A novel 3D mesenchymal stem cell model of the multiple myeloma bone marrow niche: biologic and clinical applications

Specific niches within the tumor bone marrow (BM) microenvironment afford a sanctuary for multiple myeloma (MM) clones due to stromal cell-tumor cell interactions, which confer survival advantage and drug resistance. Defining the sequelae of tumor cell interactions within the MM niches on an individualized basis may provide the rationale for personalized therapies. To mimic the MM niche, we here describe a new 3D co-culture ex-vivo model in which primary MM patient BM cells are co-cultured with mesenchymal stem cells (MSC) in a hydrogel 3D system. In the 3D model, MSC with conserved phenotype (CD73+CD90+CD105+) formed compact clusters with active fibrous connections, and retained lineage differentiation capacity. Extracellular matrix molecules, integrins, and niche related molecules including N-cadherin and CXCL12 are expressed in 3D MSC model. Furthermore, activation of osteogenesis (MMP13, SPP1, ADAMTS4, and MGP genes) and osteoblastogenic differentiation was confirmed in 3D MSC model. Co-culture of patient-derived BM mononuclear cells with either autologous or allogeneic MSC in 3D model increased proliferation of MM cells, CXCR4 expression, and SP cells. We carried out immune profiling to show that distribution of immune cell subsets was similar in 3D and 2D MSC model systems. Importantly, resistance to novel agents (IMiDs, bortezomib, carfilzomib) and conventional agents (doxorubicin, dexamethasone, melphalan) was observed in 3D MSC system, reflective of clinical resistance. This 3D MSC model may therefore allow for studies of MM pathogenesis and drug resistance within the BM niche. Importantly, ongoing prospective trials are evaluating its utility to inform personalized targeted and immune therapy in MM.

Unique anti-myeloma activity by thiazolidine-2,4-dione compounds with Pim inhibiting activity

Proviral Integrations of Moloney virus 2 (PIM2) is overexpressed in multiple myeloma (MM) cells, and regarded as an important therapeutic target. Here, we aimed to validate the therapeutic efficacy of different types of PIM inhibitors against MM cells for their possible clinical application. Intriguingly, the thiazolidine-2,4-dione-family compounds SMI-16a and SMI-4a reduced PIM2 protein levels and impaired MM cell survival preferentially in acidic conditions, in contrast to other types of PIM inhibitors, including AZD1208, CX-6258 and PIM447. SMI-16a also suppressed the drug efflux function of breast cancer resistance protein, minimized the sizes of side populations and reduced in vitro colony-forming capacity and in vivo tumourigenic activity in MM cells, suggesting impairment of their clonogenic capacity. PIM2 is known to be subject to ubiquitination-independent proteasomal degradation. Consistent with this, the proteasome inhibitors bortezomib and carfilzomib increased PIM2 protein levels in MM cells without affecting its mRNA levels. However, SMI-16a mitigated the PIM2 protein increase and cooperatively enhanced anti-MM effects in combination with carfilzomib. Collectively, the thiazolidine-2,4-dione-family compounds SMI-16a and SMI-4a uniquely reduce PIM2 protein in MM cells, which may contribute to their profound efficacy in addition to their immediate kinase inhibition. Their combination with proteasome inhibitors is envisioned.

Effective impairment of myeloma cells and their progenitors by hyperthermia

Multiple myeloma (MM) remains incurable, and MM-initiating cells or MM progenitors are considered to contribute to disease relapse through their drug-resistant nature. In order to improve the therapeutic efficacy for MM, we recently developed novel superparamagnetic nanoparticles which selectively accumulate in MM tumors and extirpate them by heat generated with magnetic resonance. We here aimed to clarify the therapeutic effects on MM cells and their progenitors by hyperthermia. Heat treatment at 43°C time-dependently induced MM cell death. The treatment upregulated endoplasmic reticulum (ER) stress mediators, ATF4 and CHOP, while reducing the protein levels of Pim-2, IRF4, c-Myc and Mcl-1. Combination with the proteasome inhibitor bortezomib further enhanced ER stress to potentiate MM cell death. The Pim inhibitor SMI-16a also enhanced the reduction of the Pim-2-driven survival factors, IRF4 and c-Myc, in combination with the heat treatment. The heat treatment almost completely eradicated "side population" fractions in RPMI8226 and KMS-11 cells and suppressed their clonogenic capacity as determined by in vitro colony formation and tumorigenic capacity in SCID mice. These results collectively demonstrated that hyperthermia is able to impair clonogenic drug-resistant fractions of MM cells and enhance their susceptibility to chemotherapeutic drugs.

