Carlie G, Ntusi N B A, Hulley P A, Kidson S H
Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, 7925, Cape Town, South Africa.
Br J Dermatol. 2003 Oct;149(4):707-17. doi: 10.1046/j.1365-2133.2003.05577.x.
Khellin is a naturally occurring furochromone which, when combined with artificial ultraviolet (UV) A or solar irradiation (KUVA), is reported to repigment vitiligo skin as effectively as PUVA photochemotherapy. The exact mechanism of KUVA-induced repigmentation is unknown.
The aim of this study was to test the effect of khellin and KUVA on proliferation and melanogenesis of normal human melanocytes and Mel-1 melanoma cells in vitro.
Cultured normal human melanocytes, Mel-1 melanoma cells and fibroblasts were treated with khellin, UVA and KUVA and the effect on proliferation determined by cell counting. The effect on melanogenesis was determined by a radiometric melanin formation assay. Changes in gene expression and protein synthesis were determined by Northern blot, reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analyses.
Khellin stimulated proliferation of Mel-1 melanoma cells and melanocytes at concentrations between 1 nmol L-1 and 0.5 mmol L-1 with a peak effect at 0.01 mmol L-1 khellin. In contrast, khellin inhibited proliferation of fibroblasts over the entire concentration range tested. At concentrations above 0.5 mmol L-1, khellin was cytotoxic to both melanocytic cells and fibroblasts. Exposure of khellin-treated cells to single doses of UVA between 150 and 280 mJ cm-2 resulted in an enhanced proliferative effect. Khellin and KUVA also stimulated the melanogenic enzyme activity of pigmented cells, with the most effective treatment being 0.01 mmol L-1 khellin with 250 mJ cm-2 UVA. Western blot, Northern blot and RT-PCR analysis revealed that these increases in melanogenic enzyme activity were not due to increases in gene expression or protein synthesis. UVA treatment resulted in an increase in enzyme glycosylation and this correlated with the increase in melanogenesis.
We conclude that khellin activated by UVA stimulates melanocyte proliferation and melanogenesis. Our results point to the possibility that current treatment regimens might be improved if reduced khellin doses are applied and suggest that improved delivery vehicles be tested.
凯林是一种天然存在的呋色酮，据报道，当与人工紫外线A（UV）A或日光照射（KUVA）联合使用时，其使白癜风皮肤复色的效果与补骨脂素光化学疗法（PUVA）一样有效。KUVA诱导复色的确切机制尚不清楚。
本研究旨在体外测试凯林和KUVA对正常人黑素细胞及Mel - 1黑色素瘤细胞增殖和黑素生成的影响。
用凯林、UVA和KUVA处理培养的正常人黑素细胞、Mel - 1黑色素瘤细胞和成纤维细胞，通过细胞计数确定对增殖的影响。通过放射性黑色素形成试验确定对黑素生成的影响。通过Northern印迹法、逆转录聚合酶链反应（RT - PCR）和蛋白质印迹分析确定基因表达和蛋白质合成的变化。
凯林在1 nmol/L至0.5 mmol/L的浓度范围内刺激Mel - 1黑色素瘤细胞和黑素细胞的增殖，在0.01 mmol/L凯林时达到峰值效应。相比之下，在测试的整个浓度范围内，凯林抑制成纤维细胞的增殖。在浓度高于0.5 mmol/L时，凯林对黑素细胞和成纤维细胞均具有细胞毒性。将经凯林处理的细胞暴露于150至280 mJ/cm²的单剂量UVA会导致增殖效应增强。凯林和KUVA还刺激色素细胞的黑素生成酶活性，最有效的处理是0.01 mmol/L凯林与250 mJ/cm² UVA。蛋白质印迹、Northern印迹和RT - PCR分析表明，这些黑素生成酶活性的增加并非由于基因表达或蛋白质合成的增加。UVA处理导致酶糖基化增加，这与黑素生成的增加相关。
我们得出结论，UVA激活的凯林刺激黑素细胞增殖和黑素生成。我们的结果表明，如果应用降低剂量的凯林，当前的治疗方案可能会得到改善，并建议测试改进的给药载体。
