FOXO1 mediates hypoxia-induced G0/G1 arrest in ovarian somatic granulosa cells by activating the TP53INP1-p53-CDKN1A pathway.

The development of ovarian follicles constitutes the foundation of female reproduction. The proliferation of granulosa cells (GCs) is a basic process required to ensure normal follicular development. However, the mechanisms involved in controlling GC cell cycle are not fully understood. Here, by performing gene expression profiling in the domestic pig (Sus scrofa), we showed that cell cycle arrest at G0/G1 phase is highly correlated with pathways associated with hypoxic stress and FOXO signalling. Specifically, the elevated proportion of GCs at the arrested G0/G1 phase was accompanied by increased nuclear translocation of FOXO1 under conditions of hypoxia both in vivo and in vitro. Furthermore, phosphorylation of 14-3-3 by the JNK kinase is required for hypoxia-mediated FOXO1 activation and the resultant G0/G1 arrest. Notably, a FOXO1 mutant without DNA-binding activity failed to induce G0/G1 arrest of GCs during hypoxia. Importantly, we identified a new target gene of FOXO1, namely TP53INP1, which contributes to suppression of the G1-S cell cycle transition in response to hypoxia. Furthermore, we demonstrated that the inhibitory effect of the FOXO1-TP53INP1 axis on the GC cell cycle is mediated through a p53-CDKN1A-dependent mechanism. These findings could provide avenues for the clinical treatment of human infertility caused by impaired follicular development.

The involvement of calcium in the toxic effect of 4-methylethcathinone on SH-SY5Y cells.

Neurotoxicity induced by psychoactive substances is often accompanied by an imbalance of intracellular calcium ions. It is unclear whether calcium ions play a role in the toxicity induced by psychoactive substances. In the present study, we aimed to evaluate the occurrence of calcium dysregulation and its contribution to cytotoxicity in human neurotypic SH-SY5Y cells challenged with a recently developed psychoactive substance 4-methylethcathinone (4-MEC). An increase in the intracellular calcium was detected by inductively coupled plasma atomic emission spectrometry and Fluo-3 AM dye in SH-SY5Y cells after being treated with 4-MEC. The increase of intracellular Ca2+ level mediated G0/G1 cell cycle arrest and ROS/endoplasmic reticulum stress-autophagy signaling pathways to achieve the toxicity of 4-MEC. In particular, N-acetyl-L-cysteine, a classical antioxidant, was found to be a potential treatment for 4-MEC-induced toxicity. Taken together, our results demonstrate that an increase in intracellular calcium content is one of the mechanisms of 4-MEC-induced toxicity. This study provides a molecular basis for the toxicity mechanism and therapeutic intervention of psychoactive substances.

N-Propargylic ß-enaminones in breast cancer cells: Cytotoxicity, apoptosis, and cell cycle analyses.

Breast cancer is one of the most common cancers worldwide and the discovery of new cytotoxic agents is needed. Enaminones are regarded to be a significant structural motif that is found in a variety of pharmacologically active compounds however the number of studies investigating the anticancer activities of N-propargylic ß-enaminones (NPEs) is limited. Herein we investigated the potential cytotoxic and apoptotic effects of 23 different NPEs (1-23) on human breast cancer cells. Cytotoxicity was evaluated via MTT assay. Apoptotic cell death and cell cycle distributions were investigated by flow cytometry. CM-H2DCFDA dye was used to evaluate cellular ROS levels. Expression levels of Bcl-2, Bax, p21, and Cyclin D1 were measured by quantitative real-time PCR. ADME properties were calculated using the ADMET 2.0 tool. NPEs 4, 9, 16, and 21 showed selective cytotoxic activity against breast cancer cells with SI values >2. NPEs induced apoptosis and caused significant changes in Bcl-2 and Bax mRNA levels. The cell cycle was arrested at the G0/G1 phase and levels of p21 and Cyclin D1 were upregulated in both breast cancer cells. ROS levels were significantly increased by NPEs, suggesting that the cytotoxic and apoptotic effects of NPEs were mediated by ROS. ADME analysis revealed that NPEs showed favorable distributions in both breast cancer cell lines, meaning good lipophilicity values, low unfractionated values, and high bioavailability. Therefore, these potential anticancer compounds should be further validated by in vivo studies for their appropriate function in human health with a safety profile, and a comprehensive drug interaction study should be performed.

