Deregulated NF-kappaB activity in haematological malignancies

Systematic Review of Chemical Compounds with Immunomodulatory Action Isolated from African Medicinal Plants

A robust, well-functioning immune system is the cornerstone of good health. Various factors may influence the immune system's effectiveness, potentially leading to immune system failure. This review aims to provide an overview of the structure and action of immunomodulators isolated from African medicinal plants. The research was conducted according to PRISMA guidelines. Full-text access research articles published in English up to December 2023, including plant characteristics, isolated phytochemicals, and immuno-modulatory activities, were screened. The chemical structures of the isolated compounds were generated using ChemDraw® (version 12.0.1076), and convergent and distinctive signaling pathways were highlighted. These phytochemicals with demonstrated immunostimulatory activity include alkaloids (berberine, piperine, magnoflorine), polysaccharides (pectin, glucan, acemannan, CALB-4, GMP90-1), glycosides (syringin, cordifolioside, tinocordiside, aucubin), phenolic compounds (ferulic acid, vanillic acid, eupalitin), flavonoids (curcumin, centaurein, kaempferin, luteolin, guajaverin, etc.), terpenoids (oleanolic acid, ursolic acid, betulinic acid, boswellic acids, corosolic acid, nimbidin, andrographolides). These discussed compounds exert their effects through various mechanisms, targeting the modulation of MAPKs, PI3K-Akt, and NF-kB. These mechanisms can support the traditional use of medicinal plants to treat immune-related diseases. The outcomes of this overview are to provoke structural action optimization, to orient research on particular natural chemicals for managing inflammatory, infectious diseases and cancers, or to boost vaccine immunogenicity.

Role of IL8 in myeloid malignancies

Aberrant overexpression of Interleukin-8 (IL8) has been reported in Myelodysplastic Syndromes (MDS), Acute Myeloid Leukemia (AML), Myeloproliferative Neoplasms (MPNs) and other myeloid malignancies. IL8 (CXCL8) is a CXC chemokine that is secreted by aberrant hematopoietic stem and progenitors as well as other cells in the tumor microenvironment. IL8 can bind to CXCR1/CXCR2 receptors and activate oncogenic signaling pathways, and also increase the recruitment of myeloid derived suppressor cells to the tumor microenvironment. IL8/CXCR1/2 overexpression has been associated with poorer prognosis in MDS and AML and increased bone marrow fibrosis in Myelofibrosis. Preclinical studies have demonstrated benefit of inhibiting the IL8/CXCR1/2 pathways via restricting the growth of leukemic stem cells as well as normalizing the immunosuppressive microenvironment in tumors. Targeting the IL8-CXCR1/2 pathway is a potential therapeutic strategy in myeloid neoplasms and is being evaluated with small molecule inhibitors as well as monoclonal antibodies in ongoing clinical trials. We review the role of IL8 signaling pathway in myeloid cancers and discuss future directions on therapeutic targeting of IL8 in these diseases.

Prognostic and therapeutic significance of XPO1 in T-cell lymphoma

T-cell lymphoma (TCL) is a highly heterogeneous group of invasive non-Hodgkin lymphoma with adverse prognosis and limited treatment options. The relationship between TCL and Exportin-1 (XPO1), a major nuclear export receptor, has not been established yet. We here investigated the prognostic role and therapeutic implication of XPO1 in TCL. We analyzed XPO1 expression in a cohort of 69 TCL tumors and found that XPO1 was over-expressed in 76.8% of TCL and correlated with decreased progression-free survival (PFS) and overall survival (OS). In vitro treatment of TCL cell lines with KPT-8602, the second-generation selective inhibitor of nuclear export (SINE), inhibited XPO1 expression and showed significant anti-proliferative, cell-cycle arrest and pro-apoptotic efficacy. In mechanism, KPT-8602 restored the localization of cytoplasmic FOXO3A, p27, p21, IκBα and PP2A into the nucleus, leading to AKT and NF-κB deactivation. Our data demonstrate for the first time that XPO1 could be an unfavorable prognostic factor for TCL, and provide a rationale for further investigation of the efficacy of KPT-8602 in TCL patients.

Drug Repositioning for the Treatment of Hematologic Disease: Limits, Challenges and Future Perspectives

Drug repositioning is a strategy to identify new uses for approved or investigational drugs that are used off-label outside the scope of the original medical indication. In this review, we report the most relevant studies about drug repositioning in hematology, reporting the signalling pathways and molecular targets of these drugs, and describing the biological mechanisms which are responsible for their anticancer effects. Although the majority of studies on drug repositioning in hematology concern acute myeloid leukemia and multiple myeloma, numerous studies are present in the literature on the possibility of using these drugs also in other hematological diseases, such as acute lymphoblastic leukemia, chronic myeloid leukemia, and lymphomas. Numerous anti-infectious drugs and chemical entities used for the therapy of neurological or endocrine diseases, oral antidiabetics, statins and medications used to treat high blood pressure and heart failure, bisphosphonate and natural substance such as artemisin and curcumin, have found a place in the treatment of hematological diseases. Moreover, several molecules drastically reversed the resistance of the tumor cells to the chemotherapeutic drugs both in vitro and in vivo.

