Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K7/00—Peptides having 5 to 20 amino acids in a fully defined sequence; Derivatives thereof
  • C07K7/04—Linear peptides containing only normal peptide links
  • C07K7/06—Linear peptides containing only normal peptide links having 5 to 11 amino acids
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P1/00—Drugs for disorders of the alimentary tract or the digestive system
  • A61P1/02—Stomatological preparations, e.g. drugs for caries, aphtae, periodontitis
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P13/00—Drugs for disorders of the urinary system
  • A61P13/12—Drugs for disorders of the urinary system of the kidneys
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P19/00—Drugs for skeletal disorders
  • A61P19/08—Drugs for skeletal disorders for bone diseases, e.g. rachitism, Paget's disease
  • A61P19/10—Drugs for skeletal disorders for bone diseases, e.g. rachitism, Paget's disease for osteoporosis
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P43/00—Drugs for specific purposes, not provided for in groups A61P1/00-A61P41/00
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P9/00—Drugs for disorders of the cardiovascular system
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
  • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans
  • C07K14/705—Receptors; Cell surface antigens; Cell surface determinants
  • C07K14/72—Receptors; Cell surface antigens; Cell surface determinants for hormones
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K38/00—Medicinal preparations containing peptides

Definitions

• the invention relates to compounds and the use of novel peptide and peptidomimetic antagonists of a G protein coupled receptor, in treatments focused on regulating the fluid filtration in the kidney in case of acute renal failure, end stage renal disease, glomerulonephritis and other nephropathies, on decreasing resorption and bone mineral loss as in osteoporosis and dental diseases and additionally, closure of ductus arteriosus (DA) in premature infants or fetal animals, (b) Description of Prior Art
• Prostaglandins are derived from the oxygenation of arachidonic acid by prostaglandin (PG) synthases.
• Prostaglandins mediate a wide variety of physiological actions, such as vasomothcity, sleep/wake cycle, intestinal secretion, lipolysis, glomerular filtration, mast cell degranulation, neurotransmission, platelet aggregation, leuteolysis, myometrial contraction and labor, inflammation and arthritis, patent ductus arteriosus, cell growth and differentiation.
• Prostanoids mediate their actions through binding to distinct receptors which belong to the super family of rhodopsin- like seven transmembrane helical receptors.
• receptors are coupled to heterot meric G-proteins comprising of ⁇ , ⁇ and ⁇ subunits which, upon activation, elicit alterations in cell calcium, initiate phosphoinositide hydrolysis or promotion or repression of cyclic adenosine monophosphate synthesis.
• PGE 2 pharmacologically-distinct prostanoid receptors for PGE 2 , PGI 2 , PGD 2 , PGF 2 ⁇ and TxA 2
• EP ⁇ EP 2 EP 3 which has several splice variants
• EP 4 Cloned human EP 4 (also known as prostaglandin E2 receptor subtype EP4) is a 488 amino acid glycoprotein, linked to G ⁇ s and involved in stimulation of adenylate cyclase and cAMP synthesis (Abramovitz, M. et al., US patent Nos. 5,759,789 and 5,605,814).
• EP 4 receptor is expressed at a high level in intestine, but at much lower levels in lung, kidney, thymus, uterus and brain (Bastien, Y. et al. 1994 J. Biol. Chem. 269 (16):11873-77).
• EP 4 is expressed in ductus arteriosus (Bhattacharya, M. et al. 1999. Circulation. 100:1751-56).
• EP 4 knock-out mice die after birth due to insufficient closure of ductus arteriosus (Nguyen, M. et al. 1997. Nature. 390: 78-81 ; Segi, E. et al., 1998).
• the mechanism of ductal patency and the role of EP 4 remain elusive.
• PGE 2 is abundantly produced in kidney and is involved in the regulation of renal microcirculation, salt and water transport, renin release (Breyer, M. D. et al. 1998. Kidney Int. 54 (Suppl. 67): S88-94). All EP receptors have been shown to be regionally distributed in the kidney structures (Morath, R. et al. 1999. J. Am. Soc. Nephrol. 10: 1851-60) and are associated with specific functions. All studies on the distribution of EP receptors in kidney showed that EP 4 receptor is uniquely expressed in glomeruli (Breyer, M. D. et al. 1996. Am. J. Physiol.
