CROSS REFERENCE TO RELATED APPLICATION(S)
This application is a Continuation of application Ser. No. 11/837,824, filed Aug. 13, 2007, now U.S. Pat. No. 7,825,271, which is a Continuation application of application Ser. No. 11/743, filed May 1, 2007, now U.S. Pat. No. 7,741,369, which is a Divisional Application of Ser. No. 11/222,172, filed Sep. 8, 2005, now U.S. Pat. No. 7,294,728, which is a Continuation of application Ser. No. 11/040,605, filed Jan. 21, 2005, now U.S. Pat. No. 7,288,569, which claims benefit of Divisional application Ser. No. 10/391,228, filed Mar. 18, 2003, now U.S. Pat. No. 6,887,901, which is a commonly owned Continuation U.S. Ser. No. 09/968, 445, filed Oct. 1, 2001, now U.S. Pat. No. 6,569,075, which is a continuation application of and claims the benefit of commonly owned U.S. Ser. No. 09/309,423, filed May 11, 1999, now U.S. Pat. No. 6,316,648 which is a continuation application of and claims the benefit of commonly owned U.S. Ser. No. 08/712,610, filed on Sep. 13, 1996, now U.S. Pat. No. 6,048,897 which is a continuation-in-part application of and claims the benefit of commonly owned Ser. No. 08/453,125, filed on May 31, 1995, now U.S. Pat. No. 5,648,512 which in turn is a divisional application of commonly owned Ser. No. 08/260,030, filed on Jun. 15, 1994, now U.S. Pat. No. 5,441,951 which in turn is a continuation-in-part application of commonly owned Ser. No. 08/077,300, filed on Jun. 15, 1993, now abandoned. The contents of all of the aforementioned application(s) are hereby incorporated by reference.
The work leading to this invention was supported in part by one or more grants from the U.S. Government. The U.S. Government therefore may have certain rights in the invention.
Lipoxins are a group of biologically active mediators derived from arachidonic acid through the action of lipoxygenase (LO) enzyme systems. (Serhan, C. N. and Samuelsson, B. (1984) Proc. Natl. Acad. Sci. USA 81:5335). Formulation in human cell types is initiated by 5-LO or 15-LO. (Serhan, C. N. (1991) J. Bioenerg. Biomembr. 23:105). Single-cell types generate lipoxins at nanogram levels during human neutrophil-platelet and eosinophil transcellular biosynthesis of eicosanoids. (Serhan, C. N. and Sheppard, K.-A. (1990) J. Clin. Invest. 85:772). LXs are conjugated tetraene-containing eicosanoids that modulate cellular events in several organ systems.
Lipoxin A4 (LXA4) and lipoxin B4 (LXB4) are the two major lipoxins. Each enhances protein kinase C (PKC) activity in nucliei of erythroleukemia cells at 10 nM (Beckman, B. S. et al. (1992) Proc. Soc. Exp. Biol. Med. 201:169). Each elicits prompt vasodilation at nM levels (Busija, D. W. et al. (1989) Am. J. Physiol. 256:H468; Katoh, T. et al. (1992) Am. J. Physiol. 263 (Renal Fluid Electrolyte Physiol. 32):F436). The vasodilatory effects of lipoxins are well-documented. For example, administration of LXA4 in micromolar amounts via inhalation blocks bronchoconstriction in asthmatic patients. (Christie, P. E. et al. (1992) Am. Rev. Respir. Dis. 145:1281).
In the 10−10 M range, LXA4 also stimulates cell proliferation in combination with suboptimal concentrations of granulocyte-macrophage colony stimulating factor (GM-CSF) to induce myeloid bone marrow colony formation (Stenke, L. et al. (1991) Biochem. Biophys. Res. Commun. 180:255). LXA4 also stimulates human mononuclear cell colony formation (Popov, G. K. et al. (1989) Bull. Exp. Biol. Med. 107:93).
LXA4 inhibits chemotaxis of polymorphonuclear leukocytes (Lee, T. H. et al. (1991) Biochem. Biophys. Res. Commun. 180:1416). An equimolar combination of lipoxins has been found to modulate the polymorphonuclear neutrophil-mesangial cell interaction in glomerular inflammation. (Brady, H. R. et al. (1990) Am. J. Physiol. 809). Activation of the polymorphonuclear neutrophils (PMN) includes the release of mediators of structural and functional abnormalities associated with the early stages of glomerular inflammation. (Wilson, C. B. and Dixon, F. J. (1986) In: The Kidney, edited by B. M. Brenner and F. C. Rector. Philadelphia, Pa.: Saunders, p. 800-891).