Different roles of Nrf2 and NFKB in the antioxidant imbalance produced by esculetin or quercetin on NB4 leukemia cells

Esculetin (6,7-dihydrocoumarin) and the flavonoid quercetin (3,5,7,3',4' pentahydroxyflavone) are compounds that could change the balance of redox homeostasis. NB4 leukemia cells were treated with 25 μM quercetin for 24 h and with esculetin at either 100 or 500 μM for different times. Quercetin increased the levels of pro-inflammatory NFkB p65 in the nucleus correspondingly reducing them in the cytosol. The levels of NFkB p65 decreased in the nucleus at high esculetin concentration treatments for long times (19 h), concomitantly increasing the levels of anti-inflammatory NFkB p50 in the nucleus. This could suggest formation of inhibitory p50 homodimers possibly related with anti-inflammatory response. Lipoxygenase expression was reduced either by esculetin or quercetin. A significant increase of Nrf2 in the nucleus of NB4 cells treated with 100 μM esculetin for 19 h was observed. Quercetin increased the levels of Nrf2 in the cytosol reducing them in the nucleus. Superoxide dismutase expression increased in NB4 cells treated with esculetin in contrast with quercetin. All these data support a relevant differential role for NFkB and Nrf2 in anti-inflammatory and redox response when apoptosis was induced by esculetin or quercetin in human leukemia NB4 cells.

Drug Repurposing for the Treatment of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the accumulation of immature myeloid progenitor cells in the bone marrow, compromising of normal blood cell production and ultimately resulting in bone marrow failure. With a 20% overall survival rate at 5 years and 50% in the 18- to 65-year-old age group, new medicines are needed. It is proposed that development of repurposed drugs may be a part of the new therapy needed. AML is subdivided into recurrent molecular entities based on molecular genetics increasingly accessible for precision medicine. Novel therapy developments form a basis for novel multimodality therapy and include liposomal daunorubicin/cytarabine, broad or FLT3-specific tyrosine kinase inhibitors, Bcl-2 family inhibitors, selective inhibitors of nuclear export, metabolic inhibitors, and demethylating agents. The use of non-transplant immunotherapy is in early development in AML with the exceptional re-approval of a toxin-conjugated anti-CD33. However, the full potential of small molecule inhibitors and modalities like immunological checkpoint inhibitors, immunostimulatory small molecules, and CAR-T cell therapy is unknown. Some novel therapeutics will certainly benefit AML patient subgroups; however, due to high cost, more affordable alternatives are needed globally. Also the heterogeneity of AML will likely demand a broader repertoire of therapeutic molecules. Drug repurposing or repositioning represent a source for potential therapeutics with well-known toxicity profiles and reasonable prices. This implies that biomarkers of response need to accompany the development of antileukemic therapies for sharply defined patient subgroups. We will illustrate repurposing in AML with selected examples and discuss some experimental and regulatory limitations that may obstruct this development.

Genetic polymorphisms of IL-18 rs1946518 and IL-1β rs16944 are associated with prognosis and survival of acute myeloid leukemia

BACKGROUND

Though the pathogenesis of AML is still unknown, accumulating evidence revealed that immune response plays a vital part in it. NLRP3 inflammasome as a component of immune system has been found related to several cancers. The single nucleotide polymorphisms (SNPs) of NLRP3 inflammasome genes may be related to pathogenesis and prognosis of AML.

METHODS AND RESULTS

We determined polymorphisms of NLRP3 (rs35829419), CARD8 (rs2043211), IL-1β (rs16944), IL-18 (rs1946518) and NF-κB -94 ins/del ATTG in de novo AML patients to find out whether they play roles in the susceptibility and severity of AML. In our study, 383 AML cases and 300 randomly selected healthy individuals were examined for the polymorphisms and expression of NLRP3 genes. IL-1β (rs16944) polymorphism in different risk AML subgroups was found statistically different, with more GA genotype in favorable-risk cytogenetics group. We also demonstrated that the bone marrow blasts of patients carrying IL-18 (rs1946518) GG or GT genotype were higher than patients of TT genotype. IL-18 plasma level of patients with IL-18 (rs1946518) GT or TT genotype was higher than GG genotype. Moreover, the GT genotype of IL-18 (rs1946518) led to statistically poorer AML-specific survival.

CONCLUSION

IL-1β (rs16944) and IL-18 (rs1946518) may be served as potential predictors for AML.

NF-κB signaling as a driver of ageing

NF-κB signaling exerts essential roles in immunity and cellular stress responses, regulating many functions related with organism innate defense. Besides, NF-κB altered signaling has been causally linked to ageing and diverse pathological conditions. We discuss herein the functional involvement of this signaling pathway in ageing, visiting recent experimental evidence about NF-κB activation in this complex process, its functional consequences and the novel biological functions raised from these works. Moreover, we discuss ageing intervention strategies based on NF-κB inhibition, which have demonstrated to be effective at delaying and even reverting different ageing manifestations in human and mouse models of both normal and accelerated ageing. Altogether, the current evidence supports that NF-κB activation constitutes a driving force of the ageing process and a preferential target for rejuvenation-aimed approaches.

Use of deferasirox, an iron chelator, to overcome imatinib resistance of chronic myeloid leukemia cells

BACKGROUND/AIMS

The treatment of chronic myeloid leukemia (CML) has achieved impressive success since the development of the Bcr-Abl tyrosine kinase inhibitor, imatinib mesylate. Nevertheless, resistance to imatinib has been observed, and a substantial number of patients need alternative treatment strategies.

METHODS

We have evaluated the effects of deferasirox, an orally active iron chelator, and imatinib on K562 and KU812 human CML cell lines. Imatinib-resistant CML cell lines were created by exposing cells to gradually increasing concentrations of imatinib.

