Manipulation of cellular redox parameters for improving therapeutic responses in B-cell lymphoma and multiple myeloma

Oxidative Stress and Inflammation in B-Cell Lymphomas

Mature lymphoid neoplasms arise de novo or by the transformation of more indolent lymphomas in a process that relies on the stepwise accumulation of genomic and transcriptomic alterations. The microenvironment and neoplastic precursor cells are heavily influenced by pro-inflammatory signaling, regulated in part by oxidative stress and inflammation. Reactive oxygen species (ROSs) are by-products of cellular metabolism able to modulate cell signaling and fate. Moreover, they play a crucial role in the phagocyte system, which is responsible for antigen presentation and the selection of mature B and T cells under normal conditions. Imbalances in pro-oxidant and antioxidant signaling can lead to physiological dysfunction and disease development by disrupting metabolic processes and cell signaling. This narrative review aims to analyze the impact of reactive oxygen species on lymphomagenesis, specifically examining the regulation of microenvironmental players, as well as the response to therapy for B-cell-derived non-Hodgkin lymphomas. Further research is needed to investigate the involvement of ROS and inflammation in the development of lymphomas, which may unravel disease mechanisms and identify innovative therapeutic targets.

Arsenic and Diabetes Mellitus: A Putative Role for the Immune System

Diabetes mellitus (DM) is an enormous public health issue worldwide. Recent data suggest that chronic arsenic exposure is linked to the risk of developing type 1 and type 2 DM, albeit the underlying mechanisms are unclear. This review discusses the role of the immune system as a link to possibly explain some of the mechanisms of developing T1DM or T2DM associated with arsenic exposure in humans, animal models, and in vitro studies. The rationale for the hypothesis includes: (1) Arsenic is a well-recognized modulator of the immune system; (2) arsenic exposures are associated with increased risk of DM; and (3) dysregulation of the immune system is one of the hallmarks in the pathogenesis of both T1DM and T2DM. A better understanding of DM in association with immune dysregulation and arsenic exposures may help to understand how environmental exposures modulate the immune system and how these effects may impact the manifestation of disease.

Modulation of Cellular Redox Parameters for Improving Therapeutic Responses in Multiple Myeloma

Raised oxidative stress and abnormal redox status are typical features of multiple myeloma cells, and the identification of the intimate mechanisms that regulate the relationships between neoplastic cells and redox homeostasis may reveal possible new anti-myeloma therapeutic targets to increase the effectiveness of anti-myeloma drugs synergistically or to eradicate drug-resistant clones while reducing toxicity toward normal cells. An alteration of the oxidative state is not only responsible for the onset of multiple myeloma and its progression, but it also appears essential for the therapeutic response and for developing any chemoresistance. Our review aimed to evaluate the literature’s current data on the effects of oxidative stress on the response to drugs generally employed in the therapy of multiple myeloma, such as proteasome inhibitors, immunomodulators, and autologous transplantation. In the second part of the review, we analyzed the possibility of using other substances, often of natural origin, to modulate the oxidative stress to interfere with the progression of myelomatous disease.

Lack of Adverse Effects of Cold Physical Plasma-Treated Blood from Leukemia Patients: A Proof-of-Concept Study

Chronic lymphocytic leukemia (CLL) is the most common blood malignancy with multiple therapeutic challenges. Cold physical plasma has been considered a promising approach in cancer therapy in recent years. In this study, we aimed to evaluate the cytotoxic effect of cold plasma or plasma-treated solutions (PTS) on hematologic parameters in the whole blood of CLL patients. The mean red blood cell count, white blood cell (WBC) count, platelet and hemoglobin counts, and peripheral blood smear images did not significantly differ between treated and untreated samples in either CLL or healthy individuals. However, both direct plasma and indirect PTS treatment increased lipid peroxidation and RNS deposition in the whole blood of CLL patients and in healthy subjects. In addition, the metabolic activity of WBCs was decreased with 120 s of cold plasma or PTS treatment after 24 h and 48 h. However, cold plasma and PTS treatment did not affect the prothrombin time, partial thromboplastin time, nor hemolysis in either CLL patients or in healthy individuals. The present study identifies the components of cold plasma to reach the blood without disturbing the basic parameters important in hematology, confirming the idea that the effect of cold plasma may not be limited to solid tumors and possibly extends to hematological disorders. Further cellular and molecular studies are needed to determine which cells in CLL patients are targeted by cold plasma or PTS.

