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Macrophages (Mϕ) are highly plastic and change their functional phenotypes depending on microenvironmental signals. Recent studies have shown that microRNAs are involved in the polarization of Mϕ. In this study, we demonstrated that the phenotype of M2bMϕ [CCL1(+) IL-10(+) LIGHT(+)] switches to other phenotypes with interchangeability attained through the increased expression of growth arrest-specific 5 RNA (GAS5 RNA), a long noncoding RNA. GAS5 RNA has been described as a silencer of the CCL1 gene. Various phenotypes of Mϕ were prepared from bone marrow-derived Mϕ (BMDMϕ) after stimulation with IFNγ [M(IFNγ)/M1Mϕ], IL-4 [M(IL-4)/M2aMϕ], LPS and immobilized IgG [M(LPS + IC)/M2bMϕ], and IL-10 [M(IL-10)/M2cMϕ]. BMDMϕ cultured with medium [M(no)/quiescent Mϕ] were used as a control. As compared to Μ(no), M(IFNγ), M(IL-4) and M(IL-10), the reduced level of GAS5 RNA was shown in M(LPS + IC). CCL1 and LIGHT mRNAs (typical biomarkers of M2bMϕ) were not expressed by M(LPS + IC) transduced with a GAS5 gene using lentiviral vector. The reduction of GAS5 RNA in M(LPS + IC) was mediated by the activation of nonsense-mediated RNA decay (NMD) pathway. BMDMϕ overexpressed with GAS5 RNA after GAS5 gene transduction did not polarize to M2bMϕ even though they were stimulated with LPS and IC in combination. These results indicate that the reduction of GAS5 RNA influenced by the NMD pathway activation leads to the Mϕ polarization stimulated with LPS and IC in combination. [ABSTRACT FROM AUTHOR]

Abstract: Increasing evidence indicates that phospholipid oxidation plays important roles in atherosclerosis. Here, we investigated the involvement of Rho-family GTPases inphosphatidylcholine hydroperoxide (PCOOH)-induced THP-1 cell adhesion to ICAM-1. Isoprenoid depletion by fluvastatin and geranylgeranyltransferase inhibition by GGTI-286 suppressed PCOOH-induced cell adhesion to ICAM-1 and F-actin-rich membrane protrusion formation. Pull-down assays demonstrated the activation of Rac1 and Rac2 in PCOOH-treated cells. Pan-Rho-family GTPase inhibitor Clostridium difficile toxin B, Rac-specific inhibitor NSC23776, and RNA interference of the Rac isoforms suppressed the cell adhesion. These findings indicate the involvement of Rac GTPase activation in PCOOH-induced cell adhesion to ICAM-1 via actin reorganization. [Copyright &y& Elsevier]

Kinesin centromere-associated protein E (CENP-E) has emerged as a potential target for the development of anticancer drugs due to its involvement in the mitotic progression of the cell cycle. Although several CENP-E inhibitors have been reported, more knowledge of chemical structures and inhibitory mechanisms is necessary for developing CENP-E inhibitors. Here, we describe the identification of new CENP-E inhibitors. Screening of a small-molecule chemical library identified benzo[ d ]pyrrolo[2,1- b ]thiazole derivatives, including 1 , as compounds with inhibitory activity against the microtubule-stimulated ATPase of the CENP-E motor domain. Among the mitotic kinesins examined, 1 selectively inhibited the kinesin ATPase activity of CENP-E. In a steady-state ATPase assay, 1 exhibited ATP-competitive behavior, which was different from the CENP-E inhibitor GSK923295. Compound 1 inhibited the proliferation of tumor-derived HeLa and HCT116 cells more efficiently than that of non-cancerous WI-38 cells. The inhibition of cell proliferation was attributed to the ability of 1 to induce apoptotic cell death. The compound showed antimitotic activity, which caused cell cycle arrest at mitosis via interference with proper chromosome alignment. We identified 1 and its derivatives as the lead compounds that target CENP-E, thus providing a new opportunity for the development of anticancer agents targeting kinesins. Image 1 • New CENP-E inhibitors with benzo[ d ]pyrrolo[2,1- b ]thiazole structure were discovered. • One of the inhibitors prevents the CENP-E motor domain from binding to ATP. • It preferentially inhibits proliferation of tumor cells but not non-cancerous cells. • It causes a defect in chromosome alignment, thereby inducing mitotic arrest. [ABSTRACT FROM AUTHOR]

