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Various derivatives of thalidomide, a drug that is well-known for its teratogenicity, have recently been developed; among them, lenalidomide and pomalidomide, known as immunomodulatory drugs (IMiDs), have potent anticancer activity. These drugs have been approved by Food and Drug Administration for the treatment of several diseases, including multiple myeloma, under strict control. The primary direct target protein of thalidomide and IMiDs is cereblon (CRBN), a substrate receptor of Cullin-RING ligase 4 (CRL4). CRL4 CRBN is a unique E3 ubiquitin ligase because its substrate selectivity is altered by ligands such as IMiDs. Each IMiD induces degradation of neosubstrates, such as Ikaros or CK1a. Because the activity of new CRBN-binding compounds is not limited to immunomodulation, the designation of "cereblon modulators" has been proposed for these small CRBN-binding compounds. Currently, researchers are investigating CC-122 (avadomide) and CC-220 (iberdomide) for the treatment of diffuse large B-cell lymphoma and systemic lupus erythematosus, respectively. Other recent studies have been investigating heterobifunctional molecules called proteolysis-targeting chimeras (PROTACs) for protein of interest degradation. Moreover, several proteins, such as BRD4, CDK9, or Tau, have already been successfully degraded by CRBN-based PROTACs. In this review, recent advances in CRBN and its binding compounds have been discussed.

Immunomodulatory drugs (IMiDs) are a new class of anticancer compounds that are derived from thalidomide. Lenalidomide and pomalidomide are well-known IMiDs, and they have already been approved by FDA for the treatment of several diseases, including multiple myeloma. Cereblon (CRBN) is a common primary target for IMiDs. It works as a substrate receptor of CRL4. Accumulating evidence has shown that the substrate specificity of CRL4 CRBN is altered by ligands such as IMiDs. Recently, novel CRBN-binding compounds have been developed and are called "cereblon modulators". Among these, CC-122 and CC-220 are currently under clinical development for the treatment of diffuse large B-cell lymphoma and systemic lupus erythematosus, respectively. Another new cereblon modulator CC-885 is shown to induce degradation of the translation termination factor GSPT1, resulting in an antiproliferative effect in acute myeloid leukemia. Structural analyses have revealed that CC-885 provides an interaction hotspot between CRBN and GSPT1. On the other hand, several groups have been investigating linker-based approaches for targeted protein degradation via CRBN. Several proteins, such as BRD4 and BCR-ABL, have been successfully degraded by CRL4 CRBN using these technologies. In this review, we introduce recent topics in CRBN and its binding compounds.

Half a century ago, the sedative thalidomide caused a serious drug disaster because of its teratogenicity and was withdrawn from the market. However, thalidomide, which has returned to the market, is now used for the treatment of leprosy and multiple myeloma (MM) under strict control. The mechanism of thalidomide action had been a long-standing question. We developed a new affinity bead technology and identified cereblon (CRBN) as a thalidomide-binding protein. We found that CRBN functions as a substrate receptor of an E3 cullin-Ring ligase complex 4 (CRL4) and is a primary target of thalidomide teratogenicity. Recently, new thalidomide derivatives, called immunomodulatory drugs (IMiDs), have been developed by Celgene. Among them, lenalidomide (Len) and pomalidomide (Pom) were shown to exert strong therapeutic effects against MM. It was found that Len and Pom both bind CRBN-CRL4 and recruit neomorphic substrates (Ikaros and Aiolos). More recently it was reported that casein kinase 1a (Ck1a) was identified as a substrate for CRBN-CRL4 in the presence of Len, but not Pom. Ck1a breakdown explains why Len is specifically effective for myelodysplastic syndrome with 5q deletion. It is now proposed that binding of IMiDs to CRBN appears to alter the substrate specificity of CRBN-CRL4. In this review, we introduce recent findings on IMiDs.

