Elder J T, Kaplan A, Cromie M A, Kang S, Voorhees J J
Department of Dermatology, University of Michigan, Ann Arbor 48109-0672, U.S.A.
J Invest Dermatol. 1996 Mar;106(3):517-21. doi: 10.1111/1523-1747.ep12343887.
Cellular retinoic acid binding protein II (CRABP II) mRNA is selectively induced by all-trans retinoic acid in human skin and dermal fibroblasts. In order to determine whether this response can be used as a reliable measure of retinoid potency and activity, we treated human skin fibroblasts for 24 h with increasing concentrations of several natural and synthetic retinoids. CRABP II mRNA levels were measured by quantitative Northern blotting and compared, when possible, with those obtained after topical application of the same retinoids to human skin. All eight active retinoids tested induced a concentration-dependent CRABP II mRNA response in the fibroblast assay. In contrast, one known inactive retinoid (meta-carboxy TTNPB), differing from the active form only in the position of the carboxyl substituent, failed to evoke a response. The fibroblast and human skin bioassays agreed with respect to relative potency and response amplitude for three of the three retinoids tested. Retinoic acid was approximately 10-fold more potent than retinal in both assays, suggesting that oxidation to retinoic acid underlies the activity of retinol in fibroblasts as well as in intact skin. In support of this hypothesis, treatment with liarozole, an inhibitor of P450-mediated retinoic acid oxidative catabolism, significantly increased fibroblast CRABP II mRNA levels and potentiated the effects of retinol by 1.5-fold at concentrations at which it had no effect on its own. Taken together, these results identify the fibroblast CRABP II response as a reproducible measure of retinoid bioactivity with promise as a predictor of human skin responses and further suggest that metabolism is an important determinant of retinoid bioactivity in vivo.
细胞视黄酸结合蛋白II（CRABP II）mRNA在人皮肤和真皮成纤维细胞中由全反式视黄酸选择性诱导。为了确定这种反应是否可以用作类视黄醇效力和活性的可靠指标，我们用几种天然和合成类视黄醇的递增浓度处理人皮肤成纤维细胞24小时。通过定量Northern印迹法测量CRABP II mRNA水平，并在可能的情况下与将相同类视黄醇局部应用于人皮肤后获得的水平进行比较。在成纤维细胞试验中，所测试的所有八种活性类视黄醇均诱导了浓度依赖性的CRABP II mRNA反应。相比之下，一种已知的无活性类视黄醇（间羧基TTNPB），仅在羧基取代基的位置与活性形式不同，未能引发反应。对于所测试的三种类视黄醇中的三种，成纤维细胞和人皮肤生物测定在相对效力和反应幅度方面是一致的。在两种测定中，视黄酸的效力比视黄醛高约10倍，这表明氧化为视黄酸是视黄醇在成纤维细胞以及完整皮肤中发挥活性的基础。为支持这一假设，用P450介导的视黄酸氧化分解代谢抑制剂来罗唑治疗可显著提高成纤维细胞CRABP II mRNA水平，并在其自身无作用的浓度下将视黄醇的作用增强1.5倍。综上所述，这些结果确定成纤维细胞CRABP II反应是类视黄醇生物活性的可重复指标，有望作为人类皮肤反应的预测指标，并进一步表明代谢是体内类视黄醇生物活性的重要决定因素。
