m6 A demethylase ALKBH5 promotes proliferation of esophageal squamous cell carcinoma associated with poor prognosis.

Esophageal squamous cell carcinoma (ESCC) is one of the most fatal types of malignant tumors worldwide. Epitranscriptome, such as N6 -methyladenosine (m6 A) of mRNA, is an abundant post-transcriptional mRNA modification and has been recently implicated to play roles in several cancers, whereas the significance of m6 A modifications is virtually unknown in ESCC. Analysis of tissue microarray of the tumors in 177 ESCC patients showed that higher expression of m6 A demethylase ALKBH5 correlated with poor prognosis and that ALKBH5 was an independent prognostic factor of the survival of patients. There was no correlation between the other demethylase FTO and prognosis. siRNA knockdown of ALKBH5 but not FTO significantly suppressed proliferation and migration of human ESCC cells. ALKBH5 knockdown delayed progression of cell cycle and accumulated the cells to G0/G1 phase. Mechanistically, expression of CDKN1A (p21) was significantly up-regulated in ALKBH5-depleted cells, and m6 A modification and stability of CDKN1A mRNA were increased by ALKBH5 knockdown. Furthermore, depletion of ALKBH5 substantially suppressed tumor growth of ESCC cells subcutaneously transplanted in BALB/c nude mice. Collectively, we identify ALKBH5 as the first m6 A demethylase that accelerates cell cycle progression and promotes cell proliferation of ESCC cells, which is associated with poor prognosis of ESCC patients.

Genome-Scale CRISPR/Cas9 Screening Reveals Squalene Epoxidase as a Susceptibility Factor for Cytotoxicity of Malformin†A1.

Malformin A1 (MA1) is a fungus-produced cyclic pentapeptide. MA1 exhibits teratogenicity to plants, fibrinolysis-enhancing activity, and cytotoxicity to mammalian cells. To clarify the cytotoxic mechanism of MA1, we screened for the genes involved in the cytotoxicity of MA1 in monocytoid U937 cells by using a CRISPR/Cas9-based genome-wide knockout library. Screening was performed by positive selection for cells that were resistant to MA1 treatment, and single guide RNAs (sgRNAs) integrated into MA1-resistant cells were analyzed by high-throughput sequencing. As a result of the evaluation of sgRNAs that were enriched in MA1-resistant cells, SQLE, which encodes squalene epoxidase, was identified as a candidate gene. SQLE-depleted U937 cells were viable in the presence of MA1, and squalene epoxidase inhibitor conferred MA1 resistance to wild-type cells. These results indicate that squalene epoxidase is implicated in the cytotoxicity of MA1. This finding represents a new insight into applications of MA1 for treating ischemic diseases.

Structure-activity relationship of cyclic pentapeptide malformins as fibrinolysis enhancers.

The formation of blood clots in blood vessels causes severe ischemic diseases such as cerebral infarction and myocardial infarction. While searching for microbial products that increase fibrinolytic activity using an in vitro fibrin degradation assay, we found malformin A1, a disulfide form of cyclo(-d-Cys-d-Cys-l-Val-d-Leu-l-Ile-), as an active compound. In this study, we synthesized malformin derivatives using a solid-phase peptide synthesis method and evaluated their fibrinolytic activity and cytotoxicity. Reduction of the disulfide bond and linearization of the cyclic peptide frame decreased the pro-fibrinolytic activity. Substitution of a branched-chain amino acid with lysine resulted in loss of activity. However, protection of the amino group in the lysine derivatives by the tert-butoxycarbonyl (Boc) group rescued the inactivity. Furthermore, the phenylalanine derivatives also exhibited a similar pro-fibrinolytic effect compared to malformin A1. These results suggest that the disulfide bond, the cyclic peptide frame, and the bulky hydrophobic side chains play a crucial role in the pro-fibrinolytic activity of malformin. The effective dose of the active derivatives for the in vitro fibrin degradation showed similar ranges (1-5µM), while the order of cytotoxic potency for the active derivatives was as follows: Phe-derivatives>BocLys-derivatives>malformin A1>reduced form. These results showed no correlation between pro-fibrinolytic activity and cytotoxicity, suggesting the possibility of the synthesis for non-toxic malformin derivatives possessing the activity.

