Reactive Oxygen Species Alterations Research Articles

Cranberries and Cancer: An Update of Preclinical Studies Evaluating the Cancer Inhibitory Potential of Cranberry and Cranberry Derived Constituents.

Cranberries are rich in bioactive constituents reported to influence a variety of health benefits, ranging from improved immune function and decreased infections to reduced cardiovascular disease and more recently cancer inhibition. A review of cranberry research targeting cancer revealed positive effects of cranberries or cranberry derived constituents against 17 different cancers utilizing a variety of in vitro techniques, whereas in vivo studies supported the inhibitory action of cranberries toward cancers of the esophagus, stomach, colon, bladder, prostate, glioblastoma and lymphoma. Mechanisms of cranberry-linked cancer inhibition include cellular death induction via apoptosis, necrosis and autophagy; reduction of cellular proliferation; alterations in reactive oxygen species; and modification of cytokine and signal transduction pathways. Given the emerging positive preclinical effects of cranberries, future clinical directions targeting cancer or premalignancy in high risk cohorts should be considered.

Enhancing cytokinin synthesis by overexpressing ipt alleviated drought inhibition of root growth through activating ROS-scavenging systems in Agrostis stolonifera.

Drought stress limits root growth and inhibits cytokinin (CK) production. Increases in CK production through overexpression of isopentenyltransferase (ipt) alleviate drought damages to promote root growth. The objective of this study was to investigate whether CK-regulated root growth was involved in the alteration of reactive oxygen species (ROS) production and ROS scavenging capacity under drought stress. Wild-type (WT) creeping bentgrass (Agrostis stolonifera L. 'Penncross') and a transgenic line (S41) overexpressing ipt ligated to a senescence-activated promoter (SAG12) were exposed to drought stress for 21 d in growth chambers. SAG12-ipt transgenic S41 developed a more extensive root system under drought stress compared to the WT. Root physiological analysis (electrolyte leakage and lipid peroxidation) showed that S41 roots exhibited less cellular damage compared to the WT under drought stress. Roots of SAG12-ipt transgenic S41 had significantly higher endogenous CK content than the WT roots under drought stress. ROS (hydrogen peroxide and superoxide) content was significantly lower and content of total and free ascorbate was significantly higher in S41 roots compared to the WT roots under drought stress. Enzymatic assays and transcript abundance analysis showed that superoxide dismutase, catalase, peroxidase, and dehydroascorbate reductase were significantly higher in S41 roots compared to the WT roots under drought stress. S41 roots also maintained significantly higher alternative respiration rates compared to the WT under drought stress. The improved root growth of transgenic creeping bentgrass may be facilitated by CK-enhanced ROS scavenging through antioxidant accumulation and activation of antioxidant enzymes, as well as higher alternative respiration rates when soil water is limited.

Long-Term Alteration of Reactive Oxygen Species Led to Multidrug Resistance in MCF-7 Cells.

Reactive oxygen species (ROS) play an important role in multidrug resistance (MDR). This study aimed to investigate the effects of long-term ROS alteration on MDR in MCF-7 cells and to explore its underlying mechanism. Our study showed both long-term treatments of H2O2 and glutathione (GSH) led to MDR with suppressed iROS levels in MCF-7 cells. Moreover, the MDR cells induced by 0.1 μM H2O2 treatment for 20 weeks (MCF-7/ROS cells) had a higher viability and proliferative ability than the control MCF-7 cells. MCF-7/ROS cells also showed higher activity or content of intracellular antioxidants like glutathione peroxidase (GPx), GSH, superoxide dismutase (SOD), and catalase (CAT). Importantly, MCF-7/ROS cells were characterized by overexpression of MDR-related protein 1 (MRP1) and P-glycoprotein (P-gp), as well as their regulators NF-E2-related factor 2 (Nrf2), hypoxia-inducible factor 1 (HIF-1α), and the activation of PI3K/Akt pathway in upstream. Moreover, several typical MDR mediators, including glutathione S-transferase-π (GST-π) and c-Myc and Protein Kinase Cα (PKCα), were also found to be upregulated in MCF-7/ROS cells. Collectively, our results suggest that ROS may be critical in the generation of MDR, which may provide new insights into understanding of mechanisms of MDR.

NADPH oxidases-do they play a role in TRPC regulation under hypoxia?