Lipoxins act as antagonists to leukotrienes (LT), which are mediators of inflammation. LXA4 modulates LTC4-induced obstruction of airways in asthmatic patients. (Christie, P. E. et al. (1992) Am. Rev. Respir. Dis. 145:1281). LXA4 inhibits LTD4- and LTB4-mediated inflammation in animal in vivo models. (Badr, K. F. et al. (1989) Proc. Natl. Acad. Sci. 86:3438; Hedqvist, P. et al. (1989) Acta Physiol. Scand. 137:571). Prior exposure to LXA4 (nM) blocks renal vasoconstrictor actions of LTD4 (Katoh, T. et al. (1992) Am. J. Physiol. 263 (Renal Fluid Electrolyte Physiol. 32) F436). Leukotriene-induced inflammation occurs, for example, in arthritis, asthma, various types of shock, hypertension, renal diseases, allergic reactions, and circulatory diseases including myocardial infarction.
Although lipoxins are potent small molecules that could be administered in vivo to treat a number of diseases and conditions, these molecules are short-lived in vivo. Compounds having the same bio-activities as natural lipoxins, but a longer in vivo half-life would be valuable pharmaceuticals.
SUMMARY OF THE INVENTION
This invention features substantially purified 15-epi-lipoxin compounds. In one embodiment, the 15-epi-lipoxin compound is 15R-5,6,15-trihydroxy-7,9,13-trans-11-cis-eicosatetraenoic acid and in another embodiment, this acid has a 5S,6R, configuration (15-epi-LXA4). In other embodiments, the 15-epi-lipoxin compound is 15R-5,14,15-trihydroxy-6,10,12-trans-8-cis-eicosatetraenoic acid, and this acid has a 5S,14R configuration (15-epi-LXB4). In still other embodiments, the 15-epi-lipoxin compound is 15-hydroxyeicosatetraenoic acid (15-HETE), and this acid has a 15R configuration.
This invention also features lipoxin analogs, which have an active region that is the same or similar to natural lipoxin, but a metabolic transformation region which is more resistant to in vivo catabolism. The instant disclosed lipoxin analogs therefore have the biological activity of natural lipoxins, but a longer metabolic half-life. Certain of the instant disclosed lipoxin analogs may additionally have an increased in vivo potency, higher binding affinity to lipoxin receptors or enhanced bio-activity as compared to natural lipoxins.
Like natural lipoxins, the instant disclosed small molecules are highly potent and biocompatible (i.e. non-toxic). However, unlike natural lipoxins, lipoxins analogs inhibit, resist, or more slowly undergo metabolism and therefore have a longer pharmacological activity. Further, the instant disclosed compounds are more lipophilic than natural lipoxins and therefore are more readily taken up by biological membranes.
In addition, the invention features methods of ameliorating an undesired proliferation of certain cells based on contacting the cells with an effective amount of a substantially purified 15-epi-lipoxin compound. In preferred embodiments, the cells are undergoing cancerous or tumorous growth. Also in preferred embodiments, the cells are selected from the group consisting of: an epithelial cell, a leukocyte, an endothelial cell, and/or a fibroblast. In certain preferred embodiments of the invention, cells are contacted in vivo. In another embodiment, cells are contacted ex vivo.
The invention also features methods for ameliorating a cell proliferative disorder in a subject by administering an effective amount of a substantially purified 15-epi-lipoxin compound.
In another aspect, the invention features pharmaceutical compositions having the substantially purified 15-epi-lipoxin compound of the present invention and a pharmaceutically acceptable carrier. In a preferred embodiment, the 5-epi-lipoxin compound is in an amount effective to prevent an undesired proliferation of cells in a subject. In another embodiment, the pharmaceutical composition includes an effective amount of acetylsalicylic acid (ASA).
