Microenvironmental stromal cells abrogate NF-κB inhibitor-induced apoptosis in chronic lymphocytic leukemia

Oxymatrine induces apoptosis in non-small cell lung cancer cells by downregulating TRIM46

Sophora flavescens Aiton, a traditional Chinese medicine that was supposed to predominantly play an anti-inflammatory role, has been used to treat multiple diseases, including cancer, for over two thousand years. Recently, it has attracted increasing attention due to the anti-tumor properties of Oxymatrine, one of the most active alkaloids extracted from S. flavescens. This study aims to explore it's anti-tumor effects in non-small cell lung cancer (NSCLC) and the underlying mechanisms. We first investigated the effects of oxymatrine on cell apoptosis in lung cancer cell lines A549 and PC9 as well as explored related genes in regulating the apoptosis by transcriptome analysis. Subsequently, to further study the role of TRIM46, we constructed two types of TRIM46 over-expression cells (A549TRIM46+ and PC9TRIM46+ cells) and then investigated the effect of TRIM46 on oxymatrine-induced apoptosis. Moreover, we explored the effect of TRIM46 on downstream signaling pathways. Transcriptome analysis suggested that shared differentially expressed genes (DEGs) in A549 and PC9 cells treated with oxymatrine were CACNA1I, PADI2, and TRIM46. According to TCGA database analysis, the abundance of TRIM46 expression was higher than CACNA1I, and PADI2 in lung cancer tissues, then was selected as the final DEG for subsequent studies. We observed that oxymatrine resulted in down-expression of TRIM46 as well as induced the apoptosis of the cancer cells in a dose- and time-dependent manner. Meanwhile, we found that apoptosis induced by oxymatrine was inhibited by over-expressing TRIM46. Furthermore, our study indicated that the NF-κB signaling pathway was involved in apoptosis suppressed by TRIM46. We conclude that TRIM46 is the direct target of oxymatrine to induce anti-tumor apoptosis and may activate the downstream NF-κB signaling pathway.

Novel Spirocyclic Dimer, SpiD3, Targets Chronic Lymphocytic Leukemia Survival Pathways with Potent Preclinical Effects

Chronic lymphocytic leukemia (CLL) cell survival and growth is fueled by the induction of B-cell receptor (BCR) signaling within the tumor microenvironment (TME) driving activation of NFκB signaling and the unfolded protein response (UPR). Malignant cells have higher basal levels of UPR posing a unique therapeutic window to combat CLL cell growth using pharmacologic agents that induce accumulation of misfolded proteins. Frontline CLL therapeutics that directly target BCR signaling such as Bruton tyrosine kinase (BTK) inhibitors (e.g., ibrutinib) have enhanced patient survival. However, resistance mechanisms wherein tumor cells bypass BTK inhibition through acquired BTK mutations, and/or activation of alternative survival mechanisms have rendered ibrutinib ineffective, imposing the need for novel therapeutics. We evaluated SpiD3, a novel spirocyclic dimer, in CLL cell lines, patient-derived CLL samples, ibrutinib-resistant CLL cells, and in the Eµ-TCL1 mouse model. Our integrated multi-omics and functional analyses revealed BCR signaling, NFκB signaling, and endoplasmic reticulum stress among the top pathways modulated by SpiD3. This was accompanied by marked upregulation of the UPR and inhibition of global protein synthesis in CLL cell lines and patient-derived CLL cells. In ibrutinib-resistant CLL cells, SpiD3 retained its antileukemic effects, mirrored in reduced activation of key proliferative pathways (e.g., PRAS, ERK, MYC). Translationally, we observed reduced tumor burden in SpiD3-treated Eµ-TCL1 mice. Our findings reveal that SpiD3 exploits critical vulnerabilities in CLL cells including NFκB signaling and the UPR, culminating in profound antitumor properties independent of TME stimuli.

