SEARCH · PubMed Health

Results for “TP53”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources

PubMed2005

A substantial proportion of microsatellite-unstable colon tumors carry TP53 mutations while not showing chromosomal instability.

Chromosomal instability in colon tumors implies the presence of numerical and structural chromosome aberrations and is further characterized by the absence of microsatellite instability and the occurrence of KRAS and/or TP53 mutations. In a previous screening of 194 colon tumors for both microsatellite instability and TP53 mutation, we found 25 microsatellite-unstable tumors, in 9 (36%) of which, presumed to be chromosomally stable, there were TP53 mutations. This prompted us to investigate whether a TP53 mutation in these microsatellite-unstable tumors would be an indicator of chromosomal instability, that is, whether this would be a category of tumors showing both microsatellite and chromosomal instability. For chromosomal instability assessment, we performed array-comparative genomic hybridization analysis of tumor and control DNA extracted from formalin-fixed, paraffin-embedded stage III colon tumor specimens. The array consisted of 435 subtelomere-specific BACs. We compared all but one (whose DNA was of bad quality) of the microsatellite-unstable TP53 mutation-containing tumors (8) with a similarly sized group of microsatellite-unstable tumors without TP53 mutation (11). Microsatellite-unstable tumors with a TP53 mutation showed on average 0.9 aberrations (range 0-3) when assessed with this array system. Those without a TP53 mutation showed on average 0.7 aberrations (range 0-2). Thus, microsatellite-unstable tumors showed few chromosomal abnormalities regardless of TP53 mutation status. Because, in our study, the microsatellite-stable tumors had on average 3.4chromosomal abnormalities (range 0-7), a clear difference exists between microsatellite-unstable and -stable tumors. Because a substantial proportion of microsatellite-unstable colon tumors carry a TP53 mutation while showing relativelyfewchromosomal aberrations, a TP53 mutation in these tumors cannot be considered to be an indicator of chromosomal instability.

Chromosomes, Artificial, Bacterial↗

PubMed2005

TP53 alterations and patterns of carcinogen exposure in a U.S. population-based study of bladder cancer.

The molecular pathology of bladder cancer has been the subject of considerable interest, and current efforts are targeted toward elucidating the interrelationships between individual somatic gene loss and both etiologic and prognostic factors. Mutation of the TP53 gene has been associated with more invasive bladder cancer, and evidence suggests that TP53 mutation, independent of stage, may be predictive of outcome in this disease. However, there is no consensus in the literature that bladder carcinogen exposure is associated with inactivation of the TP53 gene. Work to date has been primarily hospital based and, as such, subject to possible bias associated with selection of more advanced cases for study. We examined exposure relationships with both TP53 gene mutation and TP53 protein alterations in a population-based study of 330 bladder cancer cases in New Hampshire. Tobacco smoking was not associated with TP53 alterations. We found a higher prevalence of TP53 inactivation (i.e., mutation and nuclear accumulation) among hair dye users (odd ratio [OR] = 4.1; 95% confidence interval [CI] 1.2-14.7), and the majority of these mutations were transversions. Men who had "at risk" occupations were more likely to have mutated TP53 tumors (OR = 2.9; 95% CI 1.1-7.6). There also was a relative absence of TP53 mutation (OR = 0.4; 95% CI 0.0-2.9) and TP53 protein alterations (OR = 0.6; 95% CI 0.3-1.4) in bladder cancers from individuals with higher arsenic exposure. Our data suggest that there is exposure-specific heterogeneity in inactivation of the TP53 pathway in bladder cancers and that integration of the spectrum of pathway alterations in population-based approaches (capturing the full range of exposures to bladder carcinogens) may provide important insights into bladder tumorigenesis.

Amino Acid Substitution↗

PubMed1994

TP53 gene mutations and CCND1 gene amplification in head and neck squamous cell carcinoma cell lines.

