Expression Of Bcl-2 Family Proteins Research Articles

S6K1 inhibition enhances the apoptotic cell death of breast cancer cells in response to Bcl-2/Bcl-xL inhibition by the downregulation of survivin.

Breast cancer cells possess a deregulated apoptotic pathway with increased expression levels of anti-apoptotic B-cell lymphoma-2 (Bcl-2) family proteins and ribosomal S6 kinase 1 (S6K1) protein activity. Therefore, combined interference of anti-apoptotic Bcl-2 family and S6K1 protein expression may be a reasonable therapeutic strategy for the treatment of patients with breast cancer. In the present study, it was identified that the administration of a combination of ABT263 [navitoclax; a Bcl-2/Bcl-extra large (Bcl-xL) inhibitor] and PF4708671 (an S6K1 inhibitor) markedly increased apoptotic cell death in the BT474 breast cancer cells compared with the administration of either agent alone. Furthermore, the downregulation of Bcl-2/Bcl-xL and S6K1 with small interfering RNA induced a significant increase in cell death compared with RNA interference of either agent alone. Notably, combination treatment with ABT263 and PF4708671 decreased the expression level of survivin protein, with this ectopic expression of survivin attenuating cell death. Thus, the present study determined that the combined inhibition of Bcl-2/Bcl-xL and S6K1 may be a good strategy for treating patients with breast cancer.

Thalidomide can promote erythropoiesis by induction of STAT5 and repression of external pathway of apoptosis resulting in increased expression of GATA-1 transcription factor.

Thalidomide was shown to stimulate erythropoiesis and increase hemoglobin level in multiple myeloma patients, but way of such activity remains unclear. The aim of the study was to investigate the mechanisms of thalidomide stimulating effect on erythroid differentiation. Hematopoietic stem cells were isolated from bone marrow aspirates taken from myeloma patients and cultured with or without thalidomide. Then the generation of erythroid cells and the expression of STAT5, GATA-1, GATA-2, selected caspases and Bcl-2 family proteins in erythroid cells were assessed using flow cytometry and real-time PCR. The generation of erythroblasts was higher in thalidomide than in control cultures (63.9% vs. 55.8%, p < 0.001). The expression of caspase 3 (cytometry 947.3 vs. 1021.0, p = 0.025; PCR 12.9 vs. 16.3, p = 0.025) and caspase 8 (cytometry 1050.8 vs. 1168.5, p = 0.033; PCR 16.2 vs. 17.8, p = 0.004) was significantly lower in thalidomide than in control cultures. The expression of STAT5 (cytometry 331.5 vs. 276.1, p = 0.015; PCR 24.3 vs. 21.1, p = 0.003) and GATA-1 (cytometry 259.7 vs. 232.0, p = 0.027; PCR 18.9 vs. 16.5, p = 0.003) was higher in thalidomide than in control cultures. Our results suggest that thalidomide enhances expression of STAT5 in response of erythroid cells to erythropoietin and as a result of caspase 3 suppression. Moreover it may exert inhibitory effect on an external pathway of caspases activation with consequent decreased degradation of GATA-1 transcription factor by downstream caspases.

Anticancer activity studies of a ruthenium(II) polypyridyl complex against human hepatocellular (BEL-7402) cells

A Ru(II) polypyridyl complex [Ru(bpy)2(HMSPIP)](ClO4)2 (1) (bpy=2,2′-bipyridine, HMSPIP=2-(4-methylsulfonyl)phenyl-1H-imidazo[4,5-f][1,10] phenanthroline) was synthesized. The IC50 value of the complex against human hepatocellular cell BEL-7402 is 21.6±2.7μM. The complex shows no cytotoxic activity toward human lung adenocarcinoma cell A549, human osteosarcoma cell MG-63 and human breast cancer cell SK-BR-3 cells. It is easily for complex 1 to be taken up by BEL-7402 cells. The complex can enhance the reactive oxygen species (ROS) levels and induce the decrease in the mitochondrial membrane potential. The complex inhibits the cell growth in BEL-7402 cells at G2/M phase. Complex 1 can regulate the expression of Bcl-2 family proteins. The results show that the complex induces apoptosis of BEL-7402 cells through a ROS-mediated mitochondrial dysfunction pathway.

Paeoniflorin inhibits nucleus pulposus cell apoptosis by regulating the expression of Bcl-2 family proteins and caspase-9 in a rabbit model of intervertebral disc degeneration.

