Search

Epstein-Barr virus (EBV), a human oncogenic virus, is a B cell-tropic herpesvirus and has the ability to immortalize normal B cells during latent infection. The Epstein-Barr nuclear antigen 1 (EBNA1) protein of EBV is expressed in the most EBV latently infected cells and binds to a specific viral genome region termed "oriP" (origin of plasmid replication) to maintain the stability of the approximately 170 kb double-stranded circular virus genomic DNA (episome) in cells. EBV elimination is thought to inhibit progression of EBV-associated malignancies, and the EBNA1-dependent mechanisms for EBV episome replication and maintenance are considered to be novel molecular targets for anti-EBV therapy. We have explored small-molecule compounds that can inhibit the binding between EBNA1 protein and oriP and found one pyrrole imidazole polyamide named DSE3 which can also inhibit EBV-mediated immortalization of normal B cells. These data suggested that an EBNA1-targeting strategy could be useful to combat EBV-associated malignancies.

Proton pump inhibitors (PPIs) inhibit H + , K + -ATPase, an enzyme which is the final step of gastric acid secretion and is selectively located in the gastric parietal cells. PPIs block the enzyme in a covalent and irreversible binding manner, thus providing better efficacy than previous pharmacological agents such as antacids and histamine H 2 receptor antagonists. Although PPIs have been the first-line therapeutic option for acid related diseases (ARDs), there are several limitations to their efficacy, i.e. short half-life in blood, insufficient acid suppression especially at night, necessity of repeated dosages for full action, and large variation in efficacy among patients due to CYP2C19 polymorphism. To overcome these shortcomings, we performed a high-throughput random screening using in-house chemical libraries and further lead optimization to look for the most relevant clinical candidate compounds. As the results of these researches, we discovered vonoprazan fumarate, a novel gastric acid antisecretory agent which inhibits H + , K + -ATPase in a reversible and K + -competitive manner. Vonoprazan exerted a more potent and longer lasting inhibitory effect than lansoprazole on gastric acid secretion in preclinical studies, presumably by its high accumulation profile in the gastric parietal cells. It also exhibited a rapid onset of action and prolonged inhibition of intragastric acidity in humans and showed remarkable effects on multiple ARDs including erosive esophagitis and Helicobacter pylori eradication. Vonoprazan fumarate was approved in 2014 for clinical use in Japan. Vonoprazan is a new therapeutic option which can potentially improve outcomes compared with conventional PPI-based treatments for ARDs.

The combined use of synthetic disease-modifying anti-rheumatic drugs (sDMARDs) such as methotrexate and biological DMARDs (bDMARDs) has revolutionized treatment of rheumatoid arthritis (RA). Remission is now realistic targets, achieved by a large proportion of RA patients. However, bDMARDs are limited to intravenous or subcutaneous uses and orally available small but strong products have been developed. Oral administration of tofacitinib targeting the Janus kinase (JAK) is significantly effective than placebo in active RA patients with sDMARD-naïve, inadequately responsive to sDMARDs or TNF-inhibitors. The efficacy was rapid and as strong as adalimumab, a TNF-inhibitor. The common adverse events were related to infection, hematologic and hepatic disorders and association of tofacitinib with carcinogenicity and infections remains debated.

Recent advance in treatment of rheumatoid arthritis (RA) has been derived by biological disease-modifying antirheumatic drugs (bDMARDs) targeting cytokines. A Jak inhibitor tofacitinib, the first drug of targeted synthetic DMARD (tsDMARD), a novel category of DMARD, shows similar efficacy profile, but different safety concerns, compared to bDMARDs. It is, therefore, essential to understand the mode of action of tofacitinib in the context of safety and efficacy. We here document the possible mechanism of tofacitinib in patiens with RA, shedding light upon a characteristic adverse event, herpes zoster.

Treatment of rheumatoid arthritis (RA) has dramatically developed with the use of biologics targeting inflammatory cytokines. However, expense and parenteral use can cause issues in the initiation and continuation of the treatment. Therefore a new orally available anti-rheumatic drug has been long-awaited. Recently, small-molecule compounds targeting Janus kinase (JAK) has shown clinical efficacy similar to biologics in clinical trials for active RA. Among the JAK-inhibitors, new drug application for tofacitinib is concurrently under review in western and asian countries and is highly expected to become a new anti-rheumatic drug in the near future. In order to evaluate the mode of action, we utilized peripheral blood and synovium from RA patients. Proliferation and cytokine production of CD4+ T cell was prominently reduced and subsequently inhibited cartilage destruction by the synovium. Our result is in line with the inhibitory effect of tofacitinib on joint destruction in RA patients those who were treated with tofacitinib. Therefore, further clinical efficacy is expected in the in the long-term treatment with tofacitinib.

