scholarly journals p16Ink4a Interferes with Abelson Virus Transformation by Enhancing Apoptosis

2004 ◽  
Vol 78 (7) ◽  
pp. 3304-3311 ◽  
Author(s):  
Zohar Sachs ◽  
Norman E. Sharpless ◽  
Ronald A. DePinho ◽  
Naomi Rosenberg
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Cell Cycle Progression ◽  
Cell Transformation ◽  
Regulatory Protein ◽  
Cycle Progression ◽  
Multistep Process ◽  
Second Tumor ◽  
Abelson Virus ◽  
Primary Transformants

ABSTRACT Pre-B-cell transformation by Abelson virus (Ab-MLV) is a multistep process in which primary transformants are stimulated to proliferate but subsequently undergo crisis, a period of erratic growth marked by high levels of apoptosis. Inactivation of the p53 tumor suppressor pathway is an important step in this process and can be accomplished by mutation of p53 or down-modulation of p19Arf, a p53 regulatory protein. Consistent with these data, pre-B cells from either p53 or Ink4a/Arf null mice bypass crisis. However, the Ink4a/Arf locus encodes both p19Arf and a second tumor suppressor, p16Ink4a, that blocks cell cycle progression by inhibiting Cdk4/6. To determine if p16Ink4a plays a role in Ab-MLV transformation, primary transformants derived from Arf −/− and p16 Ink4a−/− mice were compared. A fraction of those derived from Arf −/− animals underwent crisis, and even though all p16 Ink4a−/− primary transformants experienced crisis, these cells became established more readily than cells derived from +/+ mice. Analyses of Ink4a/Arf −/− cells infected with a virus that expresses both v-Abl and p16Ink4a revealed that p16Ink4a expression does not alter cell cycle profiles but does increase the level of apoptosis in primary transformants. These results indicate that both products of the Ink4a/Arf locus influence Ab-MLV transformation and reveal that in addition to its well-recognized effects on the cell cycle, p16Ink4a can suppress transformation by inducing apoptosis.

scholarly journals The RASSF6 Tumor Suppressor Protein Regulates Apoptosis and Cell Cycle Progression via Retinoblastoma Protein

2018 ◽  
Vol 38 (17) ◽  
Author(s):  
Shakhawoat Hossain ◽  
Hiroaki Iwasa ◽  
Aradhan Sarkar ◽  
Junichi Maruyama ◽  
Kyoko Arimoto-Matsuzaki ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Cell Cycle Arrest ◽  
Cell Cycle Progression ◽  
Target Genes ◽  
Loss Of Function ◽  
Cycle Progression ◽  
P53 Expression ◽  
Cycle Arrest ◽  
Hct116 Cells

ABSTRACT RASSF6 is a member of the tumor suppressor Ras association domain family (RASSF) proteins. RASSF6 is frequently suppressed in human cancers, and its low expression level is associated with poor prognosis. RASSF6 regulates cell cycle arrest and apoptosis and plays a tumor suppressor role. Mechanistically, RASSF6 blocks MDM2-mediated p53 degradation and enhances p53 expression. However, RASSF6 also induces cell cycle arrest and apoptosis in a p53-negative background, which implies that the tumor suppressor function of RASSF6 does not depend solely on p53. In this study, we revealed that RASSF6 mediates cell cycle arrest and apoptosis via pRb. RASSF6 enhances the interaction between pRb and protein phosphatase. RASSF6 also enhances P16INK4A and P14ARF expression by suppressing BMI1. In this way, RASSF6 increases unphosphorylated pRb and augments the interaction between pRb and E2F1. Moreover, RASSF6 induces TP73 target genes via pRb and E2F1 in a p53-negative background. Finally, we confirmed that RASSF6 depletion induces polyploid cells in p53-negative HCT116 cells. In conclusion, RASSF6 behaves as a tumor suppressor in cancers with loss of function of p53, and pRb is implicated in this function of RASSF6.

scholarly journals The homeoprotein DLX3 and tumor suppressor p53 co-regulate cell cycle progression and squamous tumor growth