Apoptosis plays a key role in the pathogenesis of internal disc disruption (IDD); therefore, the inhibition of apoptosis may offer a novel approach for treating IDD diseases. The aim of the present study was to investigate the effects and the underlying mechanisms of paeoniflorin through the detection of relevant indicators in a rabbit model of IDD. In total, 144 rabbits were used in the study and divided into four groups (n=36 per group). Rabbits successfully modeled with IDD received an intragastric injection of 120 mg/kg·day paeoniflorin (high-dose group), 30 mg/kg·day paeoniflorin (low-dose group) or saline (model saline group), while rabbits without IDD were used as a normal control group. The apoptosis rate of disc nucleus pulposus cells was detected using flow cytometry. In addition, the expression levels of Bcl-2, Bax and caspase-9 in the disc tissues were detected using immunohistochemistry and western blot analysis prior to and following the treatment. The results indicated that the expression levels of Bax in the low- and high-dose paeoniflorin groups were significantly reduced, while the Bcl-2 expression levels were significantly increased when compared with the model saline group (P<0.01). In addition, the expression levels of cleaved caspase-3 and cleaved caspase-9 were reduced in the low- and high-dose paeoniflorin groups, as compared with the model saline group (P<0.05). Furthermore, the average apoptotic index of the high- and low-dose paeoniflorin groups was decreased when compared with the model saline group (P<0.05). In conclusion, paeoniflorin was demonstrated to inhibit the apoptosis of nucleus pulposus cells and the activation of caspase-3 and caspase-9 through the regulation of Bcl-2 family protein expression. These results provide an experimental basis for the future treatment of IDD with paeoniflorin.

Mcl-1 is vital for neutrophil survival.

Upon entry to the systemic circulation, neutrophils exhibit a short mean time to cell death. The viability of most cell types in a steady state is preserved by the interplay of the Bcl-2 family of proteins, wherein the anti-apoptotic members inhibit the action of their pro-apoptotic counterparts. Neutrophils, however, display absent or severely reduced expression of several anti-apoptotic Bcl-2 family proteins. Hence, they rely on the expression of Mcl-1, an anti-apoptotic member of the Bcl-2 family, for survival. This protein is uniquely short-lived relative to related proteins and its loss likely precipitates the induction of apoptosis in neutrophils. This review describes the role of Mcl-1 in the neutrophil in the context of apoptosis and highlights the proteins' importance to the cell. We also address neutrophil apoptosis in the broader context of the cells' response to pathogens, focussing particularly on the strategies used by pathogens to manipulate the apoptotic pathway to their own ends.

Low expression of pro-apoptotic Bcl-2 family proteins sets the apoptotic threshold in Waldenström macroglobulinemia.

Waldenström Macroglobulinemia (WM) is a proliferative disorder of IgM secreting, lymphoplasmacytoid cells that inhabit the lymph nodes and bone marrow. The disease carries a high prevalence of activating mutations in MyD88 (91%) and CXCR4 (28%). Because signaling through these pathways leads to Bcl-xL induction, we examined Bcl-2 family expression in WM patients and cell lines. Unlike other B-lymphocyte-derived malignancies, which become dependent on expression of anti-apoptotic proteins to counter expression of pro-apoptotic proteins, WM samples expressed both pro- and anti-apoptotic Bcl-2 proteins at low levels similar to their normal B-cell and plasma cell counterparts. Three WM cell lines expressed pro-apoptotic Bcl-2 family members Bim or Bax and Bak at low levels which determined their sensitivity to inducers of intrinsic apoptosis. In two cell lines, miR-155 upregulation, which is common in WM, was responsible for inhibition of FOXO3a and Bim expression. Both antagonizing miR-155 to induce Bim and proteasome inhibition increased the sensitivity to ABT-737 in these lines indicating a lowering of the apoptotic threshold. In this manner, treatments that increase pro-apoptotic protein expression increase the efficacy of agents treated in combination in addition to direct killing.