The Anti-G0 Manifesto: Should a problematic construct (G0) with no biological reality be removed from the cell cycle? Yes!

It is widely accepted that there exists a "resting" or "quiescent" state where a growing cell leaves the cell cycle to enter what is often called the "G0-phase." I propose that there is no biological reality to the "G0-phase." The experimental basis for proposing a G0-phase is re-examined and re-analyzed here showing that the G0-phase is an anthropomorphic construct with no biological reality.

Targeting Akt/NF-κB/p53 Pathway and Apoptosis Inducing Potential of 1,2-Benzenedicarboxylic Acid, Bis (2-Methyl Propyl) Ester Isolated from Onosma bracteata Wall. against Human Osteosarcoma (MG-63) Cells.

Onosma bracteata Wall. is an important medicinal and immunity-enhancing herbs. This plant is commonly used in the preparation of traditional Ayurvedic drugs to treat numerous diseases. Inspired by the medicinal properties of this plant, the present study aimed to investigate the antiproliferative potential and the primary molecular mechanisms of the apoptotic induction against human osteosarcoma (MG-63) cells. Among all the fractions isolated from O. bracteata, ethyl acetate fraction (Obea) showed good antioxidant activity in superoxide radical scavenging assay and lipid peroxidation assay with an EC50 value of 95.12 and 80.67 µg/mL, respectively. Silica gel column chromatography of ethyl acetate (Obea) fraction of O. bracteata yielded a pure compound, which was characterized by NMR, FTIR, and HR-MS analysis and was identified as 1,2-benzene dicarboxylic acid, bis (2-methyl propyl) ester (BDCe fraction). BDCe fraction was evaluated for the antiproliferative potential against human osteosarcoma MG-63, human neuroblastoma IMR-32, and human lung carcinoma A549 cell lines by MTT assay and exhibited GI50 values of 37.53 µM, 56.05 µM, and 47.12 µM, respectively. In MG-63 cells, the BDCe fraction increased the level of ROS and simultaneously decreased the mitochondria membrane potential (MMP) potential by arresting cells at the G0/G1 phase, suggesting the initiation of apoptosis. Western blotting analysis revealed the upregulation of p53, caspase3, and caspase9 while the expressions of p-NF-κB, p-Akt and Bcl-xl were decreased. RT-qPCR studies also showed upregulation in the expression of p53 and caspase3 and downregulation in the expression of CDK2, Bcl-2 and Cyclin E genes. Molecular docking analysis displayed the interaction between BDCe fraction with p53 (-151.13 kcal/mol) and CDK1 (-133.96 kcal/mol). The results of the present work suggest that the BDCe fraction has chemopreventive properties against osteosarcoma (MG-63) cells through the induction of cell cycle arrest and apoptosis via Akt/NF-κB/p53 pathways. This study contributes to the understanding of the utilization of BDCe fraction in osteosarcoma treatment.

Mangiferin, a naturally occurring polyphenol, mitigates oxidative stress induced premature senescence in human dermal fibroblast cells.

Chronic oxidative stress has been associated with several human ailments including the condition of aging. Extensive studies have shown the causal relationship between oxidative stress, aging, and cellular senescence. In this regard, forestalling or preventing senescence could delay the aging process as well as act as an intervention against premature aging. Hence, in the present study, we investigated the anti-senescence potential of Mangiferin (MGN) against Hydrogen peroxide (H2O2) induced premature senescence using human dermal fibroblast cells. Early passage human dermal fibroblasts cells were exposed to H2O2 (10 µM) for 15 days. In order to assess the anti-senescence property of MGN, cells were preconditioned with MGN (10 µM / 50 µM; 2 h) followed by addition of H2O2 (10 µM). H2O2 mediated induction of premature senescence was accompanied by elevated ROS, lowering of mitochondrial mass and membrane potential, changes in ATP content along with G0/G1 arrest and SA-ß-gal expression. While, conditioning the cells with MGN lowered oxidative burden, stabilized mitochondrial membrane potential / mass and protected the cells against cell cycle arrest, ultimately rendering protection against premature senescence. The present findings showed that MGN might act as a potential cytoprotective nutraceutical that can prolong the onset of chronic oxidative stress mediated premature senescence.

