Nutrient-deprived Conditions Research Articles

Autophagy in Osteosarcoma Cancer Stem Cells Is Critical Process which Can Be Targeted by the Antipsychotic Drug Thioridazine.

Simple SummaryCancer stem cells (CSCs) represent a minor population of cancer cells with stem cell-like properties and appear as a crucial target in oncology as they are the origin of relapses and resistance to current treatments. Autophagy, which allows the degradation and recycling of cellular components for survival purposes, has been shown to be upregulated in some CSCs, participating in the resistance of these cells. The aim of our study was to analyze the autophagy level and the consequences of targeting this process in osteosarcoma CSCs. Our results indicate that autophagy is a critical process in osteosarcoma CSCs and that targeting this pathway allows to switch their fate from survival to death.Cancer stem cells (CSCs) represent a minor population of cancer cells with stem cell-like properties which are able to fuel tumor growth and resist conventional treatments. Autophagy has been described to be upregulated in some CSCs and to play a crucial role by maintaining stem features and promoting resistance to both hostile microenvironments and treatments. Osteosarcoma (OS) is an aggressive bone cancer which mainly affects children and adolescents and autophagy in OS CSCs has been poorly studied. However, this is a very interesting case because autophagy is often deregulated in this cancer. In the present work, we used two OS cell lines showing different autophagy capacities to isolate CSC-enriched populations and to analyze the autophagy in basal and nutrient-deprived conditions. Our results indicate that autophagy is more efficient in CSCs populations compared to the parental cell lines, suggesting that autophagy is a critical process in OS CSCs. We also showed that the antipsychotic drug thioridazine is able to stimulate, and then impair autophagy in both CSC-enriched populations, leading to autosis, a cell death mediated by the Na+/K+ ATPase pump and triggered by dysregulated accumulation of autophagosomes. Taken together, our results indicate that autophagy is very active in OS CSCs and that targeting this pathway to switch their fate from survival to death could provide a novel strategy to eradicate these cells in osteosarcoma.

Human pancreatic cancer cells under nutrient deprivation are vulnerable to redox system inhibition

Large regions in tumor tissues, particularly pancreatic cancer, are hypoxic and nutrient-deprived because of unregulated cell growth and insufficient vascular supply. Certain cancer cells, such as those inside a tumor, can tolerate these severe conditions and survive for prolonged periods. We hypothesized that small molecular agents, which can preferentially reduce cancer cell survival under nutrient-deprived conditions, could function as anticancer drugs. In this study, we constructed a high-throughput screening system to identify such small molecules and screened chemical libraries and microbial culture extracts. We were able to determine that some small molecular compounds, such as penicillic acid, papyracillic acid, and auranofin, exhibit preferential cytotoxicity to human pancreatic cancer cells under nutrient-deprived compared with nutrient-sufficient conditions. Further analysis revealed that these compounds target to redox systems such as GSH and thioredoxin and induce accumulation of reactive oxygen species in nutrient-deprived cancer cells, potentially contributing to apoptosis under nutrient-deprived conditions. Nutrient-deficient cancer cells are often deficient in GSH; thus, they are susceptible to redox system inhibitors. Targeting redox systems might be an attractive therapeutic strategy under nutrient-deprived conditions of the tumor microenvironment.

S100A8 promotes chemoresistance via augmenting autophagy in B‑cell lymphoma cells.

B-cell lymphomas (BCLs) are malignant lymphoid tumours originating from the malignant proliferation and transformation of mature lymphocytes at various stages of differentiation and clonal expansion of the lymphatic and circulatory systems. Efforts to control or even eradicate BCLs are frequently hampered by the development of drug resistance. Autophagy is an evolutionarily conserved biological process of the energy metabolism. By degrading intracellular organelles and proteins, autophagy provides cells with biochemical reaction substrates for the maintenance of homeostasis under nutrient deprivation or other stressful conditions. Accumulating evidence indicates that autophagy plays an important role in chemotherapy resistance. S100A8 is an important member of the calcium-binding protein family that plays an important role in regulating tumour resistance to chemotherapy, while the specific molecular regulatory mechanisms remain unclear. In the present study, by employing three BCL cell lines (Daudi, SUDHL-4 and JeKo-1), it was demonstrated that BCL cells with a strong drug resistance also exhibited active autophagy. In addition, S100A8 was found to be crucial for regulating drug resistance and promoting autophagy in BCL cells. Interference of S100A8 significantly downregulated Bcl-2/adenovirus E1B 19-kDa protein-interacting protein 3 located in the mitochondria and endoplasmic reticulum to further inhibit autophagy. In addition, S100A8 interference markedly inhibited the formation of the BECN1-PI3KC3 complex and promoted B-cell lymphoma 2 expression, which collectively inhibited autophagy.