Mutations of the tumor-suppressor gene TP53 and amplification of CCND1 gene have been reported to occur frequently in head and neck squamous cell carcinomas (HNSQCC). In experimental systems, TP53 mutations have been shown to lead to genomic instability, including an increased propensity for gene amplification. We have examined 16 HNSQCC cell lines for the association between TP53 over-expression/mutation and CCND1 amplification. p53 over-expression was detected in 50% of the cell lines by immunohistochemistry using the monoclonal antibody (MAb) PAb1801. TP53 mutations were also detected in 50% of the cell lines by analysis of single-strand conformation polymorphism (SSCP) and DNA sequencing of exons 4 through 9. Six cell lines showed TP53 mutations and over-expression of the protein, 2 cell lines showed TP53 mutations but no p53 expression, and 2 cell lines showed over-expression of p53 protein but no TP53 gene mutations. CCND1 amplification was found in 38% of the cell lines by Southern blot analysis. Only 1 cell line showed both TP53 mutation and CCND1 amplification, whereas 7 of 8 cell lines with TP53 mutations had no CCND1 amplification. pRb expression was detected by Western blot analysis, and the level of pRb did not correlate with either CCND1 amplification or TP53 mutation. Our findings suggest that TP53 mutation and CCND1 amplification are common genetic alterations in HNSQCC and that the occurrence of either genetic event may be sufficient to abrogate normal cell cycle control.

Carcinoma, Squamous Cell↗

PubMed2006

Molecular profiling of bladder tumors based on the detection of FGFR3 and TP53 mutations.

PURPOSE: On a routine basis we performed systematic molecular screening for FGFR3 and TP53 mutations in 121 bladder tumors. We then specifically analyzed the predictive value of the recurrence of FGFR3 and TP53 genotypes in superficial lesions. MATERIALS AND METHODS: The FGFR3 gene was analyzed by direct sequencing of exons 7, 10 and 15, whereas TP53 status was determined using the p53 functional assay in yeast. RESULTS: We identified a missense FGFR3 mutation in 66% of pTa, 26% of pT1 and 12% of pT2 tumors. Of activating FGFR3 mutations 54% and 85% were found in low G1 and intermediate G2 grade tumors, respectively, but in only 20% of high grade G3 tumors. We detected inactivating TP53 mutations in 10% of pTa, 42% of pT1 and 58% of pT2 tumors. Moreover, TP53 mutations were found only in 23% of grade G1 and 3% of grade G2 tumors but in 44% of high grade G3 tumors. When the 2 genotypes were combined, we observed that 58% of pTa tumors had the (mutant FGFR3, WT TP53) genotype, whereas 58% of invasive lesions harbored the inverse genotype (WT FGFR3, mutant TP53). The (mutant FGFR3, WT TP53) genotype and the (WT FGFR3, mutant TP53) genotype were detected in 23% and 38% of pT1G3 tumors, respectively. In the subgroup of 92 patients with superficial pTa-T1 bladder tumors we did not find that the TP53 or FGFR3 genotype alone or combined had a predictive value for tumor recurrence. CONCLUSIONS: Our data again represent solid proof for the pivotal role of FGFR3 and TP53 mutations in superficial and invasive bladder tumors, respectively. However, other molecular markers should be identified for borderline pT1G3 bladder tumors, which are probably at the crossroads of these 2 distinct molecular pathways.

Aged↗

PubMed1999

The TP53 genotype but not immunohistochemical result is predictive of response to cisplatin-based neoadjuvant therapy in stage III non-small cell lung cancer.

