Role of hypoxia in Diffuse Large B-cell Lymphoma: Metabolic repression and selective translation of HK2 facilitates development of DLBCL

Cuproptosis-related lncRNA signature as a prognostic tool and therapeutic target in diffuse large B cell lymphoma

Cuproptosis is a newly defined form of programmed cell death that relies on mitochondria respiration. Long noncoding RNAs (lncRNAs) play crucial roles in tumorigenesis and metastasis. However, whether cuproptosis-related lncRNAs are involved in the pathogenesis of diffuse large B cell lymphoma (DLBCL) remains unclear. This study aimed to identify the prognostic signatures of cuproptosis-related lncRNAs in DLBCL and investigate their potential molecular functions. RNA-Seq data and clinical information for DLBCL were collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). Cuproptosis-related lncRNAs were screened out through Pearson correlation analysis. Utilizing univariate Cox, least absolute shrinkage and selection operator (Lasso) and multivariate Cox regression analysis, we identified seven cuproptosis-related lncRNAs and developed a risk prediction model to evaluate its prognostic value across multiple groups. GO and KEGG functional analyses, single-sample GSEA (ssGSEA), and the ESTIMATE algorithm were used to analyze the mechanisms and immune status between the different risk groups. Additionally, drug sensitivity analysis identified drugs with potential efficacy in DLBCL. Finally, the protein-protein interaction (PPI) network were constructed based on the weighted gene co-expression network analysis (WGCNA). We identified a set of seven cuproptosis-related lncRNAs including LINC00294, RNF139-AS1, LINC00654, WWC2-AS2, LINC00661, LINC01165 and LINC01398, based on which we constructed a risk model for DLBCL. The high-risk group was associated with shorter survival time than the low-risk group, and the signature-based risk score demonstrated superior prognostic ability for DLBCL patients compared to traditional clinical features. By analyzing the immune landscapes between two groups, we found that immunosuppressive cell types were significantly increased in high-risk DLBCL group. Moreover, functional enrichment analysis highlighted the association of differentially expressed genes with metabolic, inflammatory and immune-related pathways in DLBCL patients. We also found that the high-risk group showed more sensitivity to vinorelbine and pyrimethamine. A cuproptosis-related lncRNA signature was established to predict the prognosis and provide insights into potential therapeutic strategies for DLBCL patients.

Long non-coding RNA mitophagy and ALK-negative anaplastic lymphoma-associated transcript: a novel regulator of mitophagy in T-cell lymphoma

Long non-coding RNA (lncRNA) are emerging as powerful and versatile regulators of transcriptional programs and distinctive biomarkers of progression of T-cell lymphoma. Their role in the aggressive anaplastic lymphoma kinase-negative (ALK-) subtype of anaplastic large cell lymphoma (ALCL) has been elucidated only in part. Starting from our previously identified ALCL-associated lncRNA signature and performing digital gene expression profiling of a retrospective cohort of ALCL, we defined an 11 lncRNA signature able to discriminate among ALCL subtypes. We selected a not previously characterized lncRNA, MTAAT, with preferential expression in ALK- ALCL, for molecular and functional studies. We demonstrated that lncRNA MTAAT contributes to an aberrant mitochondrial turnover restraining mitophagy and promoting cellular proliferation. Functionally, lncRNA MTAAT acts as a repressor of a set of genes related to mitochondrial quality control via chromatin reorganization. Collectively, our work demonstrates the transcriptional role of lncRNA MTAAT in orchestrating a complex transcriptional program sustaining the progression of ALK- ALCL.

Hypoxia-specific imaging in patients with lymphoma undergoing CAR-T therapy

PURPOSE

Intratumoral hypoxia in non-Hodgkin's Lymphoma (NHL) may interfere with chimeric antigen receptor T-cell (CAR-T) function. We conducted a single-center pilot study (clinicaltrials.gov ID NCT04409314) of [18F]fluoroazomycin arabinoside, a hypoxia-specific radiotracer abbreviated as [18F]FAZA, to assess the feasibility of this positron emission tomography (PET) imaging modality in this population.

METHODS

Patients with relapsed NHL being evaluated for CAR-T therapy received a one-time [18F]FAZA PET scan before pre-CAR-T lymphodepletion. A tumor to mediastinum (T/M) ratio of 1.2 or higher with regard to [18F]FAZA uptake was defined as positive for intratumoral hypoxia. We planned to enroll 30 patients with an interim futility analysis after 16 scans.

RESULTS

Of 16 scanned patients, 3 had no evidence of disease by standard [18F]fluorodeoxyglucose PET imaging before CAR-T therapy. Six patients (38%) had any [18F]FAZA uptake above background. Using a T/M cutoff of 1.20, only one patient (a 68-year-old male with relapsed diffuse large B-cell lymphoma) demonstrated intratumoral hypoxia in an extranodal chest wall lesion (T/M 1.35). Interestingly, of all 16 scanned patients, he was the only patient with progressive disease within 1 month of CAR-T therapy. However, because of our low overall proportion of positive scans, our study was stopped for futility.

CONCLUSIONS

Our pilot study identified low-level [18F]FAZA uptake in a small number of patients with NHL receiving CAR-T therapy. The only patient who met our pre-specified threshold for intratumoral hypoxia was also the only patient with early CAR-T failure. Future plans include exploration of [18F]FAZA in a more selected patient population.

