Fritsch M, Orfanos C E, Zouboulis C C
Department of Dermatology, University Medical Center Benjamin Franklin, The Free University of Berlin, Berlin, Germany.
J Invest Dermatol. 2001 May;116(5):793-800. doi: 10.1046/j.1523-1747.2001.01312.x.
The mRNA expression patterns of the androgen receptor and the androgen metabolizing enzymes 3beta-hydroxysteroid dehydrogenase/Delta(5-4)-isomerase, 17beta-hydroxysteroid dehydrogenase, 5alpha-reductase, and 3alpha-hydroxysteroid dehydrogenase were investigated in three different cell populations originating from human skin, SZ95 sebocytes, HaCaT keratinocytes, and MeWo melanoma cells, by means of reverse transcription polymerase chain reaction. Restriction analysis of cDNA fragments was performed to identify isozymes of 3beta-hydroxysteroid dehydrogenase/Delta(5-4)-isomerase and 3alpha-hydroxysteroid dehydrogenase. In addition, 3H-dihydroepiandrosterone and 3H-testosterone were used as substrates to determine the metabolic activity of these enzymes in SZ95 sebocytes, primary sebocyte cultures, and HaCaT keratinocytes. Furthermore, the effects of the selective 5alpha-reductase type 1 and 2 inhibitors, 4,7beta-dimethyl-4-aza-5alpha-cholestan-3-one and dihydrofinasteride, respectively, and of the 3beta-hydroxysteroid dehydrogenase/Delta(5-4)-isomerase inhibitor cyproterone acetate on androgen metabolism were investigated. Androgen receptor mRNA was detected in SZ95 sebocytes and HaCaT keratinocytes but not in MeWo melanoma cells, whereas 3beta-hydroxysteroid dehydrogenase/Delta(5-4)-isomerase isotype 1 mRNA and metabolic activity were only found in SZ95 sebocytes. The enzyme activity could be inhibited by cyproterone acetate. Type 2 17beta-hydroxysteroid dehydrogenase, type 1 5alpha-reductase, and 3alpha-hydroxysteroid dehydrogenase mRNA were expressed in all three cell populations tested, whereas type 3 17beta-hydroxysteroid dehydrogenase mRNA could only be detected in SZ95 sebocytes. The major metabolic steps of testosterone in SZ95 sebocytes, primary sebocyte cultures, and HaCaT keratinocytes were its conversion to androstenedione by 17beta-hydroxysteroid dehydrogenase and further to 5alpha-androstanedione by 5alpha-reductase. The type 1 5alpha-reductase selective inhibitor 4,7beta-dimethyl-4-aza-5alpha-cholestan-3-one, but not the type 2 selective inhibitor dihydrofinasteride, inhibited 5alpha-reductase at low concentrations in SZ95 sebocytes and HaCaT keratinocytes. 5alpha-androstanedione was degraded to androsterone by 3alpha-hydroxysteroid dehydrogenase, which exhibited a stronger activity in HaCaT keratinocytes than in SZ95 sebocytes and in primary sebocyte cultures. Lower levels of 5alpha-dihydrotestosterone and 5alpha-androstanediol were also detected in all cells tested. Our investigations show that specific enzyme expression and activity in cultured sebocytes and keratinocytes seem to allocate different duties to these cells in vitro. Sebocytes are able to synthesize testosterone from adrenal precursors and to inactivate it in order to maintain androgen homeostasis, whereas keratinocytes are responsible for androgen degradation.
通过逆转录聚合酶链反应，研究了雄激素受体以及雄激素代谢酶3β-羟基类固醇脱氢酶/Δ⁵⁻⁴异构酶、17β-羟基类固醇脱氢酶、5α-还原酶和3α-羟基类固醇脱氢酶在源自人皮肤的三种不同细胞群体（SZ95皮脂腺细胞、HaCaT角质形成细胞和MeWo黑色素瘤细胞）中的mRNA表达模式。对cDNA片段进行限制性分析，以鉴定3β-羟基类固醇脱氢酶/Δ⁵⁻⁴异构酶和3α-羟基类固醇脱氢酶的同工酶。此外，使用³H-脱氢表雄酮和³H-睾酮作为底物，测定这些酶在SZ95皮脂腺细胞、原代皮脂腺细胞培养物和HaCaT角质形成细胞中的代谢活性。此外，还研究了选择性1型和2型5α-还原酶抑制剂（分别为4,7β-二甲基-4-氮杂-5α-胆甾烷-3-酮和度他雄胺）以及3β-羟基类固醇脱氢酶/Δ⁵⁻⁴异构酶抑制剂醋酸环丙孕酮对雄激素代谢的影响。在SZ95皮脂腺细胞和HaCaT角质形成细胞中检测到雄激素受体mRNA，但在MeWo黑色素瘤细胞中未检测到，而仅在SZ95皮脂腺细胞中发现3β-羟基类固醇脱氢酶/Δ⁵⁻⁴异构酶1型mRNA和代谢活性。醋酸环丙孕酮可抑制该酶活性。2型十七β-羟基类固醇脱氢酶、1型5α-还原酶和3α-羟基类固醇脱氢酶mRNA在所有测试的三种细胞群体中均有表达，而3型十七β-羟基类固醇脱氢酶mRNA仅在SZ95皮脂腺细胞中可检测到。在SZ95皮脂腺细胞、原代皮脂腺细胞培养物和HaCaT角质形成细胞中，睾酮的主要代谢步骤是通过17β-羟基类固醇脱氢酶将其转化为雄烯二酮，并进一步通过α-还原酶转化为5α-雄烷二酮。1型5α-还原酶选择性抑制剂4,7β-二甲基-4-氮杂-5α-胆甾烷-3-酮在低浓度下可抑制SZ95皮脂腺细胞和HaCaT角质形成细胞中的5α-还原酶，而2型选择性抑制剂度他雄胺则无此作用。5α-雄烷二酮通过3α-羟基类固醇脱氢酶降解为雄酮，该酶在HaCaT角质形成细胞中的活性比在SZ95皮脂腺细胞和原代皮脂腺细胞培养物中更强。在所有测试细胞中也检测到较低水平的5α-双氢睾酮和5α-雄烷二醇。我们的研究表明，培养的皮脂腺细胞和角质形成细胞中的特定酶表达和活性似乎在体外赋予了这些细胞不同的职责。皮脂腺细胞能够从肾上腺前体合成睾酮并使其失活，以维持雄激素稳态，而角质形成细胞则负责雄激素的降解。