• IL-1 interleukin-1
• EP4 antagonists would have therapeutic benefits in medical conditions such as osteoporosis, dental diseases and other diseases where bone loss is integral part of the disease process. Lack of selective antagonists to EP4 receptor hindered progress in this area of research; it is therefore one of the objects of the present invention to overcome one or more of these deficiencies in the art.
• prostaglandin E2 receptor subtype EP4 receptor antagonist capable of inhibiting at least one functional consequence of said receptor activity.
• One aim of the present invention is to provide a peptidic or peptidomimetic form of a prostaglandin E2 receptor subtype EP4 antagonist capable of inhibiting at least one of the functional consequences the receptor activation
• Another aim of the invention is to provide a compound which comprises a peptide of the following general formula:
• Y1 is attached to the N-terminus of the peptide and selected from the group consisting of a proton, a sequence of 1-3 amino acids, or a blocking group such as a carbamate group, an acyl group composed of a hydrophobic moiety such as cyclohexyl, phenyl, benzyl, short chain linear and branched alkyl groups of 1-8 carbons of which acetyl and benzoyl are examples;
• R1 is selected from the group consisting of Val, Ala, lie, Gin, Leu, or Arg
• R2 is selected from the group consisting of Ala, lie, Phe, Arg, or Leu
• R3 is selected from the group consisting of Pro, Thr, Ser, Tyr, Leu, or Val
• R4 is selected from the group consisting of Met, Ala, Gly, Ser, Val, or lie
• R5 is selected from the group consisting of Thr, Pro, Tyr, Leu, Gly, or Gin
• R6 is selected from the group consisting of is Val, Cys, lie, Gly, Glu, or Ser
• R7 is selected from the group consisting of is Pro, Val, Cys, Leu, Glu or Asn;
• R8 is selected from the group consisting of is Ser, Leu, Thr, or Ala Z1 is attached to the carboxy-terminus of the peptide and selected from the group consisting of proton, NH 2 , 1-3 amino acids as well as arylalkyl amines such as benzylamine, phenylethylamine, phenylpropylamine, and aliphatic amines possessing short chain linear and branched alkyl groups of 1 to 8 carbons.
• the invention also aims to provide a pharmaceutical composition containing a peptidic or peptidomimetic compound wherein said compound is capable of inhibiting at least one functional consequence of prostaglandin E2 receptor subtype EP4 activity.
• a pharmaceutical composition containing a peptidic or peptidomimetic compound wherein said compound is capable of inhibiting at least one functional consequence of prostaglandin E2 receptor subtype EP4 activity.
• the compound comprises a peptide having a structural formula:
• Y2 is attached to the N-terminus of the peptide and selected from the group consisting of a proton, a sequence of 1-3 amino acids, or a blocking group such as a carbamate group, an acyl group composed of a hydrophobic moiety such as cyclohexyl, phenyl, benzyl, short chain linear and branched alkyl groups of 1-8 carbons of which acetyl and benzoyl are examples; AA1 is selected from the group consisting of no residue, lie, Leu, Phe and related alpha-amino acids possessing hydrophobic side-chains, arylalkyl amines such as benzylamine;
• AA2 is selected from the group consisting of no residue, Leu, lie, Phe and related alpha-amino acids possessing hydrophobic side-chains, arylalkyl amines such as benzylamine;
• AA3 is selected from the group consisting of no residue, Ala, Ser, Thr and other related alpha amino acids possessing side chains containing hydroxyl or H-bond forming groups
• AA4 is selected from the group consisting of Ser, Thr, and related alpha- amino acids possessing side chains containing hydroxyl groups or H-bond forming groups
• AA5 is selected from the group consisting of Ala, Tyr, Phe, and other related alpha amino acids possessing side chains containing benzoyl and phenolic groups as well as arylalkyl amines such as benzylamine
• AA6 is selected from the group consisting of Glu, Gin, Asp, Asn, and related alpha amino acids possessing side chains containing charged or H-bond accepting groups;
• AA7 is selected from the group consisting of no residue, Ala, Cys, Ser, Thr and related alpha-amino acids possessing side chains containing sufhydryl, hydroxyl groups
• AA8 is selected from the group consisting of no residue, lie, Ala, Leu, Phe and other alpha-amino acids possessing hydrophobic side-chains, as well as arylalkyl amines such as benzylamine, phenylethylamine, phenylpropylamine, and aliphatic amines possessing short chain linear and branched alkyl groups of 1 to 8 carbons
• Z2 is attached to the carboxy-terminus of the peptide and selected from the group consisting of proton, NH 2 , 1-3 amino acids as well as arylalkyl amines such as benzylamine, phenylethylamine, phenylpropylamine, and aliphatic amines possessing short chain linear and branched alky
• Another objective is to provide compounds which are capable of modulating the functional consequences of prostaglandin E2 receptor subtype EP4 in assays using cultured cells, tissues and animals.
