Development of UTX-143, a selective sodium-hydrogen exchange subtype 5 inhibitor, using amiloride as a lead compound.

NHE5, an isoform of the Na+/H+ exchanger (NHE) protein, is an ion-transporting membrane protein that regulates intracellular pH and is highly expressed in colorectal adenocarcinoma. Therefore, we hypothesized that NHE5 inhibitors can be used as anticancer drugs. However, because NHE1 is ubiquitously expressed in all cells, it is extremely important to demonstrate its selective inhibitory activity against NHE5. We used amiloride, an NHE non-selective inhibitor, as a lead compound and created UTX-143, which has NHE5-selective inhibitory activity, using a structure-activity relationship approach. UTX-143 showed selective cytotoxic effects on cancer cells and reduced the migratory and invasive abilities of cancer cells. These results suggest a new concept wherein drugs exhibit cancer-specific cytotoxic effects through selective inhibition of NHE5 and the possibility of UTX-143 as a lead NHE5-selective inhibitor.

Structure-Activity Relationships of UTX-121 Derivatives for the Development of Novel Matrix Metalloproteinase-2/9 Inhibitors.

Celecoxib, a nonsteroidal anti-inflammatory drug, has been reported to have antitumor and antimetastatic activities, and it has potential for application in cancer treatments. The expression of matrix metalloproteinase (MMP)-2/9 is strongly correlated with cancer malignancy, and inhibition of these MMPs is believed to be effective in improving the antitumor and antimetastatic effects of drugs. We have previously revealed that UTX-121, which converted the sulfonamide of celecoxib to methyl ester, has more potent MMP-2/9 inhibitory activity than celecoxib. Based on these findings, we identified compounds with improved MMP inhibitory activity through a structure-activity relationship (SAR) study, using UTX-121 as a lead compound. Among them, compounds 9c and 10c, in which the methyl group of the p-tolyl group was substituted for Cl or F, showed significantly higher antitumor activity than UTX-121, and suppressed the expression of MMP-2/9 and activation of pro MMP-2. Our findings suggest that compounds 9c and 10c may be potent lead compounds for the development of more effective antitumor drugs targeting MMP.

Development of a novel acetyl glucose-modified gefitinib derivative to enhance the radiosensitizing effect.

Various radiosensitizers are being developed to increase the radiation sensitivity of hypoxic cancer cells, which show resistance to radiation. Previously, we demonstrated that an acetyl glucose-modified nitroimidazole derivative showed a high radiosensitizing effect by inhibiting glucose uptake and glycolysis. Based on this finding, we designed and synthesized novel sugar hybrid radiosensitizers, wherein acetyl glucose was introduced into gefitinib. Among them, UTX-114 had higher autophosphorylation and radiosensitizing activity than gefitinib and inhibited glucose uptake. This result supports our hypothesis that an acetyl glucose moiety improves the radiosensitizing effect of the drug, and UTX-114 can be expected to be a leading compound with a radiosensitizing effect.

Photoacoustic in vivo 3D imaging of tumor using a highly tumor-targeting probe under high-threshold conditions.

Three-dimensional (3D) representation of a tumor with respect to its size, shape, location, and boundaries is still a challenge in photoacoustic (PA) imaging using artificial contrast agents as probes. We carried out PA imaging of tumors in mice using 800RS-PMPC, which was obtained by coupling of 800RS, a near-infrared cyanine dye, with PMPC, a highly selective tumor-targeting methacrylate polymer having phosphorylcholine side chains, as a probe. The conjugate 800RS-PMPC forms compact nanoparticles (dDLS = 14.3 nm), retains the biocompatibility of the parent polymer (PMPC) and exhibits unprecedented PA performance. When applied to mice bearing a 6 × 3 × 3 mm3 tumor buried 6 mm beneath the skin, the probe 800RS-PMPC selectively accumulates in the tumor and emits PA signals that are strong enough to be unambiguously distinguished from noise signals of endogenous blood/hemoglobin. The PA image thus obtained under high-threshold conditions allows 3D characterization of the tumor in terms of its size, shape, location, and boundaries.

Therapeutic Effect and Mechanism of Action of Low-molecular-weight Whey Protein Capable of Activating Macrophages in Bovine Mastitis.

