• The Korean Journal of Physiology and Pharmacology
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• v.21 no.2
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• pp.267-273
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• 2017

The p53-inducible gene 3 (PIG3), initially identified as a gene downstream of p53, plays an important role in the apoptotic process triggered by p53-mediated reactive oxygen species (ROS) production. Recently, several studies have suggested that PIG3 may play a role in various types of cancer. However, the functional significance of PIG3 in cancer remains unclear. Here, we found that PIG3 was highly expressed in human colon cancer cell lines compared to normal colon-derived fibroblasts. Therefore, we attempted to elucidate the functional role of PIG3 in colon cancer. PIG3 overexpression increases the colony formation, migration and invasion ability of HCT116 colon cancer cells. Conversely, these tumorigenic abilities were significantly decreased in in vitro studies with PIG3 knockdown HCT116 cells. PIG3 knockdown also attenuated the growth of mouse xenograft tumors. These results demonstrate that PIG3 is associated with the tumorigenic potential of cancer cells, both in vitro and in vivo, and could play a key oncogenic role in colon cancer.

• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.460-465
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• 2003

Structural alteration of p53 and overexpression of p53 protein are the most common genetic abnormalities in various kinds of human cancer. Mutations in the p53 tumor-suppressor gene are usually associated with an advanced development of colorectal cancer characterized by the transition from the adenoma to carcinoma stage. Mutations in exons 5-8 of the p53 gene were analyzed by the polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP) and denaturing high performance liquid chromatography(DHPLC). SSCP analysis detected 7 mutations(C13109>T) in 50 colorectal cancer samples(14%) at exon 5, and DHPLC analysis detected 7 mutations (C13109>T) and 2 mutation(C13202>A, C13204>G) in 50 colorectal cancer samples(18%) at exon 5. All of 9 mutations were proved by sequencing analysis. We conclude that DHPLC is a highly sensitive and specific method for p53 gene mutations.

• 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.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.2
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• pp.511-516
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• 2012

Background: We investigated the association between polymorphisms in the $p53$ tumor suppressor gene and breast cancer risk in women especially in the Southern part of India. Methods: Genotyping was performed for 50 breast cancer women and 50 controls to determine the status of $p53$ exon 4 codon 72 polymorphism and exon 7 codon 249 mutation and their possible role in breast cancer risk. Results: Frequency of Arg/Arg at codon 72 was 18% in controls and 28% in patients, Arg/Pro frequency was 56% and 66%, Pro/Pro genotype was 8% in controls and 8% in patients. No significance was observed for breast cancer risk with either Arg/Arg or Pro/Pro genotype in codon 72 polymorphism. Similarly, mutation analysis of exon 7 codon 249 revealed that 72% of breast cancer patients have mutation, which is not statistically significant. However, there is a strong association between increase in exon 7 codon 249 mutation and exposure to pollution. Conclusion: The results suggested that there is no risk for exon 4 with Arg/Arg or Pro/Pro polymorphisms in the $p53$ gene and there is no strong correlation between breast cancer patients and mutation in exon 7 codon 249 in South Indian women.

• Tuberculosis and Respiratory Diseases
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• v.41 no.4
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• pp.339-353
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• 1994

Background : The p53 gene codes for a DNA-binding nuclear phosphoprotein that appears to inhibit the progression of cells from the G1 to the S phase of the cell cycle. Mutations of the p53 gene are common in a wide variety of human cancers, including lung cancer. In lung cancers, point mutations of the p53 gene have been found in all histological types including approximately 45% of resected NSCLC and even more frequently in SCLC specimens. Mutant forms of the p53 protein have transforming activity and interfere with the cell-cycle regulatory function of the wild-type protein. The majority of p53 gene mutations produce proteins with altered conformation and prolonged half life; these mutant proteins accumulate in the cell nucleus and can be detected by immunohistochemical staining. But protein overexpression has been reported in the absence of mutation. p53 protein overexpression or gene mutation is reported poor prognostic factor in breast cancer, but in lung cancer, its prognostic significance is controversial. Method : We investigated the p53 abnormalities by nucleotide sequencing, polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP), and immunohistochemical staining. We correlated these results with each other and survival in 75 patients with NSCLC resected with curative intent. Overexpression of the p53 protein was studied immunohistochemically in archival paraffin- embedded tumor samples using the D07(Novocastra, U.K.) antibody. Overexpression of p53 protein was defined by the nuclear staining of greater than 25% immunopositive cells in tumors. Detection of p53 gene mutation was done by PCR-SSCP and nucleotide sequencing from the exon 5-9 of p53 gene. Result: 1) Of the 75 patients, 36%(27/75) showed p53 overexpression by immunohistochemical stain. There was no survival difference between positive and negative p53 immunostaining(overall median survival of 26 months, disease free median survival of 13 months in both groups). 2) By PCR-SSCP, 27.6%(16/58) of the patients showed mobility shift. There was no significant difference in survival according to mobility shift(overall median survival of 27 in patients without mobility shift vs 20 months in patients with mobility shift, disease free median survival of 8 months vs 10 months respectively). 3) Nucleotide sequence was analysed from 29 patients, and 34.5%(10/29) had mutant p53 sequence. Patients with the presence of gene mutations showed tendency to shortened survival compared with the patients with no mutation(overall median survival of 22 vs 27 months, disease free median survival of 10 vs 20 months), but there was no statistical significance. 4) The sensitivity and specificity of immunostain based on PCR-SSCP was 67.0%, 74.0%, and that of the PCR-SSCP based on the nucleotide sequencing was 91.8%, 96.2% respectively. The concordance rate between the immunostain and PCR-SSCP was 62.5%, and the rate between the PCR-SSCP and nucleotide sequencing was 95.3%. Conclusion : In terms of detection of p53 gene mutation, PCR-SSCP was superior to immunostaining. p53 gene abnormalities either overexpression or mutation were not a significant prognostic factor in NSCLC patients resected with curative intent. However, patients with the mutated p53 gene showed the trends of early relapse.

