The expression of the pituitary growth hormone-releasing hormone receptor and its splice variants in normal and neoplastic human tissues

Abstract

Various attempts to detect human pituitary growth hormonereleasing 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, smallcell 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.

Triple-negative breast cancers express receptors for growth hormone-releasing hormone (GHRH) and respond to GHRH antagonists with growth inhibition

“…The primers for the amplification of GHRH were (sense: 5 0 ATG CAG ATG CCA TCT TCA CCA A 3 0 ; antisense: 5 0 TGC TGT CTA CCT GAC GAC CAA 3 0 ), the pituitary GHRH-R (pit-GHRH-R) (sense: 5 0 ATG GGC TGC TGT GCT GGC CAA C 3 0 ; antisense: 5 0 CAC GTG CCA GTG AAG AGC ACG G 3 0 ) and the SV1 receptor (sense: 5 0 TGG GGA GAG GGA AGG AGT TGT 3 0 ; antisense: 5 0 GCG AGA ACC AGC CAC CAG AA 3 0 ), as previously published by Havt et al [40] or Rekasi et al [33]. PCR was performed by 40 cycles of 15 s at 95°C, 10 s at the annealing temperature of 66°C for pit-GHRH-R and SV1 or 59°C for GHRH followed by 20 s at 72°C.…”

Epigenetics and the plasticity of differentiation in normal and cancer stem cells

“…For example, EZH2 is overexpressed in prostate cancer (Varambally et al, 2002) whereas it normally shows preferential expression in hematopoietic tissue and testis. GHRH that encodes growth hormone releasing hormone is overexpressed in various types of cancer including non-Hodgkin lymphoma (Havt et al, 2005) whereas it normally shows preferential expression in the pituitary and to a lesser extent in kidney and liver. DCD is overexpressed in invasive breast carcinoma (Porter et al, 2003), L1CAM is overexpressed in colon cancer (Gavert et al, 2005) and in the colon cancer cell line SW480 (Lotem et al, 2005), SYNUCLEIN GAMMA is overexpressed in many cancers due to hypomethylation of its promoter (Gupta et al, 2003;Liu et al, 2005) and TRKB is overexpressed in many cancers (Geiger and Peeper, 2005), whereas they normally show preferential expression in brain.…”

Antagonists of growth hormone-releasing hormone inhibit growth of androgen-independent prostate cancer through inactivation of ERK and Akt kinases

“…In turn, GH stimulates the production of hepatic insulin-like growth factor I (IGF-I), which is a potent mitogen for many cancers (7). GHRH and its pituitary-type receptor, as well as truncated splice variants (SV) of GHRH receptors, are expressed in various normal human tissues including prostate, kidney, lung, and liver (8), and on many human cancer cell lines and tumors (6,9). Pituitary-type GHRH-R and SV1 appear to mediate the direct effects of GHRH and its antagonistic analogs on tumors (10).…”