• It is also an aim of the present invention to provide a composition comprising an antagonist of the prostaglandin E2 receptor subtype EP4 in association with a pharmaceutically acceptable carrier.
• Another aim of the present invention is to provide the use of a pharmaceutical composition containing a prostaglandin E2 receptor subtype EP4 antagonist for improving giomerular filtration and/or urine output of a patient, treating end stage renal disease or acute renal failure, or closing ductus arteriosus (DA) in a premature infant patient.
• a pharmaceutical composition containing a prostaglandin E2 receptor subtype EP4 antagonist for improving giomerular filtration and/or urine output of a patient, treating end stage renal disease or acute renal failure, or closing ductus arteriosus (DA) in a premature infant patient.
• Another aim of the present invention is to provide the use of a pharmaceutical composition containing a prostaglandin E2 receptor subtype EP4 antagonist for the treatment of osteoporosis.
• Fig.1 illustrates the effects of PHG213 on the changes in ocular perfusion pressure in response to PGE 2 .
• Fig.2 illustrates the effects of PHG213 on giomerular filtration rate and urinary volume in normal rats
• Fig.3 illustrates the effects of PHG213 on giomerular filtration rate and urinary volume in diabetic rats
• Fig. 4 illustrates the effects of PHG 213 on ductus arteriosus diameter in fetal sheep measured by Doppler-echocardiography; and Fig. 5 illustrates the effect of PHG213 on osteoclastogenesis
• Prostanoid receptors are G protein coupled receptors whose natural ligands are the cyclooxygenase products of arachidonic acid, a C20:4 unsaturated fatty acid. No known ligands of these receptors are of peptidic in nature.
• Prostaglandin E2 binds many G protein-coupled receptor subtypes of which subtype EP4 is of particular importance in several pathologies. Specific antagonists of EP4 receptor are not available nor is the validation of the functional role of this receptor un mammalian physiology.
• An aim of the present invention is to address such deficiencies in the arts and provide a selective inhibitor of EP4 receptor.
• a novel aspect of the present invention is that the described antagonists of prostaglandin E2 receptor subtype EP4 is peptidic in nature. Also provided herein is a structure of such an antagonist and the possible derivatives which may mimic the functional and structural features of said antagonist in assays involving cells, tissues and animals, as known to people skilled in the art.
