Microsatellite status and immunohistochemical features of ovarian clear-cell carcinoma.

BACKGROUND Ovarian clear-cell carcinoma (OCC) is known to have a poor prognosis and selected genetic features of OCC remain unknown. We investigated microsatellite instability (MSI) and the expression of the DNA mismatch repair-related protein, p53. MATERIALS AND METHODS MSI was examined by polymerase chain reaction using mono-, di-, tri- and tetranucleotide repeat markers, and hMSH2, hMLH1, hMSH6, MSH3 and p53 were determined immunohistochemically in 24 cases of OCC. RESULTS A total of 9 (37.5%) cases exhibited MSI. Two cases (8.3%) exhibited MSI-H in mononucleotide repeat loci with the negative expression of hMLH1, while another 7 cases (29.2%) exhibited selected trinucloetide repeat MSI (MSI-TR). Of these MSI-TR cases, 4 cases (57.1%) were determined to be negative for MSH3, while hMSH2, hMSH6, MSH3 and p53 expressions were normal. CONCLUSION Our findings suggest that MSI-TR would be a feature indicating the microsatellite status in OCC, and that the loss of MSH3 expression may promote MSI-TR.