Metabolic Reprogramming and Potential Therapeutic Targets in Lymphoma

Lymphoma is a heterogeneous group of diseases that often require their metabolism program to fulfill the demand of cell proliferation. Features of metabolism in lymphoma cells include high glucose uptake, deregulated expression of enzymes related to glycolysis, dual capacity for glycolytic and oxidative metabolism, elevated glutamine metabolism, and fatty acid synthesis. These aberrant metabolic changes lead to tumorigenesis, disease progression, and resistance to lymphoma chemotherapy. This metabolic reprogramming, including glucose, nucleic acid, fatty acid, and amino acid metabolism, is a dynamic process caused not only by genetic and epigenetic changes, but also by changes in the microenvironment affected by viral infections. Notably, some critical metabolic enzymes and metabolites may play vital roles in lymphomagenesis and progression. Recent studies have uncovered that metabolic pathways might have clinical impacts on the diagnosis, characterization, and treatment of lymphoma subtypes. However, determining the clinical relevance of biomarkers and therapeutic targets related to lymphoma metabolism is still challenging. In this review, we systematically summarize current studies on metabolism reprogramming in lymphoma, and we mainly focus on disorders of glucose, amino acids, and lipid metabolisms, as well as dysregulation of molecules in metabolic pathways, oncometabolites, and potential metabolic biomarkers. We then discuss strategies directly or indirectly for those potential therapeutic targets. Finally, we prospect the future directions of lymphoma treatment on metabolic reprogramming.

Metabolomics: A New Era in the Diagnosis or Prognosis of B-Cell Non-Hodgkin's Lymphoma

A wide range of histological as well as clinical properties are exhibited by B-cell non-Hodgkin's lymphomas. These properties could make the diagnostics process complicated. The diagnosis of lymphomas at an initial stage is essential because early remedial actions taken against destructive subtypes are commonly deliberated as successful and restorative. Therefore, better protective action is needed to improve the condition of those patients who are extensively affected by cancer when diagnosed for the first time. The development of new and efficient methods for early detection of cancer has become crucial nowadays. Biomarkers are urgently needed for diagnosing B-cell non-Hodgkin's lymphoma and assessing the severity of the disease and its prognosis. New possibilities are now open for diagnosing cancer with the help of metabolomics. The study of all the metabolites synthesised in the human body is called "metabolomics." A patient's phenotype is directly linked with metabolomics, which can help in providing some clinically beneficial biomarkers and is applied in the diagnostics of B-cell non-Hodgkin's lymphoma. In cancer research, it can analyse the cancerous metabolome to identify the metabolic biomarkers. This review provides an understanding of B-cell non-Hodgkin's lymphoma metabolism and its applications in medical diagnostics. A description of the workflow based on metabolomics is also provided, along with the benefits and drawbacks of various techniques. The use of predictive metabolic biomarkers for the diagnosis and prognosis of B-cell non-Hodgkin's lymphoma is also explored. Thus, we can say that abnormalities related to metabolic processes can occur in a vast range of B-cell non-Hodgkin's lymphomas. The metabolic biomarkers could only be discovered and identified as innovative therapeutic objects if we explored and researched them. In the near future, the innovations involving metabolomics could prove fruitful for predicting outcomes and bringing out novel remedial approaches.

HIF-1α mediates CXCR4 transcription to activate the AKT/mTOR signaling pathway and augment the viability and migration of activated B cell-like diffuse large B-cell lymphoma cells

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy with a high relapse rate. We previously found that C-X-C motif chemokine receptor 4 (CXCR4) was highly expressed in DLBCL and associated with poor prognosis. This study focused on the effect of hypoxia-inducible factor-1α (HIF-1α) on CXCR4 expression and the DLBCL progression. Two activated B cell-like DLBCL cell lines Ly-3 and SUDHL2 were transfected with overexpression and knockdown plasmids or HIF-1α. The viability and migration of DLBCL cells were significantly increased under hypoxic conditions, or upon HIF-1α overexpression under normoxic conditions, but the HIF-1α downregulation led to inverse trends. However, the promoting effects of HIF-1α overexpression on DLBCL cells were suppressed by Plerixafor (a CXCR4 inhibitor). The luciferase and chromatin immunoprecipitation assays revealed that HIF-1α bound to the functional site HRE1 on CXCR4 promoter to activate its transcription. HIF-1α-mediated CXCR4 activation further led to increased phosphorylation of AKT/mTOR under hypoxic conditions. Taken together, this work reports that HIF-1α promotes viability and migration of activated B cell-like cells under hypoxia, which might involve the transcription of CXCR4 and the activation of the AKT/mTOR pathway. The finding may provide novel lights in the management of DCBCL.

Current Status of Novel Agents for the Treatment of B Cell Malignancies: What's Coming Next?

Resistance to death is one of the hallmarks of human B cell malignancies and often contributes to the lack of a lasting response to today's commonly used treatments. Drug discovery approaches designed to activate the death machinery have generated a large number of inhibitors of anti-apoptotic proteins from the B-cell lymphoma/leukemia 2 family and the B-cell receptor (BCR) signaling pathway. Orally administered small-molecule inhibitors of Bcl-2 protein and BCR partners (e.g., Bruton's tyrosine kinase and phosphatidylinositol-3 kinase) have already been included (as monotherapies or combination therapies) in the standard of care for selected B cell malignancies. Agonistic monoclonal antibodies and their derivatives (antibody-drug conjugates, antibody-radioisotope conjugates, bispecific T cell engagers, and chimeric antigen receptor-modified T cells) targeting tumor-associated antigens (TAAs, such as CD19, CD20, CD22, and CD38) are indicated for treatment (as monotherapies or combination therapies) of patients with B cell tumors. However, given that some patients are either refractory to current therapies or relapse after treatment, novel therapeutic strategies are needed. Here, we review current strategies for managing B cell malignancies, with a focus on the ongoing clinical development of more effective, selective drugs targeting these molecules, as well as other TAAs and signaling proteins. The observed impact of metabolic reprogramming on B cell pathophysiology highlights the promise of targeting metabolic checkpoints in the treatment of these disorders.