• Y1 is attached to the N-terminus of the peptide and selected from the group consisting of a proton, a sequence of 1-3 amino acids, or a blocking group such as a carbamate group, an acyl group composed of a hydrophobic moiety such as cyclohexyl, phenyl, benzyl, short chain linear and branched alkyl groups of 1-8 carbons of which acetyl and benzoyl are examples;
• R1 is selected from the group consisting of Val, Ala, lie, Gin, Leu, or Arg
• R2 is selected from the group consisting of Ala, lie, Phe, Arg, or Leu
• R3 is selected from the group consisting of Pro, Thr, Ser, Tyr, Leu, or Val
• R4 is selected from the group consisting of Met, Ala, Gly, Ser, Val, or lie
• R5 is selected from the group consisting of Thr, Pro, Tyr, Leu, Gly, or Gin
• R6 is selected from the group consisting of is Val, Cys, lie, Gly, Glu, or Ser
• R7 is selected from the group consisting of is Pro, Val, Cys, Leu, Glu or Asn;
• R8 is selected from the group consisting of is Ser, Leu, Thr, or Ala;
• Z1 is attached to the carboxy-terminus of the peptide and selected from the group consisting of proton, NH 2 , 1-3 amino acids as well as arylalkyl amines such as benzylamine, phenylethylamine, phenylpropylamine, and aliphatic amines possessing short chain linear and branched alkyl groups of 1 to 8 carbons.
• composition comprising a peptide having the structure
• Y2 is attached to the N-terminus of the peptide and selected from the group consisting of a proton, a sequence of 1-3 amino acids, or a blocking group such as a carbamate group, an acyl group composed of a hydrophobic moiety such as cyclohexyl, phenyl, benzyl, short chain linear and branched alkyl groups of 1-8 carbons of which acetyl and benzoyl are examples;
• AA1 is selected from the group consisting of no residue, lie, Leu, Phe and related alpha-amino acids possessing hydrophobic side-chains, arylalkyl amines such as benzylamine
• AA2 is selected from the group consisting of no residue, Leu, lie, Phe and related alpha-amino acids possessing hydrophobic side-chains, arylalkyl amines such as benzylamine;
• AA3 is selected from the group consisting of no residue, Ala, Ser, Thr and other related alpha amino acids possessing side chains containing hydroxyl or H-bond forming groups
• AA4 is selected from the group consisting of Ser, Thr, and related alpha- amino acids possessing side chains containing hydroxyl groups or H-bond forming groups
• AA5 is selected from the group consisting of Ala, Tyr, Phe, and other related alpha amino acids possessing side chains containing benzoyl and phenolic groups as well as arylalkyl amines such as benzylamine;
• AA6 is selected from the group consisting of Glu, Gin, Asp, Asn, and related alpha amino acids possessing side chains containing charged or H-bond accepting groups ;
• AA7 is selected from the group consisting of no residue, Ala, Cys, Ser, Thr and related alpha-amino acids possessing side chains containing sufhydryl, hydroxyl groups;
• AA8 is selected from the group consisting of no residue, lie, Ala, Leu, Phe and other alpha-amino acids possessing hydrophobic side-chains, as well as arylalkyl amines such as benzylamine, phenylethylamine, phenylpropylamine, and aliphatic amines possessing short chain linear and branched alkyl groups of 1 to 8 carbons;
• Z2 is attached to the carboxy-terminus of the peptide and selected from the group consisting of proton, NH 2 , 1-3 amino acids as well as arylalkyl amines such as benzylamine, phenylethylamine, phenylpropylamine, and aliphatic amines possessing short chain linear and branched alkyl groups of 1 to 8 carbons.
• amino acid as used herein includes both L and D isomers of the naturally occurring amino acids as well as other nonproteinaceous amino acids used in peptide chemistry to prepare synthetic analogs of peptides.
• naturally-occurring amino acids are glycine, alanine, valine, leucine, isoleucine, serine, threonine, etc.
• non-naturally occurring amino acids are norleucine, norvaline, cyclohexyl alanine, biphenyl alanine, homophenyl alanine, naphthyl alanine, pyridyl alanine, phenyl alanines substituted at the ortho, para and meta positions with alkoxy, halogen or nitro groups etc.
• norleucine norvaline
• cyclohexyl alanine biphenyl alanine
• homophenyl alanine naphthyl alanine
• pyridyl alanine phenyl alanines substituted at the ortho, para and meta positions with alkoxy, halogen or nitro groups etc.
• polar amino acid means any amino acid containing an uncharged residue but is relatively soluble in water.
• hydrophobic amino acid means any amino acid containing an uncharged side chain which is insoluble in water.
• patient denotes any animal, particularly, humans.
