REPURPOSED ANTIBIOTICS FOR NON-NUCLEAR GENOTOXIC CHEMOTHERAPY AND PHARMACEUTICAL COMPOSITION FOR ANTI-CANCER CONTAINING THE SAME
20220000887 · 2022-01-06
Assignee
Inventors
Cpc classification
C07F9/65583
CHEMISTRY; METALLURGY
A61P35/00
HUMAN NECESSITIES
International classification
Abstract
The present invention relates to a repurposed antibiotic compound for the treatment of cancer with minimal nuclear gene damage and an anticancer pharmaceutical composition comprising same. Since the repurposed antibiotic compound has a therapeutic effect in a manner that targets only the mitochondria of cancer cells, the modified antibiotic compound does not cause gene degeneration unlike conventional chemotherapy which damages nuclear DNAs to kill cancer cells, thereby preventing the recurrence of cancer. In addition, a mitochondria targeted therapy using the compound according to the present invention can effectively treat malignant tumors that are difficult to treat due to acquiring drug resistance by general anticancer treatment.
Claims
1. A modified antibiotic anticancer compound represented by Formula 1: ##STR00007## wherein D is a fluoroquinolone antibiotic; X is connected to D and is selected from O, S and NR (wherein R is selected from hydrogen, C.sub.1-C.sub.30 alkyl groups, C.sub.6-C.sub.30 aryl groups, and C.sub.2-C.sub.30 heteroaryl groups); L is selected from C.sub.1-C.sub.30 alkyl groups, C.sub.2-C.sub.30 alkenyl groups, and polyalkylene glycol groups; Q is selected from N, P, As, and Sb; R.sub.1 to R.sub.3 are the same as or different from each other and are each independently selected from C.sub.1-C.sub.30 alkyl groups, C.sub.2-C.sub.30 alkenyl groups, C.sub.6-C.sub.30 aryl groups, and C.sub.2-C.sub.30 heteroaryl groups; and A.sup.− is an anion selected from halogen, hydroxyl, carboxylate, sulfate, sulfamate, sulfonate, phosphate, phosphonate, boronate, and (poly)ethyleneoxy anions.
2. The modified antibiotic anticancer compound according to claim 1, wherein D in Formula 1 is a fluoroquinolone antibiotic selected from flumequine, oxolinic acid, rosoxacin, cinoxacin, nalidixic acid, piromidic acid, pipemidic acid, ciprofloxacin, fleroxacin, lomefloxacin, nadifloxacin, norfloxacin, ofloxacin, pefloxacin, rufloxacin, enoxacin, balofloxacin, grepafloxacin, levofloxacin, pazufloxacin sparfloxacin, temafloxacin, tosufloxacin, clinafloxacin, gatifloxacin, moxifloxacin, sitafloxacin, prulifloxacin, besifloxacin, gemifloxacin, trovafloxacin, delafloxacin, danofloxacin, difloxacin, enrofloxacin, ibafloxacin, marbofloxacin, orbifloxacin, and sarafloxacin.
3. The modified antibiotic anticancer compound according to claim 1, wherein the compound of Formula 1 is selected from: ##STR00008## wherein A.sup.− is as defined in claim 1 and n is an integer from 1 to 30; and ##STR00009## wherein A.sup.− and n are as defined above.
4. The modified antibiotic anticancer compound according to claim 1, wherein the compound of Formula 1 selectively targets mitochondria in cancer cells.
5. The modified antibiotic anticancer compound according to claim 1, wherein the compound of Formula 1 inhibits the mitochondrial electron transport chain (ETC) and mitochondrial DNA synthesis in cancer cells.
6. A pharmaceutical composition for preventing and treating cancer diseases, comprising the modified antibiotic anticancer compound according to claim 1 or a salt thereof as an active ingredient.
7. The pharmaceutical composition according to claim 6, wherein the pharmaceutical composition selectively targets mitochondria in cancer cells.
8. The pharmaceutical composition according to claim 6, wherein the pharmaceutical composition inhibits the mitochondrial electron transport chain (ETC) and mitochondrial DNA synthesis in cancer cells.