Cadmium-coordinated supramolecule suppresses tumor growth of T-cell leukemia in mice.

Cadmium is a toxic pollutant with occupational and environmental significance, due to its diverse toxic effects. Supramolecules that conjugate and decontaminate toxic metals have potential for use in treatment of cadmium intoxication. In addition, metal-coordinating ability has been postulated to contribute to the cytotoxic effects of anti-tumor agents such as cisplatin or bleomycin. Thiacalixarenes, cyclic oligomers of p-alkylphenol bridged by sulfur atoms, are supramolecules known to have potent coordinating ability to metal ions. In this study, we show that cadmium-coordinated thiacalix[4]arene tetrasulfate (TC4ATS-Cd) exhibits an anti-proliferative effect against T-cell leukemia cells. Cadmium exhibited cytotoxicity with IC50 values ranging from 36 to 129 µM against epithelia-derived cancer cell lines, while TC4ATS-Cd elicited no significant cytotoxicity (IC50 > 947 µM). However, a number of T-cell leukemia cell lines exhibited marked sensitivity to TC4ATS-Cd. In Jurkat cells, toxicity of TC4ATS-Cd occurred with an IC50 of 6.9 µM, which is comparable to that of 6.5 µM observed for cadmium alone. TC4ATS-Cd induced apoptotic cell death through activation of caspase-3 in Jurkat cells. In a xenograft model, TC4ATS-Cd (13 mg/kg) treatment significantly suppressed the tumor growth of Jurkat cells in mice. In addition, TC4ATS-Cd-treated mice exhibited significantly less cadmium accumulation in liver and kidney compared to equimolar cadmium-treated mice. These results suggest that cadmium-coordinated supramolecules may have therapeutic potential for treatment of T-cell leukemia.

Generation of intracellular single-chain antibodies directed against polypeptide GalNAc-transferase using a yeast two-hybrid system.

Mucin-type O-glycosylation is initiated by a large number of UDP-GalNAc: polypeptide N-acetylgalactosaminyltransferases (GalNAc-T). Although extensive in vitro studies using synthetic peptides as substrates suggest that most GalNAc-Ts exhibit overlapping substrate specificities, many studies have shown that individual GalNAc-Ts play an important role in both animals and humans. Further investigations of the functions of individual GalNAc-Ts including in vivo substrate proteins and O-glycosylation sites are necessary. In this study, we attempted to generate single-chain variable fragment (scFv) antibodies to bind to GalNAc-T1, T2, T3, and T4 using a yeast two-hybrid system for screening a naive chicken scFv library. Several different scFvs were isolated against a single target GalNAc-T isoform specifically under expressed in yeast and were confirmed to be expressed in mammalian cells and to retain binding activity inside the cells. Generation of these specific antibodies provides an opportunity to modify and exploit antibodies for specific applications in investigations of GalNAc-T functions.

Anti-melanogenesis effect of Glechoma hederacea L. extract on B16 murine melanoma cells.

Glechoma hederacea L. (Labiatae) has been used in folk medicine to treat various ailments for centuries. We investigated the effects of G. hederacea extract on melanogenesis in B16 melanoma cells. It significantly reduced both the cellular melanin content and tyrosinase activity in a concentration-dependent manner. An MTT assay did not reveal any obvious cytotoxicity. Furthermore, we found that G. hederacea extract decreased tyrosinase and microphthalmia-associated transcription factor protein expression, but did not inhibit tyrosinase-related protein-1 and tyrosinase-related protein-2 expression. RT-PCR analysis indicated that the antimelanogenic effect of G. hederacea extract might be due to inhibition of tyrosinase gene transcription. Moreover, this effect is regulated via suppression of microphthalmia-associated transcription factor protein expression. Our data indicate that G. hederacea extract inhibits melanin synthesis in B16 melanoma cells but is not cytotoxic. Hence it might prove a useful therapeutic agent for treating hyperpigmentation and an effective component of whitening cosmetics.