• Peptidomimetics It is well known in the art of drug design to identify a substitute compound that mimics the conformation of the peptide, hence reproduces its functional activity, at the same time avoiding the undesirable features of peptides, such as flexibility, protease- sensitivity, oxidizability of constituents, barrier impermeability and size. Such a compound that mimics the peptide is called a "peptidomimetic". The methods of designing and synthesizing peptidomimetics are well known to people skilled in that art.
• conservative amino acid changes may be made to the actual sequence of the peptide, which although they alter the primary sequence of the peptide, do not normally alter its function.
• Conservative amino acid substitutions typically include substitutions within the following groups: glycine, alanine; valine, isoleucine, leucine; aspartic acid, glutamic acid; asparagine, glutamine; serine, threonine; lysine, arginine; phenylalanine, tyrosine.
• Modifications include in vivo, or in vitro chemical derivatization of polypeptides, e.g., acetylation, or carboxylation.
• Further modifications include attachment of polyethylene glycol molecules of various molecular weights (PEGylation) to improve the bioavailabilty, fatty acid modification to improve its barrier penetrability, and modifications by tissue-targeting antibodies or polypeptides, small molecules are also included herein.
• PEGylation polyethylene glycol molecules of various molecular weights
• polypeptides which have been modified using peptide chemistry so as to improve their resistance to proteolytic degradation or to optimize solubility properties or to render them more suitable as a therapeutic agent.
• Analogs of such polypeptides include those containing residues other than naturally occurring L-amino acids, e.g., D-amino acids or non-naturally occurring synthetic amino acids, as known to persons skilled in the art of peptidomimetic chemistry.
• peptides and peptidomimetics used in this invention contained D-amino acids. Furthermore, replacing blocks of amino acids with synthetic scaffolds, as practiced in case of beta turn mimetics, or use beta amino acids in place of natural amino acids are some of the practices in peptidomimetic chemistry.
• Peptide synthesis The synthesis of the peptides and peptidomimetic compounds described in this invention could be achieved by either a complete solid phase synthesis or a mixed technique whereby all or most of the peptide is synthesized by solid phase and the subsequent additions could be made in solution.
• composition comprising an antagonist of a G protein-coupled receptor of prostaglandin E 2 , subtype EP 4 in association with a pharmacologically or physiologically or pharmaceutically acceptable carrier.
• a pharmacologically or physiologically or pharmaceutically acceptable carrier is denoted by the specific application for which the said antagonist is used.
• composition of the invention can be formulated with the composition of the invention using methods known in the art.
• any acceptable carrier such as physiological saline or any other buffer which is compatible with the particular cell or tissue system being investigated. In vitro formulations will thus be readily apparent to the artisan skilled in the art of conducting ligand binding assays using membranes or whole cells, physiological experiments using tissues.
• the activity of the compounds of the present invention could be tested in a variety of assay systems and these are documented in the literature and is known to people versed in that art.
• Cells in which EP4 receptor is expressed naturally such as NIH3T3, or cDNAs are exogenously expressed using recombinant expression vectors, can be used to measure the efficacy and potency of antagonism of the compounds disclosed herein.
• tissues known to express EP4 receptor for example, saphenous vein, intestinal smooth muscle etc., can be used in organ bath assays to measure contraction/dilation or the tissue fragments or the membranes derived from the tissues could be incubated with radiolabelled ligands to measure ligand displacement, GTP binding and hydrolysis, second messenger (e.
• g. cAMP and inositol phosphates synthesis. All these assays involve measuring one or more of the biochemical and physiological consequences of the signal transmission from said receptor, wherein said consequences are selected from the group consisting of GTP binding and hydrolysis by G ⁇ proteins, cyclic adenosine monophosphate synthesis, alterations in cell calcium, smooth muscle contraction or dilation, cell growth and/or differentiation, altered gene expression and smooth muscle contraction or dilation.
• a more physiological way of assaying the activity of a compound listed herein is to introduce the compound in association with a suitable carrier in an animal using a dose range of 1 ⁇ g-1000 mg/Kg body weight and a suitable route of administration (see below).
