Browsing by Author "Jiang, Jie"

Now showing 1 - 7 of 7
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    Asparagine bioavailability regulates the translation of MYC oncogene
    (Springer Nature, 2022) Srivastava, Sankalp; Jiang, Jie; Misra, Jagannath; Seim, Gretchen; Staschke, Kirk A.; Zhong, Minghua; Zhou, Leonardo; Liu, Yu; Chen, Chong; Davé, Utpal; Kapur, Reuben; Batra, Sandeep; Zhang, Chi; Zhou, Jiehao; Fan, Jing; Wek, Ronald C.; Zhang, Ji; Pediatrics, School of Medicine
    Amino acid restriction has recently emerged as a compelling strategy to inhibit tumor growth. Recent work suggests that amino acids can regulate cellular signaling in addition to their role as biosynthetic substrates. Using lymphoid cancer cells as a model, we found that asparagine depletion acutely reduces the expression of c-MYC protein without changing its mRNA expression. Furthermore, asparagine depletion inhibits the translation of MYC mRNA without altering the rate of MYC protein degradation. Of interest, the inhibitory effect on MYC mRNA translation during asparagine depletion is not due to the activation of the general controlled nonderepressible 2 (GCN2) pathway and is not a consequence of the inhibition of global protein synthesis. In addition, both the 5' and 3' untranslated regions (UTRs) of MYC mRNA are not required for this inhibitory effect. Finally, using a MYC-driven mouse B cell lymphoma model, we found that shRNA inhibition of asparagine synthetase (ASNS) or pharmacological inhibition of asparagine production can significantly reduce the MYC protein expression and tumor growth when environmental asparagine becomes limiting. Since MYC is a critical oncogene, our results uncover a molecular connection between MYC mRNA translation and asparagine bioavailability and shed light on a potential to target MYC oncogene post-transcriptionally through asparagine restriction.
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    Asparagine starvation suppresses histone demethylation through iron depletion
    (Elsevier, 2023-03-16) Jiang, Jie; Srivastava, Sankalp; Liu, Sheng; Seim, Gretchen; Claude, Rodney; Zhong, Minghua; Cao, Sha; Davé, Utpal; Kapur, Reuben; Mosley, Amber L.; Zhang, Chi; Wan, Jun; Fan, Jing; Zhang, Ji; Pediatrics, School of Medicine
    Intracellular α-ketoglutarate is an indispensable substrate for the Jumonji family of histone demethylases (JHDMs) mediating most of the histone demethylation reactions. Since α-ketoglutarate is an intermediate of the tricarboxylic acid cycle and a product of transamination, its availability is governed by the metabolism of several amino acids. Here, we show that asparagine starvation suppresses global histone demethylation. This process is neither due to the change of expression of histone-modifying enzymes nor due to the change of intracellular levels of α-ketoglutarate. Rather, asparagine starvation reduces the intracellular pool of labile iron, a key co-factor for the JHDMs to function. Mechanistically, asparagine starvation suppresses the expression of the transferrin receptor to limit iron uptake. Furthermore, iron supplementation to the culture medium restores histone demethylation and alters gene expression to accelerate cell death upon asparagine depletion. These results suggest that suppressing iron-dependent histone demethylation is part of the cellular adaptive response to asparagine starvation.
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    Asparagine, a critical limiting metabolite during glutamine starvation
    (Taylor & Francis, 2018-04-11) Jiang, Jie; Pavlova, Natalya N.; Zhang, Ji; Pediatrics, School of Medicine
    A challenge of targeting glutamine metabolism in cancer is that tumor cells develop various strategies to adapt to glutamine limitation. We found that asparagine plays a critical role in supporting protein synthesis during glutamine starvation, highlighting a possible approach to optimize the therapeutic efficacy of targeting glutamine metabolism in cancer.
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    Asparagine: A Metabolite to Be Targeted in Cancers
    (MDPI, 2021-06-19) Jiang, Jie; Batra, Sandeep; Zhang, Ji; Pediatrics, School of Medicine
    Amino acids play central roles in cancer progression beyond their function as building blocks for protein synthesis. Thus, targeting amino acid acquisition and utilization has been proved to be therapeutically beneficial in various pre-clinical models. In this regard, depletion of circulating asparagine, a nonessential amino acid, by L-asparaginase has been used in treating pediatric acute lymphoblastic leukemia (ALL) for decades. Of interest, unlike most solid tumor cells, ALL cells lack the ability to synthesize their own asparagine de novo effectively. However, only until recently, growing evidence suggests that solid tumor cells strive to acquire adequate amounts of asparagine to support tumor progression. This process is subjected to the regulation at various levels, including oncogenic signal, tumor-niche interaction, intratumor heterogeneity and dietary accessibility. We will review the literature on L-asparaginase-based therapy as well as recent understanding of asparagine metabolism in solid tumor progression, with the hope of shedding light into a broader cancer therapeutic strategy by perturbing its acquisition and utilization.
