Uveal melanoma is highly metastatic, prognosis is poor and there are no effective treatments to extend survival. Accumulating evidence suggests that thyroid hormones have a mitogenic effect via binding to αvβ3 integrin. We aimed to examine the impact of thyroid status on survival in a murine B16F10 model for ocular melanoma, highly expressing the integrin. In two independent experiments oral propylthiouracil (PTU) was used to induce hypothyroidism (n=9), thyroxine to induce hyperthyroidism (n=11) and mice given plain water served as control (n=8). At day 21, the subretinal space was inoculated with 10(2) B16F10 cells. In non-inoculated mice (n=6 of each group) serum free T4 (FT4) levels were measured and additional non-inoculated mice (3 given PTU and 4 given thyroxine or water) served as internal control to demonstrate the impact of the dissolved substance. The PTU-inoculated mice showed clinical evidence of intraocular tumor growth significantly later than the thyroxine mice (P=0.003) and survival time was significantly longer (P<0.001). FT4 levels differed significantly between groups (P<0.001) and with no signs of illness in the internal control group. Our findings suggest that hyperthyroidism shortens survival, whereas relative hypothyroidism may have a protective role in metastatic ocular melanoma.
Keywords: integrin; thyroid; uveal melanoma.