Copper exposure induces hepatic G0/G1 cell-cycle arrest through suppressing the Ras/PI3K/Akt signaling pathway in mice.

Copper (Cu), as a common chemical contaminant in environment, is known to be toxic at high concentrations. The current research demonstrates the effects of copper upon hepatocyte cell-cycle progression (CCP) in mice. Institute of cancer research (ICR) mice (n = 240) at an age of four weeks were divided randomly into groups treated with different doses of Cu (0, 4, 8, and 16 mg/kg) for 21 and 42 days. Results showed that high Cu exposure caused hepatocellular G0/G1 cell-cycle arrest (CCA) and reduced cell proportion in the G2/M phase. G0/G1 CCA occurred with down-regulation (p < 0.05) of Ras, p-PI3K (Tyr458), p-Akt (Thr308), p-forkhead box O3 (FOXO3A) (Ser253), p-glycogen synthase kinase 3-ß (GSK3-ß) (Ser9), murine double minute 2 (MDM2) protein, and mRNA expression levels, and up-regulation (p < 0.05) of PTEN, p-p53 (Ser15), p27, p21 protein, and mRNA expression levels, which subsequently suppressed (p < 0.05) the protein and mRNA expression levels of CDK2/4 and cyclin E/D. These results indicate that Cu exposure suppresses the Ras/PI3K/Akt signaling pathway to reduce the level of CDK2/4 and cyclin E/D, which are essential for the G1-S transition, and finally causes hepatocytes G0/G1 CCA.

In vitro cytotoxicity, cellular uptake, reactive oxygen species and cell cycle arrest studies of novel ruthenium(II) polypyridyl complexes towards A549 lung cancer cell line.

Ruthenium(II) polypyridyl complexes have displayed some promising biological responses against a variety of cancers and have emerged as a potential candidate that can show significant antitumor activity. Three ruthenium(II) polypyridyl complexes were biologically evaluated in vitro against the A549 cancer cell line. The complexes were selected based on initial DNA intercalation studies and MTT viability screening and were selected based on the most promising candidates, the [Ru(bpy)2o-CPIP].2PF6 (complex 1), [Ru(phen)2o-CPIP].2PF6 (complex 2) and [Ru(biq)2o-CPIP].2PF6 (complex 3). Confocal cellular uptake studies confirmed the intracellular transport of complexes into A549. Cytoplasmic and the nucleic accumulation of the complex 1 and 2 was seen while no fluorescent microscopy was performed for complex 3 due to instrumental limitations. Cellular cytotoxicity was investigated with the aid of the Alamar blue assay. The complexes displayed concentration and time dependent inhibitory effects yielding IC50 values from 5.00 to 32.75 µM. Complex 1 exhibit highest cytotoxicity with IC50 value of 5.00 ± 1.24 µM. All of the complexes have shown a significant effect in the reduction of intracellular reactive oxygen species (ROS) levels. Finally, the complexes have shown a transient effect on the cell cycle by arresting it at G0/G1 phase except for complex 2 [Ru(phen)2o-CPIP].2PF6 which has shown the significant G0/G1 arrest.

Physiological modulation of endogenous BRCA1 p220 abundance suppresses DNA damage during the cell cycle.

Endogenous BRCA1 p220 expression peaks in S and G2 when it is activated, and the protein participates in certain key DNA damage responses. In contrast, its expression is markedly reduced in G0/G1. While variations in transcription represent a significant part of p220 expression control, there is at least one other relevant process. We found that a microRNA, miR-545, that is expressed throughout the cell cycle down-modulates endogenous p220 mRNA and protein abundance directly in both G0/G1 and S/G2. When miR-545 function was inhibited by a specific antagomir, endogenous p220 expression increased in G0/G1, and aberrant p220-associated DNA damage responses and de novo DNA strand breaks accumulated. Analogous results were observed upon inhibition of miR-545 function in S/G2. Both sets of antagomir effects were mimicked by infecting cells with a p220 cDNA-encoding adenoviral vector. Thus, strand breaks were a product of p220 overexpression, and their prevention by miR-545 depends on its modulation of p220 expression. Breaks were also dependent on aberrant, overexpressed p220-driven recruitment of RAD51 to either spontaneously arising or mutagen-based DNA damage sites. Hence, when its level is not physiologically maintained, endogenous p220 aberrantly directs at least one DNA repair protein, RAD51, to damage sites, where their action contributes to the development of de novo DNA damage. Thus, like its loss, a surfeit of endogenous p220 function represents a threat to genome integrity.