SIGNIFICANCE

SpiD3 demonstrates cytotoxicity in CLL partially through inhibition of NFκB signaling independent of tumor-supportive stimuli. By inducing the accumulation of unfolded proteins, SpiD3 activates the UPR and hinders protein synthesis in CLL cells. Overall, SpiD3 exploits critical CLL vulnerabilities (i.e., the NFκB pathway and UPR) highlighting its use in drug-resistant CLL.

NF-kB and the CLL microenvironment

Chronic lymphocytic leukemia (CLL) is the most prevalent type of leukemia in the western world. Despite the positive clinical effects of new targeted therapies, CLL still remains an incurable and refractory disease and resistance to treatments are commonly encountered. The Nuclear Factor-Kappa B (NF-κB) transcription factor has been implicated in the pathology of CLL, with high levels of NF-κB associated with disease progression and drug resistance. This aberrant NF-κB activation can be caused by genetic mutations in the tumor cells and microenvironmental factors, which promote NF-κB signaling. Activation can be induced via two distinct pathways, the canonical and non-canonical pathway, which result in tumor cell proliferation, survival and drug resistance. Therefore, understanding how the CLL microenvironment drives NF-κB activation is important for deciphering how CLL cells evade treatment and may aid the development of novel targeting therapeutics. The CLL microenvironment is comprised of various cells, including nurse like cells, mesenchymal stromal cells, follicular dendritic cells and CD4+ T cells. By activating different receptors, including the B cell receptor and CD40, these cells cause overactivity of the canonical and non-canonical NF-κB pathways. Within this review, we will explore the different components of the CLL microenvironment that drive the NF-κB pathway, investigating how this knowledge is being translated in the development of new therapeutics.

LYN kinase programs stromal fibroblasts to facilitate leukemic survival via regulation of c-JUN and THBS1

Microenvironmental bystander cells are essential for the progression of chronic lymphocytic leukemia (CLL). We have discovered previously that LYN kinase promotes the formation of a microenvironmental niche for CLL. Here we provide mechanistic evidence that LYN regulates the polarization of stromal fibroblasts to support leukemic progression. LYN is overexpressed in fibroblasts of lymph nodes of CLL patients. LYN-deficient stromal cells reduce CLL growth in vivo. LYN-deficient fibroblasts show markedly reduced leukemia feeding capacity in vitro. Multi-omics profiling reveals that LYN regulates the polarization of fibroblasts towards an inflammatory cancer-associated phenotype through modulation of cytokine secretion and extracellular matrix composition. Mechanistically, LYN deletion reduces inflammatory signaling including reduction of c-JUN expression, which in turn augments the expression of Thrombospondin-1, which binds to CD47 thereby impairing CLL viability. Together, our findings suggest that LYN is essential for rewiring fibroblasts towards a leukemia-supportive phenotype.

miRNAs as cornerstones in chronic lymphocytic leukemia pathogenesis and therapeutic resistance- An emphasis on the interaction of signaling pathways

Chronic lymphocytic leukemia (CLL) accounts for the vast majority of cases of leukemia. Patients of advanced age are more likely to develop the condition, which has a highly varied clinical course. Consideration of illness features and preceding treatment sequence, as well as patient preferences and comorbidities, is necessary for selecting the appropriate treatment for the appropriate patient. Therefore, there is an urgent need for novel biomarkers with high sensitivity and specificity to detect CLL early, monitor CLL patients, select the treatment responders, and reduce ineffective treatment, unwanted side effects, and unnecessary expenses. In both homeostasis and illness, microRNAs (miRNAs/miRs) play a vital role as master regulators of gene expression and, by extension, protein expression. MiRNAs typically reduce the stability of mRNAs, including those encoding genes involved in tumorigenesis processes as cell cycle regulation, inflammation, stress response, angiogenesis, differentiation, apoptosis, and invasion. Due to their unique properties, miRNAs are rapidly being exploited as accurate biomarkers for illness detection, and medicines based on miRNA targets are finding widespread application in clinical practice. Accordingly, the current review serves as a quick primer on CLL and the biogenesis of miRNAs. In addition to providing a brief overview of the miRNAs whose function in the progression of CLL has been established by recent in vitro or in vivo research through articulating the influence of these miRNAs on a wide variety of cellular functions, including increased proliferative potential; support for angiogenesis; cell cycle aberration; evasion of apoptosis; promotion of metastasis; and reduced sensitivity to specific treatments.

