Apoptosis In Jurkat Cells Research Articles

LukS-PV induces apoptosis in acute myeloid leukemia cells mediated by C5a receptor.

LukS‐PV is one of the two components of Panton‐Valentine leucocidin (PVL). Our previous study showed that LukS‐PV can induce apoptosis in human acute myeloid leukemia (AML) THP‐1 and HL‐60 cells. C5aR (C5a receptor) is the receptor for PVL, but whether C5aR plays a key role in LukS‐PV induced apoptosis is unclear. The aim of this study was to establish whether C5aR plays a physiological role in apoptosis of leukemia cells induced by LukS‐PV. We investigated the role of C5aR in leukemia cell apoptosis induced by LukS‐PV by pretreatment of THP‐1 and HL‐60 cells with C5aR antagonist and transfection to knockdown C5aR in THP‐1 cells or overexpress C5aR in Jurkat cells before treatment with LukS‐PV. Cell apoptosis was analyzed by staining with Annexin V/propidium iodide or Annexin V‐PE/7‐AAD. Mitochondrial membrane potential (MMP) was determined using JC‐1 dye. The expression of apoptosis‐associated genes and proteins was identified by qRT‐polymerase chain reaction and Western blotting analysis, respectively. As the C5aR antagonist concentration increased, the rate of apoptosis induced by LukS‐PV decreased, the MMP increased, and expression of pro‐apoptotic Bax and Bak genes and proteins was downregulated while that of anti‐apoptotic Bcl‐2 and Bcl‐x genes and proteins was upregulated. Knockdown of C5aR also decreased LukS‐PV–induced THP‐1 cell apoptosis. LukS‐PV did not induce apoptosis of Jurkat cells, which have no endogenous C5aR expression; however, LukS‐PV did induce apoptosis in Jurkat cells after overexpression of C5aR. Correspondingly, the MMP decreased and Bax and Bak were upregulated while Bcl‐2 and Bcl‐x were downregulated. LukS‐PV can induce apoptosis in AML cells by targeting C5aR. C5aR may be a potential therapeutic target for AML and LukS‐PV is a candidate targeted drug for the treatment of AML.

TimosaponinA‑III induces autophagy of T‑cell acute lymphoblastic leukemia Jurkat cells via inhibition of the PI3K/Akt/mTOR pathway.

TimosaponinA‑III (TAIII) is a saponin isolated from anemarrhena asphodeloides and possesses the inhibitory effect on proliferation of multiple tumor cells. In the present study, the antitumor effect of TAIII and its underlying molecular mechanisms were investigated invitro in T‑cell acute lymphoblastic leukemia (T‑ALL) Jurkat cells. The results demonstrated that TAIII inhibits the viability of Jurkat cells in a time‑and dose‑dependent manner, and induces apoptosis of Jurkat cells in a dose‑dependent manner. Transmission electron microscopy demonstrated the formation of numerous autophagosomes in TAIII‑treated Jurkat cells. Furthermore, monodansylcadaverine (MDC)‑labeled autophagic vacuoles were observed following TAIII treatment by an inverted fluorescence microscope and MDC accumulation increased notably in TAIII treatment groups in a concentration‑dependent manner. B‑cell lymphoma‑2 (Bcl‑2)‑associatedX (Bax) was upregulated while Bcl‑2 was reduced following TAIII treatment, indicating that the pro‑apoptotic mechanism of TAIII may be associated with upregulation of Bax. Further investigation revealed that TAIII promotes the expression of autophagy‑associated proteins Beclin1 and LC3‑II, and inhibits the phosphoinositide3‑kinase/Akt/mechanistic target of rapamycin kinase pathway. The present study revealed that the antitumor activity of TAIII was primarily achieved by the induction of cell apoptosis and autophagy, indicating a promising potential as a novel effective reagent against T‑ALL.

Raman spectrum spectral imaging revealing the molecular mechanism of Berberine-induced Jurkat cell apoptosis and the receptor-mediated Berberine delivery system.

