STAT3 and NF-κB cooperatively control in vitro spontaneous apoptosis and poor chemo-responsiveness in patients with chronic lymphocytic leukemia

Inhibition of bromodomain and extra-terminal proteins targets constitutively active NFκB and STAT signaling in lymphoma and influences the expression of the antiapoptotic proteins BCL2A1 and c-MYC

The antiapoptotic protein BCL2A1 is highly, but very heterogeneously expressed in Diffuse Large B-cell Lymphoma (DLBCL). Particularly in the context of resistance to current therapies, BCL2A1 appears to play an important role in protecting cancer cells from the induction of cell death. Reducing BCL2A1 levels may have therapeutic potential, however, no specific inhibitor is currently available. In this study, we hypothesized that the signaling network regulated by epigenetic readers may regulate the transcription of BCL2A1 and hence that inhibition of Bromodomain and Extra-Terminal (BET) proteins may reduce BCL2A1 expression thus leading to cell death in DLBCL cell lines. We found that the mechanisms of action of acetyl-lysine competitive BET inhibitors are different from those of proteolysis targeting chimeras (PROTACs) that induce the degradation of BET proteins. Both classes of BETi reduced the expression of BCL2A1 which coincided with a marked downregulation of c-MYC. Mechanistically, BET inhibition attenuated the constitutively active canonical nuclear factor kappa-light-chain-enhancer of activated B-cells (NFκB) signaling pathway and inhibited p65 activation. Furthermore, signal transducer of activated transcription (STAT) signaling was reduced by inhibiting BET proteins, targeting another pathway that is often constitutively active in DLBCL. Both pathways were also inhibited by the IκB kinase inhibitor TPCA-1, resulting in decreased BCL2A1 and c-MYC expression. Taken together, our study highlights a novel complex regulatory network that links BET proteins to both NFκB and STAT survival signaling pathways controlling both BCL2A1 and c-MYC expression in DLBCL.

Interaction of NF-κB and FOSL1 drives glioma stemness

Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumor; GBM's inevitable recurrence suggests that glioblastoma stem cells (GSC) allow these tumors to persist. Our previous work showed that FOSL1, transactivated by the STAT3 gene, functions as a tumorigenic gene in glioma pathogenesis and acts as a diagnostic marker and potential drug target in glioma patients. Accumulating evidence shows that STAT3 and NF-κB cooperate to promote the development and progression of various cancers. The link between STAT3 and NF-κB suggests that NF-κB can also transcriptionally regulate FOSL1 and contribute to gliomagenesis. To investigate downstream molecules of FOSL1, we analyzed the transcriptome after overexpressing FOSL1 in a PDX-L14 line characterized by deficient FOSL1 expression. We then conducted immunohistochemical staining for FOSL1 and NF-κB p65 using rabbit polyclonal anti-FOSL1 and NF-κB p65 in glioma tissue microarrays (TMA) derived from 141 glioma patients and 15 healthy individuals. Next, mutants of the human FOSL1 promoter, featuring mutations in essential binding sites for NF-κB were generated using a Q5 site-directed mutagenesis kit. Subsequently, we examined luciferase activity in glioma cells and compared it to the wild-type FOSL1 promoter. Then, we explored the mutual regulation between NF-κB signaling and FOSL1 by modulating the expression of NF-κB or FOSL1. Subsequently, we assessed the activity of FOSL1 and NF-κB. To understand the role of FOSL1 in cell growth and stemness, we conducted a CCK-8 assay and cell cycle analysis, assessing apoptosis and GSC markers, ALDH1, and CD133 under varying FOSL1 expression conditions. Transcriptome analyses of downstream molecules of FOSL1 show that NF-κB signaling pathway is regulated by FOSL1. NF-κB p65 protein expression correlates to the expression of FOSL1 in glioma patients, and both are associated with glioma grades. NF-κB is a crucial transcription factor activating the FOSL1 promoter in glioma cells. Mutual regulation between NF-κB and FOSL1 contributes to glioma tumorigenesis and stemness through promoting G1/S transition and inhibiting apoptosis. Therefore, the FOSL1 molecular pathway is functionally connected to NF-κB activation, enhances stemness, and is indicative that FOSL1 may potentially be a novel GBM drug target.

Non-canonical transcriptional regulation of the poor prognostic factor UGT2B17 in chronic lymphocytic leukemic and normal B cells

BACKGROUND

High expression of the glycosyltransferase UGT2B17 represents an independent adverse prognostic marker in chronic lymphocytic leukemia (CLL). It also constitutes a predictive marker for therapeutic response and a drug resistance mechanism. The key determinants driving expression of the UGT2B17 gene in normal and leukemic B-cells remain undefined. The UGT2B17 transcriptome is complex and is comprised of at least 10 alternative transcripts, identified by previous RNA-sequencing of liver and intestine. We hypothesized that the transcriptional program regulating UGT2B17 in B-lymphocytes is distinct from the canonical expression previously characterized in the liver.