BACKGROUND/AIM: Bovine mastitis is caused by the invasion and propagation of pathogenic microorganisms into the udder and mammary gland tissues of cattle. In this study, the therapeutic effect of a low-molecular-weight whey protein (LMW-WP) on bovine mastitis was evaluated. MATERIALS AND METHODS: LMW-WP was orally, intraperitoneally, and vaginally administered to bovine with mastitis. The number of somatic cells in milk was measured 24 h before the administration of LMW-WP. The effect of LMW-WP on cytokine production was measured with a microarray that evaluates the expression of cytokines. RESULTS: In the group that received 1,000 mg intraperitoneally, the somatic cell count was reduced to less than 400,000 at the shipment standard value in three of the four udders, indicating 75% efficacy. The group that received 1,000 mg by vaginal administration showed 67% efficacy. It was confirmed that LMW-WP increased the production of cytokines such as IL-5, IL-6, IL-9, IL-12, MCP-1, and VEGF in mouse macrophage cells, but it did not show any antibacterial activity. CONCLUSION: LMW-WP may be an effective therapeutic agent for bovine mastitis.

A novel celecoxib analog UTX-121 inhibits HT1080 cell invasion by modulating membrane-type 1 matrix metalloproteinase.

We designed and synthesized a celecoxib derivative UTX-121 to enhance its anti-tumor activity. Similar to celecoxib, this compound could also inhibit matrix metalloproteinase (MMP)-9 activity. In addition, UTX-121 suppressed membrane-type 1 MMP (MT1-MMP)-mediated pro-MMP-2 activation by disturbing the cell surface expression of MT1-MMP. UTX-121 also impeded the glycosylation of cell surface proteins, resulting in the suppression of cell attachment to fibronectin. This inhibition by UTX-121 caused the reduction of fibronectin-stimulated focal adhesion kinase activation, Akt activation, and cell migration. Consequently, UTX-121 treatment significantly inhibited fibronectin-induced HT1080 cell invasion into the Matrigel. UTX-121 may be a potent lead compound that can be used to develop a novel anti-tumor drug.

In vivo drug screening method of radiosensitizers using tumor-bearing chick embryo.

In radiotherapy, tumor hypoxia is the main factor responsible for treatment resistance, and the development of radiosensitizers that can overcome this is imperative. However, many drugs that are effective in vitro and in vivo fail in clinical trials, and thus it is necessary to develop an animal model that can be used for the correct evaluation of pharmacokinetics and activity. Developing chicken eggs are commonly used in various research fields such as anticancer drug sensitivity tests and cardiotoxicity tests. We examined whether the radiosensitizing activity of etanidazole, as a hypoxic cell radiosensitizer, could be evaluated using tumor-bearing chick embryo. Following the transplantation of mouse mammary carcinoma EMT6 cells on day 11, a solid tumor was formed on day 15 and an evaluation of the time-course of the tumor revealed that the tumor weight was the highest on day 18. The maximum dose of etanidazole that did not affect tumor growth and fetal survival was 1.0mg and the maximum X-ray dose was 8Gy. Etanidazole was intravenously administered 10min prior to single dose X-ray irradiation. A significant tumor growth inhibitory effect was confirmed with 1.0mg of etanidazole in combination with 8Gy X-ray. In the case of mouse colon cancer colon26 cells, the combination of 3.0mg of etanidazole and 2Gy X-ray showed 2.79 times higher radiosensitizing activity than that observed for the control group. These results demonstrate that it is possible to evaluate the activity of radiosensitizers using tumor-bearing chick embryo.

Enzymatic activation of indolequinone-substituted 5-fluorodeoxyuridine prodrugs in hypoxic cells.

Among the various enzymes, reductases that catalyze one-electron reduction are involved in the selective activation of functional compounds or materials in hypoxia, which is one of the well-known pathophysiological characteristics of solid tumors. Enzymatic one-electron reduction has been recognized as a useful reaction that can be applied in the design of tumor hypoxia-targeting drugs. In this report, we characterized the enzymatic reaction of 5-fluorodeoxyuridine (FdUrd) prodrug bearing an indolequinone unit (IQ-FdUrd), which is a substrate of reductases. IQ-FdUrd was activated to release FdUrd under hypoxic conditions after treatment with cytochrome NADPH P450 reductase. We also confirmed that IQ-FdUrd showed selective cytotoxicity in hypoxic tumor cells.

Radiosensitizing Effect of 5-Aminolevulinic Acid and Protoporphyrin IX on Carbon-ion Beam Irradiation.

