Synergistic Pre-Clinical Activity of Combined Epigenetic Therapy with the Novel Histone Methyltransferase EZH2 Inhibitor 3-Deazaneplanocin and Histone Deacetylase Inhibitor Panobinostat against Human AML Cells.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3356-3356
Author(s):  
Warren Fiskus ◽  
Yongchao Wang ◽  
Anand Jillella ◽  
Celalettin Ustun ◽  
Pace Johnston ◽  
...  
Keyword(s):  
Histone Deacetylase ◽  
Hox Genes ◽  
Histone Methyltransferase ◽  
Dna Methyltransferases ◽  
Parp Cleavage ◽  
Epigenetic Therapy ◽  
Clinical Activity ◽  
Gene Promoters ◽  
Core Proteins ◽  
Induced Apoptosis

Abstract Lysine specific histone methylation and deacetylation and DNA hypermethylation are involved in the epigenetic silencing of tumor suppressor genes (TSG), e.g., p15 and p16. The multi-protein complex PRC (polycomb repressive complex) 2 that contains the three core proteins EZH2, SUZ12 and EED, has intrinsic histone methyltransferase (HMTase) activity. This is mediated by the SET domain of EZH2, which induces tri-methylation (3Me) of lysine (K)-27 on histone H3, regulates the expression of HOX genes and promotes cell proliferation and aggressiveness of neoplastic cells. In the present studies we demonstrate that treatment with the S-adenosylhomocysteine hydrolase inhibitor 3-Deazaneplanocin A (DZNep) dose-dependently (200 nM to 2.0 uM) depletes EZH2, SUZ12 and EED levels, inhibits 3Me K27 on H3 while inducing K27 H3 acetylation in the cultured human AML HL60 and OCI-AML3 cells and in primary, patient-derived AML blasts. DZNep treatment also induced the levels of p16, p21, p27 and FBXO32 while depleting cyclin E and HOXA9 levels. Treatment with DZNep induced PARP cleavage activity of the caspases and apoptosis in the cultured and primary AML cells. DZNep promoted proteasomal degradation of EZH2 and SUZ12, since co-treatment with bortezomib significantly restored EZH2 and SUZ12 levels in the AML cells. We had previously reported that treatment with the pan-histone deacetylase (HDAC) inhibitor panobinostat (PS) (LBH589, Novartis Pharmaceutical Corp) also depletes the levels of EZH2, SUZ12 and EED in cultured and primary AML cells (Mol Cancer Ther.2006; 5:3096). Within the PRC2 complex, EZH2 bound and recruited the DNA methyltransferases DNMT1, and treatment with PS also disrupted the interaction of EZH2 with DNMT1, attenuated DNMT1 levels and its binding to the EZH2-targeted gene promoters, e.g., p16 and JunB. Here, we also demonstrate that, as compared to treatment with either agent alone, co-treatment with DZNep and PS caused more depletion of EZH2, SUZ12 and EED, more induction of p16, p21 and p27, as well as synergistically induced apoptosis of AML cells (combination indices < 1.0). Additionally, DZNep induced apoptosis of HL-60/LR cells that are resistant to HDACs including PS, as well as sensitized HL-60/LR cells to PS. Taken together, these findings indicate that targeting EZH2 and the PRC2 complex is an effective epigenetic therapy of AML that also overcomes resistance to HDAC inhibitors. Additionally, combined epigenetic therapy with DZNep and PS exerts synergistic in vitro activity against human AML cells, suggesting that this combination may be a promising novel treatment for AML.

scholarly journals Combined epigenetic therapy with the histone methyltransferase EZH2 inhibitor 3-deazaneplanocin A and the histone deacetylase inhibitor panobinostat against human AML cells

