Chemical genetics identify eIF2α kinase heme-regulated inhibitor as an anticancer target.

Translation initiation plays a critical role in cellular homeostasis, proliferation, differentiation and malignant transformation. Consistently, increasing the abundance of the eIF2-GTP-tRNA(i)(Met) translation initiation complex transforms normal cells and contributes to cancer initiation and the severity of some anemias. The chemical modifiers of the eIF2-GTP-tRNA(i)(Met) ternary complex are therefore invaluable tools for studying its role in the pathobiology of human disorders and for determining whether this complex can be pharmacologically targeted for therapeutic purposes. Using a cell-based assay, we identified N,N'-diarylureas as unique inhibitors of ternary complex accumulation. Direct functional-genetic and biochemical evidence demonstrated that the N,N'-diarylureas activate heme-regulated inhibitor kinase, thereby phosphorylating eIF2α and reducing the abundance of the ternary complex. Using tumor cell proliferation in vitro and tumor growth in vivo as paradigms, we demonstrate that N,N'-diarylureas are potent and specific tools for studying the role of eIF2-GTP-tRNA(i)(Met) ternary complex in the pathobiology of human disorders.

The role of plasminogen activator inhibitor-1 polymorphism, factor-V-Leiden, and prothrombin-20210 mutations in pulmonary thromboembolism.

Polymorphism in plasminogen activator inhibitor-1 gene is suggested to be associated with an increased risk of venous thromboembolism. The aim of this study was to investigate the association of plasminogen activator inhibitor-1 gene polymorphism and its coexistence with factor-V-Leiden and prothrombin-20210 mutations in pulmonary thromboembolism. The authors investigated plasminogen activator inhibitor-1 4G/5G polymorphism, factor-V-Leiden, and prothrombin-20210 mutations in 143 pulmonary thromboembolism patients and 181 controls. Plasminogen activator inhibitor-1 4G/4G, 4G/5G, and 5G/5G gene polymorphisms and prothrombin-20210 mutations were not different between cases and controls. Factor-V-Leiden mutation was present in 21.0% and 7.7% of the cases and controls, respectively, P = .001. Neither different plasminogen activator inhibitor-1 genotypes and 4G allele nor coexistence of the allele with factor-V-Leiden or prothrombin-20210 was associated with the risk of recurrence. As a result, plasminogen activator inhibitor-1 gene polymorphism or its concomitant presence with mentioned mutations was not found to be associated with increased risk for pulmonary thromboembolism or recurrent disease in this study.

MENA is a transcriptional target of the Wnt/beta-catenin pathway.

Wnt/ß-catenin signalling pathway plays important roles in embryonic development and carcinogenesis. Overactivation of the pathway is one of the most common driving forces in major cancers such as colorectal and breast cancers. The downstream effectors of the pathway and its regulation of carcinogenesis and metastasis are still not very well understood. In this study, which was based on two genome-wide transcriptomics screens, we identify MENA (ENAH, Mammalian enabled homologue) as a novel transcriptional target of the Wnt/ß-catenin signalling pathway. We show that the expression of MENA is upregulated upon overexpression of degradation-resistant ß-catenin. Promoters of all mammalian MENA homologues contain putative binding sites for Tcf4 transcription factor--the primary effector of the Wnt/ß-catenin pathway and we demonstrate functionality of these Tcf4-binding sites using luciferase reporter assays and overexpression of ß-catenin, Tcf4 and dominant-negative Tcf4. In addition, lithium chloride-mediated inhibition of GSK3ß also resulted in increase in MENA mRNA levels. Chromatin immunoprecipitation showed direct interaction between ß-catenin and MENA promoter in Huh7 and HEK293 cells and also in mouse brain and liver tissues. Moreover, overexpression of Wnt1 and Wnt3a ligands increased MENA mRNA levels. Additionally, knock-down of MENA ortholog in D. melanogaster eyeful and sensitized eye cancer fly models resulted in increased tumor and metastasis formations. In summary, our study identifies MENA as novel nexus for the Wnt/ß-catenin and the Notch signalling cascades.