• Journal of Gastric Cancer
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• v.10 no.3
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• pp.91-98
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• 2010

Purpose: Silent mating-type information regulation 2 homologue 1 (SIRT1) is a nicotinamide adenine dinucleotide-dependent deacetylase. SIRT1 plays an important role in the regulation of cell death/survival and stress response in mammals. The aim of this study was to investigate whether the SIRT1 gene is involved in the development or progression of gastric cancers. Materials and Methods: SIRT1 and p53 genes in 86 gastric cancers were examined for genetic alterations by PCR-single strand conformation polymorphism sequencing, as well as SIRT1 protein expression in 170 gastric cancers by immunohistochemistry. Results: In the genetic analysis, we found SIRT1 and p53 mutations in two and 12 cases, respectively. Two missense mutations, c.599 C>T (T200I) and c.1258 G>A (E420K), were detected in the SIRT1 gene coding region. The SIRT1 and p53 mutation were found in mutually exclusive gastric cancers. The immunohistochemistry revealed that SIRT1 overexpression was found in 95 (55.9%) of 170 gastric cancers. Altered SIRT1 expression was not statistically associated with clinicopathological parameters, including tumor differentiation, location, lymph node metastasis, or p53 expression. Two cases with an SIRT1 mutation showed increased SIRT1 expression. Conclusions: These results suggest that genetic alterations and overexpression of the SIRT1 gene may contribute to gastric cancer development.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.1
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• pp.45-52
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• 2000

Nowadays, there are a lot of evidence that mutation of the p53 tumor suppressor gene is one of the most common genetic abnormalities in neoplastic progression. In this study, we analyzed 20 specimens of oral tumors(squamous cell carcinoma 14 cases, ameloblastoma 3 cases, adenoid cystic carcinoma 2 cases, malignant schwannoma 1 case)using polymerase chain reaction and direct sequencing which used an automated DNA sequencer and software for detection of mutations. Polymerase chain reactions were performed with 4 sets of primers encompassing exon 5, 6, 7, 8, and direct sequencing method was employed. The results were as followings. 1. We detected 10 point mutations out of 20 specimens (50%). 2. The genetic alterations included 7 mis-sense mutations resulting in single amino acid subtitutions, 2 silent mutations, 1 non-sense mutations encoding a stop codon. 3. Mutations were mostly in exon 7(7 out of 10 mutations, 70%) and involved codons 225, 234, 235, 236, 238, 247. 4. Therse were 4 cases of $T{\rightarrow}A$ transversion, 2 cases of $C{\rightarrow}A$ transversion, $A{\rightarrow}G$ transition, 1 case of $C{\rightarrow}G$, $T{\rightarrow}G$ transversion respectively. 5. We could find out point mutations more conveniently using PCR - Automated Direct Sequencing method.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.2
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• pp.139-148
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• 1999