9. The pharmaceutical composition according to claim 6, wherein the cancer diseases are selected from breast cancer, lung cancer, colon cancer, prostate cancer, and metastatic cancers thereof.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
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[0021]
[0022]
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[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
[0027] The present invention will now be described in more detail.
[0028] The present invention is directed to a modified antibiotic drug for a new concept of anticancer therapy that can inhibit recurrence and metastasis contributed from strong genotoxicity which is a major problem of current anticancer therapies.
[0029] The modified antibiotic anticancer drug compound of the present invention is represented by Formula 1:
##STR00002##
[0030] wherein D is the backbone of a highly stable fluoroquinolone antibiotic selected from flumequine, oxolinic acid, rosoxacin, cinoxacin, nalidixic acid, piromidic acid, pipemidic acid, ciprofloxacin, fleroxacin, lomefloxacin, nadifloxacin, norfloxacin, ofloxacin, pefloxacin, rufloxacin, enoxacin, balofloxacin, grepafloxacin, levofloxacin, pazufloxacin sparfloxacin, temafloxacin, tosufloxacin, clinafloxacin, gatifloxacin, moxifloxacin, sitafloxacin, prulifloxacin, besifloxacin, gemifloxacin, trovafloxacin, delafloxacin, danofloxacin, difloxacin, enrofloxacin, ibafloxacin, marbofloxacin, orbifloxacin, and sarafloxacin; X is connected to the terminal hydroxyl group of the backbone of the fluoroquinolone antibiotic and is selected from O, S and NR (wherein R is selected from hydrogen, C.sub.1-C.sub.30 alkyl groups, C.sub.6-C.sub.30 aryl groups, and C.sub.2-C.sub.30 heteroaryl groups), preferably O or NR; L is a linking group with the targeting group and is selected from C.sub.1-C.sub.30 alkyl groups, C.sub.2-C.sub.30 alkenyl groups, and polyalkylene glycol groups; Q is a Group 15 element selected from N, P, As, and Sb; R.sub.1 to R.sub.3 are the same as or different from each other and are each independently selected from C.sub.1-C.sub.30 alkyl groups, C.sub.2-C.sub.30 alkenyl groups, C.sub.6-C.sub.30 aryl groups, and C.sub.2-C.sub.30 heteroaryl groups; and A.sup.− is an anion selected from halogen, hydroxyl, carboxylate, sulfate, sulfamate, sulfonate, phosphate, phosphonate, boronate, and (poly)ethyleneoxy anions.
[0031] The modified antibiotic anticancer drug compound of the present invention uses the backbone of a highly stable antibiotic as a basic structure and is designed to selectively target mitochondria, achieving enhanced anticancer therapeutic efficacy. In addition, the modified antibiotic anticancer drug compound of the present invention becomes a safe antibiotic drug after the mitochondria-targeting group is hydrolyzed in vivo, causing minimal side effects. When X is an amide group (NR), better in vivo stability of the compound represented by Formula 1 is ensured.
[0032] According to one exemplary embodiment of the present invention, the compound of Formula 1 is selected from, but not limited to:
##STR00003##
[0033] wherein n is an integer from 1 to 30 and A.sup.− is as defined in Formula 1; and
##STR00004##
[0034] wherein n and A.sup.− are as defined above.
[0035] The compound of Formula 1 has the backbone of ciprofloxacin as a fluoroquinolone antibiotic.
[0036] In the Examples section that follows, n is 6 and A.sup.− is a chloride anion. Amide Mt-CFX is a compound obtained by replacing the binding site of Ester Mt-CFX with an amide group for better in vivo stability.
[0037] The present invention is also directed to a pharmaceutical composition for preventing and treating cancer diseases, including the modified antibiotic anticancer compound represented by Formula 1 or a salt thereof as an active ingredient.
[0038] The pharmaceutical composition of the present invention can be used to prevent and treat a wide range of cancer diseases such as primary cancers and their metastatic cancers. Examples of the cancer diseases include, but are not limited to, breast cancer, lung cancer, colon cancer, prostate cancer, and metastatic cancers thereof.
