Reversal of the glycolytic phenotype of primary effusion lymphoma cells by combined targeting of cellular metabolism and PI3K/Akt/ mTOR signaling

Metabolic Deficiencies Underlie Plasmacytoid Dendritic Cell Exhaustion After Viral Infection

Type I Interferons (IFN-I) are central to host protection against viral infections 1 . While any cell can produce IFN-I, Plasmacytoid Dendritic Cells (pDCs) make greater quantities and more varieties of these cytokines than any other cell type 2 . However, following an initial burst of IFN- I, pDCs lose their exceptional IFN-I production capacity and become "exhausted", a phenotype that associates with enhanced susceptibility to secondary infections 3-5 . Despite this apparent cost for the host, pDC exhaustion is conserved across multiple species and viral infections, but the underlying mechanisms and the potential evolutionary advantages are not well understood. Here we characterize pDC exhaustion and demonstrate that it is associated with a reduced capacity of pDCs to engage both oxidative and glycolytic metabolism. Mechanistically, we identify lactate dehydrogenase B (LDHB) as a novel positive regulator of pDC IFN-I production in mice and humans, show that LDHB deficiency is associated with suppressed IFN-I production, pDC metabolic capacity, and viral control following a viral infection, and demonstrate that preservation of LDHB expression is sufficient to partially restore exhausted pDC function in vitro and in vivo . Furthermore, restoring LDHB in vivo in exhausted pDCs increased IFNAR dependent infection- associated pathology. Therefore, our work identifies a novel and conserved mechanism for balancing immunity and pathology during viral infections, while also providing insight into the highly preserved but previously unexplained phenomenon of pDC exhaustion.

Improved efficacy of quizartinib in combination therapy with PI3K inhibition in primary FLT3-ITD AML cells

Acute myeloid leukemia is a heterogeneous hematopoietic malignancy, characterized by uncontrolled clonal proliferation of abnormal myeloid progenitor cells, with poor outcomes. The internal tandem duplication (ITD) mutation of the Fms-like receptor tyrosine kinase 3 (FLT3) (FLT3-ITD) represents the most common genetic alteration in AML, detected in approximately 30% of AML patients, and is associated with high leukemic burden and poor prognosis. Therefore, this kinase has been regarded as an attractive druggable target for the treatment of FLT3-ITD AML, and selective small molecule inhibitors, such as quizartinib, have been identified and trialled. However, clinical outcomes have been disappointing so far due to poor remission rates, also because of acquired resistance. A strategy to overcome resistance is to combine FLT3 inhibitors with other targeted therapies. In this study, we investigated the preclinical efficacy of the combination of quizartinib with the pan PI3K inhibitor BAY-806946 in FLT3-ITD cell lines and primary cells from AML patients. We show here that BAY-806946 enhanced quizartinib cytotoxicity and, most importantly, that this combination increases the ability of quizartinib to kill CD34+ CD38-leukemia stem cells, whilst sparing normal hematopoietic stem cells. Because constitutively active FLT3 receptor tyrosine kinase is known to boost aberrant PI3K signaling, the increased sensitivity of primary cells to the above combination can be the mechanistic results of the disruption of signaling by vertical inhibition.

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.

Mechanisms Involved in the Promoting Activity of Fibroblasts in HTLV-1-Mediated Lymphomagenesis: Insights into the Plasticity of Lymphomatous Cells

Among the mechanisms leading to progression to Adult T-cell Leukaemia/Lymphoma in Human T-cell Leukaemia Virus type 1 (HTLV-1)-infected subjects, the contribution of stromal components remains poorly understood. To dissect the role of fibroblasts in HTLV-1-mediated lymphomagenesis, transcriptome studies, cytofluorimetric and qRT-PCR analyses of surface and intracellular markers linked to plasticity and stemness in coculture, and in vivo experiments were performed. A transcriptomic comparison between a more lymphomagenic (C91/III) and the parental (C91/PL) cell line evidenced hyperactivation of the PI3K/Akt pathway, confirmed by phospho-ELISA and 2-DE and WB analyses. C91/III cells also showed higher expression of mesenchymal and stemness genes. Short-term coculture with human foreskin fibroblasts (HFF) induced these features in C91/PL cells, and significantly increased not only the cancer stem cells (CSCs)-supporting CD10+GPR77+ HFF subpopulation, but also the percentage of ALDH1bright C91/PL cells. A non-cytotoxic acetylsalicylic acid treatment decreased HFF-induced ALDH1bright C91/PL cells, downregulated mesenchymal and stemness genes in cocultured cells, and delayed lymphoma growth in immunosuppressed mice, thus hindering the supportive activity of HFF on CSCs. These data suggest that crosstalk with HFF significantly intensifies the aggressiveness and plasticity of C91/PL cells, leading to the enrichment in lymphoma-initiating cells. Additional research is needed to better characterize these preliminary findings.

