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Query: UMLS:C0178874 (tumor progression)
 40,807 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sporadic cancers and familial breast cancers are characterized by an increase in genetic instability. Little is known about whether mismatch repair defects accompany this genetic instability. We investigated invasive and/or in situ breast cancers from 30 women with deleterious BRCA1/2 mutations and unclassified variant BRCA1/2 alterations. Forty cases of sporadic breast cancers were also investigated, including 7 medullary carcinomas. Malignant and benign lesions were examined from all cases to better understand tumor progression. Automated immunohistochemistry, with antibodies directed against hMLH1 and hMSH2, was used to screen cases for possible mismatch repair defects. When loss of expression was noted, DNA ploidy was performed by cytomorphometry. DNA, after laser microdissection, was extracted from a majority of familial cases and their corresponding controls, and microsatellite instability analysis was performed. None of the familial or sporadic cases had loss of hMSH2 expression. All but one lesion, a DCIS arising in a deleterious BRCA2 mutation carrier, had loss of hMLH1 expression and a tetraploid profile by image cytomorphometry. There was no MSI in any explored lesions (n = 34), as determined by molecular analysis, including the DCIS with loss of hMLH1 expression. We conclude that DNA mismatch repair defects involving hMLH1 and hMSH2 underexpression are extremely rare events in sporadic and familial breast cancer. Mismatch repair gene mutations may be secondary random events in breast cancer progression.
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PMID:Microsatellite instability in hereditary and sporadic breast cancers. 1452 Jun 95

Breast cancer risk is greatly increased in women who carry mutations in the BRCA1 or BRCA2 genes. Because breast cancer initiation is different between BRCA1/2 mutation carriers and women who do not carry mutations, it is possible that the mechanism of breast cancer progression is also different. Histopathologic and genetic studies have supported this hypothesis. To test this hypothesis further, we utilized a large cohort of women who underwent therapeutic mastectomy (TM) and contralateral prophylactic mastectomy (PM). From this cohort, we developed case groups of women with a family history of breast cancer with BRCA1/2 deleterious mutations, with unclassified variant alterations, and with no detected mutation and matched these cases with sporadic controls from the same TM and PM cohort. Fluorescence in situ hybridization was performed on paraffin sections by use of dual-color probes for ERBB2/CEP17, MYC/CEP8, TBX2/CEP17, and RPS6KB1/CEP17. All malignant and benign lesions, including putative precursor lesions, were studied. The invasive cancers from deleterious mutation carriers had a higher prevalence of duplication of MYC (P = 0.006) and TBX2 (P = 0.0008) compared to controls and a lower prevalence of ERBB2 amplification (P = 0.011). Coduplication of MYC and TBX2 was common in the in situ and invasive lesions from the deleterious mutation carriers. The odds ratio of having a BRCA1/2 mutation is 31.4 (95% CI = 1.7-569) when MYC and TBX2 are coduplicated but ERBB2 is normal. Unclassified variant carriers/no mutation detected and sporadic controls had a similar prevalence of alterations, suggesting that hereditary patients with no deleterious mutations follow a progression pathway similar to that of sporadic cases. With the exception of one atypical ductal hyperplasia lesion, no putative precursor lesion showed any detectable alteration of the probes tested. There was no significant intratumoral heterogeneity of genetic alterations. Our data confirm that a specific pattern of genomic instability characterizes BRCA1/2-related cancers and that this pattern has implications for the biology of these cancers. Moreover, our current and previous results emphasize the interaction between phenotype and genotype in BRCA1/2-related breast cancers and that a combination of morphologic features and alterations of ERBB2, MYC, and TBX2 may better define mechanisms of tumor progression, as well as determine which patients are more likely to carry BRCA1/2 mutations.
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PMID:ERBB2, TBX2, RPS6KB1, and MYC alterations in breast tissues of BRCA1 and BRCA2 mutation carriers. 1554 18

The gene expression profiles of breast cancers can now be determined with microarray technologies which measure the expression of tens of thousands of genes. By applying statistical and bioinformatics tools to gene expression data, tumors can be classified into biologically and clinically relevant categories. In addition to improving tumor classification, gene expression signatures have been identified which are related to BRCA1 and BRCA2 mutation status, ER status, and patient prognosis. Beyond its impact on research into the basic mechanisms of breast tumor progression, continued progress in tumor gene expression profiling appears likely to lead to clinically useful gene expression tests.
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PMID:Gene expression profiling in breast cancer research. 1568 94

