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Updated: Aug 10, 2026
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Focus Formation: A Cell-based Assay to Determine the Oncogenic Potential of a Gene
Published on: December 31, 2014
Cell context reveals a dual role for Maf in oncogenesis
C Pouponnot1, K Sii-Felice, I Hmitou
1Institut Curie, CNRS UMR 146, Centre Universitaire, Laboratoire 110, Orsay Cedex, France. Celio.Pouponnot@curie.u-psud.fr
Oncogene
|October 26, 2005
Summary
Maf b-Zip transcription factors act as oncogenes in some cells but not others. Their oncogenic activity depends on cell type and phosphorylation, revealing a dual role in cancer.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- Maf b-Zip transcription factors are implicated in cell differentiation and cancer.
- Their precise role in oncogenesis remains unclear due to seemingly contradictory functions.
Purpose of the Study:
- To investigate the oncogenic potential of Maf proteins in different cell types.
- To identify factors influencing Maf-mediated transformation.
Main Methods:
- Analysis of transformation parameters (e.g., anchorage-independent growth, growth factor independence) in chicken embryo fibroblasts and embryonic neuroretina cells.
- Site-directed mutagenesis to assess the role of MafA phosphorylation (Ser65).
- Examination of Maf protein interactions with the Ras/Raf/MEK pathway.
Main Results:
- MafA and c-Maf demonstrated potent oncogenic activity in chicken embryo fibroblasts, while MafB was weaker.
- MafA conferred growth factor independence and promoted low-density cell division.
- Phosphorylation at Ser65 in MafA was critical for its transforming activity.
- Maf proteins did not exhibit oncogenic activity in neuroretina cells and counteracted Ras/Raf/MEK-induced transformation.
Conclusions:
- Maf proteins exhibit context-dependent oncogenic functions, acting as oncogenes in some cells and tumor suppressor-like proteins in others.
- Maf's dual role in oncogenesis is influenced by cellular environment and post-translational modifications like phosphorylation.
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