Microsatellite instability (MSI) and MLH1 and MSH2 protein expression analysis in postmenopausal women with sporadic endometrial cancer.

Microsatellite instability (MSI) seems to be important for the development of various human cancers including sporadic endometrial cancer. The aim of this study was evaluation of microsatellite instability in 60 postmenopausal women with endometrial cancer in DNA samples obtained from cancer tissue and blood of the same patients. Control DNA was obtained from normal endometrial tissue (n = 70). MSI was studied at five loci containing single- or dinucleotide repeat sequences and mapping to different chromosomal locations: BAT-25 (at locus 4q12), BAT-26 (2p16), D2S123 (2p16-p21), D5S346 (5q21-q22) and D17S250 (171q11.2-q12). No differences in the MSI frequencies between blood and cancer tissue obtained from patients were detected. The microsatellite instability status was significantly higher in endometrial cancer tissue [21/60 (35%)] compared to control [8/70 (11%)] (p < 0.05). There were significant differences between MSI presence in the subgroups assigned to the histological grades (p < 0.05). The lack of association between MLH1 and MSH2 protein expression and MSI in endometrial cancer samples was observed. The results suggest that the microsatellite instability seems to be important in the development of sporadic endometrial cancer.