Potential Antitumor Effects of 6-Gingerol in p53-Dependent Mitochondrial Apoptosis and Inhibition of Tumor Sphere Formation in Breast Cancer Cells.

Hormone-specific anticancer drugs for breast cancer treatment can cause serious side effects. Thus, treatment with natural compounds has been considered a better approach as this minimizes side effects and has multiple targets. 6-Gingerol is an active polyphenol in ginger with various modalities, including anticancer activity, although its mechanism of action remains unknown. Increases in the level of reactive oxygen species (ROS) can lead to DNA damage and the induction of DNA damage response (DDR) mechanism, leading to cell cycle arrest apoptosis and tumorsphere suppression. Epidermal growth factor receptor (EGFR) promotes tumor growth by stimulating signaling of downstream targets that in turn activates tumor protein 53 (p53) to promote apoptosis. Here we assessed the effect of 6-gingerol treatment on MDA-MB-231 and MCF-7 breast cancer cell lines. 6-Gingerol induced cellular and mitochondrial ROS that elevated DDR through ataxia-telangiectasia mutated and p53 activation. 6-Gingerol also induced G0/G1 cell cycle arrest and mitochondrial apoptosis by mediating the BAX/BCL-2 ratio and release of cytochrome c. It also exhibited a suppression ability of tumorsphere formation in breast cancer cells. EGFR/Src/STAT3 signaling was also determined to be responsible for p53 activation and that 6-gingerol induced p53-dependent intrinsic apoptosis in breast cancer cells. Therefore, 6-gingerol may be used as a candidate drug against hormone-dependent breast cancer cells.

Anticancer Potential of Damnacanthal and Nordamnacanthal from Morinda elliptica Roots on T-lymphoblastic Leukemia Cells.

BACKGROUND: This study reports on the cytotoxic properties of nordamnacanthal and damnacanthal, isolated from roots of Morinda elliptica on T-lymphoblastic leukaemia (CEM-SS) cell lines. METHODS: MTT assay, DNA fragmentation, ELISA and cell cycle analysis were carried out. RESULTS: Nordamnacanthal and damnacanthal at IC50 values of 1.7 µg/mL and10 µg/mL, respectively. At the molecular level, these compounds caused internucleosomal DNA cleavage producing multiple 180-200 bp fragments that are visible as a "ladder" on the agarose gel. This was due to the activation of the Mg2+/Ca2+-dependent endonuclease. The induction of apoptosis by nordamnacanthal was different from the one induced by damnacanthal, in a way that it occurs independently of ongoing transcription process. Nevertheless, in both cases, the process of dephosphorylation of protein phosphates 1 and 2A, the ongoing protein synthesis and the elevations of the cytosolic Ca2+ concentration were not needed for apoptosis to take place. Nordamnacanthal was found to have a cytotoxic effect by inducing apoptosis, while damnacanthal caused arrest at the G0/G1 phase of the cell cycle. CONCLUSION: Damnacanthal and nordamnacanthal have anticancer properties, and could act as potential treatment for T-lymphoblastic leukemia.

Styryl-cinnamate hybrid inhibits glioma by alleviating translation, bioenergetics and other key cellular responses leading to apoptosis.