A primordial and reversible TCA cycle in a facultatively chemolithoautotrophic thermophile

Inorganic carbon fixation is essential to sustain life on Earth, and the reductive tricarboxylic acid (rTCA) cycle is one of the most ancient carbon fixation metabolisms. A combination of genomic, enzymatic, and metabolomic analyses of a deeply branching chemolithotrophic Thermosulfidibacter takaii ABI70S6^T revealed a previously unknown reversible TCA cycle whose direction was controlled by the available carbon source(s). Under a chemolithoautotrophic condition, a rTCA cycle occurred with the reverse reaction of citrate synthase (CS) and not with the adenosine 5'-triphosphate-dependent citrate cleavage reactions that had been regarded as essential for the conventional rTCA cycle. Phylometabolic evaluation suggests that the TCA cycle with reversible CS may represent an ancestral mode of the rTCA cycle and raises the possibility of a facultatively chemolithomixotrophic origin of life.

A randomized, open-label, phase III trial comparing amrubicin versus docetaxel in patients with previously treated non-small-cell lung cancer

Background

Amrubicin is approved for treating non-small-cell lung cancer (NSCLC) and small-cell lung cancer. However, no direct comparisons between amrubicin and docetaxel, a standard treatment for NSCLC, have been reported.

Patients and methods

We conducted a randomized phase III trial of Japanese NSCLC patients after one or two chemotherapy regimens. Patients were randomized to amrubicin (35 mg/m2 on days 1-3 every 3 weeks) or docetaxel (60 mg/m2 on day 1 every 3 weeks). Outcomes included progression-free survival, overall survival, tumor responses, and safety.

Results

Between October 2010 and June 2012, 202 patients were enrolled across 32 institutions. Median progression-free survival (3.6 versus 3.0 months; P = 0.54) and overall survival (14.6 versus 13.5 months; P = 0.86) were comparable in the amrubicin and docetaxel groups, respectively. The overall response rate was 14.4% (14/97) and 19.6% (19/97) in the amrubicin and docetaxel groups, respectively (P = 0.45). The disease control rate was 55.7% in both groups. Adverse events occurred in all patients, and included grade ≥3 neutropenia occurred in 82.7% and 78.8% of patients in the amrubicin and docetaxel groups, respectively, grade ≥3 leukopenia occurred in 63.3% and 70.7%, and grade ≥3 febrile neutropenia occurred in 13.3% and 18.2% of patients in the amrubicin and docetaxel groups, respectively. Of eight cardiac-related events in the amrubicin group, three were considered related to amrubicin and resolved without treatment discontinuation.

Conclusions

This was the first phase III study to compare amrubicin and docetaxel in patients with pretreated NSCLC. Amrubicin did not significantly improve the primary endpoint of PFS compared with docetaxel.

Clinical trial registration

NCT01207011 (ClinicalTrials.gov).

[Analysis of long-term survivors with cardiac AL amyloidosis]

Cardiac AL amyloidosis (CA) is generally known as a severe disease with very poor prognosis. Here we retrospectively examined seven patients with CA in our cohort who achieved long-term survival. All six patients who underwent high-dose melphalan and autologous stem cell transplantation (ASCT) survived for >3 years, whereas four patients survived for >5 years. Patients who underwent ASCT had prompt hematological responses, and five patients showed organ responses. ASCT helps to achieve a quick and deep hematological response required for long-term survival in patients with CA. New agents have been implemented for the treatment of CA. However, the risks and benefits of each treatment modality should be considered according to patient condition, thus making the best use of ASCT in combination with new agents for the treatment of CA.