A new flavanone derivative from the rhizomes of Boesenbergia pandurata

From the methanolic extract of the rhizomes of Boesenbergia pandurata, a new flavanone derivative named (2R,7″S)-8-(1-phenyl-2-carboxyethyl)pinocembrin (1) and four known flavonoids (2–5) were isolated. Its absolute configuration was concluded by NMR and MS spectroscopic analysis, together with comparison between experimental and calculated ECD data. In turn, compound 1 exhibited strong cytotoxicity against the PANC-1 human pancreatic cancer cell line with a PC50 value of 6.4 µM under nutrient-deprived conditions, comparable with that of arctigenin (PC50, 0.83 µM).

CARM1 Regulates AMPK Signaling in Skeletal Muscle.

SummaryCoactivator-associated arginine methyltransferase 1 (CARM1) is an emerging mediator of skeletal muscle plasticity. We employed genetic, physiologic, and pharmacologic approaches to determine whether CARM1 regulates the master neuromuscular phenotypic modifier AMP-activated protein kinase (AMPK). CARM1 skeletal muscle-specific knockout (mKO) mice displayed reduced muscle mass and dysregulated autophagic and atrophic processes downstream of AMPK. We observed altered interactions between CARM1 and AMPK and its network, including forkhead box protein O1, during muscle disuse. CARM1 methylated AMPK during the early stages of muscle inactivity, whereas CARM1 mKO mitigated progression of denervation-induced atrophy and was accompanied by attenuated phosphorylation of AMPK targets such as unc-51 like autophagy-activating kinase 1Ser555. Lower acetyl-coenzyme A corboxylaseSer79 phosphorylation, as well as reduced peroxisome proliferator-activated receptor-γ coactivator-1α, was also observed in mKO animals following acute administration of the direct AMPK activator MK-8722. Our study suggests that targeting CARM1-AMPK interplay may have broad impacts on neuromuscular health and disease.

Influence of nutrient status on the biohydrogen and lipid productivity in Parachlorella kessleri: a biorefinery approach.

The commercial reality of microalgal biotechnology for the production of individual bioactives is constrained by the high cost of production and requires a biorefinery approach. In this investigation, we examined the influence of different nutrient deprivation (nitrogen (N), phosphorus (P), sulphur (S) and manganese (Mn)) on growth, chlorophyll a (Chl a), biohydrogen (H2) and fatty acid profiles in Parachlorella kessleri EMCCN 3073 under both aerobic and anaerobic conditions. Anaerobic conditions combined with the nutrient deprivation resulted in cell division blockage, reduction in Chl a and remarkable changes in pH, whereas a significant increase in the H2 production was observed after 24h. The highest cumulative H2 productivity was observed in N-deficient medium (300μL/L, day 9) followed by Mn-deficient medium (250μL/L, day 7). The highest H2 production rate (3.37μL/L/h) was achieved by Mn-deficient medium after 24h. In terms of fatty acid composition, P. kessleri exhibited a differential response to different nutrient stresses. Under aerobic conditions, N-deficient media resulted in the highest lipid content (119% compared to control, day 7), whereas earlier lipid induction at (1-3days) was observed with Mn- and S-deficient media with 18-91% and 25-34% increase, respectively, compared with the replete control. Meanwhile, higher lipid content was observed under anaerobic conditions combined with Mn-, N-, P- and S-deprived media (day 1) with 20%, 13%, 8% and 7% increases respectively compared with the control. This investigation, for the first time clearly, highlights the potential of P. kessleri as a sustainable biorefinery platform, for H2 and fatty acid bio-production under anaerobic conditions. KEY POINTS: • Parachlorella kessleri could provide a future sustainable biorefinery platform. • Nutrient-deprived anaerobic conditions blocked cell growth but differentially induced H2 production. • Nutrient status, under both aerobic/anaerobic conditions, alters lipids and fatty acids profile of P. kessleri. • Nutrient-deprived (N- and Mn-) anaerobic conditions: future biorefinery platform.

