Breast cancer: oncogenes and suppressor genes

Molecular aetiology and pathogenesis of basal cell carcinoma

Recent insights into the cell biology of the epidermis and its appendages are transforming our understanding of the pathogenesis of basal cell carcinoma (BCC). The significant progress that has been made warrants a comprehensive review of the molecular and cellular pathology of BCC. The items addressed include environmental and genetic risk factors, the biology of the putative precursor cell(s), and the contribution of aberrations in processes such as apoptosis, cell proliferation, differentiation and signalling to carcinogenesis. Furthermore, established and novel treatment modalities are discussed with particular attention to future biological approaches.

Prognostic factors in human primary breast cancer: comparison of c-myc and HER2/neu amplification

Amplification of oncogenes in primary tumours may have prognostic and/or therapeutic significance for patients with breast cancer. We have studied HER2/neu and c-myc amplification together with steroid receptors in human primary breast tumours and related the outcome with (relapse-free) survival. A strong inverse correlation was found between HER2/neu amplification and the presence of oestrogen and progesterone receptors. Actuarial 5-years survival showed that breast cancer patients with c-myc amplification in their primary tumours experience a shorter relapse-free survival, especially in node-negative and in receptor-positive tumours, whereas HER2/neu amplification may be of prognostic value for overall survival in receptor-negative tumours. Overall, in our hands, c-myc amplification appeared to be a more potent prognosticator than HER2/neu amplification in human primary breast cancer.

Regulation of surface-differentiation molecules by epidermal growth factor, transforming growth factor alpha, and hydrocortisone in human mammary epithelial cells transformed by an activated c-Ha-ras proto-oncogene

Spontaneously immortalized human mammary epithelial cells MCF-10A were transfected with an activated c-Ha-ras oncogene. Transfected cells (MCF-10T) acquire a malignant phenotype, as already reported. Studies of 125I-2'-deoxyuridine incorporation in cultures given graded doses of hydrocortisone (HC), cholera toxin (CT), epidermal growth factor (EGF), and transforming growth factor alpha (TGF-alpha) showed that though MCF-10T had become almost independent on exogenous EGF and TGF-alpha, they continued to respond to the synergistic effect of HC and CT plus EGF. Both lines were phenotypically characterized with an immunoradiometric assay in live cells. Expression of MHC class-I molecules, human milk-fat-globule-I antigen, and EGF receptor was reduced in ras-transfected cells, although other differentiation markers were unchanged. Exogenous EGF down-regulated the expression of functional EGF-R, selectively in transformed cells. TGF-alpha failed to modulate EGF-R. In contrast, HC strongly stimulated the expression of EGF-R while depressing MHC class-I molecules. Thus, it appears that in vivo HC may co-operate with TGF-alpha and EGF in promoting the growth of transformed mammary cells. This hormone might also favor the escape from immune surveillance by reducing the expression of surface differentiation markers.