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Expression of Ly-6.2 and Thy-1 antigens on NIH 3T3 cells suppressed after transformation with activated human
Abstract:
We have studied the expression of several cell surface antigens in NIH 3T3 cells after neoplastic transformation with activated human ras and myc oncogenes. The binding of monoclonal antibodies (MAbs), specific for mouse differentiation antigens Ly-6.2, Thy-1 and 9F3, to normal and transformed cells was assessed using a fluorescence-activated cell sorter (FACS IV). Significant reduction of Ly-6.2 and Thy-1 antigen expression was detected in cells transformed with either the N-ras, Ki-ras or H-ras oncogenes but not in c-myc transfected cells. 9F3 antigen expression remained at the original high level in all transfectants studied. Normal levels of Ly-6.2 and Thy-1 expression reappeared in revertants derived from unstable ras-transfectants. These data indicate that ras sequences did not preferentially transform cells that were deficient in Ly-6.2 and Thy-1 antigens. It was also shown that the reduced binding of anti-Ly-6.2 antibodies to ras-transfectants was not due to a masking effect of increased cell-surface sialylation occurring in ras-transfected cell lines. Other possible explanations of the detected phenotypic changes are discussed. The results extend the range of tumor-associated membrane alterations in NIH 3T3 cells following transfection with human tumor DNA containing activated ras oncogenes by a hitherto unreported alteration in the expression of Ly-6 and Thy-1 antigens.
Insights
Ras oncogenes significantly reduce Ly-6.2 and Thy-1 cell surface antigen expression in NIH 3T3 cells, unlike myc oncogenes. This finding reveals novel tumor-associated membrane alterations in ras-transformed cells.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Neoplastic transformation involves changes in cell surface antigens.
- Ras and myc oncogenes are implicated in cellular transformation and cancer development.
Purpose of the Study:
- To investigate the impact of activated human ras and myc oncogenes on cell surface antigen expression in NIH 3T3 cells.
- To identify novel tumor-associated membrane alterations in ras-transformed cells.
Main Methods:
- NIH 3T3 cells were transfected with activated human ras or myc oncogenes.
- Expression of Ly-6.2, Thy-1, and 9F3 antigens was assessed using monoclonal antibodies and fluorescence-activated cell sorting (FACS IV).
Main Results:
- Ras oncogene transfection (N-ras, Ki-ras, H-ras) led to a significant reduction in Ly-6.2 and Thy-1 antigen expression.
- c-myc transfection did not alter Ly-6.2 and Thy-1 expression.
- 9F3 antigen expression remained unchanged in all transfectants.
- Reduced antigen expression was restored in revertant cell lines derived from ras-transfectants.
- Increased cell-surface sialylation did not account for the reduced antibody binding to ras-transfectants.
Conclusions:
- Ras oncogenes induce specific alterations in cell surface antigen expression (Ly-6.2 and Thy-1) during NIH 3T3 cell transformation.
- These findings expand the known repertoire of membrane changes associated with ras-mediated transformation.
- The study suggests that ras oncogenes, but not myc, are responsible for the observed downregulation of Ly-6.2 and Thy-1 antigens.