Blood ◽  
2009 ◽  
Vol 114 (13) ◽  
pp. 2733-2743 ◽  
Author(s):  
Warren Fiskus ◽  
Yongchao Wang ◽  
Arun Sreekumar ◽  
Kathleen M. Buckley ◽  
Huidong Shi ◽  
...  
Keyword(s):  
Histone Deacetylase ◽  
Histone Deacetylase Inhibitor ◽  
Hox Genes ◽  
Severe Combined Immunodeficiency ◽  
Histone H3 ◽  
Histone Methyltransferase ◽  
Epigenetic Therapy ◽  
Core Proteins ◽  
Deacetylase Inhibitor ◽  
Induced Apoptosis

Abstract The polycomb repressive complex (PRC) 2 contains 3 core proteins, EZH2, SUZ12, and EED, in which the SET (suppressor of variegation–enhancer of zeste-trithorax) domain of EZH2 mediates the histone methyltransferase activity. This induces trimethylation of lysine 27 on histone H3, regulates the expression of HOX genes, and promotes proliferation and aggressiveness of neoplastic cells. In this study, we demonstrate that treatment with the S-adenosylhomocysteine hydrolase inhibitor 3-deazaneplanocin A (DZNep) depletes EZH2 levels, and inhibits trimethylation of lysine 27 on histone H3 in the cultured human acute myeloid leukemia (AML) HL-60 and OCI-AML3 cells and in primary AML cells. DZNep treatment induced p16, p21, p27, and FBXO32 while depleting cyclin E and HOXA9 levels. Similar findings were observed after treatment with small interfering RNA to EZH2. In addition, DZNep treatment induced apoptosis in cultured and primary AML cells. Furthermore, compared with treatment with each agent alone, cotreatment with DZNep and the pan-histone deacetylase inhibitor panobinostat caused more depletion of EZH2, induced more apoptosis of AML, but not normal CD34+ bone marrow progenitor cells, and significantly improved survival of nonobese diabetic/severe combined immunodeficiency mice with HL-60 leukemia. These findings indicate that the combination of DZNep and panobinostat is effective and relatively selective epigenetic therapy against AML cells.

Anti-AML Activity of Combined Epigenetic Therapy with Novel DNMT1 Inhibitors SGI-110 or SGI-1036 and Histone Deacetylase Inhibitor Panobinostat.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3355-3355
Author(s):  
Warren Fiskus ◽  
Pace Johnston ◽  
Rajeshree Joshi ◽  
Rekha Rao ◽  
Celalettin Ustun ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Cell Cycle Progression ◽  
Dna Methyltransferases ◽  
Parp Cleavage ◽  
Epigenetic Therapy ◽  
Gene Promoters ◽  
Dna Hypermethylation ◽  
Dnmt Inhibitors ◽  
Protein Levels ◽  
Core Proteins