The widespread emergence of multidrug-resistant Gram-positive pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) is a high threat for human health. In the course of screening for active compounds against the above drug-resistant bacteria from microbial metabolites, we discovered three kinds of novel compounds designated tripropeptins, pargamicin, and amycolamicin. Tripropeptin C (TPPC), major component of tripropeptins, is the most promising compound because it is efficacious against MRSA and VRE both in vitro and in a mouse septicemia model, and shows no cross-resistance to available drugs including vancomycin. Studies of incorporation of radioactive macromolecular precursors and accumulation of UDP-MurNAc-pentapeptide in the cytoplasm in S. aureus Smith revealed that TPPC is a cell wall synthesis inhibitor. Antimicrobial activity of TPPC was weakened by addition of prenylpyrophosphates but not with prenylphosphates, UDP-linked sugars, or the pentapeptide of peptidoglycan. Direct interaction between TPPC and undecaprenyl pyrophosphate (C(55)-PP) was observed by mass spectrometry and thin layer chromatography, and TPPC inhibits C(55)-PP phosphatase, which plays a crucial role in peptidoglycan synthesis at an IC(50) of 0.03-0.1 µM in vitro. From the analysis of accumulation of lipid carrier-related compounds, TPPC caused accumulation of C(55)-PP in situ, leading to the accumulation of a glycine-added lipid intermediate, suggesting a distinct mode of action from that of clinically important drugs such as vancomycin, daptomycin, and bacitracin. TPPC might represent a promising novel class of antibiotic against MRSA and VRE infections.

Objectives: To examine the relationship between insulin resistance (IR) and the reduction of oxidative stress in vivo by the statin atorvastatin., Methods: This study included 40 patients with hypercholesterolemia without a history of diabetes mellitus (21 males, 19 females, mean age 62 +/- 11 years). Homeostasis assessment insulin resistance (HOMA-IR) was used as a marker for insulin resistance. The patients were divided into two groups [IR group (n = 24) and non-IR group (n = 16), using the cut off level of 1.73]. Urinary 8-iso-prostaglandin F2alpha (U-8-iso) excretion was used as an oxidative stress marker. The subjects were treated with atorvastatin (10 mg/day) for 12 weeks., Results: The IR group had significantly higher U-8-iso levels than the non-IR group before atorvastatin administration (211 +/- 112 vs 137 +/- 33 pg/mg Cr, p = 0.01). Low-density lipoprotein cholesterol, triglyceride, and 8-iso levels were significantly reduced in both groups after 12 weeks, U-8-iso levels were significantly higher in the IR group than the non-IR group (178 +/- 61 vs 110 +/- 38 pg/mg Cr, p = 0.003), and HOMA-IR showed no significant change. Multiple regression analysis after 12 weeks showed that HOMA-IR and triglyceride levels were independent variables for U-8-iso levels (standard regression coefficient = 0.60, 0.59, p < 0.0001, p = 0.0002)., Conclusions: Insulin resistance is important in the occurrence of oxidative stress in patients with hypercholesterolemia. Since atorvastatin does not reduce insulin resistance, further therapy to reduce insulin resistance is necessary for early prevention of cardiovascular events during atorvastatin treatment.

Recent progress in molecular biology and cancer biology has revealed that many molecules, which are heavily involved in the un-limited growth, anti-apoptotic effects and invasion of tumors, would be targets of cancer therapy. Part of the drugs which inhibit these molecules have shown clinical response as well as clinical benefits. In this review article, the summary of mechanism based drug screening for cancer as well as recent status of new molecular target drugs for cancer, are described.

Statins, 3-hydroxy-3 methylglutaryl coenzyme A(HMG-CoA) reductase inhibitors, are approved for cholesterol reduction and are commonly used to treat atherosclerosis and coronary disease. Statins may also be potent immunomodulatory agents and be beneficial in the treatment of autoimmune diseases. Statins have already been used to reduce the rejection of human heart transplants by the immune system, and there have been reports of a protective effect of injected statins in models of brain autoimmunity similar to experimental autoimmune encephalomyelitis. In vitro studies in multiple sclerosis(MS) revealed that statins reduced the expression of activation-induced adhesion molecules on T cells, modified Th1/Th2 cytokine balance, reduced matrix metalloproteinase(MMP)-9, and downregulated chemokine receptors on both B and T cells. Thus statins are effective immunomodulators in vitro that merit evaluation as treatment for MS. In vivo studies using three different animal models of MS revealed that oral atorvastatin prevented or reversed chronic and relapsing paralysis. Atorvastatin has been shown to have pleiotropic immunomodulatory effects involving both antigen presenting cells and T cell compartment. Thus, statins may be beneficial for MS, and clinical trials of the effects of statins on MS are now in progress, hopefully in a favorable way.