Nutrient Deprivation Promotes MCL-1 Degradation in an Autophagy-Independent Manner.

The antiapoptotic protein Mcl-1, which is an attractive target for cancer treatment, is degraded under nutrient deprivation conditions in different types of cancer. This process sensitizes cancer cells to chemotherapy. It has been found that nutrient deprivation leads to suppression of Mcl-1 synthesis; however, the mechanisms of Mcl-1 degradation under such conditions remain to be elucidated. In this study, we have investigated the contribution of autophagy and proteasomal degradation to the regulation of the level of Mcl-1 protein under nutrient deprivation conditions. We found that these circumstances cause a decrease in the level of Mcl-1 in cancer cells in a macroautophagy-independent manner via proteasomal degradation.

Transglutaminase Type 2 is Involved in the Hematopoietic Stem Cells Homeostasis.

Type 2 transglutaminase (TG2) is a multifunctional protein involved in various biological processes playing a key regulatory role in cell homeostasis such as cell death and autophagy. New evidence is emerging that support an important role of autophagy in regulating normal hematopoiesis. Prompted by these findings, in this study we investigated in vivo involvement of TG2 in mouse hematopoiesis under normal or nutrient deprivation conditions. We found that the number and rate of differentiation of bone marrow hematopoietic stem cell was decreased in the TG2 knockout mice. We present evidence showing that these effects on hematopoietic system are very likely due to the TG2-dependent impairment of autophagy. In fact, stimulation of autophagy by starvation is able to rescue the block of the differentiation of stem cells progenitors in the TG2 KO mice. It was also shown that the RhoA/ERK½ pathway, known to be essential for regulation of the bone marrow progenitor cells homeostasis, was significantly impaired in the absence of TG2. Hence, this study expanded our knowledge about TG2 discovering a role of this enzyme in regulation of hematopoiesis.

Transcriptional activation of macropinocytosis by the Hippo pathway following nutrient limitation.

Cancer cells must adapt metabolism to thrive despite nutrient limitations in the tumor microenvironment. In this issue of Genes & Development, King and colleagues (pp. 1345-1358) report a role for transcriptional regulators of the Hippo pathway to facilitate protein scavenging and support proliferation under some nutrient-deprived conditions.

Glycolytic inhibition by resveratrol prevents myoblast cell death caused by glucose deprivation and hypoxia; a possible application to the three-dimensional tissue construction

Decreased cell viability resulting from a severe condition of nutrients deprivation and hypoxia has been the major obstacle in three-dimensional (3D) tissue construction. Therefore, technical improvement which prevents cell death caused by starvation and low oxygen is desired for the development of large, thick tissues. We focused on the anti-glycolytic effect of resveratrol (RSV), a naturally-occurring polyphenol known as a caloric restriction mimetic, and investigated its cytoprotective effect in two-dimensional (2D) and 3D-cell culture using H9c2 rat myoblast cells. Glucose deprivation by culturing with low glucose media caused time- and dose-dependent cell death in H9c2 cells. In contrast, RSV treatment at 100μM significantly increased the cell viability by preventing cell death. RSV showed anti-glycolytic effect associated with a down-regulation of glycolytic genes (GLUT1, PKM2) and glucose uptake activity, and increased the activation of AMP-activated protein kinase (AMPK), an essential cellular energy sensor activated in the condition of energy deprivation. RSV treatment markedly improved the viability of myoblast cells cultured in a hypoxic, low glucose condition and attenuated the up-regulation of glycolytic genes by hypoxic response. In 3D-cultured model, spheroids constructed with RSV-treated cells showed improved cell viability and intact histological appearance compared with control. These results suggest that glycolytic inhibition by RSV decreases the glucose usage of myoblast cells, therefore, prevents cell death caused by nutrient deprivation and hypoxic condition. Our finding provides useful information to improve cell viability in a condition that nutrients and oxygen are low in supply, and be a possible application to the 3D-tissue construction.

