PGC1β regulates multiple myeloma tumor growth through LDHA-mediated glycolytic metabolism

Anti-leukemia effects of omipalisib in acute myeloid leukemia: inhibition of PI3K/AKT/mTOR signaling and suppression of mitochondrial biogenesis

Omipalisib (GSK2126458), a potent dual PI3K/mTOR inhibitor, is reported to exhibit anti-tumor effect in several kinds of cancers. More than 50% of acute myeloid leukemia (AML) patients display a hyperactivation of PI3K/AKT/mTOR signaling. We investigated the anti-proliferative effect of omipalisib in AML cell lines with varied genetic backgrounds. The OCI-AML3 and THP-1 cell lines had a significant response to omipalisib, with IC50 values of 17.45 nM and 8.93 nM, respectively. We integrated transcriptomic profile and metabolomic analyses, and followed by gene set enrichment analysis (GSEA) and metabolite enrichment analysis. Our findings showed that in addition to inhibiting PI3K/AKT/mTOR signaling and inducing cell cycle arrest at the G0/G1 phase, omipalisib also suppressed mitochondrial respiration and biogenesis. Furthermore, omipalisib downregulated several genes associated with serine, glycine, threonine, and glutathione metabolism, and decreased their protein and glutathione levels. In vivo experiments revealed that omipalisib significantly inhibited tumor growth and prolonged mouse survival without weight loss. Gedatolisib and dactolisib, another two PI3K/mTOR inhibitors, exerted similar effects without affecting mitochondria biogenesis. These results highlight the multifaceted anti-leukemic effect of omipalisib, revealing its potential as a novel therapeutic agent in AML treatment.

The Expression of Two Distinct Sets of Glycolytic Enzymes Reveals Differential Effects of Glycolytic Reprogramming on Pancreatic Ductal Tumorigenesis in Mice

Pancreatic ductal adenocarcinoma (PDAC) is associated with enhanced aerobic glycolysis through elevated glucose uptake and the upregulated expression of genes encoding rate-limiting glycolytic enzymes. However, the direct impact of altered glycolytic pathways on pancreatic tumor progression has not been thoroughly investigated. Here, we utilized two strains of BAC transgenic mice with pancreatic expression of two distinct sets of glycolytic genes each arranged in a polycistronic fashion (PFKFB3-HK2-GLUT1 and LDHA-PDK1, respectively) to investigate the role of altered glycolysis on the development of pancreatic ductal tumor development in the Pdx1-Cre; LSL-KrasG12D mice. The overexpression of the two sets of glycolytic genes exhibited no significant effects on tumor development in the 4-5-month-old mice (the PanIN2 lesions stage). In the 9-10-month-old mice, the overexpression of PFKFB3-HK2-GLUT1 significantly accelerated PanIN3 progression, exhibiting elevated levels of ductal cell marker CK19 and tumor fibrosis. Surprisingly, the overexpression of LDHA-PDK1 significantly attenuated the progression of PanIN3 in the 9-10-month-old mice with significantly downregulated levels of CK19 and fibrosis. Therefore, distinct set of glycolytic enzymes that are involved in different glycolytic routes exhibited contrasting effects on pancreatic ductal tumor development depending on the tumor stages, providing novel insights into the complexity of the glycolytic pathway in the perspective of PDAC development and therapy.

Mitochondrial dysfunction and drug targets in multiple myeloma

Multiple myeloma (MM) is the second most common hematological cancer that has no cure. Although currently there are several novel drugs, most MM patients experience drug resistance and disease relapse. The results of previous studies suggest that aberrant mitochondrial function may contribute to tumor progression and drug resistance. Mitochondrial DNA mutations and metabolic reprogramming have been reported in MM patients. Several preclinical and clinical studies have shown encouraging results of mitochondria-targeting therapy in MM patients. In this review, we have summarized our current understanding of mitochondrial biology in MM. More importantly, we have reviewed mitochondrial targeting strategies in MM treatment.

Shutting off the fuel supply to target metabolic vulnerabilities in multiple myeloma

Pathways that govern cellular bioenergetics are deregulated in tumor cells and represent a hallmark of cancer. Tumor cells have the capacity to reprogram pathways that control nutrient acquisition, anabolism and catabolism to enhance their growth and survival. Tumorigenesis requires the autonomous reprogramming of key metabolic pathways that obtain, generate and produce metabolites from a nutrient-deprived tumor microenvironment to meet the increased bioenergetic demands of cancer cells. Intra- and extracellular factors also have a profound effect on gene expression to drive metabolic pathway reprogramming in not only cancer cells but also surrounding cell types that contribute to anti-tumor immunity. Despite a vast amount of genetic and histologic heterogeneity within and between cancer types, a finite set of pathways are commonly deregulated to support anabolism, catabolism and redox balance. Multiple myeloma (MM) is the second most common hematologic malignancy in adults and remains incurable in the vast majority of patients. Genetic events and the hypoxic bone marrow milieu deregulate glycolysis, glutaminolysis and fatty acid synthesis in MM cells to promote their proliferation, survival, metastasis, drug resistance and evasion of immunosurveillance. Here, we discuss mechanisms that disrupt metabolic pathways in MM cells to support the development of therapeutic resistance and thwart the effects of anti-myeloma immunity. A better understanding of the events that reprogram metabolism in myeloma and immune cells may reveal unforeseen vulnerabilities and advance the rational design of drug cocktails that improve patient survival.