Oral cancer is a common neoplasm in humans and etiologic mechanism is not well known, so treatment and evaluation of oral cancer is difficult problem. Traditional TNM classification between prognosis of tumors and classification of histopathologic differentiation has problem like lack of objectivity through operators. In molecular biology, cancer is developed by alteration of activation of oncogene and/or inactivation of tumor suppressor gene. The p53 gene, one of the tumor suppresor genes, is believed to play an important role through mutation and overexpression in the progression of human cancers. The p53 mutation is most frequent genetic disorder in humans. The Cyclin D1 has tumor suppresion activity by regulation of cell cycle. The Cyclin D1 regulate activity of Rb tumor suppresor gene by stimulation of CDK4 The purpose of this study was to observe the expression of p53 protein and Cyclin D1 in oral squamous cell carcinoma, and to get expectation of the malignancy and prognosis of oral squamous cell carcinoma. Using the 15 cases of squamous cell carcinoma and the microscopic H&E and immunohistochemical stain. We divided it into 3 groups according to the stain extent, clinical stage and histologic differentiation. The results were as follows1.In the features of immunohistochemical stain of 15 cases of squamous cell carcinoma, positive reaction of p53 was identified in 8 cases (53.3%) and positive reaction of cyclin D1 was identified in 3 cases (20%). Both positive reaction of p53 protein and Cyclin D1 was show in only one case. 2.8 of p53 positive cases were linked in 87.5% of the end stage tumor, 62.5% of neck node involvement, 87.5% of poorly and moderately histopathplogic differentiation. 3. All 3 of Cyclin D1 positive cases were linked in the end stage tumor, neck node involvement, poorly and moderately histopathologic differentiation. From above results, expression of p53 protein was identified in 53.3% of 15 cases and these results mean oral squamous cell carcinoma was drived by mutation of p53 protein. Especially, highly positive reaction of p53 protein and Cyclin D1 was identified in cases that involvement of neck lymph node and the end stage tumors and it means that the evaluation of p53 protein and Cyclin D1 was useful for evaluation of malignant tumor as specific tumor marker.

• Journal of Gastric Cancer
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• v.1 no.1
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• pp.10-16
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• 2001

Purpose: The p53 protein is a tumor supressor gene, and its mutation is associated with biologic aggressiveness. CD44v6, one of the CD44 family, is a cell surface glycoprotein that plays a role in cancer invasion and metastasis. Vascular endothelial growth factor (VEGF) is another recently identified growth factor with significant angiogenic properties. The purpose of this study was to investigate p53, CD44v6, and VEGF expressions to determine whether degree of expression was related to pathological parameters such as Lauren's classification, depth of invasion, and lymph node metastasis. Materials and Methods: Immunohistochemical stains of p53, CD44v6, and VEGF in formalin-fixed paraffin-embedded tissue sections of 125 gastric adenocarcinomas were done. Results: The overall expression rates of p53, CD44v6, and VEGF were $54.4\%$ (68/125), $36.8\%$ (46/125), and $48.0\%$ (60/125), respectively. The p53, not CD44v6 and VEGF was higher in intestinal-type gastric carcinomas by Lauren's classification. The expressions of p53, CD44v6, and VEGF were statistically correlated with depth of tumor invasion. The expression of CD44v6 was higher in the lymph node metastatic group than in the negative group. The p53 expression was significantly associated with VEGF expression. Conclusions: These data suggest that the expressions of p53, CD44v6, and VEGF are biologically related to malignancy. The p53 and CD44v6 expressions are independent; however, p53 gene mutation is one of the contributing factors to VEGF expression in gastric adenocarcinoma.

• IMMUNE NETWORK
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• v.1 no.3
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• pp.221-229
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• 2001

Background: Inactivation of tumor suppressor genes is believed to be important in the development of many human malignancies. Recently, several lines of evidence have indicated that the wild type p53 gene located at 17p13.3, may function as a tumor suppressor gene and that a mutant p53 gene could promote transformation by inactivating normal p53 function in a dominant negative fashion. These broad spectrum of p53 mutation in human cancers provide that mutant p53 and their protein may be potential targets of tumor diagnostic and therapeutic interventions. Method: Colony formation was performed to investigate growth suppressional ability. p53 expression pattern was examined by western blot and p53-mediated transactivation ability was assessed by CAT activity. SNU C2A cells were observed in apoptotic aspects induced by etoposide and $H_2O_2$ treatment, detecting sensitivity on agent, DNA fragmentation through agarose gel, chromatin condensation by fluorescence microscope, and cell cycle distribution by FACS. Result: 1) p53 mutant his179arg ($histidine{\rightarrow}arginine$) detected in SNU C2A cells lost transcriptional activity and growth suppression ability, showing dominant negative effect on its wild type p53. 2) Etoposide-treated SNU C2A cells induced apoptosis, exhibiting dramatic reduction of cell growth, DNA fragmentation, nuclear condensation formation of apoptotic body and increment of sub-G1 cell fraction. 3) Etoposide and $H_2O_2$-treated SNU C2A cells have no high increase of p53 expression and overexpressed p53 protein changed localization, from cytoplasm to nucleus. Also, p53-mediated transcriptional activity was increased by agents-treatment. Conclusion: SNU C2A cells coexpress wild-type and mutant p53 protein induced apoptosis in the condition on DNA damage, through localizational shift from cytoplasm to nucleus of p53 protein rather than the induction of p53 protein. SNU C2A cells derived mutant p53 his179arg abrogated both the growth supression ability and transactivational activity, showing inhibition effect on transcriptional activity of wild type p53, but did not repress the activity of wild type p53 in SNU C2A cells owing to dominant activity of wild type. These cell condition may provide new gene therapeutic implications leading effective antiproliferation of cell when mutant and wild-type p53 protein were co-expressed in cell.