RESULTS

RNA-sequencing and genomics data revealed a specific genomic landscape at the UGT2B17 locus in normal and leukemic B-cells. RNA-sequencing and quantitative PCR data indicated that the UGT2B17 enzyme is solely encoded by alternative transcripts expressed in CLL patient cells and not by the canonical transcript widely expressed in the liver and intestine. Chromatin accessible regions (ATAC-Seq) in CLL cells mapped with alternative promoters and non-coding exons, which may be derived from endogenous retrotransposon elements. By luciferase reporter assays, we identified key cis-regulatory STAT3, RELA and interferon regulatory factor (IRF) binding sequences driving the expression of UGT2B17 in lymphoblastoid and leukemic B-cells. Electrophoretic mobility shift assays and pharmacological inhibition demonstrated key roles for the CLL prosurvival transcription factors STAT3 and NF-κB in the leukemic expression of UGT2B17.

CONCLUSIONS

UGT2B17 expression in B-CLL is driven by key regulators of CLL progression. Our data suggest that a NF-κB/STAT3/IRF/UGT2B17 axis may represent a novel B-cell pathway promoting disease progression and drug resistance.

Paradoxical activation of chronic lymphocytic leukemia cells by ruxolitinib in vitro and in vivo

Introduction

Chronic lymphocytic leukemia (CLL) is characterized by an aberrant cytokine network that can support tumor growth by triggering janus kinase (JAK)/STAT pathways. Targeting cytokine-signaling should then be a rational therapeutic strategy but the JAK inhibitor ruxolitinib failed to control and seemingly accelerated the disease in clinical trials.

Methods

The effect of ruxolitinib on primary human CLL cells was studied in vitro and in vivo.

Results

Ruxolitinib increased phosphorylation of IRAK4, an important toll-like receptor (TLR)- signaling intermediate, in circulating CLL cells in vitro. It also enhanced p38 and NFKB1 phosphorylation while lowering STAT3 phosphorylation in CLL cells activated with TLR-7/8 agonists and IL-2. Among the cytokines made by activated CLL cells, high levels of IL-10 contributed strongly to STAT3 phosphorylation and inhibited TLR7 activity. Ruxolitinib limited TLR-mediated IL10 transcription and markedly reduced IL-10 production in vitro. It also decreased blood levels of IL-10 while increasing TNFα along with phospho-p38 expression and gene sets associated with TLR-activation in CLL cells in vivo. The bruton's tyrosine kinase inhibitor ibrutinib decreased IL-10 production in vitro but, in contrast to ruxolitinib, blocked initial IL10 transcription induced by TLR-signaling in vitro, decreased TNFα production, and deactivates CLL cells in vivo.

Discussion

These findings suggest the possible benefits of inhibiting growth factors with JAK inhibitors in CLL are outweighed by negative effects on potential tumor suppressors such as IL-10 that allow unrestrained activation of NFκB by drivers such as TLRs. Specific inhibition of growth-promoting cytokines with blocking antibodies or infusing suppressive cytokines like IL-10 might be better strategies to manipulate cytokines in CLL.

JAK-STAT signalling shapes the NF-κB response in CLL towards venetoclax sensitivity or resistance via Bcl-XL

Preventing or overcoming resistance to the Bcl-2 inhibitor venetoclax is an emerging unmet clinical need in patients with chronic lymphocytic leukaemia (CLL). The upregulation of anti-apoptotic Bcl-2 members through signalling pathways within the tumor microenvironment appears as a major factor leading to resistance to venetoclax. Previously, we reported that T cells can drive resistance through CD40 and non-canonical NF-κB activation and subsequent Bcl-XL induction. Moreover, the T cell-derived cytokines IL-21 and IL-4 differentially affect Bcl-XL expression and sensitivity to venetoclax via unknown mechanisms. Here, we mechanistically dissected how Bcl-XL is regulated in the context of JAK-STAT signalling in primary CLL. First, we demonstrated a clear antagonistic role of IL-21/STAT3 signalling in the NF-κB-mediated expression of Bcl-XL, whereas IL-4/STAT6 further promoted the expression of Bcl-XL. In comparison, Bfl-1, another NF-κB target, was not differentially affected by either cytokine. Second, STAT3 and STAT6 affected Bcl-XL transcription by binding to its promoter without disrupting the DNA-binding activity of NF-κB. Third, in situ proximity ligation assays (isPLAs) indicated crosstalk between JAK-STAT signalling and NF-κB, in which STAT3 inhibited canonical NF-κB by accelerating nuclear export, and STAT6 promoted non-canonical NF-κB. Finally, NF-κB inducing kinase (NIK) inhibition interrupted the NF-κB/STAT crosstalk and resensitized CLL cells to venetoclax. In conclusion, we uncovered distinct crosstalk mechanisms that shape the NF-κB response in CLL towards venetoclax sensitivity or resistance via Bcl-XL, thereby revealing new potential therapeutic targets.