EBV and Lymphomagenesis

The clinical significance of Epstein–Barr virus (EBV) cannot be understated. Not only does it infect approximately 90% of the world’s population, but it is also associated with numerous pathologies. Diseases linked to this virus include hematologic malignancies such as diffuse large B-cell lymphoma, Hodgkin lymphoma, Burkitt lymphoma, primary CNS lymphoma, and NK/T-cell lymphoma, epithelial malignancies such as nasopharyngeal carcinoma and gastric cancer, autoimmune diseases such as multiple sclerosis, Graves’ disease, and lupus. While treatment for these disease states is ever evolving, much work remains to more fully elucidate the relationship between EBV, its associated disease states, and their treatments. This paper begins with an overview of EBV latency and latency-associated proteins. It will then review EBV’s contributions to select hematologic malignancies with a focus on the contribution of latent proteins as well as their associated management.

LMP1 mediates tumorigenesis through persistent epigenetic modifications and PGC1β upregulation

Latent membrane protein 1 (LMP1), which is encoded by the Epstein‑Barr virus (EBV), has been considered as an oncogene, although the detailed mechanism behind its function remains unclear. It has been previously reported that LMP1 promotes tumorigenesis by upregulation of peroxisome proliferator‑activated receptor‑γ coactivator‑1β (PGC1β). The present study aimed to investigate the potential mechanism for transient EBV/LMP1 exposure‑mediated persistent PGC1β expression and subsequent tumorigenesis through modification of mitochondrial function. Luciferase reporter assay, chromatin immunoprecipitation and DNA mutation techniques were used to evaluate the PGC1β‑mediated expression of dynamin‑related protein 1 (DRP1). Tumorigenesis was evaluated by gene expression, oxidative stress, mitochondrial function and in vitro cellular proliferation assays. The potential effects of EBV, LMP1 and PGC1β on tumor growth were evaluated in an in vivo xenograft mouse model. The present in vitro experiments showed that LMP1 knockdown did not affect PGC1β expression or subsequent cell proliferation in EBV‑positive tumor cells. PGC1β regulated DRP1 expression by coactivation of GA‑binding protein α and nuclear respiratory factor 1 located on the DRP1 promoter, subsequently modulating mitochondrial fission. Transient exposure of either EBV or LMP1 in human hematopoietic stem cells caused persistent epigenetic changes and PGC1β upregulation after long‑term cell culture even in the absence of EBV/LMP1, which decreased oxidative stress, and potentiated mitochondrial function and cell proliferation in vitro. Enhanced tumor growth and shortened survival were subsequently observed in vivo. It was concluded that PGC1β expression and subsequent cell proliferation were independent from LMP1 in EBV‑positive tumor cells. PGC1β modulated mitochondria fission by regulation of DRP1 expression. Transient EBV/LMP1 exposure caused persistent PGC1β expression, triggering tumor growth in the absence of LMP1. The present study proposes a novel mechanism for transient EBV/LMP1 exposure‑mediated tumorigenesis through persistent epigenetic changes and PGC1β upregulation, uncovering the reason why numerous forms of lymphoma exhibit upregulated PGC1β expression, but are devoid of EBV/LMP1.

LDHA as a regulator of T cell fate and its mechanisms in disease

T cells are the main force of anti-infection and antitumor and are also involved in autoimmune diseases. During the development of these diseases, T cells need to rapidly produce large amounts of energy to satisfy their activation, proliferation, and differentiation. In this review, we introduced lactate dehydrogenase A(LDHA), predominantly involved in glycolysis, which provides energy for T cells and plays a dual role in disease by mediating lactate production, non-classical enzyme activity, and oxidative stress. Mechanistically, the signaling molecule can interact with the LDHA promoter or regulate LDHA activity through post-translational modifications. These latest findings suggest that modulation of LDHA may have considerable therapeutic effects in diseases where T-cell activation is an important pathogenesis.

Metabolic features of myeloma cells in the context of bone microenvironment: Implication for the pathophysiology and clinic of myeloma bone disease

