Analysis of Genetic Alterations in TP53 Gene in Breast Cancer - A Secondary Publication

Tumor protein p53 (TP53) mediates DNA repair and cell proliferation in growing cells. The TP53 gene is a tumor suppressor that regulates the expression of target genes in response to multiple cellular stress factors. Key target genes are involved in crucial cellular events such as DNA repair, cell cycle regulation, apoptosis, metabolism, and senescence. TP53 genetic variants and the activity of the wild-type p53 protein (WT-p53) have been linked to a wide range of tumorigenesis. Various genetic and epigenetic alterations, including germline and somatic mutations, loss of heterozygosity, and DNA methylation, can alter TP53 activity, potentially resulting in cancer initiation and progression. This study was designed to screen three reported mutations in the DNA-binding domain of the p53 protein in breast cancer, to evaluate the relative susceptibility and risk associated with breast cancer in the local population. Genomic DNA was isolated from 30 breast tumor tissues along with controls. Tetra and Tri ARMS PCR were performed to detect mutations in the TP53 coding region. For SNPs c.637C>T and c.733C>T, all analyzed cases were homozygous for the wild-type allele ‘C,’ while for SNP c.745A>G, all cases were homozygous for the wild-type allele ‘A.’ These results indicate no relevance of these three SNPs to cancer progression in our study cohort. Additionally, the findings from whole exon sequencing will help to predict more precise outcomes and assess the importance of TP53 gene mutations in breast cancer patients.

Abnormal Change of p53 Gene in Gastric and PrecancerousLesions and APC Gene Deletion in Gastric Carcinoma and Near Tissues

p53 gene mutation (exon4, 5, 6, 7, 8 and intron6) in gastric cancer and precancerous lesions and p53 gene (exon4 and ontron6), APC gene deletion in gastric carcinomas were studied by PCR/SSCP and PCR/RFLP- Results showed mutation rate of p53 in metaplasia, dysplasia and gastric carcinoma was 37. 5 % (3/8), 42. 11 % (8/19), 53. 33 (16/30) respectively- There was significant dif-ference among groups of metaplasia, dysplasia, cancer and normal controls. Noexon8 mutation was found in metaplasia and dysplasia, but 4 cases were found to have exon8 mutation in cancer group. It is suggested that exon8 mutation occurs at the late stage of gastric cancer, but exon 5, 6, 7 mutation occur in the course ofprecancerous lesion to cancer. Loss of heterozygosity (LOH) of exon4, intron6,APC was 47,37 % (9/19), 8. 73% (2/23), 16. 67 % (3/18) respectively. LOH of exon4 had something to do with poor differentiation, lymph node metastasis,depth of invasion- LOH of exon4 may be one of prognostic marker of gastric cancer. We are led to conclude that p53 gene mutation is an early event and perhaps work together with ras oncogene in gastric carcinogenesis

GROWTH INHIBITION OF HUMAN LARYNGEAL CANCER CELL WITH THE ADENOVIRUS-MEDIATED p53 GENE

Objective: In most laryngeal cancers, the function of p53 gene is down regulated. To explore the potential use of p53 in gene therapy of laryngeal cancer, by introducing wild-type p53 into laryngeal cancer cell line via a recombinant adenoviral vector, Ad5CMV-p53 and analyzing its effects on cell and tumor growth. Methods: A human laryngeal cancer, cell line Hep-2 was used. Recombinant cytomegalovirus-promoted adenoviruses containing human wild-type p53 cDNA was transiently introduced into Hep-2 line. The growth suppression of the Hep-2 cells and established s.c. squamous, carcinoma model was examined. The p53 protein expression was detected using immunohistochemical analysis. Results: The transduction efficiencies of Hep-2 cell line were 100% at a multiplicity of 100 or greater. The p53 protein expression peaked on day 2 after infection and lasted far 5 days. In vitro growth assays revealed cell death following Ad5CMV-p53 infected. In vivo studies, Ad5CMV-p53 inhibited the tumorigenicity of Hep-2 cell, and in nude mice with established s.c. squamous, carcinoma, nodules showed that tumor volumes were significantly reduced in mice that received peritumoral infiltration of Ad5CMV-p53. Conclusion: Adenovirus-mediated antitumor therapy carrying the p53 gene is an efficient method to inhibit laryngeal cancer growth. Transfection of laryngeal cancer cells with the wild-type p53 gene via Ad5CMV-p53 is a potential novel approach to the therapy of laryngeal cancer.