In vitro prominent bone regeneration by release zinc ion from Zn-modified implant.

Zinc is one of the trace elements which induce the proliferation and the differentiation of the osteoblast. In the previous study, we found that zinc ions (Zn(2+) ion)-releasing titanium implants had excellent bone fixation using a rabbit femurs model. In this study, we isolated the Zn(2+) ions (eluted Zn(2+) ion; EZ) released from the implant surface, and evaluated the effect of EZ on the osteogenesis of human bone marrow-derived mesenchymal cells (hBMCs). In the result, it was found that the EZ stimulated cell viability, osteoblast marker gene (type I collagen, osteocalcin (OC), alkaline phosphatase (ALP) and bone sialoprotein (BSP)) expressions and calcium deposition in hBMCs.

Fibrinolytic activation promoted by the cyclopentapeptide malformin: involvement of cytoskeletal reorganization.

Malformin A1, a cyclopentapeptide of fungal origin, enhances cellular fibrinolytic activity depending on the existence of a cofactor in blood plasma. However, the nature of this cofactor remains unknown. Here, we report that vitronectin acts as a plasma cofactor of malformin A1. We purified the cofactor from bovine plasma by activity-based fractionation, and confirmed that vitronectin in conjunction with plasminogen supports the activity of malformin A1 to promote the fibrinolytic activity of U937 cells. Malformin A1 action was abolished by Arg-Gly-Asp peptide (a competitor of vitronectin-integrin binding), wortmannin (an inhibitor of signaling kinases), and cytochalasin B (an inhibitor of actin polymerization). Changes in actin organization and a decrease in filopodia were observed in cells treated with malformin A1 and plasma. A focal localization of plasminogen on the cell surface was augmented by malformin A1, whereas the amount of cell-surface-bound plasminogen was minimally altered by the treatment. Our results suggest the involvement of cytoskeletal reorganization via vitronectin signaling in the cellular fibrinolytic activity-enhancing action of malformin A1.

Niemann-Pick C1 protein transports copper to the secretory compartment from late endosomes where ATP7B resides.

Wilson disease is a genetic disorder characterized by the accumulation of copper in the body by defective biliary copper excretion. Wilson disease gene product (ATP7B) functions in copper incorporation to ceruloplasmin (Cp) and biliary copper excretion. However, copper metabolism in hepatocytes has been still unclear. Niemann-Pick disease type C (NPC) is a lipid storage disorder and the most commonly mutated gene is NPC1 and its gene product NPC1 is a late endosome protein and regulates intracellular vesicle traffic. In the present study, we induced NPC phenotype and examined the localization of ATP7B and secretion of holo-Cp, a copper-binding mature form of Cp. The vesicle traffic was modulated using U18666A, which induces NPC phenotype, and knock down of NPC1 by RNA interference. ATP7B colocalized with the late endosome markers, but not with the trans-Golgi network markers. U18666A and NPC1 knock down decreased holo-Cp secretion to culture medium, but did not affect the secretion of other secretory proteins. Copper accumulated in the cells after the treatment with U18666A. These findings suggest that ATP7B localizes in the late endosomes and that copper in the late endosomes is transported to the secretory compartment via NPC1-dependent pathway and incorporated into apo-Cp to form holo-Cp.

Simaomicin α, a polycyclic xanthone, induces G1 arrest with suppression of retinoblastoma protein phosphorylation.

