Abstract

PURPOSE
Microsatellite instability in patients with defects in the mismatch repair system resulting in RER has a high risk of accumulating mutations in oncogene and tumor suppressor gene. In this study, we evaluated the incidence of microsatellite instability in breast cancer by comparing PCR-amplified sequences from frozen samples of normal and tumor tissue fram affected patients. We also investigated whether RER was associated with TGF-beta RII mutation.
MATERIALS AND METHODS
Fifty surgically resected breast cancer specimens from Jan. 1996 to June, 1997 were used for study. Microsatellite instability(referred to as replication error, RER) at three loci with BAT 26, BAT 40, TA10 was analyzed by polymerase chain reaction and the results were compared with clinicopathologic characteristics.
RESULTS
Of the 50 breast cancer patients, 14(28%) were RER(+) at one or more microsatellite loci, and 4(8%) showed TGF-beta RII mutation. Microsatellite instability was significantly correlated with lymph node involvement(especially in case of 4 or more lymph nodes involvement). But we could not find any correlation between RER and other prognostic factors including tumor size, tumor grade, hormone receptor status and pathology. One of fourteen tumors with RER(+) showed TGF-beta RII mutstion. There was no signiticant correlation between RER(+) and TGF-beta type II receptor gene mutation.
CONCLUSION
The findings suggest that microsatellite instability would be useful prognostic factor in unilateral breast cancer patients, and the role of targeting to gene mutation will be explored in future studies.

• Keywords: Breast cancer;Microsatellite instability;Replication error;TGF-beta;TGF-beta RII