Overexpression of p170 glycoprotein, the product of the multiple drug resistance(mdr) gene, has been associated with resistance to various cytotoxic drugs used in the treatment of human neoplasms. Benign breast(fibroadenoma) epithelial cells
express
very weakly p170 as a functon of their secretory capacity.
P170 glycoprotein expression was measured in 30 infiltrating ductal carcinomas and 5 fibroadenomas of breast using immunohistochemical staining with the monoclonal antibody C-219. Staining intensities of the whole tumor and of different area of
the
cryostat sections were transformed into digital numbers using an algolithm designed for this study.
The grade of histological differentiation of cancer cells was classified into well-, moderate-, and poorly- differentiated carcinoma according to Bloom and Richardson's classification. There were 6 cases in grade 1, 18 cases in grade Ⅱ, and 6
cases in
grade Ⅲ. Mean value of mdr gene expression as determined by staining with the C-219 monoclonal antibody was 2.17 in histologic grade 1, 1.94 in gradeⅡ, and 2.00 in gradeⅢ. There was no statistically significant correlation between histological
grade
and mdr gene expression.
It was concluded that the level of mdr gene expression as determined by C 219 monoclonal antibody does not correlate with the histological grades in locally advanced breast cancer.
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