Possible Mitochondria-Associated Enzymatic Role in Non-Hodgkin Lymphoma Residual Disease

MiR-122-5p regulates erastin-induced ferroptosis via CS in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a tumor that occurs in the nasopharynx. Although advances in detection and treatment have improved the prognosis of NPC the treatment of advanced NPC remains challenging. Here, we explored the effect of microRNA (miR)-122-5p on erastin-induced ferroptosis in NPC cells and the role of ferroptosis in the development of NPC. The effect of miR-122-5p silencing and overexpression and the effect of citrate synthase on erastin-induced lipid peroxidation in NPC cells was analyzed by measuring the amounts of malondialdehyde, Fe2+, glutathione, and reactive oxygen species and the morphological alterations of mitochondria. The malignant biological behavior of NPC cells was examined by cell counting kit-8, EDU, colony formation, Transwell, and wound healing assays. The effects of miR-122-5p on cell proliferation and migration associated with ferroptosis were examined in vivo in a mouse model of NPC generated by subcutaneous injection of NPC cells. We found that erastin induced ferroptosis in NPC cells. miR-122-5p overexpression inhibited CS, thereby promoting erastin-induced ferroptosis in NPC cells and decreasing NPC cell proliferation, migration, and invasion.

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.

Mitochondria and Their Relationship with Common Genetic Abnormalities in Hematologic Malignancies

Hematologic malignancies are known to be associated with numerous cytogenetic and molecular genetic changes. In addition to morphology, immunophenotype, cytochemistry and clinical characteristics, these genetic alterations are typically required to diagnose myeloid, lymphoid, and plasma cell neoplasms. According to the current World Health Organization (WHO) Classification of Tumors of Hematopoietic and Lymphoid Tissues, numerous genetic changes are highlighted, often defining a distinct subtype of a disease, or providing prognostic information. This review highlights how these molecular changes can alter mitochondrial bioenergetics, cell death pathways, mitochondrial dynamics and potentially be related to mitochondrial genetic changes. A better understanding of these processes emphasizes potential novel therapies.

Inhibiting PHGDH with NCT-503 reroutes glucose-derived carbons into the TCA cycle, independently of its on-target effect

The small-molecule inhibitor of phosphoglycerate dehydrogenase, NCT-503, reduces incorporation of glucose-derived carbons into serine in vitro. Here we describe an off-target effect of NCT-503 in neuroblastoma cell lines expressing divergent phosphoglycerate dehydrogenase (PHGDH) levels and single-cell clones with CRISPR-Cas9-directed PHGDH knockout or their respective wildtype controls. NCT-503 treatment strongly reduced synthesis of glucose-derived citrate in all cell models investigated compared to the inactive drug control and independent of PHGDH expression level. Incorporation of glucose-derived carbons entering the TCA cycle via pyruvate carboxylase was enhanced by NCT-503 treatment. The activity of citrate synthase was not altered by NCT-503 treatment. We also detected no change in the thermal stabilisation of citrate synthase in cellular thermal shift assays from NCT-503-treated cells. Thus, the direct cause of the observed off-target effect remains enigmatic. Our findings highlight off-target potential within a metabolic assessment of carbon usage in cells treated with the small-molecule inhibitor, NCT-503.

Metabolomic analysis based on 1H-nuclear magnetic resonance spectroscopy metabolic profiles in tuberculous, malignant and transudative pleural effusion

Pleural effusion is a common clinical manifestation with various causes. Current diagnostic and therapeutic methods have exhibited numerous limitations. By involving the analysis of dynamic changes in low molecular weight catabolites, metabolomics has been widely applied in various types of disease and have provided platforms to distinguish many novel biomarkers. However, to the best of our knowledge, there are few studies regarding the metabolic profiling for pleural effusion. In the current study, 58 pleural effusion samples were collected, among which 20 were malignant pleural effusions, 20 were tuberculous pleural effusions and 18 were transudative pleural effusions. The small molecule metabolite spectrums were obtained by adopting ¹H nuclear magnetic resonance technology, and pattern-recognition multi-variable statistical analysis was used to screen out different metabolites. One-way analysis of variance, and Student-Newman-Keuls and the Kruskal-Wallis test were adopted for statistical analysis. Over 400 metabolites were identified in the untargeted metabolomic analysis and 26 metabolites were identified as significantly different among tuberculous, malignant and transudative pleural effusions. These metabolites were predominantly involved in the metabolic pathways of amino acids metabolism, glycometabolism and lipid metabolism. Statistical analysis revealed that eight metabolites contributed to the distinction between the three groups: Tuberculous, malignant and transudative pleural effusion. In the current study, the feasibility of identifying small molecule biochemical profiles in different types of pleural effusion were investigated reveal novel biological insights into the underlying mechanisms. The results provide specific insights into the biology of tubercular, malignant and transudative pleural effusion and may offer novel strategies for the diagnosis and therapy of associated diseases, including tuberculosis, advanced lung cancer and congestive heart failure.