Sesamin suppresses STZ induced INS-1 cell apoptosis through inhibition of NF-κB activation and regulation of Bcl-2 family protein expression

Diverse risk factors for diabetes can induce oxidative stress, leading to pancreatic beta cell damage and insulin secretion dysfunction. In the present study, we evaluated the effect of sesamin on streptozotocin (STZ) induced apoptosis in INS-1 cells and the possible mechanisms implicated. After preincubation with indicated concentrations of sesamin (0.1, 1.0 and 10.0μmol/l) for 24h, INS-1 cells were exposed to STZ (3mmol/l) for 12h. Sesamin effectively improved STZ induced cell damage as determined by MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide] assay and insulin secretion capacity, and suppressed STZ induced cell apoptosis as evaluated by flow cytometry using annexin V and propidium iodide double staining. Western blot analysis demonstrated that sesamin markedly suppressed STZ induced nuclear factor kappa B (NF-κB) activation, with Bax protein down-regulated and Bcl-2 protein up-regulated significantly. Preincubation with sesamin resulted in an evident enhancement of total antioxidant capacity in INS-1 cells, accompanied by a significant reduction of intracellular reactive oxygen species and malondialdehyde, an end product of lipid peroxidation. Taken together, these findings suggested that sesamin was capable of suppressing STZ induced INS-1 cell apoptosis, which might be ascribed, at least partly, to the inhibition of NF-κB activation and subsequent regulation of Bcl-2 family protein expression. This study would provide a potential target for treatment of diabetes with sesamin as well as other antioxidants.

Clic4, a novel protein that sensitizes β-cells to apoptosis.

ObjectivesChloride intracellular channel protein 4 (Clic4) is a ubiquitously expressed protein involved in multiple cellular processes including cell-cycle control, cell differentiation, and apoptosis. Here, we investigated the role of Clic4 in pancreatic β-cell apoptosis.MethodsWe used βTC-tet cells and islets from β-cell specific Clic4 knockout mice (βClic4KO) and assessed cytokine-induced apoptosis, Bcl2 family protein expression and stability, and identified Clic4-interacting proteins by co-immunoprecipitation and mass spectrometry analysis.ResultsWe show that cytokines increased Clic4 expression in βTC-tet cells and in mouse islets and siRNA-mediated silencing of Clic4 expression in βTC-tet cells or its genetic inactivation in islets β-cells, reduced cytokine-induced apoptosis. This was associated with increased expression of Bcl-2 and increased expression and phosphorylation of Bad. Measurement of Bcl-2 and Bad half-lives in βTC-tet cells showed that Clic4 silencing increased the stability of these proteins. In primary islets β-cells, absence of Clic4 expression increased Bcl-2 and Bcl-xL expression as well as expression and phosphorylation of Bad. Mass-spectrometry analysis of proteins co-immunoprecipitated with Clic4 from βTC-tet cells showed no association of Clic4 with Bcl-2 family proteins. However, Clic4 co-purified with proteins from the proteasome suggesting a possible role for Clic4 in regulating protein degradation.ConclusionsCollectively, our data show that Clic4 is a cytokine-induced gene that sensitizes β-cells to apoptosis by reducing the steady state levels of Bcl-2, Bad and phosphorylated Bad.

In Vitro and In Vivo Antitumor Effects of n-Butanol Extracts of Pterocephalus hookeri on Hep3B Cancer Cell.

Pterocephalus hookeri is a widely applied Tibetan medicinal prescription for treatment of diseases such as flu, rheumatoid arthritis, and enteritis in China. It has been reported that Pterocephalus hookeri has anti-inflammatory and analgesic actions. However, the antitumor activity of Pterocephalus hookeri remains unknown. In the present study, we demonstrate that n-butanol extracts of Pterocephalus hookeri (YSC-ZDC) has a strong antitumor activity against hepatoma carcinoma cell in vitro and in vivo. YSC-ZDC inhibited proliferation of all cancer cell lines and significantly inhibited Hep3B cells proliferation in a dose- and time-dependant manner. Transmission electron microscopy, hoechst 33258 staining, and flow cytometry analysis revealed that YSC-ZDC induced apoptosis in Hep3B cells. YSC-ZDC treatment dramatically inhibited PDK1 and Akt phosphorylation in Hep3B cells. Moreover, YSC-ZDC increased Bax expression and inhibited Bcl-2 expression. In addition, YSC-ZDC inhibited growth hepatoma xenografts in vivo with no effect on body weight and spleen index. Consistent with results in vitro, YSC-ZDC increased Bax expression and inhibited Bcl-2 expression in tumor tissue. Taken together, this study shows YSC-ZDC with an antitumor activity both in vitro and in vivo. Its mechanism underlying is related to blocking of the Akt pathway and regulation of Bcl-2 family proteins expression.

The small-molecule compound BM-1197 inhibits the antiapoptotic regulators Bcl-2/Bcl-xL and triggers apoptotic cell death in human colorectal cancer cells.

