[The role of melatonin in growth of malignant choroid melanoma]

Increasing evidence of the immunomodulatory and tumor-depressing effects of melatonin prompted us to study altered concentrations of this multifunctional pineal hormone in the aqueous humor of eyes with melanoma. Eyes undergoing cataract surgery served as controls. First, RIA was used for the detection of melatonin (5 melanoma and 8 control eyes). In a second series we used ELISA with a newly developed antibody (6 melanoma and 11 control eyes). Moreover, the supernatant media of cultured melanomas were investigated for melatonin. We cautiously interpret the results as follows: (1) in the morning melatonin is detectable in the human aqueous humor at a concentration of ca. 35 pg/ml; (2) as blood serum and aqueous humor levels did not correlate, melatonin is probably actively secreted by the ciliary body rather than passively filtrated; (3) there are no significant changes in melatonin concentration in the aqueous humor of melanoma eyes; this, however, does not mean that melatonin does not play a role in uveal melanoma growth; (4) cultured uveal melanoma cells can probably synthesize melatonin.