Abstract Lysine specific histone methylation and deacetylation and DNA hypermethylation are involved in the epigenetic silencing of tumor suppressor genes (TSG), e.g., p15 and p16. DNA methyltransferase (DNMT) inhibitors 5-azacytidine and 5-aza-2’-deoxycytidine demethylate the CpG dinucleotide islands in or near gene promoters, leading to derepression of TSGs in AML. SGI-110 (S110) (Cancer Res.2007; 67:6400) and SGI-1036 (SuperGen, Inc.) are novel, DNMT inhibitors, which also deplete DNMT1 levels. SGI-110 is a dinucleotide containing 5-aza-2’-deoxycytidine and SGI-1036 is a non-nucleoside heterocycle. The multi-protein complex PRC (polycomb repressive complex) 2 that contains the three core proteins EZH2, SUZ12 and EED, has intrinsic histone methyltransferase (HMTase) activity. This is mediated by the SET domain of EZH2, which induces trimethylation of histone H3 on lysine (K)-27. We recently reported that treatment with the pan-HDAC inhibitor panobinostat (LBH589, Novartis Pharmaceutical Corp) acetylates and inhibits the ATP binding and chaperone function of hsp90, as well as depletes the levels of EZH2, Suz12 and EED in cultured and primary AML cells (Mol Cancer Ther.2006; 5:3096). Within the PRC2 complex, EZH2 was shown to interact with and modulate the DNA methyltransferases DNMT1, DNMT3a and DNMT3b, which affects their binding to the EZH2-targeted gene promoters. In the present studies we determined the effects of SGI-110 or SGI-1036 and LBH589 on the PRC2 proteins EZH2 and SUZ12, and DNMT1, in the cultured (HL-60, OCI-AML3 and K562) and primary AML cells. Treatment with SGI-110 (0.5 to 2.0 μM) or SGI-1036 (0.5 and 1.0 μM) for 24 hours depleted protein levels of DNMT1 and EZH2 in the cultured and primary AML cells. SGI-110 and SGI-1036 promoted proteasomal degradation of DNMT1 and EZH2 since co-treatment with bortezomib significantly restored DNMT1 and EZH2 levels in the AML cells. Following treatment with SGI-110 or SGI-1036, bisulfite modification and methylation specific PCR demonstrated increase in unmethylated promoter DNA of p15 and JunB. This was associated with induction of the mRNA and protein levels of p15 and JunB, as well as caused inhibition of cell cycle progression (% of cells increased in G1 and increased in S phase) and colony growth in the soft agar. Treatment with 1.0 μM of SGI-110 or SGI-1036 also induced PARP cleavage activity of caspases and induced morphologic evidence of apoptosis in the AML cells. Co-treatment with 10 to 50 nM panobinostat enhanced SGI-110 or SGI-1036 mediated depletion of DNMT1 and EZH2, with more de-repression of the p15 and JunB and significant increase in apoptosis of AML cells. Collectively, these findings indicate that, SGI-110 and SGI-1036 deplete DNMT1 and EZH2 levels, as well as exert potent anti-AML activity. Additionally, combined epigenetic therapy consisting of SGI-110 or SGI-1036 in combination with panobinostat may represent a promising novel treatment of AML.

Combined Epigenetic Therapy with the Novel Histone Methyl Transferase EZH2 Inhibitor 3-Deazaneplanocin and Histone Deacetylase Inhibitor Panobinostat Exerts Synergistic Activity against Human Mantle Cell Lymphoma Cells

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3622-3622
Author(s):  
Warren Fiskus ◽  
Yongchao Wang ◽  
Anand Jillella ◽  
Pace Johnston ◽  
Rajeshree Joshi ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Mantle Cell Lymphoma ◽  
Histone Deacetylase ◽  
Cell Lymphoma ◽  
Parp Cleavage ◽  
Epigenetic Therapy ◽  
Synergistic Activity ◽  
Gene Promoters ◽  
Core Proteins ◽  
Mantle Cell

Abstract Lysine specific histone methylation and deacetylation and DNA hypermethylation are involved in the epigenetic silencing of tumor suppressor genes (TSG), e.g., p16 and JunB. The multi-protein complex PRC (polycomb repressive complex) 2 that contains the three core proteins EZH2, SUZ12 and EED, has intrinsic histone methyltransferase (HMTase) activity. This is mediated by the SET domain of EZH2, which induces tri-methylation (3Me) of lysine (K)-27 on histone H3, as well as promotes cell proliferation and aggressiveness of neoplastic cells. EZH2 is preferentially overexpressed in proliferating but not resting Mantle Cell Lymphoma (MCL) cells. In the present studies we demonstrate that treatment with the S-adenosylhomocysteine hydrolase inhibitor 3-Deazaneplanocin A (DZNep) dose-dependently (500 nM to 2.0 uM) depletes EZH2, SUZ12 and EED levels, as well as inhibits 3Me K27 on H3 while inducing K27 H3 acetylation. DZNep treatment also induces the levels of p21, p27, JunB and FBXO32, while depleting cyclin D1 and cyclin E levels in the cultured human MCL Jeko-1, MO2058 and Z138 cells and in primary patient-derived MCL cells. Treatment with DZNep induces PARP cleavage activity of the caspases and apoptosis in the cultured and primary MCL cells. DZNep promoted proteasomal degradation of EZH2 and SUZ12, since co-treatment with bortezpmib significantly restored EZH2 and SUZ12 levels in the MCL cells. We had previously reported that treatment with the pan-histone deacetylase (HDAC) inhibitor panobinostat (PS) (LBH589, Novartis Pharmaceutical Corp) depletes the levels of EZH2, SUZ12 and EED in cultured and primary AML cells (Mol Cancer Ther.2006; 5:3096). Within the PRC2 complex, EZH2 bound and recruited the DNA methyltransferases DNMT1, and treatment with PS also disrupted the interaction of EZH2 with DNMT1, attenuated DNMT1 levels and its binding to the EZH2-targeted gene promoters, e,g, JunB. Here, we also demonstrate that, PS treatment depletes DNMT1 levels and induces JunB levels in cultured MCL cells. As compared to treatment with either agent alone, co-treatment with DZNep and PS caused more depletion of EZH2 and SUZ12, but not of DNMT1, more induction of JunB, p21 and p27, as well as synergistically induced apoptosis of cultured MCL cells (combination indices < 1.0). Taken together, these findings indicate that DZNep and PS mediated targeting of EZH2 and the PRC2 complex is an effective epigenetic therapy of MCL, which also results in undermining several molecular determinants of MCL cell proliferation and survival. Additionally, combined epigenetic therapy with DZNep and PS exerts synergistic in vitro activity against human MCL cells, suggesting that this combination may be a promising novel treatment for MCL.