BACKGROUND/AIM: Carbon-ion beam is one of the most advanced radiations used for cancer treatment. However, there are tumors that are difficult to suppress with carbon-ion beam alone, thus necessitating development of drugs that can enhance its therapeutic effect. In this regard, the radiosensitizing effect of 5-aminolevulinic acid (ALA) and protoporphyrin IX (PpIX), that is a metabolic intermediate of ALA, on carbon-ion beam was investigated. MATERIALS AND METHODS: Radiosensitizing activity, mitochondrial ROS and DNA double-strand break production of ALA and PpIX were evaluated by irradiation with 1.0 or 1.5-Gy carbon-ion beam to mouse mammary EMT6 tumor cells. RESULTS: Combination of carbon-ion beam and ALA or PpIX showed a significant enhancement of its cytotoxic activity through a significant increase in ROS production in mitochondria. Furthermore, the combined activity of carbon-ion beam and ALA resulted in a significant increase in DNA double-strand breakage. CONCLUSION: ALA selectively accumulates in the mitochondria and PpIX synthesized from ALA reacts with carbon-ion beam to produce ROS that exert antitumor activity.

Concentration-dependent Activation of Inflammatory/Anti-inflammatory Functions of Macrophages by Hydrolyzed Whey Protein.

BACKGROUND/AIM: Whey protein is a mixture of globulins isolated from whey and mainly composed of ß-lactoglobulin, α-lactoalbumin, and lactoferrin. In this study, whey protein was hydrolyzed using various proteases, and the macrophage activation was evaluated. MATERIALS AND METHODS: Hydrolyzed whey protein was prepared using various proteases to evaluate phagocytic activity and cytokine productivity. RESULTS: The results of SDS-PAGE and gel permeation chromatography (GPC) analysis indicated that the molecular weight of whey protein was reduced using various proteases. The hydrolyzed whey protein showed a concentration-dependent induction of macrophage phagocytic activity. In addition, the hydrolyzed whey protein significantly enhanced the production of the inflammatory cytokine, TNF-α. Production of the anti-inflammatory cytokine, IL-10, was not observed at concentrations up to 1 µg, but significant production was confirmed at 100 µg. CONCLUSION: Hydrolyzed whey protein can induce the phagocytic activity of macrophages and activation of the inflammatory/anti-inflammatory functions of the macrophages depends on the concentration of the hydrolyzed whey protein.

Development of a novel Schiff base derivative for enhancing the anticancer potential of 5-aminolevulinic acid-based photodynamic therapy.

5-Aminolevulinic acid (ALA), a precursor of protoporphyrin IX (PpIX), is now widely used for photodynamic diagnosis (ALA-PDD) and photodynamic therapy (ALA-PDT) of various cancers. Recently, we found that treatment of cancer cells with the Schiff base derivative TX-816 along with ALA could significantly increase the efficacy of ALA-PDT. This enhancing effect of TX-816 on ALA-PDT is attributed to 3,5-dichlorosalicylaldehyde (DCSA), a molecule produced by the degradation of TX-816. Similar to TX-816, DCSA significantly enhances the effect of ALA-PDT. Furthermore, DCSA could restore the sensitivity of cancer cells that acquired resistance to ALA-PDT. These results indicate that DCSA, as well as TX-816, is a potent lead compound for the development of an ALA-PDT sensitizer. TX-816 might be a useful compound for designing prodrug-type ALA-PDT enhancers.

Design and Synthesis of Novel Anti-metastatic Hypoxic Cytotoxin TX-2137 Targeting AKT Kinase.

BACKGROUND: The hypoxic microenvironment plays a crucial role in the malignant progression of tumor cells. Moreover, AKT, a serine/threonine kinase, is activated by various extracellular growth factors and is important for cell growth, survival, and motility of leukocytes, fibroblasts, endothelial cells, and tumor cells. Therefore, we aimed to design an anti-metastatic hypoxic cytotoxin which has inhibitory effects on AKT. RESULTS: TX-2137 was designed and synthesized based on the structural similarity of a preexisting AKT1/2 kinase inhibitor and a hypoxic cytotoxin tirapazamine. TX-2137 effectively reduced the expression of phosphorylated AKT and matrix metalloproteinase 9 (MMP9) and showed strong inhibition of the proliferation of B16-F10, HT-1080, and MKN-45 cells. In addition, TX-2137 exhibited hypoxia-selective cytotoxicity towards A549 cells and inhibited liver metastasis of B16-F10 cells in a xenograft chick embryo model in the same way as doxorubicin. CONCLUSION: TX-2137 may be a potent lead compound in the development of a novel anti-metastatic AKT kinase inhibitor.

Polymeric 1 H MRI Probes for Visualizing Tumor In Vivo.