Hypercholesterolemia is a major risk factor for the development of coronary heart disease. HMG-CoA reductase inhibitors have been used as first-line drugs because of both their superior cholesterol lowering effect and reliable safety profile. Since there are many patients whose plasma cholesterol level does not reach the therapeutic target even if reductase inhibitors are available, more effective drugs have been strongly required for a long time. Atorvastatin, one of the most recently introduced statins, produces greater plasma LDL-cholesterol reductions than other statins. This pronounced effect of atorvastatin seems to be due to its long-lasting action, presumably a reflection of longer residence time of atorvastatin and its active metabolites in the liver. Clinical trials of atorvastatin have also demonstrated marked plasma triglyceride reductions. The triglyceride reduction with atorvastatin seems to stem from the following two indirect mechanisms, limiting VLDL secretion from the liver and increase in clearance of triglyceride-rich lipoprotein via induced LDL receptors from plasma. Eleven clinical trials of atorvastatin, which have been developed in Japan, clearly demonstrated its ability to reduce LDL-C levels more strongly and in significantly more patients to LDL-C treatment goals than other reductase inhibitors with similar safety profiles. Therefore, atorvastatin adds a new dimension to the effective management of hypercholesterolemia and combined hyperlipidemia.

The development of vasodilator drugs that open the K+ channels in blood vessels has been of great academic and practical interest. The K-channel openers (cromakalim, pinacidil and nicorandil) decreased afterload or preload due to their vasodilator action. In addition, K-channel openers produced a cardioprotective effect in lower doses that did not affect coronary blood flow or blood pressure. It is highly expected to be useful for treatment of congestive heart failure.

Examination was made of cardioprotective effect related to the ATP-sensitive K+ (KATP) channel on isolated globally ischemic reperfused rat hearts using cromakalim, a putative ATP-sensitive K+ channel opener. The hearts were subjected to 20 min Langendorff perfusion with Krebs Henseleit Bicarbonate Buffer (KHBB) (70 cmH2O, 37 degrees C), followed by 30 min ischemia at 36 degrees C, and 30 min reperfusion with KHBB, with (cromakalim group) or without (control group) pretreatment by 10 microM cromakalim added to KHBB for 5 min prior to ischemia. Before ischemia, no significant change in heart rate (HR), left ventricular developed pressure (LVDP) or coronary flow (CF) by 10 microM cromakalim could be detected. The two groups were the same in CF during reperfusion, but recovery of HR and LVDP significantly improved in the cromakalim group. Creatine kinase (CK) leakage in the cromakalim group was significantly less than in the control group during reperfusion. Cromakalim is thus shown to reduce the myocardial injury during ischemia and reperfusion. Intracellular Ca2+ content of the cromakalim group appeared lower than that of the control group at 30 min of reperfusion. At 5-30 min of reperfusion, in the cromakalim group, intracellular Ca2+ storage was prevented, leading to a good recovery of cardiac function, while in the control group, intracellular Ca2+ increased and recovery of cardiac function was poor. After pretreatment with 10 microM cromakalim, intracellular K+ content of the cromakalim group was significantly lower than in the control group before ischemia. At 5 min of reperfusion, intracellular K+ content of the cromakalim group was slightly less than that of the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

The spasmolytic mechanisms of nicorandil, a novel antianginal drug, were investigated using 3,4-diaminopyridine (3,4-DAP)-induced phasic contractions of isolated canine coronary arteries in comparison with those of cromakalim and pinacidil. Nicorandil (10(-4) M), cromakalim (10(-6) M) and pinacidil (10(-5) M) suppressed the phasic contractions. Pretreatment with glibenclamide (10(-6) M), a specific blocking agent of ATP-sensitive K+ channel, eliminated the suppression of phasic contractions by these drugs; glibenclamide completely eliminated the suppression by cromakalim, while the eliminations against nicorandil and pinacidil were incomplete. The recoveries of peak tensions were only 56.8% and 76.1% for nicorandil and pinacidil, respectively. Nicorandil and pinacidil may suppress the phasic contractions via K+ channel opening and additional mechanisms. Methylene blue (10(-7)-10(-5) M) alone, a guanylate cyclase inhibitor, had no effect on the suppression of phasic contractions by nicorandil. In the presence of glibenclamide (10(-6) M), however, the pretreatment with methylene blue significantly augmented the recovery of peak tension for nicorandil. These results indicate that K+ channel openers may suppress the phasic contractions induced by 3,4-DAP via ATP-sensitive K+ channels, and that additionally, nicorandil may suppress the phasic contractility through guanylate cyclase stimulation, as a nitrate.

