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M Hollstein

Publications and source records attributed to M Hollstein.

At least 37 records · Page 2Linked to original sources
PubMed1997

Inactivation of the p53 protein in cell lines derived from human esophageal cancers.

Alteration of the p53 gene is thought to be important in the early stages of human esophageal cancers, but how this confers a selective advantage to esophageal cancer cells is unknown. In this report, we analyzed 9 cell lines derived from human esophageal cancers (TE-1, TE-3, TE-6, TE-7, TE-9, TE-10, TE-11, TE-13 and TE-15) for mutations in the p53 sequence, p53 protein expression and p53 protein DNA-binding activity. The cell lines could be grouped in 3 categories, including (1) cell lines with mis-sense mutations in the coding sequence and accumulation of mutant proteins (TE-1, TE-6, TE-10 and TE-11); (2) cell lines expressing truncated forms of p53 as a result of frameshift (TE-9) or splice-site (TE-15) mutations; and (3) cell lines with wild-type p53 sequences but with impaired expression of p53 mRNA and protein, suggesting that p53 is inactivated by transcriptional repression (TE-3, TE-7 and TE-13). With the exception of TE-1, none of the cell lines exhibited p53-DNA-binding activity. In TE-1, a mutation at codon 272 (methionine to valine) generated a protein that retains basal DNA-binding activity, but that was not activated in response to DNA damage, suggesting that this mutation prevented p53 induction by genotoxic stress. Thus, p53 activity was impaired in all esophageal cell lines, including those containing wild-type p53 sequences.

Base Sequence↗
PubMed1997

Database of p53 gene somatic mutations in human tumors and cell lines: updated compilation and future prospects.

In recent years, there has been an exponential increase in the number of p53 mutations identified in human cancers. The p53 mutation database consists of a list of point mutations in thep53 gene of human tumors and cell lines, compiled from the published literature and made available through electronic media. The database is now maintained at the International Agency for Research on Cancer (IARC) and is updated twice a year. The current version contains records on 5091 published mutations and is expected to surpass the 6000 mark in the January 1997 release. The database is available in various formats through the European Bioinformatics Institute (EBI) ftp server at: ftp://ftp.ebi.ac.uk/pub/databases/p53/ or by request from IARC (p53database@iarc.fr) and will be searchable through the SRS system in the near future. This report provides a description of the criteria for inclusion of data and of the current formats, a summary of the relevance ofp53 mutation analysis to clinical and biological questions, and a brief discussion of the prospects for future developments.

Databases, Factual↗
PubMed1997

p53 gene mutation analysis in tumors of patients exposed to alpha-particles.

The p53 gene was examined for point mutations in archived, alpha-radiation-associated lung and liver cancers. Lung tumors of 50 uranium miners in Germany were screened by restriction fragment length analysis for the putative hotspot mutation at codon 249 (Arg-->Met) previously detected in a significant fraction of miners from the Colorado Plateau, USA. This mutation has been proposed as a marker of radon exposure. None of the tumors we examined harbored the hotspot mutation. Five of the 50 tumors, however, did indeed harbor exon 7 mutations, as determined by subsequent mutation analysis of exon 7. These mutations were dispersed among various codons and may be attributable to heavy tobacco smoking in this cohort. In support of this interpretation, we found no mutations in exons 5-8 of the p53 gene in 13 iatrogenic liver cancers induced by injection of Thorotrast, an alpha-emitting radiocontrast agent. We propose that if the p53 tumor suppressor gene is a target for the carcinogenic action of alpha-particle radiation, loss of suppressor function may occur preferentially by mechanisms such as intrachromosomal deletions, rather than by base substitution mutations.

Aged↗
PubMed1996

Genetic alterations in esophageal cancer and their relevance to etiology and pathogenesis: a review.

Cancer of the esophagus exists in 2 main forms with different etiological and pathological characteristics-squamous cell carcinoma (SCC) and adenocarcinoma (ADC). This review focuses on the occurrence of genetic alterations in SSC and ADC of the esophagus and on their possible implications for the elucidation of the etiology and pathogenesis of these cancers. The most common alterations found in esophageal cancers include allelic losses at chromosomes 3p, 5q, 9p, 9q, 13q, 17p, 17q and 18q, as well as mutations of p53 (mostly missense), Rb (deletions), cyclin DI (amplifications) and c-myc (amplifications). The sequence of occurrence of these alterations with respect to histopathological tumor progression is discussed. Our findings underscore the different etiology and pathogenesis of SCC vs. ADC and suggest that the genetic alterations observed may represent molecular fingerprints of critical risk involved in the development of these 2 cancers.