Advances in Understanding of Metabolism of B-Cell Lymphoma: Implications for Therapy

There have been significant recent advances in the understanding of the role of metabolism in normal and malignant B-cell biology. Previous research has focused on the role of MYC and mammalian target of rapamycin (mTOR) and how these interact with B-cell receptor signaling and hypoxia to regulate glycolysis, glutaminolysis, oxidative phosphorylation (OXPHOS) and related metabolic pathways in germinal centers. Many of the commonest forms of lymphoma arise from germinal center B-cells, reflecting the physiological attenuation of normal DNA damage checkpoints to facilitate somatic hypermutation of the immunoglobulin genes. As a result, these lymphomas can inherit the metabolic state of their cell-of-origin. There is increasing interest in the potential of targeting metabolic pathways for anti-cancer therapy. Some metabolic inhibitors such as methotrexate have been used to treat lymphoma for decades, with several new agents being recently licensed such as inhibitors of phosphoinositide-3-kinase. Several other inhibitors are in development including those blocking mTOR, glutaminase, OXPHOS and monocarboxylate transporters. In addition, recent work has highlighted the importance of the interaction between diet and cancer, with particular focus on dietary modifications that restrict carbohydrates and specific amino acids. This article will review the current state of this field and discuss future developments.

Hypoxia-related tumor environment correlated with immune infiltration and therapeutic sensitivity in diffuse large B-cell lymphoma

Background: Due to the high heterogeneity of diffuse large B-cell lymphoma (DLBCL), traditional chemotherapy treatment ultimately failed in one-third of the patients. Big challenges existed in finding how to accurately predict prognosis and provide individualized treatment. Hypoxia, although being a key factor in the development and progression of DLBCL, plays its role in DLBCL prognosis, which has yet to be fully explored.

Methods: Data used in the current study were sourced from the Gene Expression Omnibus (GEO) database. DLBCL patients were divided according to different hypoxia-related subtypes based on the expressions of hypoxia-related genes (HRGs) relevant to survival. Differentially expressed genes (DEGs) between subtypes were identified using the limma package. Using univariate Cox regression and least absolute shrinkage and selection operator (LASSO) analyses, the prognostic signature was established to calculate risk scores. The tumor microenvironment (TME) in low- and high-risk groups was evaluated by single-sample gene set enrichment analysis (ssGSEA) and ESTIMATE. The chemotherapeutic sensitivity in two groups was assessed by IC50 values.

Results: DLBCL patients were clustered into two hypoxia-related subtype groups according to different gene survival and expressions associated with increasing oxygen delivery and reducing oxygen consumption, and these two subtype groups were compared. Based on the differential expression, a risk model was established using univariate cox and LASSO regression analyses, FNDC1, ANTXR1, RARRES2, S100A9, and MT1M. The performance of the risk signature in predicting the prognosis of DLBCL patients was validated in the internal and external datasets, as evidenced by receiver operating characteristic (ROC) curves. In addition, we observed significant differences in the tumor microenvironment and chemotherapeutic response between low- and high-risk groups.

Conclusion: Our study developed novel hypoxia-related subtypes in DLBCL and identified five prognostic signatures for DLBCL patients. These findings may enrich our understanding of the role of hypoxia in DLBCL and help improve the treatment of DLBCL patients.

HK2: a potential regulator of osteoarthritis via glycolytic and non-glycolytic pathways

Osteoarthritis (OA) is an age-related chronic degenerative joint disease where the main characteristics include progressive degeneration of cartilage, varying degrees of synovitis, and periarticular osteogenesis. However, the underlying factors involved in OA pathogenesis remain elusive which has resulted in poor clinical treatment effect. Recently, glucose metabolism changes provide a new perspective on the pathogenesis of OA. Under the stimulation of external environment, the metabolic pathway of chondrocytes tends to change from oxidative phosphorylation (OXPHOS) to aerobic glycolysis. Previous studies have demonstrated that glycolysis of synovial tissue is increased in OA. The hexokinase (HK) is the first rate limiting enzyme in aerobic glycolysis, participating and catalyzing the main pathway of glucose utilization. An isoform of HKs, HK2 is considered to be a key regulator of glucose metabolism, promotes the transformation of glycolysis from OXPHOS to aerobic glycolysis. Moreover, the expression level of HK2 in OA synovial tissue (FLS) was higher than that in control group, which indicated the potential therapeutic effect of HK2 in OA. However, there is no summary to help us understand the potential therapeutic role of glucose metabolism in OA. Therefore, this review focuses on the properties of HK2 and existing research concerning HK2 and OA. We also highlight the potential role and mechanism of HK2 in OA.

Plasma Metabolites Forecast Occurrence and Prognosis for Patients With Diffuse Large B-Cell Lymphoma

Background

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin’s lymphoma with considerable heterogeneity and different clinical prognosis. However, plasma metabomics used to forecast occurrence and prognosis of DLBCL are rarely addressed.

Method

A total of 65 volunteers including 22 healthy controls (Ctrl), 25 DLBCL patients newly diagnosed (ND), and 18 DLBCL patients achieving complete remission (CR) were enrolled. A gas chromatography mass spectrometry-based untargeted plasma metabolomics analysis was performed.

Results

Multivariate statistical analysis displayed distinct metabolic features among Crtl, ND, and CR groups. Surprisingly, metabolic profiles of newly diagnosed DLBCL patients undergoing different prognosis showed clear and distinctive clustering. Based on the candidate metabolic biomarkers (glucose and aspartate) and clinical indicators (lymphocyte, red blood count, and hemoglobin), a distinct diagnostic equation was established showing improved diagnostic performance with an area under curve of 0.936. The enrichment of citric acid cycle, deficiency of branched chain amino acid, methionine, and cysteine in newly diagnosed DLBCL patients was closely associated with poor prognosis. In addition, we found that malate and 2-hydroxy-2-methylbutyric acid were positively correlated with the baseline tumor metabolic parameters (metabolically active tumor volume and total lesion glycolysis), and the higher abundance of plasma malate, the poorer survival.

