Von Schroeder H P, Hashimoto Y, Heersche J N
MRC Group in Periodontal Physiology, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Teratology. 1994 Jul;50(1):54-62. doi: 10.1002/tera.1420500108.
RCJ C 5.18 (C 5.18) is a chondrogenic clonal cell line which, under standard culture conditions, develops chondroblastic features including the production of a cartilagenous matrix. Retinoic acid (RA) is known to inhibit the chondrogenic differentiation of C 5.18 cells and this may parallel the teratogenic effects of retinoids in vivo; however, the question as to which of the 3 retinoic acid receptors (RAR alpha, beta, gamma) or the 3 retinoid X receptors (RXR alpha, beta, gamma) mediate this RA-induced inhibition remains unanswered. We tested several retinoids with different receptor binding characteristics. Cartilage formation in C 5.18 cultures was evaluated by counting the number of cartilage nodules formed, and by quantitating the glycosaminoglycan content of the cultures using alcian blue staining. All of the retinoids prevented cartilage formation in a dose-dependent manner. Treatment with the retinoids did not affect cell number, thereby ruling out any toxic effects. RA, which binds to all 3 RARs with similar affinity, produced a 50% inhibition (IC50) of cartilage formation at 4 x 10(-10) M. We also tested Ch55, which also binds to all 3 RARs, but with higher affinity than RA. This compound was approximately 10 times more potent than RA (IC50 2 x 10(-11) M). 9-cis RA, which binds to the 3 RARs with affinities similar to RA and also binds to the 3 RXRs, was less active (IC50 8 x 10(-9) M), suggesting that RXR binding interferes with the inhibitory effect of ligand-activated RARs. 9-cis retinal, for which the binding characteristics are unknown, had the same effect as 9-cis RA.(ABSTRACT TRUNCATED AT 250 WORDS)
RCJ C 5.18（C 5.18）是一种软骨生成性克隆细胞系，在标准培养条件下，它会形成软骨母细胞特征，包括产生软骨基质。已知视黄酸（RA）会抑制C 5.18细胞的软骨生成分化，这可能与体内类视黄醇的致畸作用相似；然而，关于三种视黄酸受体（RARα、β、γ）或三种视黄醇X受体（RXRα、β、γ）中的哪一种介导这种RA诱导的抑制作用，这个问题仍未得到解答。我们测试了几种具有不同受体结合特性的类视黄醇。通过计数形成的软骨结节数量以及使用阿尔新蓝染色定量培养物中的糖胺聚糖含量，来评估C 5.18培养物中的软骨形成。所有类视黄醇均以剂量依赖性方式阻止软骨形成。用类视黄醇处理不影响细胞数量，从而排除了任何毒性作用。以相似亲和力与所有三种RAR结合的RA，在4×10⁻¹⁰ M时对软骨形成产生50%的抑制（IC50）。我们还测试了Ch55，它也与所有三种RAR结合，但亲和力高于RA。该化合物的效力比RA高约10倍（IC50 2×10⁻¹¹ M）。9-顺式视黄酸以与RA相似的亲和力与三种RAR结合，并且还与三种RXR结合，其活性较低（IC50 8×10⁻⁹ M），这表明RXR结合会干扰配体激活的RAR的抑制作用。结合特性未知的9-顺式视黄醛与9-顺式视黄酸具有相同的效果。（摘要截短于250字）