Specific targeting of the KRAS mutational landscape in myeloma as a tool to unveil the elicited antitumor activity

Alterations in KRAS have been identified as the most recurring somatic variants in the multiple myeloma (MM) mutational landscape. Combining DNA and RNA sequencing, we studied 756 patients and observed KRAS as the most frequently mutated gene in patients at diagnosis; in addition, we demonstrated the persistence or de novo occurrence of the KRAS aberration at disease relapse. Small-molecule inhibitors targeting KRAS have been developed; however, they are selective for tumors carrying the KRASG12C mutation. Therefore, there is still a need to develop novel therapeutic approaches to target the KRAS mutational events found in other tumor types, including MM. We used AZD4785, a potent and selective antisense oligonucleotide that selectively targets and downregulates all KRAS isoforms, as a tool to dissect the functional sequelae secondary to KRAS silencing in MM within the context of the bone marrow niche and demonstrated its ability to significantly silence KRAS, leading to inhibition of MM tumor growth, both in vitro and in vivo, and confirming KRAS as a driver and therapeutic target in MM.

Targeting Reactive Oxygen Species Metabolism to Induce Myeloma Cell Death

Multiple myeloma (MM) is a common hematological disease characterized by the accumulation of clonal malignant plasma cells in the bone marrow. Over the past two decades, new therapeutic strategies have significantly improved the treatment outcome and patients survival. Nevertheless, most MM patients relapse underlying the need of new therapeutic approaches. Plasma cells are prone to produce large amounts of immunoglobulins causing the production of intracellular ROS. Although adapted to high level of ROS, MM cells die when exposed to drugs increasing ROS production either directly or by inhibiting antioxidant enzymes. In this review, we discuss the efficacy of ROS-generating drugs for inducing MM cell death and counteracting acquired drug resistance specifically toward proteasome inhibitors.

Deep MRD profiling defines outcome and unveils different modes of treatment resistance in standard- and high-risk myeloma

Patients with multiple myeloma (MM) carrying standard- or high-risk cytogenetic abnormalities (CAs) achieve similar complete response (CR) rates, but the later have inferior progression-free survival (PFS). This questions the legitimacy of CR as a treatment endpoint and represents a biological conundrum regarding the nature of tumor reservoirs that persist after therapy in high-risk MM. We used next-generation flow (NGF) cytometry to evaluate measurable residual disease (MRD) in MM patients with standard- vs high-risk CAs (n = 300 and 90, respectively) enrolled in the PETHEMA/GEM2012MENOS65 trial, and to identify mechanisms that determine MRD resistance in both patient subgroups (n = 40). The 36-month PFS rates were higher than 90% in patients with standard- or high-risk CAs achieving undetectable MRD. Persistent MRD resulted in a median PFS of ∼3 and 2 years in patients with standard- and high-risk CAs, respectively. Further use of NGF to isolate MRD, followed by whole-exome sequencing of paired diagnostic and MRD tumor cells, revealed greater clonal selection in patients with standard-risk CAs, higher genomic instability with acquisition of new mutations in high-risk MM, and no unifying genetic event driving MRD resistance. Conversely, RNA sequencing of diagnostic and MRD tumor cells uncovered the selection of MRD clones with singular transcriptional programs and reactive oxygen species-mediated MRD resistance in high-risk MM. Our study supports undetectable MRD as a treatment endpoint for patients with MM who have high-risk CAs and proposes characterizing MRD clones to understand and overcome MRD resistance. This trial is registered at www.clinicaltrials.gov as #NCT01916252.

Radioprotective Agents and Enhancers Factors. Preventive and Therapeutic Strategies for Oxidative Induced Radiotherapy Damages in Hematological Malignancies

Radiation therapy plays a critical role in the management of a wide range of hematologic malignancies. It is well known that the post-irradiation damages both in the bone marrow and in other organs are the main causes of post-irradiation morbidity and mortality. Tumor control without producing extensive damage to the surrounding normal cells, through the use of radioprotectors, is of special clinical relevance in radiotherapy. An increasing amount of data is helping to clarify the role of oxidative stress in toxicity and therapy response. Radioprotective agents are substances that moderate the oxidative effects of radiation on healthy normal tissues while preserving the sensitivity to radiation damage in tumor cells. As well as the substances capable of carrying out a protective action against the oxidative damage caused by radiotherapy, other substances have been identified as possible enhancers of the radiotherapy and cytotoxic activity via an oxidative effect. The purpose of this review was to examine the data in the literature on the possible use of old and new substances to increase the efficacy of radiation treatment in hematological diseases and to reduce the harmful effects of the treatment.