Small molecule BH3 mimetics comprise a promising new chemotherapeutic strategy for treating relapsed or chemoresistant cancer. In this study, we investigated the cellular mechanism of action by which BM-1197, a Bcl-xL/Bcl-2 dual inhibitor, triggers apoptosis in a panel of colorectal cancer (CRC) lines. Using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, we determined that BM-1197 inhibited CRC cell growth in a concentration- and time-dependent manner. The 50 % inhibitory concentration (IC50) values for the most sensitive cell lines, SW620 and SW480, ranged from 0.07 to 1.10 μM in response to a 72-h treatment. In CRC cells, BM-1197 induced apoptotic death without affecting the expression of Bcl-2 family proteins. However, BM-1197 effectively triggered a conformational change in Bax, releasing Bim from Bcl-xL by disrupting the interaction between Bcl-xL and Bak/Bax. Compared with the control group, BM-1197 treatment significantly increased the fraction of SW480 cells in the sub-G1 phase, the apoptosis rate, and cellular internucleosomal DNA fragmentation. The proapoptotic activity was associated with cytochrome c release, caspase-3 activation, and PARP-1 cleavage. Collectively, BM-1197 effectively suppressed the growth of the human CRC cell line SW480 by inducing mitochondria-dependent apoptotic cell death. These data have specific implications for the in vivo analysis and clinical evaluation of BM-1197 in CRC.

A novel therapeutic combination sequentially targeting aurora B and Bcl-xL in hepatocellular carcinoma.

Effective therapeutic combinations targeting the oncogenic pathway still are unknown in human hepatocellular carcinoma (HCC). The authors previously identified aberrant expression of aurora B kinase as the independent predictor for the lethal recurrence of HCC, showing that AZD1152 induced in vitro and in vivo apoptosis with polyploidy in human HCC cells. In this preclinical study, the combined effects of molecular-targeted therapies were evaluated based on the cellular response of aurora B inhibition. This study analyzed the expression of Bcl-2 family proteins in polyploidization induced by AZD1152 and the in vitro synergistic effects of AZD1152 with control of the Bcl-2 family pathway in human HCC cells. The in vivo effects of the combination therapy targeting the specific molecules were evaluated using subcutaneous tumor xenograft models. The findings showed that Bcl-xL was specifically overexpressed in AZD1152-induced polyploid HCC cells. The combination of AZD1152 followed by Bcl-xL/2 inhibitor ABT263 induced synergistically cellular apoptosis (p < 0.001) and growth inhibition (p < 0.0001). Interestingly, the reverse sequential administration of AZD1152 combined with pretreatment of ABT263 was less effective than the original one. In vivo studies using tumor xenografts of human HCC cells showed that combination therapy of ABT263 after AZD1152 pretreatment induced significant intratumoral apoptosis (p < 0.05) and remarkable anti-tumor effects (p < 0.05) without a severe adverse effect compared with the monotherapy. Based on Bcl-xL overexpression in polyploidy induced by aurora B inhibition, the rationale for therapeutic combinations targeting aurora B and Bcl-xL was demonstrated in the authors' preclinical studies, leading to a promising novel approach for the mechanism-based treatment of human HCC.

Collateral sensitivity to cold stress and differential BCL-2 family expression in new daunomycin-resistant lymphoblastoid cell lines

The acquisition of a multidrug-resistant (MDR) phenotype by tumor cells is one of the main causes of chemotherapy failure in cancer, and, usually, is due to the increased expression of P-glycoprotein (MDR-1, P-gp, ABCB1), a pump that expels chemotherapeutics from the cell and/or regulates apoptosis. Thus, it is fundamental to find drugs or stress stimuli with a capacity to induce apoptosis in such cells and to identify the mechanisms involved. We address this matter in human cells and establish new daunomycin (DNM)-resistant cell lines (IM-9R) by exposing the parental lymphoblastic cells (IM-9) to increasing doses of the anti-neoplastic drug, daunomycin. The resistance level of IM-9R cell lines, MDR-1 expression and functionality, collateral sensitivity and Bcl-2 and caspases protein expression are analyzed. As a result, we show for the first time that, unlike the parental cells, human lymphoblastic resistant cells exhibit collateral sensitivity to cold stress, confirming that this phenomenon is not exclusive to murine leukemic cells, but a broader one associated with the acquisition of drug resistance. Furthermore, the new resistant cell lines undergo a significant increase in active caspase-3 and -9 levels and drastic changes in Bcl-2 family protein expression during the process of MDR phenotype acquisition.

