scholarly journals Role ofp16INK4Ain Replicative Senescence and DNA Damage-Induced Premature Senescence in p53-Deficient Human Cells

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Razmik Mirzayans ◽  
Bonnie Andrais ◽  
Gavin Hansen ◽  
David Murray
Keyword(s):  
Dna Damage ◽  
Ionizing Radiation ◽  
Replicative Senescence ◽  
Human Cancer ◽  
Human Cells ◽  
Premature Senescence ◽  
Wild Type ◽  
Regulatory Relationship ◽  
Human Cancer Cell Lines ◽  
Wild Type P53

Thep16INK4A(hereafter p16) tumor suppressor is encoded by theINK4A/ARFlocus which is among the most commonly dysregulated sequences in human cancer. By inhibiting cyclin-dependent kinases, p16 activates the G1-S checkpoint, and this response is often considered to be critical for establishing a senescence-like growth arrest. Not all studies support a universal role for p16 in senescence. Single-cell analysis of noncancerous human fibroblast cultures undergoing senescence as a function of culture age (replicative senescence) has revealed that p16 is not expressed in the majority (>90%) of cells that exhibit features of senescence (e.g., flattened and enlarged morphology coupled with senescence-associatedβ-galactosidase expression), ruling out a requirement for p16 in this process. In addition, ionizing radiation triggers premature senescence in human cancer cell lines that do not express p16. These observations are made with cells that express wild-type p53, a key mediator of the DNA damage response. In this paper, we examine the growing evidence suggesting a negative regulatory relationship between p16 and p53 and discuss recent reports that implicate a role for p16 in replicative senescence and ionizing radiation-induced premature senescence in human cells that lack wild-type p53 function.

Role of P53 Mutations in the Radiosensitivity Status of Tumor Cells

1998 ◽  
Vol 84 (5) ◽  
pp. 517-520 ◽  
Author(s):  
Vincenzo Chiarugi ◽  
Lucia Magnelli ◽  
Marina Cinelli
Keyword(s):  
Dna Damage ◽  
Cellular Response ◽  
P53 Protein ◽  
Cell Cycle Control ◽  
P53 Mutations ◽  
Wild Type ◽  
Bladder Tumors ◽  
Variable Effect ◽  
Wild Type P53

Wild-type p53 is involved in cellular response to DNA damage including cell cycle control, DNA repair and activation of apoptosis. Accumulation of p53 protein following DNA damage may initiate the apoptotic process, resulting in cell death. DNA damage induced by radiation is an example of apoptotic stimulus involving p53. Regulation of apoptosis by p53 can occur through transcriptional regulation of pro-apoptotic (e.g. bax) and anti-apoptotic (e.g. bel-2) factors. Although wild-type p53 usually sensitizes cells to radiation therapy, p53 mutations have a variable effect on radiation response. For example p53 mutations in bone or breast tumors have been found to be associated with resistance to chemotherapeutic drugs or ionizing radiation. Mutated p53 has has been reported to increase sensitivity to radiation and drugs in colorectal and bladder tumors. The present brief commentary tries to find an explanation at molecular level of these conflicting results.

Enhanced DNA binding capacity on up‐regulated epidermal wild‐type p53 in vitiligo by H 2 O 2 ‐mediated oxidation: a possible repair mechanism for DNA damage

2009 ◽  
Vol 23 (11) ◽  
pp. 3790-3807 ◽  
Author(s):  
Mohamed M. A. E. L. Salem ◽  
Mohammad Shalbaf ◽  
Nicholas C. J. Gibbons ◽  
Bhaven Chavan ◽  
J. M. Thornton ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Binding ◽  
Binding Capacity ◽  
Wild Type ◽  
Repair Mechanism ◽  
Wild Type P53 ◽  
Mediated Oxidation

scholarly journals 11 Study of Polynucleotide Kinase/Phosphatase (PNKP) Mutations Found in a Patient with Microcephaly, Seizures, and Developmental Delay (MCSZ) and Glioblastoma