Berberine (BBR), a traditional Chinese herb extract medicine, reveals some anticancer effects in leukemia, but it remains controversial about the molecular mechanism of BBR-induced leukemia cell apoptosis. In this study, combining Raman spectrum and spectral imaging, both the biochemical changes of BBR-induced Jurkat cell apoptosis and the precise distribution of BBR in single cell are presented. In contrast, we also show the corresponding results of Jatrorrhizine (JTZ) and Palmatine (PMT), two structural analogues of BBR. It is found that all three structural analogues can induce cell apoptosis by breaking DNA and the main action sites are located in phosphate backbone and base pair groups, but their action on cell cycle are different, in which BBR leads to the S phase arrest while JTZ and PMT are on the G2 phase arrest. Moreover, from the Raman spectra of DNA treated with different drugs, we find that the content of phosphate backbone and base pair groups in BBR-treated DNA are larger than those in JTZ or PMT. And this result reflects the strong capability of BBR breaking DNA backbone relative to JTZ or PMT, suggesting that the existence of methylene-dioxy on the 2, 3 units of A ring on the quinoline ring can greatly enhance the capability of BBR breaking DNA backbone, so the action effect of BBR-induced Jurkat cell apoptosis is better than those of PMT or JTZ. Further, by using Raman spectral imaging approach, we achieve the precise distribution of BBR in single cell, it is found that the receptor-mediated BBR targeting delivery based single-wall carbon nanotube and folic acid (SWNT/FA) reveals excellent performance in BBR targeting delivery relative to the conventional BBR diffusion approach. Importantly, these results demonstrate that Raman spectrum and spectral imaging should be a powerful tool to study the molecular mechanism of drug-induced cell apoptosis and evaluate the efficiency of drug delivery system.

Design and synthesis of various quinizarin derivatives as potential anticancer agents in acute T lymphoblastic leukemia.

A series of quinizarin derivatives containing quaternary ammonium salts and/or thiourea groups were synthesized and their anticancer activities against leukemia cell lines have been tested. Results showed that most of quinizarin derivatives could inhibit the proliferation of leukemia cells. Among these derivatives, compound 3 showed good inhibition activity against various leukemia cells with IC50 values ranging from 0.90 ± 2.55 μM to 10.90 ± 3.66 μM. At the same time, compound 3 also inhibited the growth of human embryonic kidney-293 cell (HEK-293). Molt-4 and Jurkat cells, acute T lymphoblastic leukemia (T-ALL) cell lines, were selected to reveal potential anticancer mechanism of compound 3. Compound 3 inhibited the proliferation of Molt-4 and Jurkat cells in a dose- and time-dependent manner and led to a marked G0/G1 phase arrest. Analysis of Annexin V-APC and intracellular reactive oxygen species (ROS) level by flow cytometry showed that compound 3 induced significant apoptosis in Molt-4 and Jurkat cells. Western blotting assay showed that compound 3 activated the caspase-dependent apoptosis pathway and induced the degradation of Bcl-2 and c-myc protein.

Simultaneous polychromatic flow cytometric detection of multiple forms of regulated cell death

Currently the study of Regulated Cell Death (RCD) processes is limited to the use of lysed cell populations for Western blot analysis of each separate RCD process. We have previously shown that intracellular antigen flow cytometric analysis of RIP3, Caspase-3 and cell viability dye allowed the determination of levels of apoptosis (Caspase-3+ ve/RIP3− ve), necroptosis (RIP3Hi + ve/Caspase-3− ve) and RIP1-dependent apoptosis (Caspase-3+ ve/RIP3+ ve) in a single Jurkat cell population. The addition of more intracellular markers allows the determination of the incidence of parthanatos (PARP), DNA Damage Response (DDR, H2AX), H2AX hyper-activation of PARP (H2AX/PARP) autophagy (LC3B) and ER stress (PERK), thus allowing the identification of 124 sub-populations both within live and dead cell populations. Shikonin simultaneously induced Jurkat cell apoptosis and necroptosis the degree of which can be shown flow cytometrically together with the effects of blockade of these forms of cell death by zVAD and necrostatin-1 have on specific RCD populations including necroptosis, early and late apoptosis and RIP1-dependent apoptosis phenotypes in live and dead cells. Necrostatin-1 and zVAD was shown to modulate levels of shikonin induced DDR, hyper-action of PARP and parthanatos in the four forms of RCD processes analysed. LC3B was up-regulated by combined treatment of zVAD with chloroquine which also revealed that DNA damage was reduced in live cells but enhanced in dead cells indicating the role of autophagy in maintaining cell health. This approach to RCD research should be a great advance to understanding the mechanisms of drugs and their effects upon RCD populations.