Multiple myeloma (MM) is a hematological malignancy characterized by the accumulation of malignant plasma cells (PCs) into the bone marrow (BM). The complex interaction between the BM microenvironment and MM PCs can lead to severe impairment of bone remodeling. Indeed, the BM microenvironment exerts a critical role in the survival of malignant PCs. Growing evidence indicates that MM cells have several metabolic features including enhanced glycolysis and an increase in lactate production through the upregulation of glucose transporters and enzymes. More recently, it has been reported that MM cells arehighly glutamine addicted. Interestingly, these metabolic changes in MM cells may affect BM microenvironment cells by altering the differentiation process of osteoblasts from mesenchymal stromal cells. The identification of glutamine metabolism alterations in MM cells and bone microenvironment may provide a rationale to design new therapeutic approaches and diagnostic tools. The osteolytic lesions are the most frequent clinical features in MM patients, often characterized by pathological fractures and acute pain. The use of the newer imaging techniques such as Magnetic Resonance Imaging (MRI) and combined Positron Emission Tomography (PET) and Computerized Tomography (CT) has been introduced into clinical practice to better define the skeletal involvement. Currently, the PET/CT with ¹⁸F-fluorodeoxyglucose (FDG) is the diagnostic gold standard to detect active MM bone disease due to the high glycolytic activity of MM cells. However, new tracers are actively under investigation because a portion of MM patients remains negative at the skeletal level by ¹⁸F-FDG. In this review, we will summarize the existing knowledge on the metabolic alterations of MM cells considering their impact on the BM microenvironment cells and particularly in the subsequent formation of osteolytic bone lesions. Based on this, we will discuss the identification of possible new druggable targets and the use of novel metabolic targets for PET imaging in the detection of skeletal lesions, in the staging and treatment response of MM patients.

Metabolic cross-talk within the bone marrow milieu: focus on multiple myeloma

Cancer cells are well-known for their capacity to adapt their metabolism to their increasing energy demands which is necessary for tumor progression. This is no different for Multiple Myeloma (MM), a hematological cancer which develops in the bone marrow (BM), whereby the malignant plasma cells accumulate and impair normal BM functions. It has become clear that the hypoxic BM environment contributes to metabolic rewiring of the MM cells, including changes in metabolite levels, increased/decreased activity of metabolic enzymes and metabolic shifts. These adaptations will lead to a pro-tumoral environment stimulating MM growth and drug resistance In this review, we discuss the identified metabolic changes in MM and the BM microenvironment and summarize how these identified changes have been targeted (by inhibitors, genetic approaches or deprivation studies) in order to block MM progression and survival.

Topical administration of pterostilbene accelerates burn wound healing in diabetes through activation of the HIF1α signaling pathway

Impaired wound healing is one of a variety of severe diabetic complications and involves many factors, including consistent oxidative stress, prolonged inflammation, impaired angiogenesis, and delayed re-epithelialization. Despite the severe negative impacts that impaired wound healing has on patients' lives, detailed mechanisms and effective therapies are still not fully developed. In this study, we aim to investigate the potential effects and mechanisms of topical administration of pterostilbene and resveratrol on burn wound healing in diabetes. Our in vitro experiments in human umbilical vein endothelial cells showed that long term exposure of hyperglycemia induces oxidative stress and suppression of hypoxia inducible factor1α (HIF1α) signaling pathway, and pterostilbene treatment completely, while resveratrol treatment partly, reversed this effect. Further in vivo experiments in diabetic rats showed that topical administration of pterostilbene exhibited stronger efficacy than resveratrol in normalizing oxidative stress, HIF1α activity, and accelerating burn wound healing in diabetes. We conclude that topical administration of pterostilbene accelerates burn wound healing in diabetes through activation of the HIF1α signaling pathway; thus, pterostilbene may be a potential candidate for clinical treatment of burn wound healing in diabetes.

FOXM1 regulates glycolysis and energy production in multiple myeloma

The transcription factor, forkhead box M1 (FOXM1), has been implicated in the natural history and outcome of newly diagnosed high-risk myeloma (HRMM) and relapsed/refractory myeloma (RRMM), but the mechanism with which FOXM1 promotes the growth of neoplastic plasma cells is poorly understood. Here we show that FOXM1 is a positive regulator of myeloma metabolism that greatly impacts the bioenergetic pathways of glycolysis and oxidative phosphorylation (OxPhos). Using FOXM1-deficient myeloma cells as principal experimental model system, we find that FOXM1 increases glucose uptake, lactate output, and oxygen consumption in myeloma. We demonstrate that the novel 1,1-diarylethylene small-compound FOXM1 inhibitor, NB73, suppresses myeloma in cell culture and human-in-mouse xenografts using a mechanism that includes enhanced proteasomal FOXM1 degradation. Consistent with the FOXM1-stabilizing chaperone function of heat shock protein 90 (HSP90), the HSP90 inhibitor, geldanamycin, collaborates with NB73 in slowing down myeloma. These findings define FOXM1 as a key driver of myeloma metabolism and underscore the feasibility of targeting FOXM1 for new approaches to myeloma therapy and prevention.