Citrate synthase expression affects tumor phenotype and drug resistance in human ovarian carcinoma

Citrate synthase (CS), one of the key enzymes in the tricarboxylic acid (TCA) cycle, catalyzes the reaction between oxaloacetic acid and acetyl coenzyme A to generate citrate. Increased CS has been observed in pancreatic cancer. In this study, we found higher CS expression in malignant ovarian tumors and ovarian cancer cell lines compared to benign ovarian tumors and normal human ovarian surface epithelium, respectively. CS knockdown by RNAi could result in the reduction of cell proliferation, and inhibition of invasion and migration of ovarian cancer cells in vitro. The drug resistance was also inhibited possibly through an excision repair cross complementing 1 (ERCC1)-dependent mechanism. Finally, upon CS knockdown we observed significant increase expression of multiple genes, including ISG15, IRF7, CASP7, and DDX58 in SKOV3 and A2780 cells by microarray analysis and real-time PCR. Taken together, these results suggested that CS might represent a potential therapeutic target for ovarian carcinoma.

Succinate dehydrogenase subunit B inhibits the AMPK-HIF-1α pathway in human ovarian cancer in vitro

Background

Ovarian carcinoma is one of the most common gynecological cancers with high mortality rates. Numerous evidences demonstrate that cancer cells undergo metabolic abnormality during tumorigenesis in tumor microenvironment and further facilitate tumor progression. Succinate dehydrogenase (SDH or Complex II) is one of the important enzymes in the tricarboxylic acid (TCA) cycle. Succinate dehydrogenase subunit B (SDHB) gene, which encodes one of the four subunits of SDH, has been recognized as a tumor suppressor. However the role of SDHB in ovarian cancer is still unclear.

Methods

Using the SDHB specific siRNA and overexpression plasmid, the expression of SDHB was silenced and conversely induced in ovarian cancer cell lines SKOV3 and A2780, respectively. The possible role of SDHB in ovarian cancer was investigated in vitro, using proliferation, migration and invasion assays. To explore the mechanism, proliferation and migration related proteins such as Bcl-2, cleaved caspase 3, p-ERK, MMP-2, and p-FAK were examined by western blot. P-P38, p-AMPKα, and HIF-1α were also examined by western blot. CoCl2 was used to induce HIF-1α expression in SKOV3 and A2780 cells.

Results

SDHB silencing promoted cell proliferation, invasion, and migration, but inhibited apoptosis of SKOV3 and A2780 cells. In contrast, overexpression of SDHB inhibited cell proliferation, invasion, migration, and promoted apoptosis in SKOV3 cells. It was observed that up-regulation of Bcl-2 and MMP-2, activation of p-P38, p-ERK, and p-FAK, inhibition of cleaved caspase 3 in SDHB-silenced cells. Meanwhile, decreased Bcl-2 and MMP-2, inhibition of p-P38, p-ERK, and p-FAK, activation of cleaved caspase 3 were shown in SDHB-overexpressed SKOV3 cells. HIF-1α, an essential factor in tumor progression, was up-regulated in SDHB-silenced cells with the activation of p-AMPKα and down-regulated in SDHB-overexpressed cancer cells with the decreased p-AMPKα. And SDHB was proved to be decreased due to upregulation of HIF-1α expression in CoCl2-treated cancer cells.

Conclusions

Our results firstly revealed that SDHB played a key role in cell proliferation, invasion, migration, and apoptosis of human ovarian carcinoma via AMPK-HIF-1α pathway. SDHB-overexpression might be a new approach to inhibit tumor progression in human ovarian carcinoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-014-0115-1) contains supplementary material, which is available to authorized users.

Cantharidin-mediated ultrastructural and biochemical changes in mitochondria lead to apoptosis and necrosis in murine Dalton's lymphoma

Cantharidin, a type of terpenoid, is the blistering agent of blister beetles frequently used in traditional medicine. The isolation and anticancer activity of cantharidin from blister beetles, Mylabris cichorii has been recently reported by us. This study deals with changes in mitochondrial structure and function and understanding their significance in the underlying mechanism(s) in cantharidin-mediated antitumor effects in Dalton's lymphoma (DL) bearing mice. Cantharidin treatment caused the appearance of abnormal mitochondrial features which included roundish mitochondria with thickened membranes, irregularity in cristae, and appearance of small and large size vacuoles in mitochondria of DL cells. Cantharidin treatment resulted in a decrease in mitochondrial reduced glutathione, succinate dehydrogenase activity, mitochondrial membrane potential, and induced apoptosis and necrosis in DL cells. The decrease/release of mitochondrial cytochrome c were also observed after cantharidin treatment. Flow cytometry-based cell cycle analysis showed a time-dependent accumulation of the sub-G0 population of DL cells, thus, confirming the involvement of apoptosis in tumor cells in cantharidin-mediated antitumor activity. These finding signify that the apoptosis induced by cantharidin in DL cells should involve mitochondrial-dependent pathways. It is suggested that these cantharidin-mediated changes in mitochondria may play a crucial role in its antitumor activity.

