Berkers J A, Hassing I, Spenkelink B, Brouwer A, Blaauboer B J
Research Institute of Toxicology, Utrecht University, The Netherlands.
Arch Toxicol. 1995;69(6):368-78. doi: 10.1007/s002040050186.
Dioxins are potent inducers of chloracne in humans. This skin aberration can be interpreted as an altered differentiation pattern of acinar sebaceous base cells and a change in the rate of terminal differentiation of the keratinocytes. We measured this rate induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in primary cultures of human keratinocytes. As parameters for differentiation, we quantified the 35S-methionine incorporation into cross-linked envelopes (revealing the total CLE biomass), as well as the number of microscopically visible CLEs. It was shown that TCDD is a very potent inducer of both CLE biomass and number with a half-maximal effect concentration (EC50) of 1.4 nM. CLE biomass was maximally increased 10-fold and the number of cells in culture producing a CLE was increased from 15% in control cultures to maximally 75% of the cells in TCDD-treated cultures. Both effects were Ca(2+)-dependent and increased with elevated cell density, being optimal in post-confluent cultures. Retinoic acid dose-dependently decreased the effect of 10(-8) M TCDD, 10(-6) M having a nearly complete antagonistic action. This interaction of retinoic acid with TCDD-induced differentiation was non-competitive. Retinol was equally potent as an antagonist of the TCDD-induced elevation of CLE formation as compared with retinoic acid. Retinyl palmitate and etretinate were not very effective as TCDD antagonists. Supplementation of hydrocortisone suppressed the TCDD-induced keratinocyte differentiation. It was concluded that CLE biomass quantification provides a reliable and sensitive parameter for keratinocyte differentiation. In this in vitro system it is shown that TCDD strongly induces a switch from proliferation to terminal differentiation and that this effect can be antagonized effectively by retinoic acid and retinol.
二噁英是人类氯痤疮的强效诱导剂。这种皮肤病变可被解释为腺泡皮脂腺基底细胞分化模式的改变以及角质形成细胞终末分化速率的变化。我们在人角质形成细胞原代培养物中测量了2,3,7,8-四氯二苯并对二噁英（TCDD）诱导的这种速率。作为分化参数，我们量化了35S-甲硫氨酸掺入交联包膜中的量（揭示交联包膜的总生物量）以及显微镜下可见的交联包膜的数量。结果表明，TCDD是交联包膜生物量和数量的非常强效的诱导剂，半数最大效应浓度（EC50）为1.4 nM。交联包膜生物量最大增加了10倍，培养物中产生交联包膜的细胞数量从对照培养物中的15%增加到TCDD处理培养物中细胞的最大75%。这两种效应均依赖于Ca(2+)，并随着细胞密度的升高而增加，在汇合后培养物中最为明显。视黄酸剂量依赖性地降低了10(-8) M TCDD的作用，10(-6) M具有几乎完全的拮抗作用。视黄酸与TCDD诱导的分化之间的这种相互作用是非竞争性的。与视黄酸相比，视黄醇作为TCDD诱导的交联包膜形成升高的拮抗剂同样有效。棕榈酸视黄酯和阿维A酯作为TCDD拮抗剂效果不太显著。添加氢化可的松可抑制TCDD诱导的角质形成细胞分化。得出的结论是，交联包膜生物量的量化为角质形成细胞分化提供了一个可靠且敏感的参数。在这个体外系统中表明，TCDD强烈诱导从增殖到终末分化的转变，并且这种效应可被视黄酸和视黄醇有效拮抗。