Recent progress in cancer biology research has shown that abnormal proliferation in tumor cells can be attributed to aberrations in cell cycle regulation, especially in G1 phase. During the course of searching for microbial metabolites that affect cell cycle distribution, we have found that simaomicin α, a polycyclic xanthone antibiotic, arrests the cell cycle at G1 phase. Treatment of T-cell leukemia Jurkat cells with 3 nM simaomicin α induced an increase in the number of cells in G1 and a decrease in those in G2­M phase. Cell cycle aberrations induced by simaomicin α were also detected in colon adenocarcinoma HCT15 cells. Simaomicin α had antiproliferative activities in various tumor cell lines with 50% inhibitory concentration values in the range of 0.3­19 nM. Furthermore, simaomicin α induced an increase in cellular caspase-3 activity and DNA fragmentation, indicating that simaomicin α promotes apoptosis. The retinoblastoma protein phosphorylation status of simaomicin α-treated cell lysate was lower than that of control cells, suggesting that the target molecule of simaomicin α is in a pathway upstream of retinoblastoma protein phosphorylation. In the course of evaluating polycyclic xanthone antibiotics structurally related to simaomicin α, we also found that cervinomycin A1 stimulated accumulation of treated cells in G1 phase. These results indicate that the polycyclic xanthones, including simaomicin α and cervinomycin A1, may be candidate cancer chemotherapeutic agents.

Expression and localization of regenerating gene I in a rat liver regeneration model.

Regenerating gene (Reg) I has been identified as a regenerative/proliferative factor for pancreatic islet cells. We examined Reg I expression in the regenerating liver of a rat model that had been administered 2-acetylaminofluorene and treated with 70% partial hepatectomy (2-AAF/PH model), where hepatocyte and cholangiocyte proliferation was suppressed and the hepatic stem cells and/or hepatic progenitor cells were activated. In a detailed time course study of activation of hepatic stem cells in the 2-AAF/PH model, utilizing immunofluorescence staining with antibodies of Reg I and other cell-type-specific markers, we found that Reg I-expressing cells are present in the bile ductules and increased during regeneration. Reg I-expressing cells were colocalized with CK19, OV6, and AFP. These results demonstrate that Reg I is significantly upregulated in the liver of the 2-AAF/PH rat model, accompanied by the formation of bile ductules during liver regeneration.

Lys17 in the 'lasso' peptide lariatin A is responsible for anti-mycobacterial activity.

C-terminal-lacking fragments of the anti-mycobacterial peptide lariatin A were obtained by hydrolysis using carboxypeptidase P and their anti-mycobacterial activities were evaluated. Lys17 was found to be essential for their antimicrobial activity. A molecular dynamics simulation, with explicit water molecules, helped determine the structural characteristics of Lys17 of lariatin A. The simulation revealed the dynamic formation and deformation of a salt bridge between the N(xi) atom of Lys17 and the carboxyl group of C-terminal Pro18, which is deemed to be crucial for the compound's anti-mycobacterial activity.

A highly sensitive probe detecting low pH area of HeLa cells based on rhodamine B modified beta-cyclodextrins.

Two kinds of rhodamine modified beta-cyclodextrins (R-1 and R-2), which are coupled up ethylene diamine (EDA) and tetraethylene pentamine (TEPA) between Rh B and beta-cyclodextrin, respectively, have been synthesized. R-1 and 2 work as a new fluorogenic probe for monitoring pH of Hela cells, and MTT of assay R-1, R-2, and rhodamine B indicate that less a cytotoxicity of those R-1 and R-2 than that of rhodamine B, where R-1 has much less one than that of R-2. The fluorogenetic probe capability of R-2 was recognized in an area of acidic area in living cell, which is lysosome.

REG I enhances chemo- and radiosensitivity in squamous cell esophageal cancer cells.