BACKGROUND: The cytotoxic effects of cisplatin and anthracyclins have been attributed to apoptosis induction, which has been recognized as a major function of the TP53 gene. The TP53 gene appears to be mutated in about 50% of cases of non-small cell lung cancer. A possible dependence of chemotherapy response on TP53 genotype was evaluated retrospectively in a group of patients with advanced non-small cell lung cancer and induction treatment. METHODS: Patients with complete or partial remission were compared with those with stable or progressive disease with respect to TP53 genotype and overall survival. Mutations in the TP53 gene were detected by complete direct sequencing (exons 2-11). RESULTS: A normal TP53 genotype proved to be significantly associated with major response to chemotherapy (P <.001). Overall, no association was found between p53 protein expression and TP53 genotype. A normal TP53 genotype was found to be highly sensitive in predicting response to treatment, whereas a mutant genotype was revealed to be specific in predicting lack of response. The difference in overall length of survival was significant between patients exhibiting a normal TP53 genotype (corresponding to those whose disease responded to chemotherapy) and patients showing mutant TP53 genotype (corresponding to those who had disease resistant to chemotherapy, P =.027). CONCLUSIONS: In a small cohort of patients with advanced non-small cell lung cancer we found a direct link between normal TP53 genotype and response to cisplatin-based induction treatment and also between mutant genotype and resistance to treatment, whereas p53 immunohistochemical result was predictive of neither.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1998

5' region and exon 7 mutations of the TP53 gene in two cases of B-cell prolymphocytic leukemia.

We previously found that cases of typical B-chronic lymphocytic leukemia (CLL), atypical B-CLL with t(11;14) and mantle cell lymphomas characterized by rapid progression of the disease and resistance to therapy, had mutations of the TP53 gene. In this paper, abnormalities of the TP53 gene were investigated in two cases of prolymphocytic leukemia, one with t(11;14)(q13;q32), evolving from atypical CLL (patient 1), and one presenting as a de novo condition (patient 2). TP53 DNA was investigated by Southern blot and PCR-SSCP analysis, and TP53 expression was investigated by Northern blot analysis and immunocytochemistry. C-MYC and BCL-1/PRAD1 gene expression were also investigated. Restriction enzyme analysis of TP53 DNA in patient 1 showed alteration of fragments including exon I and intron I, and, in both patients, a specific loss of TP53 DNA. In patient 2, PCR direct sequencing showed in exon VII a 9 bp deletion including codons 252-254. In patient 1, TP53 RNA and protein were not found, indicating that the unusual 5' rearrangement has affected TP53 gene expression. By contrast, patient 2 exhibited detectable TP53 RNA and protein. Detectable but weak BCL-1/PRAD1 RNA was present in both patients, whereas C-MYC RNA expression was clearly present only in case 1. The presence of TP53 hemizygous mutations in both patients suggests that TP53 abnormalities may be important in the pathogenesis of prolymphocytic leukemia (PLL), and may possibly account for the frequent resistance to therapy observed in this disease.

Aged↗

PubMed1999

Mutation analysis of BRCA1, TP53, and KRAS2 in ovarian and related pelvic tumors.

Cancer may be viewed as a genetic disease resulting from critical mutations that disrupt normal cell growth. To characterize the involvement of the BRCA1 and TP53 tumor suppressor genes and of the KRAS2 protooncogene in gynecologic cancer, mutation analysis of these genes was conducted in pelvic tumors of 85 patients that included 49 epithelial ovarian carcinoma cases. The 85 pelvic tumors contained 5 tumors with BRCA1 mutations, 33 with TP53 mutations, and 1 with a KRAS2 mutation. Each of the BRCA1 and KRAS2 mutations, and 25 of the TP53 mutations, were in ovarian carcinomas. Four of the BRCA1 mutations were germline and 1 was somatic. The 4 patients with germline BRCA1 mutations had an early age of disease onset (33-48 years) relative to the mean age of onset (58 years) of all 49 ovarian carcinoma patients, and 3 of these 4 patients had a family history of ovarian or breast cancer. None of the 4 tumors with germline BRCA1 mutations had a KRAS2 mutation or a TP53 mutation, despite a 51% frequency of TP53 mutations in the 49 ovarian carcinomas. Three of the 4 tumors with germline BRCA1 mutations retained a wild-type BRCA1 allele. The tumor with the somatic BRCA1 mutation contained a TP53 mutation and had no evidence for wild-type BRCA1 and TP53 alleles. These data suggest that both BRCA1 and TP53 were inactivated in 1 of 49 ovarian carcinomas. Moreover, mutational inactivation of both BRCA1 and TP53 did not occur in 4 tumors with a germline BRCA1 mutation. It has been proposed that tumorigenesis in cells with a heterozygous BRCA1 mutation requires inactivation of the wild-type BRCA1 and TP53 alleles, which results in genomic instability and acquisition of mutations in protooncogenes. Clearly, mutational inactivation of TP53 and the wild-type BRCA1 allele in ovarian tumors with a heterozygous, germline BRCA1 mutation is not an absolute requirement for tumor formation. It is possible that these alleles may be inactivated by nonmutational mechanisms or that other tumor formation pathways exist.