Effects of selenium on lead-induced alterations in Aβ production and Bcl-2 family proteins

Previous studies in humans and animals have suggested that lead (Pb) may increase the expression of amyloid precursor protein (APP) and accumulation of amyloid β protein (Aβ). Our previous studies have revealed that selenium (Se) can partially improve memory deficits induced by Pb exposure. In this study we sought to investigate the effect of Pb and Se on the endogenous expression of APP, Aβ40 and Bcl-2 family proteins. In vitro, the protein levels of APP and Aβ significantly decreased in SH-SY5Y and PC12 cells co-incubated with Pb-acetate and selenomethionine (SeMet) for 48h, compared with cells treated with Pb-acetate alone. Furthermore, these reductions induced by Se appeared to be concentration-dependent. In Wistar rats, we observed that the mRNA and protein levels of APP, the protein level of Bax, and the ratio of Bax/Bcl-2 protein significantly increased after Pb treatment at embryonic stage and in neonates. These increases were significantly reversed by the treatment of Se. Taken together, our results suggest that Se can attenuate the alterations in APP expression and Aβ production as well as Bcl-2 family proteins induced by lead exposure in cells and in animals.

Desialylation Induces Apoptosis and Phagocytosis of Platelets in Patients with Prolonged Isolated Thrombocytopenia after Allogeneic Hematopoietic Stem Cell Transplantation

Introduction:Prolonged isolated thrombocytopenia (PIT) represents a significant complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT), and is associated with an adverse patient prognosis and higher transplant-related mortality owing to a higher risk of infection events, severe (grades 3 to 4) acute graft-versus-host disease (GVHD) and chronic GVHD. PIT is defined as a peripheral platelet count less than 100×109/L without sustained anemia or leukopenia for more than 3 months after allo-HSCT (Zhang X, et al. Biol Blood Marrow Transplant, 2011). However, the underlying mechanisms remain unclear. Different kinds of functional glycoproteins are expressed on the platelet surface, with sialic acid residues at the end of their glycan. Desialylation of platelet glycoproteins has been found to be associated with accelerated platelet clearance in refrigerated platelets (Gerard Jansen AJ, et al. Blood 2012). Platelet-specific glycoprotein GPIbα,the functional subunit of the von Willebrand factor receptor, was the majorly desialylated glycoprotein; NEU1, one of the four human sialidases, was the enzyme that catalyzed GPIbα desialylation. However, few studies have focused on this mechanism in patients suffering PIT after allo-HSCT. In this study, we hypothesized that desialylation on platelet surfaces is associated with PIT after allo-HSCT. The mechanisms participating in this process may include GPIbα clustering, platelet apoptosis and phagocytosis by macrophages.Patients and methods:Blood samples were collected 90 days after allo-HSCT from 70 patients with PIT. Samples from post-transplantation patients who have normal platelet counts were taken as controls. Sialylation and desialylation were measured by detecting specific lectins via flow cytometry. Human sialidase expression was determined by immunofluorescence, flow cytometry and reverse transcription PCR. Platelet apoptosis markers were measured by flow cytometry, and macrophages stimulated from THP-1 cells were used in the phagocytosis assay.Results:We tested sialic acid residues and the desialylation markers, including β-galactose and β-N-Acetyl glucosamine, on the platelet surface, and found that platelets from PIT patients had significantly higher desialylation levels. Serum sialic acid levels were measured, and the results showed higher levels in PIT patients. Further, NEU1 was found to be over-expressed on the surface of platelets from PIT patients, and was found to be the enzyme that catalyzed the platelet surface desialylation. To further reveal the mechanism that lead to PIT, we proved that GPIbα was the desialylated glycoprotein on platelets from PIT patients. We found that GPIbα desialylation and clustering in PIT patients induced changes in the expression of Bcl-2 family protein, as a 2-fold increase in active Bax expression and a similar decrease in Bcl-XL expression were observed. Depolarization of the inner mitochondria membrane was augmented in desialylated platelets from PIT patients, indicating increased platelet apoptosis. Moreover, macrophages stimulated from the THP-1 cell line preferred to phagocytose desialylated platelets from PIT patients in vitro; this process could be blocked by the sialidase inhibitor, DANA. In the in vitrostudy, we found that dexamethasone led to a 32% decrease in phagocytosis, whereas oseltamivir, an antiviral medicine that can block sialidase from influenza virus, could also partially function on human sialidase and protect 43% of platelets from phagocytosis.In conclusion, our results demonstrate that desialylation played a role in the mechanism of prolonged isolated thrombocytopenia after allo-HSCT, most likely through platelet apoptosis induction and increased phagocytosis by macrophages in the peripheral circulation. Dexamethasone and oseltamivir could decrease platelet apoptosis and inhibit platelet phagocytosis in vitro, implying a novel potential method for treating PIT after allo-HSCT. DisclosuresNo relevant conflicts of interest to declare.