Identification of reliable markers of chemo- and radiosensitivity and the key molecules that enhance the susceptibility of squamous esophageal cancer cells to anticancer treatments would be highly desirable. To test whether regenerating gene (REG) I expression enhances chemo- and radiosensitivity in esophageal squamous cell carcinoma cells, we used MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays to compare the chemo- and radiosensitivities of untransfected TE-5 and TE-9 cells with those of cells stably transfected with REG Ialpha and Ibeta. We then used flow cytometry to determine whether REG I expression alters cell cycle progression. No REG I mRNA or protein were detected in untransfected TE-5 and TE-9 cells. Transfection with REG Ialpha and Ibeta led to strong expression of both REG I mRNA and protein in TE-5 and TE-9 cells, which in turn led to significant increases in both chemo- and radiosensitivity. Cell cycle progression was unaffected by REG I expression. REG I thus appears to enhance the chemo- and radiosensitivity of squamous esophageal cancer cells, which suggests that it may be a useful target for improved and more individualized treatments for patients with esophageal squamous cell carcinoma.

REG Ialpha is a reliable marker of chemoradiosensitivity in squamous cell esophageal cancer patients.

BACKGROUND: A reliable marker of chemoradiosensitivity that would enable appropriate and individualized treatment of thoracic squamous cell esophageal cancer has long been sought. We investigated whether regenerating gene (REG) Ialpha is such a marker. METHODS: We assessed expression of REG Ialpha in untreated endoscopic biopsy specimens and examined the correlation between REG Ialpha expression and the clinical responses to definitive chemoradiotherapy and prognosis. We also examined the relationship between REG Ialpha expression in the resected tumor and the prognosis of patients who received esophagectomy for thoracic squamous cell esophageal cancer. RESULTS: Among the 42 patients treated with definitive chemoradiotherapy, 8 of the 23 REG I-positive patients (35%) showed complete responses to chemoradiotherapy, while only one of the 19 REG I-negative patients did so. The survival rate among the REG I-positive patients was significantly better than among the REG I-negative patients. For the 76 patients treated surgically, there was no significant difference in the survival rates among the REG I-positive and REG I-negative patients. CONCLUSIONS: REG Ialpha expression in squamous cell esophageal carcinoma may be a reliable marker of chemoradiosensitivity. We anticipate that it will enable us to provide more appropriate and individualized treatment to patients of advanced esophageal squamous cell carcinoma.

Acute effects on the lung and the liver of oral administration of cerium chloride on adult, neonatal and fetal mice.

We evaluated tissue changes associated with cerium chloride administration via gavage to adult mice, via milk to neonatal mice and transplacentally to fetal mice. Change in adults consisted of extensive pulmonary hemorrhage, pulmonary venous congestion, thickened alveolar septae, hepatic necrosis and neutrophil infiltrations. Those in fetal mice consisted of pulmonary and hepatic congestion. These results indicate that gavage cerium administration elicited subtle tissue changes, though oral toxicity is rather low. These changes were less severe in neonatal and fetal mice. When cerium was injected into adult mice through the tail vein, cerium was distributed mainly to the liver, spleen and lung dose-dependently with the cerium concentration gradually decreasing after 3 days. A study of cerium anticoagulation in mouse plasma showed that clotting time was significantly prolonged when cerium was added to plasma. These results suggest that cerium may disturb blood coagulation and cause pulmonary and hepatic vascular congestion.

Involvement of RSK1 activation in malformin-enhanced cellular fibrinolytic activity.