[0039] The pharmaceutical composition of the present invention may be complexed with other known drugs for the prevention or treatment of cancer diseases before administration or may further include one or more other additives selected from carriers, diluents, adjuvants and stabilizers.
[0040] The dosage form of the composition according to the present invention may vary depending on the mode of administration desired. Examples of such dosage forms include, but not limited to, solid, semi-solid, and liquid formulations such as tablets, pills, powders, capsules, gels, ointments, emulsions, and suspensions. The composition of the present invention may be administered in unit dosage forms suitable for single administration of precise dosages. The composition of the present invention may be administered orally or parenterally. For parenteral administration, the composition of the present invention may be administered intravenously, subcutaneously or intramuscularly.
[0041] Depending on the formulation desired, the composition may further include one or more pharmaceutically acceptable carriers, diluents, adjuvants, and stabilizers, which are defined as aqueous-based vehicles commonly used to formulate pharmaceutical compositions for human administration.
[0042] The term “carrier” means a substance that facilitates the incorporation of a compound into cells or tissues. Examples of suitable carriers include, but not limited to, carbohydrate-based compounds, such as lactose, amylose, dextrose, sucrose, sorbitol, mannitol, starch, and cellulose, gum acacia, calcium phosphate, alginate, gelatin, calcium silicate, microcrystalline cellulose, polyvinylpyrrolidone, cellulose, water, syrups, salt solutions, alcohols, gum Arabic, vegetable oils, such as corn oil, cotton seed oil, soybean oil, olive oil, and coconut oil, polyethylene glycol, methyl cellulose, methyl hydroxybenzoate, propyl hydroxybenzoate, talc, magnesium stearate, and mineral oils, which are commonly used to formulate pharmaceutical compositions. The term “diluent” is defined as a substance diluted in water that can dissolve the compound of interest as well as stabilize the biologically active form of the compound. Examples of suitable diluents include distilled water, physiological saline, Ringer's solution, dextrose solution, and Hank's solution. The stabilizers can be selected from the group consisting of proteins, carbohydrates, buffers, and mixtures thereof. The composition of the present invention may optionally further include one or more additives. Examples of such optional additives include, but not limited to, lubricating agents, wetting agents, sweetening agents, flavoring agents, emulsifying agents, suspending agents, and preservatives.
[0043] Such additional additives as carriers, diluents, adjuvants, and stabilizers may be used in amounts effective to acquire pharmaceutically acceptable formulations in view of the solubility, biological activity, and other characteristics of the active ingredient.
MODE FOR CARRYING OUT THE INVENTION
[0044] The present invention will be more specifically explained with reference to the following examples. It will be appreciated by those skilled in the art that these examples are merely illustrative and the scope of the present invention is not limited thereto.
Synthesis Example 1: Synthesis of Ester Mt-CFX
[0045] Ester Mt-CFX was synthesized according to Scheme 1:
##STR00005##
[0046] Compounds 1 and 2 shown in Scheme 1 were synthesized according to methods known in the art.
[0047] (1) Synthesis of Compound 3
[0048] Compound 1 (1 g, 1.975 mmol) and Compound 2 (852 mg, 1.975 mmol) were dissolved in dimethylformamide as a solvent, and then potassium carbonate (819 mg, 5.925 mmol) was slowly added thereto. The mixture was stirred at 50° C. for 12 h. The reaction mixture was evaporated under reduced pressure to remove the solvent. The residue was purified by column chromatography and dissolved in 50 mL of a mixed solution of methanol and distilled water (1/9). NaBF.sub.4 was added to the solution, followed by stirring for 1 h. The reaction mixture was extracted with dichloromethane and distilled water and dissolved in methanol. After addition of Dowex® 1×8 chloride, the resulting mixture was stirred for 6 h. The reaction mixture was filtered and evaporated to remove the solvent.
[0049] (2) Synthesis of Ester Mt-CFX
[0050] Compound 3 was dissolved in 18 mL of a mixed solution of 1,4-dioxane and dichloromethane (4/1), and then 6 mL of 4 N HCl in dioxane was added dropwise thereto at 0° C. The mixture was stirred at room temperature for 12 h. The solvents were removed by evaporation under reduced pressure, affording Ester Mt-CFX.
