Downregulation of Mitochondrial Fusion Protein Expression Affords Protection from Canonical Necroptosis in H9c2 Cardiomyoblasts

Necroptosis, a form of necrosis, and alterations in mitochondrial dynamics, a coordinated process of mitochondrial fission and fusion, have been implicated in the pathogenesis of cardiovascular diseases. This study aimed to determine the role of mitochondrial morphology in canonical necroptosis induced by a combination of TNFα and zVAD (TNF/zVAD) in H9c2 cells, rat cardiomyoblasts. Time-course analyses of mitochondrial morphology showed that mitochondria were initially shortened after the addition of TNF/zVAD and then their length was restored, and the proportion of cells with elongated mitochondria at 12 h was larger in TNF/zVAD-treated cells than in non-treated cells (16.3 ± 0.9% vs. 8.0 ± 1.2%). The knockdown of dynamin-related protein 1 (Drp1) and fission 1, fission promoters, and treatment with Mdivi-1, a Drp-1 inhibitor, had no effect on TNF/zVAD-induced necroptosis. In contrast, TNF/zVAD-induced necroptosis was attenuated by the knockdown of mitofusin 1/2 (Mfn1/2) and optic atrophy-1 (Opa1), proteins that are indispensable for mitochondrial fusion, and the attenuation of necroptosis was not canceled by treatment with Mdivi-1. The expression of TGFβ-activated kinase (TAK1), a negative regulator of RIP1 activity, was upregulated and the TNF/zVAD-induced RIP1-Ser166 phosphorylation, an index of RIP1 activity, was mitigated by the knockdown of Mfn1/2 or Opa1. Pharmacological TAK1 inhibition attenuated the protection afforded by Mfn1/2 and Opa1 knockdown. In conclusion, the inhibition of mitochondrial fusion increases TAK1 expression, leading to the attenuation of canonical necroptosis through the suppression of RIP1 activity.

POLD1 Is Required for Cell Cycle Progression by Overcoming DNA Damage in Malignant Pleural Mesothelioma

BACKGROUND/AIM

The prognosis of patients with malignant pleural mesothelioma (MPM) remains poor due to lack of effective therapeutic targets. DNA damage caused by long-time exposure to asbestos fibers has been associated with the development of MPM, with mutations at genes encoding DNA damage repair (DDR)-related molecules frequently expressed in patients with MPM. The present study was designed to identify novel therapeutic targets in MPM using large public databases, such as The Cancer Genome Atlas (TCGA) and Genotype Tissue Expression project (GTEx) focused on DDR pathways.

MATERIALS AND METHODS

The correlations between mRNA expression levels of DDR-related genes and overall survival (OS) were analyzed in mesothelioma patients in TCGA mesothelioma (TCGA-MESO) datasets. The anti-tumor effects of small interfering RNAs (siRNA) against DDR-related genes associated with OS were subsequently tested in MPM cell lines.

RESULTS

High levels of mRNA encoding DNA polymerase delta 1, catalytic subunit (POLD1) were significantly associated with reduced OS in patients with MPM (p<0.001, Log-rank test). In addition, siRNA targeting POLD1 (siPOLD1) caused cell cycle arrest at the G1/S checkpoint and induced apoptosis involving accumulation of DNA damage in MPM cell lines.

CONCLUSION

POLD1 plays essential roles in overcoming DNA damage and cell cycle progression at the G1/S checkpoint in MPM cells. These findings suggest that POLD1 may be a novel therapeutic target in MPM.

Targeting acidic pre-metastatic niche in lungs by pH low insertion peptide and its utility for anti-metastatic therapy

Dysregulated extracellular pH, the universal feature of tumor, works as an evolutional force to drive dissemination of tumor cells. It is well-established that tumor acidity is associated with tumor growth and metastasis. However, the pH of pre-metastatic niche remains unclear. We hypothesized that primary tumor cells remotely prime acidity in secondary organ to achieve metastatic colonization. Herein, we demonstrated that the pH responsive probe pH Low Insertion Peptide (pHLIP) was notably accumulated in pre-metastatic lungs of 4T1.2 breast tumor-bearing mice. The pHLIP-targeted lungs showed high amounts of lactate and overexpressed glycolysis-related proteins. Pharmacological inhibition of glycolysis suppressed the lung acidification induced by 4T1.2 cancer cell culture supernatant and delayed subsequent metastatic burden of disseminated tumor cells. In the acidic lungs, pHLIP was primarily localized in alveolar type 2 cells which strongly expressed glycolysis-related proteins. 4T1.2-derived extracellular vesicles expressed some of the glycolysis-related proteins, and their administration increased pHLIP accumulation and glycolytic enhancement in lungs. pHLIP-conjugated dexamethasone effectively attenuated lung metastatic burden by disrupting pro-inflammatory response in the acidic lungs. From these results, targeting the metastasis-supporting microenvironment by pHLIP technology creates possibility to identify pre-metastatic organ and prevent metastatic recurrence.

Adenosine monophosphate deaminase in the endoplasmic reticulum-mitochondria interface promotes mitochondrial Ca2+ overload in type 2 diabetes rat hearts

AIMS/INTRODUCTION

We previously showed that upregulation of myocardial adenosine monophosphate deaminase (AMPD) is associated with pressure overload-induced diastolic dysfunction in type 2 diabetes hearts. Here, we examined involvement of AMPD localized in the endoplasmic reticulum-mitochondria interface in mitochondrial Ca²⁺ overload and its pathological significance.

MATERIALS AND METHODS

We used type 2 diabetes Otsuka Long-Evans Tokushima Fatty rats (OLETF) and non-diabetes Long-Evans Tokushima Otsuka Fatty rats (LETO) as well as AMPD3-overexpressing H9c2 cells and human embryonic kidney 293 cells.

RESULTS

OLETF, but not LETO, showed diastolic dysfunction under the condition of phenylephrine-induced pressure overload. The levels of 90-kDa AMPD3 in outer mitochondrial membranes/endoplasmic reticulum and mitochondria-associated endoplasmic reticulum membrane (MAM) fractions were significantly higher in OLETF than in LETO. The area of the MAM quantified by electron microscopic analysis was 57% larger, mitochondrial Ca²⁺ level under the condition of pressure overload was 47% higher and Ca²⁺ retention capacity in MAM-containing crude mitochondria isolated before the pressure overloading was 21% lower in OLETF than in LETO (all P-values <0.05). Transfection of FLAG-AMPD3 in cells resulted in significant enlargement of the MAM area, and impairment in pyruvate/malate-driven adenosine triphosphate-stimulated and uncoupler-stimulated mitochondrial respiration compared with those in control cells.

CONCLUSIONS

The findings suggest that 90-kDa AMPD3 localized in the endoplasmic reticulum-mitochondria interface promotes formation of the MAM, inducing mitochondrial Ca²⁺ overload and dysfunction in type 2 diabetes hearts.

Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts

Systemic branched-chain amino acid (BCAA) metabolism is dysregulated in cardiometabolic diseases. We previously demonstrated that upregulated AMP deaminase 3 (AMPD3) impairs cardiac energetics in a rat model of obese type 2 diabetes, Otsuka Long-Evans-Tokushima fatty (OLETF). Here, we hypothesized that the cardiac BCAA levels and the activity of branched-chain α-keto acid dehydrogenase (BCKDH), a rate-limiting enzyme in BCAA metabolism, are altered by type 2 diabetes (T2DM), and that upregulated AMPD3 expression is involved in the alteration. Performing proteomic analysis combined with immunoblotting, we discovered that BCKDH localizes not only to mitochondria but also to the endoplasmic reticulum (ER), where it interacts with AMPD3. Knocking down AMPD3 in neonatal rat cardiomyocytes (NRCMs) increased BCKDH activity, suggesting that AMPD3 negatively regulates BCKDH. Compared with control rats (Long-Evans Tokushima Otsuka [LETO] rats), OLETF rats exhibited 49% higher cardiac BCAA levels and 49% lower BCKDH activity. In the cardiac ER of the OLETF rats, BCKDH-E1α subunit expression was downregulated, while AMPD3 expression was upregulated, resulting in an 80% lower AMPD3-E1α interaction compared to LETO rats. Knocking down E1α expression in NRCMs upregulated AMPD3 expression and recapitulated the imbalanced AMPD3-BCKDH expressions observed in OLETF rat hearts. E1α knockdown in NRCMs inhibited glucose oxidation in response to insulin, palmitate oxidation, and lipid droplet biogenesis under oleate loading. Collectively, these data revealed previously unrecognized extramitochondrial localization of BCKDH in the heart and its reciprocal regulation with AMPD3 and imbalanced AMPD3-BCKDH interactions in OLETF. Downregulation of BCKDH in cardiomyocytes induced profound metabolic changes that are observed in OLETF hearts, providing insight into mechanisms contributing to the development of diabetic cardiomyopathy.

Nuclear translocation of MLKL enhances necroptosis by a RIP1/RIP3-independent mechanism in H9c2 cardiomyoblasts

Accumulating evidence suggests that necroptosis of cardiomyocytes contributes to cardiovascular diseases. Lethal disruption of the plasma membrane in necroptosis is induced by oligomers of mixed lineage kinase domain-like (MLKL) that is translocated to the membrane from the cytosol. However, the role played by cytoplasmic-nuclear shuttling of MLKL is unclear. Here, we tested the hypothesis that translocation of MLKL to the nucleus promotes the necroptosis of cardiomyocytes. Activation of the canonical necroptotic signaling pathway by a combination of TNF-α and zVAD (TNF/zVAD) increased nuclear MLKL levels in a RIP1-activity-dependent manner in H9c2 cells, a rat cardiomyoblast cell line. By use of site-directed mutagenesis, we found a nuclear export signal sequence in MLKL and prepared its mutant (MLKL-L280/283/284A), though a search for a nuclear import signal was unsuccessful. MLKL-L280/283/284A localized to both the cytosol and the nucleus. Expression of MLKL-L280/283/284A induced necroptotic cell death, which was attenuated by GppNHp, an inhibitor of Ran-mediated nuclear import, but not by inhibition of RIP1 activity or knockdown of RIP3 expression. GppNHp partly suppressed H9c2 cell death induced by TNF/zVAD treatment. These results suggest that MLKL that is translocated to the nucleus via RIP1-mediated necroptotic signaling enhances the necroptosis of cardiomyocytes through a RIP1-/RIP3-independent mechanism.

Hypoxia-adapted Multiple Myeloma Stem Cells Resist γδ-T-Cell-mediated Killing by Modulating the Mevalonate Pathway

BACKGROUND/AIM

The prognosis of patients with multiple myeloma (MM) has recently improved due to the emergence of new molecular targeting agents. However, MM remains incurable because MM stem cells are resistant to these agents. Therefore, it is essential to develop strategies to eradicate MM stem cells. We have previously demonstrated that MM cells cultured under prolonged hypoxic conditions (1% O₂) (i.e., hypoxia-adapted MM cells; MM-HA cells) exhibited stem-cell-like characteristics. γδ T cells attack tumor cells by recognizing butyrophilin (BTN) 3A1 and BTN2A1, which are activated by the intracellular accumulation of isopentenyl pyrophosphate (IPP), an intermediate in the mevalonate pathway. In the present study, we investigated the cytotoxicity of γδ T cells against MM-HA stem-like cells.

MATERIALS AND METHODS

We used a combination of flow cytometry, liquid chromatography-tandem mass spectrometry, and western blotting methods to investigate the cytotoxicity of γδ T cells against MM-HA cells and measured the amounts of IPP in MM-HA cells and their supernatants.

RESULTS

The cytotoxicity of γδ T cells against MM-HA cells was significantly lower than that against MM cells cultured under normoxic conditions (20% O₂; MM-Normo). Furthermore, the concentration of IPP in MM-HA cells was lower than that in MM-Normo cells. The expression of mevalonate decarboxylase and farnesyl diphosphate synthase proteins were decreased in MM-HA-cells.

CONCLUSION

The cytotoxicity of γδ T cells against MM-HA cells was suppressed by the reduced IPP accumulation by modulating the mevalonate pathway in MM-HA cells.

Abstract B022: pH-low insertion peptide detects lactic acidosis contributing metastatic niche formation in lungs

Background: Pre-metastatic niche refers to the environment prepared for efficient colonization of disseminated cancer cells in specific organs. Primary tumor secretome facilitates pre-metastatic niche through a series of molecular and cellular changes. This study focuses on interstitial pH in organs with pre-metastatic niche because dysregulated pH homeostasis plays a well-established role in tumor metastasis. In primary tumor, extracellular acidification directly promotes invasion/migration of cancer cells for extravasation. Meanwhile, little is known regarding interstitial pH in organs that are distant from primary tumor. Methods: BALB/c mice were subcutaneously inoculated with 4T1.2 cells or 66cl4 cells (mouse breast cancer cell lines) with resistance against 6-thioguanine. Absence of metastatic cells in their lungs was confirmed by long-termed culture of dissociated pulmonary cells in presence of 6-thioguanine; it defines Day 21 from inoculation as a pre-metastatic phase. Alternatively, 4T1.2 cell-conditioned media (4T1.2-CM) or control media was intraperitoneally administered every day for 21 consecutive days. pH-low insertion peptide (pHLIP® peptide) stably labels cells exposed to acidic conditions, which is feasible to evaluate interstitial acidity in each organ. Alexa Fluor® 750-labelled pHLIP® peptide was injected into mice, and fluorescent signals in harvested organs were detected by IVIS Lumina XRMS Series III. For a metastasis model, mice first received 4T1.2-CM or in combination with sodium oxamate (a lactate dehydrogenase inhibitor) followed by an intravenous injection of 66cl4 cells expressing luciferase. Results: At the pre-metastatic phase, 4T1.2 tumor-bearing mice showed great accumulation of pHLIP® peptide and high amounts of lactate in their lungs. By contrast, there was no significant fluorescence from pHLIP® peptide in lungs of low-metastatic 66cl4 cell-inoculated mice. Notable accumulation of pHLIP® peptide was also observed in the lungs of 4T1.2-CM-given mice. Intravenously injected 66cl4 cells colonized more aggressively in the acidic lungs than in control ones. Suppression of the lung acidification by sodium oxamate attenuated the metastatic burden, which significantly improved survival of the mice. In the acidic lungs, pHLIP® peptide was localized in alveolar type II (AT2) cells expressing surfactant protein C. Sorted AT2 cells from the acidic lungs strongly expressed glycolysis-related proteins. Conclusions: This study using pHLIP® peptide indicates a highly glycolytic activity with increased lactic acid in the lungs of 4T1.2 tumor-bearing mice at the pre-metastatic phase. Mechanistically, soluble factors derived from 4T1.2 cells could transform AT2 cells into acidic cells, which might provide metastasis-promoting function. This study will shed light on understanding the whole picture of pre-metastatic niche and give scientific insights to develop novel diagnosis and therapy for tumor metastasis.

Citation Format: Toma Matsui, Yuki Toda, Anna Mosnikova, Oleg A. Andreev, Shigekuni Hosogi, Yana K. Reshetnyak, Eishi Ashihara. pH-low insertion peptide detects lactic acidosis contributing metastatic niche formation in lungs [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B022.