Pharmacological interventions to enhance fibrinolysis are effective for treating thrombotic disorders. Utilizing the in vitro U937 cell line-based fibrin degradation assay, we had previously found a cyclic pentapeptide malformin A1 (MA1) as a novel activating compound for cellular fibrinolytic activity. The mechanism by which MA1 enhances cellular fibrinolytic activity remains unknown. In the present study, we show that RSK1 is a crucial mediator of MA1-induced cellular fibrinolysis. Treatment with rhodamine-conjugated MA1 showed that MA1 localizes mainly in the cytoplasm of U937 cells. Screening with an antibody macroarray revealed that MA1 induces the phosphorylation of RSK1 at Ser380 in U937 cells. SL0101, an inhibitor of RSK, inhibited MA1-induced fibrinolytic activity, and CRISPR/Cas9-mediated knockout of RSK1 but not RSK2 suppressed MA1-enhanced fibrinolysis in U937 cells. Synthetic active MA1 derivatives also induced the phosphorylation of RSK1. Furthermore, MA1 treatment stimulated phosphorylation of ERK1/2 and MEK1/2. PD98059, an inhibitor of MEK1/2, inhibited MA1-induced phosphorylation of RSK1 and ERK1/2, indicating that MA1 induces the activation of the MEK-ERK-RSK pathway. Moreover, MA1 upregulated the expression of urokinase-type plasminogen activator (uPA) and increased uPA secretion. These inductions were abrogated in RSK1 knockout cells. These results indicate that RSK1 is a key regulator of MA1-induced extracellular fibrinolytic activity.

The CCR4-NOT deadenylase complex controls Atg7-dependent cell death and heart function.

Shortening and removal of the polyadenylate [poly(A)] tail of mRNA, a process called deadenylation, is a key step in mRNA decay that is mediated through the CCR4-NOT (carbon catabolite repression 4-negative on TATA-less) complex. In our investigation of the regulation of mRNA deadenylation in the heart, we found that this complex was required to prevent cell death. Conditional deletion of the CCR4-NOT complex components Cnot1 or Cnot3 resulted in the formation of autophagic vacuoles and cardiomyocyte death, leading to lethal heart failure accompanied by long QT intervals. Cnot3 bound to and shortened the poly(A) tail of the mRNA encoding the key autophagy regulator Atg7. In Cnot3-depleted hearts, Atg7 expression was posttranscriptionally increased. Genetic ablation of Atg7, but not Atg5, increased survival and partially restored cardiac function of Cnot1 or Cnot3 knockout mice. We further showed that in Cnot3-depleted hearts, Atg7 interacted with p53 and modulated p53 activity to induce the expression of genes encoding cell death-promoting factors in cardiomyocytes, indicating that defects in deadenylation in the heart aberrantly activated Atg7 and p53 to promote cell death. Thus, mRNA deadenylation mediated by the CCR4-NOT complex is crucial to prevent Atg7-induced cell death and heart failure, suggesting a role for mRNA deadenylation in targeting autophagy genes to maintain normal cardiac homeostasis.

Purification and characterization of dipeptidase hydrolyzing L-cysteinylglycine from radish cotyledon.

Dipeptidase activity was detected in the soluble fraction of radish (Raphanus sativus L.) cotyledon, and the purified enzyme had a specific activity of 7.32 nkat/mg protein for hydrolyzing L-cysteinylglycine. The dipeptidase was found to be a hexameric metalloenzyme, composed of homological 55 kDa-subunits. This is the first glutathione catabolism-related dipeptidase isolated from higher plants.

Oxaline, a fungal alkaloid, arrests the cell cycle in M phase by inhibition of tubulin polymerization.

Oxaline and neoxaline, fungal alkaloids, were found to inhibit cell proliferation and to induce cell cycle arrest at the G(2)/M phase in Jurkat cells. CBP501 (a peptide corresponding to amino acids 211-221 of Cdc25C phosphatase), which inhibits the G(2) checkpoint, did not affect the G(2)/M arrest caused by oxaline, suggesting that oxaline causes M phase arrest but not G(2) phase arrest. The Cdc2 phosphorylation level of oxaline-treated cell lysate was lower than that of the control cells, indicating that oxaline arrests the M phase. Oxaline disrupted cytoplasmic microtubule assembly in 3T3 cells. Furthermore, oxaline inhibited polymerization of microtubule protein and purified tubulin dose-dependently in vitro. In a binding competition assay, oxaline inhibited the binding of [(3)H]colchicine to tubulin, but not that of [(3)H]vinblastine. These results indicate that oxaline inhibits tubulin polymerization, resulting in cell cycle arrest at the M phase.