RNA methylation-mediated LINC01559 suppresses colorectal cancer progression by regulating the miR-106b-5p/PTEN axis

Long noncoding RNAs (lncRNAs) regulate multiple biological effects in cancers. Recently, RNA methylation has been found to modify not only coding RNAs but also some noncoding RNAs. How RNA methylation affects lncRNAs to affect colorectal cancer (CRC) progression remains elusive. The expression of LINC01559 was explored through RNA sequencing, quantitative real-time PCR (qRT-PCR) and in situ hybridization (ISH). The preliminary exploration of its function was performed using Western blotting (WB) and immunohistochemistry (IHC). Functional experiments in vitro and in vivo were conducted to explore the biological functions of LINC01559 in CRC. The LINC01559/miR-106-5p/PTEN axis was verified through fluorescence in situ hybridization (FISH), luciferase assays, and rescue experiments. RIP-sequencing, m6A RNA immunoprecipitation (MeRIP) assays and bioinformatic analysis were conducted to determine the upstream mechanism of LINC01559. The results showed that LINC01559 was downregulated in CRC compared with normal controls. Lower expression of LINC01559 in CRC patients predicted a poor prognosis. In addition, PTEN was found to be positively correlated with LINC01559, and miR-106b-5p could be the link between LINC01559 and PTEN. Then, silencing LINC01559 restored the malignant phenotype of CRC cells, while cotransfection of miR-106b-5p inhibitor neutralized this effect. Mechanistically, we found abundant m6A modification sites on LINC01559. Then, we uncovered these sites as potential targets of METTL3 through experiments in vivo. The results revealed a negative functional regulation of the LINC01559/miR-106b-5p/PTEN axis in CRC progression and explored a new mechanism of METTL3-mediated m6A modification on LINC01559. These results elucidate a novel potential therapeutic target for CRC treatment.     

Long noncoding RNA LINC00518 induces radioresistance by regulating glycolysis through an miR-33a-3p/HIF-1α negative feedback loop in melanoma

The long noncoding RNA, LINC00518, is highly expressed in various types of cancers and is involved in cancer progression. Although LINC00518 promotes the metastasis of cutaneous malignant melanoma (CMM), the mechanism underlaying its effects on CMM radiosensitivity remains unclear. In this study, LINC00518 expression was significantly upregulated in CMM samples, and LINC00518 levels were associated with poor prognosis of patients with CMM. Knockdown of LINC00518 in CMM cells significantly inhibited cell invasion, migration, proliferation, and clonogenicity. LINC00518-mediated invasion, migration, proliferation, and clonogenicity were negatively regulated by the microRNA, miR-33a-3p, in vitro, which increased sensitivity to radiotherapy via inhibition of the hypoxia-inducible factor 1α (HIF-1α)/lactate dehydrogenase A glycolysis axis. Additionally, HIF-1α recognized the miR-33a-3p promoter region and recruited histone deacetylase 2, which decreased the expression of miR-33a-3p and formed an LINC00518/miR-33a-3p/HIF-1α negative feedback loop. Furthermore, signaling with initially activated glycolysis and radioresistance in CMM cells was impaired by Santacruzamate A, a histone deacetylase inhibitor, and 2-deoxy-D-glucose, a glycolytic inhibitor. Lastly, knockdown of LINC00518 expression sensitized CMM cancer cells to radiotherapy in an in vivo subcutaneously implanted tumor model. In conclusion, LINC00518 was confirmed to be an oncogene in CMM, which induces radioresistance by regulating glycolysis through an miR-33a-3p/HIF-1α negative feedback loop. Our study, may provide a potential strategy to improve the treatment outcome of radiotherapy in CMM.Subject terms: Melanoma, Tumour biomarkers     

RIP1 maintains DNA integrity and cell proliferation by regulating PGC-1α-mediated mitochondrial oxidative phosphorylation and glycolysis

Aerobic glycolysis or the Warburg effect contributes to cancer cell proliferation; however, how this glucose metabolism pathway is precisely regulated remains elusive. Here we show that receptor-interacting protein 1 (RIP1), a cell death and survival signaling factor, regulates mitochondrial oxidative phosphorylation and aerobic glycolysis. Loss of RIP1 in lung cancer cells suppressed peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) expression, impairing mitochondrial oxidative phosphorylation and accelerating glycolysis, resulting in spontaneous DNA damage and p53-mediated cell proliferation inhibition. Thus, although aerobic glycolysis within a certain range favors cancer cell proliferation, excessive glycolysis causes cytostasis. Our data suggest that maintenance of glycolysis by RIP1 is pivotal to cancer cell energy homeostasis and DNA integrity and may be exploited for use in anticancer therapy.     