scholarly journals The Role of Histone Demethylases and DNA Methyltransferases in the Transcription Regulation of HOX Genes in PML-RARa+ AML Patients

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3921-3921
Author(s):  
Katerina Rejlova ◽  
Alena Musilova ◽  
Martina Slamova ◽  
Karel Fiser ◽  
Karolina Skvarova Kramarzova ◽  
...  
Keyword(s):  
Gene Expression ◽  
Hox Genes ◽  
Fold Increase ◽  
Dna Methyltransferases ◽  
Histone Mark ◽  
Gene Promoters ◽  
Histone Demethylases ◽  
Atra Treatment ◽  
Hox Gene

Abstract Homeobox genes (HOX) encode transcription factors that are frequently deregulated in leukemias. Our previous results showed that HOX gene expression differs among genetically characterized subtypes of pediatric acute myeloid leukemia (AML). Specifically, PML-RARa positive AML patients have overall lowest HOX gene expression which positively correlates with expression of histone 3 lysine 27 (H3K27) demethylases - JMJD3 and UTX and negatively with the expression of DNA methyltransferases - DNMT3a and DNMT3b. Interestingly, JMJD3 was already shown to be a direct target of PML-RARa protein (Martens, JH et al, 2010, Cancer Cell). From these findings we postulated a hypothesis that reduced levels of HOX genes in PML-RARa positive AML are a consequence of suppressed expression of histone demethylases resulting in increased H3K27 methylation and/or of elevated levels of DNMTs leading to de novoDNA methylation. We studied the role of histone demethylases and DNMTs in the regulation of HOX gene expression and the effect of treatment in PML-RARa positive cell lines (NB4 and ATRA-resistant clones NB4-LR2 and NB4-MR2). We treated NB4 cell line by all-trans retinoic acid (ATRA; 1uM), which was described to release the differentiation block caused by the presence of PML-RARa and to degrade the fusion protein. We observed that expression of particular HOX genes (HOXA1, HOXA3, HOXA4, HOXA5, HOXA7, HOXB4, HOXB6) measured by qPCR was significantly increased after ATRA treatment. While the level of JMJD3 was significantly increased upon ATRA treatment as well, the expression of UTX did not change. Furthermore, we detected significantly reduced expression of DNMT3b gene. To exclude a non-specific effect of ATRA, independent of PML-RARa, we used resistant clones LR2 and MR2 bearing mutations in retinoic acid-binding domain. HOX gene expression together with JMJD3, UTX and DNMT3b expression did not change upon ATRA treatment. These results confirm the PML-RARa-dependent regulation of HOX genes. To test the role of JMJD3 in the HOX gene expression regulation, we cultured NB4 cells with a specific inhibitor of histone demethylases, GSK-J4 (1 uM, 10 uM), in the presence of ATRA. The co-treatment caused significant decrease in the expression of studied HOX genes (HOXA1, HOXA3, HOXA5, HOXA7, HOXA10, HOXB4, HOXB6) in comparison to ATRA alone which supports the role of JMJD3 in the transcription regulation. Further, we performed chromatin immunoprecipitation (ChIP) to investigate if the changes of HOX gene expression upon ATRA and GSK-J4 treatment would correspond with changes of histone code on HOX gene promoter regions. ATRA treatment caused reduction of repressive histone mark (H3K27me3) on particular HOX gene promoters (HOXA1, HOXA3, HOXA5, HOXA7), by contrast, combinational treatment of ATRA and GSK-J4 reversed this effect. Accordingly, we detected that ATRA/GSK-J4 co-treatment reduced active histone mark H3K4me2. Next we were interested if JMJD3 inhibition would interfere with the differentiation