Gliomas are lethal and aggressive form of brain tumors with resistance to conventional radiation and cytotoxic chemotherapies; inviting continuous efforts for drug discovery and drug delivery. Interestingly, small molecule hybrids are one such pharmacophore that continues to capture interest owing to their pluripotent medicinal effects. Accordingly, we earlier reported synthesis of potent Styryl-cinnamate hybrids (analogues of Salvianolic acid F) along with its plausible mode of action (MOA). We explored iTRAQ-LC/MS-MS technique to deduce differentially expressed landscape of native & phospho-proteins in treated glioma cells. Based on this, Protein-Protein Interactome (PPI) was looked into by employing computational tools and further validated in vitro. We hereby report that the Styryl-cinnamate hybrid, an analogue of natural Salvianolic acid F, alters key regulatory proteins involved in translation, cytoskeleton development, bioenergetics, DNA repair, angiogenesis and ubiquitination. Cell cycle analysis dictates arrest at G0/G1 stage along with reduced levels of cyclin D; involved in G1 progression. We discovered that Styryl-cinnamate hybrid targets glioma by intrinsically triggering metabolite-mediated stress. Various oncological circuits alleviated by the potential drug candidate strongly supports the role of such pharmacophores as anticancer drugs. Although, further analysis of SC hybrid in treating xenografts or solid tumors is yet to be explored but their candidature has gained huge impetus through this study. This study equips us better in understanding the shift in proteomic landscape after treating glioma cells with SC hybrid. It also allows us to elicit molecular targets of this potential drug before progressing to preclinical studies.

MicroRNA-519d-3p inhibits cell proliferation and cell cycle G1/S transition in glioma by targeting CCND1.

Glioma is the most common highly malignant primary brain tumor. MicroRNA-519d-3p exerts important effects in several tumors, but its functional role in glioma remained poorly understood. In this study, we found miR-519d-3p expression was significantly decreased in glioma tissues and cell lines. Moreover, the in vitro experiments showed that overexpression of miR-519d-3p suppressed cell proliferation and induced cell cycle G0/G1 phase arrest using MTT and flow cytometry assays in glioma cell lines, U87 and U251. Mechanistically, Cyclin D1 (CCND1) was predicted and confirmed as the direct target genes of miR-519d-3p using luciferase report assay. In addition, knockdown of CCND1 imitated the suppressive effects of miR-519d-3p on cell proliferation and cell cycle progression. Furthermore, restoration of CCND1 reversed the effects of miR-519d-3p overexpression in glioma cells. Taken together, these data demonstrate that suppression of CCND1 by miR-519d-3p might be a therapeutic target for glioma.Abbreviations miR-519d-3p: microRNA-519d-3p; CCND1: Cyclin D1; ATCC: American Type Culture Collection; MTT: 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide; PI: propidium iodide; WT: wild type; MUT: mutant type; SD: standard deviation.

Design, Synthesis and Biological Evaluation of Jahanyne Analogs as Cell Cycle Arrest Inducers.

Jahanyne, a lipopeptide with a unique terminal alkynyl and OEP (2-(1-oxo-ethyl)-pyrrolidine) moiety, exhibits anticancer activity. We synthesized jahanyne and analogs modified at the OEP moiety, employing an α-fluoromethyl ketone (FMK) strategy. Preliminary bioassays indicated that compound 1b (FMK-jahanyne) exhibited decreased activities to varying degrees against most of the cancer cells tested, whereas the introduction of a fluorine atom to the α-position of a hydroxyl group (2b) enhanced activities against all lung cancer cells. Moreover, jahanyne and 2b could induce G0/G1 cell cycle arrest in a concentration-dependent manner.

The Gene and Protein Expression of the Main Components of the Lipolytic System in Human Myocardium and Heart Perivascular Adipose Tissue. Effect of Coronary Atherosclerosis.