The invention further relates to diagnostic and research uses of the lipoxin compounds. Additional features and advantages of the invention will become more apparent from the following detailed description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a graph showing prostaglandin endoperoxide synthase (PGHS) and lipoxygenase (LO) expression in human tumor cell line (A549 cells) alveolar type II epithelial cells. Cells were grown for 24 h at 37° C. in T-75 cm2 flasks in the presence or absence of Interleukin-1β (IL-1β) (1 ng/ml). Extracted total RNA (1 g) was taken for Reverse Transcription (RT) and PCR using specific oligonucleotides for PGHS-1 and -2, 15-, 12- and 5-LO and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Radioactive bands were quantified directly by phosphorimager analysis, normalized to the expression of GAPDH and expressed as fold increase in mRNA levels after exposure to IL-1β. The inset of FIG. 1A shows 15-LO mRNA expression in human lung tissue and peripheral blood monocytes (PBM) with ND meaning 15-LO mRNA expression not detected.
FIG. 1B is a graph showing a RP-HPLC profile of [3H]-labeled mono-hydroxyeicosatetraenoic acids (HETEs) from permeabilized IL-1-treated A549 cells (1.5×106 cells/ml) exposed to [3H]J-arachidonic acid (20 μM) for 20 min at 37° C. Products were extracted and chromatographed using a linear gradient of methanol:H20:acetic acid (65:35:0.01; v/v/v) and methanol:acetic acid (99.9:0.1, v/v) at a flow rate of 1.0 ml/min. Arrows denote co-chromatography of synthetic standards.
FIG. 2A is a graph showing the generation of 15-HETE. A549 cells (6×106 cells/flask) were treated with IL-1β (1 ng/ml) for 24 h, subjected to freeze-thaw (two cycles), exposed for 20 min to either vehicle (0.1% vol/vol ethanol (EtOH)), acetylsalicylic acid (ASA), the cytochrome P450 inhibitor (17-octadecaynoic acid (17-ODYA), 5 M) or the 5-LO inhibitor (Rev-5901 isomer, 5 M) and incubated with arachidonic acid (20 μM) for 20 min at 37° C. In some experiments, cells were heat-denatured (100° C., 60 min) before incubation. Incubations were stopped with addition of methanol (2v), and products were extracted for reversed phase (RP)-high-pressure liquid chromatography (HPLC). Data are means±SEM from four to six separate flasks. *, P<0.05 and **, P<0.01 for treatments versus control are shown.
FIG. 2B is a graph showing the time course of 15-HETE formation from endogenous sources. A549 cells (1.5×106 cells per ml) were grown for 48 h in the absence or presence of IL-1β (1 ng/ml) and incubated (30 min at 37° C.) in 4 ml HBSS with or without A23187 (5 μM). 15-HETE levels were determined by RIA. Results represent the mean±SEM of three different experiments determined by duplicate. *, P<0.05 for treatments versus vehicle are shown.
FIG. 3 is a graph showing the relative chiralities of 15-HETE triggered by ASA. A549 cells (107 cells per flask) were exposed to IL-1β (1 ng/ml) for 24 h, treated with vehicle (0.1% vol/vol ethanol) (□) or ASA (▪) for 20 min and then incubated (30 min, 37° C.) in HBSS containing arachidonic acid (20 μM) and A23187 (5 μM). Products were chromatographed by RP-HPLC (as in FIG. 1B) and the region containing 15-HETE was collected, extracted with chloroform and treated with diazomethane. Chiral analysis was performed with a Bakerbond DNBPG (see Methods for details). Results are representative of two separate experiments showing similar results. The inset of FIG. 3 shows the ratio between A549-derived 15R and 15S-HETE in the absence or presence (filled bars) of ASA.
FIG. 4A is a graph showing a RP-HPLC chromatogram of products from epithelial cell-polymorphonuclear neutrophils (PMN) costimulation. Confluent A549 cells were exposed to IL-1β (1 ng/ml) for 24 h, treated with ASA (20 min) and arachidonic acid (20 μM, 60 s) and each incubated with freshly isolated PMN (A549 cell:PMN cell ratio of 1:8) followed by stimulation with ionophore A23187 (5 μM) in 4 ml of Hank's balanced salt solution (HBSS) for 30 min at 37° C. Products were extracted and taken to RP-HPLC as described in the Methods section of Example 5. The chromatogram was plotted at 300 nm and is representative of n-=6 experiments.