Inhibition of Nuclear Factor Kappa B (NFkB)/Interferon Regulatory Factor 4 (IRF4) Signaling Pathway in Activated B-Cell (ABC) Diffuse Large B-Cell Lymphoma (DLBCL) By Combining MLN4924, a Novel NEDD8 Activating Enzyme Inhibitor (NAE) and Ibrutinib

Abstract Identification of critical signaling pathways required for the development, maintenance and progression of specific subtypes of DLBCL is essential in order to develop novel therapeutic agents, especially for patients with relapsed/refractory disease or those not eligible for high-dose chemotherapy and autologous stem cell support (HDC-ASCT). Gene expression profiling (GEP) studies have identified three distinct subtypes of DLBCL- ABC-DLBCL, germinal center B-cell (GCB) DLBCL and primary mediastinal B-cell lymphoma (PMBL). Pre-clinical and clinical studies suggest that ABC-DLBCL is driven by an abnormally high NFκB activity that deregulates expression of Bcl-2 family proteins, and is associated with resistance to chemotherapy agents resulting in inferior clinical outcomes when compared to GCB-DLBCL or PMBL. In ABC-DLBCL, activation and maintenance of NFκB is mediated by the B-cell receptor (BCR) signaling pathway, the ubiquitin-proteasome system (UPS), oncogenic CARD11 or MYD88 mutations, and/or the effect of IRF4/SPIB on CARD11 or MYD88. Optimal NFκB targeting is an attractive therapeutic strategy in ABC-DLBCL and ongoing clinical trials are incorporating specific inhibitors (bortezomib, lenalidomide, or ibrutinib) in combination with chemo-immunotherapy in the front-line setting. On the other hand, multi-step targeting of the NFκB signaling pathway in ABC-DLBCL using investigational and currently available small molecule inhibitors could result in novel, active, and potentially less toxic regimens for ABC-DLBCL patients. To this end we studied the biological activity of MLN4924, a NAE inhibitor that selectively blocks the UPS up-stream by preventing activation of a subset of ubiquitin ligases known as cullin-RING ligases in combination with ibrutinib in lymphoma pre-clinical models. A panel of rituximab sensitive or resistant lymphoma cell lines representing ABC- and GCB-DLBCL were exposed to MLN4924. Changes in cell viability, cell cycle/NFκB activity, and expression of key regulatory proteins of the cell cycle, Bcl-2 family members, and the UPS were evaluated using the cell titer glo assay, flow cytometry and western blotting respectively. Subsequently, ABC- or GCB-DLBCL cell lines and tumor cells isolated from previously untreated or relapsed/refractory B-cell lymphoma were exposed to MLN4924 in combination with various chemotherapy agents or other available NFkB inhibitors (i.e. ibrutinib) for 24 or 48 hrs. Changes in viability were determined and coefficient of synergy was calculated using the CalcuSyn software. MLN4924 induced cell death in ABC-DLBCL cell lines and to a lesser degree in GCB-DLBCL cell lines. Anti-tumor activity plateau was seen after 48 hrs of drug exposure. In MLN4924 sensitive cells we consistently observed cell cycle arrest in G1 phase, down-regulation of Bcl-XL and PARP cleavage. MLN4924 exposure in vitro resulted in a decrease in Bcl-XL mRNA as determined by quantitative polymerase chain reaction (qPCR),due to the inhibition of NFkB activity as demonstrated in MLN4924-exposed cells by p65 co-localization studies using the imagestream technology. MLN4924 enhanced activity of cytarabine, cisplatin, doxorubicin and etoposide in ABC-, but not in the GCB-DLBCL cell lines. MLN4924 also exhibited synergistic effects when combined with ibrutinib in ABC-DLBCL cell lines at the doses tested. Our data suggests that multi-step targeting of NFκB signaling pathway in ABC-DLBCL is a viable therapeutic strategy and supports further in vivo pre-clinical studies and clinical studies in relapsed/refractory or HDC-ASCT ineligible ABC-DLBCL patients. (Research, in part, supported by a NIH grant R01 CA136907-01A1 awarded to Roswell Park Cancer Institute and The Eugene and Connie Corasanti Lymphoma Research Fund) Disclosures No relevant conflicts of interest to declare.

