DNA double-stranded break (DSB) is one of the most catastrophic damages of genotoxic insult. Inappropriate repair of DNA DSBs results in the loss of genetic information, mutation, and the generation of harmful genomic rearrangements, which predisposes an organism to immunodeficiency, neurological damage, and cancer. The tumor repressor p53 plays a key role in DNA damage response, and has been found to be mutated in 50% of human cancer. p53, p63, and p73 are three members of the p53 gene family. Recent discoveries have shown that human p53 gene encodes at least 12 isoforms. Different p53 members and isoforms play various roles in orchestrating DNA damage response to maintain genomic integrity. This review briefly explores the functions of p53 and its isoforms in DNA DSB repair.
Animals ; DNA Breaks, Double-Stranded ; DNA Repair ; Humans ; Mice ; Protein Isoforms ; physiology ; Tumor Protein p73 ; physiology ; Tumor Suppressor Protein p53 ; genetics ; physiology

OBJECTIVETo investigate the mRNA expression and promoter methylation status of p73 gene in the peripheral blood of children with Wilms' tumor (WT), and their relationship.

METHODSForty-five children with WT were selected as the case group, and 15 sex- and age- matched children (without malignancies) who visited the hospital for physical examination or other reasons were selected as the control group. Peripheral blood was collected from both groups. Real-time quantitative PCR and methylation-specific PCR were used to determine the mRNA expression level and promoter methylation status of p73 gene. Their relationship with clinicopathological features and the effect of promoter methylation on mRNA expression of p73 gene were analyzed in the case group.

RESULTSThe relative quantity (RQ) of p73 mRNA in the case group was significantly higher than in the control group (3.2 ± 0.9 vs 1.6 ± 1.1; P<0.01). The positive rate of p73 gene promoter methylation in the case group was significantly lower than in the control group (20% vs 73%; P<0.01). In the case group, the RQ of p73 mRNA was significantly higher in children with methylated p73 gene promoter than in those with unmethylated p73 gene promoter (P<0.01). In children with methylated p73 gene promoter, the RQ of p73 mRNA was significantly higher in the case group than in the control group (P<0.01). In children with unmethylated p73 gene promoter, there was no significant difference in RQ of p73 mRNA between the case and control groups (P=0.810).

CONCLUSIONSAberrant promoter methylation of p73 gene in peripheral blood is one of the gene expression regulations in children with WT, and it is related to the onset and development of WT. The p73 gene may play a role as oncogene in WT patients with p73 gene promoter methylation and mRNA overexpression is associated with promoter methylation status of p73 gene.

Child, Preschool ; DNA Methylation ; DNA-Binding Proteins ; genetics ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; Infant ; Kidney Neoplasms ; genetics ; Male ; Nuclear Proteins ; genetics ; Promoter Regions, Genetic ; RNA, Messenger ; blood ; Tumor Protein p73 ; Tumor Suppressor Proteins ; genetics ; Wilms Tumor ; genetics

OBJECTIVETo study the methylation status of p73 gene promoter in patients with myelodysplastic syndrome (MDS) and explore its significance with clinical prognosis.

METHODSMethylation of p73 promoter was detected in bone marrow cells from 135 MDS patients and 13 healthy controls by methylation-specific PCR (MSP). The results of MSP were confirmed by bisulfite sequencing. The expression of p73 mRNA was detected by real-time quantitative PCR. Primary bone marrow cells from MDS patients were treated with decitabine, the changes of p73 methylation status and p73 mRNA expression were measured. The role of p73 methylation in the prognosis of MDS and the correlated clinical data were explored.

