Greenman Y, Melmed S
Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California 90048-1865.
J Clin Endocrinol Metab. 1994 Sep;79(3):724-9. doi: 10.1210/jcem.79.3.7521350.
The expression of three somatostatin receptor subtypes, SSTR3, SSTR4, and SSTR5, was evaluated in 33 pituitary tumor specimens. SSTR3 expression was studied by reverse transcription coupled to polymerase chain reaction, whereas SSTR4 and SSTR5 expression was determined by ribonuclease protection assay. SSTR3 was expressed in 6 of 7 GH-secreting tumors, all 8 clinically nonfunctioning tumors, all 3 prolactinomas, and 1 of 2 ACTH-secreting tumors tested. Eight nonfunctioning adenomas had undetectable messenger ribonucleic acid levels of SSTR4, and only 1 of them expressed SSTR5. SSTR4 expression was also undetectable in 11 GH-secreting tumors, 3 prolactinomas, and 1 ACTH-secreting tumor tested. In contrast, SSTR5 was highly expressed in 10 of 11 GH-secreting adenomas and 1 prolactinoma. Two prolactinomas and 1 ACTH-secreting tumor had low levels of expression of SSTR5. The widespread pituitary adenoma expression of SSTR3, regardless of hormonal secretory type, suggests that SSTR3 might be involved in a somatostatin action(s) other than GH or TSH regulation. SSTR5 is expressed predominantly in mammosomatotroph-derived tumors, suggesting that this receptor subtype may be an important determinant of GH secretion in acromegaly.
在33例垂体肿瘤标本中评估了三种生长抑素受体亚型SSTR3、SSTR4和SSTR5的表达。通过逆转录聚合酶链反应研究SSTR3的表达，而SSTR4和SSTR5的表达通过核糖核酸酶保护试验确定。在所检测的7例生长激素分泌性肿瘤中的6例、所有8例临床无功能肿瘤、所有3例催乳素瘤以及2例促肾上腺皮质激素分泌性肿瘤中的1例中表达了SSTR3。8例无功能腺瘤的SSTR4信使核糖核酸水平检测不到，其中只有1例表达SSTR5。在所检测的11例生长激素分泌性肿瘤、3例催乳素瘤和1例促肾上腺皮质激素分泌性肿瘤中也检测不到SSTR4的表达。相比之下，SSTR5在11例生长激素分泌性腺瘤中的10例和1例催乳素瘤中高表达。2例催乳素瘤和1例促肾上腺皮质激素分泌性肿瘤的SSTR5表达水平较低。无论激素分泌类型如何，SSTR3在垂体腺瘤中广泛表达，这表明SSTR3可能参与了生长激素或促甲状腺激素调节以外的生长抑素作用。SSTR5主要在乳腺生长激素细胞来源的肿瘤中表达，这表明该受体亚型可能是肢端肥大症中生长激素分泌的重要决定因素。