Effect of microRNA-153 targeting phosphatidylinositol 3 kinase/serine-threonine protein kinase signaling pathway on proliferation in acute lymphoblastic leukemia cell

Objective To investigate the effect of microRNA (miRNA, miR)-153 on the proliferation and apoptosis of in human acute lymphoblastic leukemia (ALL) cell line Jurkat cells by phosphatidylinositol 3 kinase (PI3K)/serine-threonine protein kinase (Akt) pathway. Methods After miR-153 mimics (miR-153 mimics group) and miR-153 inhibitor (miR-153 inhibitor group) were transfected into Jurkat cells, cell proliferation, cycle and apoptosis. was detected; the expression of miR-153, PI3K and Akt mRNA and protein was measured; whether PI3K was the target gene of miR-153. was confirmed. Results Compared with the negative control group, the expression of miR-153 in the miR-153 mimics group was significantly increased by approximately 10-fold (t=39.596, P<0.01), and the expression of miR-153 was significantly decreased in the miR-153 inhibitor group (t=14.651, P<0.01). The activity of the cells in the miR-153 mimics group was significantly decreased (t=10.931, P<0.01), and the activity of the miR-153 inhibitor group was significantly increased (t=7.640, P<0.01). The expression of PI3K total protein, PI3K mRNA and p-Akt in the miR-153 mimics group was significantly decreased (t=7.161, P<0.01; t=6.684, P<0.01; t=10.769, P<0.01), and the expression of PI3K total protein, PI3K mRNA and p-Akt in the miR-153 inhibitor group was significantly increased (t=3.998, P<0.05; t=8.902, P<0.01; t=7.078, P<0.01). The proportion of G0/G1 phase cells increased significantly, while the S phase and G2/M phasecells decreased significantly (t=3.786, P<0.05; t=3.012, P<0.05; t=4.948, P<0.01) in the miR-153 mimics group; the G0/G1 phase cells decreased significantly, and the proportion of cells in S phase and G2/M phase increased significantly (t=5.356, P<0.01; t=3.055, P<0.05; t=3.893, P<0.05) in the miR-153 inhibitor group. The apoptosis rate of the miR-153 mimics group was significantly increased (t=4.673, P<0.05), while the apoptotic rate of the miR-153 inhibitor group was significant decline (t=5.618, P<0.01). Compared to the empty plasmid group, the relative luciferase activity of 3’untranslated regions (3’UTR) plasmid group was significantly reduced (t=7.925, P<0.01). Conclusion MiR-153 can directly target PI3K/Akt signaling pathway and regulate Jurkat cell proliferation and apoptosis. Key words: Acute lymphoblastic leukemia; MicroRNA-153; Phosphatidylinositol 3 kinase/serine-threonine protein kinase signaling pathway

P114 MCH LINKS IMMUNOMETABOLSIM TO INTESTINAL INFLAMMATION

Melanin concentrating hormone (MCH) was first identified as a hypothalamic neuropeptide regulating feeding behavior and energy balance. The MCH receptor, MCHR1, is present in brain as well as in several peripheral tissues including the gastrointestinal tract where its role is yet to be established. Increased MCH and MCHR1 expression in the mucosa of patients with inflammatory bowel disease (IBD) implies a role of MCH in disease pathogenesis. Our previous studies have shown that MCH-deficient mice develop attenuated colitis, a phenotype that was recapitulated when mice were treated with an anti-MCH antibody. The exact mechanisms by which MCH exerts proinflammatory effects remain under investigation, as well as the cell types involved and have been the focus of the present study. We found MCHR1 upregulation in CD4+ T cells isolated from the lamina propria of patients with Crohn’s disease, in contrast to those derived from peripheral blood. In vitro, MCHR1 was induced upon activation of CD4+ T-cells. Furthermore, treatment with MCH of mucosal explants from patients with IBD resulted in increased cytokine secretion in the culture supernatant (IFNg, IL-17, IL-2, IL-6, IL8, MCP1, TNFa). Most importantly, metabolomics analysis of Jurkat cells, a T-cell line expressing high basal levels of MCHR1 receptor, revealed that treatment with MCH increased glutamine, glutamate and a-ketoglutarate levels 4-, 2.5-, and 3.5-fold, respectively, as well as those of acetyl-CoA (3-fold) while glycolytic intermediates remained unaltered. These findings imply engagement of a “reductive carboxylation” cycle in the presence of MCH, the fuel of which is a-ketoglutarate instead of glucose. The role of a-ketoglutarate in driving T-effector activation and differentiation is well established. In further support of these observations, stimulation with MCH resulted in upregulation of the glutamine transporter SLC1A5 that determines intracellular glutamine levels, as well those of its metabolites glutamate and a-ketoglutarate. In relation to the immune phenotype, MCH-induced metabolic shifts correlated with increased proliferation and reduced apoptosis of Jurkat cells, as well as increased IL-2 secretion. In a more relevant context, treatment of isolated CD4+ T cells with MCH under polarized conditions resulted in 70% increase of IL-17+ cells, in contrast to 32% decrease of IL-4+ and 25% decrease of Foxp3+ cells. Collectively, these findings further support a deleterious effect of aberrant MCH signaling in IBD and potentially illustrate a new target in IBD therapeutics.