HDAC3 regulates DNMT1 expression in multiple myeloma: therapeutic implications

Epigenetic signaling pathways are implicated in tumorigenesis and therefore histone deacetylases (HDACs) represent novel therapeutic targets for cancers, including multiple myeloma (MM). Although non-selective HDAC inhibitors show anti-MM activities, unfavorable side effects limit their clinical efficacy. Isoform- and/or class-selective HDAC inhibition offers the possibility to maintain clinical activity while avoiding adverse events attendant to broad non-selective HDAC inhibition. We have previously reported that HDAC3 inhibition, either by genetic knockdown or selective inhibitor BG45, abrogates MM cell proliferation. Here we show that knockdown of HDAC3, but not HDAC1 or HDAC2, as well as BG45, downregulate expression of DNA methyltransferase 1 (DNMT1) mediating MM cell proliferation. DNMT1 expression is regulated by c-Myc, and HDAC3 inhibition triggers degradation of c-Myc protein. Moreover, HDAC3 inhibition results in hyperacetylation of DNMT1, thereby reducing the stability of DNMT1 protein. Combined inhibition of HDAC3 and DNMT1 with BG45 and DNMT1 inhibitor 5-azacytidine (AZA), respectively, triggers synergistic downregulation of DNMT1, growth inhibition and apoptosis in both MM cell lines and patient MM cells. Efficacy of this combination treatment is confirmed in a murine xenograft MM model. Our results therefore provide the rationale for combination treatment using HDAC3 inhibitor with DNMT1 inhibitor to improve patient outcome in MM.

Ribonucleotide Reductase Catalytic Subunit M1 (RRM1) as a Novel Therapeutic Target in Multiple Myeloma

Purpose: To investigate the biological and clinical significance of ribonucleotide reductase (RR) in multiple myeloma.Experimental Design: We assessed the impact of RR expression on patient outcome in multiple myeloma. We then characterized the effect of genetic and pharmacologic inhibition of ribonucleotide reductase catalytic subunit M1 (RRM1) on multiple myeloma growth and survival using siRNA and clofarabine, respectively, in both in vitro and in vivo mouse xenograft models.Results: Newly diagnosed multiple myeloma patients with higher RRM1 expression have shortened survival. Knockdown of RRM1 triggered significant growth inhibition and apoptosis in multiple myeloma cells, even in the context of the bone marrow microenvironment. Gene expression profiling showed upregulation of DNA damage response genes and p53-regulated genes after RRM1 knockdown. Immunoblot and qRT-PCR analysis confirmed that γ-H2A.X, ATM, ATR, Chk1, Chk2, RAD51, 53BP1, BRCA1, and BRCA2 were upregulated/activated. Moreover, immunoblots showed that p53, p21, Noxa, and Puma were activated in p53 wild-type multiple myeloma cells. Clofarabine, a purine nucleoside analogue that inhibits RRM1, induced growth arrest and apoptosis in p53 wild-type cell lines. Although clofarabine did not induce cell death in p53-mutant cells, it did trigger synergistic toxicity in combination with DNA-damaging agent melphalan. Finally, we demonstrated that tumor growth of RRM1-knockdown multiple myeloma cells was significantly reduced in a murine human multiple myeloma cell xenograft model.Conclusions: Our results therefore demonstrate that RRM1 is a novel therapeutic target in multiple myeloma in the preclinical setting and provide the basis for clinical evaluation of RRM1 inhibitor, alone or in combination with DNA-damaging agents, to improve patient outcome in multiple myeloma. Clin Cancer Res; 23(17); 5225-37. ©2017 AACR.