2018 ◽  
Vol 45 (S3) ◽  
pp. S2-S2
Author(s):  
Bingcheng Jiang ◽  
Chibawanye I. Ene ◽  
Bonnie Cole ◽  
Jeff Ojemann ◽  
Sarah Leary ◽  
...  
Keyword(s):  
Human Cancer ◽  
Neurodevelopmental Disorder ◽  
Site Directed Mutagenesis ◽  
Expression Vectors ◽  
Wild Type ◽  
Double Mutation ◽  
Mutant Proteins ◽  
Human Cancer Cell Lines ◽  
Mammalian Expression ◽  
Polynucleotide Kinase

The enzyme polynucleotide kinase/phosphatase (PNKP) plays a key role in DNA repair by resolving the chemistry at DNA strand breaks. Mutations in PNKP (chromosome 19q13.4) are known to cause MCSZ, a serious neurodevelopmental disorder, but to date there has been no link to cancer initiation or progression. However, a child with MCSZ recently presented at Seattle Children's Hospital with a 3-cm glioblastoma. The child was shown to have two germline mutations in PNKP. To study the effects of the PNKP mutations found in this patient, we generated mutant PNKP cDNAs carrying either the individual mutations or the double mutation using site directed mutagenesis. These cDNAs were incorporated into bacterial and mammalian expression vectors. The bacterially expressed mutant proteins as well as the wild type have been purified and are undergoing testing for PNKP DNA kinase and phosphatase activity. The PNKP cDNAs, fused to GFP, were expressed in Hela and HCT116 human cancer cell lines. High-content analysis and micro-irradiation techniques are being used to determine PNKP localization within the cells and recruitment to damaged DNA. Our preliminary results indicate that the mutations alter the ratio of nuclear to cytoplasmic PNKP compared to the wild-type protein.

scholarly journals Down-regulation of Wild-type p53-induced Phosphatase 1 (Wip1) Plays a Critical Role in Regulating Several p53-dependent Functions in Premature Senescent Tumor Cells

2013 ◽  
Vol 288 (23) ◽  
pp. 16212-16224 ◽  
Author(s):  
Elvira Crescenzi ◽  
Zelinda Raia ◽  
Francesco Pacifico ◽  
Stefano Mellone ◽  
Fortunato Moscato ◽  
...  
Keyword(s):  
Dna Damage ◽  
Tumor Cells ◽  
Dna Damage Response ◽  
Critical Role ◽  
Wild Type ◽  
Down Regulation ◽  
Senescent Phenotype ◽  
Response To Chemotherapy ◽  
Damage Response ◽  
Wild Type P53

Premature or drug-induced senescence is a major cellular response to chemotherapy in solid tumors. The senescent phenotype develops slowly and is associated with chronic DNA damage response. We found that expression of wild-type p53-induced phosphatase 1 (Wip1) is markedly down-regulated during persistent DNA damage and after drug release during the acquisition of the senescent phenotype in carcinoma cells. We demonstrate that down-regulation of Wip1 is required for maintenance of permanent G2 arrest. In fact, we show that forced expression of Wip1 in premature senescent tumor cells induces inappropriate re-initiation of mitosis, uncontrolled polyploid progression, and cell death by mitotic failure. Most of the effects of Wip1 may be attributed to its ability to dephosphorylate p53 at Ser15 and to inhibit DNA damage response. However, we also uncover a regulatory pathway whereby suppression of p53 Ser15 phosphorylation is associated with enhanced phosphorylation at Ser46, increased p53 protein levels, and induction of Noxa expression. On the whole, our data indicate that down-regulation of Wip1 expression during premature senescence plays a pivotal role in regulating several p53-dependent aspects of the senescent phenotype.

Bcl-2 Protects against p53-Induced Apoptosis through Hdm2

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5333-5333
Author(s):  
Line Wergeland ◽  
Kevin B. Spurgers ◽  
Eystein Oveland ◽  
Torill Høiby ◽  
Manel Cascallo ◽  
...  
Keyword(s):  
Dna Damage ◽  
Acute Myeloid Leukemia ◽  
Protein Level ◽  
Myeloid Leukemia ◽  
Proteasome Inhibitors ◽  
Wild Type ◽  
Inhibitory Molecule ◽  
Wild Type P53 ◽  
Induced Apoptosis ◽  
Acute Myeloid