effect of ATRA. As shown previously, ATRA treatment alone caused differentiation of NB4 cell line whereas the combination with GSK-J4 did not reduce the effect. Interestingly, in addition to differentiation it led cells to apoptosis. Combination of drugs (ATRA - 1uM, GSK-J4 - 1, 2, 5uM) increased significantly the percentage of dead cells in comparison to ATRA or GSK treatment alone (GSK-J4 alone vs in combination with ATRA, 1uM - 1.8 fold, 2uM - 2.2 fold, 5 uM - 2.3 fold increase). Next we measured apoptosis in resistant clones LR2 and MR2. In both cases the highest concentration used of GSK-J4 (5uM) in combination with ATRA caused significant increase of dead cells as well (LR2 - 2.1 fold, MR2 - 2.0 fold increase). Our results indicate that JMJD3 is responsible for the regulation of HOX gene expression in PML-RARa positive leukemia since changes of HOX gene expression correspond with histone modifications on the regions of HOX gene promoters. We assume that DNA methylation driven by DNMT3b can also participate in this process. Moreover, our findings demonstrate potential therapeutic implications of GSK-J4 inhibitor in combination with ATRA in patients with acute promyelocytic leukemia who are not responsive to ATRA monotherapy. Supported by P304/12/2214 and GAUK 196616 Disclosures No relevant conflicts of interest to declare.

scholarly journals Inhibition of histone methyltransferase G9a attenuates liver cancer initiation by sensitizing DNA-damaged hepatocytes to p53-induced apoptosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Takuma Nakatsuka ◽  
Keisuke Tateishi ◽  
Hiroyuki Kato ◽  
Hiroaki Fujiwara ◽  
Keisuke Yamamoto ◽  
...  
Keyword(s):  
Dna Damage ◽  
Epigenetic Modification ◽  
Histone Methyltransferase ◽  
Preventive Strategy ◽  
Tumor Initiation ◽  
Liver Transcriptome ◽  
Genetic Abnormalities ◽  
Responsive Element ◽  
Induced Apoptosis

AbstractWhile the significance of acquired genetic abnormalities in the initiation of hepatocellular carcinoma (HCC) has been established, the role of epigenetic modification remains unknown. Here we identified the pivotal role of histone methyltransferase G9a in the DNA damage-triggered initiation of HCC. Using liver-specific G9a-deficient (G9aΔHep) mice, we revealed that loss of G9a significantly attenuated liver tumor initiation caused by diethylnitrosamine (DEN). In addition, pharmacological inhibition of G9a attenuated the DEN-induced initiation of HCC. After treatment with DEN, while the induction of γH2AX and p53 were comparable in the G9aΔHep and wild-type livers, more apoptotic hepatocytes were detected in the G9aΔHep liver. Transcriptome analysis identified Bcl-G, a pro-apoptotic Bcl-2 family member, to be markedly upregulated in the G9aΔHep liver. In human cultured hepatoma cells, a G9a inhibitor, UNC0638, upregulated BCL-G expression and enhanced the apoptotic response after treatment with hydrogen peroxide or irradiation, suggesting an essential role of the G9a-Bcl-G axis in DNA damage response in hepatocytes. The proposed mechanism was that DNA damage stimuli recruited G9a to the p53-responsive element of the Bcl-G gene, resulting in the impaired enrichment of p53 to the region and the attenuation of Bcl-G expression. G9a deletion allowed the recruitment of p53 and upregulated Bcl-G expression. These results demonstrate that G9a allows DNA-damaged hepatocytes to escape p53-induced apoptosis by silencing Bcl-G, which may contribute to the tumor initiation. Therefore, G9a inhibition can be a novel preventive strategy for HCC.

