The functional and therapeutic importance of the Warburg effect is increasingly recognized, and glycolysis has become a target of anticancer strategies. We recently reported the identification of a group of novel small compounds that inhibit basal glucose transport and reduce cancer cell growth by a glucose deprivation-like mechanism. We hypothesized that the compounds target Glut1 and are efficacious in vivo as anticancer agents. Here, we report that a novel representative compound WZB117 not only inhibited cell growth in cancer cell lines but also inhibited cancer growth in a nude mouse model. Daily intraperitoneal injection of WZB117 at 10 mg/kg resulted in a more than 70% reduction in the size of human lung cancer of A549 cell origin. Mechanism studies showed that WZB117 inhibited glucose transport in human red blood cells (RBC), which express Glut1 as their sole glucose transporter. Cancer cell treatment with WZB117 led to decreases in levels of Glut1 protein, intracellular ATP, and glycolytic enzymes. All these changes were followed by increase in ATPsensing enzyme AMP-activated protein kinase (AMPK) and declines in cyclin E2 as well as phosphorylated retinoblastoma, resulting in cell-cycle arrest, senescence, and necrosis. Addition of extracellular ATP rescued compound-treated cancer cells, suggesting that the reduction of intracellular ATP plays an important role in the anticancer mechanism of the molecule. Senescence induction and the essential role of ATP were reported for the first time in Glut1 inhibitor-treated cancer cells. Thus, WZB117 is a prototype for further development of anticancer therapeutics targeting Glut1-mediated glucose transport and glucose metabolism.

Ribosomal frameshifting, a translational mechanism used during retroviral replication, involves a directed change in reading frame at a specific site at a defined frequency. Such programmed frameshifting at the mouse mammary tumor virus (MMTV) gag‐pro shift site requires two mRNA signals: a heptanucleotide shifty sequence and a pseudoknot structure positioned downstream. Using in vitro translation assays and enzymatic and chemical probes for RNA structure, we have defined features of the pseudoknot that promote efficient frameshifting. Heterologous RNA structures, e.g. a hairpin, a tRNA or a synthetic pseudoknot, substituted downstream of the shifty site fail to promote frameshifting, suggesting that specific features of the MMTV pseudoknot are important for function. Site‐directed mutations of the MMTV pseudoknot indicate that the pseudoknot junction, including an unpaired adenine nucleotide between the two stems, provides a specific structural determinant for efficient frameshifting. Pseudoknots derived from other retroviruses (i.e. the feline immunodeficiency virus and the simian retrovirus type 1) also promote frameshifting at the MMTV gag‐pro shift site, dependent on the same structure at the junction of the two stems.

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The T box transcription antitermination system is a riboswitch found primarily in Gram-positive bacteria which monitors the aminoacylation of the cognate tRNA and regulates a variety of amino acid-related genes. Novel 4,5-disubstituted oxazolidinones were identified as high affinity RNA molecular effectors that modulate the transcription antitermination function of the T box riboswitch.Identifying RNA ligands that modulate transcription regulation is an important area for drug discovery that has been only minimally explored to date. One potential therapeutic target is the T box transcription antitermination mechanism. This mechanism regulates many amino acid-related genes, including aminoacyl-tRNA synthetase genes, and is found predominantly in Gram-positive bacteria. 1 The T box RNAs are members of the "riboswitch" family in which nascent RNAs directly sense effector molecules to control gene expression. 2-4 The T box genes contain a complex set of structural elements within the 5′ untranslated region of their mRNAs (the "leader region"). These elements include a transcription termination signal that abrogates synthesis of the full-length mRNA and a competing antiterminator element. Readthrough of the terminator, and expression of the downstream gene, is dependent on binding of a specific uncharged tRNA to the nascent RNA transcript; each gene in the T box family responds independently to the cognate uncharged tRNA. 5 The T box antitermination mechanism can function in the absence of additional cellular factors, 6 and the antiterminator RNA element is a critical component of the mechanism. 5 The leader RNA-tRNA interaction stabilizes the antiterminator element, thereby preventing formation of the competing terminator element (Figure 1). The antiterminator element is highly conserved and has been extensively characterized by genetic, biochemical and structural biology approaches. 7-9 A significant challenge in rational ligand design for RNA structure-specific binding is to achieve both high affinity and excellent tertiary structure specificity. Aminoglycosides, the most widely studied RNA ligands, bind primarily in divalent cation binding sites. 10-12 The electrostatic attraction between the multiple protonated amino groups and the negatively charged RNA phosphate backbone leads to very high affinities. However, due to the ubiquitous presence of divalent cation binding sites in RNA, primarily for tertiary fold stabilization, 13 the aminoglycosides readily bind many RNAs 14 thus reducing their utility for RNA structurespecific ligand design. A variety of other RNA ligands have been investigated, 15-21 but few Correspondence to: Jennifer V. Hines. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the produ...