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    Integrin α 5 Is Regulated by miR-218-5p in Endothelial Progenitor Cells
    (Wolters Kluwer, 2022) Liu, Jialing; Li, Yi; Lyu, Lingna; Xiao, Liang; Memon, Aliza A.; Yu, Xin; Halim, Arvin; Patel, Shivani; Osman, Abdikheyre; Yin, Wenqing; Jiang, Jie; Naini, Said; Lim, Kenneth; Zhang, Aifeng; Williams, Jonathan D.; Koester, Ruth; Qi, Kevin Z.; Fucci, Quynh-Anh; Ding, Lai; Chang, Steven; Patel, Ankit; Mori, Yutaro; Chaudhari, Advika; Bao, Aaron; Liu, Jia; Lu, Tzong-Shi; Siedlecki, Andrew; Medicine, School of Medicine
    Kidney endothelial cells are sensitive to hypoxic injury. This cell type expresses integrin α5 (ITGA5), which is essential to the Tie2 signaling cascade. The microRNA miR-218 is known to increase after hypoxia, but the microRNA’s role in regulating ITGA5 protein synthesis is unclear. In this study, the authors found that miR-218-5p specifically binds to ITGA5 mRNA in human kidney-derived endothelial progenitor cells (EPCs). In an animal model of ischemia/reperfusion injury, cells pretreated with an miR-218-5p mimic were delivered efficiently, whereas an animal model containing an miR-218-2 deletion specific to angioblasts resulted in kidney dysgenesis and impaired migration of mouse kidney-derived EPCs. Understanding the regulation of prominent signaling pathways in EPCs may inform optimization of therapeutic techniques for addressing kidney endothelial cell injury.
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    Promoter demethylation of the asparagine synthetase gene is required for ATF4-dependent adaptation to asparagine depletion
    (Elsevier, 2019-12-06) Jiang, Jie; Srivastava, Sankalp; Seim, Gretchen; Pavlova, Natalya N.; King, Bryan; Zou, Lihua; Zhang, Chi; Zhong, Minghua; Feng, Hui; Kapur, Reuben; Wek, Ronald C.; Fan, Jing; Zhang, Ji; Pediatrics, School of Medicine
    Tumor cells adapt to nutrient-limited environments by inducing gene expression that ensures adequate nutrients to sustain metabolic demands. For example, during amino acid limitations, ATF4 in the amino acid response induces expression of asparagine synthetase (ASNS), which provides for asparagine biosynthesis. Acute lymphoblastic leukemia (ALL) cells are sensitive to asparagine depletion, and administration of the asparagine depletion enzyme l-asparaginase is an important therapy option. ASNS expression can counterbalance l-asparaginase treatment by mitigating nutrient stress. Therefore, understanding the mechanisms regulating ASNS expression is important to define the adaptive processes underlying tumor progression and treatment. Here we show that DNA hypermethylation at the ASNS promoter prevents its transcriptional expression following asparagine depletion. Insufficient expression of ASNS leads to asparagine deficiency, which facilitates ATF4-independent induction of CCAAT-enhancer-binding protein homologous protein (CHOP), which triggers apoptosis. We conclude that chromatin accessibility is critical for ATF4 activity at the ASNS promoter, which can switch ALL cells from an ATF4-dependent adaptive response to ATF4-independent apoptosis during asparagine depletion. This work may also help explain why ALL cells are most sensitive to l-asparaginase treatment compared with other cancers.
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    Starve Cancer Cells of Glutamine: Break the Spell or Make a Hungry Monster?
    (MDPI, 2019-06-11) Jiang, Jie; Srivastava, Sankalp; Zhang, Ji; Biochemistry & Molecular Biology, IU School of Medicine
    Distinct from normal differentiated tissues, cancer cells reprogram nutrient uptake and utilization to accommodate their elevated demands for biosynthesis and energy production. A hallmark of these types of reprogramming is the increased utilization of, and dependency on glutamine, a nonessential amino acid, for cancer cell growth and survival. It is well-accepted that glutamine is a versatile biosynthetic substrate in cancer cells beyond its role as a proteinogenic amino acid. In addition, accumulating evidence suggests that glutamine metabolism is regulated by many factors, including tumor origin, oncogene/tumor suppressor status, epigenetic alternations and tumor microenvironment. However, despite the emerging understanding of why cancer cells depend on glutamine for growth and survival, the contribution of glutamine metabolism to tumor progression under physiological conditions is still under investigation, partially because the level of glutamine in the tumor environment is often found low. Since targeting glutamine acquisition and utilization has been proposed to be a new therapeutic strategy in cancer, it is central to understand how tumor cells respond and adapt to glutamine starvation for optimized therapeutic intervention. In this review, we first summarize the diverse usage of glutamine to support cancer cell growth and survival, and then focus our discussion on the influence of other nutrients on cancer cell adaptation to glutamine starvation as well as its implication in cancer therapy.