Abstract Hdm2 is up-regulated in several malignancies including sarcomas and acute myeloid leukemia, where it counteracts the anti-proliferative and pro-apoptotic effect of wild type p53. The anti-apoptotic protein Bcl-2 is often elevated in many tumors with wild type p53 and serves to block p53-induced apoptosis. We demonstrate that the protein level of Hdm2 positively correlates with the level of Bcl-2 and follows the Bcl-2 level in different cell systems. Over-expression of Bcl-2 protects Hdm2 from DNA-damage induced degradation in a dose dependant manner. In addition, modulation of Bcl-2 by shRNA knockdown reduced the Hdm2 protein level in parallel. Consequently, treatment of AML cells with the Bcl-2 small inhibitory molecule HA14-1 attenuated the level of Hdm2. The Bcl-2 level, but not the DNA damage induced Hdm2 degradation, was affected by disruption of the E3 ubiquitin ligase activity of Hdm2. In addition, the DNA-damage induced Hdm2 down-regulation was blocked by disrupted E1 ubiquitin-activation, defect polyubiquitination and by proteasome inhibitors. Finally, we show that Bcl-2 protection from p53-induced cell death requires co-expression of Hdm2 in double null p53/mdm2 mouse embryonic fibroblasts. Our results indicate that Bcl-2 regulates the Hdm2 level and that Hdm2 is a key mediator in Bcl-2 inhibition of p53-induced apoptosis. This is of particular therapeutic interest for cancers displaying elevated Hdm2 and Bcl-2, like sarcoma and acute myeloid leukemia.

Targeting MHC-linked wild type p53 with TCR mimic single chain diabody for cancer immunotherapy.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. 2524-2524
Author(s):  
Suman Paul ◽  
Jacqueline Douglass ◽  
Annika Schaefer ◽  
Emily Han-Chung Hsiue ◽  
Alexander Pearlman ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Surface ◽  
Cancer Immunotherapy ◽  
Cell Killing ◽  
Human Cells ◽  
Wild Type ◽  
Single Chain ◽  
Nsg Mice ◽  
Wild Type P53

2524 Background: Increased tumor suppressor protein p53 expression is observed in a wide range of human cancers. As a result there is intense interest in targeting p53 for cancer therapy. Intracellular p53 is inaccessible to therapeutic antibodies that bind cell surface proteins. However, intracellular proteins including p53 are degraded into peptides that are presented on cell surface in association with HLA class I molecules. Thus p53 peptide-HLA (p53-HLA) complexes can be antibody targets. Methods: Using phage display we identified a novel anti-p53-HLA single chain variable fragment (scFv) clone-43 that recognizes a wild-type p53 10-mer epitope bound to HLA-A*2402. By coupling our clone-43 scFv with an anti-CD3 scFv, we generated a single chain diabody (scDb) designed to activate T-cells against p53-expressing target cells. Results: In-vitro co-culture of clone-43 scDb with donor human T-cells and p53 expressing SIG-M5 cancer cells results in SIG-M5 cell killing and concomitant T-cell interferon gamma (IFNγ) release. In contrast, similar co-culture with SIG-M5 p53-knock out (KO) cells showed no cell killing and minimal IFNγ release demonstrating specificity of clone-43 to p53 expressing cells. Additionally, in-vivo growth of p53 expressing SW480 cancer cell xenografts in NSG mice was completely terminated by clone-43 scDb injections. A major concern for wild-type p53 epitope targeting is potential on-target off-tumor effect on non-cancerous tissue. We observed significant in-vitro clone-43 scDb mediated killing of human HLA-A*24:02 peripheral blood mononuclear cells. To better evaluate effect of clone-43 scDb on non-neoplastic human cells, we engrafted HLA-A*24:02 human CD34+ hematopoietic stem cells into NSG mice to generate a humanized mouse model with circulating mature human CD45+ cells. Clone-43 scDb treatment resulted in selective depletion of circulating human cells while the same cells persisted in mice treated with unrelated control scDb. Conclusions: Our observation that immune targeting of wild-type p53 epitope results in significant off-tumor hematopoietic cell death is contrary to previously published reports and carries important implications for future anti-p53 antibody and vaccine design for cancer immunotherapy.

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