Diacerein attenuate LPS-induced acute lung injury via inhibiting ER stress and apoptosis: Impact on the crosstalk between SphK1/S1P, TLR4/NFκB/STAT3, and NLRP3/IL-1β signaling pathways

AIMS

Acute lung injury (ALI) is a life-threatening clinical problem with high mortality rate and limited treatments or preventive options that represents a major challenge for clinicians. Diacerein (DIA) is a multi-target anthraquinone derivative with potent anti-inflammatory action. The aim of this study is to assess the protective effect of DIA and its potential molecular targets against lipopolysaccharide (LPS)-induced ALI in rats.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were orally administrated DIA (50 mg/kg) for 5 consecutive days followed by a single intraperitoneal injection of LPS (5mg/kg).

KEY FINDINGS

DIA mitigated oxidative lung injury in LPS-challenged rats via significantly decreasing lung wet/dry (W/D) ratio, inflammatory cells infiltration, and lipid peroxidation, with concomitant elevation in enzymatic and non-enzymatic antioxidant levels in lung tissue. Likewise, DIA alleviated endoplasmic reticulum stress and markedly halted inflammation triggered by LPS challenge in pulmonary tissue by suppressing NLRP3/IL-1β and TLR4/NF-κB signaling with parallel decrease in proinflammatory cytokine levels. Interestingly, DIA down regulated Sphk1/S1P axis, reduced GSK-3β and STAT3 proteins expression, and markedly decreased caspase-3 besides increasing Bcl-2 levels in lung tissue of LPS-challenged animals. These biochemical findings was simultaneously associated with marked improvement in histological alterations of lung tissue.

SIGNIFICANCE

These findings verify the protective effect of DIA against LPS-induced ALI through targeting oxidative stress, endoplasmic reticulum stress, and apoptosis. Importantly, DIA halted the hyperinflammatory state triggered by LPS via multi-faceted inhibitory effect on different signaling pathways, hence DIA could potentially reduce mortality in patients with ALI.

Regulation of S100As Expression by Inflammatory Cytokines in Chronic Lymphocytic Leukemia

The calcium-binding proteins S100A4, S100A8, and S100A9 are upregulated in chronic lymphocytic leukemia (CLL), while the S100A9 promotes NF-κB activity during disease progression. The S100-protein family has been involved in several malignancies as mediators of inflammation and proliferation. The hypothesis of our study is that S100A proteins are mediators in signaling pathways associated with inflammation-induced proliferation, such as NF-κB, PI3K/AKT, and JAK/STAT. The mononuclear cells (MNCs) of CLL were treated with proinflammatory IL-6, anti-inflammatory IL-10 cytokines, inhibitors of JAK1/2, NF-κB, and PI3K signaling pathways, to evaluate S100A4, S100A8, S100A9, and S100A12 expression as well as NF-κB activation by qRT-PCR, immunocytochemistry, and immunoblotting. The quantity of S100A4, S100A8, and S100A9 positive cells (p < 0.05) and their protein expression (p < 0.01) were significantly decreased in MNCs of CLL patients compared to healthy controls. The S100A levels were generally increased in CD19+ cells compared to MNCs of CLL. The S100A4 gene expression was significantly stimulated (p < 0.05) by the inhibition of the PI3K/AKT signaling pathway in MNCs. IL-6 stimulated S100A4 and S100A8 protein expression, prevented by the NF-κB and JAK1/2 inhibitors. In contrast, IL-10 reduced S100A8, S100A9, and S100A12 protein expressions in MNCs of CLL. Moreover, IL-10 inhibited activation of NF-κB signaling (4-fold, p < 0.05). In conclusion, inflammation stimulated the S100A protein expression mediated via the proliferation-related signaling and balanced by the cytokines in CLL.

Linoleic acid reduces apoptosis via NF-κB during the in vitro development of induced parthenogenic porcine embryos

Fatty acid has a various role in preimplantation embryo development. Especially, Linoleic acid, polyunsaturated fatty acid, has been reported to affect the apoptosis pathway via nuclear transcription factor-kappa B. But to date, the function of NF-κB has not been demonstrated in porcine preimplantation embryos. We demonstrated that linoleic acid had a positive effect on embryo development at a certain concentration(25 μM), but developmental failure was observed at higher concentration. Furthermore, the expression level of NF-κB increased, unlike that of IL-6, as the concentration of linoleic acid increased. Interestingly, the concentration of NF-κB was found to increase even at the concentration of linoleic acid at which embryo development decreased. We found that pro-apoptotic gene expression was downregulated in the linoleic acid-treated group. It was also found that MCL-1, an anti-apoptotic gene known to be unaffected by IL-6, was found to be increased at the mRNA level in the linoleic acid-treated group. As the concentration of NF-kB increased, the nuclear translocation of C-JUN gradually increased dependent on the linoleic acid concentration. It was confirmed that NF-κB is an important factor in porcine embryos by treated ammonium pyrrolidinedithiocarbamate (APDC 0.1 μM, an inhibitor of NF-κB) affected NF-κB protein expression, IL-6 expression, and blastocyst production. These data supported porcine embryos can use exogenous linoleic acid as a metabolic energy source via NF-κB.

