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Inhibition of transforming activity of tyrosine kinase oncogenes by herbimycin A
Y Uehara1, Y Murakami, S Mizuno
1Department of Antibiotics, National Institute of Health, Tokyo, Japan.
Abstract:
We studied the effectiveness of herbimycin A, an inhibitor of the function of the temperature-sensitive src oncogene, to reverse the morphologies of chicken and mammalian cells transformed by various oncogenes. It was found that the antibiotic was effective against the cells transformed by tyrosine kinase oncogenes src, yes, fps, ros, abl, erbB, but did not reverse the transformed morphologies induced by oncogenes raf, ras, and myc. Moreover, decreases in phosphotyrosine content of the total cellular proteins and in 36K protein phosphorylation by herbimycin treatment supported the selective inhibition of the antibiotic on the transforming activity of tyrosine kinase oncogenes.
Insights
Herbimycin A effectively reversed cell transformations caused by tyrosine kinase oncogenes but not others like raf or ras. This selective inhibition targets specific oncogenic pathways.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Cellular transformation by oncogenes leads to abnormal cell morphology and uncontrolled growth.
- Tyrosine kinase oncogenes play a critical role in cell signaling pathways that regulate cell growth and differentiation.
- Understanding the specific mechanisms of oncogene-induced transformation is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the effectiveness of herbimycin A, an inhibitor of the temperature-sensitive src oncogene, in reversing oncogene-induced cell morphologies.
- To determine the selectivity of herbimycin A against various oncogenes, particularly tyrosine kinase oncogenes.
- To elucidate the molecular mechanisms underlying herbimycin A's action on cellular transformation.
Main Methods:
- Treatment of chicken and mammalian cells transformed by various oncogenes with herbimycin A.
- Morphological assessment of cells following herbimycin A treatment.
- Analysis of cellular phosphotyrosine content and specific protein phosphorylation levels (e.g., 36K protein) after herbimycin A exposure.
Main Results:
- Herbimycin A successfully reversed the transformed morphologies of cells induced by tyrosine kinase oncogenes, including src, yes, fps, ros, abl, and erbB.
- The antibiotic did not reverse the transformed morphologies caused by non-tyrosine kinase oncogenes such as raf, ras, and myc.
- Herbimycin A treatment led to decreased phosphotyrosine content in total cellular proteins and reduced phosphorylation of a 36K protein, supporting its selective action.
Conclusions:
- Herbimycin A exhibits selective efficacy against oncogene-induced cellular transformation mediated by tyrosine kinases.
- The findings suggest that herbimycin A can be a valuable tool for studying the specific roles of tyrosine kinase oncogenes in cancer.
- Herbimycin A's mechanism involves the inhibition of phosphotyrosine signaling pathways critical for oncogenic transformation.