DNA methylation is one of the major epigenetic marks in the mammalian genome to define chromatin higher-order structure, and plays essential roles in various developmental processes. In the mammalian genome, DNA methylation mainly occurs at the 5th position of cytosine bases in a palindromic 5'-CG-3'dinucleotide sequence. Methyl CpG binding domain (MBD) proteins recognize symmetrically methylated CpG sites (5mCG/5mCG) through a conserved MBD, and recruit transcriptional repressors or chromatin modifiers. One of the MBD proteins, MBD4, uniquely contains a C-terminal glycosylation domain together with an N-terminal MBD, and functions as a mismatch DNA repair enzyme specific for T/G or U/G mismatch bases generated by spontaneous deamination of 5-methylcytosine. The base excision activity of MBD4 is also implicated in active DNA demethylation initiated by the conversion of 5-methylcytosine to thymine by deaminases. Unlike other MBD proteins, MBD4 recognizes not only 5mCG/5mCG but also T/G mismatched sites generated by spontaneous deamination of 5-methylcytosine (5mCG/TG). In addition, our biochemical data demonstrate that MBD also binds to intermediates in DNA demethylation pathways, such as 5-hydroxymethyl-cytosine (hmC), 5-carboxyl-cytosine and 5-hydroxy-uracil. The crystal structures of MBDMBD4 in complex with 5mCG/TG, 5mCG/5mCG or 5mCG/hmCG provide new structural insights into the versatility of base recognition by MBD4. A DNA interface of MBD4 has flexible structural features, in which an extensive hydration water network supports the versatile base specificity of MBD4. The versatile base recognition by MBDMBD4 implies multi-functional roles of MBD4 in the regulation of dynamic DNA methylation patterns.

G(M1)-gangliosidosis and Morquio B are rare lysosomal storage diseases associated with a neurodegenerative disorder or dwarfism and skeletal abnormalities, respectively. These diseases are caused by deficiencies in the lysosomal enzyme human β-D-galactosidase (h-β-GAL), which lead to accumulations of the h-β-GAL substrates, G(M1) ganglioside and keratan sulfate due to mutations in the h-β-GAL gene. H-β-GAL is an exoglycosidase that catalyzes the hydrolysis of terminal β-linked galactose residues. Here, we present the crystal structures of h-β-GAL in complex with its catalytic product galactose or with its inhibitor 1-deoxygalactonojirimycin. H-β-GAL showed a novel homodimer structure; each monomer was comprised of a catalytic TIM barrel domain followed by β-domain 1 and β-domain 2. The long loop region connecting the TIM barrel domain with β-domain 1 was responsible for the dimerization. To gain structural insight into the molecular defects of h-β-GAL in the above diseases, the disease-causing mutations were mapped onto the three-dimensional structure. Finally, the possible causes of the diseases are discussed.

The worldwide distribution of smokable herbal mixtures called "Spice" that contain synthetic cannabinoids with a pharmacological activity similar to delta 9-tetrahydrocannabinol (delta 9-THC) has been reported. The synthetic cannabinoids induce behavior and have biochemical properties similar to naturally occurring cannabinoids such as delta 9-THC. In drug discrimination procedures, animal behavior is differentially reinforced depending on the presence or absence of specific drug stimuli. This review seeks to establish an animal model to serve as a discriminative stimulus of the synthetic cannabinoids, to determine whether this discriminative stimulus is identical to that of delta 9-THC. Much data have been obtained in drug discrimination experiments with various synthetic cannabinoids. In the discriminative study, synthetic cannabinoids such as CP-55,940 and WIN-55,212-2 were substituted for delta 9-THC in rats trained to discriminate delta 9-THC from the vehicle. These discriminative effects of synthetic cannabinoids were antagonized by CB1 antagonist SR-141,716A. The discriminative effects of synthetic cannabinoids may overlap with the delta 9-THC cue mediated by CB1 receptors. In in vitro study using NG 108-15 cell lines, synthetic cannabinoids have produced strong cytotoxicities that were suppressed by pretreatment with the CB1 receptor antagonist. Furthermore, pretreatment with caspase inhibitors suppressed these synthetic-cannabinoid-induced cytotoxicities in NG 108-15 cells. These findings indicate that the cytotoxicity of synthetic cannabinoids towards NG 108-15 cells is mediated by the CB1 receptors and further suggest that caspase cascades may play an important role in the cytotoxicities induced by these synthetic cannabinoids. In conclusion, synthetic cannabinoid abuse could be a health hazard for humans.