Wnt5b-associated exosomes promote cancer cell migration and proliferation

Wnt5b is a member of the same family of proteins as Wnt5a, the overexpression of which is associated with cancer aggressiveness. Wnt5b is also suggested to be involved in cancer progression, however, details remain unclarified. We analyzed the biochemical properties of purified Wnt5b and the mode of secretion of Wnt5b by cancer cells. Wnt5b was glycosylated at three asparagine residues and lipidated at one serine residue, and these post-translational modifications of Wnt5b were essential for secretion. Purified Wnt5b showed Dvl2 phosphorylation and Rac activation abilities to a similar extent as Wnt5a. In cultured-cell conditioned medium, Wnt5b was detected in supernatant or precipitation fractions that were separated by centrifugation at 100 000 g. In PANC-1 pancreatic cancer cells, 55% of secreted endogenous Wnt5b was associated with exosomes. Exosomes from wild-type PANC-1 cells, but not those from Wnt5b-knockout PANC-1 cells, activated Wnt5b signaling in CHO cells and stimulated migration and proliferation of A549 lung adenocarcinoma cells, suggesting that endogenous, Wnt5b-associated exosomes are active. The exosomes were taken up by CHO cells and immunoelectron microscopy revealed that Wnt5b is indeed associated with exosomes. In Caco-2 colon cancer cells, most Wnt5b was recovered in precipitation fractions when Wnt5b was ectopically expressed (Caco-2/Wnt5b cells). Knockdown of TSG101, an exosome marker, decreased the secretion of Wnt5b-associated exosomes from Caco-2/Wnt5b cells and inhibited Wnt5b-dependent cell proliferation. Exosomes secreted from Caco-2/Wnt5b cells stimulated migration and proliferation of A549 cells. These results suggest that Wnt5b-associated exosomes promote cancer cell migration and proliferation in a paracrine manner.

Synergistic targeting of Sp1, a critical transcription factor for myeloma cell growth and survival, by panobinostat and proteasome inhibitors

Panobinostat, a pan-deacetylase inhibitor, synergistically elicits cytotoxic activity against myeloma (MM) cells in combination with the proteasome inhibitor bortezomib. Because precise mechanisms for panobinostat's anti-MM action still remain elusive, we aimed to clarify the mechanisms of anti-MM effects of panobinostat and its synergism with proteasome inhibitors. Although the transcription factor Sp1 was overexpressed in MM cells, the Sp1 inhibitor terameprocol induced MM cell death in parallel with reduction of IRF4 and cMyc. Panobinostat induced activation of caspase-8, which was inversely correlated with reduction of Sp1 protein levels in MM cells. The panobinostat-mediated effects were further potentiated to effectively induce MM cell death in combination with bortezomib or carfilzomib even at suboptimal concentrations as a single agent. Addition of the caspase-8 inhibitor z-IETD-FMK abolished the Sp1 reduction not only by panobinostat alone but also by its combination with bortezomib, suggesting caspase-8-mediated Sp1 degradation. The synergistic Sp1 reduction markedly suppressed Sp1-driven prosurvival factors, IRF4 and cMyc. Besides, the combinatory treatment reduced HDAC1, another Sp1 target, in MM cells, which may potentiate HDAC inhibition. Collectively, caspase-8-mediated post-translational Sp1 degradation appears to be among major mechanisms for synergistic anti-MM effects of panobinostat and proteasome inhibitors in combination.

Effective impairment of myeloma cells and their progenitors by blockade of monocarboxylate transportation

Cancer cells robustly expel lactate produced through enhanced glycolysis via monocarboxylate transporters (MCTs) and maintain alkaline intracellular pH. To develop a novel therapeutic strategy against multiple myeloma (MM), which still remains incurable, we explored the impact of perturbing a metabolism via inhibiting MCTs. All MM cells tested constitutively expressed MCT1 and MCT4, and most expressed MCT2. Lactate export was substantially suppressed to induce death along with lowering intracellular pH in MM cells by blockade of all three MCT molecules with α-cyano-4-hydroxy cinnamate (CHC) or the MCT1 and MCT2 inhibitor AR-C155858 in combination with MCT4 knockdown, although only partially by knockdown of each MCT. CHC lowered intracellular pH and severely curtailed lactate secretion even when combined with metformin, which further lowered intracellular pH and enhanced cytotoxicity. Interestingly, an ambient acidic pH markedly enhanced CHC-mediated cytotoxicity, suggesting preferential targeting of MM cells in acidic MM bone lesions. Furthermore, treatment with CHC suppressed hexokinase II expression and ATP production to reduce side populations and colony formation. Finally, CHC caused downregulation of homing receptor CXCR4 and abrogated SDF-1-induced migration. Targeting tumor metabolism by MCT blockade therefore may become an effective therapeutic option for drug-resistant MM cells with elevated glycolysis.