• the manipulations of the animals, routes of administration and dosing regimens are known to people versed in the art.
• the present invention contains description of the effects of certain compounds tested in rats, pigs and sheep and the methods are given in the examples.
• an antagonist of the invention When administered to a patient in need of a treatment, it may be formulated in any suitable formulation which will depend on number of factors including the particular condition to be treated, the age, the degree of disease or disorder etc.
• the inhibitors of the invention may be administered to a patient in one of the traditional modes (e.g., orally, parenterally, transdermally or transmucosally), in a sustained release formulation using a biodegradable biocompatible polymer, or by on-site delivery using micelles, gels and liposomes, or rectally (e.g., by suppository or enema) or nasally (e.g., by nasal spray).
• formulations may also include those which render the inhibitor capable of crossing the blood brain barrier when administered by any other route.
• the inhibitors of the invention may be formulated so as to target specific types of cells. For example, it is now known in the art to encapsulate or otherwise formulate compounds such that they a directed to specific receptors on cells. Such formulations include antibody-tagging formulations, receptor-ligand binding formulations etc.
• peripheral administration denotes administration of a compound by any route other than direct administration to the brain.
• peripheral administration includes, but is not limited to, oral, nasopharyngeal, intraperitoneal, intramuscular and intravenous administration of any of the compounds of the invention.
• Treatment regimes which are contemplated include a single dose or dosage which is administered hourly, daily, weekly or monthly, or yearly. Dosages may vary from 1 ⁇ g to 1000 mg/kg of body weight of the patient and will be in a form suitable for delivery of the compound. The route of administration may also vary depending upon the disorder to be treated.
• a pharmacological composition containing an EP4 antagonist in situations wherein administraion of such a composition to a patient having a therapeutic need, results in increment in giomerular filtration and urine output. It is also envisaged that said formulation may be given to patients diagnosed with acute renal failure or end stage renal disease or a variety of glomerulopathies or nephropathies.
• a pharmaceutical composition containing an antagonist of EP4 receptor may be administered to a patient or animal diagnosed with bone mineral loss, as seen in conditions of osteoporosis or dental disease or many immune and cancer-related diseases.
• the use of a pharmaceutical preparation containing EP4 antagonist is also included in the present invention where a need to close the patent ductus arteriosus to avoid pulmonary hypertension in a premature infant.
• the dose of an EP4 antagonist may be 1 ⁇ g-1g / Kg of body weight of the patient or animal and administered by a peripheral route.
• Another embodiment of the invention is that the peptide antagonists described in this invention could be used as a tool to validate the novel roles of prostaglandin E2 receptor subtype EP4 in tissues or in whole animals.
• EP 4 receptor is known to be present in glomerulus (Breyer, M.D., 1996; Morath, R., 1999) and ductus arteriosus (Bhattacharya, M. et al., 1999), the precise function of the receptor in these structures and in the physiology of the animal is not known.
• EP 4 receptor As described in the invention by using specific antagonists, inhibition of EP 4 receptor is shown to increase giomerular filtration and urine output in rats, close the ductus arteriosus in fetal sheep and decrease osteoclasogenesis in human spleen cell co-cultures with osteoblasts.
• Another embodiment of the present invention is the use of the antagonist of EP4 receptor in a biochemical assay to validate the function of unknown ligands, physically identify and localize the said receptor in cells and tissues using such techniques as autoradiography, radioligand binding, radioscintigraphy, positron emmision tomography etc. and the specific techniques vary with the experimental subject and are well known to the persons skilled in such an art. Therefore, a kit containing the antagonist of EP4 receptor attached with various labels, such as fluorochromes, radionucleides, immunoaffinity haptens, antibodies and other affinity tags, is also included in the present invention.