Oxymatrine Induces Apoptosis in Human Myeloma Cells By Cell Cycle Arrest and Activation of Caspase-Dependent Apoptosis

Background : Multiple myeloma (MM) is a B cell malignant hematologic cancer. Despite the introduction of new drugs and improvement of chemotherapy, MM is still an incurable disease. Oxymatrine (OMT), the active ingredients of traditional Chinese herbal medicine sophora, has been reported to have antitumor activity. This study was to estimate the therapeutic efficacy of OMT in MM.Methods: The growth inhibition of myeloma cell lines (RPMI8226, U266, ARP-1) or primary cells by OMT was assessed by MTT assay. Apoptosis of MM cells was examined by annexin V-FITC using flow cytometry analysis. DNA content was analyzed by flow cytometry. RT-PCR and western-blot analysis were used to assess the expression of Bcl-2 family proteins and the IAP family proteins. Western blotting was also used to elucidate the signaling pathway that may mediate OMT-induced apoptosis of MM cells.Results: OMT treatment resulted in cell growth inhibition and apoptosis in primary MM cells and all tested MM cell lines in a dose-dependent manner (P <0.05). To elucidate OMT -induced MM cell apoptosis, MM cell lines were treated with or without OMT for 24h and assessed for caspase activation and signaling pathway by Western blotting. The results showed the cleavage of PARP, caspase-3, and caspase-9, and p-AKT were down-regulated after OMT treatment. The mRNA expression of survivin and HIAP by RT-PCR was down-regulated. OMT treatment at 5mM for 48h resulted in increased G-phase cells and decreased S-phase cells in MM cell lines (P <0.05). Cell cycle repressor P21 protein was up-regulated while CDK4, CDK6 and CyclinD1 expression was down-regulated. Our finding also showed a synergistic anti-MM activity of OMT and dexamethasone or adriamycin at a low does (CI<1). In addition, LC3-II expression was significantly increased both in RPMI8226 and U266 cells after treatment with OMT. However, treatment with different doses of OMT and 5 mM autophagy inhibitor 3-MA, significant increased cell apoptosis (P <0.05).Conclusion: Our findings demonstrate the anti-MM activity of OMT and indicate that OMT alone or together with other MM chemotherapeutics may be a prospective treatment for MM. DisclosuresNo relevant conflicts of interest to declare.

Polysaccharides produced by Enterobacter cloacae induce apoptosis in cervical cancer cells

The effects and possible mechanism of polysaccharides produced by Enterobacter cloacae (EPS) on cervical cancer cells (Hela and SiHa) were investigated in vitro in the current study. The results showed that supplementation of EPS inhibited the proliferation of HeLa and SiHa cells in a concentration- and time-dependent manner. In addition, the EPS also induced the apoptosis of the cervical cancer cells by changing the nuclear morphology and decreasing the mitochondrial membrane potential. Furthermore, the EPS-induced apoptosis was associated with the regulation of Bcl-2 family protein expression. In particular, the pro-apoptotic protein Bak-1 was increased and anti-apoptotic protein Bcl-2 was decreased with the increasing concentration at certain range of EPS. These results indicated that EPS might induce the apoptosis of cervical cancer cells through an intrinsic apoptotic pathway, and EPS may act as potent antitumor agents.

The role of BIM-EL and BCL2-α on the efficacy of erlotinib and gefitinib in lung cancer

Tyrosine kinase inhibitors (TKI), erlotinib and gefitinib are small molecule inhibitors which are used for the treatment of lung cancer. But, the development of drug resistance has been reported as one of the major setbacks in oncology. This study focused on the mechanisms leading to secondary resistance by assessing the gene expression of BCL2 family proteins which are associated with the intrinsic apoptotic signaling pathway. 8 genes were investigated in erlotinib and gefitinib treated cells by real time PCR and protein analysis by western blotting. The cells were exposed to the test drugs 48h prior to RNA or protein isolation. It was observed that BIM-EL, a pro-apoptotic protein was up-regulated in cells sensitive to the drugs but not in the resistant cells. On the other hand BCL2-α, an anti-apoptotic protein was up-regulated in the resistant cells and not in the sensitive cells. BCL2-α revealed a counter-regulation effect on BIM-EL and this effect is probably one of the causes of secondary resistance to erlotinib and gefitinib.