ROS Overproduction Sensitises Myeloma Cells to Bortezomib-Induced Apoptosis and Alleviates Tumour Microenvironment-Mediated Cell Resistance

Multiple myeloma (MM) is a plasma cell neoplasm that remains incurable due to innate or acquired resistance. Although MM cells produce high intracellular levels of reactive oxygen species (ROS), we hypothesised that they could remain sensitive to ROS unbalance. We tested if the inhibition of ROS, on one hand, or the overproduction of ROS, on the other, could (re)sensitise cells to bortezomib (BTZ). Two drugs were used in a panel of MM cell lines with various responses to BTZ: VAS3947 (VAS), an inhibitor of NADPH oxidase and auranofin (AUR), an inhibitor of thioredoxin reductase (TXNRD1), an antioxidant enzyme overexpressed in MM cells. We used several culture models: in suspension, on a fibronectin layer, in coculture with HS-5 mesenchymal cells, and/or in 3-D culture (or spheroids) to study the response of MM primary cells and cell lines. Several MM cell lines were sensitive to VAS but the combination with BTZ showed antagonistic or additive effects at best. By contrast, in all culture systems studied, the combined AUR/BTZ treatment showed synergistic effects on cell lines, including those less sensitive to BTZ and primary cells. MM cell death is due to the activation of apoptosis and autophagy. Modulating the redox balance of MM cells could be an effective therapy for refractory or relapse post-BTZ patients.

Cyclin D1 unbalances the redox status controlling cell adhesion, migration, and drug resistance in myeloma cells

The interactions of multiple myeloma (MM) cells with their microenvironment are crucial for pathogenesis. MM cells could interact differentially with their microenvironment depending on the type of cyclin D they express. We established several clones that constitutively express cyclin D1 from the parental RPMI8226 MM cell line and analyzed the impact of cyclin D1 expression on cell behavior. We performed a gene expression profiling study on cyclin D1-expressing vs. control cells and validated the results by semi-quantitative RT-PCR. The expression of cyclin D1 altered the transcription of genes that control adhesion and migration. We confirmed that cyclin D1 increases cell adhesion to stromal cells and fibronectin, stabilizes F-actin fibers, and enhances chemotaxis and inflammatory chemokine secretion. Both control and cyclin D1-expressing cells were more resistant to acute carfilzomib treatment when cultured on stromal cells than in suspension. However, this resistance was specifically reduced in cyclin D1-expressing cells after pomalidomide pre-treatment that modifies tumor cell/microenvironment interactions. Transcriptomic analysis revealed that cyclin D1 expression was also associated with changes in the expression of genes controlling metabolism. We also found that cyclin D1 expression disrupted the redox balance by producing reactive oxygen species. The resulting oxidative stress activated the p44/42 mitogen-activated protein kinase (or ERK1/2) signaling pathway, increased cell adhesion to fibronectin or stromal cells, and controlled drug sensitivity.

Our results have uncovered a new function for cyclin D1 in the control of redox metabolism and interactions of cyclin D1-expressing MM cells with their bone marrow microenvironment.

Curcumin ameliorates the in vitro efficacy of carfilzomib in human multiple myeloma U266 cells targeting p53 and NF-κB pathways

Multiple myeloma (MM) is a malignant B-cell neoplasm with accumulation of malignant plasma cells in bone marrow. Pharmacological therapy improves response frequency even if with various associated toxicities. Herein, we investigated if combination of curcumin with carfilzomib (CFZ) can induce a better cytotoxic effect on in vitro cultured U266 cells. Cell viability data showed that curcumin significantly ameliorates CFZ cytotoxic effect. Furthermore, curcumin alone did not affect proteasome at the tested dose, confirming the involvement of different mechanisms in the observed effects. U266 cells exposure to curcumin or CFZ increased reactive species (RS) levels, although their production did not appear further potentiated following drugs combination. Interestingly, NF-κB nuclear accumulation was reduced by treatment with CFZ or curcumin, and was more deeply decreased in cells treated with CFZ-curcumin combinations, very likely due to the different mechanisms through which they target NF-κB. Our results confirmed the induction of p53/p21 axis and G0/G1 cell cycle arrest in anticancer activities of both drugs, an effect more pronounced for the CFZ-curcumin tested combinations. Furthermore, curcumin addition enhanced CFZ proapoptotic effect. These findings evidence that curcumin can ameliorate CFZ efficacy, and lead us to hypothesize that this effect might be useful to optimize CFZ therapy in MM patients.