In the lung, acute alveolar hypoxia causes hypoxic pulmonary vasoconstriction (HPV) to maintain ventilation perfusion matching and thus optimal oxygenation of blood. In contrast, global chronic hypoxia triggers a pathological thickening of pulmonary arterial walls, called pulmonary vascular remodelling, leading to persistence of pulmonary hypertension (PH). Moreover, ischaemia or hypoxia can lead to a damage of pulmonary endothelial cells with subsequent oedema formation. Alterations in reactive oxygen species (ROS) have been suggested as a crucial mediator of such responses. Among the various sources of cellular ROS production, NADPH oxidases (NOXs) have been found to contribute to these physiological and pathophysiological signalling processes. NOXs are the only known examples that generate ROS as the primary function of the enzyme system. However, the downstream targets of NOX-derived ROS signalling in hypoxia are still not known. Canonical transient receptor potential (TRPC) channels recently have been recognised as directly or indirectly ROS-activated channels and have been shown to be essential for hypoxia-dependent vascular regulatory processes in the lung. Against this background, we here summarise the current knowledge on NOX-mediated TRPC channel signalling during hypoxia in the pulmonary circulation.

Photothermolysis mediated by gold nanorods modified with EGFR monoclonal antibody induces Hep-2 cells apoptosis in vitro and in vivo.

Gold nanorods (AuNRs) have been used in plasmonic photothermal therapy (PPTT), which is thought to be more efficient and selective than conventional photothermal therapy. The efficiency and safety of PPTT can be improved by functionally modifying the gold nanorods with proteins or biomolecules. In this study, AuNRs were modified with anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb), and the apoptotic potential of EGFRmAb-AuNR was assessed in Hep-2 cells in vitro and in vivo. The EGFRmAb modification had no obvious influence on the original optical property of the AuNRs, but it significantly increased the entry of AuNRs into Hep-2 cells. EGFRmAb-AuNRs, with appropriate laser irradiation, resulted in higher Hep-2 cells apoptosis than AuNRs did alone, in vitro, and was accompanied by alteration of reactive oxygen species (ROS) production, Ca2+ release, change in mitochondrial membrane potential (ΔΨm), cytochrome c (Cyt-c) release, active caspase-3 expression, and level of B-cell lymphoma 2 (Bcl-2) and B-cell lymphoma 2 protein-associated X protein (Bax). EGFRmAb-AuNR-mediated apoptosis in Hep-2 cells was also observed in vivo and had an inhibitive effect on growth of Hep-2 tumor xenografts. Our data suggest that the EGFRmAb modification improves AuNR-mediated apoptosis and may have the potential to be used clinically.

Loss of endogenous H2O2‐induced inhibition of ASIC1‐mediated Ca2+ influx in pulmonary artery smooth muscle cells following chronic hypoxia

Our laboratory has demonstrated an important role for acid‐sensing ion channel 1 (ASIC1) in mediating increased pulmonary arterial smooth muscle cell (PASMC) Ca2+ influx and enhanced agonist‐induced vasoconstriction following chronic hypoxia (CH)‐induced pulmonary hypertension. ASIC1 activity is highly sensitive to changes in the redox state of the cell; in particular, hydrogen peroxide (H2O2) has been shown to inhibit ASIC1 function. Furthermore, alterations in reactive oxygen species are known to contribute to the pathogenesis of pulmonary hypertension. Therefore, we hypothesize the increased ASIC1‐mediated store‐operated calcium entry (SOCE) in PASMCs following CH is due to decreased H2O2, attributable to a down regulation of superoxide dismutase (SOD). We found that PEG‐catalase augmented ASIC1‐dependent SOCE in PASMCs from control rats, but was without effect on SOCE in PASMCs from CH rats (4 wks @ 380 Torr). However, the addition of H2O2 inhibited SOCE in both groups. Additionally, SOD1 and SOD3 protein expression were decreased in isolated pulmonary arteries from CH rats compared to control. Together these data suggest that downregulation of SOD1 and SOD3 following CH results in a loss of endogenous H2O2‐induced inhibition of ASIC1‐dependent SOCE in PASMC. This work is supported by NIH HL‐09258 (NLJ) and HL‐07736 (BRW).