The Plasma Membrane Calcium Pump in Pancreatic Cancer Cells Exhibiting the Warburg Effect Relies on Glycolytic ATP

Evidence suggests that the plasma membrane Ca²⁺-ATPase (PMCA), which is critical for maintaining a low intracellular Ca²⁺ concentration ([Ca²⁺]_i), utilizes glycolytically derived ATP in pancreatic ductal adenocarcinoma (PDAC) and that inhibition of glycolysis in PDAC cell lines results in ATP depletion, PMCA inhibition, and an irreversible [Ca²⁺]_i overload. We explored whether this is a specific weakness of highly glycolytic PDAC by shifting PDAC cell (MIA PaCa-2 and PANC-1) metabolism from a highly glycolytic phenotype toward mitochondrial metabolism and assessing the effects of mitochondrial versus glycolytic inhibitors on ATP depletion, PMCA inhibition, and [Ca²⁺]_i overload. The highly glycolytic phenotype of these cells was first reversed by depriving MIA PaCa-2 and PANC-1 cells of glucose and supplementing with α-ketoisocaproate or galactose. These culture conditions resulted in a significant decrease in both glycolytic flux and proliferation rate, and conferred resistance to ATP depletion by glycolytic inhibition while sensitizing cells to mitochondrial inhibition. Moreover, in direct contrast to cells exhibiting a high glycolytic rate, glycolytic inhibition had no effect on PMCA activity and resting [Ca²⁺]_i in α-ketoisocaproate- and galactose-cultured cells, suggesting that the glycolytic dependence of the PMCA is a specific vulnerability of PDAC cells exhibiting the Warburg phenotype.     

LncRNA UNC5B-AS1对肺癌细胞黏附、侵袭及迁移的影响及其机制

目的:探讨长链非编码RNA(lncRNA) UNC5B-AS1调控miR-218-5p的表达影响肺癌细胞黏附、侵袭和迁移及其作用机制。方法:选取2017年6月至2019年6月在重庆三峡中心医院肿瘤科经手术切除的20例肺癌患者癌组织和对应癌旁组织标本,采用实时荧光定量PCR(qRT-PCR)检测肺癌组织和癌旁组织及其支气管上皮细胞HBE和不同肺癌细胞A549、H1437、H1975、H1299和H460中UNC5B-AS1的表达。将UNC5B-AS1 siRNA转染至肺癌A549细胞,采用黏附实验、Transwell侵袭实验及划痕实验检测下调UNC5B-AS1对A549细胞黏附、侵袭和迁移能力的影响; qRT-PCR和双荧光素酶报告基因检测实验鉴定UNC5B-AS1对miR-218-5p的靶向调控关系; Western blot检测上皮间质转化(EMT)相关蛋白表达情况。结果:肺癌组织和细胞中UNC5B-AS1表达显著高于癌旁组织和支气管上皮细胞(P<0.05),UNC5B-AS1在肺癌A549细胞中的表达量最高(P<0.05)。下调UNC5B-AS1的表达能够抑制A549细...     