The ATP-sensitive potassium channel (K+ATP) has been suggested as an important mechanism for the reactivity of vascular smooth muscle. We investigated the effects of K+ channel openers (lemakalim, pinacidil) on hypoxic pulmonary vasoconstriction (HPV) and angiotensin II (Ag II) induced vasoconstriction in isolated rat lungs (Sprague-Dawley rats: 300-450 g). Ventilation with hypoxic gas (2% O2, 5% CO2) was performed for 6 min after the injection of Ag II (0.1 microgram). Isolated lungs were perfused under constant flow (0.04 ml/g/min) using 20 ml of blood from donor rat. The perfusion pressure was used as the pulmonary artery pressure. Lemakalim or pinacidil was pre-administered through the reservoir. Pretreatment with pinacidil (10(-4) M) or lemakalim (10(-5) M) inhibited the pressor response to hypoxia, but did not inhibit the response to angiotensin II. Although the effect of lemakalim on HPV was reversed by administration of glibenclamide (10(-5) M) or tolbutamide (10(-3) M), the effect of pinacidil on HPV was not influenced by either drug. These results suggest that 1) K+ channel openers (lemakalim and pinacidil) inhibit the pressor response to hypoxia, and 2) lemakalim seems to act through K+ATP, whereas pinacidil may have other mechanisms of inhibition of vascular smooth muscle contraction. K+ATP may play an important role in the regulation of pulmonary vascular reactivity to hypoxia.

Anti-inflammatory and gastrointestinal ulcerogenic activities of zomepirac sodium were investigated in experimental animals. The inhibitory activity of zomepirac sodium against carrageenin hind paw edema in rats, acetic acid-induced increase in vascular permeability in mice, and UV-erythema in guinea pigs was more potent than that of indomethacin. Anti-edema activity of zomepirac sodium was seen in adrenalectomized rats. Zomepirac sodium, like indomethacin, inhibited the delayed phase of hind paw edema produced by mixed phlogistics, but not the early phase mediated by histamine and serotonin in rats. Zomepirac sodium produced a dose-dependent inhibition against granuloma formation, established adjuvant arthritis, and development of adjuvant arthritis in rats; and its activity was slightly less potent than that of indomethacin. The inhibitory activity of zomepirac sodium on PGE2 biosynthesis in vitro was about one-third that of indomethacin. The ulcerogenic activity of zomepirac sodium was about 5 times weaker than that of indomethacin. From these results, it was suggested that zomepirac sodium was effective on various types of inflammation and showed particularly potent inhibitory activity against acute inflammation. These findings suggest that the mode of action of zomepirac sodium is similar to that of other acidic non-steroidal anti-inflammatory drugs.

Effect of tolmetin sodium on the pain-like responses caused by various nociceptive stimuli was examined in experimental animals. Tolmetin sodium showed a potent inhibitory activity on the acetic acid-induced writhing in mice and rats, and its potency, (ED50 = 23.4 and 3.01 mg/kg, p.o.) was about 2.4--10.3 times that of ibuprofen and aspirin. The hypertension induced by intraarterial injection of bradykinin toward the spleen of dogs was inhibited by tolmetin sodium (ED50 = 80 mg/kg, i.v.), but the hypertension by a simultaneous injection of bradykinin and PGE1 was not inhibited by tolmetin sodium and sulpyrine, though pentazocine inhibited both hypertensions. The pain-like response caused by pressing mechanically the inflamed paws or joints of rats induced by kaolin-carrageenin or adjuvant was inhibited by tolmetin sodium (30--100 or 20--40 mg/kg, p.o., respectively), and the potency was approximately equal that of ibuprofen and phenylbutazone. Tolmetin sodium produced a significant inhibition of the pain-like response induced by electrical stimulation of tooth pulp of dogs, but showed no effect when the methods of Haffner and D'Amour-Smith were applied to mice. Anti-writhing action of tolmetin sodium was not antagonized by naloxone. From these results, it was concluded that tolmetin sodium has a potent inhibitory activity on the pain-like responses induced by the chemical nociceptive stimuli and by the mechanical pressure stimulus of the inflamed tissue, especially on the writhing. The analgesic activity probably involves a peripheral mechanism.