Attenuating the abnormally high expression of AEBP1 suppresses the pathogenesis of childhood acute lymphoblastic leukemia via p53-dependent signaling pathway.

This study aimed to explore the candidate genes and their potential mechanism in childhood acute lymphoblastic leukemia (cALL). Differentially expressed genes (DEGs) were screened from GSE67684 (treatment), GSE28460 (relapse), and GSE60926 (relapse). The expression of AEBP1 at different stages of cALL was analyzed followed by functional enrichment analysis of its co-expressed genes. Expression of AEBP1 was determined in different leukemia cell lines and knocked down in Jurkat cells. Cell behaviors as well as the expression of p53, Bax, and Bcl-2 were also evaluated after silencing AEBP1 in Jurkat cells. Two clusters: Profile 1 (downward) and Profile 26 (upward) were identified in GSE67684, and 53 Profile 1-specific DEGs were identified compared with DEGs in GSE28460 and GSE60926. AEBP1 was one of these genes and was significantly downregulated after treatment but upregulated in relapse samples. Functional enrichment analysis revealed that AEBP1 co-expressed genes were significantly enriched in GO terms including immune response, blood coagulation etc. and in the hematopoietic cell lineage and PI3K/Akt signaling pathways. AEBP1 was significantly increased in leukemia cell lines, especially in Jurkat cells, compared with the Pbmc cells. Silencing AEBP1 markedly reduced proliferation and induced cell cycle arrest in Jurkat cells, but also promoted apoptosis of Jurkat cells. Silencing AEBP1 also inhibited the expression of p53 and Bcl-2 but promoted Bax in Jurkat cells. AEBP1 was highly-expressed in the diagnosis and relapse cALL, and silencing AEBP1 significantly reduced proliferation but promoted apoptosis in Jurkat cells via a p53-dependent pathway.

P114 MCH LINKS IMMUNOMETABOLSIM TO INTESTINAL INFLAMMATION

Melanin concentrating hormone (MCH) was first identified as a hypothalamic neuropeptide regulating feeding behavior and energy balance. The MCH receptor, MCHR1, is present in brain as well as in several peripheral tissues including the gastrointestinal tract where its role is yet to be established. Increased MCH and MCHR1 expression in the mucosa of patients with inflammatory bowel disease (IBD) implies a role of MCH in disease pathogenesis. Our previous studies have shown that MCH-deficient mice develop attenuated colitis, a phenotype that was recapitulated when mice were treated with an anti-MCH antibody. The exact mechanisms by which MCH exerts proinflammatory effects remain under investigation, as well as the cell types involved and have been the focus of the present study. We found MCHR1 upregulation in CD4+ T cells isolated from the lamina propria of patients with Crohn’s disease, in contrast to those derived from peripheral blood. In vitro, MCHR1 was induced upon activation of CD4+ T-cells. Furthermore, treatment with MCH of mucosal explants from patients with IBD resulted in increased cytokine secretion in the culture supernatant (IFNg, IL-17, IL-2, IL-6, IL8, MCP1, TNFa). Most importantly, metabolomics analysis of Jurkat cells, a T-cell line expressing high basal levels of MCHR1 receptor, revealed that treatment with MCH increased glutamine, glutamate and a-ketoglutarate levels 4-, 2.5-, and 3.5-fold, respectively, as well as those of acetyl-CoA (3-fold) while glycolytic intermediates remained unaltered. These findings imply engagement of a “reductive carboxylation” cycle in the presence of MCH, the fuel of which is a-ketoglutarate instead of glucose. The role of a-ketoglutarate in driving T-effector activation and differentiation is well established. In further support of these observations, stimulation with MCH resulted in upregulation of the glutamine transporter SLC1A5 that determines intracellular glutamine levels, as well those of its metabolites glutamate and a-ketoglutarate. In relation to the immune phenotype, MCH-induced metabolic shifts correlated with increased proliferation and reduced apoptosis of Jurkat cells, as well as increased IL-2 secretion. In a more relevant context, treatment of isolated CD4+ T cells with MCH under polarized conditions resulted in 70% increase of IL-17+ cells, in contrast to 32% decrease of IL-4+ and 25% decrease of Foxp3+ cells. Collectively, these findings further support a deleterious effect of aberrant MCH signaling in IBD and potentially illustrate a new target in IBD therapeutics.

