scholarly journals Dissection of the genetic programs of p53-mediated G1 growth arrest and apoptosis: blocking p53-induced apoptosis unmasks G1 arrest

Blood ◽  
1995 ◽  
Vol 85 (10) ◽  
pp. 2691-2698 ◽  
Author(s):  
C Guillouf ◽  
X Grana ◽  
M Selvakumaran ◽  
A De Luca ◽  
A Giordano ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Target Genes ◽  
Ectopic Expression ◽  
Growth Arrest ◽  
Genetically Engineered ◽  
Temperature Sensitive ◽  
G1 Arrest ◽  
Induced Apoptosis ◽  
High Level ◽  
And Function

Employing the myeloblastic leukemia M1 cell line, which does not express endogenous p53, and genetically engineered variants, it was recently shown that activation of p53, using a p53 temperature-sensitive mutant transgene (p53ts), resulted in rapid apoptosis that was delayed by high level ectopic expression of bcl-2. In this report, advantage has been taken of these M1 variants to investigate the relationship between p53-mediated G1 arrest and apoptosis. Flow cytometric cell cycle analysis has provided evidence that activation of wild-type (wt) p53 function in M1 cells resulted in the induction of G1 growth arrest; this was clearly seen in the M1p53/bcl-2 cells because of the delay in apoptosis that unmasked p53-induced G1 growth arrest. This finding was further corroborated at the molecular level by analysis of the expression and function of key cell cycle regulatory genes in M1p53 versus M1p53/bcl-2 cells after the activation of wt p53 function; events that take place at early times during the p53-induced G1 arrest occur in both the M1p53 and the M1p53/bcl-2 cells, whereas later events occur only in the M1p53/bcl-2 cells, which undergo delayed apoptosis, thereby allowing the cells to complete G1 arrest. Finally, it was observed that a spectrum of p53 target genes implicated in p53-induced growth suppression and apoptosis were similarly regulated, either induced (gadd45, waf1, mdm2, and bax) or suppressed (c-myc and bcl-2), after activation of wt p53 function in M1p53 and M1p53/bcl-2 cells. Taken together, these findings show that wt p53 can simultaneously induce the genetic programs of both G1 growth arrest and apoptosis within the same cell type, in which the genetic program of cell death can proceed in either G1-arrested (M1p53/bcl-2) or cycling (M1p53) cells. These findings increase our understanding of the functions of p53 as a tumor suppressor and how alterations in these functions could contribute to malignancy.

scholarly journals Cancer cells activate p53 in response to 10-formyltetrahydrofolate dehydrogenase expression

2005 ◽  
Vol 391 (3) ◽  
pp. 503-511 ◽  
Author(s):  
Natalia V. Oleinik ◽  
Natalia I. Krupenko ◽  
David G. Priest ◽  
Sergey A. Krupenko
Keyword(s):  
Cancer Cells ◽  
Ectopic Expression ◽  
A549 Cells ◽  
Dominant Negative ◽  
G1 Arrest ◽  
Transactivation Domain ◽  
Downstream Target ◽  
Formyltetrahydrofolate Dehydrogenase ◽  
Induced Apoptosis ◽  
Hct116 Cells

A folate enzyme, FDH (10-formyltetrahydrofolate dehydrogenase; EC 1.5.1.6), is not a typical tumour suppressor, but it has two basic characteristics of one, i.e. it is down-regulated in tumours and its expression is selectively cytotoxic to cancer cells. We have recently shown that ectopic expression of FDH in A549 lung cancer cells induces G1 arrest and apoptosis that was accompanied by elevation of p53 and its downstream target, p21. It was not known, however, whether FDH-induced apoptosis is p53-dependent or not. In the present study, we report that FDH-induced suppressor effects are strictly p53-dependent in A549 cells. Both knockdown of p53 using an RNAi (RNA interference) approach and disabling of p53 function by dominant-negative inhibition with R175H mutant p53 prevented FDH-induced cytotoxicity in these cells. Ablation of the FDH-suppressor effect is associated with an inability to activate apoptosis in the absence of functional p53. We have also shown that FDH elevation results in p53 phosphorylation at Ser-6 and Ser-20 in the p53 transactivation domain, and Ser-392 in the C-terminal domain, but only Ser-6 is strictly required to mediate FDH effects. Also, translocation of p53 to the nuclei and expression of the pro-apoptotic protein PUMA (Bcl2 binding component 3) was observed after induction of FDH expression. Elevation of FDH in p53 functional HCT116 cells induced strong growth inhibition, while growth of p53-deficient HCT116 cells was unaffected. This implies that activation of p53-dependent pathways is a general downstream mechanism in response to induction of FDH expression in p53 functional cancer cells.