Conclusion

Our preliminary data suggested plasma metabolomics study was informative to characterize the metabolic phenotypes and forecast occurrence and prognosis of DLBCL. Malate was identified as an unfavorable metabolic biomarker for prognosis-prediction of DLBCL, which provided a new insight on risk-stratification and therapeutic targets of DLBCL. More studies to confirm these associations and investigate potential mechanisms are in the process.

Identification and Validation of a Prognostic Prediction Model in Diffuse Large B-Cell Lymphoma

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous group with varied pathophysiological, genetic, and clinical features, accounting for approximately one-third of all lymphoma cases worldwide. Notwithstanding that unprecedented scientific progress has been achieved over the years, the survival of DLBCL patients remains low, emphasizing the need to develop novel prognostic biomarkers for early risk stratification and treatment optimization.

METHOD

In this study, we screened genes related to the overall survival (OS) of DLBCL patients in datasets GSE117556, GSE10846, and GSE31312 using univariate Cox analysis. Survival-related genes among the three datasets were screened according to the criteria: hazard ratio (HR) >1 or <1 and p-value <0.01. Least Absolute Shrinkage and Selection Operator (LASSO) and multivariate Cox regression analysis were used to optimize and establish the final gene risk prediction model. The TCGA-NCICCR datasets and our clinical cohort were used to validate the performance of the prediction model. CIBERSORT and ssGSEA algorithms were used to estimate immune scores in the high- and low-risk groups.

RESULTS

We constructed an eight-gene prognostic signature that could reliably predict the clinical outcome in training, testing, and validation cohorts. Our prognostic signature also performed distinguished areas under the ROC curve in each dataset, respectively. After stratification based on clinical characteristics such as cell-of-origin (COO), age, eastern cooperative oncology group (ECOG) performance status, international prognostic index (IPI), stage, and MYC/BCL2 expression, the difference in OS between the high- and low-risk groups was statistically significant. Next, univariate and multivariate analyses revealed that the risk score model had a significant prediction value. Finally, a nomogram was established to visualize the prediction model. Of note, we found that the low-risk group was enriched with immune cells.

CONCLUSION

In summary, we identified an eight-gene prognostic prediction model that can effectively predict survival outcomes of patients with DLBCL and built a nomogram to visualize the perdition model. We also explored immune alterations between high- and low-risk groups.

piRNA-30473 contributes to tumorigenesis and poor prognosis by regulating m6A RNA methylation in DLBCL

The initiation and progression of diffuse large B-cell lymphoma (DLBCL) is governed by genetic and epigenetic aberrations. As the most abundant eukaryotic messenger RNA (mRNA) modification, N6-methyladenosine (m6A) is known to influence various fundamental bioprocesses by regulating the target gene; however, the function of m6A modifications in DLBCL is unclear. PIWI-interacting RNAs (piRNAs) have been indicated to be epigenetic effectors in cancer. Here, we show that high expression of piRNA-30473 supports the aggressive phenotype of DLBCL, and piRNA-30473 depletion decreases proliferation and induces cell cycle arrest in DLBCL cells. In xenograft DLBCL models, piRNA-30473 inhibition reduces tumor growth. Moreover, piRNA-30473 is significantly associated with overall survival in a univariate analysis and is statistically significant after adjusting for the National Comprehensive Cancer Network-International Prognostic Index in the multivariate analysis. Additional studies demonstrate that piRNA-30473 exerts its oncogenic role through a mechanism involving the upregulation of WTAP, an m6A mRNA methylase, and thus enhances the global m6A level. Integrating transcriptome and m6A-sequencing analyses reveals that WTAP increases the expression of its critical target gene, hexokinase 2 (HK2), by enhancing the HK2 m6A level, thereby promoting the progression of DLBCL. Together, the piRNA-30473/WTAP/HK2 axis contributes to tumorigenesis by regulating m6A RNA methylation in DLBCL. Furthermore, by comprehensively analyzing our clinical data and data sets, we discover that the m6A regulatory genes piRNA-30473 and WTAP improve survival prediction in DLBCL patients. Our study highlights the functional importance of the m6A modification in DLBCL and might assist in the development of a prognostic stratification and therapeutic approach for DLBCL.

Targeting the tumor microenvironment in B-cell lymphoma: challenges and opportunities

B-cell lymphoma is a group of hematological malignancies with high clinical and biological heterogeneity. The pathogenesis of B-cell lymphoma involves a complex interaction between tumor cells and the tumor microenvironment (TME), which is composed of stromal cells and extracellular matrix. Although the roles of the TME have not been fully elucidated, accumulating evidence implies that TME is closely relevant to the origination, invasion and metastasis of B-cell lymphoma. Explorations of the TME provide distinctive insights for cancer therapy. Here, we epitomize the recent advances of TME in B-cell lymphoma and discuss its function in tumor progression and immune escape. In addition, the potential clinical value of targeting TME in B-cell lymphoma is highlighted, which is expected to pave the way for novel therapeutic strategies.