CD26 Truncation of GM-CSF and IL-3 Alters Their Functional Interactions

Abstract 1240CD26 (DPPIV) is a dipeptidyl peptidase that functions by enzymatically cleaving the penultimate proline or alanine of proteins, resulting in functional alterations. The expression and activity of CD26 is relevant in many disease states including obesity and cancer. Modulation of CD26 activity has been shown to increase homing and engraftment of both cord blood and bone marrow cells after transplant indicating the impressive therapeutic potential of CD26 activity altering compounds. Due to its importance in disease states and their subsequent treatments, it is relevant to study how the activity of CD26 alters the functions of the molecules it cleaves, and subsequently their interactions with each other.Mass spectrometry data from our laboratory has shown that CD26 can cleave the penultimate proline of GM-CSF resulting in the truncated form which has blunted signaling and function. Additional data has recently confirmed that CD26 can cleave IL-3 and results in its diminished function as well. Further, and more importantly, since GM-CSF and IL-3 are members of the IL-3 receptor family, and share a common receptor beta chain, we investigated if CD26 truncation of GM-CSF (TGM) or IL-3 (T3) could inhibit the functional activity of the full length (FL) alternate compound (i.e TGM inhibition of FL IL-3 activity or T3 inhibition of FL GM-CSF activity) in the TF-1 cell line and cord blood cells. We determined that both T3 and TGM could inhibit the colony formation induced by either FL GM-CSF or FL IL-3. This inhibition of function correlated with alterations in reactive oxygen species (ROS) levels that mimicked the truncated versions of either GM-CSF or IL-3 even in the presence of the full length molecules. Strikingly, this inhibition of colony formation did not require a 1:1 ratio of the full length to truncated. Rather, approximately 4–10 fold less truncated could be used to efficiently inhibit the colony formation activity of the full length, even across molecules. Interestingly, the ratio of T3 needed to block the full length GM-CSF (1.25ng/ml T3: 10ng/ml FL GM-CSF) was less than the amount of TGM needed to block the full length IL-3 (2.5ng/ml TGM: 10ng/ml FL IL-3) suggesting that T3 is better at blocking FL GM-CSF than TGM is at blocking FL IL-3. However, the ratios of truncated needed to block the function of self FL molecules are identical for both GM-CSF and IL-3 (1.25ng/ml truncated: 10ng/ml FL).Signaling and receptor binding studies were performed for GM-CSF with TF-1 and CD34+cord blood cells, and showed that the truncated GM-CSF inhibited the Stat-5 and JAK2 signaling of FL GM-CSF at less than a 1:1 (10ng/ml FL: 1.25 ng/ml TGM) ratio. Receptor binding studies found that TGM bound to the GM-CSF receptor more efficiently than the FL form but concentrations required to produce 50% maximum inhibition of binding (IC50) is 8-fold lower for TGM compared to FL-GM-CSF, indicating that T-GM-CSF is a better competitor for binding, than is FL-GM-CSF itself suggesting that this may be how TGM is blocking the effects of FL GM-CSF, and potentially IL-3, in our model. Finally, cells treated with TGM had diminished respiratory and glycolytic rates compared to those treated with full-length cytokine. These data provide the first evidence of relevant interactions, with functional consequences, of the importance of full length and CD26 truncated cytokines across molecules. Disclosures:Broxmeyer:CordUse: Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics: Consultancy.

Insulin-Like Growth Factor 1 Alleviates High-Fat Diet–Induced Myocardial Contractile Dysfunction

