1
|
Chang C, Varamini P, Giddam AK, Mansfeld FM, D'Occhio MJ, Toth I. Investigation of Structure-Activity Relationships of Synthetic Anti-Gonadotropin Releasing Hormone Vaccine Candidates. ChemMedChem 2015; 10:901-10. [DOI: 10.1002/cmdc.201500036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Indexed: 11/05/2022]
|
2
|
Aguilar FF, Barranco JJ, Fuentes EB, Aguilera LC, Sáez YL, Santana MDC, Vázquez EP, Baker RB, Acosta OR, Pérez HG, Nieto GG. Very small size proteoliposomes (VSSP) and Montanide combination enhance the humoral immuno response in a GnRH based vaccine directed to prostate cancer. Vaccine 2012; 30:6595-9. [PMID: 22921738 DOI: 10.1016/j.vaccine.2012.08.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 08/09/2012] [Accepted: 08/11/2012] [Indexed: 11/24/2022]
Abstract
Very small size proteoliposomes (VSSP) constitute a complex of very small size proteoliposomes that includes proteins, lipids, CpG and gangliosides tumor-associated that provides a potential target for cancer immunotherapy. This compound has been described to stimulate the humoral and cellular response, dendritic cells (DC) activation and differentiation of T-helper cells, specially, in immunocompromised patients with cancer status. This work deals with the stimulating capacity of the VSSP to reach a humoral response when they are used as a component in a peptidic vaccine based on the gonadotrophin releasing hormone (GnRH). This study was carried out in male Copenhagen rats, which were immunized with 750μg of the GnRH mimetic peptide (GnRHm1-TT) with or without the VSSP. The mixtures were always emulsified with the oil adjuvant Montanide ISA 51. The anti GnRH seroconversion analysis revealed that the group immunized with the peptide GnRHm1-TT/VSSP developed a strong anti GnRH seroconversion. These antibody levels proved to be significant superior to those reached by the use of the GnRHm1-TT peptide solely emulsified in Montanide. Post-mortem analysis on the Testosterone ablation target organs (prostate and testicles) yielded a sudden decrease in their size and weight in respect to the control group. On the other hand, the group submitted to the use of GnRHm1-TT/VSSP, showed a significant difference in the reduction of these target organs in comparison with the group only immunized with GnRHm1-TT adjuvated in Montanide ISA 51. These values turned to be of p=0.023 and p=0.009 in the prostate and testicles respectively. These findings foreground the VSSP as a useful immunopotentiator to be used as part of a GnRH based vaccine to treat prostate cancer.
Collapse
|
3
|
Harris GL, Creason MB, Brulte GB, Herr DR. In vitro and in vivo antagonism of a G protein-coupled receptor (S1P3) with a novel blocking monoclonal antibody. PLoS One 2012; 7:e35129. [PMID: 22496900 PMCID: PMC3320623 DOI: 10.1371/journal.pone.0035129] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 03/13/2012] [Indexed: 11/24/2022] Open
Abstract
Background S1P3 is a lipid-activated G protein-couple receptor (GPCR) that has been implicated in the pathological processes of a number of diseases, including sepsis and cancer. Currently, there are no available high-affinity, subtype-selective drug compounds that can block activation of S1P3. We have developed a monoclonal antibody (7H9) that specifically recognizes S1P3 and acts as a functional antagonist. Methodology/Principal Findings Specific binding of 7H9 was demonstrated by immunocytochemistry using cells that over-express individual members of the S1P receptor family. We show, in vitro, that 7H9 can inhibit the activation of S1P3-mediated cellular processes, including arrestin translocation, receptor internalization, adenylate cyclase inhibiton, and calcium mobilization. We also demonstrate that 7H9 blocks activation of S1P3 in vivo, 1) by preventing lethality due to systemic inflammation, and 2) by altering the progression of breast tumor xenografts. Conclusions/Significance We have developed the first-reported monoclonal antibody that selectively recognizes a lipid-activated GPCR and blocks functional activity. In addition to serving as a lead drug compound for the treatment of sepsis and breast cancer, it also provides proof of concept for the generation of novel GPCR-specific therapeutic antibodies.
