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PubMed2005

A novel optical biosensor format for the detection of clinically relevant TP53 mutations.

The TP53 gene has been the subject of intense research since the realisation that inactivation of this gene is common to most cancer types. Numerous publications have linked TP53 mutations in general or at specific locations to patient prognosis and therapy response. The findings of many studies using general approaches such as immunohistochemistry or sequencing are contradictory. However, the detection of specific mutations, especially those occurring in the structurally important L2 and L3 zinc binding domains, which are the most common sites of TP53 mutations, have been linked to patient prognosis and more strongly to radiotherapy and chemotherapy resistance in several major cancers. In this study, the TI-SPR-1 surface plasmon resonance system and Texas Instruments Spreeta chips were used to develop a DNA biosensor based on thiolated probes complementary to these domains. The sensors were able to detect these mutations in both oligonucleotides and PCR products with normal and mutant TP53 DNA, but the difference in hybridisation signal was small. Preliminary experiments to enhance the signal using Escherichia coli mismatch repair proteins, MutS and single strand binding protein were carried out. It was found that MutS was unable to bind to mismatch oligonucleotides, but single strand binding protein was able to bind to single stranded probes, which had not hybridised to the target, resulting in a three-fold increase in the sensitivity of the biosensor. While further work needs to be carried out to optimise the system, these preliminary experiments indicate that the TI-SPR-1 can be used for the detection of clinically relevant mutations in the TP53 gene and that the sensitivity can be increased significantly using single strand binding protein. This system has a number of advantages over current mutation detection technologies, including lower cost, ease of sensor preparation and measurement procedures, technical simplicity and increased speed due to the lack of need for gel electrophoresis.

Biosensing Techniques↗

PubMed2004

Towards fast and inexpensive molecular diagnostic: the case of TP53.

BACKGROUND: Much research suggests that TP53 mutations have prognostic importance and sometimes are a significant factor in clinical oncology. A considerable effort has been made to develop fast and inexpensive methods for TP53 mutations detection. METHODS: On the basis of describing the role of TP53 as tumor suppressor gene and TP53 mutation spectrum, the authors discuss conventional methods and new technologies for TP53 mutations detection. This discussion is supported by more recent publications in the field of both molecular genetics and analysis technologies. RESULTS: Biosensors and gene chips are of considerable recent interest, due to their tremendous promise for obtaining sequence-specific information in a faster, simpler and cheaper manner compared to traditional methods. CONCLUSIONS: New methods such as biosensors and gene chips appear promising as analytical methods of detecting mutations.

Biomarkers, Tumor↗

PubMed2006

Linking TP53 codon 72 and P21 nt590 genotypes to the development of cervical and ovarian cancer.

TP53 and its downstream effector gene P21 are two important genes in cell cycle regulation. Genetic alterations on p53 and attenuation of p21 expression result in progression through cell cycle G1 checkpoint, which can lead to cancer development. We analysed the frequency of TP53 codon 72 and 3'UTR P21 polymorphisms in 681 blood samples from 371 cervical cancer patients, 122 ovarian cancer patients and 188 healthy controls using AS-PCR and PCR-RFLP. Approximately twofold increased risk of ovarian cancer (OC) was observed for TP53 Pro carriers (P = 0.038), with a significantly higher risk for advanced OC (P = 0.018). Furthermore, among the P21 CC genotypes, TP53 P allele was also associated with a twofold increased risk of OC (P = 0.014) and to a threefold increased risk for advanced OC (P = 0.003) with an attributable proportion of 44.2%. These results were confirmed in an age-adjusted logistic regression analysis. No association was found between these polymorphisms and cervical cancer. Our results suggest that the TP53 codon 72 genotypes may be considered as a molecular marker, contributing to a genetic profile for ovarian cancer in women.

Case-Control Studies↗

PubMed2007

Germline mutations of TP53 and BRCA2 genes in breast cancer/sarcoma families.

