PROTEIN-TYROSINE KINASE-ACTIVITY IN BREAST-CANCER AND ITS RELATION TOPROGNOSTIC INDICATORS

Tyrosine kinase dependent oncogenes and growth factor receptors are of prognostic importance in breast cancel, but the relation of cytosolic protein tyrosine kinase (PTK) activity to traditional prognostic indi cators is poorly defined. We determined cytosolic PTK activity in tumo r extracts of 61 women with invasive beast cancel; including 51 primar y specimens and 12 nodal oi metastatic specimens, 7 women with in situ breast cancel; and 8 control breast specimens. PTK activity (pmol/min /mg) was measured in a dot blot assay using phosphotyrosine antibodies to detect phosphorylated tyrosyl residues in the tissue extracts. Com pared with control specimens (mean PTK=20.5), tyrosine kinase activity was significantly greater in invasive primary cancels (mean PTK=298.1 ; p=0.0008), and nodal/metastatic specimens (mean PTK=491.5; p=0.0009) . PTK levels of invasive cancels did not correlate with age (p=0.36), tumor size (p=0.83), nodal status (p=0.37), estrogen receptor status ( p=0.66), or progesterone receptor status (p=0.09). Thus, while tyrosin e kinase activity is increased in breast cancer; correlations with tra ditional prognostic indicators were not found.