Isolation and Stimulation of Peritoneal Macrophages withApoptotic Jurkat Cells to Produce IL-10.

Clearance of apoptotic cells by macrophages is critical to ensuring cellular homeostasis and suppression of autoimmunity. Macrophage recognition of apoptotic cells triggers an anti-inflammatory response, which is mediated by the release of IL-10, TGF-β etc. with concurrent inhibition of pro-inflammatory cytokines (such as TNFα, IL-12, IL-1β). To characterize cytokine profile produced by macrophages during phagocytosis of apoptotic cells, we developed an effective, more physiologic system using isolated murine peritoneal macrophages and T-lymphocyte cell line Jurkat as a source of apoptotic cells. Apoptosis of Jurkat cells is induced with staurosporine, a protein kinase C (PKC) inhibitor and detected by Annexin V/propidium iodide staining. This in vitro assay demonstrates that murine peritoneal macrophages produce large amounts of IL-10 following exposure to apoptotic Jurkat cells.

MicroRNA-146a Promotes Growth of Acute Leukemia Cells by Downregulating Ciliary Neurotrophic Factor Receptor and Activating JAK2/STAT3 Signaling.

PurposeAcute leukemia (AL) is classified as acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). This study aimed to investigate the effect of miR-146a on childhood AL and its underlying molecular mechanisms.Materials and MethodsBone marrow samples were obtained from 39 AL children and 10 non-cancer controls. The expressions of miR-146a and ciliary neurotrophic factor receptor (CNTFR) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in ALL and AML pediatric patients, as well as ALL (Jurkat) and AML (HL-60) cells. Correlations between miR-146a and clinical indicators were explored. A targeting relationship between miR-146a and CNTFR was detected by dual luciferase reporter gene assay. Cell proliferation, apoptosis, migration, and invasion of Jurkat and HL-60 cells were measured by MTT assay, flow cytometry, and transwell assay, respectively. LIF expression was detected by qRT-PCR in Jurkat and HL-60 cells. The expression of p-JAK2, JAK2, p-STAT3, and STAT3 in HL-60 cells was measured by Western blot.ResultsmiR-146a was increased in ALL and AML pediatric patients, while CNTFR was decreased. miR-146a expression was associated with immunophenotype, karyotype, fusion gene, and SIL-TAL1. CNTFR was a target gene of miR-146a. miR-146a could promote cell proliferation, migration, and invasion, as well as inhibit cell apoptosis in Jurkat and HL-60 cells by downregulating CNTFR. Meanwhile, miR-146a inhibited the expression of LIF and activated JAK2/STAT3 pathway by downregulating CNTFR.ConclusionmiR-146a could promote the proliferation, migration, and invasion and inhibit the apoptosis of AL Jurkat and HL-60 cells by downregulating CNTFR and activating the JAK2/STAT3 pathway.

Effects of annexin A1 on apoptosis and cell cycle arrest in human leukemic cell lines.

Recent studies suggest that annexin A1 (ANXA1) promotes apoptosis in cancerous cells. This study aims to investigate the effects of ANXA1 on apoptosis and cell cycle arrest in K562, Jurkat and U937 cells and peripheral blood mononu-clear cells (PBMC). Cells were treated with ANXA1 and cyclophosphamide prior to flow cytometry analysis for apoptosis and cell cycle arrest induction. At 2.5µM, ANXA1 induced significant apoptosis in K562 (p ≤ 0.001) and U937 (p ≤ 0.05) cells, with EC50 values of 3.6 and 3.8 µM, respectively. In Jurkat cells, induction was not significant (EC50, 17.0 µM). No significant apoptosis induction was observed in PBMC. ANXA1 caused cycle arrest in the G0/G1 phase in K562 and U937 cells with p ≤ 0.001 for both, and (p ≤ 0.01) for Jurkat cells. ANXA1 induced apoptosis and cycle arrest in the G0/G1 phase in K562 and U937 cells, causing only cell cycle arrest in Jurkat cells.