7,8-Dihydroxy-3-(4'-hydroxyphenyl)coumarin inhibits invasion and migration of osteosarcoma cells

Advances in pharmacy and medicine have led to the development of many anti-cancer and molecular targeted agents; however, there are few agents capable of suppressing metastasis. To prevent cancer recurrence, it is essential to develop novel agents for inhibiting metastasis. Coumarin-based compounds have multiple pharmacological activities including anti-cancer effects. We screened a compound library constructed at Kyoto Pharmaceutical University and showed that 7,8-dihydroxy-3-(4'-hydroxyphenyl)coumarin (DHC) inhibited invasion and migration of LM8 mouse osteosarcoma cells and 143B human osteosarcoma cells in a concentration-dependent manner. DHC decreased intracellular actin filament formation by downregulating Rho small GTP-binding proteins such as RHOA, RAC1, and CDC42, which regulate actin reorganization. However, DHC did not downregulate the corresponding mRNA transcripts, whereas it downregulated Rho small GTP-binding proteins in the presence of cycloheximide, suggesting that DHC enhances the degradation of these proteins. DHC treatment inhibited metastasis and prolonged overall survival in a spontaneous metastasis mouse model. These results indicate that DHC has the potential to suppress metastasis of osteosarcoma cells by downregulating Rho small GTP-binding proteins.

Nuclear accumulation of MLKL induces necroptosis in cardiomyocytes: potential implication in Doxorubicin-induced cardiotoxicity

Background

The treatment with doxorubicin, a powerful chemotherapeutic agent, has been shown to be associated with an increased risk of lethal heart failure. Although various types of cell death pathway such as apoptosis and ferroptosis have been shown to be involved in the development of doxorubicin-induced cardiotoxicity, DIC, the involvement of necroptosis, a novel programmed necrosis induced by translocation of activated mixed lineage kinase domain-like protein, MLKL, to plasma membrane, remains unclear.

Purpose

The aim of this study was to determine whether necroptosis is involved in the development of DIC.

Methods and results

DIC was induced in C57BL/6J mice by intraperitoneal injection of doxorubicin at a dose of 10 mg/kg 3 times for a week. Eight days after the commencement of injection, echocardiographic analyses showed that left ventricular ejection fraction assessed by echocardiography was significantly lower in the doxorubicin-treated mice than in the vehicle-treated mice (44.0±13.7 vs. 70.5±3.7%), indicating the development of DIC. Immunoblot analysis showed that MLKL protein level was higher by 1.6 fold in the doxorubicin-treated mice than in the vehicle-treated mice. Interestingly, immunohistochemical analysis showed that signals of phospho-Ser345-MLKL, an activated form of MLKL, was found in the nuclei in addition to cytosol and intercalated discs of cardiomyocytes in the doxorubicin-treated mice. To get novel insight into significance of nuclear MLKL accumulation, a leucine-rich nuclear export signal (NES) spanning amino acids 280–284 of rat MLKL was identified by site-directed mutation analyses, and H9c2 cells, cultured rat cardiomyoblasts, were transfected with expression constructs for nucleus-directed MLKL (FLAG-mtNES-MLKL) or its wild type (FLAG-WT-MLKL). Percentage of FLAG-positive cells stained with Zombie Red, a fluorescent dye that is non-permeant to live cells, was higher in FLAG-mtNES-MLKL-transfected cells than in FLAG-WT-MLKL-transfected cells (80.0±3.5% vs. 6.3±1.3%, p&lt;0.05), whereas percentage of cells immunostained with cleaved caspase-3 to FLAG-positive cells was similar in the two groups. The effect of the MLKL mutant on necroptosis was attenuated by treatment with GppNHp, an inhibitor of Ran-mediated nuclear protein import.

Conclusion

Nuclear accumulation of MLKL induces necroptosis in cardiomyocytes, which may contribute to progression of DIC.

Funding Acknowledgement

Type of funding sources: None.

Expression of Vincristin-induced Peripheral Neuropathy Related to Different Administration Methods

Vincristine (VCR) is an important drug used in R-CHOP regimens for the treatment of non-Hodgkin's lymphoma. The purpose of this study was to examine whether the administration method affects the incidence of VCR-induced peripheral neuropathy. We investigated the ratio of VCR-induced peripheral neuropathy during rapid intravenous infusion and intravenous drip infusion. A total of 71 patients who had received six or more courses of R-CHOP from January, 2015 to December, 2016 at Komaki City Hospital and Ogaki Municipal Hospital were retrospectively investigated. Peripheral neuropathy was observed in 27/39 patients (69 %) and 24/32 (75 %) in rapid intravenous infusion and intravenous drip infusion of VCR, respectively (P = 0.79). Peripheral neuropathy was observed at a high frequency in this study. Additionally, there was no difference in frequency of peripheral neuropathy due to the difference in administration method. In both groups, the degree of peripheral neuropathy was grade 1 and grade 2 in most patients. However, in rapid intravenous infusion, grade 3 peripheral neuropathy was observed. Some cases required dose reduction and discontinuation in rapid intravenous infusion. In contrast, there were no discontinuing patients in the intravenous drip infusion. Therefore, it was suggested that intravenous drip infusion of VCR reduced serious peripheral neuropathy because the ratio requiring dose reduction and discontinuation was less than that in the rapid group. In conclusion, this study is informative as there are few reports focusing on the administration method of vincristine.

Downregulation of IGFBP5 contributes to replicative senescence via ERK2 activation in mouse embryonic fibroblasts

Insulin-like growth factor (IGF)-binding proteins (IGFBPs) are secretory proteins that regulate IGF signaling. In this study, we investigated the role of IGFBP5 in replicative senescence in embryonic mouse fibroblasts (MEFs). During passages according to the 3T3 method, MEFs underwent senescence after the 5th passage (P5) based on cell growth arrest, an increase in the number of cells positive for senescence-associated β-galactosidase (SA-β-GAL) staining, and upregulation of p16 and p19. In P8 MEFs, IGFBP5 mRNA level was markedly reduced compared with that in P2 MEFs. Downregulation of IGFBP5 via siRNA in P2 MEFs increased the number of SA-β-GAL-positive cells, upregulated p16 and p19, and inhibited cell growth. Incubation of MEFs with IGFBP5 during serial passage increased the cumulative population doubling and decreased SA-β-GAL positivity compared with those in vehicle-treated cells. IGFBP5 knockdown in P2 MEFs increased phosphorylation levels of ERK1 and ERK2. Silencing of ERK2, but not that of ERK1, blocked the increase in the number of SA-β-GAL-positive cells in IGFBP5-knockdown cells. The reduction in the cell number and upregulation of p16 and p21 in IGFBP5-knockdown cells were attenuated by ERK2 knockdown. Our results suggest that downregulation of IGFBP5 during serial passage contributes to replicative senescence via ERK2 in MEFs.

CN470 is a BET/CBP/p300 multi-bromodomain inhibitor and has an anti-tumor activity against MLL-rearranged acute lymphoblastic leukemia

Acute lymphoblastic leukemia with chromosomal rearrangements involving the mixed-lineage leukemia (MLL) gene (MLL-r ALL) remains an incurable disease. Thus, development of a safe and effective therapeutic agent to treat this disease is crucial to address this unmet medical need. BRD4, a member of the bromodomain and extra-terminal domain (BET) protein family, and cyclic AMP response element binding protein binding protein (CBP) and p300, two paralogous histone acetyltransferases, are all considered cancer drug targets and simultaneous targeting of these proteins may have therapeutic advantages. Here, we demonstrate that a BET/CBP/p300 multi-bromodomain inhibitor, CN470, has anti-tumor activity against MLL-r ALL in vitro and in vivo. CN470, potently inhibited ligand binding to the bromodomains of BRD4, CBP, and p300 and suppressed the growth of MLL-r ALL cell lines and patient-derived cells with MLL rearrangements. CN470 suppressed mRNA and protein expression of MYC and induced apoptosis in MLL-r ALL cells, following a cell cycle arrest in the G1 phase. Moreover, CN470 reduced BRD4 binding to acetylated histone H3. The in vivo effects of CN470 were investigated using SEM^Luc/GFP cells expressing luminescent markers in an orthotopic mouse model. Mice administered CN470 daily had prolonged survival compared to the vehicle group. Further, CN470 also showed anti-tumor effects against an MLL-r ALL patient-derived xenograft model. These findings suggest that inhibition of BET/CBP/p300 by the multi-bromodomain inhibitor, CN470, represents a promising therapeutic approach against MLL-r ALL.