Adenocarcinoma↗
PubMed1996

Low frequency of p16/CDKN2 gene mutations in esophageal carcinomas.

Mutational analysis of the p16/CDKN2 gene was conducted by direct sequencing of the whole coding sequence (exons 1-3 and flanking splicing sites) in 21 esophageal squamous-cell carcinomas and 3 adenocarcinomas from a high-incidence area of Italy. Two inactivating mutations were found in exon 1 of the gene (both in squamous-cell carcinoma), whereas no mutations were detected in exon 2, where most of the sequence changes reported so far have been located, or in exon 3. Southern blot analysis of exon 2 in this set of samples and in a complementary set of 12 tumor samples from France did not show homozygous deletions or detectable gene rearrangements. Thus, p16/CDKN2 gene alterations do not appear to play a major role in the group of patients examined.

Adenocarcinoma↗
PubMed1996

Somatic point mutations in the p53 gene of human tumors and cell lines: updated compilation.

In 1994 we described a list of approximately 2500 point mutations in the p53 gene of human tumors and cell lines which we had compiled from the published literature and made available electronically through the file server at the EMBL Data Library. This database, updated twice a year, now contains records on 4496 published mutations (July 1995 release) and can be obtained from the EMBL Outstation-the European Bioinformatics Institute (EBI) through the network or on CD-ROM. This report describes the criteria for inclusion of data in this database, a description of the current format and a brief discussion of the current relevance of p53 mutation analysis to clinical and biological questions.

CD-ROM↗
PubMed1996

Discrepancy between cytotoxicity, platinum accumulation, and DNA platination in MCF-7 breast cancer cells treated with diaqua (1,2-diphenylethylenediamine) platinum (II) sulfates and cisplatin.

Cisplatin (cis), raceme-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine] platinum(II) sulfate (r-4F-PtSO4), meso-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) sulfate (m-4F-PtSO4), and meso-diaqua[1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] platinum(II) sulfate (m-2,6Cl2-4OH-PtSO4) were compared with regard to their growth inhibitory effect on MCF-7 breast cancer cells. At concentrations of 5 microM, cis, r-4F-PtSO4, and m-4F-PtSO4 were essentially equiactive, whereas m-2,6Cl2-4OH-PtSO4 was ineffective. Platinum measurements by neutron activation analysis showed that a 24-h treatment of the MCF-7 cells with r-4F-PtSO4 and m-4F-PtSO4 caused a 22.3- and 10.3-fold accumulation, respectively, whereas the accumulation factors for cis (2.55) and m-2,6Cl2-4OH-PtSO4 (1.83) were very low. The comparison of DNA-associated platinum revealed a similar tendency. After 24 h of drug exposure, the base pair/ platinum ratios were: 2.1.10(4) for r-4F-PtSO4, 3.7.10(4) for m-4F-PtSO4, 6.1.10(4) for cisplatin, and 8.1. 10(4) for m-2,6Cl2-4OH-PtSO4. Thus, the grade of cytotoxicity was correlated neither with the extent of cellular platinum enrichment nor with the degree of genomic DNA platination.

Antineoplastic Agents↗
PubMed1996

Clinical implications of the p53 gene.

The capacity for malignant growth is acquired by the stepwise accumulation of defects in specific genes regulating cell growth and tissue homeostasis. Although several hundred genes are known to control growth, molecular genetic studies in cancer show that few of these are consistently involved in the natural history of human cancer, and those typically in only certain types of malignancy. Prospects for development of molecular-based diagnostic and therapeutic strategies with widespread application did not look promising, until it was realized that the p53 tumor suppressor gene was defective in approximately half of all malignancies. This discovery generated research efforts of unparalleled intensity to determine how p53 functions at the molecular level, and how to apply this knowledge to clinical ends.

Apoptosis↗
PubMed1996

Molecular etiopathogenesis of esophageal cancers.

The occurrence and the relevance in squamous cell carcinomas (SCC) and Barrett's adenocarcinomas (ADC) of genetic alterations, namely mutations in the p53 gene, allelic loss at various chromosomal loci and altered expression of genes involved in the regulation of cell proliferation, are described and discussed with reference to the etiology and pathogenesis of esophageal cancers. Mutations in the p53 gene occur in both SSC and ADC with a frequency of up to approximately 80%, although with a strikingly different pattern of mutations. In ADC, a very high frequency of G > A transitions at CpG dinucleotides was observed, whereas in SCC, mutations at A:T base pairs was comparatively high. In addition, in SCC, the frequency of p53 mutations was related to tobacco smoking. These data therefore indicated that such mutation analysis could provide valuable insight into the etiology of this cancer. It is also apparent that the genetic alterations involving genes other than p53 are also present in the natural history of esophageal cancer. The significance of these genetic changes as well as alterations of expression of cell cycle regulatory genes in esophageal carcinogenesis is briefly discussed.