RESULTS

Co-treatment of cells with deferasirox and imatinib induced a synergistic dose-dependent inhibition of proliferation of both CML cell lines. Cell cycle analysis showed an accumulation of cells in the subG1 phase. Western blot analysis of apoptotic proteins showed that co-treatment with deferasirox and imatinib induced an increased expression of apoptotic proteins. These tendencies were clearly identified in imatinib-resistant CML cell lines. The results also showed that co-treatment with deferasirox and imatinib reduced the expression of BcrAbl, phosphorylated Bcr-Abl, nuclear factor-κB (NF-κB) and β-catenin.

CONCLUSIONS

We observed synergistic effects of deferasirox and imatinib on both imatinib-resistant and imatinib-sensitive cell lines. These effects were due to induction of apoptosis and cell cycle arrest by down-regulated expression of NF-κB and β-catenin levels. Based on these results, we suggest that a combination treatment of deferasirox and imatinib could be considered as an alternative treatment option for imatinib-resistant CML.

NF-κB, an active player in human cancers

NF-κB comprises a family of five transcription factors that form distinct protein complexes, which bind to consensus DNA sequences at promoter regions of responsive genes regulating cellular processes. The past three decades have witnessed remarkable progress in understanding the NF-κB signaling pathway in physiologic and pathologic conditions. The role of NF-κB in human cancer initiation, development, metastasis, and resistance to treatment has drawn particular attention. A significant number of human cancers have constitutive NF-κB activity due to the inflammatory microenvironment and various oncogenic mutations. NF-κB activity not only promotes tumor cells' proliferation, suppresses apoptosis, and attracts angiogenesis, but it also induces epithelial-mesenchymal transition, which facilitates distant metastasis. In certain circumstances, NF-κB activation may also remodel local metabolism and anergize the immune system to favor tumor growth. Suppression of NF-κB in myeloid cells or tumor cells usually leads to tumor regression, which makes the NF-κB pathway a promising therapeutic target. However, because of its vital role in various biologic activities, components of the NF-κB pathway need to be carefully selected and evaluated to design targeted therapies.

Aberrant nuclear factor-kappa B activity in acute myeloid leukemia: from molecular pathogenesis to therapeutic target

The overall survival of patients with acute myeloid leukemia (AML) has not been improved significantly over the last decade. Molecularly targeted agents hold promise to change the therapeutic landscape in AML. The nuclear factor kappa B (NF-κB) controls a plethora of biological process through switching on and off its long list of target genes. In AML, constitutive NF-κB has been detected in 40% of cases and its aberrant activity enable leukemia cells to evade apoptosis and stimulate proliferation. These facts suggest that NF-κB signaling pathway plays a fundamental role in the development of AML and it represents an attractive target for the intervention of AML. This review summarizes our current knowledge of NF-κB signaling transduction including canonical and non-canonical NF-κB pathways. Then we specifically highlight what factors contribute to the aberrant activation of NF-κB activity in AML, followed by an overview of 8 important clinical trials of the first FDA approved proteasome inhibitor, Bortezomib (Velcade), which is a NF-κB inhibitor too, in combination with other therapeutic agents in patients with AML. Finally, this review discusses the future directions of NF-κB inhibitor in treatment of AML, especially in targeting leukemia stem cells (LSCs).

Discovery of novel small-molecule compounds with selective cytotoxicity for Burkitt's lymphoma cells using 3D ligand-based virtual screening

We describe a ligand-based approach towards compounds with more specific targeting for Burkitt's lymphoma. Using three-dimensional ligand-based similarity searches and a previously described hit compound, we have identified six compounds that are chemically different but with similar spatial conformations. Biological evaluation revealed that one compound has better growth inhibition and improved selectivity towards Burkitt's lymphoma cells than the query compound. However, initial mechanism-of-action studies show a different target profile in comparison with the previous hit compound, which does not involve the inhibition of the proteasome or the NFκB pathway. The data from this study provide a solid basis for further efforts in the search for selective agents against Burkitt's lymphoma.

Regulation of p53 and Rb links the alternative NF-κB pathway to EZH2 expression and cell senescence

There are two major pathways leading to induction of NF-κB subunits. The classical (or canonical) pathway typically leads to the induction of RelA or c-Rel containing complexes, and involves the degradation of IκBα in a manner dependent on IκB kinase (IKK) β and the IKK regulatory subunit NEMO. The alternative (or non-canonical) pathway, involves the inducible processing of p100 to p52, leading to the induction of NF-κB2(p52)/RelB containing complexes, and is dependent on IKKα and NF-κB inducing kinase (NIK). Here we demonstrate that in primary human fibroblasts, the alternative NF-κB pathway subunits NF-κB2 and RelB have multiple, but distinct, effects on the expression of key regulators of the cell cycle, reactive oxygen species (ROS) generation and protein stability. Specifically, following siRNA knockdown, quantitative PCR, western blot analyses and chromatin immunoprecipitation (ChIP) show that NF-κB2 regulates the expression of CDK4 and CDK6, while RelB, through the regulation of genes such as PSMA5 and ANAPC1, regulates the stability of p21WAF1 and the tumour suppressor p53. These combine to regulate the activity of the retinoblastoma protein, Rb, leading to induction of polycomb protein EZH2 expression. Moreover, our ChIP analysis demonstrates that EZH2 is also a direct NF-κB target gene. Microarray analysis revealed that in fibroblasts, EZH2 antagonizes a subset of p53 target genes previously associated with the senescent cell phenotype, including DEK and RacGAP1. We show that this pathway provides the major route of crosstalk between the alternative NF-κB pathway and p53, a consequence of which is to suppress cell senescence. Importantly, we find that activation of NF-κB also induces EZH2 expression in CD40L stimulated cells from Chronic Lymphocytic Leukemia patients. We therefore propose that this pathway provides a mechanism through which microenvironment induced NF-κB can inhibit tumor suppressor function and promote tumorigenesis.