Pyrrolidine Dithiocarbamate-loaded Electrospun Membranes for Peritendinous Anti-adhesion through Inhibition of the Nuclear Factor-κB Pathway

Peritendinous adhesion is a major cause of limb dysfunction and disability in clinical practice. Numerous studies suggest that activation of nuclear factor-κB (NF-κB) pathway in macrophages could be the pivotal figure in excessive collagen synthesis and thus peritendinous adhesion formation. In this study, we assumed this pathological process could be suppressed by inhibiting NF-κB phosphorylation and nuclear translocation using pyrrolidine dithiocarbamate (PDTC), a specific NF-κB inhibitor with the ability to penetrate cell membranes, in macrophages. Then, we conducted electrospinning process to incorporate PDTC into poly(L-lactic) acid (PLA) electrospinning membranes, that is, the PDTC-PLA membranes. Further, with integral film quality and stable drug release property, the PDTC-PLA membranes were subsequently analyzed in the capability and mechanism of preventing adhesion formation both in vitro and in vivo. Our results showed inhibition of macrophage proliferation as well as NF-κB pathway activation from in vitro assays and outstanding promotion in inhibiting NF-κB p65 phosphorylation and reducing adhesion formation from in vivo assays of PDTC-PLA compared to PLA membranes. In conclusion, our findings suggested that PDTC-PLA as an alternative therapeutic approach alleviated inflammation and peritendinous adhesion formation through NF-κB signaling pathway. STATEMENT OF SIGNIFICANCE: Pyrrolidine dithiocarbamate (PDTC) can be blended into poly-L-lactic acid (PLA) fibrous membranes by electrospinning process. This incorporation of PDTC into PLA is an effective way to inhibit proinflammatory activation of macrophages and to achieve advanced anti-adhesion outcome after tendon repair.

Enhanced Costimulatory Signaling Improves CAR T-cell Effector Responses in CLL

CD19-redirected chimeric antigen receptor (CAR) T cells have shown remarkable activity against B-cell cancers. While second-generation CARs induce complete remission in >80% of patients with acute lymphoblastic leukemia, similar monotherapy induces long-term remissions in only 26% of patients with chronic lymphocytic leukemia (CLL). This disparity is attributed to cell-intrinsic effector defects in autologous CLL-derived T cells. However, the mechanisms by which leukemic cells impact CAR T-cell potency are poorly understood. Herein we describe an in vitro assay that recapitulates endogenous CLL-mediated T-cell defects in healthy donor CAR T cells. Contact with CLL cells insufficiently activates, but does not irreversibly impair, CAR T-cell function. This state is rescuable by strong antigenic stimulation or IL2, and is not driven by immune suppression. Rather, this activation defect is attributable to low levels of costimulatory molecules on CLL cells, and exogenous costimulation enhanced CAR T-cell activation. We next assessed the stimulatory phenotype of CLL cells derived from different niches within the same patient. Lymph node (LN)-derived CLL cells had a strong costimulatory phenotype and promoted better CAR T-cell degranulation and cytokine production than matched peripheral blood CLL cells. Finally, in vitro CD40L-activated CLL cells acquired a costimulatory phenotype similar to the LN-derived tumor and stimulated improved CAR T-cell proliferation, cytokine production, and cytotoxicity. Together, these data identify insufficient activation as a driver of poor CAR T-cell responses in CLL. The costimulatory phenotype of CLL cells drives differential CAR T-cell responses, and can be augmented by improving costimulatory signaling.

Significance

CLL cells insufficiently activate CAR T cells, driven by low levels of costimulatory molecules on the tumor. LN-derived CLL cells are more costimulatory and mediate enhanced CAR T-cell killing. This costimulatory phenotype can be modeled via CD40 L activation, and the activated tumor promotes stronger CAR T-cell responses.