• various labels such as fluorochromes, radionucleides, immunoaffinity haptens, antibodies and other affinity tags
• a portion of the cDNA (corresponding to 1 ⁇ g of RNA) was amplified by PCR using 10 ⁇ M each of primers, EP4.1 (5' ATC ATG TCC ACT TCC GGG GTC 3' SEQ ID NO:10) and EP4.2 (5' CTA TTA TAT ACA TTT TTC TGA TAA GTT CAG 3' SEQ ID NO:11 ) and 2 U VentTM polymerase (New England Biolabs, Mississaugua, ON) in ThermopolTM (New England Biolabs, Mississauga, ON) reaction buffer (20 mM Tris-HCI pH 8.8, 10 mM KCI, 10 mM (NH 4 ) 2 SO 4 , 2 mM MgSO 4 , 0.1 % Triton X-100, 0.2 mM dNTPs and 5% DMSO) for 30 cycles (94°C-1 min; 55°C-1 min; 72°C-1.5 min).
• the DNA fragment was purified by agarose gel electrophoresis, phosphorylated by T4 polynucleotide kinase and cloned into Hinc II site of pGEM-3 (Promega, Madison, Wl) by blunt-end ligation using standard molecular biology methods (Maniatis, T. et al. 1989. Molecular cloning: a laboratory manual. Cold Spring Harbor Press. New York). The sequence of the EP 4 cDNA was determined by sequencing.
• EP 4 coding region (Hind lll-Xba I fragment) was cloned into a eukaryotic expression vector, pRC-CMV (Invitrogen, San Diego, CA) to give EP 4 /RC-CMV plasmid.
• HEK293 cells (2x10° cells/well of a 6-well plate) were transfected with EP 4 /RC-CMV using lipofectamineTM (Life technologies, Burlington, ON) according to the instructions supplied by the manufacturer. Briefly, 2 ⁇ g of plasmid was complexed with 4 ⁇ l of lipid in OPTI-MEM medium for 30 min and the DNA-lipid complexes were added to the cells and left for 6 h at 37°C. Later, the medium was replaced with DMEM containing 10% FBS. After two days, the cells were split into DMEM medium and the antibiotic-resistant cells were selected with 1 mg/ml G418 (Life technologies, Burlington, ON). After 10-12 days in selection, G418- resistant colonies were pooled and propagated. EP 4 receptor expression in the pooled population of cells was confirmed by radioligand binding and cAMP synthesis in response to PGE 2 .
• Basal cAMP levels in EP 4 /293 cells were increased compared to the parent HEK293 cells in the presence of isobutyl methylxanthine (IBMX), a phosphodiesterase inhibitor; this is attributed mainly to the increased basal activity of adenylate cylcase due to the over-expression of EP 4 receptor.
• IBMX isobutyl methylxanthine
• the efficacy of the peptide inhibitors was tested on the basal levels of cAMP in these cells.
• EP 4 /293 cells were seeded at 5x10 5 cells/well in 6-well plates and next day, treated with 100 ⁇ M of IBMX for 1 h in the presence or absence of PHG213 (100 ⁇ M). The medium was removed and 0.3 ml of ethanol was added to precipitate the protein and extract cAMP. Protein- free supernatants obtained after centrifugation were lyophilized. The residues were resuspended in binding buffer and the cAMP levels were determined using a commercial kit.
• PHG213 potently decreased the accumulation of cAMP.
• PHG213 is a potent inhibitor of basal activity of EP 4 receptor in these cells.
• the saphenous veins were cleaned of extraneous tissue and cut into 4 mm rings that were placed in individual jacketed organ baths (15 ml; Radnoti Glass, Monrovia, CA) containing Krebs buffer and maintained at 37°C. The solution was bubbled with a mixture of 95%O 2 - 5% CO 2 . In each experiment, 8 rings were used (4 from each saphenous vein) and were equilibrated for 60 min under 2.0 gr passive tension, with frequent washing and tension adjustment. Tension was measured by force-displacement transducers and was recorded on a computerized data acquisition system using the Work Bench software (both from Kent Scientific, Litchfield, CT). Experimental protocol.
• PGE 2 reversed the constriction produced by U46619. Perfusion of PHG213 blocked this dilatory effect of PGE 2 completely. Since it is known that the dilatory effects of PGE 2 are predominantly mediated by EP 4 receptor in choroid of the newborn pig, PHG 213 antagonized the actions of EP 4 receptor and blocked the dilation produced by this receptor.