Adult↗

PubMed1999

Hereditary TP53 codon 292 and somatic P16INK4A codon 94 mutations in a Li-Fraumeni syndrome family.

Li-Fraumeni syndrome is an autosomal dominant disorder that is characterized by various types of cancer in childhood and adult cases. Although hereditary TP53 mutation is very rare in different human cancers, it has been frequently reported in Li-Fraumeni syndrome. On the other hand, hereditary mutations of TP57KIP2, P15INK4B, and P16INK4A, which affect the cell cycle similar to TP53, were observed in some types of cancer. In a Turkish family with the diagnosis of Li-Fraumeni syndrome, we analyzed the mutation pattern of TP53, P57KIP2, P15INK4B, and P16INK4A in the peripheral blood, and loss of heterozygosity (homo/hemizygous deletion) pattern of TP53 and P15INK4B/P16INK4A in two tumor tissues. The propositus had a seminoma, his daughter a medulloblastoma, and one of his healthy cousins, a TP53 codon 292 missense point mutation (AAA-->ATA; Lys-->Ile) in the peripheral blood cells. Tumor tissue obtained from the propositus with the seminoma revealed loss of heterozygosity in the TP53 gene. In the analyses of tumor tissues from the propositus and his daughter, a P16INK4A codon 94 missense point mutation (GCG-->GAG; Ala-->Glu) was observed with the hereditary TP53 mutation. P16INK4A codon 94 mutation observed in our family is a novel mutation in Li-Fraumeni syndrome. No other gene alteration in TP53, P57KIP2, P15INK4B, and P16INK4A was observed. Existence of the P16INK4A mutation and the hereditary TP53 mutation with or without loss of heterozygosity in the TP53 gene (seminoma/medulloblastoma) may be evidence for a common mechanism involved in tumorogenesis. The gene alterations in TP53 and P16INK4A genes may be used as tumor markers in our family.

Adult↗

PubMed2026

High-grade serous ovarian cancer is associated with increased TP53 mutation burden in uterine lavage.

High grade serous ovarian cancer (HGSC) has low survival partly due to the lack of methods for detection, diagnosis, and risk prediction. TP53 mutations, which drive HGSC, are found in gynecological tissues as the result of somatic evolution, but it is unknown whether an excess of mutations is linked to ovarian cancer. Here we investigate if TP53 mutation burden measured in uterine lavage, a minimally invasive gynecological liquid biopsy, can discriminate between patients with and without HGSC. We used ultradeep TP53 duplex sequencing (>15,000x duplex depth) to detect TP53 mutations in uterine lavage collected pre-operatively in 278 patients undergoing gynecological surgery for pelvic masses (average risk) or cancer risk-reduction (high risk). All lavages contained multiple TP53 mutant clones, which were used to quantify TP53 mutation burden frequency (MBF). Average risk patients with HGSC had significantly higher TP53 MBF independently of age and other risk factors (77% sensitivity, 89% specificity, AUC = 0.88). Excluding tumor TP53 clonal mutations from the lavage MBF calculation maintains this association, suggesting that it is the overall TP53 somatic mutation burden (rather than the discovery of the specific tumor driver mutation) that identifies HGSC. These results demonstrate that TP53 somatic mutations are common in uterine lavage but more abundant in patients with HGSC, highlighting a connection between TP53 somatic evolution and ovarian cancer. Uterine lavage offers a minimally invasive approach that could be valuable to identify patients with HGSC.