Proteomic-Based Analysis of Hypoxia- and Physioxia-Responsive Proteins and Pathways in Diffuse Large B-Cell Lymphoma

Hypoxia is a common feature in most tumors, including hematological malignancies. There is a lack of studies on hypoxia- and physioxia-induced global proteome changes in lymphoma. Here, we sought to explore how the proteome of diffuse large B-cell lymphoma (DLBCL) changes when cells are exposed to acute hypoxic stress (1% of O₂) and physioxia (5% of O₂) for a long-time. A total of 8239 proteins were identified by LC–MS/MS, of which 718, 513, and 486 had significant changes, in abundance, in the Ri-1, U2904, and U2932 cell lines, respectively. We observed that changes in B-NHL proteome profiles induced by hypoxia and physioxia were quantitatively similar in each cell line; however, differentially abundant proteins (DAPs) were specific to a certain cell line. A significant downregulation of several ribosome proteins indicated a translational inhibition of new ribosome protein synthesis in hypoxia, what was confirmed in a pathway enrichment analysis. In addition, downregulated proteins highlighted the altered cell cycle, metabolism, and interferon signaling. As expected, the enrichment of upregulated proteins revealed terms related to metabolism, HIF1 signaling, and response to oxidative stress. In accordance to our results, physioxia induced weaker changes in the protein abundance when compared to those induced by hypoxia. Our data provide new evidence for understanding mechanisms by which DLBCL cells respond to a variable oxygen level. Furthermore, this study reveals multiple hypoxia-responsive proteins showing an altered abundance in hypoxic and physioxic DLBCL. It remains to be investigated whether changes in the proteomes of DLBCL under normoxia and physioxia have functional consequences on lymphoma development and progression.

Metabolic Swifts Govern Normal and Malignant B Cell Lymphopoiesis

B lymphocytes are an indispensable part of the human immune system. They are the effective mediators of adaptive immunity and memory. To accomplish specificity against an antigen, and to establish the related immunologic memory, B cells differentiate through a complicated and strenuous training program that is characterized by multiple drastic genomic modifications. In order to avoid malignant transformation, these events are tightly regulated by multiple checkpoints, the vast majority of them involving bioenergetic alterations. Despite this stringent control program, B cell malignancies are amongst the top ten most common worldwide. In an effort to better understand malignant pathobiology, in this review, we summarize the metabolic swifts that govern normal B cell lymphopoiesis. We also review the existent knowledge regarding malignant metabolism as a means to unravel new research goals and/or therapeutic targets.

Hexokinase 2 in Cancer: A Prima Donna Playing Multiple Characters

Hexokinases are a family of ubiquitous exose-phosphorylating enzymes that prime glucose for intracellular utilization. Hexokinase 2 (HK2) is the most active isozyme of the family, mainly expressed in insulin-sensitive tissues. HK2 induction in most neoplastic cells contributes to their metabolic rewiring towards aerobic glycolysis, and its genetic ablation inhibits malignant growth in mouse models. HK2 can dock to mitochondria, where it performs additional functions in autophagy regulation and cell death inhibition that are independent of its enzymatic activity. The recent definition of HK2 localization to contact points between mitochondria and endoplasmic reticulum called Mitochondria Associated Membranes (MAMs) has unveiled a novel HK2 role in regulating intracellular Ca²⁺ fluxes. Here, we propose that HK2 localization in MAMs of tumor cells is key in sustaining neoplastic progression, as it acts as an intersection node between metabolic and survival pathways. Disrupting these functions by targeting HK2 subcellular localization can constitute a promising anti-tumor strategy.

Mitochondrial Bioenergetics at the Onset of Drug Resistance in Hematological Malignancies: An Overview

The combined derangements in mitochondria network, function and dynamics can affect metabolism and ATP production, redox homeostasis and apoptosis triggering, contributing to cancer development in many different complex ways. In hematological malignancies, there is a strong relationship between cellular metabolism, mitochondrial bioenergetics, interconnections with supportive microenvironment and drug resistance. Lymphoma and chronic lymphocytic leukemia cells, e.g., adapt to intrinsic oxidative stress by increasing mitochondrial biogenesis. In other hematological disorders such as myeloma, on the contrary, bioenergetics changes, associated to increased mitochondrial fitness, derive from the adaptive response to drug-induced stress. In the bone marrow niche, a reverse Warburg effect has been recently described, consisting in metabolic changes occurring in stromal cells in the attempt to metabolically support adjacent cancer cells. Moreover, a physiological dynamic, based on mitochondria transfer, between tumor cells and their supporting stromal microenvironment has been described to sustain oxidative stress associated to proteostasis maintenance in multiple myeloma and leukemia. Increased mitochondrial biogenesis of tumor cells associated to acquisition of new mitochondria transferred by mesenchymal stromal cells results in augmented ATP production through increased oxidative phosphorylation (OX-PHOS), higher drug resistance, and resurgence after treatment. Accordingly, targeting mitochondrial biogenesis, electron transfer, mitochondrial DNA replication, or mitochondrial fatty acid transport increases therapy efficacy. In this review, we summarize selected examples of the mitochondrial derangements in hematological malignancies, which provide metabolic adaptation and apoptosis resistance, also supported by the crosstalk with tumor microenvironment. This field promises a rational design to improve target-therapy including the metabolic phenotype.

SIRT3, a metabolic target linked to ataxia-telangiectasia mutated (ATM) gene deficiency in diffuse large B-cell lymphoma

Inactivation of Ataxia-telangiectasia mutated (ATM) gene results in an increased risk to develop cancer. We show that ATM deficiency in diffuse large B-cell lymphoma (DLBCL) significantly induce mitochondrial deacetylase sirtuin-3 (SIRT3) activity, disrupted mitochondrial structure, decreased mitochondrial respiration, and compromised TCA flux compared with DLBCL cells expressing wild type (WT)-ATM. This corresponded to enrichment of glutamate receptor and glutamine pathways in ATM deficient background compared to WT-ATM DLBCL cells. ATM^−/− DLBCL cells have decreased apoptosis in contrast to radiosensitive non-cancerous A-T cells. In vivo studies using gain and loss of SIRT3 expression showed that SIRT3 promotes growth of ATM CRISPR knockout DLBCL xenografts compared to wild-type ATM control xenografts. Importantly, screening of DLBCL patient samples identified SIRT3 as a putative therapeutic target, and validated an inverse relationship between ATM and SIRT3 expression. Our data predicts SIRT3 as an important therapeutic target for DLBCL patients with ATM null phenotype.

