Aylwin S J, King A, Blenke A, Geddes J F, Wood D F, Monson J P, Burrin J M
Department of Endocrinology, St Bartholomew's and the Royal London School of Medicine and Dentistry, UK.
Eur J Endocrinol. 1998 Oct;139(4):378-86. doi: 10.1530/eje.0.1390378.
GH-secreting pituitary adenomas frequently co-secrete prolactin and glycoprotein hormone alpha-subunit (alphaSU), but expression of additional hormones is considered unusual. The aim of this study was to establish the frequency with which acromegalic tumours secrete intact glycoprotein hormones LH, FSH and TSH, in comparison with other types of pituitary adenoma.
Pituitary tumours were studied by cell culture, measuring the basal secretion of anterior pituitary hormones in vitro. Light microscopy was used to exclude tumours where normal pituitary tissue was present, and immunocytochemistry was employed to confirm the clinical diagnosis and for comparison with tissue culture data.
TSH secretion was observed in vitro in 15/23 somatotroph adenomas, but from only 1/8 lactotroph, 4/29 null cell, 2/12 gonadotroph and 1/10 corticotroph adenomas; moreover, somatotroph adenomas secreted the largest amounts of TSH (P < 0.(001). Somatotroph adenomas also secreted LH (7/23) and FSH (2/23) but less frequently than gonadotroph adenomas. Immunocytochemistry demonstrated glycoprotein expression in somatotroph adenomas (LHbeta: 13%, FSHbeta: 26%, TSHbeta: 30%, alphaSU: 46%) more frequently than in lactotroph, corticotroph and null cell adenomas. A strong correlation was found between alphaSU secretion and TSH secretion in somatotroph adenomas (rho= 0.683, P < 0.001.
TSHbeta is frequently expressed by somatotroph adenomas, often associated with alphaSU expression. Both GH and TSHbeta are dependent on the transcription factor, Pit-1, which is frequently expressed in somatotroph adenomas, although the expression of alphaSU requires an alternative explanation. Increased expression of alphaSU compared with TSHbeta may account for the secretion of free alphaSU by somatotroph adenomas.
生长激素分泌型垂体腺瘤常同时分泌催乳素和糖蛋白激素α亚基（αSU），但分泌其他激素的情况被认为不常见。本研究的目的是确定与其他类型垂体腺瘤相比，肢端肥大症肿瘤分泌完整糖蛋白激素促黄体生成素（LH）、促卵泡生成素（FSH）和促甲状腺激素（TSH）的频率。
通过细胞培养研究垂体肿瘤，测量体外垂体前叶激素的基础分泌。用光学显微镜排除存在正常垂体组织的肿瘤，并采用免疫细胞化学方法确认临床诊断并与组织培养数据进行比较。
在23例生长激素细胞腺瘤中有15例在体外观察到TSH分泌，但在8例催乳素细胞腺瘤中仅1例、29例无功能细胞腺瘤中4例、12例促性腺激素细胞腺瘤中2例以及10例促肾上腺皮质激素细胞腺瘤中1例观察到TSH分泌；此外，生长激素细胞腺瘤分泌的TSH量最大（P<0.001）。生长激素细胞腺瘤也分泌LH（23例中的7例）和FSH（23例中的2例），但频率低于促性腺激素细胞腺瘤。免疫细胞化学显示生长激素细胞腺瘤中糖蛋白表达（LHβ：13%，FSHβ：26%，TSHβ：30%，αSU：46%）比催乳素细胞、促肾上腺皮质激素细胞和无功能细胞腺瘤更频繁。在生长激素细胞腺瘤中发现αSU分泌与TSH分泌之间存在强相关性（ρ=0.683，P<0.001）。
生长激素细胞腺瘤常表达TSHβ，且常与αSU表达相关。生长激素（GH）和TSHβ均依赖转录因子Pit-1，Pit-1在生长激素细胞腺瘤中常表达，尽管αSU的表达需要另作解释。与TSHβ相比，αSU表达增加可能解释了生长激素细胞腺瘤分泌游离αSU的现象。
