KAI-1 Protein Expression in Breast Cancer: Correlation with Axillary Lymph Node Metastasis and other Prognostic Factors

ABSTRACT

BACKGROUND: KAI-1 is a metastasis suppressor gene. We have evaluated the correlationbetween KAI-1 protein expression in ductal carcinomas of the breast and axillary lymph nodemetastasis. METHODS: The expression of KAI-1 protein was confirmed by immunohistochemistryto examine breast tissues of ductal carcinomas from 50 patients with nodal metastasisand from 53 patients without metastasis. Western blot analysis was performed on fresh frozenbreast tissues from 17 cases with nodal metastasis and from 19 cases without metastasis. RESULTS: Immunohistochemical KAI-1 protein expression was decreased or negative in 39out of 50 cases with metastasis (78%), compared with 8 out of 53 cases with no metastasis(15.1%). The difference was statistically significant (p<0.05). Immunohistochemical KAI-1protein expression was significantly decreased in cases with higher modified Black's nucleargrade (p=0.027) and larger tumor size (p=0.039). Western blot analysis showed positivebands at 29.5 kDa in 8 out of 19 cases without metastasis (42.1%), and none of the 17 caseswith metastasis showed positive bands (p=0.0024). CONCLUSION: These results suggest thepossibility that KAl-1 might play a major role of a metastasis suppressor gene in addition tothe part it plays in the growth and progression of human breast ductal carcinoma. In addition, the decreased expression of KAI-1 protein in breast ductal carcinomas could be used as afactor suggesting poor prognosis.