RESULTSp73 hypermethylation was present in 37.04% of MDS cases and patients with high risk MDS (RAEB-1 and RAEB-2) exhibited a significantly higher frequency of p73 methylation than that of low risk MDS (58.8% vs 29.7%, P = 0.002). The expression of p73 mRNA in the methylated group was decreased compared to that of the unmethylated group (P = 0.032). Decitabine treatment decreased the level of p73 methylation and increased the level of p73 transcripts. Patients with p73 methylation progressed rapidly to AML (P < 0.001) and had shorter survival (P = 0.002) than those who did not have p73 methylation. In the multivariate Cox regression model, BM blast and p73 methylation status emerged as independent prognostic factor for overall survival and leukemia free survival.

CONCLUSIONp73 gene methylation is common in patients with MDS and may indicate poor prognosis. p73 may be a therapeutic target in MDS.

Aged ; Case-Control Studies ; DNA Methylation ; DNA-Binding Proteins ; genetics ; Female ; Humans ; Male ; Middle Aged ; Myelodysplastic Syndromes ; genetics ; Nuclear Proteins ; genetics ; Prognosis ; Promoter Regions, Genetic ; Tumor Protein p73 ; Tumor Suppressor Proteins ; genetics

OBJECTIVETo investigate the expression of p73 and c-fos protein and its significance in the development of children hemangioma.

METHODSThe quantitative expressions of p73 and c-fos protein in hemangioma and normal skin were detected by immunohistochemistry.

RESULTSThe expressions of p73 and c-fos protein were strong in proliferative hemangioma while they were very weak in involutional hemangioma and normal skin. There were significant differences between the proliferative and involutional hemangioma or the normal skin in the expressions of p73 and c-fos (P < 0.01). No statistical significances of p73 or c-fos P73 expressions were observed between involutional hemangioma and normal skin (P > 0.05).

CONCLUSIONSP73 and c-fos may play an important role in the development and involution of skin hemangioma.

Child ; Child, Preschool ; DNA-Binding Proteins ; metabolism ; Female ; Hemangioma ; metabolism ; pathology ; Humans ; Infant ; Male ; Neoplasm Staging ; Nuclear Proteins ; metabolism ; Proto-Oncogene Proteins c-fos ; metabolism ; Tumor Protein p73 ; Tumor Suppressor Proteins ; metabolism

OBJECTIVEIt has been proposed that genetic polymorphisms in apoptosis-related genes might be associated with sensitivity of cancer cells to platinum-based chemotherapy. This study examined the relationship between p53 and p73 genetic polymorphisms and the response to platinum-based chemotherapy in patients with advanced non-small cell lung cancer (NSCLC).

METHODSA total of 165 patients with advanced NSCLC treated with platinum-based chemotherapy were genotyped for the p53 codon 72 Pro-->Arg and p73 exon 2 G4C14-->A4T14 polymorphisms using PCR-RFLP and ARMS-PCR assays. Clinical response to the chemotherapy was obtained after 2 to 3 cycles. The adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using unconditional logistic regression model. All statistical tests were two-sided.

RESULTSThe p53 Pro allele carriers had higher response rate than non-carriers (OR = 2.46; 95% CI = 1.11 - 5.45). A higher response rate was also observed for the p73 G4C14/A4T14 or A4T14/A4T14 genotype, compared with the G4C14/G4C14 genotype (OR = 2.22; 95% CI = 1.14 - 4.30). When these two polymorphisms were combined to be analyzed, it was found that the response rate in those carrying the wild-type genotypes at both genes was only 7.7%, whereas the response rates in patients carrying 1, 2, or more than 2 variant alleles of p53 and p73 were 34.8%, 42.2% and 40.7%, respectively.

CONCLUSIONThose results suggest that p53 and p73 polymorphisms may be associated with clinical responsiveness to platinum-based chemotherapy in advanced NSCLC.