Collapse
Affiliation(s)
- Greg L. Harris
- Expression Drug Designs, LLC, San Marcos, California, United States of America
- Department of Biology, San Diego State University, San Diego, California, United States of America
| | - Michael B. Creason
- Expression Drug Designs, LLC, San Marcos, California, United States of America
| | - Greg B. Brulte
- Expression Drug Designs, LLC, San Marcos, California, United States of America
| | - Deron R. Herr
- Expression Drug Designs, LLC, San Marcos, California, United States of America
- Department of Biology, San Diego State University, San Diego, California, United States of America
- * E-mail:
| |
Collapse
|
4
|
Wang XJ, Gu K, Xu JS, Li MH, Cao RY, Wu J, Li TM, Liu JJ. Immunization with a recombinant GnRH vaccine fused to heat shock protein 65 inhibits mammary tumor growth in vivo. Cancer Immunol Immunother 2010; 59:1859-66. [PMID: 20803011 PMCID: PMC11031030 DOI: 10.1007/s00262-010-0911-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 08/16/2010] [Indexed: 10/19/2022]
Abstract
Gonadotrophin-releasing hormone (GnRH) is the prime decapeptide hormone in the regulation of mammalian reproduction. Active immunization against GnRH has been a good treatment option to fight against hormone-dependent disease such as breast cancer. We designed and purified a novel protein vaccine Hsp65-GnRH(6) containing heat shock protein 65 (Hsp65) and six copies of GnRH in linear alignment. Immunization with Hsp65-GnRH(6) evoked strong humoral response in female mice. The generation of specific anti-GnRH antibodies was detected by ELISA and verified by western blot. In addition, anti-GnRH antibodies effectively neutralized endogenous GnRH activity in vivo, as demonstrated by the degeneration of the ovaries and uteri in the vaccinated mice. Moreover, the growth of EMT-6 mammary tumor allografts was inhibited by anti-GnRH antibodies. Histological examinations have shown that there was increased focal necrosis in tumors. Taken together, our results showed that immunization with Hsp65-GnRH(6) elicited high titer of specific anti-GnRH antibodies and further led to atrophy of reproductive organs. The specific antibodies could inhibit the growth of EMT-6 murine mammary tumor probably via an indirect mechanism that includes the depletion of estrogen. In view of these results, the protein vaccine Hsp65-GnRH(6) appears to be a promising candidate vaccine for hormone-dependent cancer therapy.
Collapse
Affiliation(s)
- Xue Jun Wang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Hanzhong Road 140, Nanjing, 210029 China
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanjing Medical University, Hanzhong Road 140, Nanjing, 210029 China
- Minigene Pharmacy Laboratory, School of Life Science and Technology, China Pharmaceutical University, Tongjia Xiang 24, Nanjing, 210009 China
| | - Kai Gu
- Minigene Pharmacy Laboratory, School of Life Science and Technology, China Pharmaceutical University, Tongjia Xiang 24, Nanjing, 210009 China
| | - Jin Shu Xu
- School of Pharmacy, Nanjing Medical University, Hanzhong Road 140, Nanjing, 210029 China
| | - Ming Hui Li
- Minigene Pharmacy Laboratory, School of Life Science and Technology, China Pharmaceutical University, Tongjia Xiang 24, Nanjing, 210009 China
| | - Rong Yue Cao
- Minigene Pharmacy Laboratory, School of Life Science and Technology, China Pharmaceutical University, Tongjia Xiang 24, Nanjing, 210009 China
| | - Jie Wu
- Minigene Pharmacy Laboratory, School of Life Science and Technology, China Pharmaceutical University, Tongjia Xiang 24, Nanjing, 210009 China
