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The rapid proliferation of myeloid leukemia cells is highly dependent on increased glucose metabolism. Through an unbiased metabolomics analysis of leukemia cells, we found that the glycogenic precursor UDP-D-glucose is pervasively upregulated, despite low glycogen levels. Targeting the rate-limiting glycogen synthase 1 (GYS1) not only decreased glycolytic flux but also increased activation of the glycogen-responsive AMP kinase (AMPK), leading to significant growth suppression. Further, genetic and pharmacological hyper-activation of AMPK was sufficient to induce the changes observed with GYS1 targeting. Cancer genomics data also indicate that elevated levels of the glycogenic enzymes GYS1/2 or GBE1 (glycogen branching enzyme 1) are associated with poor survival in AML. These results suggest a novel mechanism whereby leukemic cells sustain aberrant proliferation by suppressing excess AMPK activity through elevated glycogenic flux and provide a therapeutic entry point for targeting leukemia cell metabolism. [ABSTRACT FROM AUTHOR]

Phosphatidylinositide 3-kinases (PI3Ks) are intracellular signal transducer enzymes that recruit protein kinase B (aka Akt) to the cell membrane, the subsequent activation of which regulates many cellular functions. PI3K/Akt activity is up-regulated within mesocorticolimbic structures in animal models of alcoholism, but less is known regarding PI3K/Akt activity in animal models of cocaine addiction. Given that prefrontal cortex (PFC) is grossly dysregulated in addiction, we studied how cocaine affects protein indices of PFC PI3K/Akt activity in rat and mouse models and examined the relevance of PI3K activity for cocaine-related learning. Immunoblotting of mouse medial PFC at 3 weeks withdrawal from a cocaine-sensitization regimen (seven injections of 30 mg/kg, intraperitoneal [IP]) revealed increased kinase activity, as did immunoblotting of tissue from the ventral PFC of rats with a history of long-access intravenous cocaine self-administration (0.25 mg/0.1 mL infusion; 10 days of 6 h/d cocaine access). Interestingly, increased Akt phosphorylation was observed in rat ventromedial PFC at both 3- and 30-day withdrawal only in animals re-exposed to cocaine-associated cues. A conditioned place-preference paradigm in mice and a cue-elicited drug-seeking test in rats were conducted to determine the functional relevance for elevated PI3K activity for addiction-related behavior. In both cases, an intra-PFC infusion of the PI3K inhibitor wortmannin (50μM) reduced drug-seeking behavior. Taken together, this cross-species, interdisciplinary, study provides convincing evidence that cocaine history produces an enduring increase in PI3K/Akt-dependent signaling within the more ventral aspect of the PFC that is relevant to behavioral reactivity to drug-associated cues/contexts. As such, PI3K inhibitors may well serve as an effective strategy for reducing drug cue reactivity and craving in cocaine addiction. [ABSTRACT FROM AUTHOR]

Chlamydia is an obligate intracellular bacterium that relies on host cells for essential nutrients and adenosine triphosphate (ATP) for a productive infection. Although the unfolded protein response (UPR) plays a major role in certain microbial infectivity, its role in chlamydial pathogenesis is unknown. We hypothesized that Chlamydia induces UPR and exploits it to upregulate host cell uptake and metabolism of glucose, production of ATP, phospholipids, and other molecules required for its replicative development and host survival. Using a combination of biochemical and pathway inhibition assays, we showed that the 3 UPR pathway transducers-protein kinase RNA-activated (PKR)-like ER kinase (PERK), inositol-requiring enzyme-1α (IRE1α), and activating transcription factor-6α (ATF6α)-were activated during Chlamydia infection. The kinase activity of PERK and ribonuclease (RNase) of IRE1α mediated the upregulation of hexokinase II and production of ATP via substrate-level phosphorylation. In addition, the activation of PERK and IRE1α promoted autophagy formation and apoptosis resistance for host survival. Moreover, the activation of IRE1α resulted in the generation of spliced X-box binding protein 1 (sXBP1) and upregulation of lipid production. The vital role of UPR pathways in Chlamydia development and pathogenesis could lead to the identification of potential molecular targets for therapeutics against Chlamydia. [ABSTRACT FROM AUTHOR]

Transforming growth factor-β1 (TGF-β1) promotes tumor metastasis by inducing an epithelial-to-mesenchymal transition (EMT) in cancer cells. In this study, we investigated the effects of BIX02189 and XMD8-92, pharmacologic inhibitors of the MEK5 [mitogen-activated protein kinase/extracellular-signal-regulated kinase (ERK)5] signaling pathway, on the EMT and migration of cancer cells induced by TGF-β1. In human A549 lung cancer cells, TGF-β1-induced EMT, cell motility, and expression of matrix metalloproteinase-2 were completely inhibited by BIX02189, but not by XMD8-92 or small interference RNAs specific to MEK5 and ERK5. Interestingly, BIX02189 strongly blocked the activation of TGF-β1 signaling components, and this inhibitory effect was not reproduced by MEK5 inhibition. Molecular docking simulation and kinase assays revealed that BIX02189 binds directly to the ATP-binding site of the TGF-β receptor type I (TβRI) and suppresses its kinase activity. Finally, the anti-metastatic effect of BIX02189 was validated in a TβRI-derived A549 xenograft mouse model. Collectively, these findings newly characterize BIX02189 as a potent inhibitor of TβRI that can block the tumor metastatic activity of TGF-β1. [ABSTRACT FROM AUTHOR]

Insulin-like growth factor I receptor (IGF1R) is frequently upregulated in breast cancer. Due to its intrinsic tyrosine kinase activity, aberrant activation of the IGF1R signaling axis may enhance tumor cell proliferation and cancer stemness, causing tumor relapse, metastasis and resistance to chemotherapy. We utilized a chromatin RNA in situ reverse transcription (CRIST) approach to characterize molecular factors that regulate the IGF1R network. We identified lncRNA HULC (Highly Upregulated in Liver Cancer) as a key trans-regulator of IGF1R in breast cancer cells. Loss of HULC suppressed the expression of IGF1R and the activation of its downstream PI3K/AKT pathway, while HULC overexpression activated the axis in breast cancer cells. Using a transcription-associated trap (RAT) assay, we demonstrated that HULC functioned as a nuclear lncRNA and epigenetically activated IGF1R by directly binding to the intragenic regulatory elements of the gene, orchestrating intrachromosomal interactions, and promoting histone H3K9 acetylation. The activated HULC-IGF1R/PI3K/AKT pathway mediated tumor resistance to cisplatin through the increased expression of cancer stemness markers, including NANOG, SOX2, OCT4, CD44 and ALDH1A1. In immunodeficient mice, stimulation of the HULC-IGF1R pathway promoted tumor metastasis. These data suggest that HULC may be a new epigenetic target for IGF1R axis-targeted therapeutic intervention. [ABSTRACT FROM AUTHOR]