Journal Article↗

PubMed1997

Genomic instability and poor prognosis associated with abnormal TP53 in breast carcinomas. Molecular and immunohistochemical analysis.

Alterations of the TP53 gene were analyzed in samples from 87 primary breast cancer patients, using molecular and immunohistochemical approaches. Mutations were detected in 17% of the samples, using polymerase chain reaction (PCR) and constant denaturant gel electrophoresis (CDGE) on exons 5-8 of the TP53 gene, and were confirmed by sequencing. Abnormal TP53 protein staining was found in 55% of the primary samples, using the monoclonal TP53 antibody DO7. A statistically significant association was found between TP53 mutations and abnormal protein staining (p = 0.002). Our results suggest that dysfunction of the TP53 protein is associated with tumor progression, as we found an association between TP53 abnormalities and accumulation of genetic lesions, measured as overall allelic imbalance (AI), homogeneously staining regions (HSR) and strong ERBB2 overexpression. Furthermore, patients with TP53 mutation had a highly elevated risk of dying from breast cancer during the study period (p < 0.001, RR = 10.68) at a median follow-up time of 42 months. Abnormal TP53 staining was much more frequent than the mutations, but it was not of prognostic significance, whereas strong staining was an independent prognostic factor. We therefore conclude that loss of functional TP53 leads to genetic instability, resulting in poorer short-term prognosis, and that only strong staining of TP53, and not abnormal protein staining in general, is of prognostic significance.

Adult↗

PubMed2004

Accumulation, activation and interindividual variation of the epidermal TP53 protein in response to ionizing radiation in organ cultured human skin.

In this study, we examined effects of low-dose ionizing radiation on organ cultured human foreskin and, in particular, on the epidermis. Diagnostic, therapeutic, natural environmental and incidental exposures to moderate to low doses of radiation are inevitable and, although information on cultured cells continues to accumulate, little is known about the effects of low-dose radiation on human tissues. Our hypothesis is that ex vivo organ cultured foreskin is a simple and reliable model to study the biochemical effects of low-dose radiation exposure on skin. A model such as this will aid in the identification and quantification of low-dose radiation-induced changes in proteins in human skin and may be useful in the development of a precise, non-invasive, and reliable assay of exposure. In this work, several aspects of skin responses to culture conditions and radiation were examined. The responses of epidermal TP53 from organ cultured skin irradiated in medium with and without serum were found to be similar. TP53 levels in organ cultured neonatal foreskin epidermis were then examined for baseline TP53 expression. After an initial increase at 4 h, the TP53 D01 signal returned to low steady-state levels for at least 72 h. Irradiated skin samples from different individuals revealed variations in the TP53 D01 signal. The dose and temporal response of dermis and epidermis to radiation were examined by Western blotting from 0 to 24 h after exposure. After irradiation and incubation, the epidermis was removed and assayed by Western blotting and was found to have increases in the TP53 D01 epitope and the TP53 phosphoserine 15 (TP53-S15p) epitope that reached a maximum at about 3 h. In the epidermis, doses of 1-5 cGy of radiation were detectable with the TP53 D01, and CDKN1A antibodies and doses greater than 10 cGy were detectable with the TP53-S15p antibody. When the dermis was compared to epidermis, it was found that dermis had a smaller response to radiation and more phosphorylated TP53.

Culture Techniques↗

PubMedDate not supplied

Tissue polypeptide antigen (TPA) in comparison with mutations of tumour suppressor gene P53 (TP53) in patients with bladder cancer.