The genetic changes underlying in the development and progression of familial breast cancer are poorly understood. To identify a somatic genetic signature of tumor progression for each familial group, BRCA1, BRCA2, and non-BRCA1/BRCA2 (BRCAX) tumors, by high-resolution comparative genomic hybridization, we have analyzed 77 tumors previously characterized for BRCA1 and BRCA2 germ line mutations. Based on a combination of the somatic genetic changes observed at the six most different chromosomal regions and the status of the estrogen receptor, we developed using random forests a molecular classifier, which assigns to a given tumor a probability to belong either to the BRCA1 or to the BRCA2 class. Because 76.5% (26 of 34) of the BRCAX cases were classified with our predictor to the BRCA1 class with a probability of >50%, we analyzed the BRCA1 promoter region for aberrant methylation in all the BRCAX cases. We found that 15 of the 34 BRCAX analyzed tumors had hypermethylation of the BRCA1 gene. When we considered the predictor, we observed that all the cases with this epigenetic event were assigned to the BRCA1 class with a probability of >50%. Interestingly, 84.6% of the cases (11 of 13) assigned to the BRCA1 class with a probability >80% had an aberrant methylation of the BRCA1 promoter. This fact suggests that somatic BRCA1 inactivation could modify the profile of tumor progression in most of the BRCAX cases.
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PMID:A predictor based on the somatic genomic changes of the BRCA1/BRCA2 breast cancer tumors identifies the non-BRCA1/BRCA2 tumors with BRCA1 promoter hypermethylation. 1570 82

Germline mutations in two major susceptibility genes BRCA1 and BRCA2 contribute to the majority of inherited breast and ovarian cancers. Besides the germline mutation, tumor progression depends on the loss of a wild-type allele. Allelic losses in the BRCA1 and BRCA2 loci have also been detected in a high proportion of sporadic breast tumors, suggesting the role of these genes in the development of non-inherited breast cancer. Forty unselected breast tumors were analyzed for the loss of heterozygosity (LOH) at BRCA1 and BRCA2 regions and tumors with allelic deletions were screened for the presence of acquired genetic alterations in respective genes. 21.1% of 38 informative tumor samples carried LOH at the BRCA1 locus whereas 33.3% of 39 informative samples showed LOH at the BRCA2 locus. Pathogenic truncating mutations in the BRCA1 gene were found in two tumor samples with allelic losses, whereas no mutations were identified in the BRCA2 gene. Mutations were not detected in non-tumor samples from the same individuals, which indicated that the BRCA1 allele was inactivated by somatic mutations in tumor tissue. The c.1116G>A (1235G>A) nonsense mutation (p.W372X) belongs to the genetic abnormalities detected infrequently in hereditary tumors; the c.3862delG (3981delG) frameshift mutation (p.E1288fsX1306) is a novel gene alteration. The occurrence of inactivating somatic mutations in sporadic breast tumors suggested the role of the BRCA1 gene in tumorigenesis in at least a minor group of patients with non-familial breast cancer.
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PMID:Novel somatic mutations in the BRCA1 gene in sporadic breast tumors. 1571 67

The molecular genetic profiles that characterize pancreatic ductal neoplasia have taken shape recently with the help of immunohistochemistry and the establishment of the nomenclature describing pancreatic ductal tumorigenesis. K-ras mutations frequently occur early, changes in the expression and genetic integrity of the p16 gene appear in intermediate lesions, and the inactivation of the p53, DPC4, and BRCA2 genes occur late in the neoplastic progression. Tumor-suppressor genes inactivated in pancreatic cancer such as ALK5, TGFBR2, MKK4, and STK11/LKB1 have been identified, although their roles in tumor progression are not yet well defined. Additional discoveries in this tumor system may be on the horizon, will further refine the molecular genetic profiles for the disease, and should suggest some clinical uses for this fund of knowledge.
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PMID:Molecular genetics of ductal pancreatic neoplasia. 1703 Nov 13

BRCA1 and BRCA2 breast cancers have distinct biological features as evidenced by histopathologic, immunohistochemical, gene expression profiling, and array-comparative genomic hybridization data. BRCA1 breast cancers may have a worse prognosis but may, however be amenable to treatment such as chemotherapy for small high-grade, lymph node negative breast cancers. Paradoxically, tamoxifen may provide effective adjuvant and chemopreventive therapy despite the predominantly negative estrogen receptor status of BRCA1 breast cancers. The distinctive biology of BRCA1 and BRCA2 breast cancers bodes well for the development of targeted cancer therapies. Cells with BRCA1 or BRCA2 loss of function are deficient in DNA double strand break repair and are sensitized to poly(ADP-ribose) polymerase (PARP) inhibitors, causing the persistence of DNA lesions which are usually repaired by homologous recombination and ultimately leading to apoptosis. The potentially high efficacy and low toxicity of poly(ADP-ribose) polymerase inhibitors presents an opportunity for targeted cancer therapeutics for BRCA1 and BRCA2 germline mutation carriers. Genotype-tailored chemoprevention may be feasible which could theoretically eliminate single cells that have sustained a second hit, before cancer progression takes place. If targeted cancer therapies emerge, it will become crucially important to identify BRCA carriers at the time of diagnosis for optimal therapy and to identify unaffected carriers for chemoprevention. If so, then to the extent that barriers in the recognition and referral of patients to genetic counseling cannot be surmounted, pathological and genomic methods to identify a BRCA1 or BRCA2 breast cancer profile will gain increasing clinical importance.
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PMID:Hereditary breast cancer: pathobiology, clinical translation, and potential for targeted cancer therapeutics. 1762 1