Oncogene ◽  
2015 ◽  
Vol 35 (24) ◽  
pp. 3114-3124 ◽  
Author(s):  
E Palazzo ◽  
M Kellett ◽  
C Cataisson ◽  
A Gormley ◽  
P W Bible ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Tumor Growth ◽  
Cell Cycle Progression ◽  
Tumor Suppressor P53 ◽  
Cycle Progression ◽  
Regulate Cell Cycle Progression

scholarly journals Regulation of CDK7–Carboxyl-Terminal Domain Kinase Activity by the Tumor Suppressor p16INK4A Contributes to Cell Cycle Regulation

2000 ◽  
Vol 20 (20) ◽  
pp. 7726-7734 ◽  
Author(s):  
Eiji Nishiwaki ◽  
Saralinda L. Turner ◽  
Susanna Harju ◽  
Shiro Miyazaki ◽  
Masahide Kashiwagi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Rna Polymerase Ii ◽  
Cell Cycle Progression ◽  
Kinase Activity ◽  
Alternative Pathway ◽  
Cycle Progression ◽  
Terminal Domain ◽  
Carboxyl Terminal Domain ◽  
Carboxyl Terminal

ABSTRACT The eukaryotic cell cycle is regulated by cyclin-dependent kinases (CDKs). CDK4 and CDK6, which are activated by D-type cyclins during the G1 phase of the cell cycle, are thought to be responsible for phosphorylation of the retinoblastoma gene product (pRb). The tumor suppressor p16INK4A inhibits phosphorylation of pRb by CDK4 and CDK6 and can thereby block cell cycle progression at the G1/S boundary. Phosphorylation of the carboxyl-terminal domain (CTD) of the large subunit of RNA polymerase II by general transcription factor TFIIH is believed to be an important regulatory event in transcription. TFIIH contains a CDK7 kinase subunit and phosphorylates the CTD. We have previously shown that p16INK4A inhibits phosphorylation of the CTD by TFIIH. Here we report that the ability of p16INK4A to inhibit CDK7-CTD kinase contributes to the capacity to induce cell cycle arrest. These results suggest that p16INK4A may regulate cell cycle progression by inhibiting not only CDK4-pRb kinase activity but also by modulating CDK7-CTD kinase activity. Regulation of CDK7-CTD kinase activity by p16INK4A thus may represent an alternative pathway for controlling cell cycle progression.

scholarly journals VP16 targets an amino-terminal domain of HCF involved in cell cycle progression.

1997 ◽  
Vol 17 (10) ◽  
pp. 6139-6146 ◽  
Author(s):  
A C Wilson ◽  
R N Freiman ◽  
H Goto ◽  
T Nishimoto ◽  
W Herr
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Cycle Progression ◽  
Regulatory Protein ◽  
Proteolytic Processing ◽  
Early Gene ◽  
Temperature Sensitive ◽  
Interaction Domain ◽  
Cycle Progression ◽  
Amino Terminal

The herpes simplex virus (HSV) regulatory protein VP16 activates HSV immediate-early gene transcription through formation of a multiprotein-DNA complex on viral promoters that includes the preexisting nuclear proteins HCF and Oct-1. The HCF protein is a complex of amino- and carboxy-terminal polypeptides derived from a large (approximately 2,000-amino-acid) precursor by proteolytic processing. Here we show that a 361-residue amino-terminal region of HCF is sufficient to bind VP16, stabilize VP16-induced complex assembly with Oct-1 and DNA, and activate transcription in vivo. This VP16 interaction region contains six kelch-like repeats, a degenerate repeat motif that is likely to fold as a distinctive beta-propeller structure. The third HCF kelch repeat includes a proline residue (P134) that is mutated to serine in hamster tsBN67 cells, resulting in a temperature-sensitive defect in cell proliferation. This missense mutation also prevents direct association between HCF and VP16, suggesting that VP16 mimics a cellular factor required for cell proliferation. Rescue of the tsBN67 cell proliferation defect by HCF, however, requires both the VP16 interaction domain and an adjacent basic region, indicating that HCF utilizes multiple regions to promote cell cycle progression.

