• Title, Summary, Keyword: p53

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Effect of Adenovirus-p53 to Non-Small Cell Lung Cancer Cell Lines (Adenovirus-p53이 비소세포폐암세포 성장에 미치는 영향에 관한 연구)

  • 박종호;이춘택;김주현
    • The Korean Journal of Thoracic and Cardiovascular Surgery
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    • v.31 no.12
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    • pp.1134-1146
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    • 1998
  • Background: The tumor suppressor gene p53 is one of the most frequently altered genes in human tumors, including those of the lung. There is now a compelling evidence that wild-type p53 can negatively influence cell growth by causing G1 arrest or by inducing apoptosis. The possibilities of using p53 for gene therapy are also gathering much interest. Material and Method: Our approach towards understanding p53 function would be to study the biological consequences of overexpression of wild-type p53 in normal and tumor cells by using adenovirus vectors capable of giving high levels of the p53 gene product in cells. We have used this vector containing wild-type p53 to infect tumor cells with different p53 status (null, mutant, or wild-type) to confirm that expression of p53 in null or mutant cell lines becomes possible by Adenovirus-p53 transduction, to examine the effects of high levels of p53 expression on the growth properties of tumor cells, to evaluate the role of apoptosis in p53-mediated biological effects, and to examine the effect of Adenovirus-p53 on the tumorigenicities of the lung cancer cell lines in vitro. Result: The results of our study showed that cells expressing endogenous mutant p53 and those devoid of p53 expression altogether were significantly more sensitive to Adenovirus-p53-mediated cytotoxicity compared to tumor cells expressing endogenous wild-type p53 and that overexpression of wild-type p53 induced programmed cell death. Also we knew that Adenovirus-p53 significantly reduced tumor colony formation of human non-small cell lung cancer cell lines, and decreased the growth of pre-formed colonies in vitro. Conclusion: These results suggest that adenovirus is an efficient vector for mediating transfer and expression of tumor suppressor genes in human non-small cell lung cancer cells and that the tumor cells null for p53 or expressing mutant p53 readily undergo apoptosis by Adenovirus-p53.

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p53 Gene Mutation, Tumor p53 Protein Overexpression, and Serum Anti-p53 Antibody in Patients with Gastric Cancer (위암 환자에 있어서 p53 유전자 돌연변이, 종양 p53 단백질 과발현 및 혈청 p53 항체)

  • Bong Jin-gu;Lee Myung-Hoon;Song Kyung-Eun;Kim Taebong;Yu Wansik
    • Journal of Gastric Cancer
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    • v.3 no.4
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    • pp.206-213
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    • 2003
  • Purpose: The clinical implication of p53 mutation in gastric cancer is still unclear, as shown by the discordant results that continue to be reported in the literature. Materials and Methods: To assess p53 gene mutation, tumor p53 overexpression, and serum anti-p53 antibody, we employed a polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis, an immunohistochemistry using monoclonal antibody DO-7, and an enzymelinked immunosorbent assay (ELISA), respectively. Results: Of 169 surgical specimens of gastric cancer, mutation at exon $5\∼8$ of the p53 was identified in 33 ($19.5\%$) and was significantly correlated with lymph node metastasis. Overexpression of p53 was found in 62 specimens ($36.7\%$) and had a significant correlation with tumor differentiation. Serum anti-p53 antibody was positive in 18 patients ($10.7\%$). Twenty-three of the mutated tumors ($69.7\%$) and 39 of the non-mutated tumors ($28.7\%$) displayed immunoreactivity. Twelve of the immunopositive tumors ($19.4\%$) and 6 of the immunonegative tumors produced anti-p53 antibody. These differences were statistically significant (P<0.001 and P=0.005, respectively). There was no significant difference in survival according to the mutation of p53. Conclusion: Mutation and overexpression of p53 can be easily detected by immunohistochemistry. However, standardization of the immunohistochemical staining method, as well as guidelines for interpreting the stained result, will produce concordant results and thereby improve clinical application.