Successful Incorporation of Exosome-Capturing Antibody-siRNA Complexes into Multiple Myeloma Cells and Suppression of Targeted mRNA Transcripts

Simple Summary

Although nucleic acid medicines are expected to function as new therapeutic agents, their targeted delivery into cancer cells, particularly hematologic cancer cells, via systemic administration, is limited. Based on our previous finding that tumor cell-derived exosomes are preferentially incorporated into their parental cancer cells, we previously demonstrated that anti-CD63 monoclonal antibody (mAb)-oligonucleotide complexes targeting exosomal microRNAs with linear oligo-D-arginine (Arg) linkers (9mer) were transferred into solid cancer cells and inhibited exosomal miRNA functions. To challenge the delivery of siRNAs into hematologic cancer cells, we developed exosome-capturing anti-CD63 mAb-conjugated small interfering RNAs (siRNA) with branched Arg linkers (9+9mer). Anti-CD63 mAb-conjugated complexes were incorporated into multiple myeloma (MM) cells. Moreover, these exosome-capturing mAb-conjugated siRNAs successfully decreased the mRNA transcript levels of targeted mRNAs in the MM cells. This technology could lead to a breakthrough in drug delivery systems for hematologic cancer therapy.

Abstract

Nucleic acid medicines have been developed as new therapeutic agents against various diseases; however, targeted delivery of these reagents into cancer cells, particularly hematologic cancer cells, via systemic administration is limited by the lack of efficient and cell-specific delivery systems. We previously demonstrated that monoclonal antibody (mAb)-oligonucleotide complexes targeting exosomal microRNAs with linear oligo-D-arginine (Arg) linkers were transferred into solid cancer cells and inhibited exosomal miRNA functions. In this study, we developed exosome-capturing anti-CD63 mAb-conjugated small interfering RNAs (siRNAs) with branched Arg linkers and investigated their effects on multiple myeloma (MM) cells. Anti-CD63 mAb-conjugated siRNAs were successfully incorporated into MM cells. The incorporation of exosomes was inhibited by endocytosis inhibitors. We also conducted a functional analysis of anti-CD63 mAb-conjugated siRNAs. Ab-conjugated luciferase+ (luc+) siRNAs significantly decreased the luminescence intensity in OPM-2-luc+ cells. Moreover, treatment with anti-CD63 mAb-conjugated with MYC and CTNNB1 siRNAs decreased the mRNA transcript levels of MYC and CTNNB1 to 52.5% and 55.3%, respectively, in OPM-2 cells. In conclusion, exosome-capturing Ab-conjugated siRNAs with branched Arg linkers can be effectively delivered into MM cells via uptake of exosomes by parental cells. This technology has the potential to lead to a breakthrough in drug delivery systems for hematologic cancers.

Expression level of BTN3A1 on the surface of CD14+ monocytes is a potential predictor of γδ T cell expansion efficiency

Human γδ T cells expressing Vγ9Vδ2 T cell receptors exert a robust response to pathogens and malignant cells. These cells are activated by BTN3A1, which is expressed by pathogen-derived phosphoantigens (pAgs) or host-derived pAgs that accumulate in transformed cells or in cells exposed to aminobisphosphonates. Activated Vδ2 (+) T cells exert multiple effector functions; therefore, they are a promising candidate for immunotherapy. However, not all donors have γδ T cells with adequate proliferative activity. Here, we performed ex vivo culture of γδ T cells from 20 healthy donors and explored factors that may affect their expansion efficiency. Consistent with previous studies, we found that amplification of γδ T cells requires CD14⁺ monocytes to act as accessory cells. We also show here that surface expression of BTN3A1 by monocytes correlates positively with γδ T cell expansion. Moreover, treatment with BTN3A1-Fc increased the expansion efficiency of peripheral blood mononuclear cells (PBMCs) from donors harboring γδ T cells with poor expansion capacity. Taken together, the data suggest that the level of BTN3A1 expressed on the surface of monocytes is a useful biomarker for predicting the degree of expansion of γδ T cells.

Human Vγ9Vδ2 T cells exert anti-tumor activity independently of PD-L1 expression in tumor cells

Human γδ T cells expressing Vγ9Vδ2 T cell receptors play a crucial role in the innate immune system and have an attracted interest as effector cells in adoptive cellular immunotherapy. However, the efficacy of adoptive cellular immunotherapy for the treatment of tumors requires overcoming the immunosuppressive microenvironment. αβ T cell inhibition in the tumor microenvironment is associated with programmed death-ligand 1 (PD-L1) expression level. Vγ9Vδ2 T cells (abbreviated as γδ T cells here) exert potent cytotoxic effects in various cancers; however, γδ T cell activity in relation to the level of PD-L1 expression in cancer cells remains unclear, and the association between the PD-1/PD-L1 axis and γδ T cell cytotoxicity needs to be investigated. In this study, PD-1 blockade did not increase the cytotoxicity of γδ T cells against PD-L1^high cancer cells. However, the anti-PD-L1 monoclonal antibody (mAb) enhanced the cytotoxicity of γδ T cells against a subset of cancer cells, whereas PD-L1 knockdown did not increase the cytotoxicity of γδ T cells. We also found that the expression levels of PD-L1 were positively correlated with the changes of γδ T cells cytotoxicity induced by anti-PD-L1 mAb. These observations suggest that anti-PD-L1 mAb treatment adds ADCC activity to the cytotoxicity of γδ T cells itself against PD-L1^high cancer cells. The present results suggest that ex vivo expanded γδ T cells have antitumor activity independently of PD-L1 expression and may be promising effector cells for γδ T cell immunotherapy.

Case Report: Disappearance of Coronary Anastomotic Aneurysm by Steroid Therapy in Takayasu Arteritis: Pseudorepair of Pseudoaneurysm?

Background: Takayasu arteritis (TA) is a large vessel vasculitis of unknown etiology characterized by chronic inflammatory changes of the aorta and its major branches. Complications such as anastomotic aneurysm and valve detachment have been reported in active TA patients who received aortic valve replacement and graft replacement of aorta.

Case Summary:A 61-year-old man with a history of emergency aortic valve replacement and patch closure of the noncoronary sinus of Valsalva due to acute heart failure induced by acute aortic regurgitation and ruptured sinus of Valsalva 4 years ago was referred for exertional dyspnea. Dilatation of the sinus of Valsalva together with protrusion of the right sinus of Valsalva and ostial stenosis of the left coronary artery were newly found by computed tomography (CT). A Bentall operation with concomitant coronary artery bypass grafting was successfully performed with a composite graft. Diagnosis of TA was made on the basis of histological analyses of the resected sinus of Valsalva, though other arterial manifestations were not detected by ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography. Three months later, a follow-up study revealed left coronary ostial pseudoaneurysm at the anastomotic site together with strong ¹⁸F-FDG uptake, leading to commencement of steroid therapy. Eight months later, disappearance of left coronary ostial pseudoaneurysm was found by a follow-up CT scan.

Conclusion: This is a rare TA case in whom spontaneous resolution of coronary anastomotic aneurysm by steroid therapy was found without reconstructive surgery.