Magnetic resonance imaging (MRI) has become a prominent non- or low-invasive imaging technique, providing high-resolution, three-dimensional images as well as physiological information about tissues. Low-molecular-weight Gd-MRI contrast agents (CAs), such as Gd-DTPA (DTPA: diethylenetriaminepentaacetic acid), are commonly used in the clinical diagnosis, while macromolecular Gd-MRI CAs have several advantages over low-molecular-weight Gd-MRI CAs, which help minimize the dose of CAs and the risk of side effects. Accordingly, we developed chiral dendrimer Gd-MRI CAs, which showed high r1 values. The association constant values (Ka ) of S-isomeric dendrimer CAs to bovine serum albumin (BSA) were higher than those of R-isomeric dendrimer CAs. Besides, based on a totally new concept, we developed 13 C/15 N-enriched multiple-resonance NMR/MRI probes, which realized highly selective observation of the probes and analysis of metabolic reactions of interest. This account summarizes our recent study on developing both chiral dendrimer Gd-MRI CAs, and self-traceable 13 C/15 N-enriched phosphorylcholine polymer probes for early detection of tumors.

5-Aminolevulinic Acid Enhances Ultrasound-mediated Antitumor Activity via Mitochondrial Oxidative Damage in Breast Cancer.

BACKGROUND/AIM: 5-Aminolevulinic acid (5-ALA), a precursor of protoporphyrin IX (PpIX), is now used for photodynamic therapy (PDT) of pre-cancers of the skin and photodynamic diagnosis (PDD) of brain tumors. Sonodynamic therapy (SDT) of cancers with ultrasound has been studied using 5-ALA as a sonosensitizer. In this article, we evaluated the sonosensitizing activity and mode of action of 5-ALA/PpIX by using mouse mammary tumor EMT6 cells. RESULTS: 5-ALA-SDT showed significant antitumor effects toward EMT6 cells in vitro and in vivo. The fluorescence of MitoSOX Red, an indicator specific for mitochondrial superoxide, was significantly increased by 5-ALA-SDT. Moreover, the fluorescence derived from JC-1, an indicator of mitochondrial membrane potential, was also significantly increased by 5-ALA-SDT. These findings suggest that mitochondria are one of the target organelles of 5-ALA-SDT. PpIX enhanced reactive oxygen species (ROS) production from tert-butyl hydroperoxide (tBHP), suggesting that PpIX might stabilize or promote ROS generation from tBHP. CONCLUSION: 5-ALA-SDT showed an antitumor effect in mouse mammary tumor EMT6 cells through oxidation of the mitochondrial membrane via ROS production.

(13)C/(15)N-Enriched l-Dopa as a Triple-Resonance NMR Probe to Monitor Neurotransmitter Dopamine in the Brain and Liver Extracts of Mice.

In an attempt to monitor µm-level trace constituents, we applied here (1)H-{(13)C-(15)N} triple-resonance nuclear magnetic resonance (NMR) to (13)C/(15)N-enriched l-Dopa as the inevitable precursor of the neurotransmitter dopamine in the brain. The perfect selectivity (to render endogenous components silent) and µm-level sensitivity (700 MHz spectrometer equipped with a cryogenic probe) of triple-resonance allowed the unambiguous and quantitative metabolic and pharmacokinetic analyses of administered l-Dopa/dopamine in the brain and liver of mice. The level of dopamine generated in the brain (within the range 7-76 µm, which covers the typical stimulated level of ∼30 µm) could be clearly monitored ex vivo, but was slightly short of the detection limit of a 7 T MR machine for small animals. This work suggests that µm-level trace constituents are potential targets of ex vivo monitoring as long as they contain N atom(s) and their appropriate (13)C/(15)N-enrichment is synthetically accessible.

Pharmacokinetics of Chiral Dendrimer-Triamine-Coordinated Gd-MRI Contrast Agents Evaluated by in Vivo MRI and Estimated by in Vitro QCM.

Recently, we developed novel chiral dendrimer-triamine-coordinated Gd-MRI contrast agents (Gd-MRI CAs), which showed longitudinal relaxivity (r1) values about four times higher than that of clinically used Gd-DTPA (Magnevist(®), Bayer). In our continuing study of pharmacokinetic differences derived from both the chirality and generation of Gd-MRI CAs, we found that the ability of chiral dendrimer Gd-MRI CAs to circulate within the body can be directly evaluated by in vitro MRI (7 T). In this study, the association constants (K(a)) of chiral dendrimer Gd-MRI CAs to bovine serum albumin (BSA), measured and calculated with a quartz crystal microbalance (QCM) in vitro, were found to be an extremely easy means for evaluating the body-circulation ability of chiral dendrimer Gd-MRI CAs. The K(a) values of S-isomeric dendrimer Gd-MRI CAs were generally greater than those of R-isomeric dendrimer Gd-MRI CAs, which is consistent with the results of our previous MRI study in vivo.