Synergistic cytotoxicity of dual PI3K/mTOR and FLT3 inhibition in FLT3-ITD AML cells

Acute myeloid leukemia (AML) is an aggressive hematopoietic malignancy, characterized by a heterogeneous genetic landscape and complex clonal evolution, with poor outcomes. Mutation at the internal tandem duplication of FLT3 (FLT3-ITD) is one of the most common somatic alterations in AML, associated with high relapse rates and poor survival due to the constitutive activation of the FLT3 receptor tyrosine kinase and its downstream effectors, such as PI3K signaling. Thus, aberrantly activated FLT3-kinase is regarded as an attractive target for therapy for this AML subtype, and a number of small molecule inhibitors of this kinase have been identified, some of which are approved for clinical practice. Nevertheless, acquired resistance to these molecules is often observed, leading to severe clinical outcomes. Therapeutic strategies to tackle resistance include combining FLT3 inhibitors with other antileukemic agents. Here, we report on the preclinical activity of the combination of the FLT3 inhibitor quizartinib with the dual PI3K/mTOR inhibitor PF-04691502 in FLT3-ITD cells. Briefly, we show that the association of these two molecules displays synergistic cytotoxicity in vitro in FLT3-ITD AML cells, triggering 90% cell death at nanomolar concentrations after 48 h.

Cancer cell metabolic plasticity in migration and metastasis

Metabolic reprogramming is a hallmark of cancer metastasis in which cancer cells manipulate their metabolic profile to meet the dynamic energetic requirements of the tumor microenvironment. Though cancer cell proliferation and migration through the extracellular matrix are key steps of cancer progression, they are not necessarily fueled by the same metabolites and energy production pathways. The two main metabolic pathways cancer cells use to derive energy from glucose, glycolysis and oxidative phosphorylation, are preferentially and plastically utilized by cancer cells depending on both their intrinsic metabolic properties and their surrounding environment. Mechanical factors in the microenvironment, such as collagen density, pore size, and alignment, and biochemical factors, such as oxygen and glucose availability, have been shown to influence both cell migration and glucose metabolism. As cancer cells have been identified as preferentially utilizing glycolysis or oxidative phosphorylation based on heterogeneous intrinsic or extrinsic factors, the relationship between cancer cell metabolism and metastatic potential is of recent interest. Here, we review current in vitro and in vivo findings in the context of cancer cell metabolism during migration and metastasis and extrapolate potential clinical applications of this work that could aid in diagnosing and tracking cancer progression in vivo by monitoring metabolism. We also review current progress in the development of a variety of metabolically targeted anti-metastatic drugs, both in clinical trials and approved for distribution, and highlight potential routes for incorporating our recent understanding of metabolic plasticity into therapeutic directions. By further understanding cancer cell energy production pathways and metabolic plasticity, more effective and successful clinical imaging and therapeutics can be developed to diagnose, target, and inhibit metastasis.

Molecular profiling reveals a hypoxia signature in breast implant-associated anaplastic large cell lymphoma