scholarly journals G1 arrest and differentiation can occur independently of Rb family function

2010 ◽  
Vol 191 (4) ◽  
pp. 809-825 ◽  
Author(s):  
Stacey E. Wirt ◽  
Adam S. Adler ◽  
Véronique Gebala ◽  
James M. Weimann ◽  
Bethany E. Schaffer ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Mammalian Cells ◽  
Regulatory Networks ◽  
Target Genes ◽  
Family Members ◽  
Mouse Embryos ◽  
G1 Arrest ◽  
Cell Cycle Exit ◽  
Family Function ◽  
Rb Pathway

The ability of progenitor cells to exit the cell cycle is essential for proper embryonic development and homeostasis, but the mechanisms governing cell cycle exit are still not fully understood. Here, we tested the requirement for the retinoblastoma (Rb) protein and its family members p107 and p130 in G0/G1 arrest and differentiation in mammalian cells. We found that Rb family triple knockout (TKO) mouse embryos survive until days 9–11 of gestation. Strikingly, some TKO cells, including in epithelial and neural lineages, are able to exit the cell cycle in G0/G1 and differentiate in teratomas and in culture. This ability of TKO cells to arrest in G0/G1 is associated with the repression of key E2F target genes. Thus, G1 arrest is not always dependent on Rb family members, which illustrates the robustness of cell cycle regulatory networks during differentiation and allows for the identification of candidate pathways to inhibit the expansion of cancer cells with mutations in the Rb pathway.

scholarly journals Growth Suppression by Acute PromyelocyticLeukemia-Associated Protein PLZF Is Mediated by Repression ofc-mycExpression

2003 ◽  
Vol 23 (24) ◽  
pp. 9375-9388 ◽  
Author(s):  
Melanie J. McConnell ◽  
Nathalie Chevallier ◽  
Windy Berkofsky-Fessler ◽  
Jena M. Giltnane ◽  
Rupal B. Malani ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Cell Cycle Arrest ◽  
Target Genes ◽  
Ectopic Expression ◽  
Growth Suppression ◽  
Quiescent State ◽  
Cycle Arrest

ABSTRACT The transcriptional repressor PLZF was identified by its translocation with retinoic acid receptor alpha in t(11;17) acute promyelocytic leukemia (APL). Ectopic expression of PLZF leads to cell cycle arrest and growth suppression, while disruption of normal PLZF function is implicated in the development of APL. To clarify the function of PLZF in cell growth and survival, we used an inducible PLZF cell line in a microarray analysis to identify the target genes repressed by PLZF. One prominent gene identified was c-myc. The array analysis demonstrated that repression of c-myc by PLZF led to a reduction in c-myc-activated transcripts and an increase in c-myc-repressed transcripts. Regulation of c-myc by PLZF was shown to be both direct and reversible. An interaction between PLZF and the c-myc promoter could be detected both in vitro and in vivo. PLZF repressed the wild-type c-myc promoter in a reporter assay, dependent on the integrity of the binding site identified in vitro. PLZF binding in vivo was coincident with a decrease in RNA polymerase occupation of the c-myc promoter, indicating that repression occurred via a reduction in the initiation of transcription. Finally, expression of c-myc reversed the cell cycle arrest induced by PLZF. These data suggest that PLZF expression maintains a cell in a quiescent state by repressing c-myc expression and preventing cell cycle progression. Loss of this repression through the translocation that occurs in t(11;17) would have serious consequences for cell growth control.