Degalactosylated/Desialylated Bovine Colostrum Induces Macrophage Phagocytic Activity Independently of Inflammatory Cytokine Production.

BACKGROUND/AIM: Colostrum contains antibodies, such as immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM), and, therefore, has potent immunomodulating activity. In particular, IgA has an O-linked sugar chain similar to that in the group-specific component (Gc) protein, a precursor of the Gc protein-derived macrophage-activating factor (GcMAF). In the present study, we investigated the macrophage-activating effects of degalactosylated/desialylated bovine colostrum. RESULTS: We detected the positive band in degalactosylated/ desialylated bovine colostrum by western blotting using Helix pomatia agglutinin lectin. We also found that degalactosylated/ desialylated bovine colostrum could significantly enhance the phagocytic activity of mouse peritoneal macrophages in vitro and of intestinal macrophages in vivo. Besides, degalactosylated/desialylated bovine colostrum did not mediate the production of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß). CONCLUSION: Similar to the use of GcMAF, degalactosylated/desialylated bovine colostrum can be used as a potential macrophage activator for various immunotherapies.

Magnetic resonance imaging of tumor with a self-traceable polymer conjugated with an antibody fragment.

A (13)C-enriched phosphorylcholine polymer ((13)C-PMPC) as a self-traceable MR (magnetic resonance) tag was conjugated with a fragment (scFv) of Herceptin, a clinical antibody against antigen Her2. When injected in model mice bearing Her2(+) (gastric) and Her2(-) (pancreatic) tumors, the antibody-tag conjugate (13)C-PMPC-scFv selectively accumulated in the Her2(+) tumor with a rapid build-up/decay (accumulation/clearance) profile and, with the use of the (1)H-(13)C double-resonance (heteronuclear correlation) technique, the Her2(+) gastric tumor was clearly MR imaged.

Magnetic resonance imaging of tumor with a self-traceable phosphorylcholine polymer.

Polymers are concentration-amplified with respect to the monomeric units. We show here that a phosphorylcholine polymer enriched with (13)C/(15)N at the methyl groups is self-traceable by multiple-resonance (heteronuclear-correlation) NMR in tumor-bearing mice inoculated with the mouse rectal cancer cell line (colon 26). Preliminary measurements indicated that the present polymeric nanoprobe was satisfactorily distinguished from lipids and detectable with far sub-micromolar spectroscopic and far sub-millimolar imaging sensitivities. Detailed ex vivo and in vivo studies for the tumor-bearing mice administered the probe with a mean molecular weight of 63,000 and a mean size of 13 nm, revealed the following: (1) this probe accumulates in the tumor highly selectively (besides renal excretion) and efficiently (up to 30% of the injected dose), (2) the tumor can thus be clearly in vivo imaged, the lowest clearly imageable dose of the probe being 100 mg/kg or 2.0 mg/20-g mouse, and (3) the competition between renal excretion and tumor accumulation is size-controlled; that is, the larger (higher molecular-weight) and smaller (lower molecular-weight) portions of the probe undergo tumor accumulation and renal excretion, respectively. The observed size dependence suggests that the efficient tumor-targeting of the present probe is stimulated primarily by the so-called enhanced permeability and retention (EPR) effect, that is, size-allowed invasion of the probe into the tumor tissue via defective vascular wall. Self-traceable polymers thus open an important area of magnetic resonance imaging (MRI) of tumors and may provide a highly potential tool to visualize various delivery/localization processes using synthetic polymers.

Ruthenium complexes with hydrophobic ligands that are key factors for the optical imaging of physiological hypoxia.

The phosphorescence emission of ruthenium complexes was applied to the optical imaging of physiological hypoxia. We prepared three complexes with hydrophobic substituents on the phenanthroline ligand and characterized their emission, which was quenched by molecular oxygen. Among the complexes synthesized in this study, a pyrene chromophore-linked ruthenium complex, Ru-Py, exhibited optimal properties for the imaging of hypoxia; the prolonged lifetime of the triplet excited state of the ruthenium chromophore, which was induced by efficient energy distribution and transfer from the pyrene unit, provided the highest sensitivity towards molecular oxygen. The introduction of hydrophobic pyrene increased the lipophilicity of the complex, leading to enhanced cellular uptake. Consequently, the bright phosphorescence of Ru-Py was seen in the cytoplasm of viable hypoxic cells, whereas the signal from aerobic cells was markedly weaker. Thus, we could clearly discriminate between hypoxic and aerobic cells by monitoring the phosphorescence emission. Furthermore, Ru-Py was applied to optical imaging in live mice. An intramuscular injection of Ru-Py successfully visualized ischemia-based hypoxia, which was constructed by leg banding.