DETECTION OF p53 GENE MUTATION OF BRONCHOSCOPIC SAMPLIES IN THE PATIENTS SUSPECTED TO LUNG CANCER

Objective: To determine the feasibility of detecting p53 gene mutations for early diagnosis of lung cancer using the samples from bronchoscopic examination. Methods: Point mutations of the exon 5-8 of p53 gene were detected in 85 bronchoscopic samples of 35 patients suspected to be lung cancer using silver staining PCR-SSCP. Results: p53 gene mutations were founded in 10 of 35 patients(28.6%). The incidence of p53 gene mutations (14.9%) was obviously higher than the cytological positive incidence(2.9%) in samples of sputum, bronchoalveolar lavage and brush, especially for the sputum(27.7%). In the bronchoscopic biopsy specimens, the incidence of p53 gene mutations (12.5%) was lower than that of pathologic positive result (50.0%). However, in view of all the bronchoscopic samples, there was no statistically difference between cytopathologic positive results (11.8%) and the incidence of p53 gene mutations (14.1%). Although the p53 mutations were most common in the samples from the patients bronchoscopically manifested as neoplasm compared with other manifestations, there was no statistical difference. It is valuable to notice that 3 patients with p53 gene mutation merely presented as bronchial inflammation in bronchoscope. Conclusion: Results indicated that the value of detecting p53 gene mutation for the diagnosis of lung cancer using the bronchoscopic samples was more superior to cytological examination and detection of p53 gene mutations in post-bronchoscopic sputum was easy and effective, may be used as a valuable method for early diagnosis of lung cancer.

p53 Gene Mutations in Asbestos Associated Cancers

The accumulation of mutant p53 protein in cancer cells was observed by immunohistochemistry analysis. DNA was extracted from paraffin-embedded tissue. Exons 5, 7 and 8 were amplified and studied by PCR-SSCP and sequencing analysis. Ten cases of asbestos associated cancer tissue were studied, of which five cases had adenocarcinoma, and the other five had mesothelioma, squamous carcinoma, small cell lung cancerl adenosquamous carcinoma and malignant lymphoma respectively. Employing monoclonal antibody PAb1801, five cases were found to be mutant p53 protein mpitive. Seven cases were found to have mutations by PCRSSCP. A total of 7 cases (8 mutations) were found to be positive and 4 cases were found to be opitive by both of these analyses. Of the 8 mutations found by SSCP analysis, 4(50%, 4/8)were clustered in exon 8. A high mutation frequency was noticed in adenocarcinoma (80%,4/5). ffequencing analysis on two specimens revealed two hotspot mutations. In codon 234,TAC for tyrooin was mutated to AAC fOr aspar8gine by a T to A transversion of the first letter. In codon 273, CGT for arginine was mutated to AGT for serine by a C to A transversion of the first letter. ln conclusion, the mutation of p53 gene is common in asbestos associated cancers. However, the mutational spectrum of asbestos associated cancers might be different from that of non-asbestos associated cancers.