Platinum agents are widely used in cancer chemotherapy. Cisplatin, carboplatin, oxaliplatin and nedaplatin have a common chemical structure consisting of platinum, carrier groups and leaving groups, and undergo the similar mechanism of cytotoxicity. Only cisplatin induces nephrotoxicity, although the molecular mechanism involved is unclear. Organic cation transporter (OCT)/SLC22A, and multidrug and toxin extrusion (MATE)/SLC47A play a role in renal handling of cationic drug in the kidney. We focused on a role of transporters in nephrotoxicity of platinum agents. OCT2 mediates the transport of cisplatin and is the determinant of cisplatin-induced nephrotoxicity. In addition, MATE1 protects cisplatin-induced nephrotoxicity. Oxaliplatin, which was a superior substrate of the luminal efflux transporter, MATE2-K as well as OCT2, did not show nephrotoxicity. Moreover, carboplatin and nedaplatin were not transported by these transporters. Substrate specificity could regulate the features of platinum agents. Recent findings indicate that organic cation transporters are key to the nephrotoxicity of platinum agents.

Aeromonas species are Gram-negative facultative anaerobic bacteria found ubiquitously in a variety of aquatic environments and most commonly implicated as causative agents of gastroenteritis. Sepsis is a fatal complication of Aeromonas infectious diseases, particularly in immune-compromised patients. Two species, Aeromonas hydrophila and Aeromonas sobria, are associated with human disease. Feasible virulence factors of Aeromonas include fimbrial and afimbrial adhesion molecules, hemolysins, enterotoxins, lipases and proteases. Recently, we purified a 65-kDa A. sobria serine protease (ASP) from the culture supernatant of A. sobria and found that the enzyme induces vascular leakage and reduces blood pressure through activation of the kallikrein/kinin system. This ASP activity potentially contributes to the onset of septic shock, suggesting ASP as an important virulence factor. In this review, I describe both the substrate specificity and the structural property of ASP. Furthermore, I also discuss the maturation mechanism of ASP. Further studies will facilitate development of novel drugs for bacterial infection that have inhibitory effects on various serine proteases.

According to the results of Japanese phase III trials recently reported such as JCOG 9912 and SPIRITS, there was a remarkable improvement in median survival time compared to the previous phase III study(JCOG 9205). Many newer agents were used, such as taxane and irinotecan, which were absent during JCOG 9205. Using these agents as a second- line treatment may lead to improved survival. However, there is no evidence of a randomized control trial of second-line treatment. At present, several study groups are conducting randomized control trials to establish a standard for second-line therapy. However, there are several issues regarding the study design, especially a control arm. In future trials, we should exchange information among study groups to discuss the important issues involved. On the other hand, molecular targeting agents that have shown activity in other tumor types such as trastuzumab, bevacizumab, cetuximab, and lapatinib are under investigation in global randomized control trials. In these trials, patients from Japan and Korea account for more than half of the enrollees. The number of international studies is increasing, and the role of east Asian countries will be more important in this field.

Replication-selective tumor-specific viruses present a novel approach for treatment of neoplastic disease. Telomerase activation is considered to be a critical step in carcinogenesis, and its activity correlates closely with human telomerase reverse transcriptase(hTERT)expression. We constructed an attenuated adenovirus 5 vector(Telomelysin, OBP-301), in which the hTERT promoter element drives expression of E1 genes. Telomelysin replicated efficiently and induced marked cell killing in a panel of human cancer cell lines, whereas replication as well as cytotoxicity was highly attenuated in normal human cells lacking telomerase activity. We further modified the E3 region of OBP-301 to contain green fluorescent protein(GFP)gene for monitoring viral replication(TelomeScan, OBP-401). When TelomeScan was intratumorally injected into human tumors orthotopically implanted into the rectum in mice, para-aortic lymph node metastasis could be visualized at laparotomy with a three-chip color cooled charged-coupled device camera. This article reviews recent highlights in this rapidly evolving field of cancer therapeutic and diagnostic approaches using telomerase-specific oncolytic adenoviruses.