title: The degree of pigmentation modulates the radiosensitivity of human melanoma cells.
abstract: The relationship between cell pigmentation and radiosensitivity was investigated in two selected human melanoma cell lines with different melanin content (mixed type: eumelanin and pheomelanin, and pheomelanotic phenotypes). The same study was also done after stimulation of melanogenesis (1) by addition of the melanin precursor l-tyrosine to each of the cell lines separately and (2) by irradiation alone with doses ranging from 0 to 10 Gy. We found that a decrease in cell radiosensitivity was correlated with the type of melanin, with a clear involvement of eumelanin rather than pheomelanin. Increasing the intracellular content of both melanins promoted the growth of irradiated cells. Moreover, at a dose of 10 Gy, both tyrosinase activity and melanin cell content were significantly increased in the absence of any other melanogenesis promoter. Our data suggest that the amount of intracellular melanin is inversely related to the radiosensitivity of melanoma cells and may explain at least in part the controversial responses to ionizing radiations reported for melanoma.
authors.affiliation: Laboratory of Oncology and Experimental Surgery, Institut J Bordet, Free University of Brussels, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Kinnaert
authors.forename: R
authors.initials: R
authors.lastname: Morandini
authors.forename: S
authors.initials: S
authors.lastname: Simon
authors.forename: H Z
authors.initials: HZ
authors.lastname: Hill
authors.forename: G
authors.initials: G
authors.lastname: Ghanem
authors.forename: P
authors.initials: P
authors.lastname: Van Houtte
mesh_terms: D002470:Cell Survival / Q000502:physiology / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008543:Melanins / Q000378:metabolism / Q000502:physiology*; D008545:Melanoma / Q000473:pathology / Q000532:radiotherapy*; D010858:Pigmentation; D011836:Radiation Tolerance / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D008543:Melanins