Meripilus giganteus ethanolic extract exhibits pro-apoptotic and anti-proliferative effects in leukemic cell lines

BackgroundThe interest towards botanicals and plant extracts has strongly risen due to their numerous biological effects and ability to counteract chronic diseases development. Among these effects, chemoprevention which represents the possibility to counteract the cancerogenetic process is one of the most studied. The extracts of mushroom Meripilus giganteus (MG) (Phylum of Basidiomycota) showed to exert antimicrobic, antioxidant and antiproliferative effects. Therefore, since its effect in leukemic cell lines has not been previously evaluated, we studied its potential chemopreventive effect in Jurkat and HL-60 cell lines.MethodsMG ethanolic extract was characterized for its antioxidant activity and scavenging effect against different radical species. Moreover, its phenolic profile was evaluated by HPLC-MS-MS analyses. Flow cytometry (FCM) analyses of Jurkat and HL-60 cells treated with MG extract (0–750 μg/mL) for 24–72 h- allowed to evaluate its cytotoxicity, pro-apoptotic and anti-proliferative effect. To better characterize MG pro-apoptotic mechanism ROS intracellular level and the gene expression level of FAS, BAX and BCL2 were also evaluated. Moreover, to assess MG extract selectivity towards cancer cells, its cytotoxicity was also evaluated in human peripheral blood lymphocytes (PBL).ResultsMG extract induced apoptosis in Jurkat and HL-60 cells in a dose- and time- dependent manner by increasing BAX/BCL2 ratio, reducing ROS intracellular level and inducing FAS gene expression level. In fact, reduced ROS level is known to be related to the activation of apoptosis in leukemic cells by the involvement of death receptors. MG extract also induced cell-cycle arrest in HL-60 cells. Moreover, IC50 at 24 h treatment resulted 2 times higher in PBL than in leukemic cell lines.ConclusionsOur data suggest that MG extract might be considered a promising and partially selective chemopreventive agent since it is able to modulate different mechanisms in transformed cells at concentrations lower than in non-transformed ones.

Effect and mechanism of Solanine on proliferation and apoptosis of Jurkat cells

Objective To explore the effect of proliferation and apoptosis of Solanine on acute T lymphocyte leukemia (T-ALL) Jurkat cells and its mechanism. Methods After treated with different concentrations of Solanine, the proliferation of Jurkat cells was detected by CCK-8 assay, and the effect of Solanine on apoptosis of Jurkat cells were detected by flow cytometry.The expression of Bcl-2 and Bax in Jurkat cells were detected by Western blot, and the expression levels of Bcl-2 mRNA and Bax mRNA were detected by real-time fluorescence quantitative polyme-rase chain reaction. Results CCK-8 assay showed that Solanine significantly inhibited the proliferation of Jurkat cells in a dose-and time-dependent manner. The results of flow cytometry showed that the apoptosis rates of Jurkat cells treated with Solanine for 24 h were (2.40±0.98)%, (28.43±4.86)%, (41.56±1.87)%, respectively, in a dose-dependent manner. Western blot showed that Solanine could increase the expression of Bax and decrease the expression of Bcl-2 in Jurkat cells, and they all were dose-dependent. Conclusion Solanine can significantly inhibit the proliferation and induce apoptosis of Jurkat cells. The mechanism is related to the up-regulation of Bax expression and down-regulation of Bcl-2 expression. Key words: Solanine; Jurkat cell; Proliferation; Apoptosis

Knockdown of MAML1 inhibits proliferation and induces apoptosis of T-cell acute lymphoblastic leukemia cells through SP1-dependent inactivation of TRIM59.