Drug Resistance and Endoplasmic Reticulum Stress in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and deadly cancers worldwide. It is usually diagnosed in an advanced stage and is characterized by a high intrinsic drug resistance, leading to limited chemotherapeutic efficacy and relapse after treatment. There is therefore a vast need for understanding underlying mechanisms that contribute to drug resistance and for developing therapeutic strategies that would overcome this. The rapid proliferation of tumor cells, in combination with a highly inflammatory microenvironment, causes a chronic increase of protein synthesis in different hepatic cell populations. This leads to an intensified demand of protein folding, which inevitably causes an accumulation of misfolded or unfolded proteins in the lumen of the endoplasmic reticulum (ER). This process is called ER stress and triggers the unfolded protein response (UPR) in order to restore protein synthesis or—in the case of severe or prolonged ER stress—to induce cell death. Interestingly, the three different arms of the ER stress signaling pathways have been shown to drive chemoresistance in several tumors and could therefore form a promising therapeutic target. This review provides an overview of how ER stress and activation of the UPR contributes to drug resistance in HCC.

NF-kB-dependent activation of STAT3 by H. pylori is suppressed by TFF1

BACKGROUND

H. pylori infection is the main risk factor for gastric cancer. In this study, we investigated H. pylori-mediated activation of STAT3 and NF-κB in gastric cancer, using in vitro and in vivo models.

METHODS

To investigate the activation of NF-κB and STAT3 by H. pylori strains we used in vitro and in vivo mouse models, western blots, immunofluorescence, ChIP Assay, luciferase and quantitative real-time PCR assays.

RESULTS

Following infection with H. pylori in vitro, we found an earlier phosphorylation of NF-kB-p65 (S536), followed by STAT3 (Y705). Immunofluorescence, using in vitro and in vivo models, demonstrated nuclear localization of NF-kB and STAT3, following H. pylori infection. NF-kB and STAT3 luciferase reporter assays confirmed earlier activation of NF-kB followed by STAT3. In vitro and in vivo models demonstrated induction of mRNA expression of IL-6 (p < 0.001), VEGF-α (p < 0.05), IL-17 (p < 0.001), and IL-23 (p < 0.001). Using ChIP, we confirmed co-binding of both NF-kB-p65 and STAT3 on the IL6 promoter. The reconstitution of Trefoil Factor 1 (TFF1) suppressed activation of NF-kB with reduction in IL6 levels and STAT3 activity, in response to H. pylori infection. Using pharmacologic (BAY11-7082) and genetic (IκB super repressor (IκBSR)) inhibitors of NF-kB-p65, we confirmed the requirement of NF-kB-p65 for activation of STAT3, as measured by phosphorylation, transcription activity, and nuclear localization of STAT3 in in vitro and in vivo models.

CONCLUSION

Our findings suggest the presence of an early autocrine NF-kB-dependent activation of STAT3 in response to H. pylori infection. TFF1 acts as an anti-inflammatory guard against H. pylori-mediated activation of pro-inflammatory networks.

Mining the Microenvironment for Therapeutic Targets in Chronic Lymphocytic Leukemia

ABSTRACT

The leukemia cells of patients with chronic lymphocytic leukemia (CLL) are highly fastidious, requiring stimulation by soluble factors and interactions with accessory cells within the supportive niches of lymphoid tissue that comprise the leukemia microenvironment. The advent of therapies that can disrupt some of the stimulatory signaling afforded by the microenvironment has ushered in a new era of targeted therapy, which has dramatically improved clinical outcome and patient survival. Future advances are required for patients who develop intolerance or resistance to current targeted therapies. These may be found by investigating novel drugs that can inhibit identified targets, such as the pathways involved in B-cell receptor signaling, or by developing agents that inhibit additional targets of the leukemia microenvironment. This review describes some of the molecules involved in promoting the growth and/or survival of CLL cells and discusses targeting strategies that may become tomorrow's therapy for patients with CLL.