Characteristics of BAFF and APRIL factor expression in multiple myeloma and clinical significance

The characteristics of the proliferation of B-cell activating factor (BAFF) and the proliferation-inducing ligand (APRIL) mRNA expression in mononuclear cell in multiple myeloma patients were detected, and the correlation was analyzed between the BAFF and APRIL concentrations in plasma and tumor burden parameters of multiple myeloma. Bone marrow samples from 60 patients with multiple myeloma and 20 healthy persons taken as controls, were collected. Bone marrow mononuclear cells (BMMCs) were harvested, and plasma was extracted. BAFF and APRIL mRNA expression was quantified using real-time fluorescent quantitative PCR in the BMMCs. ELISA was used to detect the characteristics of gene and protein expression of BAFF and APRIL in KM3 cell line. The BAFF and APRIL mRNA expression in initial treatment group, remission group and non-remission group were markedly higher than that in control group (P<0.05). The expression in initial treatment group and non-remission group was markedly higher than that of the control group (P<0.05). APRIL mRNA expression in mononuclear cells in stage III patients was markedly higher than that in stage II patients (P<0.05). There was positive correlation between APRIL and BAFF concentration in multiple myeloma (P=0.0027). In conclusion, for the gene and protein expression of BAFF and APRIL in patients with multiple myeloma, the initial treatment group and non-remission are higher than control and remission group. The higher the stage was, the more the factors were expressed. Characteristics of expression of BAFF and APRIL may be used as a new index to evaluate the prognosis of multiple myeloma.

Arsenic Trioxide Induces Apoptosis via Specific Signaling Pathways in HT-29 Colon Cancer Cells

BACKGROUND

Arsenic trioxide (ATO) is highly effective in the treatment of patients with acute promyelocytic leukemia (APL). It is a chemotherapeutic agent that has been shown to induce apoptosis in several tumor cell lines. However, research into its effects on colon carcinoma cells is still very limited. We previously reported that ATO is cytotoxic and causes DNA damage in HT-29 human colorectal adenocarcinoma cells. In the present study, we further evaluated its effect on oxidative stress (OS), and examined its apoptotic mechanisms of action on HT-29 cells.

METHODS

OS was assessed by spectrophotometric measurements of MDA levels while cell cycle analysis was evaluated by flow cytometry to determine whether ATO induces cell cycle arrest. Its effect on early apoptosis was also evaluated by flow cytometry using Annexin V-FITC/PI staining. Fluorescence microscopy was used to detect the morphological changes, and Western blotting was carried out to determine the expression of apoptosis-related proteins.

RESULTS

The lipid peroxidation assay revealed a dose-dependent increase in MDA production. DAPI staining showed morphological changes in the cell's nucleus due to apoptosis. Cell cycle analysis and Annexin V-FITC assay also demonstrated a dose-dependent effect of ATO in the accumulation of cells at the sub G1 phase, and the percentages of Annexin V-positive cells, respectively. Western blot data showed that ATO upregulated the expression of caspase 3, Bax, and cytochrome C, and down-regulated the expression of Bcl-2.

CONCLUSION

Taken together, our findings indicate that ATO induces OS and cytotoxicity in HT-29 cells through the mitochondria mediated intrinsic pathway of apoptosis.

Oxidative stress and proteasome inhibitors in multiple myeloma

Multiple myeloma is a form of plasma cell neoplasm that accounts for approximately 10% of all hematological malignancies. Recently, several novel drugs have been discovered that almost doubled the overall survival of multiple myeloma patients. One of these drugs, the first-in-class proteasome inhibitor bortezomib (Velcade) has demonstrated remarkable response rates in multiple myeloma patients, and yet, currently this disease remains incurable. The major factor undermining the success of multiple myeloma treatment is a rapidly emerging resistance to the available therapy. Thus, the development of stand-alone or adjuvant anti-myeloma agents becomes of paramount importance. Overproduction of intracellular reactive oxygen species (ROS) often accompanies malignant transformation due to oncogene activation and/or enhanced metabolism in tumor cells. As a result, these cells possess higher levels of ROS and lower levels of antioxidant molecules compared to their normal counterparts. Unbalanced production of ROS leads to oxidative stress which, if left unchecked, could be toxic for the cell. In multiple myeloma cells where high rates of immunoglobulin synthesis is an additional factor contributing to overproduction of ROS, further induction of oxidative stress can be an effective strategy to cope with this disease. Here we will review the available data on the role of oxidative stress in the cytotoxicity of proteasome inhibitors and the use of ROS-inducing compounds as anti-myeloma agents.