Breast implant-associated anaplastic large cell lymphoma (BIAALCL) is a recently characterized T-cell malignancy that has raised significant patient safety concerns and led to worldwide impact on the implants used and clinical management of patients undergoing reconstructive or cosmetic breast surgery. Molecular signatures distinguishing BIA-ALCL from other anaplastic large cell lymphomas have not been fully elucidated and classification of BIA-ALCL as a World Health Organization entity remains provisional. We performed RNA sequencing and gene set enrichment analysis comparing BIA-ALCL to non-BIAALCL and identified dramatic upregulation of hypoxia signaling genes including the hypoxia-associated biomarker CA9 (carbonic anyhydrase- 9). Immunohistochemistry validated CA9 expression in all BIA-ALCL, with only minimal expression in non-BIA-ALCL. Growth induction in BIA-ALCL-derived cell lines cultured under hypoxic conditions was proportional to upregulation of CA9 expression, and RNA sequencing demonstrated induction of the same gene signature observed in BIAALCL tissue samples compared to non-BIA-ALCL. CA9 silencing blocked hypoxia-induced BIA-ALCL cell growth and cell cycle-associated gene expression, whereas CA9 overexpression in BIA-ALCL cells promoted growth in a xenograft mouse model. Furthermore, CA9 was secreted into BIA-ALCL cell line supernatants and was markedly elevated in human BIA-ALCL seroma samples. Finally, serum CA9 concentrations in mice bearing BIA-ALCL xenografts were significantly elevated compared to those in control serum. Together, these findings characterize BIA-ALCL as a hypoxia-associated neoplasm, likely attributable to the unique microenvironment in which it arises. These data support classification of BIA-ALCL as a distinct entity and uncover opportunities for investigating hypoxia-related proteins such as CA9 as novel biomarkers and therapeutic targets in this disease.

Metabolic heterogeneity and immunocompetence of infiltrating immune cells in the breast cancer microenvironment (Review)

Breast cancer is one of the most common malignancies in women and is characterized by active immunogenicity. Immune cell infiltration plays an important role in the development of breast cancer. The degree of infiltration influences both the response to and effect of treatment. However, immune infiltration is a complex process. Differences in oxygen partial pressure, blood perfusion and nutrients in the tumor microenvironment (TME) suggest that infiltrating immune cells in different sites experience different microenvironments with corresponding changes in the metabolic mode, that is, immune cell metabolism is heterogenous in the TME. Furthermore, the present review found that lipid metabolism can support the immunosuppressive microenvironment in breast cancer based on a review of published literature. Research in this field is still ongoing; however, it is vital to understand the metabolic patterns and effects of different microenvironments for antitumor therapy. Therefore, this review discusses the metabolic responses of various immune cells to different microenvironments in breast cancer and provides potentially meaningful insights for tumor immunotherapy.

Non-Hodgkin Lymphoma Metabolism

Non-Hodgkin lymphomas (NHLs) are a heterogeneous group of lymphoid neoplasms with different biological characteristics. About 90% of all lymphomas in the United States originate from B lymphocytes, while the remaining originate from T cells [1]. The treatment of NHLs depends on the neoplastic histology and stage of the tumor, which will indicate whether radiotherapy, chemotherapy, or a combination is the best suitable treatment [2]. The American Cancer Society describes the staging of lymphoma as follows: Stage I is lymphoma in a single node or area. Stage II is when that lymphoma has spread to another node or organ tissue. Stage III is when it has spread to lymph nodes on two sides of the diaphragm. Stage IV is when cancer has significantly spread to organs outside the lymph system. Radiation therapy is the traditional therapeutic route for localized follicular and mucosa-associated lymphomas. Chemotherapy is utilized for the treatment of large-cell lymphomas and high-grade lymphomas [2]. However, the treatment of indolent lymphomas remains problematic as the patients often have metastasis, for which no standard approach exists [2].

Cancer cell metabolism: Rewiring the mitochondrial hub

To adapt to tumoral environment conditions or even to escape chemotherapy, cells rapidly reprogram their metabolism to handle adversities and survive. Given the rapid rise of studies uncovering novel insights and therapeutic opportunities based on the role of mitochondria in tumor metabolic programing and therapeutics, this review summarizes most significant developments in the field. Taking in mind the key role of mitochondria on carcinogenesis and tumor progression due to their involvement on tumor plasticity, metabolic remodeling, and signaling re-wiring, those organelles are also potential therapeutic targets. Among other topics, we address the recent data intersecting mitochondria as of prognostic value and staging in cancer, by mitochondrial DNA (mtDNA) determination, and current inhibitors developments targeting mtDNA, OXPHOS machinery and metabolic pathways. We contribute for a holistic view of the role of mitochondria metabolism and directed therapeutics to understand tumor metabolism, to circumvent therapy resistance, and to control tumor development.

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.

