Sister chromatid exchange (SCE) rates in human melanoma cells as an index of mutagenesis

Miranda, Marta; Ligas, Claudio; Amicarelli, Fernanda; D'Alessandro, E.; Brisdelli, Fabrizia; Zarivi, Osvaldo; Poma, Anna

doi:10.1093/mutage/12.4.233

Cited by 17 publications

(8 citation statements)

References 22 publications

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“…Hill and Hill (1987) also reported that incubation with melanin caused DNA ssb and cell killing in mouse melanoma cells. Miranda et al (1997) described that an increase of melanin synthesis in human melanoma cells resulted in an increased rate of sister chromatid exchange as a result of DNA damage during replication. For the irradiated cells, however, further decrease of the cellular antioxidant levels is not very likely because the cells cultured in both the basic and the HT media exhibited similar sensitivity toward γ-rays, which is a well-known physical oxidative agent.…”

Section: Discussionmentioning

confidence: 99%

(Pheo)Melanin Photosensitizes UVA-Induced DNA Damage in Cultured Human Melanocytes

Wenczl

Schans

Roza

et al. 1998

Journal of Investigative Dermatology

166

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The question of whether melanins are photoprotecting and/or photosensitizing in human skin cells continues to be debated. To evaluate the role of melanin upon UVA irradiation, DNA single-strand breaks (ssb) were measured in human melanocytes differing only in the amount of pigment produced by culturing at two different concentrations, basic (0.01 mM) or high (0.2 mM), of L-tyrosine, the main precursor of melanin. In parallel, pheo- and total melanin contents of the cells were determined. Identical experiments were performed with two melanocyte cultures derived from a skin type I and a skin type VI individual. For the first time the correlation between UVA-induced genotoxicity and pheo-/total melanin content has been investigated. We observed that cultured in basic medium, the skin type VI melanocytes contained 10 times more total melanin and about seven times more pheomelanin than the skin type I melanocytes. Elevation of tyrosine level in the culture medium resulted in an increase of both pheo- and total melanin levels in both melanocyte cultures; however, the melanin composition of skin type I melanocytes became more pheomelanogenic, whereas that of skin type VI melanocytes remained the same. The skin type VI melanocytes cultured in basic medium demonstrated a very high sensitivity (1.18 ssb per 10(10) Da per kJ per m2) toward UVA that is probably related to their high pheo- and total melanin content. Their UVA sensitivity, however, did not change after increasing their melanin content by culturing at high tyrosine concentration. In contrast, the skin type I melanocytes demonstrated a low sensitivity (0.04 ssb per 10(10) Da per kJ per m2) toward UVA when cultured in basic medium, but increasing their melanin content resulted in a 3-fold increase in their UVA sensitivity (0.13 ssb per 10(10) Da per kJ per m2). These results demonstrate that UVA-irradiated cultured human melanocytes are photosensitized by their own synthesized chromophores, most likely pheomelanin and/or melanin intermediates.

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Section: Discussionmentioning

confidence: 99%

(Pheo)Melanin Photosensitizes UVA-Induced DNA Damage in Cultured Human Melanocytes

Wenczl

Schans

Roza

et al. 1998

Journal of Investigative Dermatology

166

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“…1, 2, 3 These spontaneous SCEs are considered a product of normal DNA replication or endogenous DNA damage. In addition, SCEs are induced by a variety of DNA-damaging agents such as mitomycin C (MMC) 4 or ionising radiation; 5 thus, alterations in DNA repair pathways have been associated with changes in SCE.…”

Section: Introductionmentioning

confidence: 99%

Reduced FANCD2 influences spontaneous SCE and RAD51 foci formation in uveal melanoma and Fanconi anaemia

et al. 2013

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Uveal melanoma (UM) is unique among cancers in displaying reduced endogenous levels of sister chromatid exchange (SCE). Here we demonstrate that FANCD2 expression is reduced in UM and that ectopic expression of FANCD2 increased SCE. Similarly, FANCD2-deficient fibroblasts (PD20) derived from Fanconi anaemia patients displayed reduced spontaneous SCE formation relative to their FANCD2-complemented counterparts, suggesting that this observation is not specific to UM. In addition, spontaneous RAD51 foci were reduced in UM and PD20 cells compared with FANCD2-proficient cells. This is consistent with a model where spontaneous SCEs are the end product of endogenous recombination events and implicates FANCD2 in the promotion of recombination-mediated repair of endogenous DNA damage and in SCE formation during normal DNA replication. In both UM and PD20 cells, low SCE was reversed by inhibiting DNA-PKcs (DNA-dependent protein kinase, catalytic subunit). Finally, we demonstrate that both PD20 and UM are sensitive to acetaldehyde, supporting a role for FANCD2 in repair of lesions induced by such endogenous metabolites. Together, these data suggest FANCD2 may promote spontaneous SCE by influencing which double-strand break repair pathway predominates during normal S-phase progression.