scholarly journals 8a, a New Acridine Antiproliferative and Pro-Apoptotic Agent Targeting HDAC1/DNMT1

2021 ◽  
Vol 22 (11) ◽  
pp. 5516
Author(s):  
Qiting Zhang ◽  
Ziyan Wang ◽  
Xinyuan Chen ◽  
Haoxiang Qiu ◽  
Yifan Gu ◽  
...  
Keyword(s):  
Histone Deacetylase ◽  
Dna Methyltransferase ◽  
Hdac Inhibitors ◽  
Mitochondrial Pathway ◽  
Epigenetic Therapy ◽  
Protein Interaction Data ◽  
Dependent Manner ◽  
Histone Deacetylase 1 ◽  
Histiocytic Lymphoma ◽  
Dose Dependent

Epigenetic therapy using histone deacetylase (HDAC) inhibitors has become an attractive project in new drug development. However, DNA methylation and histone acetylation are important epigenetic ways to regulate the occurrence and development of leukemia. Given previous studies, N-(2-aminophenyl)benzamide acridine (8a), as a histone deacetylase 1 (HDAC1) inhibitor, induces apoptosis and shows significant anti-proliferative activity against histiocytic lymphoma U937 cells. HDAC1 plays a role in the nucleus, which we confirmed by finding that 8a entered the nucleus. Subsequently, we verified that 8a mainly passes through the endogenous (mitochondrial) pathway to induce cell apoptosis. From the protein interaction data, we found that 8a also affected the expression of DNA methyltransferase 1 (DNMT1). Therefore, an experiment was performed to assess the binding of 8a to DNMT1 at the molecular and cellular levels. We found that the binding strength of 8a to DNMT1 enhanced in a dose-dependent manner. Additionally, 8a inhibits the expression of DNMT1 mRNA and its protein. These findings suggested that the anti-proliferative and pro-apoptotic activities of 8a against leukemia cells were achieved by targeting HDAC1 and DNMT1.

scholarly journals ChIP-seq Profiling Identifies Histone Deacetylase 2 Targeting Genes Involved in Immune and Inflammatory Regulation Induced by Calcitonin Gene-Related Peptide in Microglial Cells

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xingjing Guo ◽  
Dan Chen ◽  
Shuhong An ◽  
Zhaojin Wang
Keyword(s):  
Signaling Pathway ◽  
Histone Deacetylase ◽  
Calcitonin Gene Related Peptide ◽  
Epigenetic Mechanism ◽  
Microglial Cells ◽  
Transcriptional Level ◽  
Gene Promoters ◽  
Histone Deacetylase 2 ◽  
Related Peptide ◽  
Calcitonin Gene

Calcitonin gene-related peptide (CGRP) is a mediator of microglial activation at the transcriptional level. The involvement of the epigenetic mechanism in this process is largely undefined. Histone deacetylase (HDAC)1/2 are considered important epigenetic regulators of gene expression in activated microglia. In this study, we examined the effect of CGRP on HDAC2-mediated gene transcription in microglial cells through the chromatin immunoprecipitation sequencing (ChIP-seq) method. Immunofluorescence analysis showed that mouse microglial cells (BV2) expressed CGRP receptor components. Treatment of microglia with CGRP increased HDAC2 protein expression. ChIP-seq data indicated that CGRP remarkably altered promoter enrichments of HDAC2 in microglial cells. We identified 1271 gene promoters, whose HDAC2 enrichments are significantly altered in microglia after CGRP treatment, including 1181 upregulating genes and 90 downregulating genes. Bioinformatics analyses showed that HDAC2-enriched genes were mainly associated with immune- and inflammation-related pathways, such as nitric oxide synthase (NOS) biosynthetic process, retinoic acid-inducible gene- (RIG-) like receptor signaling pathway, and nuclear factor kappa B (NF-κB) signaling pathway. The expression of these key pathways (NOS, RIG-I, and NF-κB) were further verified by Western blot. Taken together, our findings suggest that genes with differential HDAC2 enrichments induced by CGRP function in diverse cellular pathways and many are involved in immune and inflammatory responses.

