Multiple myeloma (MM) cells are characterized by high protein synthesis resulting in chronic endoplasmic reticulum (ER) stress, which is adaptively managed by the unfolded protein response. Inositolrequiring enzyme 1␣ (IRE1␣) is activated to splice X-box binding protein 1 (XBP1) mRNA, thereby increasing XBP1s protein, which in turn regulates genes responsible for protein folding and degradation during the unfolded protein response. In this study, we examined whether IRE1␣- IntroductionTreatment for multiple myeloma (MM) has remarkably improved because of novel agents, such as bortezomib, thalidomide, and lenalidomide. [1][2][3] However, MM remains incurable, and nextgeneration novel agents are urgently needed. Because of high levels of endoplasmic reticulum (ER) stress and adaptation by the unfolded protein response (UPR), targeting signaling by the UPR and blocking this key survival pathway represent a new therapeutic strategy. In mammalian cells, protein folding is proportionally fine-tuned to the metabolic state of the cell within its microenvironment. Extracellular insults, such as low nutrients, hypoxia, and multiple drugs, result in the accumulation of misfolded proteins in the ER, thereby causing ER stress and initiating the UPR. 4 The UPR in turn increases the biosynthetic capacity and decreases the biosynthetic burden of the ER, to maintain cellular homeostasis. However, when the stress cannot be compensated by the UPR, cellular apoptosis occurs. 5 The UPR consists of 3 branches of signaling pathways, which initiate from 3 ER transmembrane proteins: inositol-requiring enzyme 1␣ (IRE1␣), PKR-like ER kinase (PERK), and activating transcription factor 6 (ATF6). In the resting state, these proteins are associated with molecular chaperone BiP/GRP78 in the ER. However, when unfolded proteins accumulate in the ER, BiP/GRP78 dissociates from them, thereby inducing UPR signaling. 6 In the UPR, IRE1␣ is activated by oligomerization and autophosphorylation, resulting in activation of its endoribonuclease to cleave and initiate splicing of the X-box binding protein 1 (XBP1) mRNA. A 26-nucleotide intron from XBP1 is removed by activated IRE1␣ endoribonuclease, resulting in a translational frame-shift to modify unspliced XBP1 (XBP1u: inactive) into spliced XBP1 (XBP1s: active). 7 XBP1 is a unique transcription factor that regulates genes responsible for ER-associated degradation (ERAD), such as EDEM, and those responsible for promoting protein folding, such as p58IPK and other ER chaperones. 8 Thus, IRE1␣-XBP1 pathway has a prosurvival role in the UPR. However, under conditions of prolonged and uncompensated stress, the UPR leads to cellular apoptosis, known as the terminal UPR. The proapoptotic transcription factor CHOP, also known as GADD153, is induced via PERK and ATF6 pathways. CHOP causes downregulation of BCL2, thereby leading to caspase-dependent apoptosis. 9 IRE1␣ also has a proapoptotic role: it binds TRAF2 and activates ASK1, which causes JNK activation, thereby leading to caspase-dependent apoptosis. 10 ...

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Histone deacetylases (HDACs) represent novel molecular targets for the treatment of various types of cancers, including multiple myeloma (MM). Many HDAC inhibitors have already shown remarkable anti-tumor activities in the preclinical setting; however, their clinical utility is limited due to unfavorable toxicities associated with their broad range HDAC inhibitory effects. Isoform-selective HDAC inhibition may allow for MM cytotoxicity without attendant side effects. In this study, we demonstrated that HDAC3 knockdown and a small molecule HDAC3 inhibitor BG45 trigger significant MM cell growth inhibition via apoptosis, evidenced by caspase and PARP cleavage. Importantly, HDAC3 inhibition downregulates phosphorylation (tyrosine 705 and serine 727) of STAT3. Neither IL-6 nor bone marrow stromal cells overcome this inhibitory effect of HDAC3 inhibition on p-STAT3 and MM cell growth. Moreover, HDAC3 inhibition also triggers hyperacetylation of STAT3, suggesting crosstalk signaling between phosphorylation and acetylation of STAT3. Importantly, inhibition of HDAC3, but not HDAC1 or HDAC2, significantly enhances bortezomib-induced cytotoxicity. Finally, we confirm that BG45 alone and in combination with bortezomib trigger significant tumor growth inhibition in vivo in a murine xenograft model of human MM. Our results indicate that HDAC3 represents a promising therapeutic target, and validate a prototype novel HDAC3 inhibitor BG45 in MM.

The bone marrow (BM) microenvironment consists of extracellular-matrix and the cellular compartment including immune cells. Multiple myeloma (MM) cell and BM accessory cell interaction promotes MM survival via both cell-cell contact and cytokines. Immunomodulatory agents (IMiDs) target not only MM cells, but also MM cell-immune cell interactions and cytokine signaling. Here we examined the in vitro effects of IMiDs on cytokine signaling triggered by interaction of effector cells with MM cells and BM stroma cells. IMiDs diminished interleukin-2, interferonγ, and IL-6 regulator suppressor of cytokine signaling (SOCS)1 expression in immune (CD4T, CD8T, natural-killer T, natural-killer) cells from both BM and PB of MM patients. In addition, coculture of MM cells with healthy PBMCs induced SOCS1 expression in effector cells; conversely, treatment with IMiDs down-regulated the SOCS1 expression. SOCS1 negatively regulates IL-6 signaling and is silenced by hypermethylation in MM cells. To define the mechanism of inhibitory-cytokine signaling in effector cells and MM cells, we next analyzed the interaction of immune cells with MM cells that were epigenetically modified to re-express SOCS1; IMiDs induced more potent CTL responses against SOCS1 re-expressing–MM cells than unmodified MM cells. These data therefore demonstrate that modulation of SOCS1 may enhance immune response and efficacy of IMiDs in MM.