Ectopic expression of p27Kip1 in oligodendrocyte progenitor cells results in cell-cycle growth arrest

1998 ◽  
Vol 36 (3) ◽  
pp. 431-440 ◽  
Author(s):  
Ravi Tikoo ◽  
Donna J. Osterhout ◽  
Patrizia Casaccia-Bonnefil ◽  
Prem Seth ◽  
Andrew Koff ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Progenitor Cells ◽  
Ectopic Expression ◽  
Growth Arrest ◽  
Oligodendrocyte Progenitor Cells ◽  
Oligodendrocyte Progenitor ◽  
Cycle Growth

scholarly journals Silica Nanoparticles Sensitize Human Multiple Myeloma Cells to Snake (Walterinnesia aegyptia) Venom-Induced Apoptosis and Growth Arrest

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Douaa Sayed ◽  
Mohamed K. Al-Sadoon ◽  
Gamal Badr
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Silica Nanoparticles ◽  
Biological Effects ◽  
Growth Arrest ◽  
Hematopoietic Stem ◽  
Human Multiple Myeloma ◽  
Induced Apoptosis ◽  
The Impact ◽  
Effective Treatments

Background. Multiple myeloma (MM), an almost incurable disease, is the second most common blood cancer. Initial chemotherapeutic treatment could be successful; however, resistance development urges the use of higher toxic doses accompanied by hematopoietic stem cell transplantation. The establishment of more effective treatments that can overcome or circumvent chemoresistance has become a priority. We recently demonstrated that venom extracted fromWalterinnesia aegyptia(WEV) either alone or in combination with silica nanoparticles (WEV+NPs) mediated the growth arrest and apoptosis of prostate cancer cells. In the present study, we evaluated the impact of WEV alone and WEV+NP on proliferation and apoptosis of MM cells.Methods. The impacts of WEV alone and WEV+NP were monitored in MM cells from 70 diagnosed patients. The influences of WEV and WEV+NP were assessed with flow cytometry analysis.Results. WEV alone and WEV+NP decreased the viability of MM cells. Using a CFSE proliferation assay, we found that WEV+NP strongly inhibited MM cell proliferation. Furthermore, analysis of the cell cycle using the propidium iodide (PI) staining method indicated that WEV+NP strongly altered the cell cycle of MM cells and enhanced the induction of apoptosis.Conclusions. Our data reveal the biological effects of WEV and WEV+NP on MM cells that enable these compounds to function as effective treatments for MM.

scholarly journals A novel anti-proliferative role of HMGA2 in induction of apoptosis through caspase 2 in primary human fibroblast cells

2015 ◽  
Vol 35 (1) ◽  
Author(s):  
Xi Shi ◽  
Baoqing Tian ◽  
Wenlong Ma ◽  
Na Zhang ◽  
Yuehua Qiao ◽  
...  
Keyword(s):  
Caspase 3 ◽  
Flow Cytometric Analysis ◽  
Ectopic Expression ◽  
High Mobility ◽  
Primary Human Fibroblast ◽  
Primary Cell Lines ◽  
Induction Of Apoptosis ◽  
Caspase 2 ◽  
Induced Apoptosis ◽  
High Level