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DNA Damage-inducible Phosphorylation of p53 at Ser20 is Required for p53 Stabilization

  • Yang, Dong-Hwa;Rhee, Byung-Kirl;Yim, Tae-Hee;Lee, Hye-Jin;Kim, Jungho
    • Animal cells and systems
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    • v.6 no.3
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    • pp.263-269
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    • 2002
  • The p53 tumor suppressor gene is among the most frequently mutated and studied genes in human cancer, but the mechanisms by which it sur presses tumor formation remain unclear. DNA damage regulates both the protein levels of p53 and its affinity for specific DNA sequences. Stabilization of p53 in response to DNA damage is caused by its dissociation from Mdm2, a downstream target gene of p53 and a protein that targets p53 for degradation in the proteosome. Recent studies have suggested that phosphorylation of human p53 at Ser20 is important for stabilizing p53 in response to DNA damage through disruption of the interaction between Mdm2 and p53. We generated mice with an allele encoding changes at Ser20, known to be essential for p53 accumulation following DNA damage, to enable analyses of p53 stabilization in vivo. Our data showed that the mutant p53 was clearly defective for full stabilization of p53 in response to DNA damage. We concluded that Ser20 phosphorylation is critical for modulating the negative regulation of p53 by Mdm2, probably through phosphorylation-dependent inhibition of p53-Mdm2 interaction in the physiological context.

The Structural and Functional Role of p53 as a Cancer Therapeutic Target (암 치료 표적으로서 p53의 구조적 및 기능적 역할)

  • Han, Chang Woo;Park, So Young;Jeong, Mi Suk;Jang, Se Bok
    • Journal of Life Science
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    • v.28 no.4
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    • pp.488-495
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    • 2018
  • The p53 gene plays a critical role in the transcriptional regulation of cellular response to stress, DNA damage, hypoxia, and tumor development. Keeping in mind the recently discovered manifold physiological functions of p53, its involvement in the regulation of cancer is not surprising. In about 50% of all human cancers, inactivation of p53's protein function occurs either through mutations in the gene itself or defects in the mechanisms that activate it. This disorder plays a crucial role in tumor evolution by allowing the evasion of a p53-dependent response. Many recent studies have focused on directly targeting p53 mutants by identifying selective, small molecular compounds to deplete them or to restore their tumor-suppressive function. These small molecules should effectively regulate various interactions while maintaining good drug-like properties. Among them, the discovery of the key p53-negative regulator, MDM2, has led to the design of new small molecule inhibitors that block the interaction between p53 and MDM2. Some of these small molecule compounds have now moved from proof-of-concept studies into clinical trials, with prospects for further, more personalized anti-carcinogenic medicines. Here, we review the structural and functional consequences of wild type and mutant p53 as well as the development of therapeutic agents that directly target this gene, and compounds that inhibit the interaction between it and MDM2.

Overlapping Region of p53/Wrap53 Transcripts: Mutational Analysis and Sequence Similarity with microRNA-4732-5p

  • Pouladi, Nasser;Kouhsari, Shideh Montasser;Feizi, Mohammadali Hosseinpour;Gavgani, Reyhaneh Ravanbakhsh;Azarfam, Parvin
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.6
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    • pp.3503-3507
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    • 2013
  • Background: Although the majority of investigations concerned with TP53 and its protein have focused on coding regions, recently a set of studies highlighted significant roles of regulatory elements located in p53 mRNA, especially 5'UTR. The wrap53${\alpha}$ transcript is one of those that acts as a natural antisense agent, forming RNA-RNA hybrids with p53 mRNA and protecting it from degradation. Materials and Methods: In this study, we focused on the mutation status of exon $1{\alpha}$ of the WRAP53 gene (according to exon 1 of p53) in 160 breast tumor tissue samples and conducted a bioinformatics search for probable miRNA binding site in the p53/wrap53 overlapping region. Mutations were detected, using single stranded conformation polymorphism (SSCP) and sequencing. We applied the miRBase database for prediction of miRNAs which target overlapping region of p53/wrap53 transcripts. Results: Our results showed all samples to have wild type alleles in exon 1 of TP53 gene. We could detect a novel and unreported intronic mutation (IVS1+56, G>C) outside overlapping regions of p53/wrap53 genes in breast cancer tissues and also predict the presence of a binding site for miR-4732-5p in the 5'UTR of Wrap53 mRNA. Conclusions: From our findings we propose designing further studies focused on overexpression of miRNA-4732-5p and introducing different mutations in the overlapping region of wrap53 and p53 genes in order to study their effects on p53 and its ${\Delta}N$ isoform (${\Delta}$40p53) expression. The results may provide new pieces in the p53 targeting puzzle for cancer therapy.