We used mathematical models to analyze the age-incidence curve of breast carcinoma for individuals carrying a germline mutation in the BRCA1 or BRCA2 gene locus. Although many genomic abnormalities have been identified in breast tumors, we found that a two-stage model fit the data well. A one-hit model was not, however, consistent with the data. The results supported the hypothesis that the first hit represents loss of the wild type BRCA1 or BRCA2 allele as this occurs at a rate very similar to that for loss of the wild-type RB allele in retinoblastoma. Loss of the wild-type BRCA1 or BRCA2 allele appears to destabilize the genome as the second event occurs at a much higher rate. The second event is "rate limiting" in the sense that its occurrence is constrained by the limited number of intermediate cells with doubly mutated BRCA1 or BRCA2 alleles. The second event may not be unique, however. Loss of the wild-type BRCA allele appears to result in an increased rate for subsequent genomic events. A second event increasing proliferation of the partially malignant intermediate clone may lead inexorably to production and selection of cells with additional mutations in genes that facilitate tumor progression.
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PMID:On the dynamics of breast tumor development in women carrying germline BRCA1 and BRCA2 mutations. 1809 85

Homozygous loss of activity at the breast cancerpredisposing genes BRCA1 and BRCA2 (FANCD1) confers increased susceptibility to DNA double strand breaks, but this genotype occurs only in the tumor itself, following loss of heterozygosity at one of these loci. Thus, if these genes play a role in tumor etiology as opposed to tumor progression, they must manifest a heterozygous phenotype at the cellular level. To investigate the potential consequences of somatic heterozygosity for a BRCA1 mutation demonstrably associated with breast carcinogenesis on background somatic mutational burden, we applied the two standard assays of in vivo human somatic mutation to blood samples from a manifesting carrier of the Q1200X mutation in BRCA1 whose tumor was uniquely ascertained through an MRI screening study. The patient had an allele-loss mutation frequency of 19.4 x 10(-6) at the autosomal GPA locus in erythrocytes and 17.1 x 10(-6) at the X-linked HPRT locus in lymphocytes. Both of these mutation frequencies are significantly higher than expected from age-matched disease-free controls (P < 0.05). Mutation at the HPRT locus was similarly elevated in lymphoblastoid cell lines established from three other BRCA1 mutation carriers with breast cancer. Our patient's GPA mutation frequency is below the level established for diagnosis of homozygous Fanconi anemia patients, but consistent with data from obligate heterozygotes. The increased HPRT mutation frequency is more reminiscent of data from patients with xeroderma pigmentosum, a disease characterized by UV sensitivity and deficiency in the nucleotide excision pathway of DNA repair. Therefore, this BRCA1-associated breast cancer patient manifests a unique phenotype of increased background mutagenesis that likely contributed to the development of her disease independent of loss of heterozygosity at the susceptibility locus.
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PMID:Elevated levels of somatic mutation in a manifesting BRCA1 mutation carrier. 1815 61

Non-muscle invasive bladder cancer is a heterogenous disease whose management is dependent upon the risk of progression to muscle invasion. Although the recurrence rate is high, the majority of tumors are indolent and can be managed by endoscopic means alone. The prognosis of muscle invasion is poor and radical treatment is required if cure is to be obtained. Progression risk in non-invasive tumors is hard to determine at tumor diagnosis using current clinicopathological means. To improve the accuracy of progression prediction various biomarkers have been evaluated. To discover novel biomarkers several authors have used gene expression microarrays. Various statistical methods have been described to interpret array data, but to date no biomarkers have entered clinical practice. Here, we describe a new method of microarray analysis using neurofuzzy modeling (NFM), a form of artificial intelligence, and integrate it with artificial neural networks (ANN) to investigate non-muscle invasive bladder cancer array data (n=66 tumors). We develop a predictive panel of 11 genes, from 2800 expressed genes, that can significantly identify tumor progression (average Logrank p = 0.0288) in the analyzed cancers. In comparison, this panel appears superior to those genes chosen using traditional analyses (average Logrank p = 0.3455) and tumor grade (Logrank, p = 0.2475) in this non-muscle invasive cohort. We then analyze panel members in a new non-muscle invasive bladder cancer cohort (n=199) using immunohistochemistry with six commercially available antibodies. The combination of 6 genes (LIG3, TNFRSF6, KRT18, ICAM1, DSG2 and BRCA2) significantly stratifies tumor progression (Logrank p = 0.0096) in the new cohort. We discuss the benefits of the transparent NFM approach with respect to other reported methods.
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PMID:Artificial intelligence and bladder cancer arrays. 1831 29


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