Human renal cell carcinoma expresses distinct binding sites for growth hormone-releasing hormone

Halmos, Gábor; Schally, Andrew V.; Varga, József; Płonowski, Artur; Rékási, Zoltán; Czömpöly, Tamás

doi:10.1073/pnas.180313097

Cited by 85 publications

(123 citation statements)

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“…32. Preparation of the membrane fractions from the tumor samples was carried out as reported (17,25). Binding sites for GHRH were determined by in vitro ligand competition assays based on the binding of radiolabeled JV-1-42 to tumor membrane fractions (17,25).…”

Section: Methodsmentioning

confidence: 99%

“…We then reported the expression of four splice variants (SVs) of the full-length human GHRH-R in normal tissues and certain cancer cell lines on the basis of sequence analyses of cDNA encoding these receptors (16,17). The deduced amino acid sequence of one of these SVs , called SV 1 , shows a close similarity to that of the full-length GHRH.…”

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confidence: 99%

“…The expression of the mRNA for SV 1 has been detected, along with high-affinity binding sites for the radiolabeled GHRH antagonist JV-1-42, on a wide variety of human cancers, including gastroenteropancreatic, renal, lung, and prostatic tumor cell lines and surgical specimens of human prostate cancer (22)(23)(24)(25). A comparison of the binding characteristics of GHRH, VIP, pituitary adenylate cyclase-activating polypeptide, and GHRH antagonists revealed that GHRH antagonists bind more powerfully to the membrane fraction of CAKI-I human renal cell adenocarcinoma than to the other peptides (17). High affinity of the antagonists to the tumoral receptor facilitates their selective uptake from the circulation onto the tumor tissue (17,24).…”

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confidence: 99%

“…A comparison of the binding characteristics of GHRH, VIP, pituitary adenylate cyclase-activating polypeptide, and GHRH antagonists revealed that GHRH antagonists bind more powerfully to the membrane fraction of CAKI-I human renal cell adenocarcinoma than to the other peptides (17). High affinity of the antagonists to the tumoral receptor facilitates their selective uptake from the circulation onto the tumor tissue (17,24). In addition, GHRH increased the proliferation of NIH 3T3 mouse fibroblasts transfected with the plasmid expressing the mRNA for SV 1 , and this effect was inhibited by the GHRH antagonist JV-1-38 in a dose-dependent manner (26).…”

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Development of a polyclonal antiserum for the detection of the isoforms of the receptors for human growth hormone-releasing hormone on tumors

Toller

Horváth

Schally

et al. 2004

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

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Antagonists of growth hormone-releasing hormone (GHRH) inhibit the growth of various human cancers by multiple mechanisms, which include direct effects on tumor cells through the splice variants (SV) of the GHRH receptor. Our findings suggest that the tumoral protein encoded by SV 1 (SV 1) is a likely functional receptor. The aim of this study was to develop a polyclonal antiserum against a polypeptide analog of segment 1-25 of the putative SV 1 receptor protein. Rabbits were immunized with [Ala-23]SV 1 (1-25)-Tyr-26-Cys-27-NH2 as a hapten, conjugated to BSA or keyhole limpet hemocyanin. The antisera thus generated were evaluated by RIA for binding to the radiolabeled hapten. The specificity and sensitivity of the antisera were studied on xenografts of RL and HT human non-Hodgkin's lymphomas. The sera raised against keyhole limpet hemocyanin-SV 1 hapten, showed binding values of 50 -75% at a 1:56,000 dilution. In Western blot analyses, the purified polyclonal antibody recognized a specific signal with a molecular mass of Ϸ40 kDa in RL and HT lymphomas. This band corresponds to the estimated molecular mass of the GHRH receptor isoform encoded by SV 1. RT-PCR and ligand binding studies also revealed the expression of SV 1 and the presence of high-affinity binding sites for GHRH on RL and HT tumors. Because the antiserum developed recognizes the tumoral GHRH receptor protein encoded by SV 1, it should be of value in various investigations.splice variant ͉ growth hormone-releasing hormone receptor ͉ polyclonal antibody ͉ non-Hodgkin's lymphoma A ntagonists of growth hormone-releasing hormone (GHRH) inhibit the growth of experimental human cancer cell lines xenografted into nude mice or cultured in vitro and are being developed for cancer therapy (1-4). To design still more potent antagonists, we have to fully understand their mechanism of action. GHRH antagonists suppress tumor growth through indirect and direct pathways. The indirect mechanism operates through a suppression of the growth hormone release from the pituitary and the resulting inhibition of the production of insulin-like growth factor I in the liver (1-11). However, the principal action of GHRH antagonists is probably exerted directly on tumors and appears to be mediated by specific receptors for GHRH antagonists on cancer cells (1-9, 11-13). Although the mRNA for GHRH and immunologically active GHRH were demonstrated in various human tumor cells, the mRNA for human pituitary GHRH receptor (GHRH-R) has not been detected on these tumor cells or any of the other cancer models (11,14,15).Because of the structural similarities between GHRH and vasoactive intestinal peptide (VIP), the receptors for VIP could be a target for the GHRH antagonists, but GHRH antagonists inhibit the proliferation of MiaPaCa-2 human pancreatic tumor cells, which do not express the receptors for VIP (13). Moreover, in LNCaP human prostatic carcinoma cells, which are positive for the VIP receptors, GHRH antagonists inhibit tumor growth more powerfully than the antagonists of VIP (1...

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Section: Methodsmentioning

confidence: 99%

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Development of a polyclonal antiserum for the detection of the isoforms of the receptors for human growth hormone-releasing hormone on tumors

Toller

Horváth

Schally

et al. 2004

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

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“…Accordingly, the expression of mRNA for GHRH or its peptide product were detected in surgical specimens of human endometrial, ovarian, breast and prostatic cancers [27,31,32]. mRNAs encoding four splice variants (SV) of GHRH receptors and specific high affinity binding sites for GHRH and its antagonistic analogs have been identified in diverse cell lines and specimens of human cancers [19,20,24,25,28,29,31,[33][34][35][36]. These findings suggest that the direct antiproliferative action of GHRH antagonists could be exerted through the disruption of an autocrine/paracrine stimulatory loop formed by tumoral GHRH and its receptors on tumors [14,19,20,28,29,35,37,38].…”

Section: Introductionmentioning

confidence: 99%