[0051] .sup.1H NMR (CDCl.sub.3, 500 MHz): δ 8.50 (s, 1H), 7.87-7.70 (m, 15H), 7.66 (d, J=13.1 Hz, 1H), 7.36 (d, J=7.1 Hz, 1H), 4.29-4.23 (m, 2H), 3.69-3.60 (m, 2H), 3.59-3.53 (m, 1H), 3.50-3.42 (m, 4H), 3.30-3.20 (m, 4H), 1.78-1.65 (m, 6H), 1.61-1.53 (m, 2H), 1.39 (d, J=5.9 Hz, 2H), 1.14-1.07 (m, 2H) ppm.
Synthesis Example 2: Synthesis of Amide Mt-CFX
[0052] Amide Mt-CFX was synthesized according to Scheme 2:
##STR00006##
[0053] Compounds 1 and 2 shown in Scheme 2 were synthesized according to methods known in the art.
[0054] (1) Synthesis of Compound 4
[0055] Compound 1 (1 g, 1.975 mmol) was dissolved in 35 mL of a solution of 7 N NH.sub.3 in methanol. The solution was stirred at room temperature for 3 days. Thereafter, the reaction solution was evaporated under reduced pressure to remove the solvent. The residue was purified by column chromatography.
[0056] (2) Synthesis of Compound 5
[0057] Compound 2 (1 g, 2.318 mmol), EDC hydrochloride (667 mg, 3.477 mmol), and 1-hydroxybenzotriazole hydrate (470 mg, 3.477 mmol) were dissolved in dimethylformamide as a solvent. The solution was stirred at room temperature for 30 min. To the reaction solution were added DMAP (425 mg, 3.477 mmol) and Compound 4 (1.025 g, 2.318 mmol). The resulting mixture was stirred for 12 h. The reaction mixture was evaporated under reduced pressure to remove the solvent. The residue was purified by column chromatography and dissolved in 50 mL of a mixed solution of methanol and distilled water (1/9). NaBF.sub.4 was added to the solution, followed by stirring for 1 h. The reaction mixture was extracted with dichloromethane and distilled water and dissolved in methanol. After addition of Dowex® 1×8 chloride, the resulting mixture was stirred for 6 h. The reaction mixture was filtered and evaporated to remove the solvent.
[0058] (3) Synthesis of Amide Mt-CFX
[0059] Compound 5 was dissolved in 18 mL of a mixed solution of 1,4-dioxane and dichloromethane (4/1), and then 6 mL of 4 N HCl in dioxane was added dropwise thereto at 0° C. The mixture was stirred at room temperature for 12 h. The solvents were removed by evaporation under reduced pressure, affording Amide Mt-CFX.
[0060] .sup.1H NMR (MeOD, 500 MHz): δ 8.88 (s, 1H), 7.95-7.74 (m, 17H), 7.69 (d, J=7.2 Hz, 1H) 3.85-3.79 (m, 1H), 3.69-3.64 (m, 4H), 3.54-3.49 (m, 4H), 3.49-3.41 (m, 4H), 1.77-1.70 (m, 2H), 1.70-1.58 (m, 4H), 1.53-1.42 (m, 4H) ppm.
Experimental Example
[0061] 1-1 Animal Cell Culture
[0062] Human metastatic breast cancer cell line MDA-MB-231 (human breast cancer cells), lung cancer cell line A549 (human lung carcinoma cells), human colon cancer cell line SW620 (human colon carcinoma cells), human prostate cancer cell lines DU145 and PC3 (human prostate cancer cells) were cultured in RPMI1640 media and modified Eagle's media (MEM). All media were supplemented with 10% inactivated fetal bovine serum (FBS) and 1% penicillin-streptomycin. All cell lines were cultured at 37° C. and 5% carbon dioxide.
[0063] 1-2. Cell Viability Analysis
[0064] MDA-MB-231, A549, SW620, DU145, and PC3 cells were seeded into 96-well plates and cultured overnight for stabilization. After treatment of the stabilized cells with Ester MT-CFX, Amide MT-CFX, and ciprofloxacin at various concentrations from 0 to 100 μM for 48 h, the amounts of LDH in living cells were measured to determine cell viabilities. Data are shown as the mean±SE of three independent experiments.
