β-Carotene Uptake and Bioconversion to Retinol Differ Between Human Melanocytes and Keratinocytes

Uppsala University, Uppsala, Uppsala, Sweden
Nutrition and Cancer (Impact Factor: 2.32). 02/2001; 39(2):300-6. DOI: 10.1207/S15327914nc392_21
Source: PubMed


beta-Carotene is one of the carotenoids that has been considered to play a role in the natural defense against ultraviolet-induced skin cancer. It is not known whether epidermal cells are able to accumulate beta-carotene and, subsequently, convert it to vitamin A. We used normal cultured human keratinocytes and melanocytes to study the uptake, and possible bioconversion to retinol, of authentic or [14C]beta-carotene. The uptake was much higher in melanocytes than in keratinocytes, corresponding to a fivefold difference in the intracellular fraction after two days of incubation. An increased level of cellular retinol was noted after one day of beta-carotene incubation. The conversion of [14C]beta-carotene to [14C]retinol peaked at 24 hours of incubation in keratinocytes and melanocytes. The results suggest that beta-carotene can function as a local supply of vitamin A in the skin and that melanocytes are especially likely to store beta-carotene.

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    • "( 94030304 ; Sigma - Aldrich , St . Louis , MO , USA ) were cultured in Eagle ' s minimum essential medium ( EMEM ) GlutaMAX , supplemented with 50 IU / ml penicillin - G , 50 µg / ml streptomycin , and 10% fetal bovine serum ( all from Gibco , Paisley , UK ) . Melanocytes were kindly provided by Petra Wäster and cultured as described previously ( Andersson et al . , 2001 ) . Human cervical cancer cells HeLa ( CCL - 2 ; ATCC ) , breast cancer cells MDA - MB - 231 ( HTB - 26 ; ATCC ) and human colon cancer HCT - 116 ( CCL - 247 ; ATCC ) were cultured in Dulbecco ' s modified eagle medium GlutaMAX supplemented with 50 IU / ml penicillin - G , 50 µg / ml streptomycin and 10% fetal bovine serum . Cells were "
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    • "All experiments were performed according to the ethical principles of the Helsinki declaration and approved by the Ethical Committee at Linkö ping University, Linkö ping, Sweden. Melanocytes were obtained from Caucasian donors (0–3 years of age) by means of foreskin circumcisions and pure cultures were established as described previously (Andersson et al., 2001). The melanocytes were cultured in Medium 199 with 2% fetal bovine serum and supplemented with 50 U/ml penicillin, 50 mg/ml streptomycin, 50 mg/ ml fungizone, 10 ng/ml basic fibroblast growth factor, 10 mg/ml inositol (all from Invitrogen, Paisley, Scotland, UK), 10 mg/ml insulin, 0.1 nM cholera toxin, 0.4 mg/ml hydrocortisone, 1 nM triiodothyronine , 10 mg/ml transferrin (all from Sigma Aldrich, St Louis, MO), and 10 ng/ml epidermal growth factor (Roche Diagnostics, Mannheim, Germany) (Gilchrest et al., 1984). "
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