Drug metabolism and clearance system in tumor cells of patients with multiple myeloma

Resistance to chemotherapy is a major limitation of cancer treatments with several molecular mechanisms involved, in particular altered local drug metabolism and detoxification process. The role of drug metabolism and clearance system has not been satisfactorily investigated in Multiple Myeloma (MM), a malignant plasma cell cancer for which a majority of patients escapes treatment. The expression of 350 genes encoding for uptake carriers, xenobiotic receptors, phase I and II Drug Metabolizing Enzymes (DMEs) and efflux transporters was interrogated in MM cells (MMCs) of newly-diagnosed patients in relation to their event free survival. MMCs of patients with a favourable outcome have an increased expression of genes coding for xenobiotic receptors (RXRα, LXR, CAR and FXR) and accordingly of their gene targets, influx transporters and phase I/II DMEs. On the contrary, MMCs of patients with unfavourable outcome displayed a global down regulation of genes coding for xenobiotic receptors and the downstream detoxification genes but had a high expression of genes coding for ARNT and Nrf2 pathways and ABC transporters. Altogether, these data suggests ARNT and Nrf2 pathways could be involved in MM primary resistance and that targeting RXRα, PXR, LXR and FXR through agonists could open new perspectives to alleviate or reverse MM drug resistance.

Toward understanding induction of oxidative stress and apoptosis by proteasome inhibitors

SIGNIFICANCE

Proteasome inhibitors (PIs) are used in the clinic for the treatment of hematopoietic malignancies. PI inhibitors induce endoplasmatic reticulum (ER) stress and oxidative stress, disruption of signaling pathways, mitochondrial dysfunction, and, eventually, cell death by apoptosis. PIs designated as clinical candidates include natural product derivatives and compounds developed by rational design and feature a wide diversity of structural elements. The vast amount of literature on this topic underscores PIs significance in driving basic research alongside therapeutic benefit.

RECENT ADVANCES

Research in recent years has brought an in-depth insight into the molecular mechanisms of PI-induced apoptosis. However, there are some paradoxes and controversies in the literature. In this review, the advances and uncertainties, in particular on the time course events that make cells commit to apoptosis, are discussed. In addition, some mechanisms of evolved PI resistance are presented, and speculations on the difference in sensitivity between cell or tumor types are brought forward. The review concludes by giving an outlook of recent methods that may be employed to describe the system biology of how PIs impact cell survival decisions.

CRITICAL ISSUES

The biology of ER stress, reactive oxygen species (ROS) production, and apoptosis as induced by PIs is not well understood. Absorbed by the strong focus on PIs, one might overlook the importance of proteasome activity activators or modulators and the study of enzymatic pathways that lie up- or downstream from the proteasome function.

FUTURE DIRECTIONS

An increased understanding of the systems biology at mRNA and protein levels and the kinetics behind the interaction between PIs and cells is imperative. The design and synthesis of subunit specific inhibitors for each of the seven known proteasome activities and for the enzymes associated to proteasomes will aid in unraveling biology of the ubiquitin-proteasome system in relation to ER stress, ROS production, and apoptosis and will generate leads for therapeutic intervention.

Copper-zinc superoxide dismutase-mediated redox regulation of bortezomib resistance in multiple myeloma

Multiple myeloma (MM) is an incurable B-cell malignancy. The proteasome inhibitor bortezomib (BTZ) is a frontline MM drug; however, intrinsic or acquired resistance to BTZ remains a clinical hurdle. As BTZ induces oxidative stress in MM cells, we queried if altered redox homeostasis promotes BTZ resistance. In primary human MM samples, increased gene expression of copper–zinc superoxide dismutase (CuZnSOD or SOD1) correlated with cancer progression, high-risk disease, and adverse overall and event-free survival outcomes. As an in vitro model, human MM cell lines (MM.1S, 8226, U266) and the BTZ-resistant (BR) lines (MM.1SBR, 8226BR) were utilized to determine the role of antioxidants in intrinsic or acquired BTZ-resistance. An up-regulation of CuZnSOD, glutathione peroxidase-1 (GPx-1), and glutathione (GSH) were associated with BTZ resistance and attenuated prooxidant production by BTZ. Enforced overexpression of SOD1 induced BTZ resistance and pharmacological inhibition of CuZnSOD with disulfiram (DSF) augmented BTZ cytotoxicity in both BTZ-sensitive and BTZ-resistant cell lines. Our data validates CuZnSOD as a novel therapeutic target in MM. We propose DSF as an adjuvant to BTZ in MM that is expected to overcome intrinsic and acquired BTZ resistance as well as augment BTZ cytotoxicity.