FIG. 4B is a graph showing on-line ultra-violet (UV) spectra of products from the epithelial cell-PMN costimulation described in FIG. 4A. Material eluting beneath peak B was identified as predominantly 15-epi-LXB4.
FIG. 4C is a graph showing on-line UV spectra of products from the epithelial cell-PMN constimulation described in FIG. 4A. Material eluting beneath the illustrated peaks was identified as predominantly 15-epi-LXA4.
FIG. 5A is a graph showing ASA modulating the formation of tetraene-containing lipoxins (lipoxins plus 15-epi-lipoxins) during epithelial cell-PMN costimulation. A549 cells were exposed to IL-ID (1 ng/ml, 24 h) and treated (20 min, 37° C.) with either vehicle (0.1% vol/vol) or ASA, before the addition of arachidonic acid (20 μM, 1 min) and freshly isolated PMN (A549/PMN cell ratio of 1:5). Costimulations were carried out as in FIG. 4A. Results represent the mean±SEM from 3-5 separate donors. The inset of FIG. 5A shows the effect of cell ratio on generation of tetraene-containing lipoxins (lipoxins plus 15-epi-lipoxins) during co-incubations of A549 cells with PMN in the absence (◯) or presence (▪) of ASA.
FIG. 5B is a graph showing ASA modulating the formation of peptidoleukotrienes (LTC4 plus LTD4) during epithelial cell-PMN costimulation according to the conditions outlined in FIG. 5A. The inset of FIG. 5B shows the effect of cell ratio on generation of peptidoleukotrienes (LTC4 plus LTD4) during co-incubations of A549 cells with PMN in the absence (◯) or presence (▪) of ASA.
FIG. 6A is a graph showing the effect of Lipoxin A4 (LXA4), Lipoxin B4 (LXB4), Dexamethasone (DEX) and vehicle alone treatment on A549 cell number over time. A549 cells in 96-well plates were treated with either vehicle (0.15% EtOH) or equimolar concentrations (10−6 M) of LXA4, LXB4 or DEX for up to 96 hours at 37° C. At the indicated intervals, cells were harvested for the 3,(4,5-dimethylthiazoyl-2-yl) 2,5 (diphenyl-tetrazolium bromide) MTT assay. Data are means±SEM of 3-7 experiments performed in quadruplicate. *, P<0.05 and **, P<0.005 for compounds versus vehicle are shown.
FIG. 6B is a graph showing the effect of LXA4, LXB4, and DEX treatment on the percent inhibition of A549 cell proliferation at varying A549 cell concentrations. A549 cells were exposed to LXA4, LXB4 or DEX at the indicated concentrations for 72 hours at 37° C. Results are means±SEM of 5-8 experiments performed in quadruplicate. Results are expressed as the percent inhibition of proliferation relative to vehicle. *, P<0.05, **, P<0.025 and ***, P<0.005 for compounds versus vehicle are shown.
FIG. 7A is a graph showing the effect of LXA4, LXB4 and DEX on A549 cell DNA synthesis, as indicated by 3H-thymidine incorporation, where A549 cells were grown for 72 hours in the presence of LXA4, LXB4 and DEX at varying concentrations ranging between 5 nM to 500 nM. Twenty-four hours before the assay, methyl-[3H]thymidine (2 μCi/ml) was added to each well. Cells were subsequently washed four times with DPBS2+ (4° C.), lysed with 0.25 N Sodium Hydroxide (NaOH), and radioactivity incorporation was monitored. Values represent mean±SEM of 3 different experiments performed in quadruplicate. Results are expressed as the percent of [3H]thymidine incorporation relative to vehicle alone. *, P<0.05 and **, P<0.005 for compounds versus vehicle are shown.
FIG. 7B is a graph showing the effect of LXA4, LXB4 and DEX on the inhibition of A549 cells, where A 549 cells were seeded in 12-well culture plates in the presence of LXA4, LXB4 and DEX (1 μM) and cell counts were obtained at 72 hours by enumerating the trypan-excluding cells. Values represent mean±SEM of 3 different experiments. Results are expressed as the percent inhibition of proliferation relative to buffer. *, P<0.05 for compounds versus vehicle are shown.