The HMGA2 (high-mobility group AT-hook) protein has previously been shown as an oncoprotein, whereas ectopic expression of HMGA2 is found to induce growth arrest in primary cells. The precise mechanisms underlying this phenomenon remain to be unravelled. In the present study, we determined that HMGA2 was able to induce apoptosis in WI38 primary human cells. We show that WI38 cells expressing high level of HMGA2 were arrested at G2/M phase and exhibited apoptotic nuclear phenotypes. Meanwhile, the cleaved caspase 3 (cysteine aspartic acid-specific protease 3) was detected 8 days after HMGA2 overexpression. Flow cytometric analysis confirmed that the ratio of cells undergoing apoptosis increased dramatically. Concurrently, other major apoptotic markers were also detected, including the up-regulation of p53, Bax and cleaved caspase 9, down-regulation of Bcl-2; as well as release of cytochrome c from the mitochondria. We further demonstrate that the shRNA (small-hairpin RNA)-mediated Apaf1 (apoptotic protease activating factor 1) silencing partially rescued the HMGA2-induced apoptosis, which was accompanied by the decrease of cleaved caspase-3 level and a decline of cell death ratio. Our results also reveal that γH2A was accumulated in nuclei during the HMGA2-induced apoptosis along with the up-regulation of cleaved caspase 2, suggesting that the HMGA2-induced apoptosis was dependent on the pathway of DNA damage. Overall, the present study unravelled a novel function of HMGA2 in induction of apoptosis in human primary cell lines, and provided clues for clarification of the mechanistic action of HMGA2 in addition to its function as an oncoprotein.

scholarly journals Inhibition of p53-mediated growth arrest by overexpression of cyclin-dependent kinases.

1996 ◽  
Vol 16 (8) ◽  
pp. 4445-4455 ◽  
Author(s):  
K M Latham ◽  
S W Eastman ◽  
A Wong ◽  
P W Hinds
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Growth Arrest ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Aberrant Expression ◽  
Cycle Progression ◽  
Cyclin Dependent Kinases ◽  
Rat Fibroblasts ◽  
Wild Type P53

Rat fibroblasts transformed by a temperature-sensitive mutant of murine p53 undergo a reversible growth arrest in G1 at 32.5 degrees C, the temperature at which p53 adopts a wild-type conformation. The arrested cells contain inactive cyclin-dependent kinase 2 (cdk2) despite the presence of high levels of cyclin E and cdk-activating kinase activity. This is due in part to p53-dependent expression of the p2l cdk inhibitor. Upon shift to 39 degrees C, wild-type p53 is lost and cdk2 activation and pRb phosphorylation occur concomitantly with loss of p2l. This p53-mediated growth arrest can be abrogated by overexpression of cdk4 and cdk6 but not cdk2 or cyclins, leading to continuous proliferation of transfected cells in the presence of wild-type p53 and p2l. Kinase-inactive counterparts of cdk4 and cdk6 also rescue these cells from growth arrest, implicating a noncatalytic role for cdk4 and cdk6 in this resistance to p53-mediated growth arrest. Aberrant expression of these cell cycle kinases may thus result in an oncogenic interference with inhibitors of cell cycle progression.

scholarly journals Temperature-Sensitive Lethal Pseudorevertants of ste Mutations in Saccharomyces cerevisiae

Genetics ◽  
1987 ◽  
Vol 115 (4) ◽  
pp. 627-636
Author(s):  
Margaret E Katz ◽  
Jill Ferguson ◽  
Steven I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Complementation Group ◽  
Temperature Sensitive ◽  
G1 Arrest ◽  
Pheromone Response ◽  
Cycle Arrest ◽  
Homogeneous Cell ◽  
Complementation Groups ◽  
Mutant Cells

ABSTRACT A procedure was devised to isolate mutations that could restore conjugational competence to temperature sensitive ste mutants and simultaneously confer temperature-sensitive lethal growth phenotypes. Three such mutations, falling into two complementation groups, were identified on the basis of suppression of ste5 alleles. These same mutations were later shown to be capable of suppressing ste4 and ste7 alleles. Five mutations in a single complementation group were isolated as suppressors of ste2 alleles. None of the mutations described in this study conferred a homogeneous cell cycle arrest phenotype, and all were shown to define complementation groups distinct from those previously identified in studies of cell division cycle (cdc) mutations. In no instance did pseudoreversion appear to be achieved by mutational G1 arrest of ste mutant cells. Instead, it is proposed that the mutations restore conjugation by reestablishing the normal pheromone response.