The genetic aetiology of familial aggregations of breast cancer and sarcomas has been elucidated only in part. In this study, 23 unrelated individuals from families with one case of sarcoma and at least one case of breast cancer were screened for mutations in the TP53, BRCA1 and BRCA2 genes. Families were classified according to their conformity to the criteria defining the Li-Fraumeni syndrome (LFS), Li-Fraumeni-like (LFL) syndrome and hereditary breast/ovarian cancer (HBOC). Germline TP53 mutations were identified in three instances (13%), including one LFS and two LFL families, while none of the non-LFS/non-LFL families had a TP53 mutation. Three cases (13%), including one with a TP53 mutation, carried BRCA2 mutations. Of these, two were observed in LFL/HBOC families and the other one in a non-LFS/non-LFL/HBOC family, while none of the non-HBOC families tested positive. These findings suggest that the screening of BRCA2, in addition to TP53, may be appropriate for the molecular characterisation of breast cancer/sarcoma families, with practical implications for counselling and clinical management.

Breast Neoplasms↗

PubMed2006

Elevated risk of squamous-cell carcinoma of the lung in heavy smokers carrying the variant alleles of the TP53 Arg72Pro and p21 Ser31Arg polymorphisms.

Alterations in cell cycle regulation and apoptosis leading to malignant transformation could be caused by common genetic variants in tumor suppressor genes. The effects of the TP53 polymorphism Arg72Pro on lung cancer risk have been investigated in numerous studies with, however, conflicting results. In many studies, important risk modifiers such as smoking or tumor histology were not taken into account. We therefore investigated the combined effects of polymorphisms in TP53 (Arg72Pro) and p21/CDKN1A (Ser31Arg) and smoking on lung cancer risk. Our case-control study consisted of 405 patients with lung cancer, mainly squamous-cell carcinoma (185) and adenocarcinoma (177) and 404 unmatched tumor-free hospital controls. Multivariate regression analysis showed a moderate but statistically significant risk of lung cancer overall and especially of squamous-cell carcinoma (OR, 1.65; CI, 1.10-2.47) for TP53 72Pro allele carriers. The risk was markedly increased in heavy smokers (>20 pack-years) with squamous-cell carcinoma (OR, 2.80 in patients homozygous for 72Pro; CI, 1.19-6.58), but not in light smokers (<or=20 pack-years). The results for the p21 Ser31Arg polymorphism suggested that 31Ser is a moderate-risk allele for squamous-cell carcinoma. Analysis of the combined effects of the two polymorphisms revealed a higher OR for TP53 72Pro carriers homozygous for p21 31Ser than for 72Pro carriers in general; this effect being most pronounced in heavy smokers with squamous-cell carcinoma (OR, 3.84; CI, 1.46-10.1). Our data indicate that the TP53 Arg72Pro polymorphism increases the risk for squamous-cell carcinoma mainly in heavy smokers. The observed interaction with smoking is biologically plausible as, for the 72Pro p53 variant, decreased apoptosis and extended G1 cell cycle arrest is reported after carcinogen exposure. Nevertheless, confirmation by further molecular and epidemiological studies is warranted.

Adenocarcinoma↗

PubMed2005

TP53 mutations as biomarkers for cancer epidemiology in Latin America: current knowledge and perspectives.

Due to particular social and economical development, and to the impact of globalization of lifestyles, Latin America shows a superposition of cancers that are frequent in low resource countries (gastric, oesophageal squamous cell and cervical cancers) and high resource countries (cancers of breast, colon and rectum, lung and prostate). Latin America thus offers opportunities for investigating the impact on changing lifestyle patterns on the occurrence of cancer. At the molecular level, mutations in the tumor suppressor gene TP53 are common in many cancers and their distribution can be informative of the nature of the mutagenic mechanisms, thus giving clues to cancer etiology and molecular pathogenesis. However most of the data available are derived from studies in industrialized countries. In this review, we discuss current trends on cancer occurrence in Latin American countries, and we review the literature available on TP53 mutations and polymorphisms in patients from Latin America. Overall, a total of 285 mutations have been described in 1213 patients in 20 publications, representing 1.5% of the total number of mutations reported world-wide. Except for hematological cancers, TP53 mutation frequencies are similar to those reported in other regions of the world. The only tumor site presenting significant differences in mutation pattern as compared to other parts of the world is colon and rectum. However, this difference is based on a single study with 35 patients. Recently, a characteristic TP53 mutation at codon 337 (R337H) has been identified in the germline of children with adrenocortical carcinoma in Southern Brazil. Further and better focused analyses of TP53 mutation patterns in the context of epidemiological studies, should help to improve our understanding of cancer etiology in order to develop appropriate health policies and public health programs in Latin America.

