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Characterization of a dermal derived malignant mesenchymal tumor arising in ultraviolet irradiated mice
R G Phelps1, L E Bernstein, N Harpaz
1Department of Dermatology, Mount Sinai Medical Center, New York, NY 10029.
Abstract:
Skh/hr-1 hairless albino mice were irradiated with photocarcinogenic dosages of ultraviolet light for periods of 30 weeks or longer. A high proportion of mice developed pleomorphic spindle cell tumors and epidermal neoplasms of various types. These spindle cell tumors were studied by immunofluorescence and immunoperoxidase techniques and by electron microscopy. Freshly isolated tumor cells were grown in tissue culture. Immunocytochemical analysis showed varying expression of markers of mesenchymal differentiation: vimentin, procollagens I and III, type I collagen, and lysozyme. Electron microscopy showed spindled and cuboidal cells with abundant endoplasmic reticulum, filopodia, and lysosomes, but no intercellular connections. The cells grown in vitro were cuboidal and stellate and also showed mesenchymal differentiation by electron microscopy. These results are perhaps similar to those described for a human actinically produced fibrohistiocytic neoplasm, atypical fibroxanthoma, and this system may provide a useful model of ultraviolet-induced dermal neoplasia.
Insights
Ultraviolet (UV) light exposure in mice induced spindle cell tumors and epidermal neoplasms. These UV-induced skin tumors exhibit mesenchymal differentiation, offering a potential model for atypical fibroxanthoma.
Area of Science:
- Dermatology
- Oncology
- Cell Biology
Background:
- Ultraviolet (UV) radiation is a known carcinogen.
- UV exposure can lead to the development of skin neoplasms.
- Understanding the cellular mechanisms of UV-induced skin cancer is crucial.
Purpose of the Study:
- To investigate the characteristics of tumors induced by chronic UV irradiation in mice.
- To analyze the differentiation markers and ultrastructure of UV-induced spindle cell tumors.
- To evaluate the potential of this mouse model for studying actinic carcinogenesis.
Main Methods:
- Skh/hr-1 hairless mice were exposed to photocarcinogenic UV dosages.
- Tumor tissues were analyzed using immunofluorescence, immunoperoxidase techniques, and electron microscopy.
- Tumor cells were cultured in vitro for further characterization.
Main Results:
- A high incidence of pleomorphic spindle cell tumors and epidermal neoplasms was observed.
- Immunocytochemical analysis revealed varying expression of mesenchymal differentiation markers (vimentin, procollagens I and III, type I collagen, lysozyme).
- Electron microscopy showed cells with features of mesenchymal differentiation and no intercellular connections; in vitro cultured cells also exhibited mesenchymal traits.
Conclusions:
- UV-induced skin tumors in mice display mesenchymal differentiation.
- This experimental system may serve as a valuable model for studying ultraviolet-induced dermal neoplasia.
- The findings suggest similarities to human actinically produced fibrohistiocytic neoplasms like atypical fibroxanthoma.