The aim of our study was to examine the regulation of triacylglycerols (TG) metabolism in myocardium and heart perivascular adipose tissue in coronary atherosclerosis. Adipose triglyceride lipase (ATGL) is the major TG-hydrolase. The enzyme is activated by a protein called comparative gene identification 58 (CGI-58) and inhibited by a protein called G0/G1 switch protein 2 (G0S2). Samples of the right atrial appendage and perivascular adipose tissue were obtained from two groups of patients: 1-with multivessel coronary artery disease qualified for coronary artery bypass grafting (CAD), 2-patients with no atherosclerosis qualified for a valve replacement (NCAD). The mRNA and protein analysis of ATGL, HSL, CGI-58, G0S2, FABP4, FAT/CD36, LPL, ß-HAD, CS, COX4/1, FAS, SREBP-1c, GPAT1, COX-2, 15-LO, and NFκß were determined by using real-time PCR and Western Blot. The level of lipids (i.e., TG, diacylglycerol (DG), and FFA) was examined by GLC. We demonstrated that in myocardium coronary atherosclerosis increases only the transcript level of G0S2 and FABP4. Most importantly, ATGL, ß-HAD, and COX4/1 protein expression was reduced and it was accompanied by over double the elevation in TG content in the CAD group. The fatty acid synthesis and their cellular uptake were stable in the myocardium of patients with CAD. Additionally, the expression of proteins contributing to inflammation was increased in the myocardium of patients with coronary stenosis. Finally, in the perivascular adipose tissue, the mRNA of G0S2 was elevated, whereas the protein content of FABP-4 was increased and for COX4/1 diminished. These data suggest that a reduction in ATGL protein expression leads to myocardial steatosis in patients with CAD.

Isolation and Cytotoxic Activity of Phyllocladanes from the Roots of Acacia schaffneri (Leguminosae).

In research on natural molecules with cytotoxic activity that can be used for the development of new anticancer agents, the cytotoxic activity of hexane, chloroform, and methanol extracts from the roots of Acacia schaffneri against colon, lung, and skin cancer cell lines was explored. The hexane extract showed the best activity with an average IC50 of 10.6 µg mL-1. From this extract, three diterpenoids, phyllocladan-16α,19-diol (1), phyllocladan-16α-ol (2), and phylloclad-16-en-3-ol (3), were isolated and characterized by their physical and spectroscopic properties. Diterpenoids 1 and 2 were tested against the same cancer cell lines, as well as their healthy counterparts, CCD841 CoN, MRC5, and VH10, respectively. Compound 1 showed moderate activity (IC50 values between 24 and 70 µg mL-1), although it showed a selective effect against cancer cell lines. Compound 2 was practically inactive. The cytotoxicity mechanism of 1 was analyzed by cell cycle, indicating that the compound induces G0/G1 cell cycle arrest. This effect might be generated by DNA alkylation damage. In addition, compound 1 decreased migration of HT29 cells.

Repressing of NHERF1 inhibits liver cancer progression by promoting the production of ROS.

NHERF1/EBP50 is a PDZ-scaffold protein initially identified as an organizer and modulator of transporters and channels at the apical side of epithelia via actin-binding ezrin-moesin-radixin proteins. Presently, hepatocellular carcinoma (HCC) is one of the most deadly cancers in the world and has no effective therapeutic strategies. In the present study, we attempted to explore the role of NHERF1 in regulating liver cancer progression. The results indicated that NHERF1 was significantly expressed in liver tumor samples compared to the corresponding adjacent normal tissues. HCC patients with low NHERF1 exhibited better survival rate. Additionally, repressing NHERF1 expression markedly down-regulated the cell proliferation. G0/G1 transition was highly induced by NHERF1 knockdown, accompanied with reduced expressions of Cyclin D1 and cyclin-dependent kinase 4 (CDK4), as well as the enhanced expression of p27, phosphatase and tensin homolog (PTEN) and p53. Moreover, NHERF1 suppression significantly induced apoptosis in liver cancer cells by promoting the activation of Caspase-3 and poly (ADP-ribose) polymerase (PARP). We also observed a remarkable increase of reactive oxygen species (ROS) production in NHERF1-knockdown cells, along with c-Jun-N-terminal kinase (JNK) phosphorylation. Importantly, suppressing ROS production abolished NHERF1 knockdown-induced JNK activation. Moreover, cell cycle-regulatory proteins meditated by NHERF1 knockdown in liver cancer cells were abrogated by the pre-treatment of ROS scavenger. Further, restraining ROS generation also diminished NHERF1 knockdown-induced apoptosis. In vivo, we also found that NHERF1 knockdown markedly reduced the tumor growth. In conclusion, the results suggested that NHERF1 played an essential role in regulating liver cancer progression, and repressing NHERF1 expression exhibited significant anticancer effects via the induction of G0/G1 phase arrest, apoptosis and ROS generation.

ATPR-induced differentiation and G0/G1 phase arrest in acute promyelocytic leukemia by repressing EBP50/NCF1 complex to promote the production of ROS.