DETECTION OF p53 GENE MUTATION IN PLASMA OF PATIENTS WITH GASTRIC CANCER

Objective: To investigated p53 gene mutation in plasma of gastric cancer patients. Methods: DNA extracted from plasma and matched tumor and tumor-adjacent non-cancerous tissues of 96 gastric cancer patients, and DNA from 20 healthy volunteers were studied. Exon 5, 6, 7, and 8 of p53 were amplified by Polymerase Chain Reaction (PCR). The mutation status was analyzed by denaturing high-performance liquid chromatography (DHPLC), followed by direct sequencing of cases with aberrant chromatographic patterns. Results: Heterozygous mutations of p53 gene were detected in 19.9% (19/96) of primary tumor tissues and 5.2% (5/96) of corresponding plasma. All p53 gene mutations detected in plasma DNA consisted with mutations in the matched primary tumor samples. Neither the tumor-adjacent gastric mucosa tissues nor control plasma from healthy volunteers showed p53 gene mutation. No correlation was found between p53 mutation status and clinicopathological features of gastric cancer patients. Conclusion: p53 gene mutation in plasma can be detected in tissues and plasma of gastric cancer patients, which could be applied in screening and surveillance of this disease.

THE RELATIONSHIP OF p53 GENE MUTATION AND TUMORINVASION AND LYMPH NODE METASTASIS IN EARLY GASTRIC CANCER

This study was conducted by determination or mutative p53 gene expression in 32 casesof submucosa early gastric cancer. The relationship of p53 gene mutation and tumorlgenesis andprogress or gastric cancer was evaluated based on the cllnlco-pathological characteristics of early gastric cancer. Results showed that positive rate or P53 Protein expression was 34. 8% in early gastriccancer and p53 mutation related to the hlstology, location or tumor and lymph node metastasis (P <0. 05). Our research suggested that p53 gene ed,resslon closely related to the prognosis of early gastric cancer, and carcinogenesls I,athways may be different according to the positions of stomach.

Function of apoptosis and expression of the proteins Bcl-2,p53 and C-myc in the development of gastric cancer

INTRODUCTIONIn China ,the incidence and mortality of gastric cancer rank the second among all cancers. Recent development of cancer [1-20].The aim of this study was investigat the insight of apoptosis and bcl-2, p53 and C-myc protein expression in the development of gastric cancer .

Overexpression of P53 and its risk factors in esophageal cancer in urban areas of Xi′an

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Clinical utility of anti-p53 auto-antibody: Systematic review and focus on colorectal cancer

Mutation of the p53 gene is a key event in the carcinogenesis of many different types of tumours. These can occur throughout the length of the p53 gene. Anti-p53 auto-antibodies are commonly produced in response to these p53 mutations. This review firstly describes the various mechanisms of p53 dysfunction and their association with subsequent carcinogenesis. Following this, the mechanisms of induction of anti-p53 auto-antibody production are shown, with various hypotheses for the discrepancies between the presence of p53 mutation and the presence/absence of anti-p53 auto-antibodies. A systematic review was performed with a descriptive summary of key findings of each anti-p53 auto-antibody study in all cancers published in the last 30 years. Using this, the cumulative frequency of anti-p53 autoantibody in each cancer type is calculated and then compared with the incidence of p53 mutation in each cancer to provide the largest sample calculation and correlation between mutation and anti-p53 auto-antibody published to date. Finally, the review focuses onthe data of anti-p53 auto-antibody in colorectal cancer studies, and discusses future strategies including the potentially promising role using anti-p53 auto-antibody presence in screening and surveillance.

Analysis of N-ras gene mutation and p53 gene expression in human hepatocellular carcinomas

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Clinical significance of expression of p21 and p53 proteins and proliferating cell nuclear antigen in pancreatic cancer

Objective: To study the clinical significance and effect of p21, p53 protein as well as proliferating cell nuc- lear antigen (PCNA) on the occurrence and develop- ment of pancreatic carcinoma. Method: p21, p53 protein and PCNA expressions were detected in specimens from 30 patients with pancreatic carcinoma and 3 samples of normal pan- creatic tissue by immunohistochemistry. The data were analyzed together with clinical findings. Results: The positive expression rates of p21 and p53 proteins were 75.0% and 57.3% respectively in pan- creatic carcinoma, which were significantly different from those in the normal tissue (P<0.05). p21 and p53 proteins were positively correlated (P<0.05). The positive expression of PCNA was 43.33%± 17.99%, that was significantly higher than that in the normal pancreatic tissue (P<0.05). The expres- sion of PCNA was correlated with the histological grade (P<0.05). The positive expression rate was consistent with the exacerbation of cancer. The ex- pression was also correlated significantly with prog- nosis and p53 expression (P<0.05). Conclusions: The occurrence and development of pancreatic cancer are the result of associated function for many oncogenes and antioncogenes. PCNA may be helpful to identify malignant degree and prognosis of pancreatic cancer.