FIG. 8 is a diagram showing the proposed biochemical pathway for generating 15-epi-lipoxins. ASA-acetylated PGHS-2 and/or P450 activities contribute to 15R-HETE. Epithelial 15R-HETE undergoes transcellular conversion by Leukocyte 5-LO to a 15-epi-5(6)-epoxytetraene intermediate, which is common to both 15-epi-LXA4 and 15-epi-LXB4.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the following phrases and terms are defined as follows:
A “lipoxin compound” shall mean a natural lipoxin compound (lipoxin A4 or lipoxin B4) and/or a lipoxin analog.
A “lipoxin analog” shall mean a compound which has an “active region” that functions like the active region of a “natural lipoxin”, but which has a “metabolic transformation region” that differs from natural lipoxin. Lipoxin analogs include compounds which are structurally similar to a natural lipoxin, compounds which share the same receptor recognition site, compounds which share the same or similar lipoxin metabolic transformation region as lipoxin, and compounds which are art-recognized as being analogs of lipoxin. Lipoxin analogs include lipoxin analog metabolites. The compounds disclosed herein may contain one or more centers of asymmetry. Where asymmetric carbon atoms are present, more than one stereoisomer is possible, and all possible isomeric forms are intended to be included within the structural representations shown. Optically active (R) and (S) isomers may be resolved using conventional techniques known to the skilled artisan. The present invention is intended to include the possible diastereisomers as well as the racemic and optically resolved isomers.
A preferred lipoxin compound for use in the subject invention is a “15-epi-lipoxin compound”. As used herein, “15-epi-lipoxin compound” is a lipoxin compound in which the absolute configuration at the 15 Carbon is R.
The term “15-epi-lipoxin compound” is intended to encompass precursors. The term “precursor” is intended to refer to chemical intermediates that can be converted in vivo, ex vivo and/or in vitro to form the 15-epi-lipoxin compounds of the invention. The term “precursor” also contemplates prodrugs which are converted in vivo to the 15-epi-lipoxin compounds of the invention (see, e.g., R. B. Silverman, 1992, “The Organic Chemistry of Drug Design and Drug Action”, Academic Press, Chp. 8). Examples of such prodrugs include, but are not limited to esters of hydroxyls and/or carboxyl groups and/or compounds which can be hydrolyzed or otherwise converted in vivo or, ex vivo and/or in vitro into the 15-epi-lipoxin compounds of the present invention.
The terms “corresponding lipoxin” and “natural lipoxin” refer to a naturally-occurring lipoxin or lipoxin metabolite. Where an analog has activity for a lipoxin-specific receptor, the corresponding or natural lipoxin is the normal ligand for that receptor. For example, where an analog is a LXA4 analog having specific activity for a LXA4 specific receptor on differentiated HL-60 cells, the corresponding lipoxin is LXA4. Where an analog has activity as an antagonist to another compound (such as a leukotriene), which is antagonized by a naturally-occurring lipoxin, that natural lipoxin is the corresponding lipoxin.
The term “active region” shall mean the region of a natural lipoxin or lipoxin analog, which is associated with in vivo cellular interactions. The active region may bind the “recognition site” of a cellular lipoxin receptor or a macromolecule or complex of macromolecules, including an enzyme and its cofactor. Preferred lipoxin A4 analogs have an active region comprising C5-C15 of natural lipoxin A4. Preferred lipoxin B4 analogs have an active region comprising C5-C14 of natural lipoxin B4.
The term “recognition site” or receptor is art-recognized and is intended to refer generally to a functional macromolecule or complex of macromolecules with which certain groups of cellular messengers, such as hormones, leukotrienes, and lipoxins, must first interact before the biochemical and physiological responses to those messengers are initiated. As used in this application, a receptor may be isolated, on an intact or permeabilized cell, or in tissue, including an organ. A receptor may be from or in a living subject, or it may be cloned. A receptor may normally exist or it may be induced by a disease state, by an injury, or by artificial means. A compound of this invention may bind reversibly, irreversibly, competitively, noncompetitively, or uncompetitively with respect to the natural substrate of a recognition site.
The term “metabolic transformation region” is intended to refer generally to that portion of a lipoxin, a lipoxin metabolite, or lipoxin analog including a lipoxin analog metabolite, upon which an enzyme or an enzyme and its cofactor attempts to perform one or more metabolic transformations which that enzyme or enzyme and cofactor normally transform on lipoxins. The metabolic transformation region may or may not be susceptible to the transformation. A nonlimiting example of a metabolic transformation region of a lipoxin is a portion of LXA4 that includes the C-13,14 double bond or the C-15 hydroxyl group, or both.
