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Base excision repair (BER) and nucleotide excision repair (NER) pathways repair damaged DNA, and polymorphisms in these genes might affect breast cancer susceptibility. We evaluated associations between seven single-nucleotide polymorphisms in four DNA repair genes (ERCC4 rs1799801, XPC rs2227998, rs2228001, rs2228000, OGG1 rs1052133 and XRCC1 rs25487 and rs25486) and breast cancer risk, examining modification by smoking and alcohol consumption, using data from the Western New York Exposures and Breast Cancer Study. Women aged 35–79 years with incident breast cancer (n = 1170) and age- and race-matched controls (n = 2115) were enrolled. Genotyping was performed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Unconditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs). No significant associations were observed in premenopausal women. Among postmenopausal women, rs25487 and rs25486 (OR = 1.24; 95% CI 1.01–1.51 and OR = 1.23; 95% CI 1.01–1.49, respectively, for combined heterozygous and homozygous variant compared with reference) were associated with increased risk of breast cancer. Postmenopausal women carrying the variant allele of the synonymous XPC polymorphism (rs2227998) were also at borderline significantly increased risk (OR = 1.24; 95% CI 1.01–1.52, heterozygous variant compared with reference; OR = 1.22; 95% CI 1.01–1.48, for combined heterozygous and homozygous variant compared with reference). There was no evidence of genotype–smoking and genotype–alcohol consumption interactions for pre- and postmenopausal women. These results indicate that some of the variants in BER and NER genes may influence risk of postmenopausal breast cancer. [ABSTRACT FROM AUTHOR]

Although rodent cells have been immortalized following transfection with a mutant p53 gene, the role of p53 in the immortalization of human cells is unknown. Therefore, human epithelial cell lines were examined for p53 mutations in exons 4–9 which include the evolutionarily conserved regions. A spontaneously immortalized skin keratinocyte cell line, HaCat, and three ras-transfected clones, have a p53 mutational spectrum that is typical of ultraviolet light induced mutations. A normal finite lifespan cell strain (184) and two benzo[a]pyrene immortalized mammary epithelial cell lines derived from 184 (184A1 and 184B5) contain wild type p53 sequences in exons 4–9, although elevated levels of nuclear p53 indicate an alteration in the stability of the normally transient protein. Wild type p53 was found in human bronchial, esophageal and hepatic epithelial cells immortalized by SV40 T antigen gene and human renal epithelial cells immortalized by adenovirus 5. BEAS-2B, an SV40 T antigen immortalized bronchial epithelial cell line and two subclones, have a germline polymorphism at codon 47. Inactivation of p53 by mechanisms such as mutation or complexing with proteins of DNA tumor viruses appears to be important in the immortalization of human epithelial cells. [ABSTRACT FROM PUBLISHER]

DNA isolated from chondrosarcoma cells effectively transformed NIH-3T3 cells and human foreskin fibroblasts. The transfected NIH-3T3 cells, directly implanted three or four passages later, formed progressively growing tumors (≥ 2.0 cm in diameter) subcutaneously in nude mice. No metastasis was evident upon pathological examination of the tumor bearing mice. Transfected human foreskin fibroblasts that exhibited anchorage independent growth formed only small tumors in nude mice (<0.6 cm in diameter). The transfected human cells which exhibited anchorage independent growth reacted with the monoclonal antibody 345.134S, specific for an epitope expressed by human sarcoma cells. The transfected NIH-3T3 cells did not exhibit reactivity with the same monoclonal antibody. Southern blot analysis of the DNA prepared from the transfected NIH-3T3 cells, that developed as a progressively growing tumor in a nude mouse, revealed the presence of human repetitive DNA sequences. [ABSTRACT FROM PUBLISHER]