Maspin subcellular expression in wild-type and mutant TP53 gastric cancers

BACKGROUND Although the role of p53 in the evolution and prognosis of gastric cancer(GC)has been extensively examined,the exact mechanism of action is incompletely understood.In the last years,p53-target genes were supposed to be involved in the p53 pathway.One of them is the tumor-suppressor gene Maspin,which codifies the protein with the same name.Maspin activity depends on its subcellular localization.To our knowledge,the possible role of TP53 gene in Maspin subcellular localization,in GC cells,has not yet been studied in a large number of human samples.AIM To evaluate the possible role of wild-type and mutated p53 in Maspin subcellular localization.METHODS The present study included 266 consecutive patients with GC in which TP53 gene status,and mutations in exons 2 to 11,respectively,were analyzed and correlated with immunohistochemical expression of p53 and Maspin.RESULTS None of the 266 cases showed mutations in exon 9.The rate of TP53 mutations was 33.83%.The mutation rate was slightly higher in distally-located GCs,with a lower degree(≤5 buds/high power fields)of dyscohesivity(P<0.01).The wildtype cases had a longer survival,compared with mutant GCs,especially in patients without lymph node metastases,despite the high depth of tumor infiltration(P=0.01).The Dukes-MAC-like staging system was proved to have the most significant independent prognostic value(P<0.01).The statistical correlations proved that TP53 gene mutations in exon 7 might induce knockdown of Maspin,but wild-type p53 can partially restore nuclear Maspin expression and decrease the metastatic potential of gastric adenocarcinoma cells.CONCLUSION Downregulated Maspin might be induced by mutations in exon 7 of the TP53 gene but wild-type p53 can partially restore nuclear Maspin expression.These findings should be proved in experimental studies.

EXPRESSION OF FRAGILE HISTIDINE TRIAD AND P53 IN NON-SMALL CELL LUNG CANCER

Objective： To investigate the expression offragile histidine triad （FHIT） and p53 protein in non-small cell lung cancer （NSCLC） and explore the relationship between their expressions and the clinicopathological features. Methods： FHIT protein and p53 protein were detected by immunohistochemistry in 76 cases of NSCLCs and matched normal lung tissues. Results： Fifty-one cases （67.1%） showed negative expression of FHIT （apparent reduction or loss） and thirty-seven cases （48.7%） showed p53 positive expression （overexpression）. The difference was significant （P=0.04）. However, there was no significant difference in FHIT expression between the p53-positive group and the p53-negative group （64.9% versus 69.2%, P=0.686）. The negative rate of FHIT protein expression was higher in squamous cell carcinoma than in adenocarcinoma, in moderately and poorly differentiated carcinoma than in well-differentiated carcinoma, and in cases with smoking history than in cases without smoking history （P〈0.05）. There was no relationship between FHIT expression and clinical stage or lymph node metastasis. The negative FHIT expression was not an independent predictor of overall survival （P=0.338）. Conclusion： The frequency of negative expression of FHIT protein is higher than that of positive expression of p53 in NSCLCs. The negative expression of FHIT is independent of the expression of p53. The change of expression of FHIT may play a role in the smoking related lung tumorigenesis while it may have no relationship with the progress of NSCLC or prognosis of the patients.

