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PHOTOSENSITIZING EFFECTS OF 8‐METHOXYPSORALEN ON THE SKIN OF HAIRLESS MICE—11. TRAIN AND SPECTRAL DIFFERENCES FOR TUMORIGENESIS
Author(s) -
Grube D. D.,
Ley R. D.,
Fry R. J. M.
Publication year - 1977
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1977.tb06910.x
Subject(s) - hairless , psoralen , carcinogenesis , mouse strain , chemistry , fluorescence , strain (injury) , dna damage , carcinogen , dna , cancer research , microbiology and biotechnology , biophysics , biology , biochemistry , anatomy , optics , physics , gene
— The photosensitizing effects of 8‐methoxypsoralen on the skin of two strains of hairless mice were studied using fractionated exposure to UV Spectral dependent differences for tumorigenesis were studied by comparing the tumor responses to three different spectra; the exposure levels for each spectrum here adjusted in proportion to their relative efficiencies for tissue damage and cytokinetic responses. There were no strain differences in the spectral dependent induction of cutaneous damage or estimates of the photomediated interstrand cross‐linking of epidermal DNA by 8‐methoxypsoralen. Squamous cell carcinomas were induced in the photosensitized skin of both strains of mice after fractionated exposures to emissions at principally 365 nm. Exposures to a broader spectrum of light resulted in the earlier appearance of tumors in the photosensitized skin of the SKH: hairless‐1 mice, but produced few or no tumors in the HRS/J/Anl strain. In a second series of experiments ; mice were exposed to a fluorescent sun lamp prior to each combined treatment of psoralen and exposure at 365 nm to determine the influence of shorter wavelengths of UV on the tumor response. These treatments resulted in an enhanced expression of tumors in the SKH:hairless‐1 mice as compared to the HRS/J/Anl strain. Under the conditions of the experiments, the marked strain and spectral dependent differences for tumorigenesis demonstrated that although treatments that induce psoralen photoadducts also induce tumors. there was no apparent quantitative correlation between the occurrence of DNA cross‐links and the incidence of tumors. The results also suggested, first, an interaction between UV (280–400 nm) induced photoproducts and psoralen photoadducts and secondly, a strain difference in the oncogenic effects of this interaction.