Phospatidylinositol 3-kinase expression in human breast cancer

Phospatidylinositol 3-kinase (PI 3-kinase) expression was analysed by Weste rn blotting with monoclonal antibodies to the p85 subunit in a series of tu mour and adjacent mammary gland samples collected at surgery from 33 breast cancer patients. Seventy-nine percent of the investigated pairs of the sam ples were characterised by an increased level of PI 3-kinase in the tumour in comparison with the adjacent mammary gland. PIS-kinase activation was no t associated with tumour steroid receptor status, histologic grade and othe r clinico-morphological characteristics. Furthermore, immunoblotting of epi dermal growth factor receptor (EGFR) in the tumours with increased PI S-kin ase and corresponding adjacent tissues revealed no association between EGFR and PI 3-kinase activation. Thus, increased PI 3-kinase expression appears to be a widespread feature of breast cancer not associated with the main b iological markers of its prognosis and hormone sensitivity. (C) 1999 Elsevi er Science BN. All rights reserved.