• EP 4 receptor is localized in glomerulus and possibly, in the collecting duct and we hypothesized that EP 4 antagonist may increase giomerular filtration rate. For this purpose, we have developed and tested
• PHG 213 (SEQ ID NO:1 ) in an in vivo rat model.
• Method Sprague-Dawley adult rats (-250 g) were anesthetized with 50 mg/kg pentobarbitone. Left jugular vein (for infusion) and left carotid artery (for measuring blood pressure) were catheterized and another catheter was placed at the tip of the bladder for collecting urine.
• GFR was calculated as the ratio of urinary inulin concentration to plasma inulin concentration corrected for the volume of the urine and the weight of the animal. The results are shown in Fig. 2.
• the mean blood pressure was not significantly altered by the peptide.
• Urinary flow rate (UV) dramatically increased by 2.3 fold and giomerular filtration rate(GFR) increased by 157%.
• ESRD end-stage renal disease
• drugs that improve GFR will of immense therapeutic value in delaying the progression of the disease.
• EP 4 antagonists could increase giomerular function, we have used the streptozotocin-induced diabetic rat as a model.
• EP 4 receptor both GFR and UV. Mean blood pressure was not significantly altered in these animals, suggesting that EP 4 receptor contributes minimally to blood pressure homeostasis which is a desirable attribute of the drug. These results suggest that in diabetic animals similar to the normal, EP 4 receptor is expressed and regulates giomerular filtration.
• ewes 129-140 days of gestation
• ketamine 30 mg/Kg i.v.
• a caesarian section was performed and the fetus exteriorized.
• the head of the fetus was submerged in a glove filled with saline.
• Femoral and jugular veins were catheterized for systemic blood pressure measurements and drug infusions respectively.
• Ducuts arteriosus (DA) diameter was measured using Doppler echocardiography as described before (Teyssier, G. et al. 1989. J. Cardiovascular Technol. 8: 259-266).
• Echocardiographic measurements were performed with an Acuson 128 XP/10C real time ultrasound imaging system using 7.5 or 5-MHz transducers duplexed with a range-gated Doppler. Doppler signals were filtered by a 100-Hz high- pass filter. The DA was visualized through a left second intercostal parasternal approach. After the drugs were injected, measurements of DA diameter were repeated 3 times at 5 min intervals for the next 20-25 min.
• DA was unchanged for 40 min during the stabilization period.
• PHG213 SEQ ID NO:1
• DA started to constrict and continued for another 15 min and was irreversible.
• PHG213, a peptide antagonist of EP4 receptor blocked the dilatory action of the receptor which is responsible for maintaining the ductus open in the fetus.
• Osteoclasts attach to bone and cause resorption or bone loss. It is therapeutically advantageous to inhibit the increment in the number of osteoclasts (osteoclast differention) in osteoporosis in order to prevent the bone loss.
• PHG213 SEQ ID NO 1
• a coculture system of human fetal spleen cells and human osteoblast cells was used. Method: SaOs-2 cells (immortalized cell line of human osteoblasts) were grown for four days in 24-well plates in alpha-MEM medium containing 10% fetal calf serum , vitamin D3 (10 ⁇ 7 ).
• Confluent SaOs-2 cells were fixed in 1 % paraformaldehyde M) and dexamethasone (10 8 M in phosphate-buffered sline (PBS) for 8 min. The cells were rinsed with PBS 4 times and alpha-MEM containing 10% fetal calf serum and vitamin D3 (10 7 M) was added.
• PBS phosphate-buffered sline
• spleens from human abortuses were cut into small pieces and triturated several times release the cells.
• the spleen cells were cultured in alpha-MEM containing 10% fetal calf serum for 2 days. Spleen cells were trypsinized, rinsed once in PBS and counted using a coulter counter. An aliquot of spleen cells (10 5 cells/well) were placed over the monolayer of fixed SaOs-2 cells for 2 h, after which PHG213 (100 ⁇ M) was added.
• TRAP tartarat-resistant alkaline phosphatase

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