Molecular Action of Polyphenols in Leukaemia and Their Therapeutic Potential

Leukaemia is a malignant disease of the blood. Current treatments for leukaemia are associated with serious side-effects. Plant-derived polyphenols have been identified as potent anti-cancer agents and have been shown to work synergistically with standard chemotherapy agents in leukaemia cell lines. Polyphenols have multiple mechanisms of action and have been reported to decrease cell proliferation, arrest cell cycle and induce apoptosis via the activation of caspase (3, 8 and 9); the loss of mitochondrial membrane potential and the release of cytochrome c. Polyphenols have been shown to suppress activation of transcription factors, including NF-kB and STAT3. Furthermore, polyphenols have pro-oxidant properties, with increasing evidence that polyphenols inhibit the antioxidant activity of glutathione, causing oxidative DNA damage. Polyphenols also induce autophagy-driven cancer cell death and regulate multidrug resistance proteins, and thus may be able to reverse resistance to chemotherapy agents. This review examines the molecular mechanism of action of polyphenols and discusses their potential therapeutic targets. Here, we discuss the pharmacological properties of polyphenols, including their anti-inflammatory, antioxidant, anti-proliferative, and anti-tumour activities, and suggest that polyphenols are potent natural agents that can be useful therapeutically; and discuss why data on bioavailability, toxicity and metabolism are essential to evaluate their clinical use.

Deoxycholic Acid Upregulates the Reprogramming Factors KFL4 and OCT4 Through the IL-6/STAT3 Pathway in Esophageal Adenocarcinoma Cells

Cancer stem cells, a special subgroup of cancer cells, have self-renewal capabilities and multidirectional potential, which may be reprogrammed from the dedifferentiation of cancer cells, contributing to the failure of clinical treatments. Esophageal adenocarcinoma grows in an inflammatory environment stimulated by deoxycholic acid, an important component of gastroesophageal reflux content, contributing to the transformation of esophageal squamous epithelium to the precancerous lesions of esophageal adenocarcinoma, that is, Barrett esophagus. In the present study, deoxycholic acid was used to investigate whether it could induce the expression of reprogramming factors Krüppel-like factor, OCT4, and Nanog; the transformation to cancer stem cells in esophageal adenocarcinoma; and the involvement of the interleukin-6/signal transduction and activation of transcription 3 inflammatory signaling pathway. OE33 cells were treated with deoxycholic acid (250 μM) for 0 hour, 3 hours, 6 hours, and 12 hours before evaluating the messenger RNA expression of Krüppel-like factor, OCT4, Nanog, interleukin-6, and Bcl-xL by reverse transcription-quantitative polymerase chain reaction. Interleukin-6 protein was detected by enzyme linked immunosorbent assay, while signal transduction and activation of transcription 3, phosphorylated signal transduction and activation of transcription 3, Krüppel-like factor, and OCT4 were detected by Western blot. Signal transduction and activation of transcription 3 small interfering RNA and human recombinant interleukin-6 were used to treat OE33 cells and to detect their effects on Krüppel-like factor, OCT4, Nanog, CD44, hypoxia-inducible factor 1-α, and Bcl-xL expression. Results showed that deoxycholic acid promotes the expression of reprogramming factors Krüppel-like factor and OCT4, which are regulated by the interleukin-6/signal transduction and activation of transcription 3 signaling pathway. Deoxycholic acid has a malignancy-inducing effect on the transformation of esophageal adenocarcinoma stem cells, improving the antiapoptotic ability of tumors, and increasing the malignancy of esophageal adenocarcinoma. Deactivating the regulatory signaling pathway of interleukin-6/signal transduction and activation of transcription 3 and neutralizing deoxycholic acid may be novel targets for improving the clinical efficacy of esophageal adenocarcinoma therapy.

Cirmtuzumab blocks Wnt5a/ROR1 stimulation of NF-κB to repress autocrine STAT3 activation in chronic lymphocytic leukemia

Coculture of nurse-like cells (NLCs) with chronic lymphocytic leukemia (CLL) cells induced leukemia cell phosphorylation of STAT3 (pSTAT3), which could be blocked by anti-Wnt5a antibodies or the anti-ROR1 monoclonal antibody, cirmtuzumab. Time-course studies revealed Wnt5a could induce activation of NF-κB within 30 minutes, but required more than 3 hours to induce pSTAT3. Culture of isolated CLL cells for 24 hours revealed Wnt5a-induced expression of interleukin 6 (IL-6), IL-8, CCL2, CCL3, CCL4, and CXCL1, which in turn could induce pSTAT3 in unstimulated CLL cells within 30 minutes. We found that Wnt5a could induce CLL cell expression of NF-κB target genes, including IL-6, and that this effect could be blocked by cirmtuzumab or drugs that inhibit NF-κB. Examination of CLL cells and plasma collected from patients treated with cirmtuzumab revealed reduced levels of phosphorylated p65 and diminished expression of NF-κB and STAT3 target genes in CLL cells, as well as lower plasma levels of IL-6, in the samples after therapy. Collectively, these studies indicate that Wnt5a/ROR1-dependent signaling contributes to CLL cell activation of NF-κB, which in turn causes autocrine IL-6-induced activation of pSTAT3. As such, this study demonstrates that cirmtuzumab can inhibit leukemia cell activation of both NF-κB and STAT3 in patients with CLL.

