The effect of ultraviolet radiation on choroidal melanocytes and melanoma cell lines: cell survival and matrix metalloproteinase production.
BACKGROUND
Ultraviolet radiation (UVR) can induce DNA damage and regulate the expression of factors important for tumour growth and metastasis, including matrix metalloproteinases (MMPs). Epidemiological studies suggest that chronic UVR exposure, especially during early adulthood, may be a risk factor in patients with choroidal melanoma. However, the effects of UV(R)-B on human choroidal melanocyte survival and growth are unknown. In this study, we investigated if UV(R)-B affected the in vitro survival, growth and MMP production of choroidal melanocytes and melanoma cells.


METHODS
Cultures of primary choroidal melanocytes and melanoma cell lines (OCM-1 and OCM-8) were exposed to UV(R)-B (0-30 mJ/cm(2)). The cell morphology and growth were examined, and cell viability was assessed using an MTT assay. Gelatin zymography was used to assess the enzymatic activity for MMP-2 and -9 in conditioned media following UV(R)-B treatment.


RESULTS
UV(R)-B > or =20 mJ/cm(2) was cytotoxic for choroidal melanocytes. Cytotoxic doses of 5 to 10 mJ/cm(2) were found for OCM-8 and OCM-1 melanoma cell lines. Low levels of UV(R)-B (2.5 and 3.5 mJ/cm(2)) significantly reduced melanoma cell viability after 48 h, although melanocyte viability was not affected by doses of UV(R)-B <10 mJ/cm(2). Conditioned media from melanoma cells and melanocytes displayed pro-MMP-2 activity independent of UV(R)-B. Control and UV(R)-B-treated OCM-1 cells secreted active MMP-2 up to 72 h. Pro-MMP-9 activity was seen from 36 h for control and UV(R)-B-treated OCM-1 and OCM-8 cells.


CONCLUSIONS
Melanocytes appeared more resistant to physiological doses of UV(R)-B than melanoma cells; the potential of melanocytes to initially survive DNA damage following UV(R)-B exposure may be relevant to the subsequent transformation of melanocytes to melanomas. Although UV(R)-B did not induce the production and/or activation of MMP-2 and -9 in melanocytes or melanoma cells, we are currently investigating whether DNA damage-response genes such as p53 and p21 can be regulated following UVR exposure, and whether they are important for choroidal melanoma development.
Lai
Kenneth
K
Save Sight Institute, Discipline of Clinical Ophthalmology, University of Sydney, Sydney, NSW, Australia. skl527@hotmail.com
Di Girolamo
Nick
N
Conway
Robert M
RM
Jager
Martine J
MJ
Madigan
Michele C
MC
D000328:Adult; D002453:Cell Cycle / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D002471:Cell Transformation, Neoplastic / Q000528:radiation effects; D002829:Choroid / Q000166:cytology*; D002830:Choroid Neoplasms / Q000201:enzymology / Q000473:pathology / Q000532:radiotherapy*; D004249:DNA Damage; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D020782:Matrix Metalloproteinases / Q000096:biosynthesis*; D008544:Melanocytes / Q000201:enzymology / Q000528:radiation effects*; D008545:Melanoma / Q000201:enzymology / Q000473:pathology / Q000532:radiotherapy*; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000209:etiology; D014407:Tumor Cells, Cultured / Q000528:radiation effects; D014466:Ultraviolet Rays
D020782:Matrix Metalloproteinases