Although the classical NF-κB pathway is frequently associated with the induction of cellular senescence and the senescence associated secretory phenotype (SASP), the role of the alternative NF-κB pathway, which is frequently activated in hematological malignancies as well as some solid tumors, has not been defined. We therefore investigated the role of the alternative NF-κB pathway in this process. Here we report that NF-κB2 and RelB, the effectors of the alternative NF-κB pathway, suppress senescence through inhibition of p53 activity. Using primary human fibroblasts, we demonstrate that this is accomplished through NF-κB2/RelB dependent control of a previously unknown pathway, incorporating regulation of CDK4 and 6 expression as well as regulators of p21WAF1 and p53 protein stability. Loss of NF-κB2/RelB results in suppression of retinoblastoma (Rb) tumour suppressor phosphorylation, which in turn leads to inhibition of EZH2 expression and de-repression of p53 activity. Interestingly, we find that CD40 ligand stimulation of cells from Chronic Lymphocytic Leukemia patients, which strongly induces the alternative NF-κB pathway, also induces EZH2 expression. We propose that the alternative NF-κB pathway can promote tumorigenesis through suppression of p53 dependent senescence, a process that may have relevance to cancer cells retaining wild type p53.

Increased frequency of Mediterranean fever gene variants in multiple myeloma

High frequencies of inherited variants in the Mediterranean fever (MEFV) gene have been identified in patients with multiple myeloma (MM). The sample size of the present pilot study was small, therefore, the actual frequency of inherited variants in the MEFV gene could be investigated in patients with MM. Twenty-eight patients with MM and 65 healthy controls were included in the study. Six heterozygous and one homozygous (E148Q/E148Q) variant was identified in patients with MM. None of the patients had a family history compatible with familial Mediterranean fever. In the healthy control group, 11 heterozygous variants were identified. The difference in the overall frequency of the inherited variants in the MEFV gene between the MM patients and the controls was statistically significant (χ²=4.905; P=0.027). In conclusion, a high frequency of inherited variants in the MEFV gene was identified in patients with MM. Based on the current data, it is hypothesized that the MEFV gene is a cancer susceptibility gene. Additional evidence, such as familial aggregation, monozygotic versus dizygotic twin concordance, and tumors in genetically engineered model organisms, is required in order to support this hypothesis.

Structural characterization and biological evaluation of a clioquinol–ruthenium complex with copper-independent antileukaemic activity

The organoruthenium clioquinol complex induces copper-independent cell death in leukaemia cells by proteasome-independent inhibition of the NFκB signalling pathway.

Mechanisms of nanoparticle-mediated siRNA transfection by melittin-derived peptides

Traditional peptide-mediated siRNA transfection via peptide transduction domains exhibits limited cytoplasmic delivery of siRNA due to endosomal entrapment. This work overcomes these limitations with the use of membrane-destabilizing peptides derived from melittin for the knockdown of NFkB signaling in a model of adult T-cell leukemia/lymphoma. While the mechanism of siRNA delivery into the cytoplasmic compartment by peptide transduction domains has not been well studied, our analysis of melittin derivatives indicates that concurrent nanocomplex disassembly and peptide-mediated endosomolysis are crucial to siRNA transfection. Importantly, in the case of the most active derivative, p5RHH, this process is initiated by acidic pH, indicating that endosomal acidification after macropinocytosis can trigger siRNA release into the cytoplasm. These data provide general principles regarding nanocomplex response to endocytosis, which may guide the development of peptide/siRNA nanocomplex-based transfection.

A noncanonical NF-κB pathway through the p50 subunit regulates Bcl-2 overexpression during an oxidative-conditioning hormesis response

Cells can respond to damage and stress by activating various repair and survival pathways. One of these responses can be induced by preconditioning the cells with sublethal stress to provoke a prosurvival response that will prevent damage and death, and which is known as hormesis. Bcl-2, an antiapoptotic protein recognized by its antioxidant and prosurvival functions, has been documented to play an important role during oxidative-conditioning hormesis. Using an oxidative-hormetic model, which was previously established in the L929 cell line by subjecting the cells to a mild oxidative stress of 50 μM H₂O₂ for 9 h, we identified two different transductional mechanisms that participate in the regulation of Bcl-2 expression during the hormetic response. These mechanisms converge in activating the nuclear transcription factor NF-κB. Interestingly, the noncanonical p50 subunit of the NF-κB family is apparently the subunit that participates during the oxidative-hormetic response.

High Frequency of Inherited Variants in the MEFV Gene in Acute Lymphocytic Leukemia

In the present study, we aimed to determine the frequency of inherited variants in the MEFV (Mediterranean FeVer), the gene responsible for familial Mediterranean fever (FMF), gene in patients with acute lymphocytic leukemia (ALL). The eight MEFV gene variants (M694I, M694V, M680I (G/C-A), V726A, R761H, E148Q and P369S) were detected in 36 patients with ALL and 65 healthy controls; none had own and/or family history compatible with FMF. We identified 11 heterozygous inherited variants in the MEFV gene in both ALL patients and controls. The mean overall frequency of inherited variants in the MEFV gene rate was higher in ALL patients than healthy controls (P = 0.040). It is interesting to note that M680I/0 is predominant variant in patients with ALL. In addition, E148Q variant frequency was also significantly higher in the patient group than the controls (P = 0.012). In conclusion, overall frequency of inherited variants in the MEFV gene was found to be higher in patients with ALL. Based on the present data, it is difficult to reach a definitive conclusion regarding the possibility that inherited variants in the MEFV gene could represent a causative role in ALL. However, the data of our study may provide some new insights in understanding of individual genetic differences in susceptibility to these neoplasms. Further investigations are needed to determine the actual role of inherited variants in the MEFV gene in pathogenesis of ALL.