STAT3-induced SMYD3 transcription enhances chronic lymphocytic leukemia cell growth in vitro and in vivo

OBJECTIVE AND DESIGN

The purpose of this study was to investigate the roles of SMYD3 and STAT3 in chronic lymphocytic leukemia (CLL) and the possible underlying mechanisms.

MATERIALS

Blood samples were collected from 20 patients with CLL and 20 hematologically normal donors. Human cell lines K562, HL-60, MEG-1, and BALL-1 were performed in vitro and BALB/c nude mouse was used in subcutaneous tumor experiments.

TREATMENT

WP1066 (30 mg/kg) was also injected intratumorally two days after the first lentivirus treatment and then every four days for a total of four injections and 3 µM WP1066 was carried out for 48 h to downregulate STAT3 phosphorylation.

METHODS

We performed studies using the human CLL cell line MEG-1 in vitro and nude mouse subcutaneous tumor experiments in vivo. Differential expression of RNAs was determined using qRT-PCR. The CCK-8 assay and colony formation assay were conducted to evaluate cell proliferation. Flow cytometry was performed to assess cell apoptosis. The relative protein levels were detected using western blotting. Chromatin immunoprecipitation (ChIP) assays, luciferase reporter assays and WP1066, a STAT3 inhibitor, were used to explore the regulatory mechanisms of proteases and transcription factors. A subcutaneous tumor model was constructed to verify the results in vivo.

RESULTS

SMYD3 and STAT3 expressions positively correlated with the progression of CLL. Upregulation of SMYD3 significantly promoted the proliferation and inhibited the expression of apoptosis-related genes. The results of the ChIP assays and luciferase reporter assays suggested that STAT3 targeted the promoter region of SMYD3 and, thus, promoted SMYD3 transcription. Downregulation of the phosphorylation of STAT3 by WP1066 notably inhibited the binding of STAT3 to the SMYD3 promoter, and subsequently downregulated SMYD3 transcription. The STAT3 inhibitor inhibited CLL cell growth in vivo, and overexpression of SMYD3 promoted CLL cell growth. Furthermore, overexpression of SMYD3 reversed the inhibitory effects of the STAT3 inhibitor on CLL cell growth.

CONCLUSIONS

The STAT3-mediated transcription of SMYD3 plays a role in promoting the progression of chronic lymphocytic leukemia.

Targeting IRAK4 disrupts inflammatory pathways and delays tumor development in chronic lymphocytic leukemia

Interleukin-1 receptor-associated kinase 4 (IRAK4) plays a critical role in Toll-like receptor (TLR) signal transduction and innate immune responses. Recruitment and subsequent activation of IRAK4 upon TLR stimulation is mediated by the myeloid differentiation primary response 88 (MYD88) adaptor protein. Around 3% of chronic lymphocytic leukemia (CLL) patients have activating mutations of MYD88, a driver mutation in this disease. Here, we studied the effects of TLR activation and the pharmacological inhibition of IRAK4 with ND2158, an IRAK4 competitive inhibitor, as a therapeutic approach in CLL. Our in vitro studies demonstrated that ND2158 preferentially killed CLL cells in a dose-dependent manner. We further observed a decrease in NF-κB and STAT3 signaling, cytokine secretion, proliferation and migration of primary CLL cells from MYD88-mutated and -unmutated cases. In the Eµ-TCL1 adoptive transfer mouse model of CLL, ND2158 delayed tumor progression and modulated the activity of myeloid and T cells. Our findings show the importance of TLR signaling in CLL development and suggest IRAK4 as a therapeutic target for this disease.

Promoter methylation and expression of SOCS3 affect the clinical outcome of pediatric acute lymphoblastic leukemia by JAK/STAT pathway