The term “detectable label molecule” is meant to include fluorescent, phosphorescent, and radiolabeled molecules used to trace, track, or identify the compound or receptor recognition site to which the detectable label molecule is bound. The label molecule may be detected by any of the several methods known in the art.
The term “labeled lipoxin analog” is further understood to encompass compounds which are labeled with radioactive isotopes, such as but not limited to tritium (3H), deuterium (2H), carbon (14C), or otherwise labeled (e.g. fluorescently). The compounds of this invention may be labeled or derivatized, for example, for kinetic binding experiments, for further elucidating metabolic pathways and enzymatic mechanisms, or for characterization by methods known in the art of analytical chemistry.
The term “inhibits metabolism” means the blocking or reduction of activity of an enzyme which metabolizes a native lipoxin. The blockage or reduction may occur by covalent bonding, by irreversible binding, by reversible binding which has a practical effect of irreversible binding, or by any other means which prevents the enzyme from operating in its usual manner on another lipoxin analog, including a lipoxin analog metabolite, a lipoxin, or a lipoxin metabolite.
The term “resists metabolism” is meant to include failing to undergo one or more of the metabolic degradative transformations by at least one of the enzymes which metabolize lipoxins. Two nonlimiting examples of LXA4 analog that resists metabolism are 1) a structure which can not be oxidized to the 15-oxo form, and 2) a structure which may be oxidized to the 15-oxo form, but is not susceptible to enzymatic reduction to the 13, 14-dihydro form.
The term “more slowly undergoes metabolism” means having slower reaction kinetics, or requiring more time for the completion of the series of metabolic transformations by one or more of the enzymes which metabolize lipoxin. A nonlimiting example of a LXA4 analog which more slowly undergoes metabolism is a structure which has a higher transition state energy for C-15 dehydrogenation than does LXA4 because the analog is sterically hindered at the C-16.
The term “tissue” is intended to include intact cells, blood, blood preparations such as plasma and serum, bones, joints, muscles, smooth muscles, and organs.
The term “halogen” is meant to include fluorine, chlorine, bromine and iodine, or fluoro, chloro, bromo, and iodo.
The term “pharmaceutically acceptable salt” is intended to include art-recognized pharmaceutically acceptable salts. These non-toxic salts are usually hydrolyzed under physiological conditions, and include organic and inorganic bases. Examples of salts include sodium, potassium, calcium, ammonium, copper, and aluminum as well as primary, secondary, and tertiary amines, basic ion exchange resins, purines, piperazine, and the like. The term is further intended to include esters of lower hydrocarbon groups, such as methyl, ethyl, and propyl.
The term “pharmaceutical composition” comprises one or more lipoxin analogs as active ingredient(s), or a pharmaceutically acceptable salt(s) thereof, and may also contain a pharmaceutically acceptable carrier and optionally other therapeutic ingredients. The compositions include compositions suitable for oral, rectal, ophthalmic, pulmonary, nasal, dermal, topical, parenteral (including subcutaneous, intramuscular and intravenous) or inhalation administration. The most suitable route in any particular case will depend on the nature and severity of the conditions being treated and the nature of the active ingredient(s). The compositions may be presented in unit dosage form and prepared by any of the methods well-known in the art of pharmacy. Dosage regimes may be adjusted for the purpose to improving the therapeutic response. For example, several divided dosages may be administered daily or the dose may be proportionally reduced over time. A person skilled in the art normally may determine the effective dosage amount and the appropriate regime. A lipoxin analog pharmaceutic composition can also refer to a combination comprising lipoxins, lipoxin analogs, and/or lipoxin metabolites, including metabolites of lipoxin analogs. A nonlimiting example of a combination is a mixture comprising a lipoxin analog x which inhibits one enzyme which metabolizes lipoxins and which optionally has specific activity with a lipoxin receptor recognition site, and a second lipoxin analogy which has specific activity with a lipoxin receptor recognition site and which optionally inhibits or resists lipoxin metabolism. This combination results in a longer tissue half-life for at least y since x inhibits one of the enzymes which metabolize lipoxins. Thus, the lipoxin action mediated or antagonized by y is enhanced.
