The effects of UVA and UVB on proliferation and melanization in SK 23 melanoma cell lines

Lee, Mu Hyoung; Kim, Jin Hwan; Haw, Choong Rim

Abstract

BACKGROUND: The visible cutaneous pigmentary response to ultraviolet A(UVA) is immediate, whereas ultraviolet B(UVB)-induced pigmentation appears after a delay of several days. However, some investigators reported that UVA also can induce delayed taniing.
OBJECTIVE
In order to determine whether the pigmentation induceil by UVA irradiation is accompanied by melanocytes responses which are the same or different from those following a UVB-indueed tan, we irraiated malignant melanoma cells to UVA or UVB. METHOD: On the 7th day after irradiation of UVA or UVB, we exa nined the cell counts and the melanin content of control and experimental groups.
RESULTS
Although a dose of 10 J/cm decreased the number of manignant melanoma cells, there was no significant difference between the control and UVA-exposure griiups. But there was a significant decrease after UVB-exposun. UVB-exposure groups showed a significant increase of melanin cortent. A dose of 10 J/cm of UVA also induced a significant increase of melanin content.
CONCLUSIONS
The data suggest that UVA at a clinically relevant dose has a significant effect on human melanocytes. So, UVA very likely plays a role in the increased, melanization associated with delayed tanning.