Suppressor of cytokine signaling 3 (SOCS3) has been characterized as one of the most crucial negative regulator in the JAK2/STAT3 signaling pathway. However, there are few studies on the relationship between SOCS3 and pediatric acute lymphoblastic leukemia (ALL). This study analyzes the influence of SOCS3 expression on the risk and the progression of pediatric ALL and the underlying mechanism. The levels of SOCS3, p-JAK2, p-STAT3, SOCS3 methylation, CD4+CD25+CD127lowTreg were detected by PCR, laser confocal microscopy, western blot, bisulfite sequencing and flow cytometry at different progression of ALL. We found that the SOCS3 expression level at initial diagnosis (DG) of ALL patients was significantly lower than that of healthy controls (HC), while the expression of SOCS3 methylation was opposite. The expression of SOCS3 and SOCS3 methylation were returned to normal in the complete remission (CR) stage, and there were no difference between resistance, relapse and initial diagnosis. The expression of SOCS3 decreased and weakened the inhibition of pSTAT3 expression in DG, resistance and relapse groups. The levels of Treg cells in ALL children were significantly higher than those in the HC children. There was a positive correlation between the expression level of STAT3 and the expression level of Treg cells in children with ALL, while that was negatively correlated with the expression levels of Treg cells. Compared with high-level of SOCS3, the low-level of SOCS3 patients had more high risk factors, as higher WBC counts, LDH level and much more poor prognostic genes. SOCS3 methylation leads to low-expression of SOCS3, which can lead to continuous activation of JAK/STAT3 and increased expression of Treg cells, which in turn affects the anti-tumor immunological effect of the body. Taken together, our data show that monitoring the level of SOCS3 can contribute to the understanding of the state of illness and evaluate the risk of progression of ALL.

Increased autocrine interleukin-6 production is significantly associated with worse clinical outcome in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) remains incurable with current standard therapy. We have previously reported that an increased expression of interleukin‐6 (IL‐6) receptor CD126 leads to resistance of CLL cells to chemotherapy and worse prognosis for patients with CLL. In this study, we determine whether autocrine IL‐6 production by CLL B cells is associated with poor clinical outcome and explore IL‐6‐mediated survival mechanism in primary CLL cells. Our results demonstrate that higher levels of autocrine IL‐6 are significantly associated with shorter absolute lymphocyte doubling time, patients received treatment, without complete remission, advanced Binet stages, 17p/11q deletion, and shorter time to first time treatment and progression‐free survival. IL‐6 activated both STAT3 and nuclear factor kappa B (NF‐κB) in primary CLL cells. Blocking IL‐6 receptor and JAK2 inhibited IL‐6‐mediated activation of STAT3 and NF‐κB. Our study demonstrates that an increased autocrine IL‐6 production by CLL B‐cells are associated with worse clinical outcome for patients with CLL. IL‐6 promotes CLL cell survival by activating both STAT3 and NF‐κB through diverse signaling cascades. Neutralizing IL‐6 or blocking IL‐6 receptor might contribute overcoming the resistance of CLL cells to chemotherapy. We propose that the measurement of autocrine IL‐6 could be a useful approach to predict clinical outcome.

Inhibition of the Raf-1 kinase inhibitory protein (RKIP) by locostatin induces cell death and reduces the CXCR4-mediated migration of chronic lymphocytic leukemia cells

The Raf-1 kinase inhibitory protein (RKIP) is an important regulatory element in multiple signaling pathways, including MAPK-ERK1/2. We investigated whether targeted disruption of RKIP is a therapeutic option for chronic lymphocytic leukemia (CLL). The RKIP inhibitor locostatin-induced apoptosis of CLL cells, irrespective of poor prognostic indications or treatment history. Locostatin down-regulated MAPK-ERK1/2 and AKT phosphorylation, decreased expression of the chemokine receptor CXCR4 (p = .04) and reduced the migratory capacity of CLL cells toward stroma-derived factor 1α (SDF-1α, p = .02). Immuno-blotting and immuno-precipitation showed that RKIP is constitutively phosphorylated and highly expressed in CLL cells and that the actions of locostatin may be mediated by binding of G-protein receptor kinase-2 (GRK2) to MEK1 and AKT. Collectively, our data suggest that inhibition of RKIP may be effective against CLL, reducing the survival and migratory capacity of the leukemic cells through down-regulation of MAPK-ERK1/2 and AKT-mediated signaling.

Ellagic acid induces HeLa cell apoptosis via regulating signal transducer and activator of transcription 3 signaling

Ellagic acid has been reported to possess various activities, including anti-inflammatory, anti-oxidative, antiviral and anticancer abilities. However, the effect and underlying molecular mechanism of ellagic acid on cervical carcinoma remain unclear. Therefore, the present study aimed to investigate the effects of ellagic acid on human cervical carcinoma cells and the molecular mechanism involved. The present study assessed the survival of HeLa cells cultured in vitro using an MTT assay. Apoptosis rate and cell cycle of HaLa cells were measured using an Annexin V-Fluorescein isothiocyanate/propidium iodide Apoptosis Detection and Cell Cycle Analysis kits, respectively, following treatment with varying concentrations of ellagic acid. Further effects of ellagic acid on HeLa cells was assessed using flow cytometry and western blotting. Ellagic acid treatment significantly inhibited cell proliferation of the human cervical carcinoma HeLa, SiHa and C33A cells. In HeLa cells, it was observed that ellagic acid arrested the cell cycle at G1 phase, induced cell apoptosis, suppressed the phosphorylation of Janus kinase 2 and signal transducer and activator of transcription 3 (STAT3), as well as modulated the expression of associated proteins. Collectively, the results of the present study provide evidence that ellagic acid inhibits cervical carcinoma cell proliferation, and induces apoptosis and cell cycle arrest at G1 phase possibly via the regulation of STAT3 signaling.