Development of Novel Irreversible Pyruvate Kinase M2 Inhibitors

As cancer cells undergo metabolic reprogramming in the course of tumorigenesis, targeting energy metabolism represents a promising strategy in cancer therapy. Among various metabolic enzymes examined, pyruvate kinase M2 type (PKM2) has received much attention in light of its multifaceted function in promoting tumor growth and progression. In this study, we reported the development of a novel irreversible inhibitor of PKM2, compound 1, that exhibits a differential tumor-suppressive effect among an array of cancer cell lines. We further used a clickable activity-based protein profiling (ABPP) probe and SILAC coupled with LC-MS/MS to identify the Cys-317 and Cys-326 residues of PKM2 as the covalent binding sites. Equally important, compound 1 at 10 mg/kg was effective in suppressing xenograft tumor growth in nude mice without causing acute toxicity by targeting both metabolic and oncogenic functions. Together, these data suggest its translational potential to foster new strategies for cancer therapy.

Kinome profiling of non-Hodgkin lymphoma identifies Tyro3 as a therapeutic target in primary effusion lymphoma

Non-Hodgkin lymphomas (NHLs) make up the majority of lymphoma diagnoses and represent a very diverse set of malignancies. We sought to identify kinases uniquely up-regulated in different NHL subtypes. Using multiplexed inhibitor bead-mass spectrometry (MIB/MS), we found Tyro3 was uniquely up-regulated and important for cell survival in primary effusion lymphoma (PEL), which is a viral lymphoma infected with Kaposi's sarcoma-associated herpesvirus (KSHV). Tyro3 was also highly expressed in PEL cell lines as well as in primary PEL exudates. Based on this discovery, we developed an inhibitor against Tyro3 named UNC3810A, which hindered cell growth in PEL, but not in other NHL subtypes where Tyro3 was not highly expressed. UNC3810A also significantly inhibited tumor progression in a PEL xenograft mouse model that was not seen in a non-PEL NHL model. Taken together, our data suggest Tyro3 is a therapeutic target for PEL.

PI3K/Akt signaling transduction pathway, erythropoiesis and glycolysis in hypoxia (Review)

The purpose of this review is to summarize the research progress of PI3K/Akt signaling pathway in erythropoiesis and glycolysis. Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) is activated by numerous genes and leads to protein kinase B (Akt) binding to the cell membrane, with the help of phosphoinositide-dependent kinase, in the PI3K/Akt signal transduction pathway. Threonine and serine phosphorylation contribute to Akt translocation from the cytoplasm to the nucleus and further mediates enzymatic biological effects, including those involved in cell proliferation, apoptosis inhibition, cell migration, vesicle transport and cell cancerous transformation. As a key downstream protein of the PI3K/Akt signaling pathway, hypoxia-inducible factor (HIF)-1 is closely associated with the concentration of oxygen in the environment. Maintaining stable levels of HIF-1 protein is critical under normoxic conditions; however, HIF-1 levels quickly increase under hypoxic conditions. HIF-1α is involved in the acute hypoxic response associated with erythropoietin, whereas HIF-2α is associated with the response to chronic hypoxia. Furthermore, PI3K/Akt can reduce the synthesis of glycogen and increase glycolysis. Inhibition of glycogen synthase kinase 3β activity by phosphorylation of its N-terminal serine increases accumulation of cyclin D1, which promotes the cell cycle and improves cell proliferation through the PI3K/Akt signaling pathway. The PI3K/Akt signaling pathway is closely associated with a variety of enzymatic biological effects and glucose metabolism.

Development of solvent-casting particulate leaching (SCPL) polymer scaffolds as improved three-dimensional supports to mimic the bone marrow niche

The need for new approaches to investigate ex vivo the causes and effects of tumor and to achieve improved cancer treatments and medical therapies is particularly urgent for malignant pathologies such as lymphomas and leukemias, whose tissue initiator cells interact with the stroma creating a three-dimensional (3D) protective environment that conventional mono- and bi-dimensional (2D) models are not able to simulate realistically. The solvent-casting particulate leaching (SCPL) technique, that is already a standard method to produce polymer-based scaffolds for bone tissue repair, is proposed here to fabricate innovative 3D porous structures to mimic the bone marrow niche in vitro. Two different polymers, namely a rigid polymethyl methacrylate (PMMA) and a flexible polyurethane (PU), were evaluated to the purpose, whereas NaCl, in the form of common salt table, resulted to be an efficient porogen. The adoption of an appropriate polymer-to-salt ratio, experimentally defined as 1:4 for both PMMA and PU, gave place to a rich and interconnected porosity, ranging between 82.1 vol% and 91.3 vol%, and the choice of admixing fine-grained or coarse-grained salt powders allowed to control the final pore size. The mechanical properties under compression load were affected both by the polymer matrix and by the scaffold's architecture, with values of the elastic modulus indicatively varying between 29 kPa and 1283 kPa. Preliminary tests performed with human stromal HS-5 cells co-cultured with leukemic cells allowed us to conclude that stromal cells grown associated to the supports keep their well-known protective and pro-survival effect on cancer cells, indicating that these devices can be very useful to mimic the bone marrow microenvironment and therefore to assess the efficacy of novel therapies in pre-clinical studies.