A high-throughput RapidFire mass spectrometry assay is described for elongation of very long-chain fatty acids family 6 (Elovl6). Elovl6 is a microsomal enzyme that regulates the elongation of C12-16 saturated and monounsaturated fatty acids. Elovl6 may be a new therapeutic target for fat metabolism disorders such as obesity, type 2 diabetes, and nonalcoholic steatohepatitis. To identify new Elovl6 inhibitors, we developed a high-throughput fluorescence screening assay in 1536-well format. However, a number of false positives caused by fluorescent interference have been identified. To pick up the real active compounds among the primary hits from the fluorescence assay, we developed a RapidFire mass spectrometry assay and a conventional radioisotope assay. These assays have the advantage of detecting the main products directly without using fluorescent-labeled substrates. As a result, 276 compounds (30%) of the primary hits (921 compounds) in a fluorescence ultra-high-throughput screening method were identified as common active compounds in these two assays. It is concluded that both methods are very effective to eliminate false positives. Compared with the radioisotope method using an expensive 14 C-labeled substrate, the RapidFire mass spectrometry method using unlabeled substrates is a high-accuracy, high-throughput method. In addition, some of the hit compounds selected from the screening inhibited cellular fatty acid elongation in HEK293 cells expressing Elovl6 transiently. This result suggests that these compounds may be promising lead candidates for therapeutic drugs. Ultra-high-throughput fluorescence screening followed by a RapidFire mass spectrometry assay was a suitable strategy for lead discovery against Elovl6. [ABSTRACT FROM AUTHOR]

Highlights: [•] Novel dynamin inhibitor, which decreases actin polymerization, was identified. [•] The compound strongly reduced dynamin GTPase activity, cell migration and invasion. [•] Potent anti cancer drug targeting for dynamin is proposed. [Copyright &y& Elsevier]

Abstract: Kynurenine (Kyn), a metabolite of tryptophan (Trp), is known to be a key regulator of human immune responses including cancer immune tolerance. Therefore, abrogation of Kyn production from cancer cells by small molecules may be a promising approach to anticancer therapy. Indeed, several small molecule inhibitors of indoleamine 2,3-dioxygenase (IDO), a rate-limiting enzyme in the catabolism of Trp to Kyn, exert antitumor effects in animal models. We screened our chemical libraries using a cell-based Kyn production assay to identify a new type of small molecules that regulate Kyn production, and for the first time identified a benzenesulfonamide derivative (compound 1) as a hit with the ability to inhibit Kyn production in interferon-γ (IFN-γ)-stimulated A431 and HeLa cells. Unlike the previously identified S-benzylisothiourea derivative, compound 2, compound 1 had little effect on the enzymatic activity of recombinant human IDO in vitro but suppressed the expression of IDO at the mRNA level in cells. Furthermore, compound 1 suppressed STAT1-dependent transcriptional activity and DNA binding, whereas no decrement in either the expression or phosphorylation level of STAT1 was observed. The inhibition of IDO expression by several benzenesulfonamide derivatives is associated with the suppression of STAT1. Thus, compound 1 and its analogs might be useful for analyzing the regulation of IDO activation, and STAT1-targeting could be an alternative to the IDO-directed approach for the regulation of Kyn levels by small molecules in the tumor microenvironment. [Copyright &y& Elsevier]

Abstract: Recent studies have demonstrated that tocotrienol (T3) is superior to tocopherol (Toc) for cancer chemoprevention. However, there is little information on whether Toc influences the anticancer property of T3. In this study, we investigated the influence of Toc on the cytotoxic effects of δ-T3 in DLD-1 human colorectal adenocarcinoma cells. Toc, especially α-Toc, attenuated δ-T3-induced cytotoxicity and apoptosis in DLD-1 cells, whereas Toc alone did not exhibit any cytotoxic effect. δ-T3-induced cell cycle arrest and proapoptotic gene/protein expression (e.g., p21, p27, and caspases) were abrogated by α-Toc. Furthermore, coadministration of α-Toc decreased δ-T3 uptake into DLD-1 cells in a dose-dependent manner. These results indicate that α-Toc is not only less cytotoxic to cancer cells, but it also reduces the cytotoxicity of δ-T3 by inhibiting its cellular uptake. [Copyright &y& Elsevier]