scholarly journals The RASSF6 tumor suppressor protein regulates apoptosis and the cell cycle progression via Retinoblastoma protein

2018 ◽  
Author(s):  
Shakhawoat Hossain ◽  
Hiroaki Iwasa ◽  
Aradhan Sarkar ◽  
Junichi Maruyama ◽  
Kyoko Arimoto-Matsuzaki ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Cell Cycle Arrest ◽  
Cell Cycle Progression ◽  
Target Genes ◽  
Loss Of Function ◽  
Cycle Progression ◽  
P53 Expression ◽  
Cycle Arrest ◽  
Hct116 Cells

ABSTRACTRASSF6 is a member of the tumor suppressor Ras-association domain family (RASSF) proteins. RASSF6 is frequently suppressed in human cancers and its low expression is associated with poor prognosis. RASSF6 regulates cell cycle arrest and apoptosis and plays a tumor suppressor role. Mechanistically, RASSF6 blocks MDM2-mediated p53 degradation and enhances p53 expression. However, RASSF6 also induces cell cycle arrest and apoptosis in the p53-negative background, which implies that the tumor suppressor function of RASSF6 does not depend solely on p53. In this study, we have revealed that RASSF6 mediates cell cycle arrest and apoptosis via pRb. RASSF6 enhances the interaction between pRb and protein phosphatase. RASSF6 also enhances P16INK4A and P14ARF expression through suppressing BMI1. In this way, RASSF6 increases unphosphorylated pRb and augments the interaction between pRb and E2F1. Moreover, RASSF6 induces TP73-target genes via pRb and E2F1 in the p53-negative background. Finally, we confirmed that RASSF6 depletion induces polypoid cells in p53-negative HCT116 cells. In conclusion, RASSF6 behaves as a tumor suppressor in cancers with the loss-of-function of p53, and pRb is implicated in this function of RASSF6.

scholarly journals Restoration of miR-193a-5p and miR-146 a-5p Expression Induces G1 Arrest in Colorectal Cancer through Targeting of MDM2/p53

2019 ◽  
Vol 10 (1) ◽  
pp. 130-134 ◽  
Author(s):  
Saeed Noorolyai ◽  
Elham Baghbani ◽  
Leili Aghebati Maleki ◽  
Amir Baghbanzadeh Kojabad ◽  
Dariush Shanehbansdi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Colorectal Cancer ◽  
Cell Cycle ◽  
Tumor Suppressor ◽  
Cell Cycle Progression ◽  
Cyclin B ◽  
G1 Arrest ◽  
Cycle Progression ◽  
Ht 29

Purpose: Colorectal cancer (CRC) remains a universal and lethal cancer owing to metastatic and relapsing disease. Currently, the role of microRNAs has been checked in tumorigeneses. Numerous studies have revealed that between the tumor suppressor miRNAs, the reduced expression of miR-146a-5p and -193a-5p in several cancers including CRC tissues are related with tumor progression and poor prognosis of patients. The purpose of this study is to examine the role of miR-146 a-5p and -193 a-5p in CRC cell cycle progression. Methods: The miR-193a-5p and -146 a-5p mimics were transfected into HT-29 CRC cells via jetPEI transfection reagent and their impact was assessed on p53, cyclin B, and NF-kB gene expression. The inhibitory effect of these miRNAs on cell cycle was assessed by flow cytometry. The consequence of miR-193a-5p and miR-146 a-5p on the protein expression level of Murine double minute 2 (MDM2) was assessed by western blotting. Results: miR193a-5p and -146a-5p regulated the expression of MDM2 protein and p53, cyclin B, and NF-kB gene expression in CRC cells. Treatment of HT-29 cells with miRNA-146a-5p and -193a-5p induced G1 cell cycle arrest. Conclusion: The findings of our study suggest that miR146a-5p and -193a-5p may act as a potential tumor suppressor by their influence on cell cycle progression in CRC cells. Thus, miRNA-146a-5p and -193a-5p restoration may be recommended as a potential therapeutic goal in the treatment of CRC patients.

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