scholarly journals The Flavonoid Apigenin Ameliorates Cisplatin-Induced Nephrotoxicity through Reduction of p53 Activation and Promotion of PI3K/Akt Pathway in Human Renal Proximal Tubular Epithelial Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Sung Min Ju ◽  
Jun Gue Kang ◽  
Jun Sang Bae ◽  
Hyun Ock Pae ◽  
Yeoung Su Lyu ◽  
...  
Keyword(s):  
Fruits And Vegetables ◽  
Biological Activities ◽  
Cell Types ◽  
Parp Cleavage ◽  
Akt Pathway ◽  
Induce Cell Cycle Arrest ◽  
Proximal Tubular ◽  
P53 Activation ◽  
Renal Proximal Tubular ◽  
Induced Apoptosis

Apigenin is a member of the flavone subclass of flavonoids present in fruits and vegetables. Apigenin has long been considered to have various biological activities, such as antioxidant, anti-inflammatory, and antitumorigenic properties, in various cell types. Cisplatin was known to exhibit cytotoxic effect to renal cells by inducing apoptosis through activation of p53. The present study investigated the antiapoptotic effects of apigenin on the cisplatin-treated human renal proximal tubular epithelial (HK-2) cells. HK-2 cells were pretreated with apigenin (5, 10, 20 μM) for 1 h and then treated with 40 μM cisplatin for various times. Apigenin inhibited the cisplatin-induced apoptosis of HK-2 cells. Interestingly, apigenin itself exerted cytostatic activity because of its ability to induce cell cycle arrest. Apigenin inhibited caspase-3 activity and PARP cleavage in cisplatin-treated cells. Apigenin reduced cisplatin-induced phosphorylation and expression of p53, with no significant influence on production of ROS that is known to induce p53 activation. Furthermore, apigenin promoted cisplatin-induced Akt phosphorylation, suggesting that enhanced Akt activation may be involved in cytoprotection. Taken together, these results suggest that apigenin ameliorates cisplatin-induced apoptosis through reduction of p53 activation and promotion of PI3K/Akt pathway in HK-2 cells.

Cytoplasmic acidification is not an effector mechanism of VP16 or DEX-induced apoptosis in CEM T leukaemia cells

1999 ◽  
Vol 112 (11) ◽  
pp. 1755-1760
Author(s):  
R.S. Benson ◽  
C. Dive ◽  
A.J. Watson
Keyword(s):  
Chromatin Condensation ◽  
Parp Cleavage ◽  
Intracellular Acidification ◽  
Over Expression ◽  
Effector Phase ◽  
Execution Phase ◽  
Cytoplasmic Acidification ◽  
Physiological Values ◽  
Induced Apoptosis

The role of intracellular acidification in the execution phase of apoptosis is not well understood. Here we examine the effect of Bcl-2 over-expression on intracellular acidification occurring during apoptosis. We found, that in CEM cells, neither DEX nor VP16-induced apoptosis lead to a significant change in intracellular pH (pHi). Furthermore, we found that shifting pHi away from physiological values was unable to induce chromatin condensation or poly(ADP-ribose) polymerase (PARP) cleavage in the presence of Bcl-2 over-expression. However, it was found that maximum chromatin condensation and PARP cleavage occurred at near physiological pHi values. Taken together these data suggest that intracellular acidification does not trigger the effector phase of CEM apoptosis.

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