Mutant p53 prevents GAPDH nuclear translocation in pancreatic cancer cells favoring glycolysis and 2-deoxyglucose sensitivity

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and devastating human malignancies. In about 70% of PDACs the tumor suppressor gene TP53 is mutated generally resulting in conformational changes of mutant p53 (mutp53) proteins, which acquire oncogenic functions triggering aggressiveness of cancers and alteration of energetic metabolism. Here, we demonstrate that mutant p53 prevents the nuclear translocation of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) stabilizing its cytoplasmic localization, thus supporting glycolysis of cancer cells and inhibiting cell death mechanisms mediated by nuclear GAPDH. We further show that the prevention of nuclear localization of GAPDH is mediated by both stimulation of AKT and repression of AMPK signaling, and is associated with the formation of the SIRT1:GAPDH complex. By using siRNA-GAPDH or an inhibitor of the enzyme, we functionally demonstrate that the maintenance of GAPDH in the cytosol has a critical impact on the anti-apoptotic and anti-autophagic effects driven by mutp53. Furthermore, the blockage of its mutp53-dependent cytoplasmic stabilization is able to restore the sensitivity of PDAC cells to the treatment with gemcitabine. Finally, our data suggest that mutp53-dependent enhanced glycolysis permits cancer cells to acquire sensitivity to anti-glycolytic drugs, such as 2-deoxyglucose, suggesting a potential personalized therapeutic approach in human cancers carrying mutant TP53 gene.     

A glycolysis-based ten-gene signature correlates with the clinical outcome,molecular subtype and IDH1 mutation in glioblastoma

Reprogrammed metabolism is a hallmark of cancer. Glioblastoma (GBM) tumor cells predominantly utilize aerobic glycolysis for the biogenesis of energy and intermediate nutrients. However, in GBM, the clinical significance of glycolysis and its underlying relations with the molecular features such as IDH1 mutation and subtype have not been elucidated yet. Herein, based on glioma datasets including TCGA (The Cancer Genome Atlas), REMBRANDT (Repository for Molecular Brain Neoplasia Data) and GSE16011, we established a glycolytic gene expression signature score (GGESS) by incorporating ten glycolytic genes. Then we performed survival analyses and investigated the correlations between GGESS and IDH1 mutation as well as the molecular subtypes in GBMs. The results showed that GGESS independently predicted unfavorable prognosis and poor response to chemotherapy of GBM patients. Notably, GGESS was high in GBMs of mesenchymal subtype but low in IDH1-mutant GBMs. Furthermore, we found that the promoter regions of tumor-promoting glycolytic genes were hypermethylated in IDH1-mutant GBMs. Finally, we found that high GGESS also predicted poor prognosis and poor response to chemotherapy when investigating IDH1-wildtype GBM patients only. Collectively, glycolysis represented by GGESS predicts unfavorable clinical outcome of GBM patients and is closely associated with mesenchymal subtype and IDH1 mutation in GBMs.     

Biomarkers of TGF-β Signaling Pathway and Prognosis of Pancreatic Cancer

Background

Transforming growth factor (TGF)-β signaling pathway, may act both as a tumor suppressor and as a tumor promoter in pancreatic cancer, depending on tumor stage and cellular context. TGF-β pathway has been under intensive investigation as a potential therapeutic target in the treatment of cancer. We hypothesized a correlation between TGF-βR2/SMAD4 expression in the tumor, plasma TGF-β1 ligand level, genetic variation in TGF-B pathway and prognosis of pancreatic cancer.

Method

We examined TGF-βR2 and SMAD4 protein expression in biopsy or surgical samples from 91 patients with pancreatic ductal adenocarcinoma (PDAC) using immunohistochemistry. Plasma level of TGF-β1 was measured in 644 patients with PDAC using ELISA. Twenty-eight single nucleotide polymorphisms (SNP) of the TGF-β1, TGF-β2, TGF-β3, TGF-βR1, TGF-βR2, and SMAD4 genes were determined in 1636 patients with PDAC using the Sequenom method. Correlation between protein expression in the tumor, plasma TGF-β1 level, and genotypes with overall survival (OS) was evaluated with Cox proportional regression models.

Results

The expression level of TGF-βR2 and SMAD4 as an independent marker was not associated with OS. However, patients with both low nuclear staining of TGF-βR2 and high nuclear staining of SMAD4 may have better survival (P = 0.06). The mean and median level of TGF-β1 was 15.44 (SD: 10.99) and 12.61 (interquartile range: 8.31 to 19.04) ng/ml respectively. Patients with advanced disease and in the upper quartile range of TGF-β1 level had significantly reduced survival than those with low levels (P = 0.02). A significant association of SMAD4 SNP rs113545983 with overall survival was observed (P<0.0001).