Adenocarcinoma↗
PubMed1995

Anti-p53 antibodies in sera of workers occupationally exposed to vinyl chloride.

BACKGROUND: The p53 tumor suppressor gene (also known as TP53) is often mutated in a wide variety of cancers, including angiosarcoma of the liver (ASL). Anti-p53 antibodies have been detected in the sera of patients with leukemia, childhood lymphoma, or cancers such as those of the breast, lung, colon, esophagus, and liver (hepatocellular carcinoma). PURPOSE: The objective of this study was to determine the prevalence and time of appearance of serum anti-p53 antibodies during the pathogenesis of ASL associated with occupational exposure to vinyl chloride. METHODS: Enzyme-linked immunoassay (EIA) was used to detect anti-p53 antibodies in 148 serum samples from 92 individuals occupationally exposed (in France or in Kentucky) to vinyl chloride; 15 of these individuals (six from France and nine from Kentucky) had ASL. A subset of coded EIA-positive and EIA-negative sera was further analyzed for anti-p53 antibodies by immunoblotting and immunoprecipitation. Nucleotide sequence analysis of exons 5-8 of the p53 gene was conducted on ASL DNA from six patients. We tested sera from 31 men who had no occupational exposure to vinyl chloride; they made up the control group. Statistical analyses were done using the Kruskal-Wallis chi-squared approximation and the Wilcoxon two-sample test for normal approximation. All P values result from two-sided tests. RESULTS: Fourteen serum samples (from nine individuals) were positive in the EIA. Five of the 15 individuals with ASL were positive for anti-p53 antibodies by EIA, immunoblotting, and immunoprecipitation: one individual at 11.3 and 10.8 years before diagnosis, another at 4 months before and shortly after diagnosis, and three when diagnosed or shortly thereafter. Four of the 77 vinyl chloride-exposed workers without diagnosed ASL were positive for anti-p53 antibodies; two of the four had symptoms related to vinyl chloride toxicity. Tumors from three of the six vinyl chloride-exposed workers from which sufficient DNA for analysis was obtained had A:T to T:A missense mutations of the p53 gene. Anti-p53 antibodies were detected in two of these individuals. Among the control group, two of 15 serum samples from 15 lung cancer patients and zero of 15 serum samples from control subjects without cancer had anti-p53 antibodies as substantially lower levels than the nine (10%) of 92 vinyl chloride-exposed workers who were positive for anti-p53 antibodies. CONCLUSIONS AND IMPLICATIONS: Serum anti-p53 antibodies can predate clinical diagnosis of certain tumors, such as ASL, and may be useful in identifying individuals at high cancer risk, such as workers with occupational exposure to vinyl chloride.

Adult↗
PubMed1995

p53 mutations in esophageal tumors from high-incidence areas of China.

Carcinomas of the upper digestive tract (squamous-cell carcinoma of the esophagus, adenocarcinoma of the cardia) from 24 patients residing in Linxian (China) and near-by high-incidence areas were analyzed for mutations in exons 5-8 of the p53 tumor-suppressor gene. Mutations were identified by polymerase chain reaction amplification and direct sequencing in 50% of the specimens. Eleven tumors harbored a single base-pair substitution leading to either an amino-acid substitution (8 tumors) or a chain-termination signal (3 tumors), and one tumor revealed a 15-bp deletion in exon 7 with a silent base substitution adjacent to the deletion site. Mutations occurred in all 4 exons examined, with a preponderance in exon 5. Of the 6 mutations identified among the 14 adenocarcinomas examined, 3 were G to T transversions, a mutation that has thus far been absent from reported mutations in Barrett's esophageal adenocarcinomas and dysplasias from patients residing in Europe and North America.

Adenocarcinoma↗
PubMed1995

Screening for p53 gene mutations in archived tumors of workers occupationally exposed to carcinogens: examples from analysis of bladder tumors.