Kruppel-like factor 7 overexpression suppresses hematopoietic stem and progenitor cell function

Increased expression of Kruppel-like factor 7 (KLF7) is an independent predictor of poor outcome in pediatric acute lymphoblastic leukemia. The contribution of KLF7 to hematopoiesis has not been previously described. Herein, we characterized the effect on murine hematopoiesis of the loss of KLF7 and enforced expression of KLF7. Long-term multilineage engraftment of Klf7(-/-) cells was comparable with control cells, and self-renewal, as assessed by serial transplantation, was not affected. Enforced expression of KLF7 results in a marked suppression of myeloid progenitor cell growth and a loss of short- and long-term repopulating activity. Interestingly, enforced expression of KLF7, although resulting in multilineage growth suppression that extended to hematopoietic stem cells and common lymphoid progenitors, spared T cells and enhanced the survival of early thymocytes. RNA expression profiling of KLF7-overexpressing hematopoietic progenitors identified several potential target genes mediating these effects. Notably, the known KLF7 target Cdkn1a (p21(Cip1/Waf1)) was not induced by KLF7, and loss of CDKN1A does not rescue the repopulating defect. These results suggest that KLF7 is not required for normal hematopoietic stem and progenitor function, but increased expression, as seen in a subset of lymphoid leukemia, inhibits myeloid cell proliferation and promotes early thymocyte survival.

Selective cytotoxicity of amidinopiperidine based compounds towards Burkitt's lymphoma cells involves proteasome inhibition

Serine proteases have proven to be promising pharmacological targets in contemporary drug discovery for cancer treatment. Since azaphenylalanine-based compounds manifest cytotoxic activity, we have selected serine protease inhibitors designed and synthesized in-house with large hydrophobic naphthalene moiety for screening. The cytotoxic potential of screened molecules was correlated to modifications of R¹ residues. The most cytotoxic were compounds with greater basicity; amidinopiperidines, piperidines and benzamidines. Amidinopiperidine-based compounds exert cytotoxicity in low µM range, with IC₅₀ 18 µM and 22 µM for inhibitors 15 and 16 respectively. These compounds exhibited selective cytotoxicity towards the Burkitt’s lymphoma cells Ramos and Daudi, and proved nontoxic to PMBC, Jurkat and U937. They induce caspase-dependent apoptotic cell death, as demonstrated by the use of a pan-caspase inihibitor, zVADfmk, which was able to rescue Ramos cells from compound(s)-induced apoptosis. We confirm a disruption of the pro-survival pathway in Burkitt’s lymphoma through NFκB inhibition. The accumulation of phosphorylated precursor (p105) and inhibitory (IκB) molecules with no subsequent release of active NFκB implicated the involvement of proteasome. Indeed, we show that the amidinopiperidine-based compounds inhibit all three proteolytical activities of the human 20S proteasome, with the most prominent effect being on the trypsin-like activity. Consistently, treatment of Ramos cells with these compounds led to an increase in ubiquitinated proteins. The amidinopiperidine-based serine protease inhibitors presented are, as selective inducers of apoptosis in Burkitt’s lymphoma cells, promising leads for the development of novel chemotherapeutics.

High frequency of inherited variants in the MEFV gene in patients with hematologic neoplasms: a genetic susceptibility?

Familial Mediterranean fever is an autosomal recessive disease occurring in populations originating from the Mediterranean basin. This autoinflammatory syndrome is caused by mutations in the Mediterranean FeVer (MEFV) gene. MEFV encodes a 781 amino acid protein known as pyrin. Pyrin is an important modulator of apoptosis, inflammation, and cytokine processing. In more recent pilot studies, inherited variant analysis of the MEFV gene in patients with hematologic neoplasm showed an unexpectedly high frequency of these variants in the gene. Here, we summarize the current state of knowledge of the relationship between inherited variants in the MEFV gene and hematologic neoplasms. Although no single underlying defect could be targeted in all hematologic neoplasms, it will be important to fully exploit the mechanisms underlying the neoplasm promoting role of inherited variants in MEFV. However, it is unclear how inherited variants in the MEFV gene are associated with tumor susceptibility or promotion in hematologic neoplasms. Further investigations are needed to determine the actual role of the MEFV gene in pathogenesis of these neoplasms.

Activation of oxidative stress-regulated Bcl-3 suppresses CTCF in corneal epithelial cells

Epigenetic factor CTCF (CCCTC binding factor) plays important roles in genetic controls of the cell fate. Previous studies found in corneal epithelial cells that CTCF is regulated by epidermal growth factor (EGF) through activation of NF-κB p65/p50. It also found that CTCF is suppressed in ultraviolet (UV) stress-induced corneal epithelial cells. However, it is still unknown how UV stress down-regulates CTCF affecting the cell fate. In the present study, we report that regulation of CTCF by extracellular stress signals is dependent upon activations of an oxidative stress-regulated protein Bcl-3. We found that activated Bcl-3 was able to bind to the κB sites identified in the CTCF promoter region. Bcl-3 was activated by UV irradiation to interact with NF-κB p50 by forming a Bcl-3/p50 heterodimer complex. The Bcl-3/p50 complex suppressed CTCF promoter activity to down-regulate CTCF transcription. Unlike the effect of EGF, UV stress-induced Bcl-3 activation suppressed CTCF activity without involving the IκBα and p65 pathway. Thus, results of the study reveal a novel mechanism for regulatory control of CTCF in UV stress-induced human corneal epithelial cells, which requires activation and formation of Bcl-3/p50 complex through a noncanonical NF-κB pathway.