In Vitro and In Vivo Modeling of Normal and Leukemic Bone Marrow Niches: Cellular Senescence Contribution to Leukemia Induction and Progression

Cellular senescence is recognized as a dynamic process in which cells evolve and adapt in a context dependent manner; consequently, senescent cells can exert both beneficial and deleterious effects on their surroundings. Specifically, senescent mesenchymal stromal cells (MSC) in the bone marrow (BM) have been linked to the generation of a supporting microenvironment that enhances malignant cell survival. However, the study of MSC’s senescence role in leukemia development has been straitened not only by the availability of suitable models that faithfully reflect the structural complexity and biological diversity of the events triggered in the BM, but also by the lack of a universal, standardized method to measure senescence. Despite these constraints, two- and three dimensional in vitro models have been continuously improved in terms of cell culture techniques, support materials and analysis methods; in addition, research on animal models tends to focus on the development of techniques that allow tracking leukemic and senescent cells in the living organism, as well as to modify the available mice strains to generate individuals that mimic human BM characteristics. Here, we present the main advances in leukemic niche modeling, discussing advantages and limitations of the different systems, focusing on the contribution of senescent MSC to leukemia progression.

Carfilzomib Enhances the Suppressive Effect of Ruxolitinib in Myelofibrosis

As the first FDA-approved tyrosine kinase inhibitor for treatment of patients with myelofibrosis (MF), ruxolitinib improves clinical symptoms but does not lead to eradication of the disease or significant reduction of the mutated allele burden. The resistance of MF clones against the suppressive action of ruxolitinib may be due to intrinsic or extrinsic mechanisms leading to activity of additional pro-survival genes or signalling pathways that function independently of JAK2/STAT5. To identify alternative therapeutic targets, we applied a pooled-shRNA library targeting ~5000 genes to a JAK2^V617F-positive cell line under a variety of conditions, including absence or presence of ruxolitinib and in the presence of a bone marrow microenvironment-like culture medium. We identified several proteasomal gene family members as essential to HEL cell survival. The importance of these genes was validated in MF cells using the proteasomal inhibitor carfilzomib, which also enhanced lethality in combination with ruxolitinib. We also showed that proteasome gene expression is reduced by ruxolitinib in MF CD34⁺ cells and that additional targeting of proteasomal activity by carfilzomib enhances the inhibitory action of ruxolitinib in vitro. Hence, this study suggests a potential role for proteasome inhibitors in combination with ruxolitinib for management of MF patients.

Sensitization to Drug Treatment in Precursor B-Cell Acute Lymphoblastic Leukemia Is Not Achieved by Stromal NF-κB Inhibition of Cell Adhesion but by Stromal PKC-Dependent Inhibition of ABC Transporters Activity

Cell adhesion to stromal support and the associated intracellular signaling are central to drug resistance, therefore blocking both has been effective in increasing drug sensitization in leukemia. The stromal Ser/Thr protein kinase C (PKC) has been found to be important for conferring protection to leukemic cells. We aimed at elucidating the intracellular signals connected to cell adhesion and to stromal PKC. We found that NF-κB and Akt were up-regulated in mesenchymal stem cells (MSC) after binding of B-cell acute lymphoblastic leukemia (B-ALL) cells. Nevertheless, Akt inhibition did not induce B-ALL cell detachment. In spite of a clear activation of the NF-κB signaling pathway after B-ALL cell binding (up-regulation NF-κB1/2, and down-regulation of the IKBε and IKBα inhibitors) and an important reduction in cell adhesion after NF-κB inhibition, sensitization to the drug treatment was not observed. This was opposite to the PKC inhibitors Enzastaurin and HKPS, a novel chimeric peptide inhibitor, that were able to increase sensitization to dexamethasone, methotrexate, and vincristine. PLCγ1, Erk1/2, and CREB appear to be related to PKC signaling and PKC effect on drug sensitization since they were contra-regulated by HKPS when compared to dexamethasone-treated cells. Additionally, PKC inhibition by HKPS, but not by Enzastaurin, in MSC reduced the activity of three ABC transporters in leukemic cells treated with dexamethasone, a new indirect mechanism to increase sensitization to drug treatment in B-ALL cells. Our results show the validity of targeting the functional characteristic acquired and modulated during cell-to-cell interactions occurring in the leukemic niche.