| | - Tai Ming Li
- Minigene Pharmacy Laboratory, School of Life Science and Technology, China Pharmaceutical University, Tongjia Xiang 24, Nanjing, 210009 China
| | - Jing Jing Liu
- Minigene Pharmacy Laboratory, School of Life Science and Technology, China Pharmaceutical University, Tongjia Xiang 24, Nanjing, 210009 China
| |
Collapse
|
5
|
Xu J, Zhu Z, Wu J, Liu W, Shen X, Zhang Y, Hu Z, Zhu D, Roque RS, Liu J. Immunization with a recombinant GnRH vaccine conjugated to heat shock protein 65 inhibits tumor growth in orthotopic prostate cancer mouse model. Cancer Lett 2008; 259:240-50. [DOI: 10.1016/j.canlet.2007.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 10/11/2007] [Accepted: 10/11/2007] [Indexed: 10/22/2022]
|
6
|
Immunotherapy of prostate cancer in a murine model using a novel GnRH based vaccine candidate. Vaccine 2007; 25:8460-8. [PMID: 18022737 DOI: 10.1016/j.vaccine.2007.09.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Revised: 09/14/2007] [Accepted: 09/15/2007] [Indexed: 01/27/2023]
Abstract
Previous studies with gonadotrophin releasing hormone (GnRH/LHRH) vaccines have shown the usefulness of immunization against this hormone in prostate cancer. To this end, we have generated a completely synthetic peptide modified at position 6 and attached to the 830-844 tetanic toxoid (TT) helper T cell sequence. Through this work we have demonstrated that the GnRHm1-TT molecule was highly immunogenic when it is formulated as an oil-based emulsion adjuvated with Montanide ISA 51. That results correlated directly with testosterone reduction and tumor growth inhibition of the Dunning R3327-H androgen responsive prostate tumor model in rats. GnRHm1-TT, proved to be safe and useful for future clinical trials.
Collapse
|
7
|
Xu J, Zhu Z, Duan P, Li W, Zhang Y, Wu J, Hu Z, Roque RS, Liu J. Cloning, expression, and purification of a highly immunogenic recombinant gonadotropin-releasing hormone (GnRH) chimeric peptide. Protein Expr Purif 2006; 50:163-70. [PMID: 17064933 DOI: 10.1016/j.pep.2006.08.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 08/30/2006] [Accepted: 08/31/2006] [Indexed: 11/24/2022]
Abstract
To design an anti-gonadotropin-releasing hormone (GnRH) vaccine capable of eliciting strong immunogenicity, a gene fragment encoding a chimeric peptide was constructed using polymerase chain reaction and ligated into a novel expression vector for recombinant expression in a T7 RNA polymerase-based expression system. The chimeric peptide called GnRH3-hinge-MVP contained three linear repeats of GnRH (GnRH3), a fragment of the human IgG1 hinge region, and a T-cell epitope of measles virus protein (MVP). The expression plasmid contained the GnRH3-hinge-MVP construct ligated to its fusion partner (AnsB-C) via an unique acid labile Asp-Pro linker. The recombinant fusion protein was expressed in an inclusion body in Escherichia coli under IPTG or lactose induction and the target peptide was easily purified using washing of urea and ethanol precipitation. The target chimeric peptide was isolated from the fusion partner following acid hydrolysis and purified using DEAE-Sephacel chromatography. The purified GnRH3-hinge-MVP was determined to be highly homogeneous by IEF analysis and the N-terminal sequencing. Further, immunization of female mice with the recombinant chimeric peptide resulted in generation of high-titer antibodies specific for GnRH. The results showed that GnRH3-hinge-MVP could be considered as a candidate anti-GnRH vaccine.