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Multiple myeloma (MM) displays intrinsic/adaptive resistance to bortezomib (BTZ).

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An up-regulation of antioxidant levels is observed in BTZ-resistant MM cell lines.

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Inhibition of CuZnSOD increases BTZ cytotoxicity in BTZ naïve/resistant cells.

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We propose disulfiram as a combination chemotherapy drug to inhibit relapse in MM.

A novel model of chronic wounds: importance of redox imbalance and biofilm-forming bacteria for establishment of chronicity

Chronic wounds have a large impact on health, affecting ∼6.5 M people and costing ∼$25B/year in the US alone. We previously discovered that a genetically modified mouse model displays impaired healing similar to problematic wounds in humans and that sometimes the wounds become chronic. Here we show how and why these impaired wounds become chronic, describe a way whereby we can drive impaired wounds to chronicity at will and propose that the same processes are involved in chronic wound development in humans. We hypothesize that exacerbated levels of oxidative stress are critical for initiation of chronicity. We show that, very early after injury, wounds with impaired healing contain elevated levels of reactive oxygen and nitrogen species and, much like in humans, these levels increase with age. Moreover, the activity of anti-oxidant enzymes is not elevated, leading to buildup of oxidative stress in the wound environment. To induce chronicity, we exacerbated the redox imbalance by further inhibiting the antioxidant enzymes and by infecting the wounds with biofilm-forming bacteria isolated from the chronic wounds that developed naturally in these mice. These wounds do not re-epithelialize, the granulation tissue lacks vascularization and interstitial collagen fibers, they contain an antibiotic-resistant mixed bioflora with biofilm-forming capacity, and they stay open for several weeks. These findings are highly significant because they show for the first time that chronic wounds can be generated in an animal model effectively and consistently. The availability of such a model will significantly propel the field forward because it can be used to develop strategies to regain redox balance that may result in inhibition of biofilm formation and result in restoration of healthy wound tissue. Furthermore, the model can lead to the understanding of other fundamental mechanisms of chronic wound development that can potentially lead to novel therapies.

Oxidative stress markers and mitochondrial antioxidant enzyme expression are increased in aggressive Hodgkin lymphomas

AIMS

Hodgkin lymphoma treatments are largely based on the generation of reactive oxygen species, but increased expression of antioxidant enzymes may contribute to chemoresistance. The aims of this study were: to define the extent and prognostic value of oxidative stress marker and antioxidant enzyme expression in Hodgkin lymphomas; and to investigate a potential association between antioxidant enzymes and chemoresistance.

METHODS AND RESULTS

We immunohistochemically assessed expression of peroxiredoxin (Prx) II, Prx III, Prx V, Prx VI, manganese superoxide dismutase (MnSOD), 8-hydroxydeoxyguanosine (8-OHdG) and nitrotyrosine in 99 cases of uniformly treated Hodgkin lymphoma. Localization of 8-OHdG was assessed using transmission electron microscopy, which demonstrated expression in the cytosol and mitochondria. 8-OHdG expression in Reed-Sternberg (RS) cells was associated with advanced stage (P = 0.006) and a lower International Prognostic Score (P = 0.004). Prx III expression in reactive cellular infiltrate was associated with advanced stage (P = 0.002) and B-symptoms (P = 0.0006). Strong cytoplasmic Prx V immunostaining was associated with a low rate of complete response to chemotherapy (P = 0.043). MnSOD immunostaining in RS cells was related to advanced stage (P = 0.031) and to poorer relapse-free survival (RFS) (P = 0.033). Low 8-OHdG expression in the nuclei of RS cells was a predictor of poorer RFS (P = 0.038). Both 8-OHdG and MnSOD were also significant RFS predictors in multivariate analysis.

CONCLUSIONS

Our results suggest that significant oxidative stress exists in Hodgkin lymphomas, both in RS cells and in reactive cellular infiltrates. Mitochondrial antioxidant enzymes are induced in the most aggressive forms of the disease, and they may play some part in chemoresistance.

