Havt Alexandre, Schally Andrew V, Halmos Gabor, Varga Jozsef L, Toller Gabor L, Horvath Judit E, Szepeshazi Karoly, Köster Frank, Kovitz Kevin, Groot Kate, Zarandi Marta, Kanashiro Celia A
Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, New Orleans, LA 70112-1262, USA.
Proc Natl Acad Sci U S A. 2005 Nov 29;102(48):17424-9. doi: 10.1073/pnas.0506844102. Epub 2005 Nov 18.
Various attempts to detect human pituitary growth hormone-releasing hormone receptor (pGHRH-R) in neoplastic extrapituitary tissues have thus far failed. Recently, four splice variants (SVs) of GHRH-R have been described, of which SV1 has the highest structural homology to pGHRH-R and likely plays a role in tumor growth. The aim of this study was to reinvestigate whether human tumors and normal human extrapituitary tissues express the pGHRH-R and to corroborate our previous findings on its SVs. Thus, we developed a real-time PCR method for the detection of the mRNA for the pGHRH-R, its SVs, and the GHRH peptide. Using real-time PCR, Western blotting, and radioligand-binding assays, we detected the mRNA for pGHRH-R and pGHRH-R protein in various human cancer cell lines grown in nude mice and in surgical specimens of human lung cancers. The expression of mRNA for SVs of pGHRH-R and GHRH was likewise found in xenografts of human non-Hodgkin's lymphomas, pancreatic cancer, glioblastoma, small-cell lung carcinomas, and in human nonmalignant prostate, liver, lung, kidney, and pituitary. Western blots showed that these normal and malignant human tissues contain SV1 protein and immunoreactive GHRH. Our results demonstrate that some normal human tissues and tumors express mRNA and protein for the pGHRH-R and its splice variants. These findings confirm and extend the concept that GHRH and its receptors play an important role in the pathophysiology of human cancers.
迄今为止，在垂体外肿瘤组织中检测人类垂体生长激素释放激素受体（pGHRH-R）的各种尝试均告失败。最近，已描述了生长激素释放激素受体（GHRH-R）的四种剪接变体（SVs），其中SV1与pGHRH-R具有最高的结构同源性，并且可能在肿瘤生长中起作用。本研究的目的是重新研究人类肿瘤和正常垂体外组织是否表达pGHRH-R，并证实我们先前关于其剪接变体的发现。因此，我们开发了一种实时PCR方法，用于检测pGHRH-R、其剪接变体和生长激素释放激素（GHRH）肽的mRNA。使用实时PCR、蛋白质免疫印迹和放射性配体结合试验，我们在裸鼠体内生长的各种人类癌细胞系以及人类肺癌手术标本中检测到了pGHRH-R的mRNA和pGHRH-R蛋白。在人类非霍奇金淋巴瘤、胰腺癌、胶质母细胞瘤、小细胞肺癌的异种移植瘤以及人类非恶性前列腺、肝脏、肺、肾脏和垂体中同样发现了pGHRH-R剪接变体和GHRH的mRNA表达。蛋白质免疫印迹显示，这些正常和恶性人类组织含有SV1蛋白和免疫反应性GHRH。我们的结果表明，一些正常人类组织和肿瘤表达pGHRH-R及其剪接变体的mRNA和蛋白质。这些发现证实并扩展了生长激素释放激素及其受体在人类癌症病理生理学中起重要作用的概念。
