytokeratin-20 (reverse transcription polymerase chain reaction) in lymph nodes of patients with endometrial cancer.
BACKGROUND
Cytokeratins are constituents of the intermediate filaments (IFs) of epithelial cells which are expressed in various combinations, depending on the type of epithelium and degree of differentiation. We have reported (R. Zemer, A. Fishman, J. Bernheim, S. Zimlichman, O. Markowitz, M. Altaras, and A. Klein, Gynecol Oncol 70:410-413, 1998) on the determination of cytokeratin-20 (CK-20) by reverse transcription polymerase chain reaction (RT-PCR) in the detection of endometrial cancer cells as a potential biomarker. In that study, we also found that by using immunocytochemistry, most carcinomas were found to be negative for CK-20. The sensitivity and specificity rates obtained by using the RT-PCR method were 94.4 and 91%, respectively.


OBJECTIVE
The aim of this study is to investigate the feasibility and potential of the specific mRNA marker, CK-20, to detect endometrial cancer cells-micrometastases (MMs)-by RT-PCR in lymph node (LN) samplings of patients undergoing hysterectomy for endometrial carcinoma.


METHODS
We used the RT-PCR method to determine the expression of CK-20 in the LNs of 20 patients [study group (SG)] who were being surgically staged and treated for endometrial carcinoma. The specificity of the mRNA CK-20 marker was examined in LNs obtained from five healthy patients [control group (CG)] who underwent abdominal hysterectomy and bilateral salpingo-oopherectomy for benign gynecologic conditions. The LNs obtained from the SG and CG patients were prepared together before mRNA extraction. RNA of the various cell pellets was extracted and RT-PCR was performed with CK-20 primers. RT-PCR products were analyzed by agarose gel electrophoresis and ethidium bromide staining against PCR size markers. Specificity of the RT-PCR products was examined by Southern blotting.


RESULTS
Histopathologic examinations demonstrated the presence of metastases in two (10%) SG patients. These patients were also CK-20 positive. Of the remaining 18 patients with negative histopathologic results, 6 (33%) were CK-20 positive and 12 (67%) were negative. All the CG patients were CK-20 negative (specificity, 100%).


CONCLUSIONS
The results obtained in this study suggest that RT-PCR of CK-20 is more sensitive than traditional histopathologic methods in the diagnosis of MMs in LNs of patients with endometrial cancer. Thus, due to the aforementioned characteristics of CK-20, it may be considered a powerful biomarker in the detection of MMs in LNs of patients with endometrial cancer.
Fishman
A
A
Gynecologic Oncology Unit, Sapir Medical Center, Kfar Saba, 44281, Israel.
Klein
A
A
Zemer
R
R
Zimlichman
S
S
Bernheim
J
J
Cohen
I
I
Altaras
M M
MM
D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology / Q000556:secondary*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D017931:DNA Primers; D016889:Endometrial Neoplasms / Q000235:genetics / Q000473:pathology*; D005260:Female; D006801:Humans; D007381:Intermediate Filament Proteins / Q000032:analysis* / Q000096:biosynthesis; D053554:Keratin-20; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009367:Neoplasm Staging; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction
D014408:Biomarkers, Tumor; D017931:DNA Primers; D007381:Intermediate Filament Proteins; C507499:KRT20 protein, human; D053554:Keratin-20; D012333:RNA, Messenger