Biology and management of primary effusion lymphoma

Primary effusion lymphoma (PEL) is a rare B-cell malignancy that most often occurs in immunocompromised patients, such as HIV-infected individuals and patients receiving organ transplantation. The main characteristic of PEL is neoplastic effusions in body cavities without detectable tumor masses. The onset of the disease is associated with latent infection of human herpes virus 8/Kaposi sarcoma–associated herpes virus, and the normal counterpart of tumor cells is B cells with plasmablastic differentiation. A condition of immunodeficiency and a usual absence of CD20 expression lead to the expectation of the lack of efficacy of anti-CD20 monoclonal antibody; clinical outcomes of the disease remain extremely poor, with an overall survival at 1 year of ∼30%. Although recent progress in antiretroviral therapy has improved outcomes of HIV-infected patients, its benefit is still limited in patients with PEL. Furthermore, the usual high expression of programmed death ligand 1 in tumor cells, one of the most important immune-checkpoint molecules, results in the immune escape of tumor cells from the host immune defense, which could be the underlying mechanism of poor treatment efficacy. Molecular-targeted therapies for the activating pathways in PEL, including NF-κB, JAK/STAT, and phosphatidylinositol 3-kinase/AKT, have emerged to treat this intractable disease. A combination of immunological recovery from immune deficiency, overcoming the immune escape, and the development of more effective drugs will be vital for improving the outcomes of PEL patients in the future.

Epstein-Barr Virus-Induced Metabolic Rearrangements in Human B-Cell Lymphomas

Tumor metabolism has been the object of several studies in the past, leading to the pivotal observation of a consistent shift toward aerobic glycolysis (so-called Warburg effect). More recently, several additional investigations proved that tumor metabolism is profoundly affected during tumorigenesis, including glucose, lipid and amino-acid metabolism. It is noticeable that metabolic reprogramming can represent a suitable therapeutic target in many cancer types. Epstein–Barr virus (EBV) was the first virus linked with cancer in humans when Burkitt lymphoma (BL) was described. Besides other well-known effects, it was recently demonstrated that EBV can induce significant modification in cell metabolism, which may lead or contribute to neoplastic transformation of human cells. Similarly, virus-induced tumorigenesis is characterized by relevant metabolic abnormalities directly induced by the oncoviruses. In this article, the authors critically review the most recent literature concerning EBV-induced metabolism alterations in lymphomas.

Dual inhibition of PI3K/mTOR signaling in chemoresistant AML primary cells

A main cause of treatment failure for AML patients is resistance to chemotherapy. Survival of AML cells may depend on mechanisms that elude conventional drugs action and/or on the presence of leukemia initiating cells at diagnosis, and their persistence after therapy. MDR1 gene is an ATP-dependent drug efflux pump known to be a risk factor for the emergence of resistance, when combined to unstable cytogenetic profile of AML patients. In the present study, we analyzed the sensitivity to conventional chemotherapeutic drugs of 26 samples of primary blasts collected from AML patients at diagnosis. Detection of cell viability and apoptosis allowed to identify two group of samples, one resistant and one sensitive to in vitro treatment. The cells were then analyzed for the presence and the activity of P-glycoprotein. A comparative analysis showed that resistant samples exhibited a high level of MDR1 mRNA as well as of P-glycoprotein content and activity. Moreover, they also displayed high PI3K signaling. Therefore, we checked whether the association with signaling inhibitors might resensitize resistant samples to chemo-drugs. The combination showed a very potent cytotoxic effect, possibly through down modulation of MDR1, which was maintained also when primary blasts were co-cultured with human stromal cells. Remarkably, dual PI3K/mTOR inactivation was cytotoxic also to leukemia initiating cells. All together, our findings indicate that signaling activation profiling associated to gene expression can be very useful to stratify patients and improve therapy.