Microenvironment-induced PIM kinases promote CXCR4-triggered mTOR pathway required for chronic lymphocytic leukaemia cell migration

Lymph node microenvironment provides chronic lymphocytic leukaemia (CLL) cells with signals promoting their survival and granting resistance to chemotherapeutics. CLL cells overexpress PIM kinases, which regulate apoptosis, cell cycle and migration. We demonstrate that BCR crosslinking, CD40 stimulation, and coculture with stromal cells increases PIMs expression in CLL cells, indicating microenvironment‐dependent PIMs regulation. PIM1 and PIM2 expression at diagnosis was higher in patients with advanced disease (Binet C vs. Binet A/B) and in those, who progressed after first‐line treatment. In primary CLL cells, inhibition of PIM kinases with a pan‐PIM inhibitor, SEL24‐B489, decreased PIM‐specific substrate phosphorylation and induced dose‐dependent apoptosis in leukaemic, but not in normal B cells. Cytotoxicity of SEL24‐B489 was similar in TP53‐mutant and TP53 wild‐type cells. Finally, inhibition of PIM kinases decreased CXCR4‐mediated cell chemotaxis in two related mechanisms‐by decreasing CXCR4 phosphorylation and surface expression, and by limiting CXCR4‐triggered mTOR pathway activity. Importantly, PIM and mTOR inhibitors similarly impaired migration, indicating that CXCL12‐triggered mTOR is required for CLL cell chemotaxis. Given the microenvironment‐modulated PIM expression, their pro‐survival function and a role of PIMs in CXCR4‐induced migration, inhibition of these kinases might override microenvironmental protection and be an attractive therapeutic strategy in this disease.

CXCR1/2 pathways in paclitaxel-induced neuropathic pain

Chemotherapy-induced peripheral neuropathy (CIPN) is a type of neuropathic pain that represents a frequent and serious consequence of chemotherapy agents. Over the last years, significant progress has been achieved in elucidating the underlying pathogenesis of CIPN. The interference of taxanes with microtubule has been proposed as a mechanism that leads to altered axonal transport and to permanent neurological damages. The inflammatory process activated by chemotherapeutic agents has been considered as a potential trigger of nociceptive process in CIPN.

In this study we investigated the effect of reparixin, an inhibitor of CXCR1/CXCR2, in suppressing the development of paclitaxel-induced nociception in rats. Moreover, reparixin activity in reversing the neurotoxic effects induced by paclitaxel or GRO/KC in F11 cells was also analyzed.

Reparixin administered by continuous infusion ameliorated paclitaxel-induced mechanical and cold allodynia in rats. In F11 cells, reparixin was able to inhibit the increase of acetyladed α-tubulin induced both by paclitaxel and GRO/KC. The subsequent experiments were performed in order to dissect the signal transduction pathways under GRO/KC control, eventually modulated by paclitaxel and/or reparixin. To this aim we found that reparixin significantly counteracted p-FAK, p-JAK2/p-STAT3, and PI3K-p-cortactin activation induced either by paclitaxel or GRO/KC.

Overall the present results have identified IL-8/CXCR1/2 pathway as a mechanism involved in paclitaxel-induced peripheral neuropathy. In particular, the obtained data suggest that the inhibition of CXCR1/2 combined with standard taxane therapy, in addition to potentiating the taxane anti-tumor activity can reduce chemotherapy-induced neurotoxicity, thus giving some insight for the development of novel treatments.

TRIM8: Making the Right Decision between the Oncogene and Tumour Suppressor Role

The TRIM8/GERP protein is a member of the TRIM family defined by the presence of a common domain structure composed of a tripartite motif including a RING-finger, one or two B-box domains, and a coiled-coil motif. The TRIM8 gene maps on chromosome 10 within a region frequently found deleted and rearranged in tumours and transcribes a 3.0-kB mRNA. Its expression is mostly ubiquitously in murine and human tissues, and in epithelial and lymphoid cells, it can be induced by IFNγ. The protein spans 551 aa and is highly conserved during evolution. TRIM8 plays divergent roles in many biological processes, including important functions in inflammation and cancer through regulating various signalling pathways. In regulating cell growth, TRIM8 exerts either a tumour suppressor action, playing a prominent role in regulating p53 tumour suppressor activity, or an oncogene function, through the positive regulation of the NF-κB pathway. The molecular mechanisms underlying this dual role in human cancer will be discussed in depth in this review, and it will highlight the challenge and importance of developing novel therapeutic strategies specifically aimed at blocking the pro-oncogenic arm of the TRIM8 signalling pathway without affecting its tumour suppressive effects.