[0065] 1-3. Reactive Oxidative Species (ROS) Measurement and Analysis
[0066] The activity of hydrogen peroxide (H.sub.2O.sub.2) produced in cells was evaluated by detection with Amplex® Red reagent (10-acetyl-3,7-dihydroxyphenoxazine; Thermo Fisher scientific). Here, Amplex® Red reagent reacts with H.sub.2O.sub.2 in a stoichiometric ratio of 1:1 in the presence of peroxidase in cells to produce resorufin as a red fluorescent product. The fluorescence of resorufin can be analyzed at excitation and emission wavelengths of 571 nm and 581 nm, respectively. The MDA-MB-231 cell line was seeded into a 96-well plate and treated with 10 μM Ester MT-CFX for 48 h. Thereafter, the amount of hydrogen peroxide was measured. A reaction mixture of 50 μM Amplex® Red reagent and 0.1 U/mL HRP was prepared in Krebs-Ringer phosphate buffer (145 mM NaCl, 5.7 mM sodium phosphate, 4.86 mM KCl, 0.54 mM CaCl.sub.2, 1.22 mM MgSO.sub.4, 5.5 mM glucose, pH 7.35). 100 μL of the reaction mixture was added to each plate well, followed by incubation at 37° C. for 10 min. The brightness of fluorescence was measured at 530-560 nm excitation and 590 nm emission wavelengths using a microplate reader. The MDA-MB-231 cell line was seeded into a confocal dish. Cells were treated with 10 μM Ester MT-CFX for 48 h, followed by incubation with 10 μM CM-H2DCFDA dye for 30 min. CM-H2DCFDA dye is a known marker for reactive oxygen species in cells. The fluorescence of reactive oxygen species produced in cells was imaged by confocal laser scanning microscopy at 492-495 nm excitation and 517-527 nm emission wavelengths.
[0067] 1-4. DNA Oxidation Measurement
[0068] Intracellular DNA oxidation by oxidative stress was analyzed by enzyme-linked immunoassay using a commercially available 8-OHdG ELISA kit. After treatment of the MDA-MB-231 cells with 10 μM Ester MT-CFX and 10 μM CFX for 48 h, the samples were incubated with primary antibodies at 37° C. and secondary antibodies at 37° C. for 1 h. The incubated samples were allowed to stand at room temperature for 15 min for color development. The absorbance values of the resulting solutions were measured at 450 nm using a multiplate reader.
[0069] 1-5. Protein Carbonylation Measurement
[0070] Protein carbonyl groups are known to be important physiological markers of oxidative stress and reactive oxygen species (ROS) are liable to damage intracellular proteins. Protein carbonylation was determined by ELISA. After treatment of MDA-MB-231 cells with 10 μM Ester MT-CFX and 10 μM CFX for 48 h, 10 μL of 1 μg/uL of protein lysate from each sample was denatured with 10 μL of 10% (w/v) SDS and derivatized with 20 μL of 20 mM 2,4-dinitrophenylhydrazine (DNPH) solution prepared in TPA. After incubation at room temperature for 10 min with vortexing every 2 min, the reaction product was neutralized with 20 μL of 2 M Tris-C.sub.1. A 3 μL aliquot of DNP-derivatized sample was diluted with 0.25 mL of adsorption buffer (20 mM NaHCO.sub.3, 150 mM NaCl, 0.25% SDS, pH 8.5), and 100 μL of diluted sample was loaded on to a 96-well plate. The plate was covered with aluminum foil and incubated overnight at 4° C. After incubation, the sample wells were rinsed 5 times with PBST (0.5% Tween 20) and incubated with 200 μL of blocking buffer (1% BSA in adsorption buffer) at 37° C. for 1 h. The sample wells were then incubated with 100 μL of blocking buffer containing goat anti-DNP antibody at room temperature for 1 h. Following incubation, the sample wells were rinsed 5 times with PBST, and incubated with HRP-conjugated rabbit anti-goat IgG antibody at room temperature for 1 h. After washing 5 times with PBST, standard wells were incubated with 100 μL of TMB substrate at room temperature for 2-3 min for color development. The reaction was stopped with 100 μL of 0.5 M H.sub.2SO.sub.4 and the absorbance was measured at 450 nm and 690 nm. After subtraction of background absorbance at 690 nm, the carbonyl content in each sample was determined using a standard curve of oxidized BSA standard.