Collapse
Affiliation(s)
- Jinshu Xu
- The Biopharmaceutical College, China Pharmaceutical University, Nanjing, PR China
| | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Triozzi PL, Bolger GB, Neidhart J, Rinehart JJ, Saleh M, Allen KO, Sellers S, Waddell MJ. Effect of docetaxel chemotherapy on the activity of a gonadotropin releasing hormone vaccine in patients with advanced prostate cancer. Prostate 2005; 65:316-21. [PMID: 16015596 DOI: 10.1002/pros.20295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Gonadotropin releasing hormone (GnRH)-DT vaccine elicits antibody that may inhibit prostate cancers indirectly by blocking GnRH induced gonadotropin release, and consequent androgen synthesis, and directly by immune effector and antiproliferative mechanisms. A pilot study was performed to determine how to best combine GnRH-DT vaccine with potentially immunosuppressive chemotherapy. METHODS Patients with metastatic, hormone-refractory prostate cancer were randomized into either a concurrent cohort, in which they received docetaxel on day 1 of weeks 1, 4, 7, and 10 and GnRH-DT vaccine on day 2 of weeks 1, 3, and 7 or a sequential cohort, in which they received GnRH-DT vaccine on weeks 1, 3, and 7 before beginning docetaxel on week 10. GnRH-DT vaccine was administered intramuscularly. Docetaxel was infused intravenously after pre-medication with high-dose dexamethasone, and infusions repeated every 3 weeks in the absence of toxicity or progressive cancer. RESULTS GnRH-DT vaccine and docetaxel were well tolerated without evidence of significant local or systemic toxicities. Anti-GnRH antibody was elicited in six of six treated concurrently and five of six treated sequentially. The kinetics of antibody induction and the titers of antibody achieved in both treatment cohorts were similar. Anti-GnRH antibody persisted for up to 28 weeks in a patient maintained on docetaxel. CONCLUSION The administration of docetaxel with high-dose dexamethasone does not inhibit the ability of patients with advanced prostate cancer to be immunized with GnRH-DT vaccine.
Collapse
Affiliation(s)
- Pierre L Triozzi
- Comprehensive Cancer Center, The University of Alabama at Birmingham, Birmingham, Alabama 35294-3300, USA.
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Jinshu X, Jingjing L, Duan P, Zheng Z, Ding M, Jie W, Rongyue C, Zhuoyi H, Roque RS. A synthetic gonadotropin-releasing hormone (GnRH) vaccine for control of fertility and hormone dependent diseases without any adjuvant. Vaccine 2005; 23:4834-43. [PMID: 15996796 DOI: 10.1016/j.vaccine.2005.05.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Accepted: 05/16/2005] [Indexed: 11/22/2022]
Abstract
Active immunization against self-peptides have gained widespread acceptance inspite of their low immunogenicity. Recent applications involving multiple copies of self-peptides in linear alignment and conjugation with carrier proteins appear to increase the immune response against self-peptides. As with most vaccines, however, immunogens require supplementation with adjuvants to elicit an optimum immune response. In the present study, we prepared a double-chain mini-protein with each chain containing three linear repeats of the self-peptide gonadotropin-releasing hormone (GnRH3), the hinge region of human IgG1 (hinge), and a T-helper epitope from the measles virus protein (MVP). The GnRH3-hinge-MVP mini-protein was conjugated to purified recombinant heat shock protein 65 (Hsp 65) of Mycobacterium bovis and used to immunize rats primed with subcutaneous injections of Bacillus Calmette-Guerin (BCG) in the absence of adjuvants. The GnRH3-hinge-MVP-Hsp 65 stimulated the production of specific anti-GnRH antibodies in the absence of adjuvants and the antibody titer was comparable to that produced in rats immunized with the dimeric mini-protein in the presence of Freund's adjuvant. Moreover, immunization with the adjuvant-free GnRH3-hinge-MVP-Hsp 65 induced degeneration of the reproductive organs in both male and female rats unlike those immunized in the absence of Hsp 65 or in control animals inoculated with the vehicle only. Histological examination of the affected organs showed atrophy of the seminiferous tubules with diminished spermatogenesis in the testes of male rats. In female rats, the uteri were much smaller in size and the ovaries exhibited reduced follicular development. These findings demonstrated that GnRH3-hinge-MVP-Hsp 65 mounted a strong immune response in the absence of conventional adjuvants, and could prove useful in control of fertility and the treatment of conditions/diseases where GnRH ablation is required.