Targeting metabolic reprogramming in chronic lymphocytic leukemia

Metabolic reprogramming, fundamentally pivotal in carcinogenesis and progression of cancer, is considered as a promising therapeutic target against tumors. In chronic lymphocytic leukemia (CLL) cells, metabolic abnormalities mediate alternations in proliferation and survival compared with normal B cells. However, the role of metabolic reprogramming is still under investigation in CLL. In this review, the critical metabolic processes of CLL were summarized, particularly glycolysis, lipid metabolism and oxidative phosphorylation. The effects of T cells and stromal cells in the microenvironment on metabolism of CLL were also elucidated. Besides, the metabolic alternation is regulated by some oncogenes and tumor suppressor regulators, especially TP53, MYC and ATM. Thus, the agents targeting metabolic enzymes or signal pathways may impede the progression of CLL. Both the inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) statins and the lipoprotein lipase inhibitor orlistat induce the apoptosis of CLL cells. In addition, a series of oxidative phosphorylation inhibitors play important roles in decreasing the proliferation of CLL cells. We epitomized recent advancements in metabolic reprogramming in CLL and discussed their clinical potentiality for innovative therapy options. Metabolic reprogramming plays a vital role in the initiation and progression of CLL. Therapeutic approaches targeting metabolism have their advantages in improving the survival of CLL patients. This review may shed novel light on the metabolism of CLL, leading to the development of targeted agents based on the reshaping metabolism of CLL cells.

Ivermectin accelerates autophagic death of glioma cells by inhibiting glycolysis through blocking GLUT4 mediated JAK/STAT signaling pathway activation

OBJECTIVE

This study aimed to investigate the regulatory effect of ivermectin (IVM) on energy metabolism in glioma progression, and provide a reference for the treatment of glioma.

METHODS

Glioma cells were treated with IVM to measure cell viability, autophagy marker protein expression, ATP content, glucose uptake, pyruvate content, and expression of key enzymes of glycolysis. Glucose transporter 4 (GLUT4) or siGLUT4 was transfected in IVM treated U87 cells to investigate the effect of GLUT4 on cellular glycolysis and autophagy. The JAK2 inhibitor AZD-1480 was introduced to explore the specific mechanism by which IVM regulates glycolysis and autophagy. Rat models of glioma xenograft were constructed and treated with 10 mg/kg IVM to observe tumor growth and examine the expression levels of GLUT4 and autophagy marker proteins in tumor tissues.

RESULTS

IVM inhibited glioma cell survival and promoted cell death. IVM promoted LC3-II protein expression and inhibited p62/SQSTM1 protein expression in glioma cells. IVM decreased adenosine-triphosphate (ATP) and pyruvate content, promoted glucose uptake, and reduced HK2 and PFK1 protein expression in U87 cells. IVM inhibited GLUT4 protein expression, and overexpression of GLUT4 promoted glycolysis and inhibited autophagic cell death in U87 cells. IVM inhibited glycolysis by blocking GLUT4 mediated the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway activation. IVM inhibited tumor growth in vivo, decreased the protein expression of GLUT4, JAK2, HK2, and PFK1 in tumor tissues, decreased the phosphorylation levels of STAT3/STAT5, and promoted the expression of autophagy marker proteins.

CONCLUSIONS

IVM accelerates autophagic death of glioma cells by inhibiting glycolysis through blocking GLUT4 mediated JAK/STAT signaling pathway activation.

The Mechanism of Warburg Effect-Induced Chemoresistance in Cancer

Although chemotherapy can improve the overall survival and prognosis of cancer patients, chemoresistance remains an obstacle due to the diversity, heterogeneity, and adaptability to environmental alters in clinic. To determine more possibilities for cancer therapy, recent studies have begun to explore changes in the metabolism, especially glycolysis. The Warburg effect is a hallmark of cancer that refers to the preference of cancer cells to metabolize glucose anaerobically rather than aerobically, even under normoxia, which contributes to chemoresistance. However, the association between glycolysis and chemoresistance and molecular mechanisms of glycolysis-induced chemoresistance remains unclear. This review describes the mechanism of glycolysis-induced chemoresistance from the aspects of glycolysis process, signaling pathways, tumor microenvironment, and their interactions. The understanding of how glycolysis induces chemoresistance may provide new molecular targets and concepts for cancer therapy.

Myeloma-Bone Interaction: A Vicious Cycle via TAK1-PIM2 Signaling

Simple Summary

Myeloma cells interact with their ambient cells in the bone, such as bone marrow stromal cells, osteoclasts, and osteocytes, resulting in enhancement of osteoclastogenesis and inhibition of osteoblastogenesis while enhancing their growth and drug resistance. The activation of the TAK1–PIM2 signaling axis appears to be vital for this mutual interaction, posing it as an important therapeutic target to suppress tumor expansion and ameliorate bone destruction in multiple myeloma.

Abstract

Multiple myeloma (MM) has a propensity to develop preferentially in bone and form bone-destructive lesions. MM cells enhance osteoclastogenesis and bone resorption through activation of the RANKL–NF-κB signaling pathway while suppressing bone formation by inhibiting osteoblastogenesis from bone marrow stromal cells (BMSCs) by factors elaborated in the bone marrow and bone in MM, including the soluble Wnt inhibitors DKK-1 and sclerostin, activin A, and TGF-β, resulting in systemic bone destruction with loss of bone. Osteocytes have been drawn attention as multifunctional regulators in bone metabolism. MM cells induce apoptosis in osteocytes to trigger the production of factors, including RANKL, sclerostin, and DKK-1, to further exacerbate bone destruction. Bone lesions developed in MM, in turn, provide microenvironments suited for MM cell growth/survival, including niches to foster MM cells and their precursors. Thus, MM cells alter the microenvironments through bone destruction in the bone where they reside, which in turn potentiates tumor growth and survival, thereby generating a vicious loop between tumor progression and bone destruction. The serine/threonine kinases PIM2 and TAK1, an upstream mediator of PIM2, are overexpressed in bone marrow stromal cells and osteoclasts as well in MM cells in bone lesions. Upregulation of the TAK1–PIM2 pathway plays a critical role in tumor expansion and bone destruction, posing the TAK1–PIM2 pathway as a pivotal therapeutic target in MM.