The term “substantially pure or purified” lipoxin compounds are defined as encompassing natural or synthetic compounds of lipoxins having less than about 20% (by dry weight) of other biological macromolecules, and preferably having less than about 5% other biological macromolecules (but water, buffers, and other small molecules, especially moleculess having a molecular weight of less than 5000, can be present. The term “purified” as used herein preferably means at least 80% by dry weight, more preferably in the range of 95-99% by weight, and most preferably at least 99.8% by weight, of biological macromolecules of the same type present (but water, buffers, and other small molecules, especially molecules having a molecular weight of less than 5000, can be present). The term “pure” as used herein preferably has the same numerical limits as “purified” immediately above. “Isolated” and “purified” do not encompass either natural materials in their native state or natural materials that have been separated into components (e.g., in an acrylamide gel) but not obtained either as pure (e.g. lacking contaminating proteins, or chromatography reagents such as denaturing agents and polymers, e.g. acrylamide or agarose) substances or solutions.
The term “subject” is intended to include living organisms susceptible to conditions or diseases caused or contributed to by inflammation, inflammatory responses, vasoconstriction, myeloid suppression and/or undesired cell proliferation. Examples of subjects include humans, dogs, cats, cows, goats, and mice. The term subject is further intended to include transgenic species.
The term “cell proliferative disorder” includes disorders involving the undesired proliferation of a cell. Non-limiting examples of such disorders include tumors, (e.g., brain, lung (small cell and non-small cell), ovary, prostate, breast or colon) or other carcinomas or sarcomas (e.g., leukemia, lymphoma).
The term “ameliorated” in intended to include treatment for, prevention of, limiting of and/or inhibition of undesired cell proliferation and/or a cell proliferative disorder.
The instant invention is based on the surprising finding that substantially pure 15-epi-lipoxin compounds ameliorate undesired cell proliferation in a subject. The 15-epi-lipoxin compounds of the present invention include 15R-5,6,15-trihydroxy-7,9,13-trans-11-cis-eicosatetraenoic acid, in a 5S,6R configuration (15-epi-LXA4). The 15-epi-lipoxin compounds of the present invention also include 15R-5,14,15-trihydroxy-6,10,12-trans-8-cis-eicosatetraenoic acid, in a 5S,14R configuration (15-epi-LXB4). The 15-epi-lipoxins of the present invention further include 15-hydroxyeicosatetraenoic acid, particularly in a 15R configuration.
The instant invention is based on the surprising finding that lipoxins are rapidly metabolized in a unique fashion by certain cells in vivo. Although other LO-derived products (e.g. leukotrienes) are metabolized by ω-oxidation followed by β-oxidation (Huwyler et al., (1992) Eur. J. Biochem. 206, 869-879), the instant invention is based on the unexpected finding that lipoxins are metabolized by a series of oxidation and reduction reactions acting on certain sites of the lipoxin molecule. For example, LXA4 metabolism has been found to occur, at least in part, via oxidation of the C-15 hydroxyl to generate 15-oxo-LXA4, reduction of the C-13,14 double bond to yield 13,14-dihydro-5-oxo-LXA4 and further reduction to yield 13,14-dihydro-LXA4. In LXB4 and its natural isomers the analogous oxidation occurs at the C-5 hydroxyl and reduction occurs at the C-6,7 double bond.
Thus, the instant invention features lipoxin analogs having lipoxin activity, but which are chemically modified to prevent dehydrogenation and therefore subsequent degradation in vivo. In these analogs, the C-1 to C-13 portion of the natural lipoxin may or may not be conserved. Variations of the C-1 to C-13 portion include different cis or trans-geometry as well as substitutions. The disclosed compounds is represented below by a structural genus, which is further divided into subgenuses. Subgenuses included in each of the following two R groups is denoted by a Roman numeral on the left of the page.
The instant lipoxins comprising an “active region” and a “metabolic transformation region” as both terms are defined herein are generally of the following structure:
wherein R1 can be
and R2 can be
In one embodiment, the lipoxin analogs of this invention have the following structural formula I:
wherein X is R1, OR1, or SR1;
wherein R1 is
(ii) alkyl of 1 to 8 carbons atoms, inclusive, which may be straight chain or branched;
(iii) cycloalkyl of 3 to 10 carbon atoms, inclusive;
(iv) aralkyl of 7 to 12 carbon atoms;