Several lines of evidence support the hypothesis that ultraviolet radiation (UVR) is involved in the etiology of cutaneous melanoma in humans. However, progress in understanding the mechanisms involved in induction of melanotic tumors by UVR has been hindered by lack of a suitable animal model. During the course of multiple exposures (3 times/wk for 70 wk) of the South American opossum, Monodelphis domestica, to UVR, we first observed the appearance of areas of dermal melanocytic hyperplasia (MH) on the exposed skin. Post-UVR exposure to photoreactivating light (320-500 nm) suppressed the occurrence of MH. We also observed at 100 weeks from first exposure that 10 of 46 surviving animals had developed melanotic tumors which arose, presumably, from areas of MH. Tumors on three of the 10 animals have been classified as malignant melanomas based on metastasis to lymph nodes. We conclude from these results that UVR can act as a complete carcinogen for melanoma induction and, based on the photoreactivation of MH induction, that DNA damage is involved in melanoma formation.
The interaction of actin with a synthetic peptide which corresponds to one of the repeated tubulin-binding sites present in tau and MAP-2 (microtubule-associated protein 2) proteins has been analysed. The analysis, which uses affinity chromatography of G-actin on a column containing the synthetic peptide, and the co-sedimentation and co-localization of F-actin and the peptide (as determined by immunoelectron microscopy), indicates that the part of the amino acid sequence of tau involved in the binding of tubulin is also involved in actin binding.
To identify and compare the gene expression profiles of actinic keratosis (AK) and squamous cell carcinoma (SCC) and to further clarify critical genetic alterations in the evolution of SCC from normal sundamaged human skin.
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