Detection of apoptotic cells and immunohistochemical study of bcl-2 and p53 gene protein in primary gastric mucosa-associated lymphoid tissue (MALT) lymphoma

To identify the apoptotic cells in gastric MALT lymphoma and its relationship between bcl-2 and p53 gene expression. Methods: TdT-mediated dUTP biotin Nick End labeling (TUNEL) and immuno-histochemistry ABC method were used to display apoptotic cells and the gene protein expression of bcl-2 and p53 independently. Results: Apoptotic indices (AI) in high-grade MALT lymphomas were significantly higher than in mixed-grade group and low-grade group (P<0.05). Bcl-2 was expressed in 83% of low-grade tumors, 61.6% of the median-grade tumors and 43.7% of high-grade tumors. An inverse correlation was observed between the expression of bcl-2 and apoptotic indices. Only 27 cases were p53 positive. The frequency of p53 positivity was significantly increased as the histologic grade advanced (P<0.05). There was also an inverse correlation between the expression of bcl-2 and p53. Conclusion: Apoptosis may be important in tumors development and transmission. p53 and bcl-2 were important regulatory genes of apoptosis and may be associated with transformation from low- grade to high-grade lymphomas.

EXPRESSION OF P53 AND C-MYC IN MOUSE LUNG CANCER INDUCED BY COAL BURNING

Previous epidemiological studies have shown association between coal burning and human lung cancer.To confirm relationship between coal burning and lung cancer formation and progression the expression of p53 and c-myc in 13 mouse lung cancer induced by coal burning smoke and 5 mouse lung tissue control was studied by DNA-RNA in situ hybridization (ISH). Nine of 13 specimens showed c-myc overexpression but it occurred only 1 of adjacent tissue. There was over pression of p53 mRNA in all 13 lung cancer and 5 adjacent tissue. None in the controls was expression of P53 and c-myc detected. When compared to controls,there was significant higher expression of c-myc gene (P=0.002) and p53 gene (P=0.0001 ).The results confirm that overexpression of p53 and c-myc are common molecular events of lung cancer by coal burning smoke and provide further evidence that smoke from coal burning is a causative agent of lung cancer.

THE POTENTIAL DANGER OF HISTOPATHOLOGICALLYNORMAL TISSUES WITH P53 GENE MUTATION INLARYNGEAL CARCINOMA

Objective Possible differences were analyzed between histopathological and molecular biologicalfindings in laryngeal cancer tissues and its adjacent nomal tissues. Methods Laryngeal carcinoma tissues from20 patients were analyzed by PCR-SSCP. Results P53 gene mutations were detected in 25% (5 out of 20) of thecarcinomas. In these patients P53 mutations were detected in histopathologically nomal tissue both within 0.5 cmand more than 0.5cm distant from the nearest cancerous tissue. Conclusion Since the P53 mutation was commonin both cancer tissue the gene mutation may plan an.important role in laryngeal carcinogenesis. Radical excision ofthe tumour is defined by histopathological limits, but"normal" tissue may nevertheless contain the gene mutation,giving rise to the danger of further cancer development. We suggest that the determination of the surgical marginshould be based on a combination of histopathology and molecular biological findings.

腺病毒介导的p53和顺铂的联合应用对胆管癌细胞系QBC939的生长抑制作用

目的 :研究 p5 3基因和顺铂联合应用对胆管癌细胞的作用。方法 :将重组体腺病毒p5 3和顺铂联合作用于人胆管癌细胞QBC939,对 p5 3基因的表达、细胞的生长抑制及机制进行分析。结果 :用Ad -LacZ进行重组腺病毒转导效率的检测 ,发现当MOI为 10 0以上时 ,重组腺病毒可使 90 %以上的培养的人胆管癌QBC939细胞被传导。用RT -PCR方法检测 ,在胆管癌QBC939细胞系中 p5 3无表达。重组体腺病毒能介导外源基因 p5 3在胆管癌QBC939细胞系中高效表达。重组体腺病毒介导的 p5 3在QBC939细胞中表达 ,能抑制QBC939细胞的生长和集落形成。其与顺铂联合应用对QBC939细胞的生长抑制具有明显作用。流式细胞计数证实 p5 3能诱导QBC939细胞发生凋亡并导致其发生G1期阻滞 ,顺铂能诱导QBC939细胞发生凋亡并导致细胞发生明显的G2期阻滞。结论 :p5