Factors Associated with Dose Modification of Lenalidomide Plus Dexamethasone Therapy in Multiple Myeloma

Long-term combination treatment with lenalidomide and low-dose dexamethasone is important to achieve a curative effect in patients with multiple myeloma (MM). In this study, the plasma concentration of lenalidomide was measured at 3 h after oral administration, when the drug is in the elimination phase and can be easily measured in outpatients, to identify factors that may lead to the discontinuation of this combination therapy. Patients were assigned to continuation or discontinuation of therapy groups, and the baseline characteristics of patients, lenalidomide concentration, and concentration/dose (C/D) ratios reflecting oral clearance were compared between the two groups. The efficacy and severity of adverse events were also compared. The results showed that patients who discontinued or modified treatment had low plasma concentrations of lenalidomide and C/D ratios, indicating high oral clearance of lenalidomide. The estimated creatinine clearance rate was negatively correlated with the C/D ratio. The plasma concentrations of lenalidomide were independent from kidney function and differed significantly among patients. Taken together, the results indicate that low plasma concentrations of lenalidomide and low C/D ratios may lead to discontinuation of combination therapy in patients with MM. This suggests that early measurement of lenalidomide plasma continuation would help to prevent discontinuation of therapy or a delay in modifying the dose of lenalidomide.

Rhodobacter azotoformans LPS (RAP99-LPS) Is a TLR4 Agonist That Inhibits Lung Metastasis and Enhances TLR3-Mediated Chemokine Expression

The lipopolysaccharides (LPSs) of Rhodobacter are reported to be TLR4 antagonists. Accordingly, the extract of Rhodobacter azotoformans (RAP99) is used as a health supplement for humans and animals in Japan to regulate immune responses in vivo. We previously analyzed the LPS structure of RAP99 (RAP99-LPS) and found it is different from that of E. coli-LPS but similar to lipid A from Rhodobacter sphaeroides (RSLA), a known antagonist of TLR4, with both having three C14 fatty acyl groups, two C10 fatty acyl groups, and two phosphates. Here we show that RAP99-LPS has an immune stimulatory activity and acts as a TLR4 agonist. Pretreatment of RAP99-LPS suppressed E. coli-LPS-mediated weight loss, suggesting it is an antagonist against E. coli-LPS like other LPS isolated from Rhodobacter. However, injections of RAP99-LPS caused splenomegaly and increased immune cell numbers in C57BL/6 mice but not in C3H/HeJ mice, suggesting that RAP99-LPS stimulates immune cells via TLR4. Consistently, RAP99-LPS suppressed the lung metastasis of B16F1 tumor cells and enhanced the expression of TLR3-mediated chemokines. These results suggest that RAP99-LPS is a TLR4 agonist that enhances the activation status of the immune system to promote anti-viral and anti-tumor activity in vivo.

Mouse Bone Marrow-derived Microglia-like Cells Secrete Transforming Growth Factor-β1 and Promote Microglial Aβ Phagocytosis and Reduction of Brain Aβ

Accumulation of amyloid-β (Aβ) in brain tissue contributes to the pathophysiology of Alzheimer's disease (AD). We recently reported that intrahippocampal transplantation of mouse bone marrow-derived microglia-like (BMDML) cells suppresses brain amyloid pathology and cognitive impairment in a mouse model of AD. How these transplanted cells interact with resident microglia remains unknown. In the present study, we evaluated the effects of cytokines secreted from mouse BMDML cells on cultured mouse microglia. Conditioned medium from BMDML cells increased microglial Aβ phagocytosis. High levels of transforming growth factor-β1 (TGF-β1) were present in the conditioned medium, and BMDML cells and microglia expressed Tgf-β1 mRNA and TGF-β receptor type 1 (TGF-βR1) protein, respectively. BMDML conditioned medium also induced microglial Smad2/3 phosphorylation. A TGF-βR1 inhibitor suppressed Smad2/3 phosphorylation and promotion of microglial Aβ phagocytosis induced by conditioned medium. Recombinant mouse TGF-β1 similarly increased microglial Aβ phagocytosis and induced Smad2/3 phosphorylation, which were suppressed by the TGF-βR1 inhibitor. Brain TGF-β1 levels and resident microglial TGF-β1R expression were increased by intrahippocampal injection of BMDML cells in a mouse model of AD. Cotreatment with the TGF-βR1 inhibitor suppressed the ability of transplanted BMDML cells to increase microglial TGF-β1R expression and decrease hippocampal Aβ levels. Taken together, these findings suggested that transplanted BMDML cells secreted TGF-β1 to stimulate Aβ phagocytosis by resident microglia and decrease brain Aβ pathology.

A novel dipeptide type inhibitor of the Wnt/β-catenin pathway suppresses proliferation of acute myelogenous leukemia cells

The Wnt/β-catenin pathway is an attractive target for the treatment of acute myelogenous leukemia (AML), since aberrant activation of the Wnt/β-catenin pathway contributes to carcinogenesis in various types of cancers including AML. Screening of an in-house compound library, constructed at Kyoto Pharmaceutical University, identified a novel compound designated "31" that was found to be an inhibitor of the Wnt/β-catenin pathway. The compound inhibited T-cell factor (TCF) activity in a TCF firefly luciferase-reporter assay and suppressed the proliferation of several human AML cell lines in a dose-dependent manner. Compound 31 arrested the cell cycle of AML cells at the G1 stage and induced apoptosis. Decrease in protein and mRNA expression level of Wnt pathway-related molecules was confirmed by the analyses of western blotting and quantitative reverse transcription-polymerase chain reaction. In addition, compound 31 combined with idarubicin synergistically inhibited the proliferation of AML cells. In conclusion, these results strongly suggest that compound 31 has potential as a novel anti-AML agent targeting the Wnt/β-catenin signaling pathway.

Abstract 643: Cdk4/6 inhibitor Abemaciclib overcomes resistance to BET inhibitor in leukemic cells with MLL-AF5q31 fusion gene

Mixed-lineage leukemia (MLL)-related leukemia which has MLL rearrangement is an intractable disease. Recently, bromodomain and extra-terminal (BET) inhibitors are promising agents, and clinical trials are undergone. However, drug resistance against BET inhibitors has been reported, therefore, it is important to elucidate its mechanism. In this study, we established OTX015-resistant leukemic cells with MLL-AF5q31 fusion gene (OTX015-R cells) and identified molecules that contribute to drug resistance. In addition, we evaluated whether identified molecules are effective as therapeutic target for BET inhibitor-resistant MLL-related leukemia.

To generate OTX015-R cell line, we cultured MLL-AF5q31 cells in the complete medium containing OTX015 with stepwise increasing concentrations. OTX015-R cells exhibited cross-resistance to various BET inhibitors. In addition, protein expressions of bromodomain-containing protein 4 (Brd4) and Brd4-regulated molecules c-Myc, Cdk6 and Bcl-2 were remarkably increased in OTX015-R cells compared with the parental cells. Furthermore, treatment of Cdk4/6 inhibitor Abemaciclib showed a significant antitumor effect on OTX015-R cells and protein expressions of Brd4 and Brd4-regulated molecules were decreased after Abemaciclib treatment. Abemaciclib exhibits antitumor effects on the parental MLL-AF5q31 cells by induction of cell cycle arrest. On the other hand, interestingly, apoptosis in the OTX015-R cells was induced without cell cycle arrest. These results suggest that Abemaciclib induces apoptosis in OTX015-R cells by another mechanism different from cell cycle regulation. We are going to clarify this mechanism.

In conclusion, BET inhibitor-resistant MLL-AF5q31 cells upregulated expression levels of BRD4 and its downstream molecules. We suggest that Cdk6 is a potent therapeutic target for BET inhibitor-resistant MLL-related leukemias.

Citation Format: Keigo Amari, Yuki Toda, Shigekuni Hosogi, Toshihiko Imamura, Eishi Ashihara. Cdk4/6 inhibitor Abemaciclib overcomes resistance to BET inhibitor in leukemic cells with MLL-AF5q31 fusion gene [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 643.

