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Invasive melanoma in Cdk4-targeted mice
R Sotillo1, J F García, S Ortega
1Molecular Oncology, Centro Nacional de Investigaciones Oncológicas and Centro Nacional de Biotecnologia, Consejo Superior de Investigaciones Cientificas, 28029 Madrid, Spain.
Abstract:
Many human tumors harbor mutations that result in deregulation of Cdk4 activity. Most of these mutations involve overexpression of D-type cyclins and inactivation of INK4 inhibitors. In addition, a mutation in the Cdk4 protein has been described in patients with familial melanoma (Wolfel, T., Hauer, M., Schneider, J., Serrano, M., Wolfel, C., et al. (1995) Science 269, 1281-1284; Zuo, L., Weger, J., Yang, Q., Goldstein, A. M., Tucker, M. A., et al. (1996) Nat. Genet. 12, 97-99). This mutation, R24C, renders the Cdk4 protein insensitive to inhibition by INK4 proteins including p16(INK4a), a major candidate for the melanoma susceptibility locus. Here we show that knock-in mice expressing a Cdk4 R24C allele are highly susceptible to melanoma development after specific carcinogenic treatments. These tumors do not have mutations in the p19(ARF)/p53 pathway, suggesting a specific involvement of the p16(INK4a)/Cdk4/Rb pathway in melanoma development. Moreover, by using targeted mice deficient for other INK4 inhibitors, we show that deletion of p18(INK4c) but not of p15(INK4b) confers proliferative advantage to melanocytic tumor growth. These results provide an experimental scenario to study the role of Cdk4 regulation in melanoma and to develop novel therapeutic approaches to control melanoma progression.
Insights
Mice with a specific Cdk4 mutation (R24C) developed melanoma, indicating the p16INK4a/Cdk4/Rb pathway
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Deregulation of Cyclin-dependent kinase 4 (Cdk4) activity is common in human tumors.
- Mutations often involve D-type cyclins overexpression and INK4 inhibitor inactivation.
- A specific Cdk4 R24C mutation confers resistance to INK4 inhibition, implicated in familial melanoma.
Purpose of the Study:
- To investigate the role of the Cdk4 R24C mutation in melanoma development.
- To explore the involvement of the p16INK4a/Cdk4/Rb pathway in melanoma pathogenesis.
- To assess the contribution of other INK4 inhibitors in melanocytic tumor growth.
Main Methods:
- Generation of knock-in mice expressing the Cdk4 R24C allele.
- Carcinogenic treatments to induce melanoma.
- Analysis of tumor mutations, including the p19ARF/p53 pathway.
- Utilizing targeted mice deficient for p18INK4c and p15INK4b.
Main Results:
- Cdk4 R24C knock-in mice showed high susceptibility to melanoma after carcinogenic treatment.
- Developed melanomas lacked mutations in the p19ARF/p53 pathway.
- Deletion of p18INK4c, but not p15INK4b, promoted melanocytic tumor growth.
Conclusions:
- The p16INK4a/Cdk4/Rb pathway plays a specific role in melanoma development.
- Cdk4 regulation is crucial in melanoma progression.
- This model provides a platform for studying melanoma and developing new therapies.