Adult ; Aged ; Antineoplastic Agents ; therapeutic use ; Carboplatin ; administration & dosage ; Carcinoma, Non-Small-Cell Lung ; drug therapy ; genetics ; pathology ; Cisplatin ; administration & dosage ; DNA-Binding Proteins ; genetics ; Exons ; Female ; Genotype ; Humans ; Lung Neoplasms ; drug therapy ; genetics ; pathology ; Male ; Middle Aged ; Neoplasm Staging ; Nuclear Proteins ; genetics ; Paclitaxel ; administration & dosage ; Polymorphism, Genetic ; Tumor Protein p73 ; Tumor Suppressor Protein p53 ; genetics ; Tumor Suppressor Proteins ; genetics

BACKGROUNDp73, a homologue of p53, has been located at chromosome 1p36-33, a region of frequently observed loss of heterozygosity in breast cancers. The objective of the present study was to investigate the function of p73 in Japanese with breast cancers.

METHODSSixty Japanese patients with breast cancer were assessed by polymerase chain reaction single strand confirmation polymorphism analysis and direct sequencing to detect the p73 allele. p73 mRNA levels were also determined in 40 out of 60 patients by reverse-transcriptional polymerase chain reaction.

RESULTSWe analyzed the entire open reading frame of the p73 gene by polymerase chain reaction single strand confirmation polymorphism and sequencing, and failed to identify any mutations of p73 in the encoding regions detected. Loss of heterozygosity of p73 was infrequent and only found in 9% of breast carcinomas. We revealed a few polymorphisms with a frequency of 13% - 29%, which had been reported previously. Down-regulation of p73 mRNA expression was observed in tumor tissues in comparison to the normal breast tissues. A significant inverse correlation was found between p73 transcripts and high histological grade, suggesting that down-regulated p73 expression could be related to poor prognosis in those patients.

CONCLUSIONOur results suggest that p73 may serve as a tumor suppressor gene and its expression plays a role in tumorigenesis in Japanese patients with breast cancer.

Breast Neoplasms ; genetics ; metabolism ; pathology ; Carcinoma ; genetics ; metabolism ; pathology ; DNA-Binding Proteins ; genetics ; Female ; Humans ; Loss of Heterozygosity ; genetics ; Middle Aged ; Nuclear Proteins ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Tumor Protein p73 ; Tumor Suppressor Protein p53 ; genetics ; metabolism ; Tumor Suppressor Proteins ; genetics

OBJECTIVE: To study the clinical significance of the expression of p53, p63 and p73 protein and the correlation of p53 and p63 in nasal and paranasal sinus carcinoma (NPSC). METHOD: The immunohistochemical technique was used to detect the expression of p53, p63 and p73 in 67 cases of NPSC, para-cancer tissues and non-cancer tissues. RESULT: The positive rate of p53 and p63 protein in NPSC was significantly higher than that in park cancer tissues and non-cancer tissues (P<0.01), and there were a positive correlation between the expression of p53 and p63 protein in NPSC (P<0.01). But the expression of p73 had no significant difference among NPSC, para-cancer tissues and non-cancer tissues (P>0.05). CONCLUSION There are positive correlation between p53 and p63 protein in NPSC, and they may play an important role in the tumorgenesis of NPSC. The p73 may not be associated with tumorgenesis of NPSC.
Carcinoma, Squamous Cell ; metabolism ; pathology ; DNA-Binding Proteins ; metabolism ; Female ; Humans ; Male ; Middle Aged ; Nose Neoplasms ; metabolism ; pathology ; Nuclear Proteins ; metabolism ; Paranasal Sinus Neoplasms ; metabolism ; parasitology ; Trans-Activators ; metabolism ; Transcription Factors ; Tumor Protein p73 ; Tumor Suppressor Protein p53 ; metabolism ; Tumor Suppressor Proteins ; metabolism

Adenocarcinoma ; genetics ; metabolism ; Adolescent ; Adult ; Aged ; Biomarkers, Tumor ; Child ; Child, Preschool ; DNA-Binding Proteins ; biosynthesis ; genetics ; Female ; Gastric Mucosa ; metabolism ; Genes, Tumor Suppressor ; Humans ; Male ; Middle Aged ; Nuclear Proteins ; biosynthesis ; genetics ; PTEN Phosphohydrolase ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Stomach Diseases ; genetics ; metabolism ; Stomach Neoplasms ; genetics ; metabolism ; Tumor Protein p73 ; Tumor Suppressor Proteins