Conclusion

Our data provides valuable baseline information regarding the TGF-β pathway in pancreatic cancer, which can be utilized in targeted therapy clinical trials. High TGF-β1 plasma level, SMAD4 SNP or TGF-βR2/SMAD4 tumor protein expression may suggest a dependence on this pathway in patients with advanced pancreatic cancer.     

Maternal opioid use disorder: Placental transcriptome analysis for neonatal opioid withdrawal syndrome

Excessive prenatal opioid exposure may lead to the development of Neonatal Opioid Withdrawal Syndrome (NOWS). RNA-seq was done on 64 formalin-fixed paraffin-embedded placental tissue samples from 32 mothers with opioid use disorder, with newborns with NOWS that required treatment, and 32 prenatally unexposed controls. We identified 93 differentially expressed genes in the placentas of infants with NOWS compared to unexposed controls. There were 4 up- and 89 downregulated genes. Among these, 7 genes CYP1A1, APOB, RPH3A, NRXN1, LINC01206, AL157396.1, UNC80 achieved an FDR p-value of <0.01. The remaining 87 genes were significant with FDR p-value <0.05. The 4 upregulated, CYP1A1, FP671120.3, RAD1, RN7SL856P, and the 10 most significantly downregulated genes were RNA5SP364, GRIN2A, UNC5D, DMBT1P1, MIR3976HG, LINC02199, LINC02822, PANTR1, AC012178.1, CTNNA2. Ingenuity Pathway Analysis identified the 7 most likely to play an important role in the etiology of NOWS. Our study expands insights into the genetic mechanisms of NOWS development.     

Human steroid sulfatase enhances aerobic glycolysis through induction of HIF1α and glycolytic enzymes

Human steroid sulfatase (STS) has been linked with poor prognosis in steroid-associated tumors and represents an important clinical target in cancers, yet the mechanism of STS-induced carcinogenesis remains unclear. To correlate STS with cancer metabolism, we determined the effects of STS on aerobic glycolysis. STS overexpression increased cellular levels of lactic acid, the final product of aerobic glycolysis. Moreover, STS suppressed the oxygen consumption rate (OCR), which represents mitochondrial respiration. Inhibition of STS by the specific inhibitor STX064 recovered STS-induced OCR repression and lactic acid over-production. DHEA, but not DHEA-S, suppressed the OCR level and enhanced lactic acid production. To understand the molecular mechanism of STS-induced cancer metabolism, we measured the expression of glycolytic enzymes hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2), which was highly upregulated by STS and DHEA at both protein and mRNA levels. HIF1α is a key mediator of aerobic glycolysis, and STS enhanced HIF1α promoter activity, mRNA expression, and protein expression. Down-regulation of HIF1α by siRNA suppressed the HK2 and PKM2 expression induced by both STS and DHEA. HIF1α siRNA also recovered the OCR repression and lactic acid over-production induced by both STS and DHEA. To explore the mechanism in vivo, we produced transgenic mice overexpressing STS and found that STS expression was particularly enhanced in the lung. Consistent with our in vitro results, the expression of HIF1α, HK2, and PKM2 was also increased in mouse lung tissues. In conclusion, we suggest that STS may induce aerobic glycolysis through enhancing HIF1α expression.     

Signaling through the Phosphatidylinositol 3-Kinase (PI3K)/Mammalian Target of Rapamycin (mTOR) Axis Is Responsible for Aerobic Glycolysis mediated by Glucose Transporter in Epidermal Growth Factor Receptor (EGFR)-mutated Lung Adenocarcinoma