Association of p53 Protein Expression with Clinical Outcome in Advanced Supralottic Cancer (진행된 성문 상부암 환자에서 p53의 발현과 임상적 의의)

  • Kang, Jing-Oh;Hong, Seong-Eong
    • Radiation Oncology Journal
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    • v.16 no.1
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    • pp.1-6
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    • 1998
  • Purpose : To determine the incidence and prognostic effect of p53 expression in patients with advanced supralottic cancer. Materials : Twenty-one cases of total 48 advanced supraglottic cancer patients who received postoperative adjuvant radiation therapy were evaluated by immunohistochemical staining employing p53 monoclonal antibody. Result : Three out of six stage III patients and four out of fifteen stage IV patients showed p53 expression without statistically significant difference (p=0.608). Five year survival rates are $93\%$ in p53 negative, $80\%$ in p53 positive patients and there was no significant difference(p=0.776). p53 expression does not show statistically significant correlation with primary tumor status(p=0.877), lymph node status(p=0.874) and age(p=0.64). Conclusion : There was no statistically significant correlation between traditionally known risk factors and p53 expression.

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Prognostic Value of p53 Overexpression in Patients with Pathologic Stage I Non-small Cell Lung Cancer (제 1기 비소세포폐암 환자에서 p53 과발현과 예후의 관계)

  • Um, Sang-Won;Kim, Hojoong;Kwon, O Jung;Han, Joungho;Shim, Young Mog
    • Tuberculosis and Respiratory Diseases
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    • v.65 no.6
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    • pp.487-494
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    • 2008
  • Background: Chromosome 17p allele losses and mutations of p53 gene are the most common genetic abnormalities in lung cancer. The purposes of this study were to evaluate the factors associated with p53 protein overexpression and to evaluate its prognostic value in patients with pathologic stage I non-small cell lung cancer (NSCLC). Methods: This is a retrospective review for the patients who underwent surgical resection at Samsung Medical Center between Jan 2003 and Jun 2004. Immunohistochemical staining for p53 protein was performed on tumor tissues from patients with lung cancer. The p53 overexpression was evaluated in relation to age, sex, smoking history, histology and pathologic stage by univariate and multivariate analyses. The disease-free survival (DFS), disease-specific survival (DSS) and overall survival (OS) were analyzed using the Kaplan-Meier methods and the differences in DFS, DSS and OS were assessed by using the log-rank tests. Results: A total of 125 patients were included in the analysis and a median frequency of p53 expression in tumor tissue was 10%. The p53 overexpression (${\geq}10%$) was more common in squamous cell carcinoma (66%) than in adenocarcinoma (38%, p=0.002). The p53 overexpression was more common in pathologic stage IB (59%) than in IA (38%, p=0.002). Patients with p53-overexpressing tumor (27 years) smoked more years compared with those without it (20 years, p=0.032). Smoking history ${\geq}25$ pack-years was more common in patients with p53 overexpression (58%) than in those without it (38%, p=0.024). In the multivariate analysis, only histology was significantly associated with p53 overexpression. However, there were no significant differences of DFS, DSS and OS in relation to p53 status. Conclusion: The p53 overexpression was associated with histology, pathologic stage and smoking history in patients with pathologic stage I NSCLC. However, the p53 overexpression was not associated with patient's survival.

Immunohistochemical study of p53 and mdm-2 in Squamous Cell Carcinoma and Leukoplakia of Head and Neck. (두경부 편평상피세포암과 백반증에서 p53과 mdm-2의 면역조직화학적 연구)