Abstract 342: Telomerase-dependent oncolytic adenovirus sensitizes human osteosarcoma cells to chemotherapy through Mcl-1 downregulation

Abstract Osteosarcoma is the most common malignant primary bone tumor. Despite advances in multi-agent chemotherapy, poor response to chemotherapy is one of the critical prognostic factors in osteosarcoma. Therefore, enhancement of chemosensitivity is one approach to improve the survival of osteosarcoma patients. We recently developed a telomerase-specific replication-competent oncolytic adenovirus, Telomelysin (OBP-301). A Phase I clinical trial in the U.S. showed the safety of OBP-301 in advanced cancer patients, and a Phase I/II clinical trial for malignant thoracic tumors is currently undergoing. We recently confirmed the antitumor effect of OBP-301 monotherapy in human osteosarcoma cells. In this study, we investigated the chemosensitizing effect of OBP-301 in human osteosarcoma cells and the molecular mechanism in the OBP-301-mediated enhancement of cell death. We used four human osteosarcoma cell lines, HOS, MNNG/HOS, 143B and SaOS-2. OBP-301 is an attenuated adenovirus, in which the hTERT promoter drives the expression of E1 gene, and causes tumor-selective lysis in a variety of human malignant tumor cells with telomerase activity. OBP-301 infection enhanced the cytotoxic effect of chemotherapeutic agents, cisplatin and doxorubicin, that are commonly used for the treatment of osteosarcomas. The calculation of combination index revealed the synergistic effects in all human osteosarcoma cell lines. Combination of OBP-301 increased apoptosis in the chemotherapeutic agents-treated cells. To clarify the molecular mechanism for the chemosensitizing effect of OBP-301, the expression of Bcl-2 family proteins, which are critical regulators of apoptosis, were investigated. In OBP-301-infected MNNG/HOS and SaOS-2 cells, the expression level of Mcl-1 was markedly decreased by OBP-301 infection. Downregulation of Mcl-1 expression by siRNA enhanced the chemotherapeutic agents-induced apoptosis. Moreover, combination therapy of chemotherapeutic agents with OBP-301 significantly suppressed tumor growth in a subcutaneous xenograft tumor model compared to monotherapy with chemotherapeutic agents or OBP-301. Anti-apoptotic Mcl-1 protein has been shown to be frequently overexpressed in human sarcomas. Overexpression of anti-apoptotic proteins is an important factor to prevent chemotherapy-induced apoptosis in cancer. We demonstrated the involvement of Mcl-1 suppression in the chemosensitizing effect of OBP-301 in human osteosarcoma cells. These results suggest that Mcl-1 is a critical target for improvement of the chemosensitivity in human osteosarcoma cells and the combination of chemotherapy with OBP-301 may be a novel therapeutic strategy for osteosarcoma patients. Citation Format: Shuhei Osaki, Toshinori Omori, Hiroshi Tazawa, Joe Hasei, Yasuaki Yamakawa, Tsuyoshi Sasaki, Toshiyuki Kunisada, Yasuo Urata, Toshifumi Ozaki, Toshiyoshi Fujiwara. Telomerase-dependent oncolytic adenovirus sensitizes human osteosarcoma cells to chemotherapy through Mcl-1 downregulation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 342. doi:10.1158/1538-7445.AM2014-342

IKK-induced NF-κB1 p105 proteolysis is critical for B cell antibody responses to T cell-dependent antigen.

The importance of IκB kinase (IKK)-induced proteolysis of NF-κB1 p105 in B cells was investigated using Nfkb1(SSAA/SSAA) mice, in which this NF-κB signaling pathway is blocked. Nfkb1(SSAA) mutation had no effect on the development and homeostasis of follicular mature (FM) B cells. However, analysis of mixed bone marrow chimeras revealed that Nfkb1(SSAA/SSAA) FM B cells were completely unable to mediate T cell-dependent antibody responses. Nfkb1(SSAA) mutation decreased B cell antigen receptor (BCR) activation of NF-κB in FM B cells, which selectively blocked BCR stimulation of cell survival and antigen-induced differentiation into plasmablasts and germinal center B cells due to reduced expression of Bcl-2 family proteins and IRF4, respectively. In contrast, the antigen-presenting function of FM B cells and their BCR-induced migration to the follicle T cell zone border, as well as their growth and proliferation after BCR stimulation, were not affected. All of the inhibitory effects of Nfkb1(SSAA) mutation on B cell functions were rescued by normalizing NF-κB activation genetically. Our study identifies critical B cell-intrinsic functions for IKK-induced NF-κB1 p105 proteolysis in the antigen-induced survival and differentiation of FM B cells, which are essential for T-dependent antibody responses.