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Background/aims: Genetic abnormalities of the p53 gene may play a major role in the carcinogenesis of gastric stump carcinomas (GSC) and intestinal-type primary gastric carcinomas (IPGC). Also, they may modulate P-gp expression producing chemoresistance. The aim of this article is to analyze p53 genetic abnormalities and the influence of p53 gene status on P-gp expression in both types of carcinomas., Methodology: Forty-two paraffin-embedded samples of gastric carcinomas corresponding to 17 GSC and 25 IPGC were studied. P53 genetic abnormalities in exon 5-9 were screened by direct sequencing of PCR products. P53 and P-glycoprotein (P-gp) were assessed by a standard streptavidin-biotin immunoperoxidase method. Anti-p53 DO7 and anti-P-gp C494 were used as primary antibodies., Results: Fourteen p53 mutations were found, 5 in GSC (29%) and 9 in IPGC (36%). Thirteen mutations were base-pair substitutions that produced a change in the amino acid sequence. Eight mutations were located at exon 7 (57%). P53 nuclear immunopositivity was observed in 12 GSC (71%) and 15 IPGC (60%). Only two carcinomas (1 IPGC and 1 GSC) harboring a p53 mutation did not show any p53 expression. All except one of the gastric carcinomas having a p53 mutation showed medium or high P-gp expression. However, there was no difference in P-gp expression between tumors with and without p53 mutation., Conclusions: The p53 genetic alterations found in GSC and IPGC could originate from a similar pathogenetic pathway. No association was demonstrated between p53 gene status and P-gp expression, although most of the carcinomas harboring a p53 mutation showed medium or high P-gp expression.

The frame-shift mutation 1100delC in the cell-cycle-checkpoint kinase 2 gene (CHEK2) has been reported to be a low penetrance breast cancer gene in Northern European populations. However, the variant may be relevant for breast cancer risk in other populations, due to its low prevalence. Recent studies have proposed a role for the mutation in colorectal cancer, finding a strong association between the CHEK21100delC mutation and hereditary breast and colorectal cancer (HBCC). A previous study suggested that the CHEK21100delC variant was not of clinical relevance in Spanish breast/ovarian cancer families. Here, we demonstrate that this genetic variant is not of clinical relevance for HNPCC and HBCC Spanish families.

A new BRCA1 locus product called BRCA1-IRIS has been identified recently. High-risk breast/ovarian families have not been screened for germ-line mutations at the specific BRCA1-IRIS coding sequence, as it was considered merely as part of BRCA1 intron 11. Here we report the first comprehensive screening of germ-line mutations in a cohort of 116 index cases from high-risk breast/ovarian families in which no germ-line mutation was identified in BRCA1 or BRCA2. We did not find germ-line mutations at the specific BRCA1-IRIS coding sequence in any sample. The only heterozygous patter identified by DGGE was caused by a C to A substitution in the non-coding 3' sequence, 123 bases downstream of the BRCA1-IRIS stop codon (IVS11+268C/A). The data indicates that it is probably a neutral change not associated with cancer risk. Our analysis suggests that the role of germ-line mutations at the specific BRCA1-IRIS sequence in breast cancer susceptibility, if any, is marginal and do not explain a significant fraction of high-risk breast/ovarian families, at least in the population analyzed.

Six SNPs have been detected in the DNA repair genes RAD51C and RAD51D, not previously characterized. The novel variant E233G in RAD51D is more highly represented in high-risk, site-specific, familial breast cancer cases that are not associated with the BRCA1/2 genes, with a frequency of 5.74% (n = 174) compared to a control population (n = 567) and another subset of breast cancer patients (n = 765) with a prevalence of around 2% only (comparison to controls, OR = 2.6, 95% CI 1.12-6.03; p < 0.021). We found that the immunohistochemical profile detected in available tumors from these patients differs slightly from those described in non-BRCA1/2 tumors. Finally, the structural prediction of the putative functional consequence of this change indicates that it can diminish protein stability and structure. This suggests a role for E233G as a low-penetrance susceptibility gene in the specific subgroup of high-risk familial breast cancer cases that are not related to BRCA1/2., (Copyright 2004 Wiley-Liss, Inc.)

Searching for low-penetrance genes involved in breast cancer susceptibility has been a field of interest in the last few years. Recently, the CHEK 2 gene, involved in DNA damage and replication checkpoints, has been pointed out as a good candidate; moreover, a specific variant in this gene,1100delC, has been found to increase breast cancer susceptibility among familial breast cancer cases not attributable to mutations in BRCA1 or BRCA2 genes. In our present study, we evaluated the role of the 1100delC variant as a susceptibility allele in breast cancer in the Spanish population. However, our results suggest that this variant is absent or very infrequent in our population, making its screening irrelevant from the practical point of view., (Copyright 2003 Wiley-Liss, Inc.)

We screened index cases from 410 Spanish breast/ovarian cancer families and 214 patients (19 of them males) with breast cancer for germ-line mutations in the BRCA1 and BRCA2 genes, using SSCP, PTT, CSGE, DGGE, and direct sequencing. We identified 60 mutations in BRCA1 and 53 in BRCA2. Of the 53 distinct mutations observed, 11 are novel and 12 have been reported only in Spanish families (41.5%). The prevalence of mutations in this set of families was 26.3%, but the percentage was higher in the families with breast and ovarian cancer (52.1%). The lowest proportion of mutations was found in the site-specific female breast cancer families (15.4%). Of the families with male breast cancer cases, 59.1% presented mutations in the BRCA2 gene. We found a higher frequency of ovarian cancer associated with mutations localized in the 5' end of the BRCA1 gene, but there was no association between the prevalence of this type of cancer and mutations situated in the ovarian cancer cluster region (OCCR) region of exon 11 of the BRCA2 gene. The mutations 187&#95;188delAG, 330A>G, 5236G>A, 5242C>A, and 589&#95;590del (numbered after GenBank U14680) account for 46.6% of BRCA1 detected mutations whereas 3036&#95;3039del, 6857&#95;6858del, 9254&#95;9258del, and 9538&#95;9539del (numbered after GenBank U43746) account for 56.6% of the BRCA2 mutations. The BRCA1 330A>G has a Galician origin (northwest Spain), and BRCA2 6857&#95;6858del and 9254&#95;9258del probably originated in Catalonia (northeast Spain). Knowledge of the spectrum of mutations and their geographical distribution in Spain will allow a more effective detection strategy in countries with large Spanish populations., (Copyright 2003 Wiley-Liss, Inc.)