Clinical applications of aptamers and nucleic acid therapeutics in haematological malignancies

Haematological malignancies result from a heterogeneous mix of genetic mutations and chromosome aberrations and translocations. Targeted therapies, such as the anti-CD20 antibody rituximab, or the BCR-ABL1 inhibitor imatinib, have proven to be effective treatments in the management of some of these malignancies, though relapsing or refractory disease is still common. Nucleic acid-based therapies have also entered the clinical arena, providing an alternative, complementary approach. The forerunner of these therapies were the antisense oligonucleotides, but their scope has expanded to include short-interfering RNA (siRNA), microRNA, decoy oligonucleotides and aptamers. These can be used either as mono-therapeutics, in conjunction with current chemotherapy regimens, or in combination with each other to improve therapeutic efficacy. Not only can these nucleic acid-based therapies silence target genes, they also have the potential of restoring gene function. While challenges remain in delivering effective doses of nucleic acid in vivo, these are steadily being met, suggesting an optimistic future in the treatment of haematological malignancies. This review summarizes the application of nucleic acid-based therapeutics, particularly aptamers, in the diagnosis and treatment of haematological malignancies.

Prostaglandin EP4 receptor enhances BCR-induced apoptosis of immature B cells

Prostaglandin E2 (PGE2) is emerging as an important co-modulator of B cell responses. Using a pharmacological approach, we aimed to delineate the role of PGE2 in B cell receptor (BCR) induced apoptosis of immature B cells. Gene and protein expression analyses showed that, of the four PGE2 receptors subtypes, only EP4 receptor is upregulated upon BCR cross-linking, leading to sensitization of WEHI 231 cells towards PGE2 mediated inhibitory effects. EP4 receptor antagonist ONO-AE3-208, was able to completely revert the observed effects of PGE2. The engagement of EP4 receptor promotes BCR-induced G0/G1 arrest of WEHI 231 cells, resulting in enhanced caspase mediated, BCR-induced apoptosis. We addressed, mechanistically, the interplay between BCR and EP4 receptor signaling components. Prostaglandin1-alcohol (Pge1-OH), a selective EP4 receptor agonist inhibits BCR-induced activation of NF-κB by suppression of BCR-induced IκBα phosphorylation. Disruption of prosurvival pathways is a possible mechanism by which PGE2 enhances BCR-induced apoptosis in immature B lymphocytes.

Matrine inhibits matrix metalloproteinase-9 expression and invasion of human hepatocellular carcinoma cells

Matrine is the major active component of the traditional Chinese medicine Sophora flavescens, but the molecular mechanisms of matrine on tumor invasion inhibition remain unclear. The aim of this study is to elucidate the effects of matrine on invasion ability of human hepatocellular carcinoma (HCC) cells, matrix metalloproteinase-9 (MMP-9), and nuclear factor (NF)-kappa B expression. The expression activity of MMP-9 was measured by reverse transcription polymerase chain reaction, Western blot, and gelatin zymography analysis. The expression of NF-kappa B was measured by the Western blot analysis. Matrine significantly inhibited MMP-9 expression of SMMC-7721 cells. NF-kappa B inhibitor PTDC induced a marked reduction in MMP-9 expression, and it suggested that NF-kappa B could play an important role in MMP-9 expression. Furthermore, matrine significantly suppressed NF-kappa B expression and the invasion of SMMC-7721 cells. Our results showed that matrine inhibited MMP-9 expression and the invasion of human HCC cells. The inhibitory effects are partly associated with the downregulation of the NF-kappa B signaling pathway.

Marine antitumor drugs: status, shortfalls and strategies

Cancer is considered as one of the deadliest diseases in the medical field. Apart from the preventive therapies, it is important to find a curative measure which holds no loopholes and acts accurately and precisely to curb cancer. Over the past few decades, there have been advances in this field and there are many antitumor compounds available on the market, which are of natural as well as synthetic origin. Marine chemotherapy is well recognized nowadays and profound development has been achieved by researchers to deal with different molecular pathways of tumors. However, the marine environment has been less explored for the production of safe and novel antitumor compounds. The reason is a number of shortfalls in this field. Though ample reviews cover the importance and applications of various anticancerous compounds from marine natural products, in the present review, we have tried to bring the current status of antitumor research based on marine inhibitors of cancer signaling pathways. In addition, focus has been placed on the shortfalls and probable strategies in the arena of marine antitumor drug discovery.

NF-kappaB/STAT3/PI3K signaling crosstalk in iMyc E mu B lymphoma

Background

Myc is a well known driver of lymphomagenesis, and Myc-activating chromosomal translocation is the recognized hallmark of Burkitt lymphoma, an aggressive form of non-Hodgkin's lymphoma. We developed a model that mimics this translocation event by inserting a mouse Myc cDNA gene into the immunoglobulin heavy chain locus, just upstream of the intronic Eμ enhancer. These mice, designated iMyc^Eμ, readily develop B-cell lymphoma. To study the mechanism of Myc-induced lymphoma, we analyzed signaling pathways in lymphoblastic B-cell lymphomas (LBLs) from iMyc^Eμ mice, and an LBL-derived cell line, iMyc^Eμ-1.