BACKGROUND: Tissue polypeptide antigen (TPA) is a circulating complex of polypeptide fragments from cytokeratins 8, 18 and 19. It is a tumour-related protein. TPA is an indicator of higher cell proliferation. One function of TP53 is the suppression of apoptosis. TP53 mutations are frequently correlated with tumour development in bladder cancer. One function of TP53 is the suppression of apoptosis. We compared TPA expression and TP53 mutation analysis in tumour-free and bladder cancer patients. MATERIALS AND METHODS: We examined 93 patients with bladder cancer, 24 patients with benign urological diseases and a control group of 18 healthy individuals. TPA concentration was measured by immunoluminometric assay with LIA-mat TPA-M Prolifigen. The normal cut-off value was defined at 47 U/I for serum and at 60 U/mmol for creatinine. Screening for TP53 mutations in tissue and urine sediment, amplification of the TP53 gene by polymerase chain reaction (PCR) for the exons 5, 6, 7 and 8 and temperature gradient gel electrophoresis (TGGE) were used to analyse the mutations. Statistical analysis included ROC, Mann-Whitney U-Test and Pearson's correlation. RESULTS: For superficial bladder cancer the mutation frequency in TP53 was 44.8%. We found elevated TPA levels in 45.5% in serum and 36.1% in urine. For invasive bladder cancer the mutation frequency in TP53 was 79.2%. Elevated TPA levels were found in 57.7% in serum and in 58.3% in urine. TPA has a sensitivity of 48.9% in serum and 40.4% in urine; the specificity of TPA is 83% in serum and 100% in urine in comparison with healthy individuals. We found no correlation between TPA level and the inflammation status of the patient. CONCLUSION: This study demonstrated that TP53 mutation frequently occurs in higher stages of bladder tumours. There was no TPA level difference between superficial and invasive bladder cancer. TPA is significantly higher in serum (p = 0.012) and in urine (p = 0.002) in patients with bladder cancer in comparison with control group. TPA in serum is significantly higher in patients with mutation of TP53 (p = 0.046) but not in urine (p = 0.173) in comparison with patients with wild-type TP53.

Apoptosis↗

PubMed1996

Prognostic significance of TP53 accumulation in human primary breast cancer: comparison between a rapid quantitative immunoassay and SSCP analysis.

TP53 accumulation in human primary breast carcinomas was studied by a quantitative luminometric immunoassay (LIA), and TP53 gene alterations, exons 5-8, were examined by single-strand conformation polymorphism (SSCP) analysis. In 48 of 142 breast tumor samples, a TP53 gene alteration was identified. In tumor samples without a TP53 gene alteration, the median cytosolic TP53 protein level, as determined by LIA, was 0.4 ng/mg protein (range 0-70.8 ng/mg protein), whereas the median TP53 protein level for tumor samples with a TP53 gene alteration was 10 times higher, i.e., 4.1 ng/mg protein (range 0.1-176.0 ng/mg protein). Despite a significant correlation between the outcome of LIA and SSCP, a disagreement was found in 22% of cases analyzed. Significant correlations were found between TP53 protein accumulation and low estrogen receptor content, and with a shorter relapse-free as well as overall survival, with a median duration of follow-up of 100 months. Due to its rapid and easy performance on routinely prepared cytosols, the LIA for TP53 protein may be useful in evaluating the prognostic impact of TP53 protein accumulation in human primary breast cancer.

Adult↗

PubMed2001

Prognostic significance of K-ras and TP53 mutations in the role of adjuvant chemotherapy on survival in patients with Dukes C colon cancer.

