Oncoprotein expression in human breast epithelial cells transformed by high-LET radiation.
OBJECTIVE
The aim of the present work was to analyze the expression of oncoproteins that are frequently altered in breast cancer with specific phenotypic stages in the neoplastic process.


METHODS
Expression of c-myc, c-jun, c-Ha-ras and the tumor suppressor gene p53 oncoproteins were examined by immunohistochemical staining coupled with confocal microscopy in transformed and tumorigenic human breast epithelial cells induced by high-LET alpha-particles (150 kcV/microm).


RESULTS
MCF-10F cells, irradiated with single and double doses of 60 cGy alpha-particles and subsequently treated with cstrogen, showed gradual phenotypic changes including altered morphology, increased cell proliferation relative to control, anchorage-independent growth, invasive capabilities and tumorigenicity in nude mice. MCF-10F cells irradiated with a second dose of 60 cGy alpha-particles after estrogen treatment (60 cGy+ E/60 cGy+E) showed tumorigenicity both in SCII) and nude mice. Alterations in the protein expression of several oncogenes including c-myc, c-jun, c-Ha-ras and the tumor suppressor gene p53 were detected in alpha-particle-irradiated cells and in those cells subsequently cultured in the presence of estrogen. The expression level of these oncoproteins correlated with the progressive nature of the neoplastic process.


CONCLUSIONS
These studies suggest that overexpression of several oncoproteins is important in the neoplastic transformation of human breast epithelial cells induced by high-LET radiation. In addition, use of endocrine factors such as estrogen allows the examination of various aspects of protein expression providing the basis for understanding the complex interactions of hormones and genes.
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Center for Radiological Research, College of Physicians and Surgeons of Columbia Unviersity, New York, NY 10032, USA. gmc24@columbia.edu
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D000818:Animals; D001940:Breast / Q000378:metabolism* / Q000528:radiation effects*; D001943:Breast Neoplasms / Q000209:etiology* / Q000378:metabolism*; D002448:Cell Adhesion; D002455:Cell Division / Q000528:radiation effects; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism* / Q000528:radiation effects*; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008819:Mice, Nude; D016513:Mice, SCID; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009368:Neoplasm Transplantation; D010641:Phenotype; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis
D004967:Estrogens; D016755:Proto-Oncogene Proteins c-jun; D016271:Proto-Oncogene Proteins c-myc; D016159:Tumor Suppressor Protein p53; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)