Histone deacetylase inhibitors in multiple myeloma: from bench to bedside

Histone deacetylases (HDACs) deacetylate the lysine residues of both histones and non-histone proteins. Histone acetylation results in a loose local chromatin structure that regulates gene-specific transcription. Non-histone proteins can also be acetylated, leading to dynamic changes in their activity and stability. For these reasons, HDAC inhibition has emerged as a potential approach for the treatment of MM. Specifically, combination treatment with HDAC inhibitors and proteasome inhibitors or immunomodulatory drugs shows remarkable anti-MM activity in both preclinical and clinical settings. However, the clinical studies using non-selective HDAC inhibitors also cause unfavorable side effects in patients, leading us to develop more isoform- and/or class-selective HDAC inhibitors to enhance tolerability without diminishing anti-MM activity, thereby improving patient outcome in MM.

A possible aid in targeted insertion of large DNA elements by CRISPR/Cas in mouse zygotes

The CRISPR/Cas system has rapidly emerged recently as a new tool for genome engineering, and is expected to allow for controlled manipulation of specific genomic elements in a variety of species. A number of recent studies have reported the use of CRISPR/Cas for gene disruption (knockout) or targeted insertion of foreign DNA elements (knock-in). Despite the ease of simple gene knockout and small insertions or nucleotide substitutions in mouse zygotes by the CRISPR/Cas system, targeted insertion of large DNA elements remains an apparent challenge. Here the generation of knock-in mice with successful targeted insertion of large donor DNA elements ranged from 3.0 to 7.1 kb at the ROSA26 locus using the CRISPR/Cas system was achieved. Multiple independent knock-in founder mice were obtained by injection of hCas9 mRNA/sgRNA/donor vector mixtures into the cytoplasm of C57BL/6N zygotes when the injected zygotes were treated with an inhibitor of actin polymerization, cytochalasin. Successful germ line transmission of three of these knock-in alleles was also confirmed. The results suggested that treatment of zygotes with actin polymerization inhibitors following microinjection could be a viable method to facilitate targeted insertion of large DNA elements by the CRISPR/Cas system, enabling targeted knock-in readily attainable in zygotes.

Combination of a Selective HSP90α/β Inhibitor and a RAS-RAF-MEK-ERK Signaling Pathway Inhibitor Triggers Synergistic Cytotoxicity in Multiple Myeloma Cells

Heat shock protein (HSP)90 inhibitors have shown significant anti-tumor activities in preclinical settings in both solid and hematological tumors. We previously reported that the novel, orally available HSP90α/β inhibitor TAS-116 shows significant anti-MM activities. In this study, we further examined the combination effect of TAS-116 with a RAS-RAF-MEK-ERK signaling pathway inhibitor in RAS- or BRAF-mutated MM cell lines. TAS-116 monotherapy significantly inhibited growth of RAS-mutated MM cell lines and was associated with decreased expression of downstream target proteins of the RAS-RAF-MEK-ERK signaling pathway. Moreover, TAS-116 showed synergistic growth inhibitory effects with the farnesyltransferase inhibitor tipifarnib, the BRAF inhibitor dabrafenib, and the MEK inhibitor selumetinib. Importantly, treatment with these inhibitors paradoxically enhanced p-C-Raf, p-MEK, and p-ERK activity, which was abrogated by TAS-116. TAS-116 also enhanced dabrafenib-induced MM cytotoxicity associated with mitochondrial damage-induced apoptosis, even in the BRAF-mutated U266 MM cell line. This enhanced apoptosis in RAS-mutated MM triggered by combination treatment was observed even in the presence of bone marrow stromal cells. Taken together, our results provide the rationale for novel combination treatment with HSP90α/β inhibitor and RAS-RAF-MEK-ERK signaling pathway inhibitors to improve outcomes in patients with in RAS- or BRAF-mutated MM.

Fatal carotid blowout syndrome after BNCT for head and neck cancers

Boron neutron capture therapy (BNCT) is high linear energy transfer (LET) radiation and tumor-selective radiation that does not cause serious damage to the surrounding normal tissues. BNCT might be effective and safe in patients with inoperable, locally advanced head and neck cancers, even those that recur at previously irradiated sites. However, carotid blowout syndrome (CBS) is a lethal complication resulting from malignant invasion of the carotid artery (CA); thus, the risk of CBS should be carefully assessed in patients with risk factors for CBS after BNCT. Thirty-three patients in our institution who underwent BNCT were analyzed. Two patients developed CBS and experienced widespread skin invasion and recurrence close to the carotid artery after irradiation. Careful attention should be paid to the occurrence of CBS if the tumor is located adjacent to the carotid artery. The presence of skin invasion from recurrent lesions after irradiation is an ominous sign of CBS onset and lethal consequences.

