Ruggero Montesano

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.

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.

Validation and comparative studies on 180 chemicals with S. typhimurium strains and V79 Chinese hamster cells in the presence of various metabolizing systems

Results from tests on a total of 180 compounds in the Salmonella/microsome assay and its adapted procedures are summarized. The following specific problems were analyzed: the predictive value of the test; frequency distribution of chemicals (classes) according to their mutagenic activity; quantitative relationship between mutagenicity versus electrophilicity versus carcinogenicity of some selected carcinogens; chemicals that are activated into mutagens by human-liver enzymes; compounds that have been tested in the presence of rodent hepatic versus extra-hepatic tissue fractions; and some factors involved in the efficient detection of mutagens in vitro, i.e. the source and concentration of liver microsomal protein required for maximal mutagenic activity. As 34 chemicals have also been tested in microsome- or cell-mediated mutagenicity assays by using V79 Chinese hamster cells, an intercomparison is made of test results obtained in bacterial and mammalian assays.

IARC p53 mutation database: A relational database to compile and analyze p53 mutations in human tumors and cell lines

The tumor suppressor p53 gene is the most frequently mutated gene in human cancer. To date, more than 10,000 mutations have been described in the literature, and these data are available in various electronic formats on the World Wide Web. Here we describe the structure and format of the different p53 datasets maintained and curated at the International Agency for Research on Cancer (IARC) in Lyon, France. These include p53 somatic mutations (more than 10,000 entries), p53 germline mutations (144 entries), and p53 polymorphisms (13 entries), with the somatic mutations organized into a relational database using AccessTM. The main features of these datasets are (1) controlled entry with standardized format and restricted vocabulary, (2) inclusion of annotations on individual characteristics and exposures, and (3) a classification of pathologies based on the International Classification of Diseases for Oncology (ICD‐O). In addition, several interfaces have been developed to analyze the data in order to produce mutation spectra, codon analyses, or visualization of the mutation with the tertiary structure of the protein. All datasets and tools for analysis are available at http://www.iarc.fr/p53/homepage. Hum Mutat 14:1–8, 1999.

Liver-microsome-mediated formation of alkylating agents from vinyl bromide and vinyl chloride.

Abstract When a mixture of vinyl chloride/oxygen or vinyl bromide/air was passed through a mouse-liver microsomal system, volatile alkylating metabolites were trapped by reaction with excess 4-(4-nitrobenzyl)pyridine. The absorption spectra of the adducts, either from vinyl bromide or vinyl chloride, were identical with that obtained by reaction of chloroethylene oxide with 4-(4-nitrobenzyl) pyridine. Chloroethylene oxide decomposes in aqueous solution with a half-life of 1.6 minutes. After reaction of chloroethylene oxide and 2-chloroacetaldehyde with adenosine and Sephadex chromatography the binding products were compared with those formed in the presence of vinyl chloride, mouse-liver microsomes and adenosine. A common product of these reactions was tentatively characterized as 3-β-ribofuranosyl-imidazo-[2,1- i ]purine.

The Gambia Liver Cancer Study: Infection with hepatitis B and C and the risk of hepatocellular carcinoma in West Africa

Hepatocellular carcinoma (HCC) is the most common cancer in The Gambia. Hepatitis B virus (HBV) infection is endemic, with 15% to 20% of the population being chronic carriers, whereas hepatitis C virus (HCV) prevalence is low. We recruited 216 incident cases of HCC and 408 controls from three sites. HBV carriage was present in 61% (129/211) of HCC patients and 16% (64/402) of controls, whereas 19% (36/191) of HCC patients were HCV seropositive compared with 3% (11/382) of controls. HCC patients with HCV were notably older and were more likely to be female than those with HBV. Increased HCC risk was strongly associated with chronic HBV (odds ratio, 16.7; 95% CI, 9.7–28.7), HCV (16.7; 6.9–40.1), and dual infection (35.3; 3.9–323). We interpret the additive nature of risk with coinfection as representative of HBV and HCV acting primarily through shared steps in the multistage process of hepatocarcinogenesis. HCV infection was not observed among younger participants, suggesting a possible cohort effect. Reasons for the striking age and gender differences in HCC associated with HBV compared with HCV are unclear, but transmission patterns and age at exposure may be factors. In conclusion, in a standardized evaluation of well‐characterized study participants from The Gambia, most cases of HCC are attributable to HBV (57%), but HCV adds a significant fraction (20%), especially among older patients and females. If HCV transmission is not perpetuated in future cohorts, focusing available resources on HB vaccination efforts could greatly ameliorate a major cause of cancer death in sub‐Saharan Africa. (HEPATOLOGY 2004;39:211–219.).

