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Updated: Aug 18, 2026
Spatial and Temporal Control of Murine Melanoma Initiation from Mutant Melanocyte Stem Cells
Published on: June 7, 2019
Metastasizing melanoma formation caused by expression of activated N-RasQ61K on an INK4a-deficient background
Julien Ackermann1, Manon Frutschi, Kostas Kaloulis
1ISREC, Swiss Institute for Experimental Cancer Research, National Center of Competence in Research Molecular Oncology, Epalinges, Switzerland.
Abstract:
In human cutaneous malignant melanoma, a predominance of activated mutations in the N-ras gene has been documented. To obtain a mouse model most closely mimicking the human disease, a transgenic mouse line was generated by targeting expression of dominant-active human N-ras (N-RasQ61K) to the melanocyte lineage by tyrosinase regulatory sequences (Tyr::N-RasQ61K). Transgenic mice show hyperpigmented skin and develop cutaneous metastasizing melanoma. Consistent with the tumor suppressor function of the INK4a locus that encodes p16INK4A and p19(ARF), >90% of Tyr::N-RasQ61K INK4a-/- transgenic mice develop melanoma at 6 months. Primary melanoma tumors are melanotic, multifocal, microinvade the epidermis or epithelium of hair follicles, and disseminate as metastases to lymph nodes, lung, and liver. Primary melanoma can be transplanted s.c. in nude mice, and if injected i.v. into NOD/SCID mice colonize the lung. In addition, primary melanomas and metastases contain cells expressing the stem cell marker nestin suggesting a hierarchical structure of the tumors comprised of primitive nestin-expressing precursors and differentiated cells. In conclusion, a novel mouse model with melanotic and metastasizing melanoma was obtained by recapitulating genetic lesions frequently found in human melanoma.
Insights
A novel mouse model for cutaneous malignant melanoma was created using a specific N-ras gene mutation. This model exhibits hyperpigmentation and develops metastatic melanoma, closely resembling human disease progression.
Area of Science:
- Oncology
- Genetics
- Dermatology
Background:
- Human cutaneous malignant melanoma frequently shows activated N-ras gene mutations.
- Developing accurate mouse models is crucial for understanding melanoma pathogenesis and testing therapies.
Purpose of the Study:
- To generate a transgenic mouse model that recapitulates key genetic alterations and clinical features of human cutaneous malignant melanoma.
- To investigate the role of N-ras activation and INK4a locus in melanoma development.
Main Methods:
- Generation of a transgenic mouse line (Tyr::N-RasQ61K) expressing dominant-active human N-ras in melanocytes.
- Analysis of melanoma development in INK4a-deficient (INK4a-/-) Tyr::N-RasQ61K mice.
- Characterization of primary tumors and metastases, including stem cell marker expression.
Main Results:
- >90% of Tyr::N-RasQ61K INK4a-/- mice developed melanoma by 6 months.
- The developed melanomas were melanotic, multifocal, invasive, and metastasized to lymph nodes, lung, and liver.
- Tumors exhibited a hierarchical structure with nestin-expressing stem cells.
Conclusions:
- A novel mouse model for melanotic and metastasizing melanoma has been successfully established.
- This model accurately reflects genetic lesions common in human melanoma, offering a valuable tool for research.
- The model demonstrates the utility of targeting N-ras and considering INK4a status for melanoma research.
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