Collapse
Affiliation(s)
- Xu Jinshu
- The Minigene Pharmacy Laboratory, Biopharmaceutical College, China Pharmaceutical University, Tong Jia Xiang 24, Nanjing 210009 Jiangsu, PR China
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Turkstra JA, Schaaper WMM, Oonk HB, Meloen RH. GnRH tandem peptides for inducing an immunogenic response to GnRH-I without cross-reactivity to other GnRH isoforms. Vaccine 2005; 23:4915-20. [PMID: 16006018 DOI: 10.1016/j.vaccine.2005.05.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2004] [Revised: 04/14/2005] [Accepted: 05/20/2005] [Indexed: 10/25/2022]
Abstract
Gonadotropin releasing hormone (GnRH) occurs in various isoforms in mammals, i.e. GnRH-I (mammalian GnRH), GnRH-II (chicken GnRH-II), GnRH-III (salmon GnRH) and two forms of lamprey GnRH. The function of the latter four molecules have only been partially investigated. Also not much is known about the physiological effects of GnRH-I immunization on the function of these GnRH isoforms. In order to avoid possible harmful side-effects due to undesired neutralization of GnRH isoforms, GnRH-I specificity of antibodies raised against a panel of alternative GnRH antigens was determined. The results show that GnRH antigens can be designed which generate antibodies that specifically bind GnRH-I, without cross-reacting with other GnRH isoforms.
Collapse
Affiliation(s)
- J A Turkstra
- Pepscan Systems, Edelhertweg 15, 8219 PH, Lelystad, The Netherlands.
| | | | | | | |
Collapse
|
11
|
Nagy A, Schally AV. Targeting of cytotoxic luteinizing hormone-releasing hormone analogs to breast, ovarian, endometrial, and prostate cancers. Biol Reprod 2005; 73:851-9. [PMID: 16033997 DOI: 10.1095/biolreprod.105.043489] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Targeted chemotherapy is a modern approach aimed at increasing the efficacy of systemic chemotherapy and reducing its side effects. The peptide receptors expressed primarily on cancerous cells can serve as targets for a selective destruction of malignant tumors. Binding sites for LHRH (now known in genome and microarray databases as GNRH1), were found on 52% of human breast cancers, about 80% of human ovarian and endometrial cancers, and 86% of human prostatic carcinoma specimens. Because LHRH receptors are not expressed on most normal tissues, they represent a specific target for cancer chemotherapy with antineoplastic agents linked to an LHRH vector molecule. To test the efficacy of targeted chemotherapy based on LHRH analogs, we recently developed a cytotoxic analog of LHRH, designated AN-152, which consists of [D-Lys6]LHRH covalently linked to one of the most widely used chemotherapeutic agents, doxorubicin (DOX). In addition, we designed and synthesized a highly active derivative of DOX, 2-pyrrolino-DOX (AN-201), which is 500-1000 times more potent than DOX in vitro. AN-201 is active against tumors resistant to DOX, and noncardiotoxic. As in the case of DOX, AN-201 was coupled to carrier peptide [D-Lys6]LHRH to form a superactive targeted cytotoxic LHRH analog, AN-207. Both AN-152 and AN-207 can effectively inhibit the growth of LHRH receptor-positive human breast, ovarian, endometrial, and prostate cancers xenografted into nude mice. DOX-containing cytotoxic LHRH analog AN-152 is scheduled for clinical phase I/IIa trials in patients with advanced ovarian and breast cancers in 2005.
Collapse
Affiliation(s)
- Attila Nagy
- Section of Experimental Medicine, Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana 70112, USA
| | | |
Collapse
|
12
|
Jinshu X, Jingjing L, Duan P, Zheng Z, Ding M, Jie W, Rongyue C, Zhuoyi H. The immunogenicity of recombinant and dimeric gonadotrophin-releasing hormone vaccines incorporating a T-helper epitope and GnRH or repeated GnRH units. J Immunol Methods 2004; 289:111-22. [PMID: 15251417 DOI: 10.1016/j.jim.2004.04.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2003] [Revised: 10/30/2003] [Accepted: 04/07/2004] [Indexed: 10/26/2022]
Abstract
In this study, we designed two linear peptides, GnRH-hinge-MVP, which consists of human gonadotrophin-releasing hormone (GnRH), hinge fragment 225-232/225'-232' of human IgG1 and a T helper peptide from measles virus protein (MVP), and GnRH3-hinge-MVP, which contains three copies of GnRH (so termed GnRH3). The DNA constructs encoding for the two peptides were fused to the C-terminal encoding sequence of asparaginase, encompassing residues 199-326, through an acid-labile aspartyl-prolyl linker. The chimeric genes were expressed at high levels in Escherichia coli. The fusion proteins were purified to approximate homogeneity by means of washing the inclusion bodies and by ethanol precipitation. The GnRH-hinge-MVP or the GnRH3-hinge-MVP was released from the fusion proteins by cleavage with hydrochloric acid and further oxidized into double-chain miniproteins after purification. Both dimeric constructs proved to be efficient immunogens. It was shown that rats immunized with the immunogens generated antibodies specific for GnRH. The dimeric GnRH3-hinge-MVP containing three copies of GnRH in each chain induced a higher titre of anti-GnRH antibodies than the GnRH-hinge-MVP, containing a single copy of GnRH in each chain. These results demonstrate that combining multicopies or single copies of peptide with hinge fragment of human IgG and T helper peptide from measles virus protein can induce anti-peptide immune responses. Our data also suggest that these methods of preparation and dimerization of the recombinant polypeptides may provide a useful strategy for other polypeptide vaccine developments.