[0071] 1-6. Lipid Peroxidation Measurement
[0072] Lipid peroxidation is one of the markers for the mechanism of cell damage and can be confirmed by measuring malondialdehyde (MDA), a product of lipid peroxidation. After treatment of the MDA-MB-231 cells with 10 μM Ester MT-CFX and 10 μM CFX for 48 h, 1 mg/mL of each sample was placed in phosphate buffer and incubated in a thermostatic bath at 37° C. for 6 h. 0.5 mL of 0.75% thiobarbituric acid was added to 10 μL of a mixed solution of butylated hydroxytoluene (BHT) quenched with 10% TCA. The mixture was heated at 95° C. for 20 min, cooled, and centrifuged at 780×g for 10 min. The absorbance of the resulting solution was measured at 532 nm using a multiplate reader.
[0073] 1-7. FACS Measurement
[0074] Annexin-V positive apoptotic cells were analyzed by flow cytometry. To this end, the MDA-MB-231 cells were treated with 10 μM Ester MT-CFX for different periods of time (0, 6, 12, and 24 h) and cultured for indicated periods of time. Cells were harvested, washed twice with ice-cold PBS, placed in BD FACS tubes (10.sup.6/mL), and cultured with 10 μg/mL annexin V in PBS containing 10% FBS at room temperature for 30 min. Subsequently, cells were washed with ice-cold PBS and annexin V fluorescence was measured in the FL-1 channel using a FACSCalibur flow cytometer (BD, USA).
[0075] 1-8. Mitochondrial Membrane Potential Measurement
[0076] Mitochondrial membrane potential differences were measured. To this end, the MDA-MB-231 cells were treated with 10 μM Ester MT-CFX for different periods of time (0, 6, 12, and 24 h) and cultured for indicated periods of time. Cells were harvested, washed once with ice-cold PBS, and cultured with 2 M 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethyl-benzimidazolyl carbocyanine chloride (JC-1) at 37° C. for 20 min. The JC-1 stained cells were centrifuged at 1,300 g for 3 min and washed twice with ice-cold PBS. Mitochondrial membrane potentials of JC-1 monomer (green channel) and aggregate (red channel) were measured in different wavelength bands.
[0077] 1-9. Real-Time PCR Analysis
[0078] RNA was extracted from each sample using TRIzol solution. cDNA synthesized from the isolated RNA or intracellular genomic DNA extracted using a genomic DNA isolation kit was used for real-time polymerase chain reaction (PCR).
[0079] The real-time PCR data were normalized by the expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Relative expression levels were expressed as fold changes over the control. The results (mean±SE) were obtained in triplicate and a p value <0.05 was taken to be statistically significant.
[0080] 1-10. Animal Preparation
[0081] Five-week-old immunodeficient male BALB/c-nu-nu mice (Orient bio, Korea) weighing between 18-20 g were used. The animals were bred and housed in a facility maintaining a humidity of 30-40% and a temperature of 22±1° C. on a 12-h light/dark cycle. All animal experiments were approved by the Ethics Committee for Animal Studies at Korea University. Animals were treated in accordance with the protocol approved by the Ethics Committee.
[0082] 1-11. In Vivo Mouse Xenograft Models
[0083] MDA-MB-231 cells (5×10.sup.6 cells) were injected subcutaneously into 6-week-old immunodeficient BALB/c-nu-nu mice weighing between 18-20 g to establish tumor-bearing mouse models. Ciprofloxacin and Ester MT-CFX were injected intravenously into the established tumor-bearing mouse models three times a week. The lengths of the long and short axes of tumors were measured weekly. 12 weeks after the first injection of each compound, the mice were sacrificed and tumor samples were collected for further analysis. The results are shown as the mean±SE of the tumors of 4 mice in each group. Each asterisk (*) indicates a significant difference to the corresponding control.
