Ligand-dependent and -independent effects of splice variant 1 of growth hormone-releasing hormone receptor

Kiaris, Hippokratis; Chatzistamou, Ioulia; Schally, Andrew V.; Halmos, Gábor; Varga, József; Koutselini, Helen; Kalofoutis, Anastasios

doi:10.1073/pnas.1533185100

Cited by 60 publications

(58 citation statements)

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“…The T47D cell line has the highest expression of SV-1 of the GHRH receptor with its ligand-dependent and independent activity. The inhibition of the gene expression for GHRH in T47D breast cancer cell line did not have the potent antiproliferative effect found in the other two breast cancer cell lines (MDA-MB-468 and MDA-MB-435S), possibly because the ligand independent activity of the SV1 continued to enhance the proliferation rate of the T47D cells (Kiaris et al, 2003;Barabutis et al, 2007).…”

Section: Discussionmentioning

confidence: 79%

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Knocking down gene expression for growth hormone-releasing hormone inhibits proliferation of human cancer cell lines

Barabutis

Schally

2008

Br J Cancer

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Splice Variant 1 (SV-1) of growth hormone-releasing hormone (GHRH) receptor, found in a wide range of human cancers and established human cancer cell lines, is a functional receptor with ligand-dependent and independent activity. In the present study, we demonstrated by western blots the presence of the SV1 of GHRH receptor and the production of GHRH in MDA-MB-468, MDA-MB-435S and T47D human breast cancer cell lines, LNCaP prostate cancer cell line as well as in NCI H838 non-small cell lung carcinoma. We have also shown that GHRH produced in the conditioned media of these cell lines is biologically active. We then inhibited the intrinsic production of GHRH in these cancer cell lines using si-RNA, specially designed for human GHRH. The knocking down of the GHRH gene expression suppressed the proliferation of T47D, MDA-MB-435S, MDA-MB-468 breast cancer, LNCaP prostate cancer and NCI H838 non-SCLC cell lines in vitro. However, the replacement of the knocked down GHRH expression by exogenous GHRH (1 -29)NH 2 re-established the proliferation of the silenced cancer cell lines. Furthermore, the proliferation rate of untransfected cancer cell lines could be stimulated by GHRH (1 -29)NH 2 and inhibited by GHRH antagonists MZ-5-156, MZ-4-71 and JMR-132. These results extend previous findings on the critical function of GHRH in tumorigenesis and support the role of GHRH as a tumour growth factor.

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Section: Discussionmentioning

confidence: 79%

“…Some tumours also express pituitary type of GHRH receptor Christodoulou et al, 2006). Besides its ligand-dependent activity, a ligand-independent activity of SV1 has also been demonstrated (Kiaris et al, 2003). A recent study showed the stimulation and proliferation of MCF-7 breast cancer cells after the transfection of SV1 (Barabutis et al, 2007).…”

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confidence: 99%

Knocking down gene expression for growth hormone-releasing hormone inhibits proliferation of human cancer cell lines

Barabutis

Schally

2008

Br J Cancer

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“…nlm.nih.gov). However, previous studies showed that the immunostaining of HEC-1A human endometrial cancer cells was abolished when the expression of SV1 was ablated by SV1-antisense RNA (32). Moreover, MDA-MB-231 human breast cancer cells that do not express SVs did not show corresponding protein bands in the Western blots, whereas RL and HT lymphomas presented a predicted protein of 40 kDa, which would also correspond to SV1 (25).…”

Section: Discussionmentioning

confidence: 85%

“…This method consisted of two consecutive PCR reactions that could accomplish the amplification of cDNA for all four SVs at the sizes of 720, 566, 390, and 335 bp corresponding to SV1, SV2, SV3, and SV4, respectively (18,22,23). Even though SV1 is the only SV of GHRH-R that was proven to respond physiologically to GHRH binding (31,32), we recently established a protocol that could detect the expression of each SV separately, without using the method of nested PCR. Nonetheless, our main objective was to determine whether the mRNA and protein for the pGHRH-R could be expressed in some tumor tissues.…”

Section: Discussionmentioning

confidence: 99%

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

Havt

Schally

Halmos

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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109

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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.

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“…This concept is supported by the demonstration by our group of the presence of GHRH-R and truncated splice variants of GHRH-R (SV-1-4) in non-malignant human tissues, various human cancer cell lines and human prostate cancer specimens (3)(4)(5)(6). Of the four truncated receptors, SV-1 has the greatest structural similarity to GHRH-R and is probably the main receptor that mediates the effects of GHRH and its antagonists in tumours (7)(8)(9). In the present study, we investigated the expression of GHRH-R, SV-1, SV-2 and SV-4 in normal and malignant human tissues of the gastrointestinal tract by means of immunohistochemistry and mRNA analyses.…”

Section: Introductionmentioning

confidence: 89%

Differential expression of GHRH receptor and its splice variant 1 in human normal and malignant mucosa of the oesophagus and colon

Hohla

Moder²,

Mayrhauser³

et al. 2008

Int J Oncol

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Abstract. Recent evidence indicates that growth hormonereleasing hormone (GHRH) functions as a growth factor for gastrointestinal (GI) tumours. The tumourigenic effects of GHRH appear to be mediated by the splice variant 1 (SV-1) of GHRH receptor as well as the full length pituitary type receptor for GHRH (GHRH-R). We examined the protein and mRNA expression of GHRH-R and SV-1 in normal human tissues and tumours of the gastrointestinal (GI-) tract by immunohistochemical staining and reverse transcriptase (RT)-PCR. Squamous cells and squamous cell carcinoma of the oesophagus were negative for GHRH-R and SV-1, while Barrett's mucosa and adenocarcinomas of the oesophagus showed a strong expression of both receptors. The expression of GHRH-R was absent in normal colonic mucosa other than neuroendocrine cells (NE) and lining epithelium (LE) but strong in tubular adenomas of the colon, while the staining for SV-1 was absent in cells other than NE. However, the expression of both receptors was significantly increased in tubulovillous adenomas and colorectal cancers. No differences were seen in protein levels for both receptors between normal and neoplastic tissues of the stomach, pancreas and liver. Because of low mRNA levels for both receptors in all samples tested, only a qualitative assessment could be made. However, mRNA for GHRH-R and SV-1 showed a nearperfect correlation with the assessment of receptor proteins by immunostaining. Our study shows that in contrast to normal mucosa, transformed mucosa of the oesophagus and the colon expresses GHRH-R and SV-1. This aberrant expression of GHRH-R and SV-1 in oesophageal and colorectal malignancies may provide a molecular target for a therapeutic approach based on GHRH antagonists.

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Ligand-dependent and -independent effects of splice variant 1 of growth hormone-releasing hormone receptor

Cited by 60 publications

References 50 publications

Knocking down gene expression for growth hormone-releasing hormone inhibits proliferation of human cancer cell lines

Knocking down gene expression for growth hormone-releasing hormone inhibits proliferation of human cancer cell lines

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

Differential expression of GHRH receptor and its splice variant 1 in human normal and malignant mucosa of the oesophagus and colon

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