Ultraviolet B radiation differentially modifies catechol-O-methyltransferase activity in keratinocytes and melanoma cells

Authors

  • Sofia Magina,

    1. Institute of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal
    2. Institute for Molecular and Cell Biology,, University of Porto, Porto, Portugal
    3. Dermatology and Venereology Department, H. S. João, Porto, Portugal
    Search for more papers by this author
  • Maria Augusta Vieira-Coelho,

    1. Institute of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal
    2. Institute for Molecular and Cell Biology,, University of Porto, Porto, Portugal
    Search for more papers by this author
  • Maria Paula Serrão,

    1. Institute of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal
    Search for more papers by this author
  • Carina Kosmus,

    1. Institute of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal
    Search for more papers by this author
  • Eduardo Moura,

    1. Institute of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal
    2. Institute for Molecular and Cell Biology,, University of Porto, Porto, Portugal
    Search for more papers by this author
  • Daniel Moura

    1. Institute of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal
    Search for more papers by this author

  • Conflicts of interest:

    None declared.

Correspondence:

Sofia Magina, Instituto de Farmacologia e Terapêutica, Faculdade de Medicina, Universidade do Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal.

Tel: +351 225513642

Fax: +351 225513643

e-mail: smagina@med.up.pt

Summary

Background

Catechol-O-methyltransferase (COMT) is a ubiquitous enzyme inactivating catecholic compounds. COMT is expressed also in human skin samples, and in melanoma cells it may be cytoprotective. A role of COMT in keratinocytes (HaCat) is unknown.

Objective: The objective of this study is

to investigate whether ultraviolet-B (UVB) radiation modifies COMT activity in melanocytes and HaCat and whether COMT inhibition plays a role in UVB-induced cell death.

Methods

Human cell lines of melanotic melanoma (SK-mel-1) and HaCat were used. COMT activity was evaluated under basal conditions and after UVB irradiation (311 nm) at a low (8 mJ/cm2) and a high dose (60 mJ/cm2). Tolcapone 1 μM was used to inhibit COMT.

Results

Both SK-mel-1 and Ha-Cat cells express COMT activity. In SK-mel-1, COMT activity is reduced nearly 50% both 24 h and 48 h after a high dose UVB. In Ha-Cat cells, COMT activity increased 24 h after a high dose UVB but decreased at 48 h. Tolcapone increases significantly the cytotoxic effect of high dose UVB irradiation only in HaCat. High concentrations of tolcapone reduced melanin levels in melanoma cells parallel to reduced cell numbers.

Conclusions

Ultraviolet radiation differentially modifies COMT activity in melanoma cells and HaCat. Furthermore, tolcapone increased death of HaCat after irradiation but did not affect melanoma cells.

Ancillary