PPARr agonist, troglitazone induce growth arrest and apoptosis in MDA-MB-231 human breast cancer cell

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 13155-13155
Author(s):  
J. Park ◽  
Y. Lee ◽  
H. Yu ◽  
M. Han ◽  
B. Kim ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
Human Breast Cancer ◽  
Kinase Inhibitors ◽  
Growth Arrest ◽  
Ppar Gamma ◽  
G1 Arrest ◽  
Human Breast ◽  
Ppar Γ ◽  
Cycle Dependent

13155 Background: Estrogen receptor (ER)-negative breast carcinomas do not respond to hormone therapy, making their effective treatment very difficult. It is recently reported that peroxisome proliferator-activated receptor-gamma (PPAR-γ) has become a potential target for the prevention and treatment of human cancer. Therefore, PPAR-γ agonist, troglitazone has been extensively studied as a chemopreventive or therapeutic agent in several types of cancer. The purpose of this study was to assess whether troglitazone (TRO) would induce cell growth arrest and apoptosis in MDA-MB-231 (ER-negative) human breast cancer cells. Methods: Cytostatic/cytotoxic effects of troglitazone were measured with MTT assay. The cell cycle distribution was evaluated with flow cytometer. The expression of cyclin-dependent kinase inhibitors, p21, p27, and cell cycle dependent kinases was measured with Western blotting. Apoptotic cells were determined by Hoechst staining and TUNEL assay. Results: Troglitazone inhibited cell proliferation by inducing 65% G0/G1 arrest after 48 h. Accumulation of cells in G0/G1 was accompanied by a decrease of Rb protein phosphorylation associated with reduced activities of cell cycle dependent kinases (CDKs) such as cdk2 and cyclin D. Troglitazone increased the expression cyclin kinase inhibitors, p21 and p27 as MDA-MB-231 cell underwent G0/G1 arrest. Apoptotic effect by troglitazone demonstrated that apoptotic cells elevated from 2.5-fold of the control level at 10 uM, to 3.6-fold at 50 uM and to 4.7-fold at 75 uM. Conclusion: These results indicate that activation of PPAR-gamma with troglitazone induces apoptosis through cell cycle inhibition in estrogen receptor-negative breast cancer cell MDA-MB-231. PPAR-gamma therefore represents a putative molecular target for chemopreventive therapy or inhibition of breast cancer growth. No significant financial relationships to disclose.

The Cdk inhibitors p25rum1 and p40SIC1 are functional homologues that play similar roles in the regulation of the cell cycle in fission and budding yeast

1998 ◽  
Vol 111 (6) ◽  
pp. 843-851 ◽  
Author(s):  
A. Sanchez-Diaz ◽  
I. Gonzalez ◽  
M. Arellano ◽  
S. Moreno
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
G1 Phase ◽  
G1 Arrest ◽  
Cdk Inhibitors ◽  
A Cell ◽  
High Level ◽  
Cell Cycle Block ◽  
Cdc28 Kinase ◽  
P34 Cdc2

p25rum1 and p40SIC1 are specific inhibitors of p34(cdc2/CDC28) kinase complexes with B-type cyclins that play a central role in the regulation of the G1 phase of the cell cycle. We show here that low levels of expression of SIC1 in Schizosaccharomyces pombe rescues all the phenotypes of cells lacking the rum1+ gene. In addition, high level expression of SIC1 in S. pombe induces extra rounds of DNA replication without mitosis, a phenotype very similar to the overexpression of rum1+. Transient expression of rum1+ in S. cerevisiae restores the G1 arrest phenotype of cdc4 sic1Delta double mutants. Overproduction of rum1+ in Saccharomyces cerevisiae causes a cell cycle block in G1 with a phenotype similar to inactivation of all the Clb cyclins. Finally, we have mapped the cyclin interacting domain and Cdk inhibitory domain to a region of about 80 amino acids in p25rum1 that has significant homology to the C-terminal domain of p40SIC1. All these observations suggest that fission yeast p25rum1 and budding yeast p40SIC1 define a family of Cdk inhibitors that specifically down regulate cyclin B/Cdk1 during the G1 phase of the cell cycle.

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