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“…However, melanin can also be photoreactive, especially pheomelanins containing photounstable benzothiazines, which can generate reactive oxygen species when irradiated by UV (10–12), and melanin precursors such as dihydroxy‐indole or related quinones may also behave as photooxidants (13). Stimulation of pigmentation in Caucasian‐cultured melanocytes was reported to increase sister chromatin exchange rate in melanoma cells (14) as well as DNA breakage in normal melanocytes after UV‐A exposure (15,16). Sun exposure is associated with an increased number of melanocytic nevi, which can be taken as an indicator of the risk for cutaneous melanoma (17).…”

Section: Introductionmentioning

confidence: 99%

Molecular Responses to Stress Induced in Normal Human Caucasian Melanocytes in Culture by Exposure to Simulated Solar UV^¶

Marrot

Belaïdi

Jones

et al. 2005

Photochem & Photobiology

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Melanocytes play a central role in the response of skin to sunlight exposure. They are directly involved in UV-induced pigmentation as a defense mechanism. However, their alteration can lead to melanoma, a process where the role of sun overexposure is highly probable. The transformation process whereby UV damage may result in melanoma initiation is poorly understood, especially in terms of UV-induced genotoxicity in pigmented cells, where melanin can act either as a sunscreen or as a photosensitizer. The aim of this study was to analyze the behavior of melanocytes from fair skin under irradiation mimicking environmental sunlight in terms of spectral power distribution. To do this, normal human Caucasian melanocytes in culture were exposed to simulated solar UV (SSUV, 300400 nm). Even at relatively high doses (until 20 min exposure, corresponding to 12 kJ/m2 UV-B and 110 kJ/m2 UV-A), cell death was limited, as shown by cell viability and low occurrence of apoptosis (caspase-3 activation). Moreover, p53 accumulation was three times lower in melanocytes than in unpigmented cells such as fibroblasts after SSUV exposure. However, an important fraction of melanocyte population was arrested in G2-M phase, and this correlated well with a high induction level of the gene GADD45, 4 h after exposure. Among the genes involved in DNA repair, gene XPC was the most inducible because its expression increased more than two-fold 15 h after a 20 min exposure, whereas expression of P48 was only slightly increased. In addition, an early induction of Heme Oxygenase 1 (HOZ) gene, a typical response to oxidative stress, was also observed for the first time in melanocytes. Interestingly, this induction remained significant when melanocytes were exposed to UV-A radiation only (320-400 nm), and stimulation of melanogenesis before irradiation further increased HOZ induction. These results were obtained with normal human cells after exposure to SSUV radiation, which mimicked natural sunlight. They provide new data TPosted on the website on

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Sister chromatid exchange (SCE) rates in human melanoma cells as an index of mutagenesis

Cited by 17 publications

References 22 publications

(Pheo)Melanin Photosensitizes UVA-Induced DNA Damage in Cultured Human Melanocytes

(Pheo)Melanin Photosensitizes UVA-Induced DNA Damage in Cultured Human Melanocytes

Reduced FANCD2 influences spontaneous SCE and RAD51 foci formation in uveal melanoma and Fanconi anaemia

Molecular Responses to Stress Induced in Normal Human Caucasian Melanocytes in Culture by Exposure to Simulated Solar UV^¶

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Sister chromatid exchange (SCE) rates in human melanoma cells as an index of mutagenesis

Cited by 17 publications

References 22 publications

(Pheo)Melanin Photosensitizes UVA-Induced DNA Damage in Cultured Human Melanocytes

(Pheo)Melanin Photosensitizes UVA-Induced DNA Damage in Cultured Human Melanocytes

Reduced FANCD2 influences spontaneous SCE and RAD51 foci formation in uveal melanoma and Fanconi anaemia

Molecular Responses to Stress Induced in Normal Human Caucasian Melanocytes in Culture by Exposure to Simulated Solar UV¶

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Molecular Responses to Stress Induced in Normal Human Caucasian Melanocytes in Culture by Exposure to Simulated Solar UV^¶