Ser-249 p53 mutations in plasma DNA of patients with hepatocellular carcinoma from the Gambia.

Background: A selective mutation, an arginine-to-serine substitution in codon 249, of the p53 gene has been identified as a “hotspot” mutation in hepatocellular carcinoma (HCC). This mutation occurs in populations that are exposed to aflatoxins and have a high prevalence of hepatitis B virus carriers. We evaluated whether this mutation could be detected in cell-free DNA isolated from the plasma of subjects from The Gambia to detect this mutation that is strongly associated with HCC. Methods: Fifty-three patients with HCC, 13 patients with cirrhosis, and 53 control subjects were prospectively recruited from The Gambia. Sixty patients, of non-African origin, with various liver pathologies were also selected from France. DNA was extracted and purified from 200-µL aliquots of plasma. The Ser-249 p53 mutation was detected by restriction endonuclease digestion of polymerase chain reaction products from exon 7 and was confirmed by direct sequencing of the amplified DNA. Results: The Ser-249 p53 mutation was detected in plasma DNA from 19 (36%) of the 53 patients with HCC, two (15%) of the 13 patients with cirrhosis, and three (6%) of the 53 control subjects. This mutation was not detected in any plasma DNA from the European patients. The adjusted odds ratio for having the mutation was 16.4 (95% confidence interval = 3.0‐90.5) for patients with HCC compared with the control subjects. Conclusion: The Ser249 p53 mutation in plasma DNA is strongly associated with HCC in Gambian patients. This mutation was also detected at a much lower prevalence in plasma DNA from Gambian patients with cirrhosis and in Gambian control subjects, findings that may lead to the

Mutagenicity of vinyl chloride, chloroethyleneoxide, chloroacetaldehyde and chloroethanol

Exposure of S. typhimurium strains TA 1530, TA 1535 and G-46 to vinyl chloride increased the number of his+ rev./plate 16, 12 or 5 times over the spontaneous mutation rate. The mutagenic response for TA 1530 strain was enhanced 7, 4 or 5-fold when fortified S-9 liver fractions from humans, rats or mice were added. In TA 1530 strain, chloroacetic acid showed only toxic effects, while chloroacetaldehyde, chloroethanol and chloroethyleneoxide caused a mutagenic response. The latter compound was shown to be a strong alkylating agent.

Hepatitis B vaccination in infancy in The Gambia: protection against carriage at 9 years of age

To estimate the efficacy in The Gambia (West Africa) of infant hepatitis B vaccination against infection and carriage with the virus at the age of 9 years. The HBV status of 9-year old children vaccinated in infancy was compared to that of unvaccinated children of the same age. Eight percent of the vaccinated children had been infected by HBV compared to 50% of the unvaccinated control group; HBV carrier status was 0.6 and 10% respectively, resulting in a vaccine efficacy of 83% against infection and of 95% against chronic carriage. The results show that infant vaccination provides a high level of protection at the age of nine years against both HBV infection and chronic carrier status and no booster dose of vaccine is required in the first decade. These findings support the WHO recommendation for the introduction of HBV vaccination into the Expanded Programme on Immunization in Africa.

249 ser TP53 mutation in plasma DNA, hepatitis B viral infection, and risk of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) from regions with high dietary exposure to aflatoxins and endemic for hepatitis B virus (HBV) often contain a specific mutation at codon 249 in TP53 (249ser; AGG to AGT, Arg to Ser). This mutation is also detectable in circulating cell-free DNA from the plasma of HCC patients and healthy subjects in these regions. We have examined the joint effect of plasma 249ser and HBV infection in a case–control study design involving 348 control, 98 cirrhotic, and 186 HCC participants from The Gambia, West Africa, an area of high HCC incidence. The 249ser mutation was detected in 3.5% of controls, 15.3% of cirrhotics, and 39.8% of HCC cases (adjusted odds ratios (OR): 4.83, (95% confidence interval (CI): 1.71–13.7) for cirrhosis and 20.3 (8.19–50.0) for HCC). HBsAg positivity along with plasma 249ser was observed in 45/183 (24.6%) HCC cases compared to only one (0.3%) control. Risk for HCC was associated with markers of HBV alone (OR: 10.0, 95% CI: 5.16–19.6), 249ser alone (OR: 13.2, 95% CI: 4.99–35.0), and both markers present (OR: 399, 95% CI: 48.6–3270). These results suggest a multiplicative effect on HCC risk resulting from the mutational effect of aflatoxin on TP53, as monitored by detection of plasma 249ser, with concomitant chronic infection with HBV.