562 THE EFFECT OF IONISING-RADIATION AND THE TUMOUR MICRO-ENVIRONMENT (TME) ON TREATMENT NAIVE ESOPHAGEAL ADENOCARCINOMA PATIENT T CELL FUNCTION AND ACTIVITY.

Abstract There is extensive literature demonstrating CD8+ T cells are essential for initial tumour control following radiation, however, effects are reduced after time due to T cell exhaustion and a lack of release Damage Associated Molecular Patterns (DAMPS) which are essential for anti-tumour immune responses. In vivo, activated T-cells migrate to the tumour site within the field of irradiation, however translational studies on the effects of radiotherapy on T-cell activation, function and activity are lacking. Methods EAC patient (n = 6) PBMCs were isolated by density centrifugation in Ficoll Paque. T cells were activated and were irradiated at 1.8Gy, 3.6Gy bolus dosing and fractionation for 72 hrs. A panel of immune checkpoints, DAMPS, activation markers, and cytokines were assessed by flow cytometry. To determine the effect of the TME on T cells, PBMCs were cultured under conditions of nutrient deprivation (No Glucose & No Glutamine) under conditions of normoxia and hypoxia. We then ran the aforementioned panel by flow cytometry. We also activated PBMCs with immune checkpoint blockers to determine its effects on T cell expansion and survival. Results 3.6Gy induced a significantly higher expression of DAPMS (Fig 1 p < 0.001); Calreticulin and HMGB1, most notably under conditions of nutrient deprivation (p < 0.001). Ionising radiation also resulted in an increase in the expression of cytokines and importantly in the context of targeted therapy, IR at both the conventional 1.8Gy and 3.6Gy induced a higher expression of checkpoints PD-1, PD-L1, TIGIT, and TIM-3 (p < 0.001). Interestingly, when T cells are activated in the presence of ICB (Atezolizumab, Pembrolizumab, Nivolumab), it increases the rate of T cell expansion, and enhances their survival compared to T cell activated only. (p < 0.001). Conclusion This work demonstrates the impact of clinically utilised fractions of radiation, and conditions of the TME on T cell function and activity, with improved T cell expansion and survival in the presence of ICB’s suggesting it may be a feasible combination therapy as an adjunct to radiotherapy.

Qualitative and Quantitative Assessment of Biodiesel Derived from Microalgae

A modular experiment for upper-level undergraduate students is presented, featuring the product cycle and process evaluating the quality and quantity of biodiesel obtained from a microalgae feedstock grown under carbon-supplemented and nutrient-deprived conditions. Batch reactors are used to cultivate and harvest microalgae, which undergo acid-catalyzed in situ transesterification to produce biodiesel. Methods are presented to quantify yield and analyze products via gas chromatography–mass spectroscopy. With an awareness of the limited time available in a teaching laboratory, this experiment was designed and successfully implemented in an undergraduate biochemistry course over four sessions. Reflux reactions were performed in hermetically sealed microwave vials, eliminating water usage and reducing glass breakage. Learning objectives were assessed by postcontent quizzes, and written reports using a rubric based on Bloom’s taxonomy, results of which indicate a demonstration of the higher-order cognitive abilities of Evaluation and Analysis. The ability to biochemically engineer cultivation conditions to influence lipid production gives this experiment the potential to be offered as a course-embedded undergraduate research experience (CURE) project. This easily adoptable experiment offers an engaging opportunity for students to experience the technical and societal aspects of emerging biofuel technologies.

Abstract 3801: Oxidative stress induces glutamine-dependent GD2+ triple negative breast cancer stem cells

