Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.10.3.1 (tyrosinase)
 9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of four different retinoids [retinol, 13-cis-retinoic acid (Ro4-3780), beta-all-trans-retinoic acid, and aromatic retinoic acid ethyl ester (Ro10-9359)] on the cellular proliferation (cell number) and biochemical differentiation (tyrosinase activity) of a human melanoma cell line (MIRW) and three subclones was assessed. All four retinoids (10(-6) M) inhibited the cellular proliferation (36 to 42%) and stimulated tyrosinase activity (58 to 72%) in the parent cell line to a similar extent. In contrast, the effects of the different retinoids on three derived melanoma clones was dissimilar. For example, in clone A6, beta-all-transretinoic acid stimulated tyrosinase activity by 48% but caused only a 7% inhibition of cellular proliferation. This retinoid caused a more pronounced effect in the other two subclones, stimulating tyrosinase from 135 to 195% and inhibiting growth 19 to 33%. Al three melanoma clones demonstrated increased tyrosinase activity (110 to 225%) and reduced proliferation (37 to 52%) following exposure to 13-cis-retinoic acid. This retinoid was found overall to be the most effective stimulator of tyrosinase, while retinol was observed to be the least active, stimulating enzyme activity slightly (25%) in only one of three clones. Retinol inhibited proliferation 27 to 33% in two of three melanoma subclones. The aromatic retinoic acid ethyl ester elevated tyrosinase levels in two clones but inhibited the enzyme in one melanoma line. Cellular proliferation, however, was reduced in all three clones. These results suggest that retinoid-induced changes in human melanoma cell growth and differentiation reflect underlying cellular differences and diverse biochemical interactions.
 ...
PMID:Characterization of the effects of different retinoids on the growth and differentiation of a human melanoma cell line and selected subclones. 677 Sep 95

The effects of whey proteins from bovine milk on melanogenesis in cultured human melanocytes were examined. Among the major protein components of milk whey including beta-lactoglobulin (BLG), alpha-lactalbumin, serum albumin, and IgG, only BLG exhibited the depigmenting effect at a concentration of 1 mg/ml. Also, BLG suppressed the activity of tyrosinase in these cells. Retinol, to which BLG is known to bind, slightly increased the pigmentation of the cells at concentrations in the range of 1-100 nM, and retinoic acid, a metabolite of retinol, exhibited a strong pigmentation-promoting effect within the same concentration range. Treatment of the cells with 1 mg/ml BLG completely abrogated the pigmentation induced by these A vitamins. These results demonstrate a novel biological activity of BLG and suggest that this activity is dependent on its ability to bind retinol.
 ...
PMID:Beta-lactoglobulin suppresses melanogenesis in cultured human melanocytes. 942 9