Oxidative stress in oncohematologic diseases: an update

An increased risk of cancer in various organs has been related to oxidative stress and several studies have revealed the mechanism by which continued oxidative stress can lead to chronic inflammation, which in turn could mediate most chronic diseases including cancer. A variety of transcription factors may be activated in consequence of oxidative stress, leading to the expression of over 500 different genes, including those for growth factors, inflammatory cytokines, chemokines, cell cycle regulatory molecules and anti-inflammatory molecules. In this review, the data related to the action of oxidative stress on the onset of various oncohematologic diseases are summarized, thus bringing together some of the latest information available on the pathogenetic role of oxidative stress in cancer. The authors evaluate the most recent publications on this topic, and, in particular, show the newest evidence of a relationship between oxidative stress and hematological malignancies, such as chronic lymphocytic leukemia, Hodgkin's lymphoma, multiple myeloma and chronic Ph-negative myeloproliferative diseases. A separate section is devoted to the implications of a change of oxidative stress in patients undergoing bone marrow transplantation. Finally, particular attention is given to the new markers of oxidative stress, such as carbonyl groups, advanced glycation end products, advanced oxidation protein products and S-nitrosylated proteins, which are certainly more stable, reliable, cheaper and more easily identifiable than those already used in clinical practice. New approaches that aim to evaluate subcellular and microenvironment redox potential may be useful in developing cancer diagnostics and therapeutics.

Scavenger receptor class A member 3 (SCARA3) in disease progression and therapy resistance in multiple myeloma

This study evaluates the role of scavenger receptor class A member 3 (SCARA3) in multiple myeloma (MM). SCARA3 expression was induced upon treatment with oxidative stressors (ionizing radiation and chemotherapeutic drugs). An epigenetic inactivation of SCARA3 was noted in MM.1S myeloma cells. Myeloma cell killing by dexamethasone and bortezomib was inhibited by up-regulation of SCARA3 while SCARA3 knockdown sensitized myeloma cells to the drugs. Clinical samples showed an inverse correlation between SCARA3 gene expression, myeloma progression, and favorable clinical prognosis. In MM, SCARA3 protects against oxidative stress-induced cell killing and can serve as predictor of MM progression and therapeutic response.

p70S6 kinase is a target of the novel proteasome inhibitor 3,3'-diamino-4'-methoxyflavone during apoptosis in human myeloid tumor cells

Acute myeloid leukemia (AML) is a deadly disease characterized by the clonal expansion and accumulation of hematopoietic stem cells arrested at various stages of development. Clinical research efforts are currently focusing on targeted therapies that induce apoptosis in AML cells. Herein, the effects and mechanisms of the novel flavone 3,3'-diamino-4'-methoxyflavone (DD1) on AML cell dysfunction were investigated in AML cells (monoblast U937, myelomonocyte OCI-AML3, promyelocyte NB4, myeloblast HL-60) and blood samples from patients with AML. The administration of DD1 inhibited proliferation and induced death of AML cell lines and reduced the clonogenic activity of AML, but not normal, blood cells. The flavone's apoptotic action in U937 cells was associated with recruitment of mitochondria, Bax activation, Bad dephosphorylation (at Ser(136)), activation of caspases -8, -9, and -3 and cleavage of the caspase substrate PARP-1. DD1 induced a marked decrease in (i) Thr(389)-phosphorylation and (ii) protein levels of the caspase-3 substrate P70 ribosomal S6 kinase (P70S6K, known for its ability to phosphorylate Bad). Caspase-dependent apoptosis and P70S6K degradation were simultaneously prevented by the caspase inhibitors. Importantly, DD1 was shown to directly inhibit the proteasome's chymotrypsin-like activity in U937 cells. Apoptotic activity of the proteasome inhibitor bortezomib was also related to Bax activation and P70S6K downregulation. Accordingly, DD1 failed to induce P70S6K cleavage, Bax stimulation and apoptosis in K562 cells resistant to bortezomib. These results indicate that DD1 has the potential to eradicate AML cells and support a critical role for Bax and P70S6K in DD1-mediated proteasome inhibition and apoptosis of leukemia cells.

