Oral communication, CS4 / C16

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

Ultraviolet B, but not ultraviolet A initiates and promotes melanoma formation in metabotropic glutamate receptor 1 transgenic mouse

Metabotropic glutamate receptor subtype 1 (mGluR1) is a G protein coupled receptor activated by glutamate, and is functionally expressed in the central nervous system. We have previously shown that ectopic expression of mGluR1 in melanocytes is essential for both development and in vivo growth of melanoma in double transgenic mice, NSE-tTA /TRE-mGluR1. Using these transgenic mice, we irradiated once at day 3 and three times a week for 2 months from day 30 by ultraviolet B (UVB) at 1.5 J/cm2 or UVA at 14 J/cm2. Single irradiation by UVB at day 3 induced melanoma formation earlier than non-irradiated group, and repetitive irradiation for 2 months promoted melanoma growth. In case of UVA irradiation, this induction or promotion of melanoma formation was not observed. To see whether melanin species and contents affect UV-induced melanoma formation, we created yellow mice which dominantly contain pheomelanin by crossing transgenic mice with recessive yellow mice. In yellow mice, UVB but not UVA induced and promoted melanoma formation. Initiation of melanoma occurrence was earlier in yellow mice compared with that in black mice, however melanoma promotion rate was not significantly changed between yellow and black mice. These results indicate that initiation and promotion of melanoma can be induced by UVB, but not UVA irradiation and pheomelanin might be involved in initiation of melanoma formation.

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