ABSTRACT
PURPOSE: Breast cancer is one of the most frequent malignant tumors in Korea. The major tumor suppressor genes (TSGs) such as p16, Rb, E-cadherin and p53 may play important roles in cell cycle regulation, apoptosis and the regulation of the expression of other genes as well as tumor suppression. Microsatellite alteration such as loss of heterozygosity (LOH) have been reported to be a novel mechanism of carcinogenesis and a useful prognostic factor for many malignant tumors. Also, LOH is also known to be related with allelic loss of various TSGs. This study evaluated LOH of 4 TSGs in invasive ductal carcinomas (IDCs) and we correlated these results with the clinicopathological factors. METHODS: LOH analysis was carried out using a polymerase chain reaction with 12 polymorphic microsatellite markers of 4 TSGs in 50 surgically resected tumors and their non-tumorous counterparts. RESULTS: There was no detectable LOH in the normal tissue. LOH was detected in 86% of the 50 cases of IDCs. LOH was detected on all chromosomes and this showed a statistical difference between benign tumor and malignant tumor. LOH of p16, Rb, E-cadherin and p53 TSGs was detected in 36%, 26%, 54% and 60% of the tumors, respectively. LOH of the p16 and Rb genes was inversely correlated with tumor grade 1. The low rate of detecting LOH on the E-cadherin gene was noted in T1 tumor and stage I disease. LOH of the p53 gene correlated well with the tumor size and stage. The LOH-High results correlate well with the tumor size and stage and the LOH-High results are similar to those of the p53 gene LOH. CONCLUSION: These results suggest that LOH of the 4 major TSGs may contribute to the development and invasion of IDCs. Also, the combined use of various LOH markers may help in deciding the prognosis of IDCs.