Abstract Breast cancer stem cells (BCSCs) have been shown to be associated with tumor recurrence, metastasis and drug resistance. We reported that the ganglioside GD2 selectively identifies BCSCs and its over-expression in Triple-Negative Breast Cancer (TNBC). However, the factors regulating GD2+ BCSCs in a growing tumor are not known. Here we hypothesize that nutrient deprivation-induced oxidative stress upregulates GD2+ BCSCs in TNBC. TNBC cell lines including SUM159 and MDA-MB-231 were cultured under different nutrient-deprived conditions and analyzed for GD2 expression by flow cytometry. We have identified a steady increase of GD2+ cells from 5%±2% on day 3 to 20%±5% on day 6 in cells cultured in nutrient deprived condition. We further performed the in vivo by injecting GFP+ MDA-MB-231 cells into NSG mice and measured GD2+ expression in the growing tumor once a week. Interestingly, we also noticed a positive correlation between the percentage of GD2+ cells and tumor volume in vivo with r=0.9829 and p<0.0004 suggesting nutrient deprived conditions in the growing tumors results in higher GD2 expression. Next, the cells were cultured in medium with or without glucose or media containing 2-deoxy glucose (2DG, glycolysis inhibitor). We found that the percentage of GD2+ cells increased 2-fold in the absence of glucose or in the presence of 2DG (10mM) compared to cells cultured with glucose (6g/L) or without 2DG, suggesting that glucose deprivation enhances GD2 biosynthesis in TNBC cells. Global metabolomics profiling using liquid chromatography-mass spectrometry followed by KEGG pathway analysis identified signatures such as glutathione mediated detoxification and glutathione biosynthesis to be most highly upregulated in GD2+ compared to GD2- cells. As glutamine is a key precursor for glutathione biosynthesis, we cultured SUM159 and MDA-MB-231 cells in media with or without glutamine and found that the percentage of GD2+ cells positively correlates with glutamine concentration in the medium. Next, to target glutamine metabolism, we treated TNBC cells with glutaminase inhibitor, CB-839 or glutamine transporter inhibitor, V9302. This resulted in a 70-80% reduction of GD2 expression in a dose dependent manner. CB-839 and V9302 also inhibited mammosphere formation by 40-50% and increased reactive oxygen species (ROS) in a dose-dependent manner in TNBC cells. In conclusion, oxidative stress results in GD2+ BCSC phenotype in TNBC cells. Inhibition of glutamine uptake or its utilization by V9302 or CB-839 inhibits GD2+ BCSC phenotype and alters redox homeostasis in BCSCs by inducing ROS levels. Targeting glutamine transporter or glutaminase could complement conventional chemotherapy by targeting BCSCs in TNBC. Citation Format: Appalaraju Jaggupilli, Stanely J. Ly, Roshan Borkar, Khoa Nguyen, Bin Yuan, Nagireddy Putluri, Michael Andreeff, V. Lokesh Battula. Oxidative stress induces glutamine-dependent GD2+ triple negative breast cancer stem cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3801.

Exploring the Metabolic Vulnerabilities of Epithelial-Mesenchymal Transition in Breast Cancer.

Metastasis and drug resistance are the leading causes of death for breast cancer patients. Epithelial–mesenchymal transition (EMT), a transition from polarized epithelial cells to motile mesenchymal cells mediated by a series of activation signals, confers breast tumor cells with enhanced stem cell, invasive, and metastatic properties. Metabolic reprogramming is an emerging hallmark of cancer cells, which have a complex mutual effect with EMT process. Under hypoxic and nutrient-deprived conditions, metabolic rewiring can rapidly provide ATP and sufficient metabolic intermediates for fueling breast cancer metastasis and progression. In this review, we primarily focus on how these altered metabolic phenotypes of breast tumor cells activate the EMT transcription factors and induce the EMT process to further promote metastasis and resistance to therapy. This review is divided to glucose, lipid, and amino acid metabolism to explore for potential metabolic vulnerabilities, which may provide new insights for blocking the EMT process in breast cancer.

Leptospira interrogans Retains Direct Virulence After Long Starvation in Water.

Mostly studied as a zoonosis, leptospirosis is also an environment-borne infection and most human cases originate from soil or water contaminations. Yet, only few studies have been interested in the survival of pathogenic Leptospira in freshwater. In this study, water microcosms were designed to evaluate the survival and virulence of Leptospira spp. for 2years. Four commercial bottled drinking waters and a non-ionized water, all previously filter-sterilized, were studied. Either one of two Leptospira interrogans strains, one Leptospira borgpetersenii strain, or a saprophytic Leptospira biflexa was inoculated in these waters under nutrient-deprived conditions. Molecular, microscopic and cultural approaches were used to study Leptospira survival. Direct virulence of the pathogens was assessed using animal challenge without re-culturing. Our results confirmed the capacity of pathogenic Leptospira to survive for more than a year in water. In addition, we showed the ability of L. interrogans in nutrient-deprived conditions to directly cause systemic infection in susceptible animals. To our knowledge, this is the first report of direct infection of a susceptible host with Leptospira following a long starvation and survival period in nutrient-deprived water. Our results also suggest that Leptospira turned into a physiological "survival" state in harsh freshwater conditions. These data are of prime importance considering that freshwater is a major source of Leptospira infections. Environmental survival and virulence of pathogenic Leptospira spp. are becoming a crucial challenge to determine the environmental risk and adopt relevant prevention and control strategies.