Our previous study has demonstrated that 4-amino-2-trifluoromethyl-phenyl Retinate (ATPR) can induce human leukemia NB4 cells differentiation and G0/G1 phase arrest, but the underlying mechanism is still unclear. In this study, we used proteomics to screen differentially expressed protein profiles in NB4 cells before and after ATPR treatment in vitro. We analyzed the peptides digested from total cellular proteins by reverse phase LC-MS/MS and then performed label-free quantitative analysis. We found 27 significantly up-regulated proteins in the ATPR group compared to the control group. NCF1 was the most significantly changed protein. Immunoprecipitation and double immunofluorescent staining showed that EBP50 bind to NCF1. We further explored the potential molecular mechanism of EBP50/NCF1 complex in ATPR-induced differentiation and G0/G1 phase arrest. The results showed that ATPR remarkably reduced the expression of EBP50 in vivo and in vitro. Interestingly, the reduction of EBP50 contributed to ROS release by modulating the subcellular localization of NCF1. The reduction of EBP50 also contributed to G0/G1 phase arrest by inhibiting CyclinD1, CyclinA2 and CDK4, as well as promoting the differentiation of NB4 cells by increasing the expression of CD11b. Furthermore, we found that the overexpression of EBP50 restrained the effects of ATPR on differentiation and G0/G1 phase arrest in NB4 cells. These results suggest that ATPR-induced differentiation and G0/G1 phase arrest in acute promyelocytic leukemia (APL) by repressing EBP50/NCF1 complex to promote the production of ROS, and the results from in vivo experiments were consistent with those from in vitro studies. Therefore, our finding results suggest that EBP50 may be a new target for ATPR in the treatment of APL.

Changes in the position and volume of inactive X chromosomes during the G0/G1 transition.

In female mammals, each cell silences one X chromosome by converting it into transcriptionally inert heterochromatin. The inactivation is concomitant with epigenetic changes including methylation of specific histone residues and incorporation of macroH2A. Such epigenetic changes may exert influence on the positioning of the inactive X chromosome (Xi) within the nucleus beyond the level of chromatin structure. However, the dynamic positioning of the inactive X chromosome during cell cycle remains unclear. Here, we show that H3K27me3 is a cell-cycle-independent marker for the inactivated X chromosomes in WI38 cells. By utilizing this marker, three types of Xi locations in the nuclei are classified, which are envelope position (associated with envelope), mid-position (between the envelope and nucleolus), and nucleolus position (associated with the nucleolus). Moreover, serial-section analysis revealed that the inactive X chromosomes in the mid-position appear to be sparser and less condensed than those associated with the nuclear envelope or nucleolus. During the transition from G0 to G1 phase, the inactive X chromosomes tend to move from the envelope position to the nucleolus position in WI38 cells. Our results imply a role of chromosome positioning in maintaining the organization of the inactive X chromosomes in different cell phases.

Butylene fipronil induces apoptosis in PC12 murine nervous cells via activation of p16-CDK4/6-cyclin D1 and mitochondrial apoptotic pathway.

Butylene fipronil (BFPN) is a phenylpyrazole insecticide, acting at the γ-aminobutyric acid (GABA) receptor. Here, we show that BFPN inducedcytotoxicity in PC12 murinenervous cells, which lacks GABA receptor. Treatment with BFPN for 48 hours significantly enhanced G0/G1 arrest and induced apoptosis. BFPN decreased the expression of cyclin-dependent kinase (CDK4 and CDK6) and increased P16 and cyclin D1. Simultaneously, Bcl-2 protein was declined while Bax and cytochrome c were significantly enhanced in BFPN-treated groups. The apoptotic enzymes caspase-8, -9, and -3 were also activated by BFPN. Furthermore, treatment with BFPN significantly stimulated reactive oxygen species (ROS) generation, and pretreatment with antioxidant diphenyleneiodonium, substantially reduced cell death. Overall, these results suggest that BFPN is effective to induce G0/G1-phase arrest and apoptosis in PC12 murine nervous cell. Stimulating ROS generation and activation of P16-CDK4/6-cyclin D1 and mitochondrial apoptotic pathway may participate in the cytotoxicity of BFPN.