Notch exerts important functions in cell proliferation, survival, and differentiation, which plays a critical role in tumor development when aberrantly activated. Mastermind-like protein 1 (MAML1) has been functioning as crucial coactivators of Notch receptors and is required for stable formation of Notch transcriptional complexes. However, the mechanism whereby MAML1 induces T-cell acute lymphoblastic leukemia (T-ALL) tumorigenesis is largely unknown. The CCK-8 and flow cytometry assay were performed to examine the effect of MAML1 knockdown on T-ALL cell proliferation, apoptosis, and cell cycle. The expression of MAML1, cell cycle, and apoptosis-related gene, as well as TRIM family members and specific protein 1 (SP1) was measured by western blot analysis and qPCR. Our results showed that MAML1 knockdown significantly inhibited cell proliferation and induced G0/G1 cell cycle arrest and apoptosis in Jurkat and MOLT-4 cells. Cell cycle and apoptosis-related gene expression, including CDK2, Bcl-2, Bax, and Bad, was modified by the MAML1 knockdown. MAML1 knockdown obviously inhibited the CDK2 and Bcl-2 expression and increased the Bax, p53, and Bad expression. Moreover, the TRIM family members, including TRIM13, TRIM32, TRIM44, and TRIM59, were significantly decreased by the MAML1 knockdown, with the highest decrease detected in TRIM59 expression. Interesting, overexpression of SP1 not only increased the expression of MAML1 and TRIM59, but also promoted the promoter activation of TRIM59. Taken together, knockdown of MAML1 inhibits proliferation and induces apoptosis of T-ALL cells through SP1-dependent inactivation of TRIM59, and therefore suggest that MAML1-SP1-TRIM59 axis may serve as potentially interesting therapeutic targets for treatment of T-ALL.

Knockdown of the Hippo transducer YAP reduces proliferation and promotes apoptosis in the Jurkat leukemia cell

Leukemia and lymphoma are common hematological malignancies in children and young adults, which pose a tremendous threat to the survival of these young patients worldwide, despite availability of various effective treatments. The Hippo pathway is a novel-signaling pathway that regulates organ size, cell proliferation, apoptosis and tumorigenesis. The chief component of this pathway is the transducer yes-associated protein (YAP) which is over-expressed in numerous categories of tumors. However, little is known about the effect of YAP in hematological malignancies. In the present study, YAP expression was screened in several leukemia and lymphoma cell lines, and high YAP expression was demonstrated in Jurkat cells. To further unravel its effect on the biological behavior of Jurkat cells, lentivirus transduced short hairpin RNA (shRNA) technique was used to silence YAP. As expected, the YAP-specific shRNA dramatically inhibited YAP expression at the mRNA and protein levels. Reduced leukemia cell proliferation and increased cell apoptosis were demonstrated in YAP knockdown Jurkat cells. It was also demonstrated that YAP knockdown resulted in deregulated expression of a cluster of downstream genes crucial to cell proliferation or apoptosis, including protein kinase B, B-cell lymphoma 2 (BCL2) and BCL2 like protein 1. Consequently, the results of the present study established that suppression of YAP expression serves an important role in Jurkat cell proliferation and apoptosis, which may serve as a potential therapeutic target.

Ubiquitin and regulation of apoptosis in Jurkat cells

Introduction.One of the crucial tasks in medicine is studying the molecular mechanisms of selective management of tumor cell apoptosis following conformational changes in protein molecules (ubiquitination).The purpose of the study. The aim of the project is to establish the role of ubiquitin and ubiquitinligase in dexamethasone-induced apoptosis in Jurkat cells.Materials and methods.The study was carried out on the Jurkat tumor cell line (intact cells and cells cultured in the presence of an apoptosis inducer dexamethasone in the final concentration of 10 µmol. In intact and dexamethasone-affected Jurkat cells, implementation of apoptosis and the amount of FAS-, TNF Receptor 1 and cells with reduced mitochondrial membrane potential were assessed by flow cytometry using FITC-conjugated Annexin V and Propidium Iodide. The levels of NF-κB, Apaf-1, ubiquitin and ubiquitin ligase were determined by Western blot analysis. The activity of caspase-3 was measured by spectrofluorometry.Results.When adding the apoptosis inducer dexamethasone to the Jurkat cell culture, we registered a fall in the concentration of ubiquitin and a rise in the level of ubiquitinligase against the backdrop of activated receptor(an increase in the amount of Annexin V positive cells, FASand TNF Receptor 1) and mitochondrialmediated (an increase in the number of cells with reduced mitochondrial membrane potential and elevation of Apaf-1 level) pathways of apoptosis, as opposed to the intact cell culture. We estimated the completion of apoptosis by determining the activity of caspase-3 in the investigated tumor cells.Conclusion.The obtained findings allow the conclusion that ubiquitination of regulatory and effector proteins in programmed cell death is one of the molecular mechanisms that regulates and selectively controls apoptosis in Jurkat cells.

HIV-1 Tat-induced bystander apoptosis in Jurkat cells involves unfolded protein responses.