Protein Carbonylation and Lipid Peroxidation in Hematological Malignancies

Among the different mechanisms involved in oxidative stress, protein carbonylation and lipid peroxidation are both important modifications associated with the pathogenesis of several diseases, including cancer. Hematopoietic cells are particularly vulnerable to oxidative damage, as the excessive production of reactive oxygen species and associated lipid peroxidation suppress self-renewal and induce DNA damage and genomic instability, which can trigger malignancy. A richer understanding of the clinical effects of oxidative stress might improve the prognosis of these diseases and inform therapeutic strategies. The most common protein carbonylation and lipid peroxidation compounds, including hydroxynonenal, malondialdehyde, and advanced oxidation protein products, have been investigated for their potential effect on hematopoietic cells in several studies. In this review, we focus on the most important protein carbonylation and lipid peroxidation biomarkers in hematological malignancies, their role in disease development, and potential treatment implications.

ROS systems are a new integrated network for sensing homeostasis and alarming stresses in organelle metabolic processes

Reactive oxygen species (ROS) are critical for the progression of cardiovascular diseases, inflammations and tumors. However, the mechanisms of how ROS sense metabolic stress, regulate metabolic pathways and initiate proliferation, inflammation and cell death responses remain poorly characterized. In this analytic review, we concluded that: 1) Based on different features and functions, eleven types of ROS can be classified into seven functional groups: metabolic stress-sensing, chemical connecting, organelle communication, stress branch-out, inflammasome-activating, dual functions and triple functions ROS. 2) Among the ROS generation systems, mitochondria consume the most amount of oxygen; and nine types of ROS are generated; thus, mitochondrial ROS systems serve as the central hub for connecting ROS with inflammasome activation, trained immunity and immunometabolic pathways. 3) Increased nuclear ROS production significantly promotes cell death in comparison to that in other organelles. Nuclear ROS systems serve as a convergent hub and decision-makers to connect unbearable and alarming metabolic stresses to inflammation and cell death. 4) Balanced ROS levels indicate physiological homeostasis of various metabolic processes in subcellular organelles and cytosol, while imbalanced ROS levels present alarms for pathological organelle stresses in metabolic processes. Based on these analyses, we propose a working model that ROS systems are a new integrated network for sensing homeostasis and alarming stress in metabolic processes in various subcellular organelles. Our model provides novel insights on the roles of the ROS systems in bridging metabolic stress to inflammation, cell death and tumorigenesis; and provide novel therapeutic targets for treating those diseases. (Word count: 246).

Expression of hypoxia-inducible factor 1α, glucose transporter 1, and hexokinase 2 in primary central nervous system lymphoma and the correlation with the biological behaviors

BACKGROUND

It has been indicated that abnormal glucose metabolism mediated by hypoxia-inducible factor 1α (HIF-1α) played an essential role in the development of solid tumor. However, there were rare studies about the role of them in primary central nervous system lymphoma (PCNSL).

OBJECTIVE

To investigate the protein levels of HIF-1α, glucose transporter 1 (GLUT1), and hexokinase 2 (HK2) in PCNSL and whether their levels are associated with prognostic factors.

METHODS

Expression of HIF-1α, GLUT1, and HK2 in 39 tumor tissues was evaluated by immunohistochemical stainning. The correlation of the expression of HIF-1α with the protein level of GLUT1 and HK2 was investigated. In addition, the association between these protein expression levels and clinical parameters and prognosis was analyzed.

RESULTS

In the tumor specimens of PCNSL, positive stainings of HIF-1α, GLUT1, and HK2 were in 23 patients (58.97%), 25 patients (64.1%), and 26 patients (66.67%), respectively, which were associated with the expression level of lactic dehydrogenase (LDH), but not with age, gender, number of lesion, ECOG score, or deep structure. The expression of HIF-1α was positively correlated with the expression of GLUT1 (p < .01, r = .749) and HK2 (p < .01, r = .787). Univariate analysis showed that upregulated GLUT1 was unfavorable predictors of progression-free survival (PFS) in PCNSL. The results of Cox proportional hazards model showed GLUT1 was significantly associated with shorter PFS (hazard ration: 5.65; 95% confidence interval: 1.23-25.84; p = .026).

CONCLUSIONS

This study indicated that there was a hypoxic microenvironment and HIF-1α was involved in the regulation of glycolysis pathway in PCNSL. GLUT1 might be a potential marker for shorter PFS in PCNSL.

Cyclin D1 targets hexokinase 2 to control aerobic glycolysis in myeloma cells

Cancer cells are characterized by the Warburg effect, a shift from mitochondrial respiration to oxidative glycolysis. We report here the crucial role of cyclin D1 in promoting this effect in a cyclin-dependent kinase (CDK)4/6-independent manner in multiple myeloma (MM) cells. We show that the cyclin D1 oncoprotein targets hexokinase 2 (HK2), a major glycolysis regulator, through two original molecular mechanisms in the cytoplasmic and nuclear compartments. In the cytoplasm, cyclin D1 binds HK2 at the outer mitochondrial membrane, and in the nucleus, it binds hypoxia-inducible factor-1α (HIF1α), which regulates HK2 gene transcription. We also show that high levels of HK2 expression are correlated with shorter event-free survival (EFS) and overall survival (OS) in MM patients. HK2 may therefore be considered as a possible target for antimyeloma therapy.