Abstract: The protein Survivin is selectively overexpressed in a variety of cancers, but not in normal tissues. It has been reported to be involved in cell survival and cell division. However, the molecular mechanisms involved in its function are not clear, although several binding partner proteins have been proposed to date. Here, we report the identification of a novel small molecule Survivin antagonist, which disrupts the Survivin–Smac/DIABLO interaction in cells. In order to identify Survivin-directed antagonists, we developed a high-throughput screening system based on AlphaScreen technology, which allows the identification of small molecules with the ability to inhibit the interaction of Survivin with Smac/DIABLO or INCENP in vitro. We screened chemical libraries, generated in-house, using this system and identified a 5-deazaflavin analog (compound 1) as a hit compound that selectively inhibited the interaction of Survivin with Smac/DIABLO but not INCENP. In cultured cells, compound 1 abrogated the formation of the complex between Survivin and Smac/DIABLO. In addition, this compound was able to sensitize cultured cells to doxorubicin-mediated DNA damage stress and synergistically enhance apoptotic cell death. Thus, the small-molecule inhibitor described here may serve as a proof-of-principle agent for discriminating between the multiple functions of Survivin. [Copyright &y& Elsevier]

Abstract: Dynamic remodeling of actin filaments are bases for a variety of cellular events including cell motility and cancer invasion, and the regulation of actin dynamics implies dynamin, well characterized endocytotic protein. Here we report that dynasore, a inhibitor of dynamin GTPase, potently destabilizes F-actin in vitro, and it severely inhibits the formation of pseudopodia and cancer cell invasion, both of which are supported by active F-actin formation. Dynasore rapidly disrupted F-actin formed in brain cytosol in vitro, and the dynasore’s effect on F-actin was indirect. Dynasore significantly suppressed serum-induced lamellipodia formation in U2OS cell. Dynasore also destabilized F-actin in resting cells, which caused the retraction of the plasma membrane. A certain amount of dynamin 2 in U2OS cells localized along F-actin, and co-localized with cortactin, a physiological binding partner of dynamin and F-actin. However, these associations of dynamin were partially disrupted by dynasore treatment. Furthermore, invasion activity of H1080 cell, a lung cancer cell line, was suppressed by approximately 40% with dynasore treatment. These results strongly suggest that dynasore potently destabilizes F-actin, and the effect implies dynamin. Dynasore or its derivative would be suitable candidates as potent anti-cancer drugs. [Copyright &y& Elsevier]

Abstract: Constitutive activation of the oncogenic transcription factor STAT3 frequently occurs in various human malignancies. STAT3 activation involves dimerization via intermolecular pTyr–SH2 interaction. Thus, antagonizing this interaction is a feasible approach to inhibit STAT3 activation for cancer therapy. In order to identify selective STAT3 inhibitors, we developed a biochemical HTS system based on AlphaScreen technology, which measures the abilities of test compounds to antagonize pTyr–SH2 interactions. We screened our chemical libraries using this system and identified 5,15-diphenylporphyrin (5,15-DPP) as a selective STAT3–SH2 antagonist. Selective inhibition of STAT3 nuclear translocation and DNA biding activity was observed in cells treated with 5,15-DPP. IL-6-dependent dimerization of STAT3, c-myc promoter binding and c-myc protein expression were all suppressed by 5,15-DPP, whereas no decrement in either expression or phosphorylation level of STAT3 was observed. Thus, the HTS assay system represented herein may be useful for identifying novel STAT3–SH2 antagonists. [Copyright &y& Elsevier]

Telomerase is a specialized reverse transcriptase responsible for maintaining the termini of linear chromosomes. The human enzyme is a ribonucleoprotein complex minimally comprising a catalytic protein moiety (hTERT) and an RNA subunit (hTR) which acts as the template for the reverse transcriptase reaction. Here we report expression of recombinant hTERT protein in insect cells utilizing a baculovirus expression system. The recombinant hTERT protein reconstitutes telomerase activity in the presence of hTR, either when co-expressed in insect cells or when added in vitro. Reconstitution of telomerase activity using this system will facilitate further analysis of the biochemical and biophysical properties of this enzyme. [Copyright &y& Elsevier]