The HIV transactivator protein (Tat) is a multifunctional protein that plays a critical role in viral replication and contributes to several pathological symptoms of HIV-1 infection, which has the loss of CD4+ T lymphocytes as one of its hallmark features. It has been shown that endoplasmic reticulum (ER) stress, including viral infections, is implicated in cellular dysfunction and cell death through activation of the unfolded protein response (UPR). Here, we demonstrate that the bystander stimulus of Tat on Jurkat cells resulted in time-dependent overexpression of major UPR markers including ER chaperone BiP, ER stress sensors ATF6, PERK, and IRE1, as well as an increase in levels of downstream mediators eIF2α, ATF4, XBP-1, and proapoptotic factors CHOP, GADD34, and BIM. This upregulation of UPR mediators was accompanied by decreased cell viability and increased apoptosis as evidenced by blue trypan dye exclusion and flow cytometry assays, respectively. Furthermore, we found that the Tat-associated apoptosis of Jurkat cells led to the loss of mitochondrial membrane potential and caspase-12 and -3 activation. Taken together, these results suggest that the exposure of HIV-1 Tat leads to ER stress/UPR triggering which in turn contributes to apoptotic death in Jurkat cells. SIGNIFICANCE OF THE STUDY: In the present work, we provide a substantial insight into the link between ER impairment and apoptotic death following a bystander HIV Tat stimulus, revealing an underlying ER-mediated apoptotic mechanism which could explain the continuous depletion of uninfected CD4+ T lymphocytes observed in HIV-related disease. Our findings reinforce the relevance of ER stress molecular responses in the course of HIV infection and may afford valuable information for the development of new therapeutic strategies to avoid CD4+ T lymphocyte loss and other disorders induced by circulant Tat.

Arsenic trioxide induces the apoptosis and decreases NF-κB expression in lymphoma cell lines.

Lymphoma is a type of cancer that develops from certain immune system cells. Arsenic trioxide (ATO) has attracted wide attention owing to its antitumor activities. However, the role of ATO in tumorigenesis and progression remains to be investigated. In the present study, the antitumor function of ATO was investigated in in lymphoma Raji and Jurkat cell lines and the effect of ATO on nuclear factor (NF)-κB expression levels. A Cell Counting kit-8 assay was used to assess cellular proliferation and the degree of cell apoptosis was measured by flow cytometric analysis; these assays demonstrated that ATO inhibited proliferation and promoted the apoptosis of Raji and Jurkat cells in a dose- and time-dependent manner. Western blot analysis revealed that ATO treatment affected the expression of apoptosis-associated proteins by downregulating the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2) and upregulating the pro-apoptotic protein Bcl-2-associatedX and the degree of caspase-3 cleavage. In addition, reverse transcription-quantitative polymerase chain reaction and western blot analysis showed that the mRNA and protein expression levels of NF-κB were downregulated significantly following treatment with 2 µM ATO for 24, 48 and 72 h in the two cell lines. Additionally, immunofluorescence staining indicated that NF-κB expression diminished following ATO treatment in a time-dependent manner. These data indicated that ATO inhibited the proliferation of lymphoma cells by inducing cell apoptosis, which may be associated with the inhibition of the NF-κB signaling pathway. The findings of the present study may lay the foundation for developing a personalized medicine strategy using ATO via targeting of the NF-κB signaling pathway in lymphoma.

In vitro combinatorial anti-proliferative and immunosuppressive effects of Brucea javanica extract with CX-4945 and imatinib in human T-cell acute lymphoblastic leukemia cells

Since 1970, the isolated and identified components of Brucea javanica (L.) Merr. have been known to contain anticancer effects, particularly antileukemic effect. In this study, the inhibitory effect of Brucea javanica (BJ) on cell growth and inflammation was confirmed in human T-cell acute lymphocytic leukemia (T-ALL) cells, and its efficacy as an antileukemic agent was verified. Our results showed that BJ extract induced caspase-dependent apoptosis of T-ALL Jurkat cells through inhibition of the CK2-mediated signaling pathway, while exerting no significant cytotoxicity in normal peripheral blood mononuclear cells. Moreover, BJ extract suppressed the NF-κB signaling pathway, thus, inhibiting the interleukin (IL)-2 expression induced by phorbol 12-myristate 13-acetate (PMA) and phytohemagglutinin (PHA). Notably, combined treatment with BJ extract plus CX-4945 or imatinib exerted enhanced inhibitory effects on T-ALL cell growth and IL-2 production. Overall, these results suggest that BJ extract can be a potent therapeutic herbal agent for T-ALL treatment and prevention of IL-2 mediated inflammatory immune responses.