Adult↗

PubMed2005

Human p53 tumor suppressor gene (TP53) and schizophrenia: case-control and family studies.

The human p53 tumor suppressor gene (TP53) is considered as a candidate susceptibility gene for schizophrenia because of its functions in neurodevelopment. To test for an association between TP53 and schizophrenia, both the case-control study and the transmission disequilibrium test (TDT) were performed on genotype data from eight polymorphisms in TP53. Our samples included 286 Toronto schizophrenia cases and 264 controls, and 163 Portuguese nuclear families. In the Toronto case-control study significant differences of allele frequencies of the CAA Ins/Del (p=0.027) and the 16bp Ins/Del (p=0.022) were detected. In TDT analysis we found significant differences for transmission of the CAA Ins/Del (p=0.017) in Portuguese schizophrenia families. Haplotype analysis also showed a significant association between TP53 and schizophrenia. These results provide further evidence that TP53 may play a role in the pathogenesis of schizophrenia.

Brain Chemistry↗

PubMed1996

Prognostic value of TP53 and K-ras-2 mutational analysis in stage III carcinoma of the colon.

BACKGROUND: Genetic mutations involving oncogenes and tumor-suppressor genes occur in carcinogenesis, and may affect biologic behavior of neoplasms. In this study, we analyzed the prognostic value of mutational analysis in colon carcinoma. PATIENTS AND METHODS: Archival pathology specimens from 70 consecutive patients, resected for stage III colon carcinoma, were analyzed for point mutations by amplification and direct sequencing of exons from the K-ras-2 and the TP53 genes (topographic genotyping). Mutations were compared with adverse histopathologic features (poor differentiation, vascular and lymphatic invasion, mucin production) as prognostic markers. RESULTS: Five-year survival was 75% in patients with nonmutated lesions, significantly lower (21%) with TP53 mutations (P = 0.01), and intermediate with K-ras-2 only (45%) or both K-ras-2 and TP53 mutations (36%). A TP53 mutation carried the highest relative risk of death (2.39; 95% confidence interval, 1.29 to 4.42; P = 0.006). There was an additive effect on the risk of death between TP53 mutations and adverse histopathologic features. CONCLUSIONS: The information derived from mutational analysis is creating new prognostic variables that may play a role in the choice of therapy for colorectal carcinoma.

Aged↗

PubMed1999

Mucinous carcinoma of the colon in a 16-year-old Turkish boy with Bloom syndrome: cytogenetic, histopathologic, TP53 gene and protein expression studies.

A 17-year-old Turkish boy with Bloom syndrome (BS) developed mucinous carcinoma of the transverse colon. He was followed from 2 to 17 years of age. Increased sister chromatid exchanges (SCE) were observed, and he was diagnosed with BS at the age of 7. Sun-sensitive skin lesions were examined by skin biopsy, and histopathological studies of these lesions were done. During the follow-up period, an intraabdominal mass at the transverse colon was found, and mucinous carcinoma of colon was diagnosed at the age of 16. We examined TP53 protein expression from paraffin-embedded colon tissue of the patient with an immunohistochemical method. Polymerase chain reaction products of exons 4-9 of the TP53 gene were examined by SSCP. No evidence of overexpression of TP53 protein or mutations of the TP53 gene was observed. The patient in this report is the first case with a mucinous carcinoma of colon diagnosed at an early age in the Bloom Syndrome Registry. Based on our results, carcinoma of the colon in BS patient may occur earlier than 35 years of age and the TP53 gene may not be directly related to carcinoma in Bloom syndrome.