Role of Proton-Coupled Monocarboxylate Transporters in Cancer: From Metabolic Crosstalk to Therapeutic Potential.

Proton-coupled monocarboxylate transporters (MCTs), representing the first four isoforms of the SLC16A gene family, mainly participate in the transport of lactate, pyruvate, and other monocarboxylates. Cancer cells exhibit a metabolic shift from oxidative metabolism to an enhanced glycolytic phenotype, leading to a higher production of lactate in the cytoplasm. Excessive accumulation of lactate threatens the survival of cancer cells, and the overexpression of proton-coupled MCTs observed in multiple types of cancer facilitates enhanced export of lactate from highly glycolytic cancer cells. Proton-coupled MCTs not only play critical roles in the metabolic symbiosis between hypoxic and normoxic cancer cells within tumors but also mediate metabolic interaction between cancer cells and cancer-associated stromal cells. Of the four proton-coupled MCTs, MCT1 and MCT4 are the predominantly expressed isoforms in cancer and have been identified as potential therapeutic targets in cancer. Therefore, in this review, we primarily focus on the roles of MCT1 and MCT4 in the metabolic reprogramming of cancer cells under hypoxic and nutrient-deprived conditions. Additionally, we discuss how MCT1 and MCT4 serve as metabolic links between cancer cells and cancer-associated stromal cells via transport of crucial monocarboxylates, as well as present emerging opportunities and challenges in targeting MCT1 and MCT4 for cancer treatment.

Chemical constituents of Callistemon citrinus from Egypt and their antiausterity activity against PANC-1 human pancreatic cancer cell line

Human pancreatic cancer is resistant to almost all conventional chemotherapeutic agents. It is known to proliferate aggressively within hypovascular tumor microenvironment by exhibiting remarkable tolerance to nutrition starvation, a phenomenon termed as “austerity”. Search for the new agents that eliminate the tolerance of cancer cells to nutrition starvation is a promising strategy in anticancer drug discovery. In this study, two new meroterpenoids named callistrilones O and P (1 and 2) together with eight known triterpenes (3–10) were isolated from the active dichloromethane extract of Callistemon citrinus leaves. The structure elucidation of the new compounds was achieved by HRFABMS, 1D, 2D NMR, and ECD quantum calculations. All isolated compounds were tested for their preferential cytotoxicity against PANC-1 human pancreatic cancer cells. Among these, callistrilone O (1) exhibited the most potent preferential cytotoxicity with a PC50 value of 0.3 nM, the strongest activity with over 2000 times potent than the positive control arctigenin. Callistrilone O (1) induced dramatic alterations in PANC-1 cell morphology leading to cell death under nutrient-deprived conditions. Compound 1 also inhibited PANC-1 cell migration and -PANC-1 colony formation under the nutrient-rich condition.

Effect of low dose of berberine on the radioresistance of cervical cancer cells via a PI3K/HIF-1 pathway under nutrient-deprived conditions

