Search

Background: The del1518 (rs3730485) polymorphism is an in/del variant in the MDM2 promoter P1. The variant is in complete linkage disequilibrium with MDM2 SNP309 (rs2279744) and has previously been found associated with an increased risk of colon cancer. In this study we assessed the impact of MDM2 del1518 on risk of ovarian and endometrial cancer.Methods: Here, we genotyped del1518 in two large hospital-based series of patients diagnosed with ovarian (n = 1,385) or endometrial (n = 1,404) cancer and performed risk estimations as compared to the genotype distribution among 1,872 healthy female controls.Results: In overall analysis we observed no association between del1518 and risk of either ovarian or endometrial cancer. However, stratifying according to SNP309 status, we found the del1518 variant to be associated with a reduced risk of endometrial cancer among individuals carrying the SNP309TT genotype both in the dominant (OR = 0.64; 95% CI = 0.45 - 0.90) and the recessive model (OR = 0.80; 95% CI = 0.65 - 1.00). No such association was observed for ovarian cancer risk.Conclusion: We found the MDM2 del1518 del variant to be associated with reduced risk of endometrial cancer among individuals carrying the MDM2 SNP309TT genotype. [ABSTRACT FROM AUTHOR]

Background: While germline CHEK2 mutations have been linked to a moderately elevated cancer risk, to date, a limited number of such mutations have been identified. Recently, we reported a germline nonsense mutation (C283T; R95*), introducing an early stop-codon, in two Norwegian patients diagnosed with locally advanced breast cancer. Both patients were resistant to anthracycline therapy, resembling what has been observed for TP53 mutations. Methods: In the present study, we screened a large population based sample, including 3748 non-cancer individuals and 7081 incident cancer cases (breast cancer, n = 1717; prostate cancer n = 2501, lung cancer n = 1331 and colorectal cancer n = 1532), for the distribution of CHEK2 R95*. Results: We found that 12 individuals (0.11 %) carried the R95* variant: 4 non-cancer individuals (0.11 %), 4 breast cancer cases (0.23 %), and 4 prostate cancer cases (0.16 %). Although the low number of observations precluded formal statistical assessment, our data may indicate an elevated risk for breast (OR: 2.19, 95 % CI: 0.55-8.75) and prostate cancer (OR: 1.5, 95 % CI: 0.36-6.00) associated with CHEK2 R95*. By mining international databanks, we found no individuals carrying the R95* mutation, indicating it to be restricted to the Norwegian population. Conclusion: We provide proof-of-concept that previously unknown CHEK2 germline mutations may be present in certain populations. Notably, germline mutations in tumours are in general missed by contemporary massive parallel sequencing strategies, since tumour mutations are usually filtered against the germline. The fact that the CHEK2 R95* mutation may be associated with resistance to anthracyclines in cancer patients emphasizes its possible clinical importance. [ABSTRACT FROM AUTHOR]

Background. Before the advent of neoadjuvant chemotherapy, radiotherapy and surgery alone were associated with a high risk of uncontrolled locoregional relapses in locally advanced breast cancer (LABC). Material and methods. In the 1990s we initiated two neoadjuvant protocols, where patients with LABC were given either doxorubicin qW or 5-fluorouracil/mitomycin (FUMI) q3W to shrink the tumours prior to mastectomy and postoperative radiotherapy. Previously, we reported TP53 mutation status to predict a poor response to chemotherapy. Here, we present the long-term survival data, with a follow-up of 20 years in the doxorubicin (n = 90) and 15 years in the FUMI trial (n = 34). Results. Patients in the doxorubicin trial with TP53-mutated tumours experienced a shorter recurrence-free (RFS; 14 vs. 83 months, p < 0.001) and overall survival (OS; 35 vs. 90 months, p < 0.001) than patients with TP53 wt tumours. Similarily, TP53 mutations were associated with a shorter OS (22 vs. 80 months, p = 0.03) and a tendency to shorter RFS (17 vs. 33 months, p = 0.06) in patients treated with FUMI. Furthermore, axillary lymph node metastases predicted shorter OS, but only in patients treated with doxorubicin (49 vs. 142 months, p < 0.04). Applying multivariate analysis, TP53 mutations predicted inferior RFS (p < 0.001) as well as OS (p < 0.001), independently of axillary lymph node status. Isolated local recurrences, without simultaneous distant metastases, occurred in seven patients only in the two trials. Interestingly, chest wall radiation fibrosis predicted improved OS (p = 0.004). Conclusion. TP53 inactivating mutations are associated with an inferior long-term prognosis in patients with LABC treated with conventional chemotherapy. [ABSTRACT FROM AUTHOR]