Oncogenic epidermal growth factor receptor (EGFR) signaling plays an important role in regulating global metabolic pathways, including aerobic glycolysis, the pentose phosphate pathway (PPP), and pyrimidine biosynthesis. However, the molecular mechanism by which EGFR signaling regulates cancer cell metabolism is still unclear. To elucidate how EGFR signaling is linked to metabolic activity, we investigated the involvement of the RAS/MEK/ERK and PI3K/AKT/mammalian target of rapamycin (mTOR) pathways on metabolic alteration in lung adenocarcinoma (LAD) cell lines with activating EGFR mutations. Although MEK inhibition did not alter lactate production and the extracellular acidification rate, PI3K/mTOR inhibitors significantly suppressed glycolysis in EGFR-mutant LAD cells. Moreover, a comprehensive metabolomics analysis revealed that the levels of glucose 6-phosphate and 6-phosphogluconate as early metabolites in glycolysis and PPP were decreased after inhibition of the PI3K/AKT/mTOR pathway, suggesting a link between PI3K signaling and the proper function of glucose transporters or hexokinases in glycolysis. Indeed, PI3K/mTOR inhibition effectively suppressed membrane localization of facilitative glucose transporter 1 (GLUT1), which, instead, accumulated in the cytoplasm. Finally, aerobic glycolysis and cell proliferation were down-regulated when GLUT1 gene expression was suppressed by RNAi. Taken together, these results suggest that PI3K/AKT/mTOR signaling is indispensable for the regulation of aerobic glycolysis in EGFR-mutated LAD cells.     

Stress eating and tuning out: Cancer cells re-wire metabolism to counter stress

Abstract

Cancer cells reprogram metabolism to maintain rapid proliferation under often stressful conditions. Glycolysis and glutaminolysis are two central pathways that fuel cancer metabolism. Allosteric regulation and metabolite driven post-translational modifications of key metabolic enzymes allow cancer cells glycolysis and glutaminolysis to respond to changes in nutrient availability and the tumor microenvironment. While increased aerobic glycolysis (the Warburg effect) has been a noted part of cancer metabolism for over 80 years, recent work has shown that the elevated levels of glycolytic intermediates are critical to cancer growth and metabolism due to their ability to feed into the anabolic pathways branching off glycolysis such as the pentose phosphate pathway and serine biosynthesis pathway. The key glycolytic enzymes phosphofructokinase-1 (PFK1), pyruvate kinase (PKM2) and phosphoglycerate mutase 1 (PGAM1) are regulated by upstream and downstream metabolites to balance glycolytic flux with flux through anabolic pathways. Glutamine regulation is tightly controlled by metabolic intermediates that allosterically inhibit and activate glutamate dehydrogenase, which fuels the tricarboxylic acid cycle by converting glutamine derived glutamate to α-ketoglutarate. The elucidation of these key allosteric regulatory hubs in cancer metabolism will be essential for understanding and predicting how cancer cells will respond to drugs that target metabolism. Additionally, identification of the structures involved in allosteric regulation will inform the design of anti-metabolism drugs which bypass the off-target effects of substrate mimics. Hence, this review aims to provide an overview of allosteric control of glycolysis and glutaminolysis.     

Glucose transporter 1-mediated glucose uptake is limiting for B-cell acute lymphoblastic leukemia anabolic metabolism and resistance to apoptosis