Purpose: Radiotherapy (RT) is one of the major treatments of cervical cancer. Although the prognosis of clinical cervical cancer becomes better in recent years, some patients still suffer from the recurrence and metastasis. Insufficiency of glucose and oxygen supply could increase the radioresistance of cervical cancer cells through regulating hypoxia-inducible factor 1 (HIF-1) in tumor microenvironment and glucose metabolism. And, berberine can regulate HIF-1. However, how berberine regulates tumor microenvironment and radioresistance through HIF-1 remains to be elucidated.Materials and methods: The human HeLa cervical cancer cells were treated with berberine and radiation under the high and low concentrations of glucose and oxygen, respectively. The survival of cells was tested by CCK-8 assay and colony formation assay. We investigated the PI3K- and IDH3α-related pathway molecules that may regulate HIF-1α by qPCR and western blot. Differentially expressed genes (DEGs) were identified by integrating five related cohort profile datasets. Protein–protein interaction (PPI) network analyses of DEGs related to HIF-1α were conducted by using the STRING database and Cytoscape software.Results: Berberine dramatically damaged HeLa cells under hypoxic and low-glucose conditions compared with the normoxic and high-glucose conditions. The clonogenic assay indicated that the application of berberine decreased the number of colony counts compared to the negative control. Low doses of berberine might decrease the level of phospho-PI3K and HIF-1α under the nutrient-deprived conditions. Moreover, we found that most of the differentially expressed genes which were related to CDKN1B were the downstream molecules regulated by HIF-1α.Conclusion: The results indicated that berberine could dramatically overcome the low-glucose and hypoxia-induced radioresistance. And the regulation berberine on nutrition-deficient conditions might involve in PI3K/HIF-1 pathway. Thus, the interference of glucose metabolism by berberine might be an attractive method to eliminate radioresistant cells and improve radiotherapy efficacy.

SAPK2 contributes to rice yield by modulating nitrogen metabolic processes under reproductive stage drought stress

BackgroundThe sucrose non-fermenting 1-related kinases 2 (SnRK2s) play important roles in osmotic stress responses in A. thaliana and rice (Oryza sativa L.). Osmotic stress/ABA–activated protein kinase 2 (SAPK2) is a member of SnRK2s subclass II in rice, but its function in rice yield under drought stress is unclear.ResultsCompared with wild-type (Oryza.Sativa L.spp.japonica, WT) plants, the sapk2 rice mutant lines were shorter and produced fewer grains per panicle, smaller grains and lower grain yield under reproductive stage drought stress (RDS). Subsequent analysis suggested that SAPK2 considerably influences the nitrogen, phosphorus, and potassium contents of rice grains. The examination of rice seedling growth and development under nutrient-deprived conditions (−N, −K, and − P) proved that SAPK2 can significantly affect rice seedling growth and root development in hydroponic cultures lacking N and K. Moreover, the NO3− influx rate and nitrate concentration analysis indicated that SAPK2 promotes nitrate uptake and assimilation by regulating nitrate-related transporters.ConclusionThese results suggest that SAPK2 could enhance grain production by regulating nitrogen utilization efficiency under RDS. Our work provided insights to breeding drought tolerant rice with high nutrient uptake.

AMPK Profiling in Rodent and Human Pancreatic Beta-Cells under Nutrient-Rich Metabolic Stress

Chronic exposure of pancreatic β-cells to elevated nutrient levels impairs their function and potentially induces apoptosis. Like in other cell types, AMPK is activated in β-cells under conditions of nutrient deprivation, while little is known on AMPK responses to metabolic stresses. Here, we first reviewed recent studies on the role of AMPK activation in β-cells. Then, we investigated the expression profile of AMPK pathways in β-cells following metabolic stresses. INS-1E β-cells and human islets were exposed for 3 days to glucose (5.5–25 mM), palmitate or oleate (0.4 mM), and fructose (5.5 mM). Following these treatments, we analyzed transcript levels of INS-1E β-cells by qRT-PCR and of human islets by RNA-Seq; with a special focus on AMPK-associated genes, such as the AMPK catalytic subunits α1 (Prkaa1) and α2 (Prkaa2). AMPKα and pAMPKα were also evaluated at the protein level by immunoblotting. Chronic exposure to the different metabolic stresses, known to alter glucose-stimulated insulin secretion, did not change AMPK expression, either in insulinoma cells or in human islets. Expression profile of the six AMPK subunits was marginally modified by the different diabetogenic conditions. However, the expression of some upstream kinases and downstream AMPK targets, including K-ATP channel subunits, exhibited stress-specific signatures. Interestingly, at the protein level, chronic fructose treatment favored fasting-like phenotype in human islets, as witnessed by AMPK activation. Collectively, previously published and present data indicate that, in the β-cell, AMPK activation might be implicated in the pre-diabetic state, potentially as a protective mechanism.