Adenocarcinoma, Mucinous↗

PubMed1999

Is TP53 dysfunction required for BRCA1-associated carcinogenesis?

The identification of the breast/ovarian susceptibility genes, BRCA1 and BRCA2 was an important advancement in the field of breast and ovarian cancer research. About 40-50% of site specific hereditary breast cancers and up to 80% of hereditary breast-ovarian cancers result from mutations in the BRCA1 gene. Although BRCA1 mediates multiple functions in the cell, including a role in DNA damage repair and gene transcription, the role of BRCA1 has not completely been elucidated yet. It has been suggested that mutational inactivation of TP53 may be required for BRCA1-associated tumorigenesis. Several studies have shown that TP53 is more frequently inactivated in BRCA1-associated tumors than in sporadic breast or ovarian cancer. Up to 90% of BRCA1-associated tumors harbor either a TP53 mutation and/or TP53 protein accumulation. The remaining tumors may well have other alterations affecting the cell cycle checkpoint. Loss of this checkpoint may be obligatory for BRCA1-tumorigenesis. In this review, we discuss recent advances in BRCA1-research and stress the pivotal role TP53 may play in BRCA1-associated carcinogenesis.

BRCA2 Protein↗

PubMed2003

Detection of the human papillomavirus and analysis of the TP53 polymorphism of exon 4 at codon 72 in penile squamous cell carcinomas.

Human papillomaviruses (HPV) are thought to be involved in penile squamous cell carcinomas (SCC). A common polymorphism at codon 72 of exon 4 encoding either arginine (Arg) or proline (Pro) has been shown to affect HPV-mediated degradation of p53 in vitro, and may represent a risk factor for HPV-induced carcinogenesis. The presence of HPV DNA as well as the TP53 polymorphism at codon 72 of exon 4 were investigated in a series of 45 penile SCC. HPV detection and typing were carried out by polymerase chain reaction (PCR) with generic primers (MY09-MY11 and FAP59-FAP64), and type-specific DNA probes. TP53 polymorphism was further investigated using Denaturing Gradient Gel Electrophoresis (DGGE). HPV DNA was detected in 67% of penile SCC and 32% of benign lesions (BL) (P<0.05). Among the TP53 amplified samples, the rate of Arg homozygosity in penile SCC was 61% compared with 68% in BL (non-significant (NS)). Our results demonstrate a strong association between penile SCC and the presence of HPV DNA. The TP53 Arg/Arg genotype does not appear to represent a risk factor for the development of genital SCC in men, and no correlation was found between the TP53 polymorphism at codon 72 and the presence of HPV DNA.

Adult↗

PubMed1996

Demonstration of p53 protein and TP53 gene mutations in oligodendrogliomas.

Paraffin embedded tissue of 84 oligodendrogliomas (63 primary tumours, 21 recurrences), 21 glioblastomas with oligodendroglial growth pattern (15 primaries, 6 recurrences) and 17 mixed gliomas was investigated for the presence of mutations in exons 5-9 by means of single stranded conformation polymorphism (SCCP), temperature gradient gel electrophoresis (TGGE) and direct DNA sequencing. In parallel, p53 protein accumulation was determined by means of immunohistochemistry. The percentage of mutations was found to be higher than previously reported (6 of 44 grade II oligodendrogliomas, 4 of 19 grade III oligodendrogliomas, 4 of 15 glioblastomas). In 4 cases, the mutations lead to distinct changes in the primary or secondary structure of the protein (cysteine-->tyrosine, proline-->leucine) and were associated with marked accumulation of p53 protein. A significant correlation between p53 protein accumulation and TP53 gene aberrations was found (P < 0.001), although p53 protein accumulation was detected more often than TP53 gene anomalies, indicating that factors other than TP53 gene mutation may also lead to a p53 protein accumulation in the tumour cells. A significant correlation was found for p53 protein accumulation and tumour grade but not TP53 gene mutations. In conclusion, evaluation of p53 protein accumulation reflected the clinical course of oligodendrogliomas better than the mere presence of TP53 gene mutations.