Effective use of small-interfering RNA to characterize residual B-cell non-Hodgkin lymphoma cells following chemotherapy

BACKGROUND: Children diagnosed with non-Hodgkin lymphoma (NHL) respond well to therapy resulting in relatively good prognosis. The exceptions are those who continue to have minimal residual disease (MRD). MRD NHL cells have been characterized as having increased mitochondrial DNA (mtDNA) copy numbers with increased expression of citrate synthase and isocitrate dehydrogenase. A proof-of-concept was designed to use small-interfering RNA (siRNA) as a tool to elucidate the relationship between citrate synthase and isocitrate dehydrogenase with cancer cell integrity. METHODS: mtDNA copy number and lactate dehydrogenase activities were assessed in chemotherapy-exposed residual NHL cells after introduction of siRNA against citrate synthase and/or isocitrate dehydrogenase expression. RESULTS: There was a significant decrease in lactate production in cells transfected with citrate synthase siRNA (p=0.02). Citrate synthase-silenced cells had decreased mtDNA copy numbers (p=0.03) compared to isocitrate dehydrogenase-silenced cells or combined citrate synthase- and isocitrate dehydrogenase-silenced cells. CONCLUSION: Inhibition of citrate synthase expression in siRNA-treated NHL cells resulted in decreased mtDNA copy numbers and lactate dehydrogenase expression. This observation needs further validation to determine the role of citrate synthase in mtDNA integrity and if citrate synthase siRNA could be a potential therapeutic modality in eradicating residual B-NHL cells.

Cisplatin- and dietary ascorbic acid-mediated changes in the mitochondria of Dalton's lymphoma-bearing mice

Cisplatin treatment caused a significant increase in the life span of ascites Dalton's lymphoma (DL) Tumor-bearing (TB) mice. However, as compared to cisplatin (CP) alone, combination treatment with ascorbic acid plus CP resulted in better therapeutic efficacy against murine DL. Cisplatin treatment of TB mice resulted in the appearance of thickened and irregular arrangement of mitochondrial cristae in the liver, kidney and DL tumor cells. Combination treatment of the hosts with ascorbic acid and CP lessened deformities in the mitochondria of liver and kidney, while in tumor cells, this increased the formation of vacuoles and disruption in mitochondrial cristae. Cisplatin treatment decreased the succinate dehydrogenase (SDH) activity in the mitochondria of kidney and DL cells and combination treatment caused further decrease in SDH activity in kidney and DL cells during 24-48 h of treatment. After CP treatment, the protein content in the mitochondria of these tissues decreased, and during combination treatment, it showed significant improvement. Mitochondrial lipid peroxidation (LPO) increased in these tissues after CP treatment. However, combination treatment significantly decreased mitochondrial LPO in liver and kidney but increased in DL cells. This increase in mitochondrial LPO in DL cells and decrease in liver and kidney could play an important role in the antitumor activity of combination treatment and at the same time reduce CP-induced toxicity in the host. However, further study may be desirable to explore some aspects of the mechanism(s) involved in these changes in mitochondria.

Mitochondrial DNA in residual leukemia cells in cerebrospinal fluid in children with acute lymphoblastic leukemia

This feasibility study was designed to assess the ability to measure mitochondrial DNA (mtDNA) in cerebrospinal fluid (CSF) cells that contributed to minimal disease/persistent or residual disease (MD/PRD) from children with acute lymphoblastic leukemia (ALL). Increase in mtDNA copies in cancer cells has been suggested to play a role in MD/PRD. CSF as well as blood specimens from 6 children were assayed for MD/PRD and mtDNA copy numbers by quantitative real-time polymerase chain reaction. Of 7 MD/PRD-positive specimens, 6 had increased mtDNA copy numbers; while 11 MD/PRD-negative specimens had no increase in mtDNA copy numbers, p < 0.003. This is the first proof-of-concept study to measure mtDNA copy numbers in MD/PRD-positive CSF specimens from children with ALL. Increase of mtDNA copy numbers in MD/PRD childhood ALL cells and its significance as a mechanism for recurrence requires further investigation.

KEYWORDS

Minimal residual disease; Acute lymphoblastic leukemia; Central nervous system; Cerebrospinal fluid; Mitochondria.