PPARs and Tumor Microenvironment: The Emerging Roles of the Metabolic Master Regulators in Tumor Stromal-Epithelial Crosstalk and Carcinogenesis

Peroxisome proliferator-activated receptors (PPARs) have been extensively studied for more than three decades. Consisting of three isotypes, PPARα, γ, and β/δ, these nuclear receptors are regarded as the master metabolic regulators which govern many aspects of the body energy homeostasis and cell fate. Their roles in malignancy are also increasingly recognized. With the growing interest in crosstalk between tumor stroma and epithelium, this review aims to highlight the current knowledge on the implications of PPARs in the tumor microenvironment. PPARγ plays a crucial role in the metabolic reprogramming of cancer-associated fibroblasts and adipocytes, coercing the two stromal cells to become substrate donors for cancer growth. Fibroblast PPARβ/δ can modify the risk of tumor initiation and cancer susceptibility. In endothelial cells, PPARβ/δ and PPARα are pro- and anti-angiogenic, respectively. Although the angiogenic role of PPARγ remains ambiguous, it is a crucial regulator in autocrine and paracrine signaling of cancer-associated fibroblasts and tumor-associated macrophages/immune cells. Of note, angiopoietin-like 4 (ANGPTL4), a secretory protein encoded by a target gene of PPARs, triggers critical oncogenic processes such as inflammatory signaling, extracellular matrix derangement, anoikis resistance and metastasis, making it a potential drug target for cancer treatment. To conclude, PPARs in the tumor microenvironment exhibit oncogenic activities which are highly controversial and dependent on many factors such as stromal cell types, cancer types, and oncogenesis stages. Thus, the success of PPAR-based anticancer treatment potentially relies on innovative strategies to modulate PPAR activity in a cell type-specific manner.

Pterostilbene accelerates wound healing by modulating diabetes-induced estrogen receptor β suppression in hematopoietic stem cells

Background

Delayed wound healing is one of the major complications of diabetes mellitus and is characterized by prolonged inflammation, delayed re-epithelialization and consistent oxidative stress, although the detailed mechanism remains unknown. In this study, we aimed to investigate the potential role and effect of pterostilbene (PTE) and hematopoietic stem cells (HSCs) on diabetic wound healing.

Methods

Diabetic rats were used to measure the epigenetic changes in both HSCs and peripheral blood mononuclear cells (PBMCs). A cutaneous burn injury was induced in the rats and PTE-treated diabetic HSCs were transplanted for evaluation of wound healing. In addition, several biomedical parameters, including gene expression, oxidative stress, mitochondrial function and inflammation in macrophages, were also measured.

Results

Our data showed that PTE had a much stronger effect than resveratrol on accelerating diabetic wound healing, likely because PTE can ameliorate diabetes-induced epigenetic changes to estrogen receptor β promoter in HSCs, while resveratrol cannot. Further investigation showed that bone marrow transplantation of PTE-treated diabetic HSCs restores diabetes-induced suppression of estrogen receptor β and its target genes, including nuclear respiratory factor-1 and superoxide dismutase 2, and protects against diabetes-induced oxidative stress, mitochondrial dysfunction and elevated pro-inflammatory cytokines in both PBMCs and macrophages, subsequently accelerating cutaneous wound healing.

Conclusions

HSC may play an important role in wound healing through transferring epigenetic modifications to subsequent PBMCs and macrophages by differentiation, while PTE accelerates diabetic wound healing by modulating diabetes-induced epigenetic changes in HSCs. Thus, PTE may be a novel therapeutic strategy for diabetic wound healing.

Latent Membrane Protein 1 Promotes Tumorigenesis Through Upregulation of PGC1β Signaling Pathway

Natural killer/T-cell lymphoma (NKTCL) is an aggressive Epstein-Barr virus (EBV)-associated non-Hodgkin lymphoma with poor prognosis. In this study, we aimed to investigate the potential mechanism of latent membrane protein 1 (LMP1)-mediated tumorigenesis and provide a novel therapeutic strategy for targeting the EBV DNA genome. We found that LMP1 upregulated the expression of peroxisome proliferator-activated receptor-γ (PPARγ) coactivator-1β (PGC1β) through activation of nuclear factor-κB (NF-κB). Furthermore, the activated PGC1β upregulated the expression of 8-oxoguanine DNA glycosylase (OGG1) through the coactivation of nuclear respiratory factor 1 (NRF1) and GA-binding protein α (GABPα), preventing reactive oxygen species (ROS)-mediated base incision in the EBV genome and favoring its survival. Interruption of hexokinase domain component 1 (HKDC1) by either shRNA or Tf-D-HKC8 peptide suppressed the interaction of HKDC1 with voltage-dependent anion channel 1 (VDAC1), triggering mitochondrial dysfunction and excessive generation of ROS, thus resulting in EBV suppression through ROS-mediated DNA damage. Suppression of the EBV genome inhibited the expression of the LMP1/PGC1β/HKDC1/OGG1 signaling pathway, forming a positive feed forward loop for the generation of ROS, hence inhibiting the EBV genome and subsequent EBV-associated tumor development. We concluded that LMP1 triggers EBV-associated tumorigenesis through activation of the PGC1β pathway. This study provided a novel therapeutic strategy for the treatment of EBV-associated tumors by targeting HKDC1.