Adult↗

PubMed1996

Polymorphisms in P21CIP1/WAF1 are not correlated with TP53 status in sporadic ovarian tumours.

In breast cancers and sarcomas, a variant polymorphism in the cell cycle inhibitor P21CIP1/WAF1 is under-represented in those individuals whose tumours contain mutated TP53. The aim of this study was to determine whether this variant polymorphism was also under-represented in those with ovarian carcinoma and TP53 mutations. We studied lymphocyte DNA from 104 women with ovarian carcinoma, 15 with borderline tumours and 16 with benign tumours, using a previously-reported PCR-RFLP technique. 96 of the ovarian carcinoma cases had been previously examined for mutations in TP53 and/or for overexpression of the TP53 protein. The variant allele was seen in 11 out of 104 women (10.6%) with ovarian carcinoma. There was no significant difference in the distribution of the variant allele in the women whose tumours had (7/47) or did not have (4/49) TP53 mutations (P = 0.523). It does not appear that the presence of this variant allele of P21CIP1/WAF1 has any aetiological role in ovarian carcinomas. Studies in other tumours support this finding.

Alleles↗

PubMed1999

TP53 gene mutation status in pretreatment biopsies of oesophageal adenocarcinoma has no prognostic value.

Identification of markers which help to predict response to treatment and overall survival at the time of diagnosis would assist in the management of patients with oesophageal adenocarcinoma. In the present study we investigated the prognostic significance of mutations to the TP53 tumour suppressor gene in a large, consecutive series of oesophageal adenocarcinomas. The incidence of TP53 mutation determined by molecular analysis of endoscopic biopsy specimens was 36% (49/135). No statistically significant difference was observed in patient survival according to the TP53 status of the tumour biopsy. The median survival time for patients with mutation was 12 +/- 1 months compared with 14 +/- 2 months for patients with TP53. These results demonstrate that mutation of the TP53 gene is not a useful predictive marker for patient survival in oesophageal adenocarcinoma.

Adenocarcinoma↗

PubMed2002

A novel, de novo germline TP53 mutation in a rare presentation of the Li-Fraumeni syndrome in the maxilla.

We undertook the genetic analysis of a classic Li-Fraumeni syndrome (LFS) family with clustering of primary tumours including two maxillary sarcomas, a rare LFS site of tumour occurrence. Our aim was to investigate the presence of a specific type of TP53 mutation that could be associated with this unusual predilection of site for cancer occurrence. Mutational screening of the coding region of TP53 revealed an A>T transversion in codon 144 of exon 5 (CAG>CTG, Gln>Leu) in the germline of one of the three affected members, with loss of heterozygosity (LOH) in the tumour tissue. All other affected members were negative for germline or somatic TP53 mutations. TP53 immunohistochemistry was uninformative. The mutation we report is a de novo constitutional TP53 mutation that has not been previously described in the literature. It could explain the more burdened phenotype of the affected patient (died at 21 months). Alternative mechanisms to explain the overall family phenotype are discussed.

Adolescent↗

PubMed2001

Biophenotypes and survival of BRCA1 and TP53 deleted breast cancer in young women.