Lenalidomide Enhances Immune Checkpoint Blockade-Induced Immune Response in Multiple Myeloma

PURPOSE

PD-1/PD-L1 signaling promotes tumor growth while inhibiting effector cell-mediated antitumor immune responses. Here, we assessed the impact of single and dual blockade of PD-1/PD-L1, alone or in combination with lenalidomide, on accessory and immune cell function as well as multiple myeloma cell growth in the bone marrow (BM) milieu.

EXPERIMENTAL DESIGN

Surface expression of PD-1 on immune effector cells, and PD-L1 expression on CD138(+) multiple myeloma cells and myeloid-derived suppressor cells (MDSC) were determined in BM from newly diagnosed (ND) multiple myeloma and relapsed/refractory (RR) multiple myeloma versus healthy donor (HD). We defined the impact of single and dual blockade of PD-1/PD-L1, alone and with lenalidomide, on autologous anti-multiple myeloma immune response and tumor cell growth.

RESULTS

Both ND and RR patient multiple myeloma cells have increased PD-L1 mRNA and surface expression compared with HD. There is also a significant increase in PD-1 expression on effector cells in multiple myeloma. Importantly, PD-1/PD-L1 blockade abrogates BM stromal cell (BMSC)-induced multiple myeloma growth, and combined blockade of PD-1/PD-L1 with lenalidomide further inhibits BMSC-induced tumor growth. These effects are associated with induction of intracellular expression of IFNγ and granzyme B in effector cells. Importantly, PD-L1 expression in multiple myeloma is higher on MDSC than on antigen-presenting cells, and PD-1/PD-L1 blockade inhibits MDSC-mediated multiple myeloma growth. Finally, lenalidomide with PD-1/PD-L1 blockade inhibits MDSC-mediated immune suppression.

CONCLUSIONS

Our data therefore demonstrate that checkpoint signaling plays an important role in providing the tumor-promoting, immune-suppressive microenvironment in multiple myeloma, and that PD-1/PD-L1 blockade induces anti-multiple myeloma immune response that can be enhanced by lenalidomide, providing the framework for clinical evaluation of combination therapy.

Organ specificity in autoimmune diseases: thyroid and islet autoimmunity in alopecia areata

CONTEXT

Multiple autoimmune diseases, such as autoimmunity against the thyroid gland and pancreatic islets, are often observed in a single patient. Although alopecia areata (AA) is one of the most frequent organ-specific autoimmune diseases, the association of AA with other autoimmune diseases and the genetic basis of the association remain to be analyzed.

OBJECTIVE

The aim of this study was to clarify the similarities and differences in HLA and clinical characteristics of thyroid and islet autoimmunity in patients with AA.

PARTICIPANTS

A total of 126 patients with AA were newly recruited. Anti-islet and antithyroid autoantibodies were tested, and genotypes of HLA genes were determined.

RESULTS

Among the autoimmune diseases associated with AA, autoimmune thyroid disease was most frequent (10.0%), followed by vitiligo (2.7%) and rheumatoid arthritis (0.9%) but not type 1 diabetes (0.0%). The prevalence of thyroid-related autoantibodies in patients with AA was significantly higher than that in controls (TSH receptor antibody [TRAb]: 42.7% vs 1.2%, P = 1.6 × 10(-46); thyroid peroxidase antibody: 29.1% vs 11.6%; P = 1.7 × 10(-6)), whereas the prevalence of islet-related autoantibodies was comparable between patients with AA and control subjects. The frequency of DRB1*15:01-DQB1*06:02, a protective haplotype for type 1 diabetes, was significantly higher in TRAb-positive (12.8%, P = .0028, corrected P value [Pc] = .02) but not TRAb-negative (7.1%, not significant) patients with AA than in control subjects (4.5%). The frequency of DRB1*04:05-DQB1*04:01, a susceptible haplotype for type 1 diabetes, was significantly lower in patients with AA (TRAb-positive: 8.5%; TRAb-negative: 11.9%) than in those with type 1 diabetes (29.5%, Pc < .0003 and Pc < .0008, respectively).