Targeting lactate dehydrogenase A (LDHA) exerts antileukemic effects on T-cell acute lymphoblastic leukemia

Background

T‐cell acute lymphoblastic leukemia (T‐ALL) is an uncommon and aggressive subtype of acute lymphoblastic leukemia (ALL). In the serum of T‐ALL patients, the activity of lactate dehydrogenase A (LDHA) is increased. We proposed that targeting LDHA may be a potential strategy to improve T‐ALL outcomes. The current study was conducted to investigate the antileukemic effect of LDHA gene‐targeting treatment on T‐ALL and the underlying molecular mechanism.

Methods

Primary T‐ALL cell lines Jurkat and DU528 were treated with the LDH inhibitor oxamate. MTT, colony formation, apoptosis, and cell cycle assays were performed to investigate the effects of oxamate on T‐ALL cells. Quantitative real‐time PCR (qPCR) and Western blotting analyses were applied to determine the related signaling pathways. A mitochondrial reactive oxygen species (ROS) assay was performed to evaluate ROS production after T‐ALL cells were treated with oxamate. A T‐ALL transgenic zebrafish model with LDHA gene knockdown was established using CRISPR/Cas9 gene‐editing technology, and then TUNEL, Western blotting, and T‐ALL tumor progression analyses were conducted to investigate the effects of LDHA gene knockdown on T‐ALL transgenic zebrafish.

Results

Oxamate significantly inhibited proliferation and induced apoptosis of Jurkat and DU528 cells. It also arrested Jurkat and DU528 cells in G0/G1 phase and stimulated ROS production (all P < 0.001). Blocking LDHA significantly decreased the gene and protein expression of c‐Myc, as well as the levels of phosphorylated serine/threonine kinase (AKT) and glycogen synthase kinase 3 beta (GSK‐3β) in the phosphatidylinositol 3′‐kinase (PI3K) signaling pathway. LDHA gene knockdown delayed disease progression and down‐regulated c‐Myc mRNA and protein expression in T‐ALL transgenic zebrafish.

Conclusion

Targeting LDHA exerted an antileukemic effect on T‐ALL, representing a potential strategy for T‐ALL treatment.

Targeting Multiple Myeloma through the Biology of Long-Lived Plasma Cells

Multiple myeloma (MM) is a hematological malignancy of terminally differentiated bone marrow (BM) resident B lymphocytes known as plasma cells (PC). PC that reside in the bone marrow include a distinct population of long-lived plasma cells (LLPC) that have the capacity to live for very long periods of time (decades in the human population). LLPC biology is critical for understanding MM disease induction and progression because MM shares many of the same extrinsic and intrinsic survival programs as LLPC. Extrinsic survival signals required for LLPC survival include soluble factors and cellular partners in the bone marrow microenvironment. Intrinsic programs that enhance cellular fidelity are also required for LLPC survival including increased autophagy, metabolic fitness, the unfolded protein response (UPR), and enhanced responsiveness to endoplasmic reticulum (ER) stress. Targeting LLPC cell survival mechanisms have led to standard of care treatments for MM including proteasome inhibition (Bortezomib), steroids (Dexamethasone), and immunomodulatory drugs (Lenalidomide). MM patients that relapse often do so by circumventing LLPC survival pathways targeted by treatment. Understanding the mechanisms by which LLPC are able to survive can allow us insight into the treatment of MM, which allows for the enhancement of therapeutic strategies in MM both at diagnosis and upon patient relapse.

Identification of Key Players Involved in CoCl2 Hypoxia Induced Pulmonary Artery Hypertension in vitro

Background

The proliferation of human pulmonary artery smooth muscle cells (HPASMCs) induced by hypoxia was considered as the main cause of pulmonary arterial hypertension (PAH). This study aimed to explore potential genes and long non-coding RNAs (lncRNAs) involved in the mechanism of hypoxia-induced PAH.

Methods

CoCl₂ was utilized to induce hypoxia in HPASMCs, and then cell proliferation, apoptosis, and expression of hypoxia-inducible factors (HIF)-1α were determined. Meanwhile, the RNA isolated from CoCl₂-treated cells and control cells were sequenced and differentially expressed genes/lncRNA (DEGs/DELs) were screened, followed by protein-protein interaction (PPI) construction, functional enrichment analyses, and lncRNA-target prediction. Finally, the expression of key genes and lncRNAs were validated using quantitative real-time PCR and western blotting.