Hexokinase 2 displacement from mitochondria-associated membranes prompts Ca2+ -dependent death of cancer cells

Cancer cells undergo changes in metabolic and survival pathways that increase their malignancy. Isoform 2 of the glycolytic enzyme hexokinase (HK2) enhances both glucose metabolism and resistance to death stimuli in many neoplastic cell types. Here, we observe that HK2 locates at mitochondria‐endoplasmic reticulum (ER) contact sites called MAMs (mitochondria‐associated membranes). HK2 displacement from MAMs with a selective peptide triggers mitochondrial Ca²⁺ overload caused by Ca²⁺ release from ER via inositol‐3‐phosphate receptors (IP3Rs) and by Ca²⁺ entry through plasma membrane. This results in Ca²⁺‐dependent calpain activation, mitochondrial depolarization and cell death. The HK2‐targeting peptide causes massive death of chronic lymphocytic leukemia B cells freshly isolated from patients, and an actionable form of the peptide reduces growth of breast and colon cancer cells allografted in mice without noxious effects on healthy tissues. These results identify a signaling pathway primed by HK2 displacement from MAMs that can be activated as anti‐neoplastic strategy.

Biosystem Analysis of the Hypoxia Inducible Domain Family Member 2A: Implications in Cancer Biology

The expression of HIGD2A is dependent on oxygen levels, glucose concentration, and cell cycle progression. This gene encodes for protein HIG2A, found in mitochondria and the nucleus, promoting cell survival in hypoxic conditions. The genomic location of HIGD2A is in chromosome 5q35.2, where several chromosomal abnormalities are related to numerous cancers. The analysis of high definition expression profiles of HIGD2A suggests a role for HIG2A in cancer biology. Accordingly, the research objective was to perform a molecular biosystem analysis of HIGD2A aiming to discover HIG2A implications in cancer biology. For this purpose, public databases such as SWISS-MODEL protein structure homology-modelling server, Catalogue of Somatic Mutations in Cancer (COSMIC), Gene Expression Omnibus (GEO), MethHC: a database of DNA methylation and gene expression in human cancer, and microRNA-target interactions database (miRTarBase) were accessed. We also evaluated, by using Real-Time Quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR), the expression of Higd2a gene in healthy bone marrow-liver-spleen tissues of mice after quercetin (50 mg/kg) treatment. Thus, among the structural features of HIG2A protein that may participate in HIG2A translocation to the nucleus are an importin α-dependent nuclear localization signal (NLS), a motif of DNA binding residues and a probable SUMOylating residue. HIGD2A gene is not implicated in cancer via mutation. In addition, DNA methylation and mRNA expression of HIGD2A gene present significant alterations in several cancers; HIGD2A gene showed significant higher expression in Diffuse Large B-cell Lymphoma (DLBCL). Hypoxic tissues characterize the “bone marrow-liver-spleen” DLBCL type. The relative quantification, by using qRT-PCR, showed that Higd2a expression is higher in bone marrow than in the liver or spleen. In addition, it was observed that quercetin modulated the expression of Higd2a gene in mice. As an assembly factor of mitochondrial respirasomes, HIG2A might be unexpectedly involved in the change of cellular energetics happening in cancer. As a result, it is worth continuing to explore the role of HIGD2A in cancer biology.

The potential role of glycogen metabolism in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a common and aggressive form of non-Hodgkin lymphoma that may become refractory to available standard therapies, resulting in the need for the development of novel therapeutic targets. Increased metabolic activity of DLBCL tumor cells associated with high expression of glycolysis related proteins, such as glucose transporters and hexokinases, have already been described and indicates a pivotal role for glucose and glycogen metabolism in the malignant progression of the disease. Moreover, several enzymes involved in glycolysis and glycogen metabolism, including hexokinases and glycogen synthase kinase-3, are key molecules in mediating cell survival signaling, indicating that glucose/glycogen metabolism is tightly linked to the cell survival and can potentially be targeted for therapeutic purposes in DLBCL. In this review, we provide a summary of glycogen and glucose metabolism and discuss their significance in the metabolic reprograming that leads to cell survival and proliferation in DLBCL.

Sustain, Adapt, and Overcome-Hypoxia Associated Changes in the Progression of Lymphatic Neoplasia

Irregular perfusion and related tissue hypoxia is a common feature of solid tumors the role of which in the survival and progression cancer has been gradually recognized. Adaptation and selection mechanisms in hypoxic areas in solid tumors are regulated by Hypoxia Inducible transcriptional factor 1 (HIF1) and other hypoxia mediators and are associated with aggressive clinical behavior in a large spectrum of malignancies. Aggressive forms of lymphatic neoplasias present with solid tumor-like features, also including rapid cell growth, necrosis and angiogenesis, the clinical potential of which is still underestimated. While the role of regional hypoxia in normal B-cell maturation and malignant transformation is becoming evident, the impact of tissue hypoxia on their behavior is not well-understood. Compared to some of the common solid cancer types data for some of the key regulators, such as HIF1 and HIF2, and for their downstream effectors are available in a limited fashion. In the current review we aim to overview the physiological aspects of major hypoxia pathways during B-cell maturation and adaptation-related changes reported in lymphatic neoplasia covering important targets, such as carbonic anhydrases IX and XII (CAIX, CAXII), glucose transporter 1 (GLUT-1) and vascular endothelial growth factor (VEGF). In conclusion, experimental and clinical results direct to important but currently unexploited role of hypoxia-driven resistance mechanisms especially in aggressive forms of B-cell neoplasia.

Inhibition of hexokinases holds potential as treatment strategy for rheumatoid arthritis

Introduction

Abnormal glycolytic metabolism contributes to joint inflammation and destruction in rheumatoid arthritis (RA). We examine the expression and function of hexokinases in RA and evaluate the potential of their specific inhibitor for clinical treatment.