CONCLUSION

AA was associated with thyroid autoimmunity but not islet autoimmunity, which correlated with class II HLA haplotypes susceptible or resistant to each autoimmune disease.

Spermidine promotes retinal ganglion cell survival and optic nerve regeneration in adult mice following optic nerve injury

Spermidine acts as an endogenous free radical scavenger and inhibits the action of reactive oxygen species. In this study, we examined the effects of spermidine on retinal ganglion cell (RGC) death in a mouse model of optic nerve injury (ONI). Daily ingestion of spermidine reduced RGC death following ONI and sequential in vivo retinal imaging revealed that spermidine effectively prevented retinal degeneration. Apoptosis signal-regulating kinase-1 (ASK1) is an evolutionarily conserved mitogen-activated protein kinase kinase kinase and has an important role in ONI-induced RGC apoptosis. We demonstrated that spermidine suppresses ONI-induced activation of the ASK1-p38 mitogen-activated protein kinase pathway. Moreover, production of chemokines important for microglia recruitment was decreased with spermidine treatment and, consequently, accumulation of retinal microglia is reduced. In addition, the ONI-induced expression of inducible nitric oxide synthase in the retina was inhibited with spermidine treatment, particularly in microglia. Furthermore, daily spermidine intake enhanced optic nerve regeneration in vivo. Our findings indicate that spermidine stimulates neuroprotection as well as neuroregeneration, and may be useful for treatment of various neurodegenerative diseases including glaucoma.

Class IIa HDAC inhibition enhances ER stress-mediated cell death in multiple myeloma

Histone deacetylase (HDAC) inhibitors have been extensively investigated as therapeutic agents in cancer. However, the biological role of class IIa HDACs (HDAC4, 5, 7 and 9) in cancer cells, including multiple myeloma (MM), remains unclear. Recent studies show HDAC4 interacts with activating transcription factor 4 (ATF4) and inhibits activation of endoplasmic reticulum (ER) stress-associated proapoptotic transcription factor C/EBP homologous protein (CHOP). In this study, we hypothesized that HDAC4 knockdown and/or inhibition could enhance apoptosis in MM cells under ER stress condition by upregulating ATF4, followed by CHOP. HDAC4 knockdown showed modest cell growth inhibition; however, it markedly enhanced cytotoxicity induced by either tunicamycin or carfilzomib (CFZ), associated with upregulating ATF4 and CHOP. For pharmacological inhibition of HDAC4, we employed a novel and selective class IIa HDAC inhibitor TMP269, alone and in combination with CFZ. As with HDAC4 knockdown, TMP269 significantly enhanced cytotoxicity induced by CFZ in MM cell lines, upregulating ATF4 and CHOP and inducing apoptosis. Conversely, enhanced cytotoxicity was abrogated by ATF4 knockdown, confirming that ATF4 has a pivotal role mediating cytotoxicity in this setting. These results provide the rationale for novel treatment strategies combining class IIa HDAC inhibitors with ER stressors, including proteasome inhibitors, to improve patient outcome in MM.

Effect of three-size too large strong stocking on venous hemodynamics in normal subjects

OBJECTIVES

To study the differences in impact on venous hemodynamics between larger size strong graduated elastic compression stockings (GECS) and appropriate size strong/moderate GECS.

METHOD

In healthy legs fitted for a small (Group S; n = 8) and large (Group L; n = 8) GECS, air plethysmography was performed without GECS, with an appropriate size strong GECS (GECS1), with a three-size too large strong GECS (GECS2), and with an appropriate size moderate GECS (GECS3) in this order.

RESULTS

In Group S, interface pressure with GECS2 was equal to or higher than that with GECS3. Decreased venous volume, unchanged ejection volume, and decreased residual volume were achieved by GECS, but differences in these parameters among GECS were not observed. Although insignificant, a similar tendency was found in Group L.

CONCLUSIONS

A larger size strong GECS seemed to have equivalent interface pressure and impact on venous hemodynamics compared to an appropriate size moderate or strong GECS.