Results

CoCl₂ treatment could significantly increase the expression of HIF-1α and the proliferation of HPASMCs. A total of 360 DEGs and 57 DELs were identified between CoCl₂ treated and control cells. Functional enrichment analysis showed that up-regulated DEGs and DELs’ targets, including LDHA, PFKP, and VEGFA, were significantly enriched in biological processes related to hypoxia or oxygen levels, and the downregulated DEGs and DELs’ targets were significantly enriched in extracellular-matrix-related biological processes. In addition, LDHA, PFKP, and VEGFA exhibited a strong relationship with miR-100HG and TSPEAR-AS2 in lncRNA-target network. The protein level of LDHA, PFKP, and VEGFA were all increased.

Conclusion

LDHA, PFKP, VEGFA, and lncRNA miR-100HG and TSPEAR-AS2 probably played crucial roles in the pathogenesis of CoCl₂ hypoxia-induced-HAP, which might serve as promising therapeutic targets for PAH.

mTOR Regulation of Metabolism in Hematologic Malignancies

Neoplastic cells rewire their metabolism, acquiring a selective advantage over normal cells and a protection from therapeutic agents. The mammalian Target of Rapamycin (mTOR) is a serine/threonine kinase involved in a variety of cellular activities, including the control of metabolic processes. mTOR is hyperactivated in a large number of tumor types, and among them, in many hematologic malignancies. In this article, we summarized the evidence from the literature that describes a central role for mTOR in the acquisition of new metabolic phenotypes for different hematologic malignancies, in concert with other metabolic modulators (AMPK, HIF1α) and microenvironmental stimuli, and shows how these features can be targeted for therapeutic purposes.

Nrf2 Suppression Delays Diabetic Wound Healing Through Sustained Oxidative Stress and Inflammation

Impaired wound healing is one of the major complications of diabetes, involving prolonged inflammation, delayed re-epithelialization, and consistent oxidative stress. The detailed mechanism remains unclear, and there is currently no effective treatment for diabetic wound healing. In this study, we aim to investigate the potential role and effect of nuclear factor erythroid-2–related factor-2 (Nrf2) activation on diabetic wound healing. In vitro experiments in rat macrophages showed that hyperglycemia treatment suppresses Nrf2 activation, resulting in oxidative stress with decreased expression of antioxidant genes, including NAD(P)H:quinone oxidoreductase 1 and heme oxygenase 1, together with increased secretion of proinflammatory cytokines, including interleukin 1β (IL1β), IL6, and monocyte chemoattractant protein-1. Both Nrf2 overexpression and Nrf2 activator dimethyl fumarate (DMF) treatment significantly ameliorated oxidative stress and inflammation. On the other hand, both Nrf2 knockdown or Nrf2 inhibitor ML385 mimicked the effect of diabetes. Further in vivo experiments in rats showed that DMF treatment significantly accelerated wound healing in streptozocin-induced diabetic rats with increased expression of antioxidant enzymes and decreased secretion of proinflammatory cytokines, while Nrf2 inhibitor ML385 mimicked the effect of diabetes. We conclude that Nrf2 activation accelerates impaired wound healing by ameliorating diabetes-mediated oxidative stress and inflammation. This provides a new clinical treatment strategy for diabetic wound healing using Nrf2 activator DMF.

Unappreciated Role of LDHA and LDHB to Control Apoptosis and Autophagy in Tumor Cells

Tumor cells possess a high metabolic plasticity, which drives them to switch on the anaerobic glycolysis and lactate production when challenged by hypoxia. Among the enzymes mediating this plasticity through bidirectional conversion of pyruvate and lactate, the lactate dehydrogenase A (LDHA) and lactate dehydrogenase B (LDHB), are indicated. LDHA has a higher affinity for pyruvate, preferentially converting pyruvate to lactate, and NADH to NAD⁺ in anaerobic conditions, whereas LDHB possess a higher affinity for lactate, preferentially converting lactate to pyruvate, and NAD⁺ to NADH, when oxygen is abundant. Apart from the undisputed role of LDHA and LDHB in tumor cell metabolism and adaptation to unfavorable environmental or cellular conditions, these enzymes participate in the regulation of cell death. This review presents the latest progress made in this area on the roles of LDHA and LDHB in apoptosis and autophagy of tumor cells. Several examples of how LDHA and LDHB impact on these processes, as well as possible molecular mechanisms, will be discussed in this article. The information included in this review points to the legitimacy of modulating LDHA and/or LDHB to target tumor cells in the context of human and veterinary medicine.

PGC1β Regulates Breast Tumor Growth and Metastasis by SREBP1-Mediated HKDC1 Expression

Background: Breast cancer is a very common cancer with significant premature mortality in women. In this study, we show that HKDC1 expression in breast cancer cells is increased significantly. We aim to investigate the detailed mechanism for the regulation of HKDC1 expression and its potential contribution to tumorigenesis.