Non-Hodgkin Lymphoma Metabolism

Non-Hodgkin lymphomas (NHLs) are a heterogeneous group of lymphoid neoplasms with differing biological characteristics. About 90% of all lymphomas in the United States originate from B lymphocytes, while the remaining originate from T cells [1]. The treatment of NHLs depends on neoplastic histology and the stage of the tumor, which will indicate whether radiotherapy, chemotherapy, or a combination is the best suitable treatment [2]. The American Cancer Society describes the staging of lymphoma as follows: Stage I is lymphoma in a single node or area. Stage II is when that lymphoma has spread to another node or organ tissue. Stage III is when it has spread to lymph nodes in two sides of the diaphragm. Stage IV is when the cancer has significantly spread to organs outside the lymph system. Radiation therapy is the traditional therapeutic route for localized follicular and mucosa-associated lymphomas. Chemotherapy is utilized for the treatment of large cell lymphomas and high-grade lymphomas [2]. However, treatment of indolent lymphomas remains problematic as the patients often have metastasis for which no standard approach exists [2].

Ataxia-Telangiectasia Mutated Modulation of Carbon Metabolism in Cancer

The ataxia-telangiectasia mutated (ATM) protein kinase has been extensively studied for its role in the DNA damage response and its association with the disease ataxia telangiectasia. There is increasing evidence that ATM also plays an important role in other cellular processes, including carbon metabolism. Carbon metabolism is highly dysregulated in cancer due to the increased need for cellular biomass. A number of recent studies report a non-canonical role for ATM in the regulation of carbon metabolism. This review highlights what is currently known about ATM's regulation of carbon metabolism, the implication of these pathways in cancer, and the development of ATM inhibitors as therapeutic strategies for cancer.

Propofol promotes apoptosis and suppresses the HOTAIR-mediated mTOR/p70S6K signaling pathway in melanoma cells

Propofol is an intravenous anesthetic, which is widely used in clinical anesthesia induction and maintenance and is critical in the sedation of patients. However, the functions and mechanisms of propofol on apoptosis of melanoma cells remain unclear. The present study investigated whether propofol promotes cell apoptosis and suppresses the HOX transcript antisense RNA (HOTAIR)-mediated mechanistic target of rapamycin (mTOR) pathway in melanoma cells. B16F10 cells were cultured with different concentrations (0-10 µM) of propofol for 24 or 48 h. Proliferation and apoptosis of B16F10 cells were detected using MTT assay and flow cytometry. The pcDNA 3.1(-)-HOTAIR and pcDNA 3.1(-)-control plasmids were transfected into B16F10 cells using Lipofectamine 2000. In the present study, treatment with propofol significantly reduced viability, and induced apoptosis and caspase-3 activity in melanoma cells. Propofol treatment significantly inhibited HOTAIR expression and the expression of phosphorylated (p)-mTOR and p- p70S6K protein in melanoma cells. Overexpression of HOTAIR significantly increased viability of melanoma cells, and increased HOTAIR, p-mTOR and p-p70S6K protein expression in melanoma cells. These results indicated that propofol promotes apoptosis and suppresses the HOTAIR-mediated mTOR signaling pathway in melanoma cells.

STYK1 promotes Warburg effect through PI3K/AKT signaling and predicts a poor prognosis in nasopharyngeal carcinoma

STYK1 (Serine/threonine/tyrosine kinase 1), a member of the receptor tyrosine kinase family, exhibits tumorigenicity in many types of cancers. Our study reveals the important role played by STYK1 in nasopharyngeal carcinoma. STYK1 is upregulated in nasopharyngeal carcinoma tissues compared with para-carcinoma. Knockdown of STYK1 inhibits nasopharyngeal carcinoma cell proliferation, migration, and invasion, while ectopic STYK1 expression significantly promoted cell proliferation, migration, and invasion abilities. In addition, we provided lines of evidence supporting the critical role of STYK1 in the regulation of glycolysis via activation of phosphoinositide 3-kinase/AKT pathway. Survival analysis reveals that STYK1 level is an independent prognostic factor for nasopharyngeal carcinoma patients. Our results indicate that STYK1 is a promising therapeutic target in nasopharyngeal carcinoma.