Syngeneic leukemia models using lentiviral transgenics

Animal models are necessary to study cancer and develop treatments. After decades of intensive research, effective treatments are available for only a few types of leukemia, while others are currently incurable. Our goal was to generate novel leukemia models in immunocompetent mice. We had achieved abilities for overexpression of multiple driving oncogenes simultaneously in normal primary cells, which can be transplanted and followed in vivo. Our experiments demonstrated the induction of primary malignant growth. Leukemia lines that model various types of leukemia, such as acute myeloid leukemia (AML) or chronic lymphocytic leukemia (CLL), were passaged robustly in congenic wild-type immunocompetent mice. These novel leukemia lines, which may complement previous models, offer the flexibility to generate tailored models of defined oncogenes of interest. The characterization of our leukemia models in immunocompetent animals can uncover the mechanisms of malignancy progression and offer a unique opportunity to stringently test anti-cancer chemotherapies.

NF-кB inhibition by DHMEQ: in vitro antiproliferative effects on pilocytic astrocytoma and concise review of the current literature

INTRODUCTION

Pilocytic astrocytoma (PA) is the most common brain tumor that affects the pediatric population. Even though PA is benign and treatment only involves surgery, recurrent or unresectable tumors require chemo- and radiotherapy. Besides BRAF, CDKN2A, or IDH mutations, the hyperactivation of the nuclear factor NF-κB contributes to tumor growth and survival.

METHODS

In the present study, we used publicly available data for the in silico analysis of NF-κB subunits (RELA, RELB, REL, NF-κB1, and NF-κB2) expression in PA samples. Besides, in vitro assays were performed to evaluate proliferation, migration, cell death, on the PA cell line Res286 comparing to human primary astrocytes. Sensitization to radiation therapy and temozolomide (TMZ) was also assayed.

RESULTS

Our results showed that all the members of the NF-kB family are upregulated in PA datasets compared to normal brain tissues. Moreover, DHMEQ treatment significantly reduced cell growth and motility, while sensitized cells to ionizing radiation and TMZ, as previously seen in high-grade gliomas.

CONCLUSIONS

This drug presents a potential application in clinical practice for the treatment of recurrent or inoperable PA. Moreover, its use might assist adjuvant chemotherapy and reduce irradiation doses to avoid toxicity to the surrounding tissues.

Non-Coding RNAs as Cancer Hallmarks in Chronic Lymphocytic Leukemia

The discovery of non-coding RNAs (ncRNAs) and their role in tumor onset and progression has revolutionized the way scientists and clinicians study cancers. This discovery opened new layers of complexity in understanding the fine-tuned regulation of cellular processes leading to cancer. NcRNAs represent a heterogeneous group of transcripts, ranging from a few base pairs to several kilobases, that are able to regulate gene networks and intracellular pathways by interacting with DNA, transcripts or proteins. Deregulation of ncRNAs impinge on several cellular responses and can play a major role in each single hallmark of cancer. This review will focus on the most important short and long non-coding RNAs in chronic lymphocytic leukemia (CLL), highlighting their implications as potential biomarkers and therapeutic targets as they relate to the well-established hallmarks of cancer. The key molecular events in the onset of CLL will be contextualized, taking into account the role of the "dark matter" of the genome.