Results

Nuclear factor-κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) were constitutively activated in iMyc^Eμ mice, not only in LBLs but also in the splenic B-lymphocytes of young animals months before tumors developed. Moreover, inhibition of either transcription factor in iMyc^Eμ-1 cells suppressed growth and caused apoptosis, and the abrogation of NF-κB activity reduced DNA binding by both STAT3 and Myc, as well as Myc expression. Inhibition of STAT3 signaling eliminated the activity of both NF-κB and Myc, and resulted in a corresponding decrease in the level of Myc. Thus, in iMyc^Eμ-1 cells NF-κB and STAT3 are co-dependent and can both regulate Myc. Consistent with this, NF-κB and phosphorylated STAT3 were physically associated with one another. In addition, LBLs and iMyc^Eμ-1 cells also showed constitutive AKT phosphorylation. Blocking AKT activation by inhibiting PI3K reduced iMyc^Eμ-1 cell proliferation and caused apoptosis, via downregulation of NF-κB and STAT3 activity and a reduction of Myc levels. Co-treatment with NF-κB, STAT3 or/and PI3K inhibitors led to additive inhibition of iMyc^Eμ-1 cell proliferation, suggesting that these signaling pathways converge.

Conclusions

Our findings support the notion that constitutive activation of NF-κB and STAT3 depends on upstream signaling through PI3K, and that this activation is important for cell survival and proliferation, as well as for maintaining the level of Myc. Together, these data implicate crosstalk among NF-κB, STAT3 and PI3K in the development of iMyc^Eμ B-cell lymphomas.

Anticancer Role of PPARgamma Agonists in Hematological Malignancies Found in the Vasculature, Marrow, and Eyes

The use of targeted cancer therapies in combination with conventional chemotherapeutic agents and/or radiation treatment has increased overall survival of cancer patients. However, longer survival is accompanied by increased incidence of comorbidities due, in part, to drug side effects and toxicities. It is well accepted that inflammation and tumorigenesis are linked. Because peroxisome proliferator-activated receptor (PPAR)-gamma agonists are potent mediators of anti-inflammatory responses, it was a logical extension to examine the role of PPARgamma agonists in the treatment and prevention of cancer. This paper has two objectives: first to highlight the potential uses for PPARgamma agonists in anticancer therapy with special emphasis on their role when used as adjuvant or combined therapy in the treatment of hematological malignancies found in the vasculature, marrow, and eyes, and second, to review the potential role PPARgamma and/or its ligands may have in modulating cancer-associated angiogenesis and tumor-stromal microenvironment crosstalk in bone marrow.

Microarray analysis reveals potential target genes of NF-kappaB2/p52 in LNCaP prostate cancer cells

PURPOSE

Our previous studies showed that NF-kappaB2/p52 is involved in the castration-resistant growth of the androgen-sensitive LNCaP prostate cancer cells. The role of NF-kappaB2/p52 in lymphomagenesis has been studied extensively, but its target genes in other cancers remain unknown. In order to identify genes potentially regulated by p52 in prostate cancer cells, we performed a genome-wide microarray analysis of genes differentially up- or down-regulated by the overexpression of p52 by adenoviral-mediated gene delivery in LNCaP cells.

EXPERIMENTAL DESIGN

Total RNAs from vector control-infected and Adeno-p52-infected LNCaP cells were used to prepare cDNAs, which were hybridized to the Whole Genome Human 44k Microarray chips (Agilent Technologies). Data analysis was performed using GeneSpring and Ingenuity Pathway Analysis software. Validation of microarray results was performed by real-time quantitative RT-PCR and Western blot analyses.

RESULTS

Expression of approximately 130 genes was differentially upregulated by >5-fold, whereas approximately 60 genes were differentially downregulated by >2-fold in p52-expressing LNCaP cells. Pathway analysis revealed that the upregulated genes belong to functional categories like cell growth and proliferation, cellular movement, cell-to-cell signaling and interaction, cancer, cell cycle, etc., whereas the downregulated genes were represented by functional categories like cell movement, antigen presentation, and cell death. Six of the top upregulated genes including annexin A2, PLAU, RND3, Twist2, VEGFC, and CXCL1 were validated by real-time PCR and Western blot analysis.

CONCLUSIONS

This study provides a comprehensive analysis of genes potentially regulated by NF-kappaB2/p52 in the LNCaP prostate cancer cell line and provides a rationale for the induction of castration-resistant growth by p52 in LNCaP cells.

Matrix Metalloproteinase-9 gene induction by a truncated oncogenic NF-kappaB2 protein involves the recruitment of MLL1 and MLL2 H3K4 histone methyltransferase complexes

Constitutive nuclear factor (NF)-kappaB activation in haematological malignancies is caused in several cases by loss of function mutations within the coding sequence of NF-kappaB inhibitory molecules such as IkappaBalpha or p100. Hut-78, a truncated form of p100, constitutively generates p52 and contributes to the development of T-cell lymphomas but the molecular mechanism underlying this oncogenic potential remains unclear. We show here that MMP9 gene expression is induced through the alternative NF-kappaB-activating pathway in fibroblasts and also on Hut-78 or p52 overexpression in fibroblasts as well as in lymphoma cells. p52 is critical for Hut-78-mediated MMP9 gene induction as a Hut-78 mutant as well as other truncated NF-kappaB2 proteins that are not processed into p52 failed to induce the expression of this metalloproteinase. Conversely, MMP9 gene expression is impaired in p52-depleted HUT-78 cells. Interestingly, MLL1 and MLL2 H3K4 methyltransferase complexes are tethered by p52 on the MMP9 but not on the IkappaBalpha promoter, and the H3K4 trimethyltransferase activity recruited on the MMP9 promoter is impaired in p52-depleted HUT-78 cells. Moreover, MLL1 and MLL2 are associated with Hut-78 in a native chromatin-enriched extract. Thus, we identified a molecular mechanism by which the recruitment of a H3K4 histone methyltransferase complex on the promoter of a NF-kappaB-dependent gene induces its expression and potentially the invasive potential of lymphoma cells harbouring constitutive activity of the alternative NF-kappaB-activating pathway.