PURPOSE: Mutations in K-ras and TP53 genes are common in colorectal cancer. They affect biologic behavior and might influence chemotherapy susceptibility in these tumors. We investigated whether the survival of patients with Dukes C colon cancer treated with adjuvant chemotherapy is influenced by K-ras and TP53 mutations. METHODS: Mutation screening of the hot spots of the K-ras gene and of the evolutionarily conserved regions of the TP53 gene was performed by denaturing gradient gel electrophoresis technique in formalin-fixed paraffin-embedded specimens of 55 consecutive patients with Dukes C colon cancer treated with adjuvant 5-fluorouracil-based chemotherapy. The median follow-up was 47 (range, 32-66) months. RESULTS: Alterations in the mutation hot spots of K-ras were found at codon 12 (n = 11) and 13 (n = 4) in 15 of the 55 carcinomas (27 percent). No mutation was found at codon 61. Mutations of a probably causative nature in the evolutionarily conserved regions (exons 5-8) of the TP53 gene were found in 24 tumors (44 percent). K-ras and TP53 mutations were found equally in the group with recurrent disease (7/26 (26 percent) and 12/27 (44 percent), respectively) and in the group without recurrences (8/28 (24 percent) and 12/28 (43 percent), respectively). Cancer-specific survival did not differ significantly between patients with K-ras or TP53 or both mutated and nonmutated tumors, respectively (log-rank test: K-ras, P = 0.72 and TP53, P = 0.77; K-ras and TP53, P = 0.8). Also, potentially aggressive K-ras codon 12 and 13 mutations had the same survival as tumors without these mutations (log-rank test; P = 0.73). CONCLUSIONS: Patients with K-ras or TP53 or both mutated Dukes C colon tumors have the same survival as nonmutated tumors when treated with adjuvant chemotherapy. These data suggest that mutations in K-ras or TP53 alone are not prognostic indicators in patients with Dukes C colon cancer receiving adjuvant 5-Fluorouracil-based therapy.

Adult↗

PubMed2005

TP53 promoter methylation in human gliomas.

Methylation of the promoter region of tumor suppressor genes may be associated with transcriptional silencing and tumor progression. The 5' region of the TP53 gene does not contain a CpG island, but a basal promoter region of 85 bp is essential for its full promoter activity. In the present study, we assessed whether TP53 promoter methylation is present in malignant glioma cells and whether this is associated with reduced TP53 expression. Methylation-specific PCR revealed TP53 promoter methylation in three (U87MG, LNT-229, T98G) out of six malignant glioma cell lines studied. Treatment with 5-aza-2'-deoxycytidine (5-aza-dC) led to up-regulated expression of TP53 mRNA and protein in U87MG and T98G cells, suggesting that promoter methylation is associated with reduced expression in some malignant glioma cells. We then assessed TP53 promoter methylation in primary tissue of low-grade gliomas, and observed TP53 promoter methylation in 29/48 (60%) low-grade astrocytomas, 11/18 (61%) oligoastrocytomas, and 31/42 (74%) oligodendrogliomas. Promoter methylation of the p14ARF gene, another gene involved in the TP53 pathway, was detected by methylation-specific PCR in 5/49 (10%) low-grade astrocytomas, 7/18 (39%) oligoastrocytomas, and 15/41 (37%) oligodendrogliomas. Our previous and present data show alterations of at least one of TP53 promoter methylation, p14ARF promoter methylation, and TP53 mutations in 43/49 (88%) of low-grade astrocytomas, 15/18 (83%) of oligoastrocytomas, and 35/42 (83%) oligodendrogliomas, suggesting that disruption of the TP53/p14ARF pathway is frequent in all histological types of low-grade glioma.

Base Sequence↗

PubMed2006

A novel loss-of-function mutation in TP53 in an endometrial cancer cell line and uterine papillary serous carcinoma model.

The etiology of carcinoma of the uterine endometrium (ECa) is poorly understood. However, loss of apoptosis is one of the major factors that allow cancer cells to survive and progress. Hec50co, a poorly differentiated human ECa cell line, is widely used in the investigation of ECa. Previously, Hec50co xenograft tumor model in nude mice developed an advanced phenotype, similar to that of uterine papillary serous carcinoma (UPSC). Importantly, loss-of-function mutation in tumor suppressor TP53 was found in 20-30% of all ECa and >90% of UPSC. Thus, understanding the status of TP53 in Hec50co is essential for using Heco50co as a model for UPSC. To obtain an accurate genotype-phenotype status of TP53 in Hec50co, we performed mutation and functional analysis of TP53 gene of Hec50co by RT-PCR, genomic-PCR, and cloning and expression of mutant and wildtype TP53 alleles. We found a novel 42-bp deletion mutation in the exon6-intron6 splice junction of TP53 (TP53.del42bp) leading to a 113-bp exon6-deleted/skipped transcript was identified in Hec50co. In addition, the other TP53 allele in Hec50co is inactivated through a large deletion. Adenovirus (AD) harboring wildtype full-length TP53 cDNA induces caspase-dependent apoptosis; while the AD-TP53.del42bp allele does not. In addition, messenger RNA of TP53.del42bp allele is stable whereas the protein product of TP53.del42bp allele is made but not stable. Taken together, we demonstrate that Hec50co is a TP53-null cell line possessing one TP53.del42bp allele and the other lost allele and therefore provides an excellent model to dissect the molecular and cellular bases of UPSC and other p53-null cancers.