Next-generation CAR T cells to overcome current drawbacks

As a rapidly emerging treatment in the oncology field, adoptive transfer of autologous, genetically modified chimeric antigen receptor (CAR) T cells has shown striking efficacy and is curative in certain relapsed/refractory patients with hematologic malignancy. This treatment modality of using a "living drug" offers many tantalizing and novel therapeutic strategies for cancer patients whose remaining treatment options may have otherwise been limited. Despite the early success of CAR T cells in hematologic malignancies, many barriers remain for widespread adoption. General barriers include cellular manufacturing limitations, baseline quality of the T cells, adverse events post-infusion such as cytokine release syndrome (CRS) and neurotoxicity, and host rejection of non-human CARs. Additionally, each hematologic disease presents unique mechanisms of relapse which have to be addressed in future clinical trials if we are to augment the efficacy of CAR T treatment. In this review, we will describe current barriers to hindering efficacy of CAR T-cell treatment for hematologic malignancies in a disease-specific manner and review recent innovations aimed at enhancing the potency and applicability of CAR T cells, with the overall goal of building a framework to begin incorporating this form of therapy into the standard medical management of blood cancers.

Role of nuclear factor-kappa B in feline injection site sarcoma

Background

Chronic inflammation has been implicated in sarcomagenesis. Among various factors, activation of nuclear factor-kappa B (NF-κB) signaling pathway has been documented being able to target genes associated with tumor progression and up-regulate the expression of tumor-promoting cytokines and survival genes in several human solid tumors. Feline injection sites sarcomas (FISS) are malignant entities derived from the mesenchymal origin. The disease has been considered to be associated with vaccine adjuvant, aluminum, which serves as a stimulus continuously inducing overzealous inflammatory and immunologic reactions. To understand the contribution of NF-κB in FISS, detection of activated NF-κB in paraffin-embedded specimens, in vitro establishment of primary cells derived from FISS, and evaluation of the effects of the NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), on primary tumor cells were conducted.

Results

In this study, nuclear expression of NF-κB p65 was detected in 83.3% of FISS cases and not correlated with tumor grading, sex, and age. Primary cells derived from FISS in three cats exhibiting same immunohistochemical characteristics as their original tumor were successfully established. The NF-κB inhibitor, DHMEQ, was able to prevent nuclear translocation of NF-κB p65, inhibit cell proliferation, migration, and colonization in dosage-dependent manners, and induce cell apoptosis in these primary FISS cells.

Conclusions

High expression rate of nuclear NF-κB p65 in FISS cases and dose-dependent inhibitory effects on the growth of FISS primary cells treated with NF-κB inhibitor suggested that NF-κB might be a potential molecular therapeutic target for FISS.

Phospholipase C inhibits apoptosis of porcine primary granulosa cells cultured in vitro

Phospholipase C (PLC) can participate in cell proliferation, differentiation and aging. However, whether it has a function in apoptosis in porcine primary granulosa cells is largely uncertain. The objective of this study was to examine the effects of PLC on apoptosis of porcine primary granulosa cells cultured in vitro. The mRNA expression of BAK, BAX and CASP3, were upregulated in the cells treated with U73122 (the PLC inhibitor). The abundance of BCL2 mRNA, was upregulated, while BAX and CASP3 mRNA expression was decreased after treatment with m-3M3FBS (the PLC activator). Both the early and late apoptosis rate were maximized with 0.5 μM U73122 for 4 h. The rate of early apoptosis was the highest at 4 h and the rate of late apoptosis was the highest at 12 h in the m-3M3FBS group. The protein abundance of PLCβ1, protein kinase C β (PKCβ), calmodulin-dependent protein kinaseII α (CAMKIIα) and calcineurinA (CalnA) were decreased by U73122, and CAMKIIα protein abundance was increased by m-3M3FBS. The mRNA expression of several downstream genes (CDC42, NFATc1, and NFκB) was upregulated by PLC. Our results demonstrated that apoptosis can be inhibited by altering PLC signaling in porcine primary granulosa cells cultured in vitro, and several calcium^-sensitive targets and several downstream genes might take part in the processes.