Methods: Gene expression was evaluated by real time PCR, western blotting, and immunohistochemistry. The mechanism for PGC1β/SREBP1-mediated HKDC1 expression was investigated using luciferase reporter assay, chromatin immunoprecipitation, and siRNA techniques. In addition, HKDC1 was overexpressed or knocked down by lentivirus to evaluate the potential effect on in vitro cell proliferation, glucose uptake, mitochondrial function, apoptosis, and reactive oxygen species (ROS) formation. Furthermore, an in vivo xenograft tumor development study was employed to investigate the effect of HKDC1 on tumor growth and mouse survival.

Results: HKDC1 is highly expressed in both breast cancer cells and clinical tumor tissues. HKDC1 expression is upregulated and co-activated by PGC1β through SREBP1 binding motif on the HKDC1 promoter. HKDC1 is located on the mitochondrial membrane and regulates the permeability transition pore opening by binding with VDAC1, subsequently modulating glucose uptake and cell proliferation. Overexpression of HKDC1 increases while knockdown of HKDC1 decreases in vitro breast cancer cell proliferation and in vivo tumor growth, metastasis, and mouse survival.

Conclusions: PGC1β regulates breast cancer tumor growth and metastasis by SREBP1-mediated HKDC1 expression. This provides a novel therapeutic strategy through targeting the PGC1β/HKDC1 signaling pathway for breast cancer treatment.

A novel 4-gene signature for overall survival prediction in lung adenocarcinoma patients with lymph node metastasis

Background

Lung adenocarcinoma (LUAD) patients experiencing lymph node metastasis (LNM) always exhibit poor clinical outcomes. A biomarker or gene signature that could predict survival in these patients would have a substantial clinical impact, allowing for earlier detection of mortality risk and for individualized therapy.

Methods

With the aim to identify a novel mRNA signature associated with overall survival, we analysed LUAD patients with LNM extracted from The Cancer Genome Atlas (TCGA). LASSO Cox regression was applied to build the prediction model. An external cohort was applied to validate the prediction model.

Results

We identified a 4-gene signature that could effectively stratify a high-risk subset of these patients, and time-dependent receiver operating characteristic (tROC) analysis indicated that the signature had a powerful predictive ability. Gene Set Enrichment Analysis (GSEA) showed that the high-risk subset was mainly associated with important cancer-related hallmarks. Moreover, a predictive nomogram was established based on the signature integrated with clinicopathological features. Lastly, the signature was validated by an external cohort from Gene Expression Omnibus (GEO).

Conclusion

In summary, we developed a robust mRNA signature as an independent factor to effectively classify LUAD patients with LNM into low- and high-risk groups, which might provide a basis for personalized treatments for these patients.

Metabolic alterations and the potential for targeting metabolic pathways in the treatment of multiple myeloma

Metabolism is defined as the collection of complex biochemical processes that living cells use to generate energy and maintain their growth and survival. Metabolism encompasses the synthesis and breakdown of glucose, fatty acids, and amino acids; the generation of energy (ATP); and oxidative phosphorylation. In cancer cells, metabolism can be commandeered to promote tumor growth and cellular proliferation. These alterations in metabolism have emerged as an additional hallmark of various cancers. In this review we focus on metabolic alterations in multiple myeloma (MM) - a malignancy of plasma cells - including derangements in glycolysis, gluconeogenesis, the tricarboxylic acid cycle, oxidative phosphorylation, and fatty acid/amino acid synthesis and degradation. Particular focus is given to metabolic alterations that contribute to myeloma cell growth, proliferation and drug resistance. Finally, novel approaches that target metabolic pathways for the treatment of MM are discussed.

Lactate accelerates calcification in VSMCs through suppression of BNIP3-mediated mitophagy

Arterial media calcification is one of the major complications of diabetes mellitus, which is related to oxidative stress and apoptosis. Mitophagy is a special regulation of mitochondrial homeostasis and takes control of intracellular ROS generation and apoptotic pathways. High circulating levels of lactate usually accompanies diabetes. The potential link between lactate, mitophagy and vascular calcification is investigated in this study. Lactate treatment accelerated VSMC calcification, evaluated by measuring the calcium content, ALP activity, RUNX2, BMP-2 protein levels, and Alizarin red S staining. Lactate exposure caused excessive intracellular ROS generation and VSMC apoptosis. Lactate also impaired mitochondrial function, determined by mPTP opening rate, mitochondrial membrane potential and mitochondrial biogenesis markers. Western blot analysis of LC3-II and p62 and mRFP-GFP-LC3 adenovirus detection for autophagy flux revealed that lactate blocked autophagy flux. LC3-II co-staining with LAMP-1 and autophagosome quantification revealed lactate inhibited autophagy. Furthermore, lactate inhibited mitophagy, which was confirmed by TOMM20 and BNIP3 protein levels, LC3-II colocalization with BNIP3 and TEM assays. In addition, BNIP3-mediated mitophagy played a protective role against VSMC calcification in the presence of lactate. This study suggests that lactate accelerates osteoblastic phenotype transition of VSMC and calcium deposition partly through the BNIP3-mediated mitophagy deficiency induced oxidative stress and apoptosis.