Panetta R, Patel Y C
Fraser Laboratories, Department of Medicine, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada.
Life Sci. 1995;56(5):333-42. doi: 10.1016/0024-3205(94)00956-2.
Expression of mRNA for hSSTR1-5 was determined in secretory (GH, PRL, TSH, ACTH) and nonsecretory pituitary tumors, as well as normal human fetal and adult pituitary by reverse transcriptase (RT) PCR followed by Southern blots. All 5 hSSTR subtype mRNAs were expressed in fetal pituitary, while adult pituitary was positive for 4 subtypes, lacking hSSTR4 mRNA. All 15 tumors analyzed were positive for SSTR mRNA, 14 expressing more than one subtype. SSTR2 mRNA in all tissues was expressed as the 2A variant, there being no detectable transcript for SSTR2B. Amongst the 5 SSTRs, mRNA for SSTR2A was the most frequently expressed (87% of tumors) followed by SSTR1 (73%), SSTR3 (53%), SSTR5 (47%), and SSTR4 (40%). The frequency and pattern of expression of the SSTR mRNAs was virtually identical in the different tumor subclasses and did not correlate with tumor size. Since pituitary tumors are monoclonal in origin, multiple SSTR genes are expressed in individual cells. Most tumors are rich in SSTR1 and SSTR2A mRNA compared to the other subtypes. This implies that SST analogs like SMS 201-995, known to interact with SSTR2A, but not with SSTR1, act on pituitary tumors mainly via the SSTR2 subtype.
采用逆转录（RT）PCR 随后进行 Southern 印迹法，测定了人 SSTR1 - 5 的 mRNA 在分泌性（生长激素、催乳素、促甲状腺激素、促肾上腺皮质激素）和非分泌性垂体肿瘤以及正常人类胎儿和成人垂体中的表达情况。所有 5 种 hSSTR 亚型的 mRNA 在胎儿垂体中均有表达，而成人垂体中 4 种亚型呈阳性，缺乏 hSSTR4 mRNA。所分析的 15 个肿瘤中 SSTR mRNA 均呈阳性，14 个表达一种以上亚型。所有组织中的 SSTR2 mRNA 均以 2A 变体形式表达，未检测到 SSTR2B 的转录本。在 5 种 SSTR 中，SSTR2A 的 mRNA 表达最为频繁（87%的肿瘤），其次是 SSTR1（73%）、SSTR3（53%）、SSTR5（47%）和 SSTR4（40%）。SSTR mRNA 的表达频率和模式在不同肿瘤亚类中几乎相同，且与肿瘤大小无关。由于垂体肿瘤起源于单克隆，多个 SSTR 基因在单个细胞中表达。与其他亚型相比，大多数肿瘤富含 SSTR1 和 SSTR2A mRNA。这意味着像 SMS 201 - 995 这样已知与 SSTR2A 相互作用但不与 SSTR1 相互作用的生长抑素类似物，主要通过 SSTR2 亚型作用于垂体肿瘤。