Bioactivity and modulatory functions of Napoleona vogelii on oxidative stress-induced micronuclei and apoptotic biomarkers in mice

Napoleona vogelii is used in traditional medicine for the management of pain, inflammatory conditions and cancer. This study was conducted to investigate the modulatory mechanisms of methanol stem bark extract of N. vogelii on induction of micronuclei, apoptotic biomarkers and in vivo antioxidant enzymes in mice. Forty male albino mice were randomly divided into eight groups (n = 5) and were administered distilled water (DW, 5 mL/kg) as negative control, 100, 200 or 400 mg/kg of the extract respectively for 28 days before the injection of cyclophosphamide (CP, 40 mg/kg) i.p. on the 28th day. The remaining groups were administered 100, 200 or 400 mg/kg of the extract only for 28 days. Twenty four hours after injection of CP or administration of the last dose of extract, animals were euthanized by cervical dislocation and blood samples collected for determination of in vivo antioxidants, the spleen harvested for immunohistochemical expression of NFκB, Bcl-2, Bax and p53. Bone marrow smears were also made for the micronucleus assay. Treatment with the extract resulted in a significant (p < 0.0001) reduction in frequency of micronucleated polychromatic erythrocytes (MNPCEs) compared to CP exposed control conferring protection of 75.09, 94.74 and 96.84% at 100, 200 or 400 mg/kg respectively. In extract and CP exposed animals, there were significant (p < 0.05) increases in GSH, GST and SOD with a corresponding significant (p < 0.05) reduction in MDA. In addition, the extract significantly downregulated cytoplasmic levels of NFκB and Bcl-2 and upregulated Bax and p53. These findings demonstrate that N. vogelli may serve as an interesting lead for chemo-preventive drug development.

Melatonin inhibits MLL-rearranged leukemia via RBFOX3/hTERT and NF-κB/COX-2 signaling pathways

MLL-rearranged leukemia is an aggressive malignancy associated with poor outcome, which is refractory to conventional treatment. Melatonin has been proven to exert anti-tumor activity, but the effect of melatonin on MLL-r leukemia and the underlying mechanism remain poorly understood. In this study, melatonin inhibited cell proliferation and induced apoptosis by activating the caspase-dependent apoptotic pathway in MLL-r leukemia cells. Mechanistic investigations revealed that melatonin suppressed the expression of hTERT by abrogating the binding activity of RBFOX3 to the hTERT promoter. Melatonin also blocked NF-κB nuclear translocation and suppressed NF-κB binding to the COX-2 promoter, thereby suppressing the expression of COX-2. In addition, clinical samples revealed that melatonin exerts anti-leukemic activity in primary MLL-r leukemia blasts ex vivo. In vivo, the mice treated with melatonin experienced a larger reduction in leukemic burden than the control group in a MLL-r leukemia xenograft mouse model. Collectively, these results suggest that melatonin inhibits MLL-rearranged leukemia through suppressing the RBFOX3/hTERT and NF-κB/COX-2 signaling pathways. Our findings provide new insights into the role of melatonin for MLL-r leukemia treatment.

Bendamustine alone or with rituximab modifies expression of apoptosis-regulating genes and proteins of CLL cells, depending on IGVH mutational status

We studied whether bendamustine (BENDA) alone or with rituximab (RIT) modifies in vitro expression of apoptosis-involved genes and proteins of chronic lymphocytic leukemia (CLL) cells depending on IGVH mutational status. Circulating lymphocytes from 34 untreated patients (18 IGVH-MUT and 16 IGVH-UNMUT) were incubated with above drugs to evaluate proteins expression. Microarray analysis of 93 genes was performed in 14 patients. BENDA and BENDA + RIT increased expression of BAX and BBC3 in IGVH-MUT and IGVH-UNMUT groups, and significant differences in expression of above genes after BENDA + RIT were observed between both groups. Additionally, BENDA + RIT decreased NFκB and BCL-2 genes in IGVH-UNMUT patients and increased expression of P53, BAX and PUMA proteins in IGVH-MUT and UNMUT subjects. However, no significant differences were found between these groups. In conclusion, BENDA + RIT modified gene expression profile in CLL cells and affected expression of some apoptosis-regulating proteins in vitro. Expression of BAX and BBC3 depends on action of drugs and IGVH mutational status.