The metabolic regulator PGC-1α links anti-cancer cytotoxic chemotherapy to reactivation of hepatitis B virus

Patients with chronic hepatitis B virus (HBV) infection are at an increased risk for a severe and a potentially fatal viral reactivation following anti-cancer therapy. The molecular mechanism for this induction of HBV expression is still unclear. Here, we show that treating hepatoma cell line expressing HBV with various anti-cancer cytotoxic agents results in a significant up-regulation of HBV expression. This HBV induction is at the transcriptional level and is time dependent. Interestingly, treating hepatoma cells with anti-cancer cytotoxic agents results in a robust induction of peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α), a metabolic and energy regulator that is normally induced in the liver under starvation conditions and that has been previously shown to strongly coactivate HBV transcription. Most importantly, HBV up-regulation following anti-cancer therapy depends on PGC-1α induction, because PGC-1α knock-down abolishes HBV induction. Finally, pretreatment of HBV-expressing cells with the antioxidant agent N-acetylcysteine attenuates the induction of both PGC-1α and HBV in response to anti-cancer treatment, suggesting that chemotherapy-associated PGC-1α induction is mediated by cellular oxidative stress that ultimately leads to HBV up-regulation. We conclude that cytotoxic anti-cancer chemotherapy has a direct and an immune system-independent effect on HBV gene expression, which is mediated by PGC-1α. Our results attribute to this metabolic regulator an unexpected role in linking anti-cancer treatment to HBV reactivation and make PGC-1α a potential target for future anti-HBV therapy, especially under conditions in which it is robustly induced, such as following anti-cancer treatment.

Combination chemotherapy increases cytotoxicity of multiple myeloma cells by modification of nuclear factor (NF)-κB activity

The nuclear factor (NF)-κB signaling pathway is critical in myeloma cell proliferation, inhibition of apoptosis, and emergence of therapy resistance. The chemotherapeutic drugs, dexamethasone (Dex) and bortezomib (BTZ), are widely used in clinical protocols for multiple myeloma (MM) and inhibit the NF-κB signaling pathway by distinct mechanisms. This study evaluates the efficacy of combination therapy with Dex and BTZ and investigates the mechanistic underpinning of endogenous and therapy-induced NF-κB activation in MM. Human myeloma cells and bone marrow stromal cells (BMSCs) were used in monocultures and cocultures to determine the cytotoxic effects of Dex and/or BTZ. Our results show that combined treatment of Dex with BTZ enhanced direct apoptosis of drug-sensitive and drug-resistant myeloma cells. In the presence of BMSCs, Dex plus BTZ combination inhibited ionizing radiation-induced interleukin 6 secretion from BMSCs and induced myeloma cytotoxicity. Mechanistically, Dex treatment increased IκBα protein and mRNA expression and compensated for BTZ-induced IκBα degradation. Dex plus BTZ combination inhibited basal and therapy-induced NF-κB activity with cytotoxicity in myeloma cells resistant to BTZ. Furthermore, combination therapy downregulated the NF-κB-targeted gene expression of interleukin 6 and manganese superoxide dismutase, which can induce chemo- and radio-resistance in MM. This study provides a mechanistic rationale for combining the NF-κB-targeting drugs Dex and BTZ in myeloma therapy and supports potential combinations of these drugs with radiotherapy and additional chemotherapeutic drugs for clinical benefit in MM.

Interleukin-6 counteracts therapy-induced cellular oxidative stress in multiple myeloma by up-regulating manganese superoxide dismutase

IL (interleukin)-6, an established growth factor for multiple myeloma cells, induces myeloma therapy resistance, but the resistance mechanisms remain unclear. The present study determines the role of IL-6 in re-establishing intracellular redox homoeostasis in the context of myeloma therapy. IL-6 treatment increased myeloma cell resistance to agents that induce oxidative stress, including IR (ionizing radiation) and Dex (dexamethasone). Relative to IR alone, myeloma cells treated with IL-6 plus IR demonstrated reduced annexin/propidium iodide staining, caspase 3 activation, PARP [poly(ADP-ribose) polymerase] cleavage and mitochondrial membrane depolarization with increased clonogenic survival. IL-6 combined with IR or Dex increased early intracellular pro-oxidant levels that were causally related to activation of NF-κB (nuclear factor κB) as determined by the ability of N-acetylcysteine to suppress both pro-oxidant levels and NF-κB activation. In myeloma cells, upon combination with hydrogen peroxide treatment, relative to TNF (tumour necrosis factor)-α, IL-6 induced an early perturbation in reduced glutathione level and increased NF-κB-dependent MnSOD (manganese superoxide dismutase) expression. Furthermore, knockdown of MnSOD suppressed the IL-6-induced myeloma cell resistance to radiation. MitoSOX Red staining showed that IL-6 treatment attenuated late mitochondrial oxidant production in irradiated myeloma cells. The present study provides evidence that increases in MnSOD expression mediate IL-6-induced resistance to Dex and radiation in myeloma cells. The results of the present study indicate that inhibition of antioxidant pathways could enhance myeloma cell responses to radiotherapy and/or chemotherapy.