Abstract 1745: Application of BET/CBP/p300 multi-bromodomain inhibitors as a novel therapeutic strategy for MLL-rearranged acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common form of childhood leukemia. While the prognosis of patients with ALL has improved significantly, ALL with chromosomal rearrangements involving mixed-lineage leukemia (MLL) gene remains an incurable disease. Thus, development of a safe and efficacious therapeutic agent based on the biology of MLL rearrangement is of high importance to address this unmet medical need.

Bromodomains are protein motifs that bind to acetylated histones and are recognized as new epigenetic drug targets in recent years. Bromodomain and extra-terminal motif proteins (“BET proteins”) are epigenetic ‘reader' proteins that are characterized by containing two of such bromodomains. BRD4, a member of BET protein family, is a key component of multi-protein complex that induce oncogene transcription at Super-Enhancers. Currently, small-molecule BET inhibitors are being investigated in the clinic as potential therapeutics for hematological cancers. CBP and p300, two paralogous histone acetyltransferases, also contain bromodomains and are considered as drug targets for cancer. Because BET and CBP/p300 proteins are key components of the etiology of MLL-rearranged (MLL-r) leukemia, an agent that simultaneously target both classes of proteins may have therapeutic advantages.

We previously demonstrated that a novel BET inhibitor, CG13250, suppressed multiple myeloma cell proliferation in vitro and in vivo (Biochem Biophys Res Commun, 484:262-268, 2017) and subsequently synthesized additional BET inhibitors (Bioorg Med Chem Lett, 29:1220-1226, 2019). In the present study, we demonstrate that some of our BET inhibitors can also inhibit bromodomains of CBP/p300 proteins. One such compound, CN470, potently suppresses BRD4, CBP, and p300 with BROMOscan KD values of 33, 32, and 20 nM, respectively, and suppressed mRNA and protein expression of c-MYC as expected. CN470 potently inhibited the growth of MLL-r ALL cell lines in a dose-dependent manner and flow cytometric analyses showed that CN470 caused apoptosis in MLL-r ALL cells following a cell cycle arrest at the G1 phase. Moreover, co-immunoprecipitation assay demonstrated that CN470 reduced the binding of BRD4 to acetylated H3 (H3K27), an effect absent with a reference BET inhibitor, OTX-015. Taken together, CN470 may represent an effective strategy against MLL-r ALL cells.

As a confirmatory study, we investigated the in vivo effects of CN470 by using SEMLuc/GFP cells in an orthotopic mouse model of MLL-AF4 leukemia. Mice were orally administered with CN470 (10 mg/kg) once daily resulting in a prolonged survival compared to vehicle control group (mean 37 days vs. 28 days; p=0.0246).

In conclusion, simultaneous inhibition of BET/CBP/p300 with a multi-bromodomain inhibitor represents a promising novel therapeutic approach against MLL-r ALL.

Citation Format: Natsuki Imayoshi, Makoto Yoshioka, Shyh-Ming Yang, Koshi Akahane, Yuki Toda, Shigekuni Hosogi, Takeshi Inukai, Seiji Okada, David J. Maloney, Jefferey W. Strovel, Eishi Ashihara. Application of BET/CBP/p300 multi-bromodomain inhibitors as a novel therapeutic strategy for MLL-rearranged acute lymphoblastic leukemia [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1745.

Association between dipeptidyl peptidase-4 inhibitors and autoimmune disorders: Data mining of the spontaneous reporting system in Japan

The main objective of this study is to conduct a disproportionality analysis of adverse events in the Japan Adverse Event Report (JADER) database and evaluate the risk of the DPP-4 inhibitor induced autoimmune disorder, the secondary objective is risk assessment of sex difference and age difference. The proportional reporting ratio (PRR) of frequency-based statistics and Bayesian estimates of the information components (IC) were calculated as a measure of signal detection. Sex difference and age difference were evaluated using signal score calculated from the PRR and the Chi-square. In patients taking DPP-4 inhibitors, 94 reports of autoimmune disorders were detected with both signals; PRR: 4.09, chi-square: 158.26 and IC: 1.66, 95 % confidence interval: 1.32-2.00). For other antidiabetic drugs, no signals were detected. The signal of males was PRR: 4.53, chi-square: 110.91 and signal score: 6.22, the signal of female was PRR: 3.53, chi-square: 47.65 and signal score: 5.12. About age difference, the signal scores were 6.71 for patients over 60 years and 0.56 for patients under 60 years old. This study suggests that the DPP-4 inhibitors, unlike other antidiabetic drugs, were associated with autoimmune disorders. Signals of the DPP-4 inhibitors induced autoimmune disorders were detected in both male and female, but no sex difference was observed, but age difference was observed. Especially attention should be paid to patients over 60 years old.

6-Hydroxythiobinupharidine Inhibits Migration of LM8 Osteosarcoma Cells by Decreasing Expression of LIM Domain Kinase 1

BACKGROUND/AIM

Osteosarcoma is the most malignant type of bone tumor. Patients with osteosarcoma metastases have a poorer prognosis than those without metastases. Thus, the prognosis of osteosarcoma patients with metastases must be improved.

MATERIALS AND METHODS

The present study investigated the inhibitory effects of 6-hydroxythiobinupharidine isolated from Nuphar pumilum on migration of LM8 murine osteosarcoma cells by a migration assay and also examined the expression of proteins related to actin dynamics by western blot. The present study also developed an automatic cell counting system using machine learning to count migrated cells by Fiji and Trainable Weka Segmentation.

RESULTS

6-Hydroxythiobinupharidine inhibited migration of LM8 osteosarcoma cells in a dose-dependent manner, and decreased protein expression of Lin11, Isl-1, and Mec-3 domain kinase 1 (LIMK1) and the levels of phosphorylated Cofilin.

CONCLUSION

6-Hydroxythiobinupharidine suppressed migration of LM8 osteosarcoma cells by decreasing expression of LIMK1. 6-Hydroxythiobinupharidine could be potentially used as an anti-metastatic compound.

DJ-1 Contributes to Self-renewal of Stem Cells in the U87-MG Glioblastoma Cell Line

BACKGROUND/AIM

DJ-1, an oncogenic molecule, helps to maintain somatic stem cells by reducing the intracellular level of reactive oxygen species (ROS). This study investigated the role of DJ-1 in glioma stem cells (GSCs).

MATERIALS AND METHODS

U87-MG (U87) and U251-MG (U251) glioblastoma cell lines that express wild-type and mutant p53, respectively, were used. These were cultured with DJ-1-targeting siRNA and subjected to a variety of in vitro experiments or intracranial transplantation into nude mice.

RESULTS

Knockdown of DJ-1 reduced clonogenicity only in U87 cells, which was rescued by p53 depletion. ROS accumulated in DJ-1-depleted cells, although treatment with N-acetyl cysteine, which quenches ROS, did not affect exhaustion of CSCs among U87 cells by DJ-1 knockdown. In a serial transplantation study, DJ-1 knockdown prolonged the survival of mice in secondary transplantation.

CONCLUSION

DJ-1 plays a pivotal role in maintenance of stem cell self-renewal in the U87 cell line.