  • 김용주;정환우;황찬승;양훈식
    • Korean Journal of Bronchoesophagology
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    • v.4 no.1
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    • pp.73-78
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    • 1998
  • The mutation of p53 is the most common genetic alteration found in human cancers and has oncogenic properties. mdm-2 is a recently discoverd that controls the p53 activity by binding of its protein, so negative feedback loop has been suggested in which p53 induces mdm-2 expression. The purpose of this study was to analyze the expression of p53 in leukoplakias, mdm-2 in squamous cell carcinomas, and relationship between p53 and mdm-2 expression in leukoplakias and squamous cell carcinomas. The results were as follows : 1) The p53 was expressed 33.4% in leukoplakias 2) The mdm-2 was expressed 8.3% in leukoplakias and 22.7% in squamous cell carcinomas. 3) The expression rate of p53 was higher in specimens negative for mdm-2 than in specimens positive for mdm-2, but there was not significant relationship between p53 and mdm-2 expression. In conclusion p53 was thought to participate in early phase of oncogenesis, and mdm-2 was thought to have a role as a oncogene in squamous cell carcinoma of head and neck. Though there was not significant relationship between p53 and mdm-2 expression, mdm-2 was thought to inhibit p53 activity.

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The Significance of p53 Expression in Serum and Tissue from Patients with Lung Cancer (원발성 폐암환자의 혈청 및 조직에서의 p53단백 표현)

  • Chang, Jung-Hyun;Sung, Sun-Hee
    • Tuberculosis and Respiratory Diseases
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    • v.45 no.2
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    • pp.333-340
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    • 1998
  • Background: Lung cancer is the leading cause of cancer over the world. P53 alteration is by far the most common genetic defect in lung cancer. The mutation of p53 protein involves the loss of inhibitory function of p53 related tumor suppressor gene and resultant oncogenesis. The analysis of p53 alterations consists of immunohistochemical stain, PCR based assay, or serologic ELISA (enzyme-linked immunosorbent assay). Methods : Serum levels of p53 mutant protein were measured in 69 cases of lung cancer (adenocarcinoma n=29, epidermoid n=16, small cell n=13, large cell n=1, undifferentiated n=1, undetermined n=9) and 42 controls of respiratory disorders using ELISA. Immunohistochemical stain in tissue was performed using monoclonal antibody of p53 in lung cancer subjects. Results: Both serum p53s in nonsmall cell cancer ($0.28{\pm}0.44ng/ml$) and in small cell cancer ($0.20{\pm}0.14ng/ml$) were not different from controls ($0.34{\pm}0.20ng/ml$). Also there was no significant difference in serum p53 according to tumor stages. P53 immunohistochemical stain showed 50% positivity overall in lung cancer. There were no close correlation between serologic level and positivity of immunohistochemical stain. Conclusion: The serologic determination of p53 mutant protein is thought to have no diagnostic role in lung cancer. Immunohistochemical stain in lung cancer specimen shows 50% positivity.

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PIG3 Regulates p53 Stability by Suppressing Its MDM2-Mediated Ubiquitination

  • Jin, Min;Park, Seon-Joo;Kim, Seok Won;Kim, Hye Rim;Hyun, Jin Won;Lee, Jung-Hee
    • Biomolecules & Therapeutics
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    • v.25 no.4
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    • pp.396-403
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    • 2017
  • Under normal, non-stressed conditions, intracellular p53 is continually ubiquitinated by MDM2 and targeted for degradation. However, in response to severe genotoxic stress, p53 protein levels are markedly increased and apoptotic cell death is triggered. Inhibiting the ubiquitination of p53 under conditions where DNA damage has occurred is therefore crucial for preventing the development of cancer, because if cells with severely damaged genomes are not removed from the population, uncontrolled growth can result. However, questions remain about the cellular mechanisms underlying the regulation of p53 stability. In this study, we show that p53-inducible gene 3 (PIG3), which is a transcriptional target of p53, regulates p53 stability. Overexpression of PIG3 stabilized both endogenous and transfected wild-type p53, whereas a knockdown of PIG3 lead to a reduction in both endogenous and UV-induced p53 levels in p53-proficient human cancer cells. Using both in vivo and in vitro ubiquitination assays, we found that PIG3 suppressed both ubiquitination- and MDM2-dependent proteasomal degradation of p53. Notably, we demonstrate that PIG3 interacts directly with MDM2 and promoted MDM2 ubiquitination. Moreover, elimination of endogenous PIG3 in p53-proficient HCT116 cells decreased p53 phosphorylation in response to UV irradiation. These results suggest an important role for PIG3 in regulating intracellular p53 levels through the inhibition of p53 ubiquitination.