[0084] 1-12. In Vivo Fluorescence Imaging
[0085] The tumor-targeting ability of Ester MT-CFX and the distribution of Ester MT-CFX in each organ were evaluated. Using an IVIS Lumina Series III Preclinical imaging system (PerkinElmer CO., USA), in vivo spectral fluorescence images were obtained from 1 h to 48 h after injection of 2 μmol/kg of Ester MT-CFX into tumor-bearing mice via the tail vein. Filters used to obtain the in vivo images were measured at an excitation wavelength of 560 nm. The fluorescence images were deconvoluted using the multi-excitation spectral analysis function.
[0086] 1-13. Statistical Analysis
[0087] The mean and standard error (SE) of each group were calculated from three independent experiments done in triplicate. Statistically significant differences between groups were evaluated by one-way analysis of variance (ANOVA) using SAS software (version 9.0, Cary). When the ANOVA showed a significant difference, comparisons of group means were performed using Student's t-tests. A p value <0.05 was taken to be statistically significant.
[0088] Experimental Results
[0089] (1) The commercially available antibiotic ciprofloxacin has little or no apoptotic effect on MDA-MB-231 metastatic breast cancer cells. In contrast, the inventive compound Ester Mt-CFX having a targeting group showed a strong apoptotic effect on MDA-MB-231 cells with an IC.sub.50 of ˜15 μM (
[0090]
[0091] (2) For better in vivo stability, Amide Mt-CFX was synthesized by converting the binding site (ester group) of Ester Mt-CFX to an amide group. The apoptotic effect of Amide Mt-CFX on cancer cells was verified to be similar to that of Ester Mt-CFX (
[0092] The same experimental procedure as described for Ester Mt-CFX (
[0093] (3) The inventive compounds Ester Mt-CFX and Amide Mt-CFX showed apoptotic effects on various cancer cell types, including A549 (lung cancer cells), SW620 (colon cancer cells), DU145 (prostate cancer cells), and PC3 (prostate cancer cells) as well as MDA-MB-231 metastatic breast cancer cells, demonstrating their wide applicability (
[0094] To demonstrate the applicability of the inventive anticancer drugs to various cancer cell types, the same experimental procedure as described for MDA-MB-231 metastatic breast cancer cells (
[0095] (4) The anticancer effect of the inventive modified antibiotic Mt-CFX can be explained by two mechanisms: (i) the accumulation of the compound Mt-CFX in mitochondria to inhibit the electron transport chain (ETC), as a result of which reactive oxygen species are produced (
[0096]
[0097] (5)
[0098]
[0099] After treatment with the inventive Ester Mt-CFX and various anticancer drugs, DNA damage lesions were analyzed by PCR. The results are shown in
[0100] (6) The inventive fluorescent anticancer compound Ester Mt-CFX was selectively accumulated only in cancer tissues, which was confirmed by an in vivo experiment. Treatment with the inventive anticancer compound Ester Mt-CFX caused a significant reduction in cancer volume compared to treatment with the control, demonstrating that the inventive anticancer compound Ester Mt-CFX has a superior therapeutic effect on cancer (
[0101] (7)
[0102] Contrary to the above result, Ester Mt-CFX according to the present invention protects the carboxylic acid moiety with an ester functional group, so zwitterion does not form. Therefore cell influx into the mitochondria of cancer cells occurs efficiently due to the positive effect of phosphonium ion, leading to the result that the two drugs show a difference in the apoptotic effect. This implies that it is preferrable that the position of Mt bound to CFX is determined not to form zwitterion by acid-base reaction between carboxylic acid and piperazine.
INDUSTRIAL APPLICABILITY
[0103] The modified antibiotic anticancer drug of the present invention selectively targets mitochondria in cancer cells to exhibit its therapeutic effect. Thus, the modified antibiotic anticancer drug can prevent cancer recurrence without causing genetic modification, unlike conventional chemotherapy for killing cancer cells by nuclear DNA damage. In addition, the modified antibiotic anticancer drug of the present invention can effectively treat malignant tumors that are difficult to treat by general anticancer therapies due to their acquired drug resistance.