Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Background:

It is accepted that X-ray irradiation influences growth, viability and metastatic potential of tumor cells. Furthermore, it is supposed that tumor cell invasion and metastasis is regulated by Eph receptors and their ephrin ligands. The aim of our study was to investigate the influence of irradiation on cell viability, growth, and metastasis in human melanoma cells and whether this is mediated by dysregulated Eph receptor or ephrin ligand expression.

Material and Methods:

Primary (Mel-Juso) and metastatic (A375, A2058) human melanoma cell lines were irradiated with 5 or 10 Gy. Up to 7 days after irradiation we examined cell viability (MTT test). At 1 day and 7 days post irradiation we further analyzed cellular growth, motility (scratch assay), adhesion to fibronectin, and migration through a porous membrane. Furthermore, the mRNA expression of 8 different Eph receptors and 6 ephrin ligands was analyzed using RT-PCR.

Results:

In all cell lines a dose dependent decrease in viability and cell growth for up to 1 week after irradiation was demonstrated. Analysis of metastatic properties 1 day after X-ray showed decelerated scratch closure, slight increase in migration, and increased adhesion to fibronectin in all investigated cell lines. In contrast, 1 week after irradiation we detected faster scratch closure in irradiated primary Mel-Juso cells but unaltered motility in metastatic cell lines and, moreover, decreased migration in primary Mel-Juso cells and, by trend also in metastatic A375 cells. In addition, in Mel-Juso and A375 cells capability to adhere to fibronectin remained elevated. RT-PCR analysis revealed that Eph receptors and ephrins investigated have similar mRNA expression levels in primary and metastatic cell lines, with exception of both EphA2 and ephrinA5 showing enhanced expression in metastatic A375 cells. After irradiation changes in mRNA expression were not
detected with exception of an increase in EphA2 and EphA3 in A375 cells and ephrins A1 and A5 in A375 and Mel-Juso cells 7 days after treatment.

Conclusion:

Irradiation considerably influences viability and metastatic properties of melanoma cells. The different effects depending on time after irradiation observed suggest an involvement of cell-cell interaction via A-type Eph receptors and ephrins in irradiation-induced metastatic potency of melanoma cells.