Obesity is often associated with reduced plasma insulin-like growth factor 1 (IGF-1) levels, oxidative stress, mitochondrial damage, and cardiac dysfunction. This study was designed to evaluate the impact of IGF-1 on high-fat diet–induced oxidative, myocardial, geometric, and mitochondrial responses. FVB and cardiomyocyte-specific IGF-1 overexpression transgenic mice were fed a low- (10%) or high-fat (45%) diet to induce obesity. High-fat diet feeding led to glucose intolerance, elevated plasma levels of leptin, interleukin 6, insulin, and triglyceride, as well as reduced circulating IGF-1 levels. Echocardiography revealed reduced fractional shortening, increased end-systolic and end-diastolic diameter, increased wall thickness, and cardiac hypertrophy in high-fat–fed FVB mice. High-fat diet promoted reactive oxygen species generation, apoptosis, protein and mitochondrial damage, reduced ATP content, cardiomyocyte cross-sectional area, contractile and intracellular Ca 2+ dysregulation (including depressed peak shortening and maximal velocity of shortening/relengthening), prolonged duration of relengthening, and dampened intracellular Ca 2+ rise and clearance. Western blot analysis revealed disrupted phosphorylation of insulin receptor and postreceptor signaling molecules insulin receptor substrate 1 (tyrosine/serine phosphorylation), Akt, glycogen synthase kinase 3β, forkhead transcriptional factors, and mammalian target of rapamycin, as well as downregulated expression of mitochondrial proteins peroxisome proliferator-activated receptor-γ coactivator 1α and uncoupling protein 2. Intriguingly, IGF-1 mitigated high-fat–diet feeding-induced alterations in reactive oxygen species, protein and mitochondrial damage, ATP content, apoptosis, myocardial contraction, intracellular Ca 2+ handling, and insulin signaling but not whole body glucose intolerance and cardiac hypertrophy. Exogenous IGF-1 treatment also alleviated high-fat diet–induced cardiac dysfunction. Our data revealed that IGF-1 alleviates high-fat diet–induced cardiac dysfunction despite persistent cardiac remodeling, possibly because of preserved cell survival, mitochondrial function, and insulin signaling.

Severe Exercise and Exercise Training Exert Opposite Effects on Human Neutrophil Apoptosis via Altering the Redox Status

Neutrophil spontaneous apoptosis, a process crucial for immune regulation, is mainly controlled by alterations in reactive oxygen species (ROS) and mitochondria integrity. Exercise has been proposed to be a physiological way to modulate immunity; while acute severe exercise (ASE) usually impedes immunity, chronic moderate exercise (CME) improves it. This study aimed to investigate whether and how ASE and CME oppositely regulate human neutrophil apoptosis. Thirteen sedentary young males underwent an initial ASE and were subsequently divided into exercise and control groups. The exercise group (n = 8) underwent 2 months of CME followed by 2 months of detraining. Additional ASE paradigms were performed at the end of each month. Neutrophils were isolated from blood specimens drawn at rest and immediately after each ASE for assaying neutrophil spontaneous apoptosis (annexin-V binding on the outer surface) along with redox-related parameters and mitochondria-related parameters. Our results showed that i) the initial ASE immediately increased the oxidative stress (cytosolic ROS and glutathione oxidation), and sequentially accelerated the reduction of mitochondrial membrane potential, the surface binding of annexin-V, and the generation of mitochondrial ROS; ii) CME upregulated glutathione level, retarded spontaneous apoptosis and delayed mitochondria deterioration; iii) most effects of CME were unchanged after detraining; and iv) CME blocked ASE effects and this capability remained intact even after detraining. Furthermore, the ASE effects on neutrophil spontaneous apoptosis were mimicked by adding exogenous H2O2, but not by suppressing mitochondrial membrane potential. In conclusion, while ASE induced an oxidative state and resulted in acceleration of human neutrophil apoptosis, CME delayed neutrophil apoptosis by maintaining a reduced state for long periods of time even after detraining.

Alterations in reactive oxygen species and dimethylarginine dimethylaminohydrolase-asymmetric dimethyl-arginine system in the process of endothelial cell senescence induced by high glucose

To investigate the changes in reactive oxygen species (ROS) and dimethyl- arginine dimethylaminohydrolase-asymmetric dimethylarginine (DDAH-ADMA) system in the process of endothelial cell senescence after exposure to high glucose. The human umbilical vein endothelial cells (HUVECs) were cultured with different concentrations of glucose, e.g. 5.5 mmol/L (normal level), and high levels as 11.0, 22.0 and 33.0 mmol/L, for 48 hours, respectively. Subsequently, SA-β-gal staining was used to evaluate senescence of cells. Telomerase activity was detected by polymerase chain reaction-enzyme linked immunosorbent assay (PCR-ELISA). The intracellular ROS level was measured by flow cytometry. The ADMA concentration and DDAH activity were determined with high-performance liquid chromatography. Compared with normal glucose concentration group, after the endothelial cells were treated with high glucose concentration (11.0-33.0 mmol/L) for 48 hours, the number of SA-β-gal positive cells was increased significantly [(7.00±1.73)%, (12.67±2.03)%, (16.00±2.26)% vs. (4.00±1.33)%, P>0.05, P<0.05, P<0.05] and the telomerase activity was inhibited dramatically [(91.32±4.01)%, (78.44±3.78)%, (56.04±3.35)% vs. 100%, all P<0.05]. The ROS level (mfi) was increased in all high glucose groups (159.84±27.52, 188.99±18.77, 244.56±20.96 vs.117.11±18.76, P<0.05 or P<0.01). At the same time, the ADMA (μmol/L) production was increas ed (0.78±0.14, 0.88±0.18, 1.08±0.15 vs. 0.70±0.12, P>0.05, P<0.05, P<0.05), and DDAH activity was decreased [(91.32±4.01)%, (78.44±3.78)%, (56.04±3.35)% vs.100%, all P<0.05]. High glucose can accelerate endothelial cells senescence in dose-dependent manner and the underlying mechanism may be related to an increased oxidative stress and change in DDAH-ADMA system.