Collapse
Affiliation(s)
- Xu Jinshu
- Minigene Pharmacy Laboratory, Biopharmaceutical College, China Pharmaceutical University, Nanjing, PR China
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Qi L, Nett TM, Allen MC, Sha X, Harrison GS, Frederick BA, Crawford ED, Glode LM. Binding and cytotoxicity of conjugated and recombinant fusion proteins targeted to the gonadotropin-releasing hormone receptor. Cancer Res 2004; 64:2090-5. [PMID: 15026348 DOI: 10.1158/0008-5472.can-3192-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pokeweed antiviral protein (PAP) is a plant-derived, highly potent ribosome inactivating protein that causes inhibition of protein translation and rapid cell death. We and others have delivered this protein to various cell types, including cancer cells, using hormones to specifically target cells bearing the hormone receptor. Here, we compare binding and cytotoxicity of GnRH-PAP hormonotoxins prepared either by protein conjugation (GnRH-PAP conjugate) or through recombinant DNA technology (GnRH-PAP fusion). Although GnRH-PAP conjugate protein bound specifically to and caused cell death in cells bearing the gonadotropin-releasing hormone (GnRH) receptor, we could not detect binding or cytotoxicity using two different versions of the fusion protein in receptor-positive cells. We conclude that generation of an active GnRH-PAP fusion protein may not be feasible either because both ends of the GnRH molecule are required for receptor binding, but only the NH(2) terminus is free in the fusion protein and/or that more potent analogues of GnRH (inclusion of which is not feasible in the fusion protein) are needed for efficient targeting. In contrast, the GnRH-PAP conjugate shows promise as a novel anticancer agent, capable of targeting cancer cells expressing the GnRH receptor such as prostate, breast, ovarian, endometrial, and pancreatic cells. It may also be useful as a therapeutic agent to eliminate pituitary gonadotrophs, eliminating the need for chronic GnRH analogue administration to treat hormone-sensitive diseases.
Collapse
Affiliation(s)
- Lin Qi
- Department of Medicine, Division of Medical Oncology, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Denver, CO 80262, USA
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Parkinson RJ, Simms MS, Broome P, Humphreys JE, Bishop MC. A Vaccination Strategy for the Long-Term Suppression of Androgens in Advanced Prostate Cancer. Eur Urol 2004; 45:171-4; discussion 174-5. [PMID: 14734002 DOI: 10.1016/j.eururo.2003.10.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES We have previously reported the ability of D17DT (formerly GnRH-DT) vaccination to produce castrate levels of androgens in men with advanced prostate cancer. This study examines the efficacy and tolerability of 3 and 15 micrograms of D17DT in 12 patients with advanced prostate cancer to establish a dose-response relationship. METHODS 12 patients received either 3 or 15 micrograms of D17DT as 3 deep intramuscular injections over 6 weeks. Outcome was assessed in terms of physical and biochemical evaluations of clinical progression and antibody titres. RESULTS Significant titres of anti-GnRH antibodies were detected in 2 out of 6 subjects who received 15 micrograms of D17DT; suppression of testosterone to castrate levels accompanied by a significant and prolonged reduction in PSA was also demonstrated. No responses were seen following treatment with 3 micrograms of D17DT. CONCLUSION The induction of anti-GnRH antibodies through vaccination with 15 micrograms D17DT can produce and sustain castrate levels of testosterone in men with advanced prostate cancer.