Bone-Marrow-Derived Microglia-Like Cells Ameliorate Brain Amyloid Pathology and Cognitive Impairment in a Mouse Model of Alzheimer's Disease

Microglia, the primary immune cells in the brain, sense pathogens and tissue damage, stimulate cytokine production, and phagocytosis to maintain homeostasis. Accumulation of amyloid-β peptides (Aβ) in the brain triggers the onset of Alzheimer's disease (AD). Accordingly, promotion of Aβ clearance represents a promising strategy for AD therapy. We previously demonstrated that primary-cultured rat microglia phagocytose Aβ, and that transplantation of these cells ameliorates the Aβ burden in brains of Aβ-injected rats. In this study, we demonstrate that stimulation with colony-stimulating factor-1 efficiently differentiates mouse bone marrow cells into bone marrow-derived microglia-like (BMDML) cells that express markers for microglia, including the recently identified transmembrane protein 119. BMDML cells effectively phagocytose Aβ in vitro, with effects comparable to primary-cultured mouse microglia and greater than peritoneal macrophages. RT-qPCR analysis for cytokine mRNA levels revealed that BMDML cells polarize to a relatively anti-inflammatory state under non-stimulated and inflammatory conditions but exert a pro-inflammatory reaction after lipopolysaccharide treatment. Moreover, BMDML cells hippocampally injected into a mouse model of AD are morphologically similar to the ramified and amoeboid types of residential microglia. Comparisons with simulations assuming a uniform distribution of cells suggest that BMDML cells migrate directionally toward Aβ plaques. We also detected Aβ phagocytosis by BMDML cells, concomitant with a reduction in the number and area of Aβ plaques. Finally, we observed amelioration of cognitive impairment in a mouse model of AD after hippocampal injection of BMDML cells. Our results suggest that BMDML cells have potential as a cell-based disease-modifying therapy against AD.

Enhanced immunity in intradermal vaccination by novel hollow microneedles

BACKGROUND

The intradermal (ID) route for vaccination represents an effective alternative to subcutaneous (SC)/intramuscular administration to induce protective immunity. However, a critical issue associated with ID vaccination is the precise delivery of solution in the upper dermis, which ensures enhanced immunity.

METHODS

We fabricated a hollow microneedle unit made of poly-glycolic acid by injection molding and bonding, and created a dedicated prototype injector. To ensure ID delivery of solution, the injected site was macroscopically and microscopically examined. Serum immunoglobulin G antibody production was measured by enzyme immunoassay and compared in groups of rats following either ID delivery with microneedles or SC administration with a 27-G stainless needle of graded vaccine doses.

RESULTS

The unit used a tandem array of six microneedles, each with a side delivery hole, and a conduit inside for solution. Microneedles installed in the injector punctured the skin with the aid of a spring. Injection of solution formed a wheal due to ID distribution. Histologically, a wedge-shaped skin defect in the upper skin corresponded to each puncture site. Antibody titers following vaccinations on days 1 and 8 were significantly higher with ID injection than with SC delivery on day 15 and every 7 days thereafter until day 36 with mumps vaccination, and until day 36 with varicella vaccination.

CONCLUSIONS

The microneedle unit presented here delivered solution intradermally without any difficulty and evoked antibody responses against viruses even with the reduced vaccine volume. Our findings confirm promising results of ID delivery as an immunogenic option to enhance vaccination efficacy.

CG13250, a novel bromodomain inhibitor, suppresses proliferation of multiple myeloma cells in an orthotopic mouse model

Multiple myeloma (MM) is characterized by the clonal proliferation of neoplastic plasma cells. Despite a stream of new molecular targets based on better understanding of the disease, MM remains incurable. Epigenomic abnormalities contribute to the pathogenesis of MM. bromodomain 4 (BRD4), a member of the bromodomain and extraterminal (BET) family, binds to acetylated histones during M/G1 transition in the cell cycle promoting progression to S phase. In this study, we investigated the effects of a novel BET inhibitor CG13250 on MM cells. CG13250 inhibited ligand binding to BRD4 in a dose-dependent manner and with an IC₅₀ value of 1.1 μM. It inhibited MM proliferation in a dose-dependent manner and arrested cells in G1, resulting in the induction of apoptosis through caspase activation. CG13250 inhibited the binding of BRD4 to c-MYC promoter regions suppressing the transcription of the c-MYC gene. Administered in vivo, CG13250 significantly prolonged survival of an orthotopic MM-bearing mice. In conclusion, CG13250 is a novel bromodomain inhibitor that is a promising molecular targeting agent against MM.

Daphnetin inhibits invasion and migration of LM8 murine osteosarcoma cells by decreasing RhoA and Cdc42 expression

Daphnetin, 7,8-dihydroxycoumarin, present in main constituents of Daphne odora var. marginatai, has multiple pharmacological activities including anti-proliferative effects in cancer cells. In this study, using a Transwell system, we showed that daphnetin inhibited invasion and migration of highly metastatic murine osteosarcoma LM8 cells in a dose-dependent manner. Following treatment by daphnetin, cells that penetrated the Transwell membrane were rounder than non-treated cells. Immunofluorescence analysis revealed that daphnetin decreased the numbers of intracellular stress fibers and filopodia. Moreover, daphnetin treatment dramatically decreased the expression levels of RhoA and Cdc42. In summary, the dihydroxycoumarin derivative daphnetin inhibits the invasion and migration of LM8 cells, and therefore represents a promising agent for use against metastatic cancer.

Evidence for carrier localization in the pseudogap state of cuprate superconductors from coherent quench experiments

A 'pseudogap' was introduced by Mott to describe a state of matter that has a minimum in the density of states at the Fermi level, deep enough for states to become localized. It can arise either from Coulomb repulsion between electrons, and/or incipient charge or spin order. Here we employ ultrafast spectroscopy to study dynamical properties of the normal to pseudogap state transition in the prototype high-temperature superconductor Bi2Sr2CaCu2O8+δ. We perform a systematic temperature and doping dependence study of the pseudogap photodestruction and recovery in coherent quench experiments, revealing marked absence of critical behaviour of the elementary excitations, which implies an absence of collective electronic ordering beyond a few coherence lengths on short timescales. The data imply ultrafast carrier localization into a textured polaronic state arising from a competing Coulomb interaction and lattice strain, enhanced by a Fermi surface instability.

Neuroradiological and neurofunctional examinations for patients with 22q11.2 deletion

Since the neuroradiological features of patients with 22q11.2 deletion syndrome are not well-understood, examinations using functional imaging were performed in this study. Brain magnetic resonance imaging (MRI) and 1H-magnetic resonance spectroscopy (MRS) were performed using a clinical 3-Tesla MR imager in 4 patients with 22q11.2 deletion syndrome (2 boys and 2 girls; aged 2-6 years.) and 20 age- and sex-matched healthy control subjects. Furthermore, interictal 123I-iomazenil (IMZ) single photon emission computed tomography (SPECT) was examined in 2 of the 4 patients. Among the 4 patients with 22q11.2 deletion syndrome, 2 patients showed polymicrogyria and 1 patient showed agyria. Those patients with brain malformations also showed abnormal brain artery patterns and decreased accumulation of IMZ in 123I-IMZ SPECT. Although all 4 patients showed epileptic discharges in their electroencephalograms (EEG), one patient with polymicrogyria had no seizure episodes. Decreases in γ-aminobutyric acid (GABA) corresponding to the areas of polymicrogyria and/or epileptic discharges in EEG were shown in all patients except for the patient with agyria. Although consistent evidence was not seen in patients with 22q11.2 deletion syndrome in this study, brain malformations and disturbances of the GABAergic nervous system would be underlying mechanisms of the neurodevelopmental abnormalities in this syndrome.

Femtosecond carrier relaxation dynamics and photoinduced phase separation in κ-(BEDT-TTF)2Cu[N(CN)2]X (X=Br,Cl)

We investigate the relaxation dynamics of nonequilibrium carriers in organic conductors κ-(BEDT-TTF)(2)Cu[N(CN)(2)]X (X=Br and Cl) using ultrafast time-resolved optical spectroscopy. The dynamics for both salts show similar temperature dependences, which is well characterized by the carrier relaxation across the pseudogap (PG) of the magnitude Δ(PG) ≈ 16 meV for Br salt and 7.0 meV for Cl salt. On the other hand, only the Br salt shows an abrupt increase of the decay time at low temperature, indicating an additional decay component associated with the superconducting (SC) gap below T(c). The fluence dependent dynamics at low temperature evidences the superposition of the SC component onto the PG component. These results indicate a metallic-insulating phase separation in the Br salt triggered by photoexcited nonequilibrium carriers.