Methods

Detection of HKs was assessed in synovial tissue by immunohistology and Western blot. SiRNA and a specific hexokinases inhibitor, lonidamine (LND), were used to evaluate the role of hexokinase-I/II (HK-I/II). Pro-inflammatory and glycolysis factors, cell viability, and apoptosis were assessed by ELISA, RT-qPCR, MTS, and flow cytometry. The clinical effects of LND on type II collagen-induced arthritis (CIA) in DBA-/1 mouse model was evaluated by scoring their clinical responses, synovitis, and cartilage destructions, and ELISA was employed to analyze the concentrations of antibody in the serum of CIA model.

Results

HK-I/II expression and their activities increased in the synovium of RA compared with osteoarthritis (OA). Silencing HK-I/II (siHK-I/II) or LND treatment decreased the production of pro-inflammatory factors, such as IL-6, IL-8, CXCL9, CXCL10, and CXCL11, and cell viability, but induced cell apoptosis of RASFs. The expression of TNF-α and IL-1β of macrophage in response to LPS stimulation were depressed as well after treatment with siHK-I/II or LND. Furthermore, leucocyte infiltration co-cultured with RASFs was also suppressed after inhibiting the expression or activity of HK-I/II. These anti-inflammatory effects overlapped with their anti-glycolytic activities. Treatment with LND in mice with CIA decreased the production of antibodies against IgG1, IgG2a, and IgG2b and consequently attenuated joint inflammation and destruction.

Conclusions

HK-I/II contribute to shape the inflammatory phenotype of RASFs and macrophages. LND may be a potential drug in treating patients with RA.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1865-3) contains supplementary material, which is available to authorized users.

mRNA-to-protein translation in hypoxia

Cells respond to hypoxia by shifting cellular processes from general housekeeping functions to activating specialized hypoxia-response pathways. Oxygen plays an important role in generating ATP to maintain a productive rate of protein synthesis in normoxia. In hypoxia, the rate of the canonical protein synthesis pathway is significantly slowed and impaired due to limited ATP availability, necessitating an alternative mechanism to mediate protein synthesis and facilitate adaptation. Hypoxia adaptation is largely mediated by hypoxia-inducible factors (HIFs). While HIFs are well known for their transcriptional functions, they also play imperative roles in translation to mediate hypoxic protein synthesis. Such adaptations to hypoxia are often hyperactive in solid tumors, contributing to the expression of cancer hallmarks, including treatment resistance. The current literature on protein synthesis in hypoxia is reviewed here, inclusive of hypoxia-specific mRNA selection to translation termination. Current HIF targeting therapies are also discussed as are the opportunities involved with targeting hypoxia specific protein synthesis pathways.

Single Nucleotide Polymorphisms in MIR143 Contribute to Protection Against Non-Hodgkin Lymphoma (NHL) in Caucasian Populations

Recent studies show an association of microRNA (miRNA) polymorphisms (miRSNPs) in different cancer types, including non-Hodgkin lymphoma (NHL). The identification of miRSNPs that are associated with NHL susceptibility may provide biomarkers for early diagnosis and prognosis for patients who may not respond well to current treatment options, including the immunochemotherapy drug combination that includes rituximab, cyclophosphamide, doxorubicin, vincristine and prednisome (R-CHOP). We developed a panel of miRSNPs for genotyping while using multiplex PCR and chip-based mass spectrometry analysis in an Australian NHL case-control population (300 cases, 140 controls). Statistical association with NHL susceptibility was performed while using Chi-square (χ²) and logistic regression analysis. We identified three SNPs in MIR143 that are to be significantly associated with reduced risk of NHL: rs3733846 (odds ratio (OR) [95% confidence interval (CI)] = 0.54 [0.33–0.86], p = 0.010), rs41291957 (OR [95% CI] = 0.61 [0.39–0.94], p = 0.024), and rs17723799 (OR [95% CI] = 0.43 [0.26–0.71], p = 0.0009). One SNP, rs17723799, remained significant after correction for multiple testing (p = 0.015). Subsequently, we investigated an association between the rs17723799 genotype and phenotype by measuring target gene Hexokinase 2 (HKII) expression in cancer cell lines and controls. Our study is the first to report a correlation between miRSNPs in MIR143 and a reduced risk of NHL in Caucasians, and it is supported by significant SNPs in high linkage disequilibrium (LD) in a large European NHL genome wide association study (GWAS) meta-analysis.

Physiological Hypoxia (Physioxia) Impairs the Early Adhesion of Single Lymphoma Cell to Marrow Stromal Cell and Extracellular Matrix. Optical Tweezers Study

Adhesion is critical for the maintenance of cellular structures as well as intercellular communication, and its dysfunction occurs prevalently during cancer progression. Recently, a growing number of studies indicated the ability of oxygen to regulate adhesion molecules expression, however, the influence of physiological hypoxia (physioxia) on cell adhesion remains elusive. Thus, here we aimed: (i) to develop an optical tweezers based assay to precisely evaluate single diffuse large B-cell lymphoma (DLBCL) cell adhesion to neighbor cells (mesenchymal stromal cells) and extracellular matrix (Matrigel) under normoxia and physioxia; and, (ii) to explore the role of integrins in adhesion of single lymphoma cell. We identified the pronouncedly reduced adhesive properties of lymphoma cell lines and primary lymphocytes B under physioxia to both stromal cells and Matrigel. Corresponding effects were shown in bulk adhesion assays. Then we emphasized that impaired β1, β2 integrins, and cadherin-2 expression, studied by confocal microscopy, account for reduction in lymphocyte adhesion in physioxia. Additionally, the blockade studies conducted with anti-integrin antibodies have revealed the critical role of integrins in lymphoma adhesion. To summarize, the presented approach allows for precise confirmation of the changes in single cell adhesion properties provoked by physiological hypoxia. Thus, our findings reveal an unprecedented role of using physiologically relevant oxygen conditioning and single cell adhesion approaches when investigating tumor adhesion in vitro.