Collapse
Affiliation(s)
- R J Parkinson
- Department of Urology, Nottingham City Hospital, Hucknall Road, NG5 1PB Nottingham, UK.
| | | | | | | | | |
Collapse
|
15
|
Fromme B, Eftekhari P, Van Regenmortel M, Hoebeke J, Katz A, Millar R. A novel retro-inverso gonadotropin-releasing hormone (GnRH) immunogen elicits antibodies that neutralize the activity of native GnRH. Endocrinology 2003; 144:3262-9. [PMID: 12810583 DOI: 10.1210/en.2002-221135] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
GnRH vaccines have been successfully used for the inhibition of gonadotropin secretion and gonadal function. As an alternative to native GnRH, retro-inverso (RI) GnRH might be an improved immunogen. The RI peptides are composed of D-amino acids assembled in the reverse order (C to N terminus) in relation to the parent L peptide. These peptides are immunogenic and can produce high titers of antibodies that bind the parent peptide with high affinity and specificity. We show that RI-GnRH peptides conjugated to ovalbumin as well as unconjugated RI-GnRH elicit high titers of anti-GnRH antibodies in rabbits and mice. Antibodies were affinity purified and shown by ELISA to be selective for mammalian GnRH compared with GnRH II and [Gln(8)]GnRH. The binding kinetics of antibody-peptide interactions was determined using biosensor technology (BIACORE). The purified anti-GnRH antibodies inhibited GnRH-stimulated signal transduction in COS-1 cells expressing the human GnRH receptor. Immunization of mice with unconjugated and conjugated RI-GnRH peptide, in the absence of complete Freund's adjuvant, produced antisera that cross-reacted with mammalian GnRH. As RI peptides are resistant to cleavage by proteolytic enzymes, they are potentially orally active. The ability of RI-GnRH peptides to produce antibodies to GnRH without conjugation and without Freund's complete adjuvant constitutes a novel vaccine with improved properties of potential application in animal management and sex hormone-dependent cancers.
Collapse
Affiliation(s)
- B Fromme
- Division of Medical Biochemistry, University of Cape Town Faculty of Health Sciences, 7925 Observatory, South Africa
| | | | | | | | | | | |
Collapse
|
16
|
Simms MS, Scholfield DP, Jacobs E, Michaeli D, Broome P, Humphreys JE, Bishop MC. Anti-GnRH antibodies can induce castrate levels of testosterone in patients with advanced prostate cancer. Br J Cancer 2000; 83:443-6. [PMID: 10945488 PMCID: PMC2374644 DOI: 10.1054/bjoc.2000.1315] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
D17DT consists of the GnRH decapeptide linked to diphtheria toxoid. The aim of this pilot study was to assess the tolerance of D17DT and the production of anti-GnRH antibodies from two doses, 30 and 100 microg, in patients with locally advanced prostate cancer. Twelve patients with histologically proven prostate cancer in whom hormonal therapy was indicated were recruited. Patients received either 30 or 100 microg given intramuscularly on three separate occasions over six weeks. Patients were followed up and blood was taken for estimation of serum testosterone, PSA and anti-GnRH antibody titre. Overall the drug was well tolerated. In 5 patients a significant reduction in serum testosterone and PSA was seen. Castrate levels of testosterone were achieved in 4 and maintained for up to 9 months. Patients with the highest antibody titre had the best response in terms of testosterone suppression. This study shows that it is possible to immunize a patient with prostate cancer against GnRH to induce castrate levels of testosterone. This state appears to be reversible. This novel form of immunotherapy may have advantages over conventional forms of hormonal therapy and further studies are warranted in order to try and increase the proportion of responders.
Collapse
Affiliation(s)
- M S Simms
- Department of Urology, City Hospital, Nottingham, UK
| | | | | | | | | | | | | |
Collapse
|