ABSTRACT
Tyrosine protein kinase (TPK) activity is associated to malignant cellular transformation. This work compares TPK activity in 27 surgical biopsy samples of mammary carcinoma, 10 samples of normal mammary tissue. TPK activity was determined in tissue homogenates using (Val5) angiotensin II as exogenous substrate. In samples of mammary carcinoma, TPK activity was 33.86 ñ 31.98 pmol P32/mg protein/30 min. This value was significantly higher that those observed in fibrocystic disease (3.92 ñ 2.35), fibroadenomas (13.86 ñ 10.9) and normal tissue (3.56 ñ 3.02)
Subject(s)
Humans , Female , Adult , Middle Aged , Protein-Tyrosine Kinases/biosynthesis , Breast Neoplasms/enzymology , Breast/enzymology , Breast Diseases/enzymology , Carcinoma/enzymology , Case-Control Studies , Fibroadenoma/enzymologyABSTRACT
c-erbB-2 oncogene encodes a growth factor receptor whose amino acid sequence has extensive homology with human epidermal growth factor receptor. It is frequently overexpressed in human breast, ovary, lung, and stomach cancers, where its overexpression is related significantly to the prognosis. Tl investigate the possible role of c-erbB-2 oncogene in the oncogenesis of stomach cancer, we examined the genetic alterations of c-erbB-2 oncogene in 4 stomach cancer cell lines, SNU-1, SNU-5, SNU-16 and KATO III. There were no differences in c-erbB-2 mRNA level as well as c-erbB-2 gene copy number among them. But gp185-erbB-2, c-erbB-2 gene product, was increased from 2- to 4-fold in SNU-1 and SNU-5 cells, compared with that in SNU-16 or KATO III cells. Our results suggest that post-transcriptional regulation of gp185erbB-2 expression may underlie gp185erbB-2 overexpression in cancer cells.