Induction and transplantation of murine skin cancers induced by methoxsalen plus ultraviolet (320-400 nm) radiation

Properties of skin tumors resulting from treatment of mice with ip methoxsalen plus UVA (320-400 nm) radiation (PUVA) were compared to those of skin tumors induced by UVB (280-320 nm) radiation. Repeated treatment of C3H/HeN murine mammary tumor virus-negative (C3H-) mice with PUVA produced both fibrosarcomas and squamous carcinomas that were indistinguishable morphologically from UVB-induced tumors. Fragments of 12 primary PUVA-induced tumors were transplanted into normal and immunosuppressed syngeneic recipients, and all grew progressively. In contrast, 19 primary tumors induced by repeated exposure of C3H- mice to UVB grew only in the immunosuppressed mice and not in the normal recipients. The growth of graded doses of cells from 5 PUVA-induced tumors was compared in normal and UVB-irradiated recipients. No preferential growth in UVB-irradiated mice was observed, even though this is characteristic of UVB-induced tumors. Thus PUVA-induced tumors do not appear to have the same antigenic properties as UVB-induced tumors