The metabolic profiles of cancer cells have long been acknowledged to be altered and to provide new therapeutic opportunities. In particular, a wide range of both solid and liquid tumors use aerobic glycolysis to supply energy and support cell growth. This metabolic program leads to high rates of glucose consumption through glycolysis with secretion of lactate even in the presence of oxygen. Identifying the limiting events in aerobic glycolysis and the response of cancer cells to metabolic inhibition is now essential to exploit this potential metabolic dependency. Here, we examine the role of glucose uptake and the glucose transporter Glut1 in the metabolism and metabolic stress response of BCR-Abl+ B-cell acute lymphoblastic leukemia cells (B-ALL). B-ALL cells were highly glycolytic and primary human B-ALL samples were dependent on glycolysis. We show B-ALL cells express multiple glucose transporters and conditional genetic deletion of Glut1 led to a partial loss of glucose uptake. This reduced glucose transport capacity, however, was sufficient to metabolically reprogram B-ALL cells to decrease anabolic and increase catabolic flux. Cell proliferation decreased and a limited degree of apoptosis was also observed. Importantly, Glut1-deficient B-ALL cells failed to accumulate in vivo and leukemic progression was suppressed by Glut1 deletion. Similarly, pharmacologic inhibition of aerobic glycolysis with moderate doses of 2-deoxyglucose (2-DG) slowed B-ALL cell proliferation, but extensive apoptosis only occurred at high doses. Nevertheless, 2-DG induced the pro-apoptotic protein Bim and sensitized B-ALL cells to the tyrosine kinase inhibitor Dasatinib in vivo. Together, these data show that despite expression of multiple glucose transporters, B-ALL cells are reliant on Glut1 to maintain aerobic glycolysis and anabolic metabolism. Further, partial inhibition of glucose metabolism is sufficient to sensitize cancer cells to specifically targeted therapies, suggesting inhibition of aerobic glycolysis as a plausible adjuvant approach for B-ALL therapies.Many cancer cells have elevated rates of glycolysis and lactate production even in the presence of oxygen. This program, termed aerobic glycolysis, occurs in a wide range of both solid and liquid tumors and is driven by oncogenic signals and microenvironmental pressures.¹ Aerobic glycolysis is proposed to allow metabolism in low oxygen tensions and to provide biosynthetic intermediates for cell growth. Indeed, aerobic glycolysis readily supports both generation of ATP and biosynthesis of lipids, nucleic acids, and amino acids.¹ Given the high rates of glucose consumption and aerobic glycolysis in most cancers, targeting glucose metabolism has become of significant interest as an approach to eliminate cancer cells. It is now important to establish mechanisms of aerobic glycolysis and the response of cancer cells to metabolic inhibition.The t(9;22) chromosomal translocation that generates the oncogenic kinase BCR-Abl occurs in ~25% of adult B-cell acute lymphoblastic leukemia cells (B-ALL) and is associated with poor prognosis.² The metabolic program of B-ALL cells is undefined, although diffuse large B-cell lymphoma (DLBCL) can either be highly glycolytic or use oxidative phosphorylation and mitochondrial metabolism.³ It has been suggested that BCR-Abl signaling is associated with elevated glucose metabolism, as BCR-Abl can promote glucose uptake and trafficking of glucose transporter Glut1 to the cell surface. Conversely, inhibition of BCR-Abl in leukemic cells suppresses glucose uptake and glycolysis.^{4, 5, 6, 7} This regulation of glucose metabolism may be critical for survival of BCR-Abl B-ALL, as enforced expression of Glut1 protected B-ALL cells from imatinib-induced apoptosis.⁸ These data show that BCR-Abl promotes glucose uptake and aerobic glycolysis, and BCR-Abl-transformed cells may rely on this pathway.Targeting glucose metabolism can have efficacy against a variety of cancers.⁹ Mechanistic understanding of cancer cell metabolic requirements or response to inhibition using pharmacologic approaches, however, has been limited. It has been shown using the glycolytic inhibitor 2-deoxyglucose (2-DG) or glucose deprivation culture conditions that inhibition of glucose metabolism impacts cancer cell growth and viability through several different mechanisms, including cell cycle arrest or cell death by activating AMPK pathway and inactivating mTOR signaling.¹⁰ Reduced glucose metabolism has also been found to impact the stability and synthesis of Bcl-2 family proteins. Glucose deprivation induces expression of pro-apoptotic molecules, including Bim^{7,11, 12, 13, 14, 15} and can induce apoptosis in cells transformed with oncogenic K-Ras through the unfolded protein response pathway.¹⁶Here we examine the mechanism and role of glucose uptake in B-ALL metabolism and leukemia progression by genetically targeting glucose transport. The Glut family of hexose transporters consists of 14 members¹⁷ and B-ALL cells expressed multiple family members. Conditional deletion of Glut1, however, demonstrated that B-ALL cells are reliant on this specific glucose transporter to sustain anabolic metabolism, proliferation, and resistance to cell death. Consistent with our data showing a key role for glucose uptake, we found that pharmacologic inhibition of glycolysis sensitized B-ALL cells to caspase activation and apoptosis to reduce leukemia burden in vivo. Glut1 and glucose uptake have a key role, therefore, to maintain BCR-Abl B-ALL cell growth and resistance to cell death.