Click Peptide concept: o-acyl isopeptide of islet amyloid polypeptide as a nonaggregative precursor molecule

The O-acyl isopeptide (1) of islet amyloid polypeptide (IAPP), which contains an ester moiety at both Ala8-Thr9 and Ser19-Ser20, was prepared by sequential segment condensation based on the O-acyl isopeptide method. Isopeptide 1 possessed nonaggregative properties, retaining its random coil structure under the acidic conditions; this suggests that the insertion of the O-acyl isopeptide structures in IAPP suppressed aggregation of the molecule. As a result of the rapid O-to-N acyl shift of 1 under neutral pH, in situ-formed IAPP adopted a random-coil structure at the start of the experiment, and then underwent conformational change to α-helix/β-sheet mixed structures as well as aggregation. The click peptide strategy with the nonaggregative precursor molecule 1 could be a useful experimental tool to identify the functions of IAPP, by overcoming the handling difficulties that arise from IAPP's intense and uncontrollable self-assembling nature.

Chiral charge-density waves

We discovered the chirality of charge-density waves (CDW) in 1T-TiSe₂ by using STM and time-domain optical polarimetry. We found that the CDW intensity becomes Ia₁∶Ia₂∶Ia₃ = 1∶0.7 ± 0.1∶0.5 ± 0.1, where Ia(i) (i=1,2,3) is the amplitude of the tunneling current contributed by the CDWs. There were two states, in which the three intensity peaks of the CDW decrease clockwise and anticlockwise. The chirality in CDW results in the threefold symmetry breaking. Macroscopically, twofold symmetry was indeed observed in optical measurement. We propose the new generalized CDW chirality H(CDW) ≡ q₁·(q₂×q₃), where q(i) are the CDW q vectors, which is independent of the symmetry of components. The nonzero H(CDW)-the triple-q vectors do not exist in an identical plane in the reciprocal space-should induce a real-space chirality in CDW system.

Dynamics of a paired optical vortex generated by second-harmonic generation

We study the dynamics of a paired optical vortex (OV) generated by second-harmonic generation (SHG) using sub-picosecond pulses. By changing the position of a thin nonlinear crystal along the propagation direction, we observe a rotation of two vortices with changing separation distance. The dynamics is well explained by SHG with a beam walk-off, which introduces a contamination of zero-order Laguerre-Gaussian beam (LG(0)) together with topological charge doubling. The quantitative analysis indicates that the rotation angle of the OVs manifests the Gouy phase while the splitting provides the walk-off angle of the crystal. We also show that the subtraction of LG(0) is realized by the superposition of LG(0) with an anti-balanced phase in the pump.

Carrier dynamics in an organic magnetic superconductor and related salts κ, λ-(BETS)(2)MCl(4) (M = Fe, Ga)

In order to compare the carrier dynamics and reveal the origin of differences in their electrical behaviour, time-resolved reflectivity changes were measured on single crystals of the title compounds. The observed relaxation behaviour explained well their electrical behaviour, and indicated that different conduction mechanisms dominated κ- and λ-type BETS salts, irrespective of local spins, at about 8-100 K; the electrical behaviour of the κ-type salts is governed by relaxation times of carriers and/or density of states at the Fermi levels, while that of the λ-type salts is dominated by the latter.

Coherent transfer of orbital angular momentum to excitons by optical four-wave mixing

We demonstrate the coherent transfer of optical orbital angular momentum (OAM) to the center of mass momentum of excitons in semiconductor GaN using a four-wave mixing (FWM) process. When we apply the optical vortex (OV) as an excitation pulse, the diffracted FWM signal exhibits phase singularities that satisfy the OAM conservation law, which remain clear within the exciton dephasing time (approximately 1ps). We also demonstrate the arbitrary control of the topological charge in the output signal by changing the OAM of the input pulse. The results provide a way of controlling the optical OAM through carriers in solids. Moreover, the time evolution of the FWM with OAM leads to the study of the closed-loop carrier coherence in materials.

Preparation and characterization of beta-tricalcium phosphate co-doped with monovalent and divalent antibacterial metal ions

Ag(+) and Zn(2+) or Cu(2+) ions were co-doped with beta-tricalcium phosphate (AgZn-TCP and AgCu-TCP), and their substitution models, antimicrobial activities, mechanisms and cytotoxicities were investigated. The lattice constants (a-axis and c-axis) of AgZn-TCP and AgCu-TCP decreased linearly with the amount of Zn(2+) or Cu(2+) ions up to 9.09 mol.%, which indicated that Ag(+) ions were doped at the Ca(4) site and a vacancy in the beta-TCP structure, and Zn(2+) or Cu(2+) ions were doped at the Ca(5) site. Antibacterial activities of AgZn-TCP and AgCu-TCP on Escherichia coli and Staphylococcus aureus were higher than those of Ag(+) ions-doped beta-TCP (Ag-TCP) and pure beta-TCP. These antimicrobial activities suggested that an interaction occurred between bacteria and Ag(+), Zn(2+) and Cu(2+) ions eluted from AgZn-TCP and AgCu-TCP and between bacteria and the free radicals generated by antibacterial agents or in bacterial cells. AgZn-TCP and AgCu-TCP can be used over long periods of time with high antimicrobial activity, because the rate at which Ag(+) ions are released from AgZn-TCP and AgCu-TCP is slower than that at which Ag(+) ions are released from Ag-TCP. However, it is necessary to determine the suitable amounts of Ag(+), Zn(2+) and Cu(2+) ions in AgZn-TCP and AgCu-TCP by considering both their antimicrobial activities and cytotoxicities, because beta-TCP doped with a large amount of these metal ions exhibits cytotoxicity. Furthermore, AgZn-TCP and AgCu-TCP are considered to be promising materials for use in various fields.

Pressure and magnetic field tuned quantum critical point in the Kondo antiferromagnet CePtZn

We report magnetization, heat capacity and electrical resistivity measurements on CePtZn, which crystallizes in the orthorhombic TiNiSi type structure. Magnetization and electrical resistivity on the iso-structural series of compounds Ce(1-x)La(x)PtZn (x = 0.1, 0.2 0.5 and 1) were also carried out. The electrical resistivity of CePtZn was also measured in external magnetic fields up to 12 T and under pressures up to 2.66 GPa. We find that CePtZn is a dense Kondo lattice, ordering antiferromagnetically at T(N) = 1.7 K, with a comparable Kondo temperature. The magnetic transition temperature, T(N), is continuously suppressed both by the magnetic field and pressure and [Formula: see text] around 5-6 T and at 1.2 GPa, respectively. Non-Fermi liquid behavior of resistivity at 4 T and 1.2 GPa and logarithmic divergence of the heat capacity, C(4f)/T, at 6 T in a limited temperature region strongly suggest the emergence of a quantum critical point as [Formula: see text].

Direct observation of the coexistence of the pseudogap and superconducting quasiparticles in Bi2Sr2CaCu2O8 + y by time-resolved optical spectroscopy

We report the ultrafast optical response of quasiparticles (QPs) in both the pseudogap (PG) and superconducting (SC) states of an underdoped Bi2Sr2CaCu2O8 + y (Bi2212) single crystal measured with the time-resolved pump-probe technique. At a probe energy variant planck's over omegapr = 1.55 eV, it is found that the reflectivity change DeltaR/R changes its sign at exactly Tc, which allows the direct separation of the charge dynamics of PG and SC QPs. Further systematic investigations indicate that the transient signals associated with PG and SC QPs depend on the probe beam energy and polarization. By tuning them below Tc, two distinct components can be detected simultaneously, providing evidence for the coexistence of PG and SC QPs.