Point mutations in the p53 tumor suppressor gene are the most common genetic alterations in human cancers. The nature and location of these mutations can be informative in assessing the importance of putative carcinogenic agents. Potential associations between a given carcinogen and a specific mutation pattern can be substantiated when the exposure history of the patients is known. While the past exposure to environmental risk factors is often difficult to determine, documented occupational exposure to carcinogens presents a unique situation for evaluating this approach. Analysis usually involves working with paraffin-embedded tissues, fixed under conditions suboptimal for genetic analysis and stored for many years, since frozen tissues are not available in sufficient numbers. The particular methodological problems encountered with fixed samples are discussed here, using as illustration an ongoing study of oncogene and tumor suppressor gene mutations in archived bladder tumors of workers exposed to aromatic amines and nonexposed patients.

Base Sequence↗
PubMed1994

Mutations in the conserved regions of p53 are infrequent in betel-associated oral cancers from Papua New Guinea.

Seventy-five % of the world's oral cancers arise in developing countries. In high incidence areas of Southeast Asia such as Papua New Guinea (PNG) the major region-specific risk exposure is betel quid chewing. While it has been shown that p53 gene mutations in the conserved midregion (exons 5-9) are a common feature of oral cancers in the developed world, there is no information on this type of genetic lesion in betel quid-associated oral cancers. We examined 50 oral squamous cell carcinomas, 20 from Baltimore, MD and 30 from PNG, for mutations in exons 5-9 of the p53 gene. DNA extracted from frozen biopsies was amplified by polymerase chain reaction, the purified product was sequenced directly, and mutations were confirmed by repeating the entire procedure. Mutations were found in 3 of 30 tumors from PNG (10%), whereas 9 mutations were detected among the 20 tumors (45%) from Baltimore, MD. This difference in frequency is statistically significant (P < 0.01) by chi 2 analysis. Nuclear accumulation of p53 protein, determined by immunohistochemistry with the CM-1 antiserum, was observed in the PNG cases harboring a missense mutation of the p53 gene. In agreement with the low number of PNG cancers with mutations, only 17% of the cases from PNG were immunostain positive. To explore whether less conserved regions of the gene are preferential targets for alterations in this patient group, sequence analysis in tumors from PNG was extended to outlying regions of the gene (all of exons 4 and 10, and splice sites), but mutations in only two additional tumors were identified. The presence of human papillomavirus DNA in PNG cases was examined with a polymerase chain reaction-based procedure, and viral sequences (human papillomavirus strains 11/16) were detected in two tumors. Human papillomavirus-triggered degradation of the tumor suppressor protein is thus unlikely to be a typical pathway to p53 dysfunction in tumors from PNG.

Adult↗
PubMed1994

Geographic variation of p53 mutational profile in nonmalignant human liver.

Fifty-eight percent of hepatocellular carcinomas (HCCs) from Qidong, China, contain an AGG to AGT mutation at codon 249 of the p53 tumor suppressor gene, a mutation that is rarely seen in HCCs from Western countries. The population of Qidong is exposed to high levels of aflatoxin B1 (AFB1), a fungal toxin that has been shown to induce the same mutation in cultured human HCC cells. To investigate the role of AFB1 and of these p53 mutations in hepatocarcinogenesis, normal liver samples from the United States, Thailand, and Qidong (where AFB1 exposures are negligible, low and high, respectively) were examined for p53 mutations. The frequency of the AGG to AGT mutation at codon 249 paralleled the level of AFB1 exposure, which supports the hypothesis that this toxin has a causative--and probably early--role in hepatocarcinogenesis.

Aflatoxin B1↗
PubMed1994

p53 mutations at A:T base pairs in angiosarcomas of vinyl chloride-exposed factory workers.

Mutations in the p53 tumor suppressor gene are commonly found in the major human cancers and the mutational spectrum in some cancer types is consistent with the genotoxic effects of the associated environmental risk factors. Thus far there is little information on p53 mutations in cancers of factory workers with a history of carcinogen exposure in the workplace. Occupational exposure to vinyl chloride causes liver angiosarcomas (ASL) and also increases the risk of several other cancers. Loss of p53 function in osteo- and fibrosarcomas can occur by two different mechanisms, p53 mutation and amplification of the MDM2 gene. We examined tumors from five vinyl chloride-exposed patients, four with ASL and one with hepatocellular carcinoma (HCC), for evidence of MDM2 proto-oncogene amplification or p53 mutation in exons 5-8. Amplification of MDM2 was not found, but in two of the angiosarcomas an A:T to T:A missense mutation was detected. p53 sequence analysis of vinyl chloride associated cancers may provide valuable information on the relationship between carcinogen exposure and DNA damage in cancer-related genes.

Adenine↗