The aim of this study was to examine the loss of heterozygosity (LOH) of BRCA1 (17q21) and TP53 (17p13.1) in early-onset breast cancer patients; to correlate biopathological characteristics with molecular alterations; and to investigate the survival of LOH-related cancers. BRCA1 and TP53 LOH were evaluated in 78 early-onset breast cancers (< or = 40 years, Group 1) and 80 patients with age > 55 years (Group 2). Cases were characterized for multiple biological markers (ER, PR, proliferation index (PI), NEU and p53). LOH was carried out on microdissected paraffin embedded tissues; microsatellites D17S855 (BRCA1) and D17S786 (TP53) were amplified by fluorescent PCR and analyzed by an automated DNA sequencer. Early-onset breast cancers showed a higher frequency of ductal histotype (89.7% vs. 56.3% p < 0.001), node-positive (53.8% vs. 38.7%), larger size (p = 0.017), higher mitotic rate (p = 0.025), higher nuclear and final grade (p = 0.01 and p = 0.001, respectively). D17S855 LOH was 32.8% in group 1 vs. 21% in group 2; D17S786 LOH was 50.7% vs. 31.3% (p = 0.03), respectively. BRCA1 LOH was correlated with higher PI (p = 0.032) and higher p53 expression (p < 0.001) in group 1 and with higher NEU expression (p = 0.028) in group 2. TP53 LOH was correlated with p53 overexpression (p = 0.03) in group 1. A worse clinical outcome in early-onset LOH related cancers emerged from follow-up data: TP53 and BRCA1 LOH were associated with a shorter relapse free interval (RFI) (p = 0.03) and a poorer overall survival (OS) (p = 0.04), respectively. This study underlines different biological profiles in the two age groups investigated, probably reflecting different mechanisms of carcinogenesis. In accordance with adverse histopathological features in early-onset patients, LOH-related cancers have an unfavorable prognosis.

Adult↗

PubMed1993

Prognostic significance of TP53 alterations in breast carcinoma.

Constant denaturant gel electrophoresis (CDGE) was used to screen 179 breast carcinomas for mutations in the conserved regions of the TP53 gene (exons 5 through 8). Mutations were found in 35 of 163 primary tumours (21%) and in 5 of 16 metastases (31%) and resided predominantly in exon 7. The majority of the mutations were G:C-->A:T transitions. Immunohistochemistry demonstrated nuclear accumulation of p53 protein in 35 of 162 primary tumours (22%) and in four of 15 metastases (27%). TP53 mutation was strongly associated with nuclear accumulation of p53 protein. In total 42 of 163 primary tumours (26%) and 5 of 16 metastases (31%) were demonstrated to contain TP53 alterations (mutation and/or nuclear protein accumulation). TP53 alteration in primary tumour was significantly associated with the following parameters: positive node status, T status > 1, negative oestrogen receptor status, negative progesterone receptor status, presence of ERBB2 gene amplification, and invasive ductal histology. Furthermore, there were statistically significant associations, independent of other prognostic factors, between TP53 alterations in primary tumour and disease-free and overall survival.

Adult↗

PubMed1995

MDM2 overexpression is rare in ovarian carcinoma irrespective of TP53 mutation status.

Somatic mutations in TP53 are seen in many human cancers. In addition, the protein product of the wild-type TP53 can be sequestered by the protein MDM2 (murine double minute 2). This protein is commonly overexpressed in human sarcomas and gliomas, usually as a result of gene amplification. In this study, 43 ovarian carcinomas (OCs) were analysed for aberrations in the TP53 gene by immunohistochemistry (IHC), loss of heterozygosity (LOH) or mutation analysis. The MDM2 gene and its product was studied by Southern blotting and IHC. Over 50% of the OCs studied showed mutations in TP53 by either direct sequencing (19/36, 53%), positive IHC (23,43, 53%) or both, whereas 0/32 had amplification of MDM2 and only 1/37 tumours had positive IHC using the anti-MDM2 antibody IF-2. The solitary example of positive IHC in this series was seen in a mixed müllerian tumour with sarcomatous differentiation and was not accompanied by MDM2 DNA amplification. These results support previous data showing that around 50% of OCs have mutations in TP53 and in addition, suggest that MDM2 is not amplified in OC, but the presence of sarcomatous features in mixed müllerian tumours may result in positive immunohistochemistry with IF-2.

Chromosome Deletion↗