Short-chain analogs of luteinizing hormone-releasing hormone containing cytotoxic moieties (original) (raw)
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Cancer Letters, 1999
Doxorubicin (DOX) and its daunosaminemodified derivative, 2-pyrrolino-DOX, which is 500-1000 times more active than DOX, were incorporated into agonistic and antagonistic analogs of luteinizing hormone-releasing hormone (LH-RH). The conjugation of DOX with LH-RH analogs was performed by using N-(9-fluorenylmethoxycarbonyl)-DOX-14-0-hemiglutarate, a dicarboxylic acid ester derivative of DOX. Coupling this derivative covalently to the E-amino group of the D-Lys side chain of agonist [D-Lys6]LH-RH or antagonistic analog Ac-D-Nal(2)-D-Phe(4C1)-D-Pal(3)-Ser-Tyr-D-Lys-Leu-Arg-Pro-D-Ala-NH2 [where Nal(2) = 3-(2naphthyl)alanine, Pal(3) = 3-(3-pyridyl)alanine, and
Cytotoxic peptides: Naphthoquinonyl derivatives of luteinizing hormone-releasing hormone
Letters in Peptide Science, 1998
In an attempt to produce efficient cytotoxic derivatives of luteinizing hormone-releasing hormone (LH-RH), two novel 1,4-naphthoquinone derivatives of [D-Lys6[-LH-RH were synthesized primarily by solid-phase peptide synthesis, in good yield and high purity. The ability of each analog to produce reactive oxygen species using enzymatic reduction, i.e. NADPH-cytochrome P-450 reductase, was evaluated employing electron spin resonance (ESR) spectroscopy and spin-trapping techniques. The ESR results suggest that the novel cytotoxic analogs are extremely effective in generating oxygen radicals.
Biology of Reproduction, 2005
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-Lys 6 ]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, 2pyrrolino-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-Lys 6 ]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.
The AAPS Journal, 2015
The enzymatic stability, antitumor activity, and gonadotropin stimulatory effects of glycosylated luteinizing hormone-releasing hormone (LHRH) analogs were investigated in this study. Conjugation of carbohydrate units, including lactose (Lac), glucose (GS), and galactose (Gal) to LHRH peptide protected the peptide from proteolytic degradation and increased the peptides' half-lives in human plasma, rat kidney membrane enzymes, and liver homogenate markedly. Among all seven modified analogs, compound 1 (Lac-[Q 1 ][w 6 ]LHRH) and compound 6 (GS 4 -[w 6 ]LHRH) were stable in human plasma during 4 h of experiment. The half-lives of compounds 1 and 6 improved significantly in kidney membrane enzymes (from 3 min for LHRH to 68 and 103 min, respectively). The major cleavage sites for most of the glycosylated compounds were found to be at Trp 3 -Ser 4 and Ser 4 -Tyr 5 in compounds 1-5. Compound 6 was hydrolyzed at Ser 4 -Tyr 5 and the sugar conjugation site. The antiproliferative activity of the glycopeptides was evaluated on LHRH receptor-positive prostate cancer cells. The glycosylated LHRH derivatives had a significant growth inhibitory effect on the LNCaP cells after a 48-h treatment. It was demonstrated that compound 1 significantly increased the release of luteinizing hormone (LH) at 5 and 10 nM concentrations and compound 5 (GS-[Q 1 ]LHRH) stimulated the release of follicle-stimulating hormone (FSH) at 5 nM concentration in dispersed rat pituitary cells (p<0.05). In our studies, compound 1-bearing lactose and D-Trp was the most stable and active and is a promising candidate for future preclinical investigations in terms of in vitro biological activity and metabolic stability.
Novel, Potent Luteinizing Hormone-Releasing Hormone Antagonists with Improved Solubility in Water
Journal of Medicinal Chemistry, 1994
A series of luteinizing hormone-releasing hormone antagonists with new substitutions in position 6 or positions 5 and 6 that included lysine acylated at the e-amino group with different heterocyclic carboxylic acids or amino-substituted heterocyclic carboxylic acids was Synthesized. These novel analogs were synthesized on a solid-phase support via the acylation of lysine residue in otherwise protected resin-bound peptides. All analogs were tested in the rat antiovulatory assay (AOA) and the best of them in in vitro histamine release assay. Introduction of lysine acylated with aminosubstituted heterocyclic carboxylic acids yielded several water-soluble antagonists with good therapeutic ratio (high AOA to low histamine releasing activity). The best antagonist in terms of activity, histamine release, and solubility was nictide: NAc~Nal-~cpa-~Pal-$er-PicLys-~(GANic)-Orn-Leu-ILys-Pro-~AlaNH2 (6ANic = 6-aminonicotinoyl).