Regulation of glucose uptake in lymphoma cell lines by c-MYC- and PI3K-dependent signaling pathways and impact of glycolytic pathways on cell viability

BACKGROUND

Changes in glucose and energy metabolism contribute to the altered phenotype of cancer cells and are the basis for positron emission tomography with ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) to visualize tumors in vivo. The molecular background of the enhanced glucose uptake and its regulation in lymphoma cells is not fully clarified and may provide new possibilities to reverse the altered metabolism. Thus in this study we investigated regulation of glucose uptake by different signaling pathways. Furthermore, the effect of the glucose analog 2-deoxy-D-glucose (2-DG) alone and in combination with other inhibitors on cell survival was studied.

METHODS

An FDG uptake assay was established and uptake of FDG by lymphoma cells was determined after incubation with inhibitors of the c-MYC and the PI3K signalling pathways that are known to be activated in lymphoma cells and able to regulate glucose metabolism. Inhibitors of MAPK signalling pathways whose role in altered metabolism is still unclear were also investigated. Expression of mRNAs of the glucose transporter 1 (GLUT1), hexokinase 2 (HK2), glucose-6-phosphatase (G6Pase) and lactate dehydrogenase A (LDHA) and of the glucose metabolism-regulating micro RNAs (miRNA) miR21, -23a, -133a, -133b, -138-1 and -143 was determined by RT-PCR. Cell viability was analysed by MTT assay.

RESULTS

Treatment with the c-MYC inhibitor 10058-F4 and inhibitors of the PI3K/mTOR pathway diminished uptake of FDG in all three cell lines, while inhibition of MAPK pathways had no effect on glucose uptake. Expression of glycolysis-related genes and miRNAs were diminished, although to a variable degree in the three cell lines. The c-MYC inhibitor, the PI3K inhibitor LY294002, the mTOR inhibitor Rapamycin and 2-DG all diminished the number of viable cells. Interestingly, in combination with 2-DG, the c-MYC inhibitor, LY294002 and the p38 MAPK inhibitor SB203580 had synergistic effects on cell viability in all three cell lines.

CONCLUSIONS

c-MYC- and PI3K/mTOR-inhibitors decreased viability of the lymphoma cells and led to decreased glucose uptake, expression of glycolysis-associated genes, and glucose metabolism-regulating miRNAs. Inhibition of HK by 2-DG reduced cell numbers as a single agent and synergistically with inhibitors of other intracellular pathways. Thus, targeted inhibition of the pathways investigated here could be a strategy to suppress the glycolytic phenotype of lymphoma cells and reduce proliferation.

Cross-talk between the CK2 and AKT signaling pathways in cancer

CK2 and AKT display a high degree of cross-regulation of their respective functions, both directly, through physical interaction and phosphorylation, and indirectly, through an intense cross-talk of key downstream effectors, ultimately leading to sustained AKT activation. Being CK2 and AKT attractive targets for therapeutic intervention, here we would like to emphasize how AKT and CK2 might influence cell fate through their complex isoform-specific and contextual-dependent cross-talk, to the extent that such functional interplay should be considered when devising therapies that target one or both these key signaling kinases.

Anticancer strategies based on the metabolic profile of tumor cells: therapeutic targeting of the Warburg effect

Tumor cells rely mainly on glycolysis for energy production even in the presence of sufficient oxygen, a phenomenon termed the Warburg effect, which is the most outstanding characteristic of energy metabolism in cancer cells. This metabolic adaptation is believed to be critical for tumor cell growth and proliferation, and a number of onco-proteins and tumor suppressors, including the PI3K/Akt/mTOR signaling pathway, Myc, hypoxia-inducible factor and p53, are involved in the regulation of this metabolic adaptation. Moreover, glycolytic cancer cells are often invasive and impervious to therapeutic intervention. Thus, altered energy metabolism is now appreciated as a hallmark of cancer and a promising target for cancer treatment. A better understanding of the biology and the regulatory mechanisms of aerobic glycolysis has the potential to facilitate the development of glycolysis-based therapeutic interventions for cancer. In addition, glycolysis inhibition combined with DNA damaging drugs or chemotherapeutic agents may be effective anticancer strategies through weakening cell damage repair capacity and enhancing drug cytotoxicity.