Aberrant protein folding beyond the capacity of endoplasmic reticulum (ER) quality control leads to stress response in the ER. The Lys-Asp-Glu-Leu (KDEL) receptor, a retrieval receptor for ER chaperones in the early secretory pathway, contributes to ER quality control. To elucidate the function of the KDEL receptor in vivo, we established transgenic mice expressing a mutant KDEL receptor. We found that the mutant KDEL receptor sensitized cells to ER stress and that the mutant mice developed dilated cardiomyopathy. Ultrastructural analyses revealed expanded sarcoplasmic reticulums and protein aggregates that obstructed the adjacent transverse tubules of the mutant cardiomyocytes. Cardiomyocytes from the mutant mice were sensitive to ER stress when treated with tunicamycin and showed a functional defect in the L-type Ca 2؉ current. We observed ubiquitinated protein aggregates, enhanced expression of CHOP (a death-related transcriptional factor expressed upon ER stress), and apoptosis in the mutant hearts. These findings suggest that impairment of the KDEL receptor disturbs ER quality control, resulting in accumulation of misfolded proteins in the ER in an in vivo system, and that the dilated cardiomyopathy found in the mutant KDEL receptor transgenic mice is associated with ER stress.The endoplasmic reticulum (ER) provides a folding environment for newly synthesized secretory and membrane proteins (10). Aberrant protein folding due to extracellular stimuli, such as ischemia and oxidative stress, and genetic mutation lead to the accumulation of misfolded proteins in the ER, which in turn evokes the unfolded protein response (43), which reduces the amount of misfolded proteins by inducing the production of ER chaperones that promote protein folding, reducing general protein synthesis (16) and enhancing the degradation of misfolded proteins via a ubiquitin-proteasome system termed ER-associated degradation (7, 9, 60). The persistent accumulation of misfolded proteins beyond the capacity of ER quality control causes cellular dysfunction and cell death (24,25,46). This process is involved in diverse human disorders, including diabetes mellitus (14, 42) and neurodegenerative diseases such as Alzheimer's (23) and Parkinson's (20).Misfolded proteins had been believed to remain in the ER, but recent genetic analyses in Saccharomyces cerevisiae have indicated that the unfolded protein response involves the whole secretory pathway (56) and that some misfolded proteins require transport between the ER and the Golgi complex for ER-associated degradation (17,41,53,58). In addition, certain misfolded proteins in mammalian cells have also been reported to exit the ER and recycle between the ER and post-ER compartments, associating with ER chaperones. The KDEL receptor mediates this retrieval, suggesting that the secretion of misfolded proteins from the ER and their retrieval may contribute to ER quality control (12, 62).The KDEL receptor has been identified as a retrieval receptor for luminal ER chaperones that have a carboxyl-te...

The Tohoku region, Northeast Japan, was hit by a gigantic earthquake which occurred in the Pacific close to Tohoku, and subsequently by a giant tsunami. These hazards have caused huge damage on the eastern coast Japan. The earthquake's magnitude was 9.0, the strongest ever recorded in Japan. The tsunami was also historical as its run-up height reached over 39 m. As of early May, 2011, over 24 thousand people were reported as dead or missing. Moreover, serious accidents at the Fukushima Nuclear Power Plants No.1 were caused by the effects of the tsunami. Therefore, the damage faced by Japanese people can be seen as a giant composite disaster. Although Japan, and the northeast of Japan in particular, has over a long time period increased its preparedness against earthquakes and tsunamis, huge damage still occurred. This paper considers why this tragedy occurred, and what unrecognized factors contributed to the high vulnerability of the area. To assist in answering such questions, this paper presents a timely report of the features of the earthquake and tsunami, the damage they caused, and the early efforts for recovery and reconstruction.

An assessment of the vulnerability to sea level rise and climate change was performed for island countries in the South Pacific (Tonga, Fiji, Samoa, and Tuvalu) under the collaboration of Japanese experts and the South Pacific Regional Environment Programme. A combination of experiencebased and scientific methods were developed to reveal the overall vulnerability of and possible impacts on the coastal zone sectors. The studies identified the common impacts on and vulnerability of these countries. Inundation and flooding are the common threats to these islands because of their low-lying setting; the problem is exacerbated by the social trends of population growth and migration to main islands, in particular to the capital cities. Other threats include beach erosion, saltwater intrusion, and impacts on the infrastructure and coastal society. For the island countries, the response to sea level rise and climate change focuses on adaptation rather than on reduction of greenhouse gas emissions (that is, mitigation). Based on the results of the vulnerability assessment, the concept of and options for adaptation are also discussed.

Intervertebral discs of 41 chronic renal failure autopsy cases were examined histologically and immunohistochemically to assess the distribution of beta 2-microglobulin-associated (beta 2m) amyloid in the vertebral column. The results demonstrated beta 2m amyloid to appear first in the cervical discs, then in the lumbar and upper thoracic discs, and finally in the middle and lower thoracic discs as the dialysis period is prolonged. The shortest dialysis period for which beta 2m amyloid was detected was one year and seven months. Deposition of beta 2m amyloid was most remarkable in the C4-5, 5-6, and 6-7 levels, which are known to sustain severe mechanical stress in daily life. Thus it is suggested that local mechanical stress accelerates beta 2m amyloidosis. A marked macrophage reaction was observed around the amyloid in cases of severe amyloidosis, the macrophages themselves being immunohistochemically positive for IL-1 beta and TNF-alpha. Amyloid deposition and reactive inflammation mediated by cytokines appear to be closely related to the pathogenesis of destructive spondyloarthropathy.