Luteinizing hormone-releasing hormone antagonists
Expert Opinion on Therapeutic Patents, 2009
Background: Luteinizing hormone-releasing hormone (LH-RH) plays a central role in the vertebrate reproduction by regulating gonadal activity. Based on its binding to pituitary LH-RH receptors, as well as to LH-RH receptors expressed on cancer cells, LH-RH agonists and antagonists have been developed for different therapeutic applications. Objective/method: Here we give an overview of the most relevant LH-RH antagonists and their therapeutic applications. Recently patented compounds as well as drug formulations and dosage are presented. Conclusion: LH-RH antagonists have found clinical applications in in vitro fertilization, benign prostatic hyperplasia, endometriosis and in the treatment of hormone-dependent tumors. Work in progress is focused on further development of both peptidic and orally active non-peptidic LH-RH antagonists.
Gynecologic Oncology, 1998
In addition to its function as a key hormone in the regulation of the pituitary-gonadal axis, luteinizing hormone-releasing hormone (LHRH) probably also affects various extrapituitary tissues. LHRH binding sites and in vitro antiproliferative effects of LHRH analogues have been reported in human endometrial cancer. The effects of the LHRH agonist leuproreline and LHRH antagonist antide were studied on the cell growth, DNA synthesis, and cell cycle distribution of the human endometrial cancer cell lines HEC-1A and HEC-1B by the sulforhodamine B (SRB) method, [ 3 H]thymidine assay incorporation, and propidium iodide DNA staining, respectively. In the presence of 1.0 -100 M leuproreline the proliferation of HEC-1A cells was significantly reduced as early as 3 days after drug exposure, with a minimum growth value of 69.9 ؎ 3.6% (mean ؎ SE) at the highest concentration tested (100 M). Similar antiproliferative effects were obtained following a 6-day treatment with the LHRH antagonist antide. Also, inhibitory effects on [ 3 H]thymidine incorporation into the DNA of the HEC-1A cell line were noted after a 6-day exposure to both LHRH analogues, in the above-mentioned concentration range. Cell cycle analysis of HEC-1A cells cultured in the presence of 10 M leuproreline and antide showed a slight accumulation of cells in the G 0 /G 1 phase, while the proportions of cells in the S and G 2 /M phases concomitantly decreased. No significant effects on proliferation, DNA synthesis, and cell cycle distribution were observed in HEC-1B cells with either leuproreline or antide (up to 100 and 10 M, respectively) after a 6-day exposure. Both Northern blot analysis and reverse transcription polymerase chain reaction failed to detect expression of mRNA for the LHRH receptor in both HEC-1A and HEC-1B cell lines. In addition, the LHRH analogues did not affect the intracellular free calcium concentration, indicating that the classic signal transduction for LHRH is absent or impaired in HEC-1A cells. The observed direct inhibitory actions on HEC-1A cells support the concept that the two LHRH analogues may exert biological effects via cellular effectors distinct from the "classic" LHRH receptor. Although the mechanism by which these direct actions are produced is still obscure, these results might help to establish the basis for new approaches to the therapy of endometrial cancer.
Journal of Medicinal Chemistry, 1976
<Glu-Leu-Leu-Ser-Tyr-~-Ala-Leu-Arg-Prc-Gly-NH2) and [Valz,Leu3,~-Ala6]-LH-RH completely inhibited the release of LH and FSH induced by 0.3 ng/ml of medium of LH-RH on isolated rat pituitaries, at a dosage of 10 g. [Leuz,Val3,~-Alas]-LH-RH and [Valz,Val3p-Alas]-LH-RH also completely inhibited this response but were one-tenth as active as [ L~u~, L~u~,
Proceedings of the National Academy of Sciences, 2000
Recently, we developed a series of cytotoxic peptide conjugates containing 14-O-glutaryl esters of doxorubicin (DOX) or 2-pyrrolino-DOX (AN-201). Serum carboxylesterase enzymes (CE) can partially hydrolyze these conjugates in the circulation, releasing the cytotoxic radical, before the targeting is complete. CE activity in serum of nude mice is about 10 times higher than in human serum. Thus, we found that the t 1/2 of AN-152, an analog of luteinizing hormone-releasing hormone (LH-RH) containing DOX, at 0.3 mg͞ml is 19.49 ؎ 0.74 min in mouse serum and 126.06 ؎ 3.03 min in human serum in vitro. The addition of a CE inhibitor, diisopropyl fluorophosphate (DFP), to mouse serum in vitro significantly (P < 0.01) prolongs the t 1/2 of AN-152 to 69.63 ؎ 4.44 min. When DFP is used in vivo, 400 nmol͞kg cytotoxic somatostatin analog AN-238 containing AN-201 is well tolerated by mice, whereas all animals die after the same dose without DFP. In contrast, DFP has no effect on the tolerance of AN-201. A better tolerance to AN-238 after DFP treatment is due to the selective uptake of AN-238 by somatostatin receptor-positive tissues. Our results demonstrate that the suppression of the CE activity in nude mice greatly decreases the toxicity of cytotoxic hybrids containing 2-pyrrolino-DOX 14-Ohemiglutarate and brings this animal model closer to the conditions that exist in humans. The use of DFP together with these peptide conjugates in nude mice permits a better understanding of their mechanism of action and improves the clinical predictability of the oncological and toxicological results. targeted chemotherapeutic agents ͉ tolerance ͉ esterase inhibitors ͉ diisopropyl fluorophosphate ‡ On leave from the