The Voltage-Gated Proton Channel HVCN1 Co-Localizes with B Cell Receptor and Is Involved in Class Switch Recombination in Vivo

HVCN1 is a highly-conserved voltage-gated proton channel. Voltage-gated proton currents have been recorded in lymphocytes but their functions in B cells remain unknown. We isolated HVCN1 in a proteomic survey of plasma membrane proteins in mantle cell lymphoma (MCL) in leukemic phase. In normal lymphocytes, HVCN1 expression was restricted to the B-cell lineage; HVCN1 was highly expressed in mantle zone cells but down-regulated in germinal center (GC) cells undergoing receptor affinity maturation and class-switch recombination (CSR). Highest level expression was also observed in Chronic Lymphocytic Leukemia (CLL) cells from the peripheral blood. In MCL tumors, HVCN1 was expressed in circulating cells but absent from involved lymph nodes, whereas in diffuse large B cell lymphoma (DLBCL), its expression correlated with cases with a low proliferation index. Thus, in both primary and neoplastic B cells, HVCN1 expression appears to be associated with a non-proliferative phenotype. In human primary resting B cells and B cell lines, HVCN1 directly interacted with the B cell receptor (BCR) complex, as shown by Igβ and HVCN1 reciprocal immunoprecipitation experiments. We also found by confocal microscopy and subcellular fractionation, that upon BCR engagement the channel was internalized with the antigen receptor and the two proteins co-migrated to the endo-lysosomal, MHC class II (MHC-II) containing compartments (MIICs). When overexpressed in a hen egg lysozyme (HEL)-specific B cell clone, LK35.2, HVCN1 showed a basal phosphorylation which increased with HEL stimulation. The increased phosphorylation corresponded to an increase in proton conductance, termed “enhanced gating mode” and it was PKC dependent. We then asked whether HVCN1 over-expression could influence MHC II antigen presentation and if the effect could be mediated by changes in MIICs pH. Indeed, presentation of HEL peptides to a T cell clone was impaired in LK35.2 and A20 D1.3 cells, where HVCN1 had been re-introduced; effect was stronger for plate-bound antigen than for soluble antigen. The reduced antigen presentation was accompanied by an increase in endo-lysosomal pH, from pH4.9 ± 0.2 to 6.3 ± 0.1 (which may reflect HVCN1 channel-mediated proton flux out of the organelles), as measured with an anti-IgM antibody conjugated to a pH sensitive dye in HVCN1 over-expressing cells. Evidently, the presence of HVCN1 leads to increased endo-lysosomal pH, consistent with H+ current from the lysosomal compartment into the cytosol. Hence, active antigen presenting cells, like GC cells, might down-regulate HVCN1 expression to maximize the effect of antigen presentation. In order to investigate the role of HVCN1 in vivo, we used a HVCN1-deficient mouse line generated by genetrap insertion. These mice showed no obvious changes in numbers or composition of B-cell subpopulations. Immunization of HVCN1-deficient mice with a T-dependent antigen resulted in a defect in CSR to all IgG subclasses, particularly marked for the IgG2b, whereas in contrast, no differences were observed in IgM secretion, suggesting a pivotal role for HVCN1 during antigen-driven B-cell activation and subsequent CSR. HVCN1 may influence B-cell activation through alteration of reactive oxygen species (ROS) as HVCN1-deficient B cells showed reduced ROS production following BCR activation, a sign of suboptimal NADPH oxidase activity. It has been postulated that proton channels are required to counterbalance the electrogenic activity of NADPH oxidase during ROS production. Our data suggest that this mechanism also occurs in vivo and shed new light on the role of ROS in B cell activation and downstream effects.