BRCA1 associated tumours are found to express an oestrogen receptor negative “basal epithelial-like” phenotype. In contrast to ER negative tumours in general, such tumours rarely harbour amplification of the HER-2 gene. However, little is known about TOP2A gene amplification status in BRCA1-associated tumours. Such information may be of importance to therapy, as amplification of TOP2A has been associated with dose-dependent sensitivity to anthracycline therapy in breast cancer. We examined 40 breast carcinomas from BRCA1 mutation carriers and 40 sporadic breast carcinomas matched for age, tumour diameter and histological grade for HER-2 and TOP2A amplification status using fluorescence in situ hybridisation (FISH). Co-amplification of TOP2A and HER-2 was found in four of the mutation carriers and in three of the controls. While six tumours in the control group harboured HER-2 amplifications with normal TOP2A, this occurred in three of the BRCA1 associated tumours only. In contrast, three of the BRCA1-associated tumours but none of the controls harboured TOP2A amplification despite normal HER-2 status. Our findings have potential therapeutic implications. HER-2 assessment is routinely used to select breast cancer patients for trastuzumab but also dose-intensive anthracycline therapy. Our data suggest that BRCA1-associated breast cancers also need to be tested for TOP2A amplification. [ABSTRACT FROM AUTHOR]

GATA3 is an essential transcription factor that was first identified as a regulator of immune cell function. In recent microarray analyses of human breast tumors, both normal breast luminal epithelium and estrogen receptor (ESR1)-positive tumors showed high expression of GATA3. We sequenced genomic DNA from 111 breast tumors and three breast-tumor-derived cell lines and identified somatic mutations of GATA3 in five tumors and the MCF-7 cell line. These mutations cluster in the vicinity of the highly conserved second zinc-finger that is required for DNA binding. In addition to these five, we identified using cDNA sequencing a unique mis-splicing variant that caused a frameshift mutation. One of the somatic mutations we identified was identical to a germline GATA3 mutation reported in two kindreds with HDR syndrome/OMIM#146255, which is an autosomal dominant syndrome caused by the haplo-insufficiency of GATA3. The ectopic expression of GATA3 in human 293T cells caused the induction of 73 genes including six cytokeratins, and inhibited cell line doubling times. These data suggest that GATA3 is involved in growth control and the maintenance of the differentiated state in epithelial cells, and that GATA3 variants may contribute to tumorigenesis in ESR1-positive breast tumors.Oncogene (2004) 23, 7669-7678. doi:10.1038/sj.onc.1207966 Published online 13 September 2004 [ABSTRACT FROM AUTHOR]

Background: The role of normal tissue gene promoter methylation in cancer risk is poorly understood.Objective: To assess associations between normal tissue BRCA1 methylation and ovarian cancer risk.Design: 2 case-control (initial and validation) studies.Setting: 2 hospitals in Norway (patients) and a population-based study (control participants).Participants: 934 patients and 1698 control participants in the initial study; 607 patients and 1984 control participants in the validation study.Measurements: All patients had their blood sampled before chemotherapy. White blood cell (WBC) BRCA1 promoter methylation was determined by using methylation-specific quantitative polymerase chain reaction, and the percentage of methylation-positive samples was compared between population control participants and patients with ovarian cancer, including the subgroup with high-grade serous ovarian cancer (HGSOC).Results: In the initial study, BRCA1 methylation was more frequent in patients with ovarian cancer than control participants (6.4% vs. 4.2%; age-adjusted odds ratio [OR], 1.83 [95% CI, 1.27 to 2.63]). Elevated methylation, however, was restricted to patients with HGSOC (9.6%; OR, 2.91 [CI, 1.85 to 4.56]), in contrast to 5.1% and 4.0% of patients with nonserous and low-grade serous ovarian cancer (LGSOC), respectively. These findings were replicated in the validation study (methylation-positive status in 9.1% of patients with HGSOC vs. 4.3% of control participants-OR, 2.22 [CI 1.40 to 3.52]-4.1% of patients with nonserous ovarian cancer, and 2.7% of those with LGSOC). The results were not influenced by tumor burden, storage time, or WBC subfractions. In separate analyses of young women and newborns, BRCA1 methylation was detected in 4.1% (CI, 1.8% to 6.4%) and 7.0% (CI, 5.0% to 9.1%), respectively.Limitations: Patients with ovarian cancer were recruited at the time of diagnosis in a hospital setting.Conclusion: Constitutively normal tissue BRCA1 promoter methylation is positively associated with risk for HGSOC.Primary Funding Source: Norwegian Cancer Society. [ABSTRACT FROM AUTHOR]