Alleles↗

PubMed1996

TP53 mutation analyses on breast carcinomas: a study of paraffin-embedded archival material.

The aim of this investigation was to examine the possibility of analysing TP53 mutations in archival paraffin-embedded material with the constant denaturant gel electrophoresis (CDGE) method. We extracted DNA from 193 archival primary breast carcinoma samples, diagnosed in 1981-83; further analysis was possible for 186 of these. TP53 mutations in exons 5-8 were detected with CDGE in 30 samples (16.1%) and 17 of these mutations were confirmed by sequencing. Immunohistochemistry demonstrated TP53 nuclear accumulation in 58 tumours (31%). A strong association between the presence of TP53 mutations and TP53 immunostaining was observed (P < 0.001). Our mutation and immunohistochemistry results are in agreement with other findings based on fresh tumour tissue. TP53 abnormalities were significantly related to high S-phase fraction, low oestrogen receptor (ER) content and high tumour grade. Survival of patients with TP53 abnormalities, in the group as a whole, did not differ from patients with normal TP53. Our study did, however, show that patients with abnormal TP53 had a significantly shorter post-recurrence survival (P = 0.005) than patients with normal TP53.

Amino Acid Sequence↗

PubMedDate not supplied

TP53 protein expression analysis by luminometric immunoassay in comparison with gene mutation status and prognostic factors in early stage endometrial cancer.

Mutations in the TP53 tumor suppressor gene have been shown to significantly correlate with poor prognosis in endometrial cancer. In the present study we have evaluated a luminometric immunoassay (LIA) for quantitative estimation of TP53 protein expression in 65 cytosol preparations from endometrial cancer, previously analyzed for mutations in TP53 exons 4-10. LIA showed high (> or = 0.6 ng/mg protein) expression of TP53 protein in all eight tumors with missense mutation, but high protein levels were also detected in 15 tumors with normal TP53 sequence. All four tumors with nonsense or frameshift mutations had low or no TP53 protein expression. LIA was further evaluated in a retrospective study of 201 cytosol samples from endometrial cancer. TP53 overexpression (> = 0.6 ng/mg protein) was observed in 22% of the tumors and correlated with nonendometrioid histology types (P = 0.005), poorly differentiated tumors (P = 0.001), higher FIGO grade (P = 0.001), DNA nondiploidy (P = 0.002), and high S-phase fraction (P = 0.03). After a median follow-up time of 6.8 years (range 0.7-9.9 years), 22 (13%) progressions were observed in the 175 patients with early stage (I-II) disease. TP53 overexpression (P = 0.04), FIGO grade 3 vs. 1 + 2 (P = 0.01), higher age (P = 0.02), and DNA nondiploidy (P < 0.001) showed significant correlation to shorter progression-free survival in these patients. We conclude that TP53 protein analysis by LIA provides an incomplete correlation to mutation status and cannot substitute for mutation analysis in assessment of prognosis in endometrial carcinoma. In comparison to TP53 overexpression and higher FIGO grades, DNA nonploidy status seems to be a better prognostic indicator to define a subset of early stage endometrial cancer patients who may benefit by adjuvant chemotherapy/radiotherapy.

Aged↗