Andrographolide induces cell cycle arrest at G2/M phase and cell death in HepG2 cells via alteration of reactive oxygen species

The cytotoxicity of andrographolide to HepG2 human hepatoma cells was investigated in the present study. Growth of HepG2 cells was affected in the presence of andrographolide with an IC 50 of 40.2 μM after 48 h treatment. Flow cytometric analysis and DNA fragmentation assay revealed that andrographolide induced cell cycle arrest at G2/M phase and a late apoptosis of the cells. The occurrence of cell cycle arrest was accompanied by the collapse of mitochondrial membrane potential (MMP) and an intracellular increase of hydrogen peroxide (H 2O 2) but a decrease of superoxide radicals (O 2 −) and reduced glutathione. In the treated cells, expression of Bax as well as the transcriptional controller of this pro-apoptotic gene, p53, was upregulated but not other apoptotic proteins such as Bad, Bcl-2 and Bcl-X L. Although the activity of caspase-3, which has direct effect on apoptosis, was also enhanced by the presence of andrographolide, cell death of HepG2 could neither be prevented by a specific inhibitor of capsase-3 nor the pan-caspase inhibitor-zVAD (Val-Ala-Asp), indicating that it was a caspase-independent cell death. Since the overall percentage of apoptotic cells was relatively small throughout the experimental studies, we conclude that the cytotoxic effect of andrographolide on HepG2 cells is primary attributed to the induction of cell cycle arrest via the alteration of cellular redox status.

The Release of Bystander Factor(s) from Tissue Explant Cultures of Rainbow Trout (Onchorhynchus mykiss) after Exposure to γ Radiation

The bystander response has been documented in cell lines and cell cultures derived from aquatic species over the past several years. However, little work has been undertaken to identify a similar bystander response in tissue explant cultures from fish. In this study, indirect effects of ionizing gamma radiation on tissue explant cultures of fish were investigated. Tissue explants in culture were exposed to 0.5 Gy and 5 Gy gamma radiation from a 60Co teletherapy unit. A bystander response in Epithelioma papulosum cyprini (EPC) cells exposed to gamma-irradiated tissue conditioned medium from rainbow trout explants was investigated, and the effects on cell survival were quantified by the clonogenic survival assay. Dichlorofluorescein and rhodamine 123 fluorescent dyes were used to identify alterations in reactive oxygen species (ROS) and mitochondrial membrane potential (MMP), respectively. Results indicate a different response for the three tissue types investigated. Clonogenic assay results vary from a decrease in cell survival (gill) to no effect (skin) to a stimulatory effect (spleen). Results from fluorescence assays of ROS and MMP show similarities to clonogenic assay results. This study identifies a useful model for further studies relating to the bystander effect in aquatic organisms in vivo and ex vivo.

Role of c-MET in Upper Aerodigestive Malignancies — From Biology to Novel Therapies

Overactivation and defective downregulation of receptor tyrosine kinase (RTK) pathways have been implicated in human carcinogenesis. RTKs represent an important class of anticancer novel therapeutic target. Some RTKs are known to be protooncogenes that can mediate signal transduction, alteration of reactive oxygen species (ROS), cellular proliferation, cell motility and migration, apoptosis, and survival. c-MET is a unique RTK that regulates a wide variety of cellular functions. c-MET has been shown to be overexpressed or mutated in a variety of human malignancies. Stimulation of c-MET via its natural ligand hepatocyte growth factor/ scatter factor (HGF/SF) leads to a plethora of biological and biochemical effects in the cell. Activation of c-MET signaling can lead to cell motility and scattering, angiogenesis, proliferation, branching morphogenesis, invasion, and eventual metastasis. This review summarizes the structure and functions of c-MET, with particular emphasis on its role in upper aerodigestive malignancies. The unique biological functions altered by c-MET and its mutations are discussed as well. Finally, c-MET, when mutated or overexpressed in malignant cells, serves as an important therapeutic target, and the most recent data with respect to its inhibition are also summarized in this review.