Is NF-kappaB a good target for cancer therapy? Hopes and pitfalls

Nuclear factor kappaB (NF-kappaB) transcription factors have a key role in many physiological processes such as innate and adaptive immune responses, cell proliferation, cell death, and inflammation. It has become clear that aberrant regulation of NF-kappaB and the signalling pathways that control its activity are involved in cancer development and progression, as well as in resistance to chemotherapy and radiotherapy. This article discusses recent evidence from cancer genetics and cancer genome studies that support the involvement of NF-kappaB in human cancer, particularly in multiple myeloma. The therapeutic potential and benefit of targeting NF-kappaB in cancer, and the possible complications and pitfalls of such an approach, are explored.

Oxidative, multistep activation of the noncanonical NF-kappaB pathway via disulfide Bcl-3/p50 complex

Buthionine sulfoximine (BSO) is a well-known inhibitor of glutathione synthesis, producing slow glutathione (GSH) depletion and oxidative stress; some "responder" cells avoid BSO-induced death by trans-activating the prosurvival protein Bcl-2. Here we show that BSO activates a noncanonical, inhibitory NF-kappaB- and p65-independent NF-kappaB pathway via a multistep process leading to the up-regulation of Bcl-2. The slow BSO-induced GSH depletion allows separation of two redox-related phases, namely, early thiol disequilibrium and late frank oxidative stress; each phase contributes to the progressive activation of a p50-p50 homodimer. The early phase, coinciding with substantial thiol depletion, produces a cytosolic preparative complex, consisting of p50 and its interactor Bcl-3 linked by interprotein disulfide bridges. The late phase, coinciding with reactive oxygen species production, is responsible, probably via p38 activation, for nuclear targeting of the complex and trans-activation of Bcl-2.

ABINs inhibit EGF receptor-mediated NF-kappaB activation and growth of EGF receptor-overexpressing tumour cells

The epidermal growth factor receptor (EGFR) is frequently overexpressed in various tumours of epidermal origin and is held responsible for tumourigenicity and tumour persistence. Increased nuclear factor (NF)-kappaB activity has been suggested to be involved in the malignant behaviour of EGFR-overexpressing cells. However, the mechanisms that regulate EGF-induced NF-kappaB activation are still largely unknown. Here we show that EGF can induce NF-kappaB-dependent gene expression independently from IkappaBalpha degradation or p100 processing in EGFR-overexpressing HEK293T cells. Moreover, EGF-induced NF-kappaB activation could be inhibited by overexpression of ABINs, which were previously identified as intracellular inhibitors of tumour necrosis factor, interleukin-1 and lipopolysaccharide-induced NF-kappaB activation. Knockdown of ABIN-1 by RNA interference boosted the NF-kappaB response upon EGF stimulation. The C-terminal ubiquitin-binding domain containing region of ABINs was crucial and sufficient for NF-kappaB inhibition. Adenoviral gene transfer of ABINs reduced constitutive NF-kappaB activity as well as the proliferation of EGFR-overexpressing A431 and DU145 human carcinoma cells. Altogether, these results demonstrate an important role for an ABIN-sensitive non-classical NF-kappaB signalling pathway in the proliferation of EGFR-overexpressing tumour cells, and indicate a potential use for ABIN gene therapy in the treatment of cancer.

Prevalence of bortezomib-resistant constitutive NF-kappaB activity in mantle cell lymphoma

Background

The proteasome inhibitor bortezomib can inhibit activation of the transcription factor NF-κB, a mechanism implicated in its anti-neoplastic effects observed in mantle cell lymphoma (MCL). However, NF-κB can be activated through many distinct mechanisms, including proteasome independent pathways. While MCL cells have been shown to harbor constitutive NF-κB activity, what fraction of this activity in primary MCL samples is sensitive or resistant to inhibition by bortezomib remains unclear.

Results

Proteasome activity in the EBV-negative MCL cell lines Jeko-1 and Rec-1 is inhibited by greater than 80% after exposure to 20 nM bortezomib for 4 hours. This treatment decreased NF-κB activity in Jeko-1 cells, but failed to do so in Rec-1 cells when assessed by electrophoretic mobility shift assay (EMSA). Concurrently, Rec-1 cells were more resistant to the cytotoxic effects of bortezomib than Jeko-1 cells. Consistent with a proteasome inhibitor resistant pathway of activation described in mouse B-lymphoma cells (WEHI231) and a breast carcinoma cell line (MDA-MB-468), the bortezomib-resistant NF-κB activity in Rec-1 cells is inhibited by calcium chelators, calmodulin inhibitors, and perillyl alcohol, a monoterpene capable of blocking L-type calcium channels. Importantly, the combination of perillyl alcohol and bortezomib is synergistic in eliciting Rec-1 cell cytotoxicity. The relevance of these results is illuminated by the additional finding that a considerable fraction of primary MCL samples (8 out of 10) displayed bortezomib-resistant constitutive NF-κB activity.

Conclusion

Our findings show that bortezomib-resistant NF-κB activity is frequently observed in MCL samples and suggest that this activity may be relevant to MCL biology as well as serve as a potential therapeutic target.