Browsing by Author "Tomlinson, GE"

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    Analysis of the FHIT gene and FRA3B region in sporadic breast cancer, preneoplastic lesions, and familial breast cancer probands
    (1997) Ahmadian, M; Wistuba, II; Fong, KM; Behrens, C; Kodagoda, DR; Saboorian, MH; Shay, J; Tomlinson, GE; Blum, J; Minna, JD; Gazdar, AF
    The FHIT gene, which spans the FRA3B fragile site at chromosome 3p14.2 is a candidate tumor suppressor gene in breast and other cancers. We investigated FHIT and FRA3B for loss of heterozygosity (LOH); homozygous deletions; abnormal transcripts; and acquired/germ-line point mutations in breast cancer cell lines (n = 32), breast epithelial and stromal cell cultures (n = 18), microdissected invasive (n = 16) and ductal in situ carcinomas (n = 6), and their accompanying normal and abnormal epithelial foci (n = 14). LOH at 3p14.2, especially at FHIT intragenic marker D3S1300, was found in 6 of 16 microdissected invasive tumors and 3 of 6 ductal in situ carcinomas. In accompanying preneoplastic foci, LOH occurred in two of eight intraductal hyperplasias but not in histologically normal ductal epithelium (n = 6). Three of 32 (9%) breast cancer cell lines demonstrated homozygous deletions of FHIT exon 4 (two cases) and exon 5 (one case), which correlated with exon 4-deleted transcripts and loss of the cDNA transcript containing the coding exons 5-9, respectively. Normal mammary cultures and 31 or 32 tumor cell lines (97%) expressed wild-type coding transcripts as well as a minor exon 5-deleted message. Single-strand conformation polymorphism analysis of the coding exons in the 32 tumor and 18 normal breast cell lines and their sequencing revealed four silent polymorphisms and a germ-line histidine triad point mutation (651 G-->T) in a tumor arising in a 70-year-old woman. This mutation was also present in one of her two thus far unaffected daughters. Analysis of additional DNAs from 280 probands of high-risk breast cancer families for other FHIT exon 8 mutations detected an intronic point mutation 13 bases upstream of exon 8. Thus, we have demonstrated relatively early abnormalities of the FHIT/FRA3B region in breast cancer and discovered two rare FHIT germ-line mutations. The expression of a transcript containing the coding exons in nearly all cell lines, including those with germ-line mutations, suggests the possibility that another gene in the FRA3B region may be involved in the pathogenesis of breast cancer.
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    Two identical triplet sisters carrying a germline BRCAI gene mutation acquire very similar breast cancer somatic mutations at multiple other sites throughout the genome
    (WILEY, 2000) Wistuba, II; Tomlinson, GE; Behrens, C; Virmani, A; Geradts, J; Blum, JL; Minna, JD; Gazdar, AF
    Monozygotic twins, each of whom has breast cancer, offer a natural study population for gene-environmental interactions as causation of cancer, because they are genetically identical. If heritable factors play a large role in the origin of a neoplasm, disease concordance should be significant in monozygotic twins. Two monozygotic triplet sisters carrying a germline BRCA1 gene mutation (5382insC) who both developed breast cancer at early ages were studied for loss of heterozygosity (LOH) in their microdissected, paraffin-embedded tumors along with control blood and stromal breast tissue at 19 chromosomal arms using 161 microsatellite markers. Microdissected areas of normal lobular and ductal epithelium and ductal in situ carcinoma were also studied for LOH using a subset of microsatellite markers. The mother's DNA (extracted from peripheral blood lymphocytes) was analyzed to determine the parental allele under LOH in each case. Both tumors demonstrated similar histologic features suggestive of a secretory variant of ductal carcinoma. The tumors from both sisters had similar overall LOH frequency expressed by the fractional allelic loss (FAL) indices (0.56 vs, 0.60) and demonstrated concordance for loss or retention at 82 of 97 informative markers (85% correlation). In addition, detailed mapping analysis of several chromosomal arms revealed that identical breakpoints were detected in both tumors at several chromosome regions. Finally, in both sisters' tumors, when a chromosome exhibited allelic loss, all of the markers exhibited LOH of the same parental allele even when there were intervening regions of retention of heterozygosity, In contrast, 17 archival sporadic breast carcinomas demonstrated a wide range of FAL indexes and highly individual patterns of LOH. Our findings support the hypothesis that inherited factors play a role in the development of the multiple somatic deletions occurring in breast carcinomas. Whether one of these factors is the mutant BRCA1 allele or some other gene(s) remains to be determined. (C) 2000 Wiley-Liss, Inc.