The purpose of this investigation was to study the variation of p73 gene expression in the apoptotic process of acute myeloid leukemia (AML) cell line U937 induced by methotrexate (MTX). Morphological changes of apoptotic cells were observed with microscopy and Wright's + Giemsa staining. DNA ladder and cell cycle were examined by agarose gel electrophoresis and flow cytometry respectively. Using semi-quantitive reverse transcription-polymerase chain reaction (RT-PCR), the expression of p73 mRNA was examined. Results showed that MTX could induce U937 cell apoptosis effectively. Condensed nuclei, fragmentation of chromosome and DNA ladder were seen after 6 hour following treatment of MTX 5 micro mol/L. Sub-G(1) peak and S + G(2)/M arrest were also determined by FCM, but the quantity of p73 expression was generally constant. In conclusion, U937 cell apoptosis induced by MTX did not change p73 mRNA level.
Acute Disease ; Antimetabolites, Antineoplastic ; pharmacology ; Apoptosis ; drug effects ; genetics ; Cell Cycle ; drug effects ; Cell Division ; drug effects ; DNA, Neoplasm ; drug effects ; genetics ; metabolism ; DNA-Binding Proteins ; genetics ; Flow Cytometry ; Gene Expression Regulation, Neoplastic ; drug effects ; Genes, Tumor Suppressor ; Humans ; Leukemia, Myeloid ; drug therapy ; genetics ; pathology ; Methotrexate ; pharmacology ; Nuclear Proteins ; genetics ; RNA, Messenger ; drug effects ; genetics ; metabolism ; Tumor Protein p73 ; Tumor Suppressor Proteins ; U937 Cells

OBJECTIVETo investigate the relationship between p73 gene and the development and progression of childhood acute lymphoblastic leukemia (ALL).

METHODSThe levels of p73 transcripts in 61 ALL cell lines and 53 childhood ALL patients were assayed using reverse transcriptase-polymerase chain reaction (RT-PCR), and their relationship with the clinicopathological characteristics was analyzed. Besides, the methylation status of p73 exon 1 was analysed by restriction-enzyme related PCR, methylation-specific PCR and bisulfite genomic sequencing in the 61 ALL cell lines.

RESULTSOf the 61 ALL cell lines, 42 showed expression of p73 mRNA, with a negative rate of 31.1%, and of the 53 primary childhood ALL samples, 39 showed expression of p73 mRNA, with a negative rate of 26.4%. Loss of p73 expression was significantly associated with the reduced disease free survival and overall survival of the patients. 39.3% (24/61) of the ALL cell lines showed hypermethylation of p73 exon 1, while normal lymphocytes and most cell lines expressed p73 mRNA were not hypermethylated.

CONCLUSIONThere was a higher negative expression rate of p73 mRNA in childhood ALL. The main mechanism of the loss expression would be the hypermethylation of p73 gene. p73 gene inactivation might play an important role in the pathogenesis of ALL. Examination of p73 mRNA might have clinical significance in predicting prognosis of childhood ALL.

Adolescent ; Cell Line ; classification ; cytology ; metabolism ; Child ; Child, Preschool ; DNA Methylation ; DNA-Binding Proteins ; genetics ; metabolism ; Disease-Free Survival ; Female ; Gene Silencing ; Genes, Tumor Suppressor ; Humans ; Infant ; Male ; Nuclear Proteins ; genetics ; metabolism ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; genetics ; metabolism ; mortality ; RNA, Messenger ; biosynthesis ; Survival Rate ; Tumor Protein p73 ; Tumor Suppressor Proteins