UMLS:C0006142 - FACTA Search

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Query: UMLS:C0006142 (breast cancer)
160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previously we analysed overlapping homozygous deletions in lung and breast tumours/tumour lines and defined a small region of 120 kb (part of LCTSGR1) at 3p21.3 that contained putative lung and breast cancer tumour suppressor gene(s) (TSG). Eight genes including RASSF1 were isolated from the minimal region. However, extensive mutation analysis in lung tumours and tumour lines revealed only rare inactivating mutations. Recently, de novo methylation at a CpG island associated with isoform A of RASSF1 (RASSF1A) was reported in lung tumours and tumour lines. To investigate RASSF1A as a candidate TSG for various cancers, we investigated: (a) RASSF1A methylation status in a large series of primary tumour and tumour lines; (b) chromosome 3p allele loss in lung tumours and (c) RASSF1 mutation analysis in breast tumours. RASSF1A promoter region CpG island methylation was detected in 72% of SCLC, 34% of NSCLC, 9% of breast, 10% of ovarian and 0% of primary cervical tumours and in 72% SCLC, 36% NSCLC, 80% of breast and 40% of ovarian tumour lines. In view of the lower frequency of RASSF1 methylation in primary breast cancers we proceeded to RASSF1 mutation analysis in 40 breast cancers. No mutations were detected, but six single nucleotide polymorphisms were identified. Twenty of 26 SCLC tumours with 3p21.3 allelic loss had RASSF1A methylation, while only six out of 22 NSCLC with 3p21.3 allele loss had RASSF1A methylation (P=0.0012), one out of five ovarian and none out of six cervical tumours with 3p21.3 loss had RASSF1A methylation. These results suggest that (a) RASSF1A inactivation by two hits (methylation and loss) is a critical step in SCLC tumourigenesis and (b) RASSF1A inactivation is of lesser importance in NSCLC, breast, ovarian and cervical cancers in which other genes within LCTSGR1 are likely to be implicated.
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PMID:Methylation associated inactivation of RASSF1A from region 3p21.3 in lung, breast and ovarian tumours. 1131 94

The aberrant methylation of cytosine residues in the promoter region of growth regulatory genes is now widely recognized as an additional mechanism for gene inactivation in cancer cells. In this study we analyzed the methylation status of four growth regulatory genes (p16, RASSF1A, cyclinD2, 14-3-3zeta) during breast cancer progression. For this purpose invasive and noninvasive tumor cell populations as well as hyperplastic cell proliferations were isolated from a series of archival breast tissue specimens (n = 57) using laser-assisted microdissection. A new real-time polymerase chain reaction-based assay was used for the sensitive and quantitative determination of the cell-specific methylation status. We found that aberrant promoter methylation was already prevalent in pure intraductal carcinoma with different frequencies and different methylation levels for the four genes analyzed. For RASSF1A and 14-3-3zeta promoter methylation was also demonstrated in epithelial hyperplasia and intraductal papillomas. By contrast, aberrant methylation of cyclinD2 and p16 was restricted to cancerous epithelium. Increased methylation of the cyclinD2 gene was significantly associated with a higher van Nuys grade. Furthermore, when intraductal and invasive tumor cells were compared, significant quantitative changes in the methylation level were detected primarily within the cyclinD2 gene. These results demonstrate that promoter methylation is an early and frequent event in breast cancer development, but displays great quantitative and gene-specific differences, and changes in a gene-specific manner during tumor progression.
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PMID:Quantitative assessment of promoter hypermethylation during breast cancer development. 1183 81

Expression of death-associated protein (DAP) kinase, a proapoptotic serine/threonine protein kinase, is frequently lost in human tumors. In a study of 134 primary breast cancer specimens hypermethylation of the DAP kinase gene was found in 13% of cases. A highly significant difference (P < 0.001) of DAP kinase inactivation was observed between invasive lobular cancer (n = 19) and invasive ductal cancer (n = 85; 53% versus 9%, respectively). Hypermethylation correlated with loss of RNA expression, estrogen receptor positivity (P < 0.01), and the absence of p53 overexpression (P < 0.01). In contrast to invasive lobular cancer, the in situ-growing precursor lesion lacked epigenetic modification of the DAP kinase promotor by aberrant methylation indicating a potential role in tumor progression. Unlike the DAP kinase gene, hypermethylation of the cyclin D2 and RASSF1A genes did not correlate with a particular histological subtype or to invasiveness [corrected]. We conclude that different histological subtypes of breast cancer may not only differ concerning specific chromosomal abnormalities and DNA mutations but also with regard to epigenetic inactivation patterns.
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PMID:Promoter hypermethylation of the death-associated protein kinase gene in breast cancer is associated with the invasive lobular subtype. 1243 60

The newly identified 3p21.3 tumour suppressor gene RASSF1A is methylated in the majority of primary lung tumours, lung tumour cell lines and in a variable percentage of breast tumours. To determine the extent of RASSF1A promoter hypermethylation in early lung tumorigenesis, we analysed sputum samples from lung cancer patients and from current and former smokers using a sensitive methylation-specific PCR (MSP) technique. We also analysed RASSF1A promoter region hypermethylation in trios of normal breast/invasive ductal breast carcinoma/ductal carcinoma in situ (DCIS) from breast cancer patients and DCIS without invasive cancer. We found that 50% of small cell lung cancer (SCLC) and 21% of non-small cell lung cancer (NSCLC) patients had RASSF1A methylation, while one of two former smokers and four of 13 current smokers demonstrated RASSF1A methylation in sputum. Furthermore, two of the four current smokers and one former smoker showing RASSF1A methylation in their sputum developed cancer within 12-14 months of bronchoscopy. In our breast cancer trios, RASSF1A promoter hypermethylation was detected in 65% of invasive cancers, in 42% of corresponding DCIS but in none of the normal breast samples. In addition, we found that three out of 10 DCIS without invasive breast cancer also underwent RASSF1A promoter hypermethylation. Our findings suggest that RASSF1A promoter region hypermethylation may be a useful molecular marker for early detection of lung cancer. Furthermore, since RASSF1A promoter hypermethylation was detected in ductal carcinoma in situ, inactivation of RASSF1A may be an early event in breast tumorigenesis.
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PMID:Detection of RASSF1A aberrant promoter hypermethylation in sputum from chronic smokers and ductal carcinoma in situ from breast cancer patients. 1252 16

Hypermethylation of multiple CpG islands is a common event in cancer. To assess the prognostic values of this epigenetic alteration, we developed Methylation Target Array (MTA), derived from the concept of tissue microarray, for simultaneous analysis of DNA hypermethylation in hundreds of tissue genomes. In MTA, linker-ligated CpG island fragments were digested with methylation-sensitive endonucleases and amplified with flanking primers. A panel of 468 MTA amplicons, which represented the whole repertoire of methylated CpG islands in 93 breast tumors, 20 normal breast tissues, and 4 breast cancer cell lines, were arrayed on nylon membrane for probe hybridization. Positive hybridization signals detected in tumor amplicons, but not in normal amplicons, were indicative of aberrant hypermethylation in tumor samples. This is attributed to aberrant sites that were protected from methylation-sensitive restriction and were amplified by PCR in tumor samples, while the same sites were restricted and could not be amplified in normal samples. Hypermethylation frequencies of the 10 genes tested in breast tumors and cancer cell lines were 60% for GPC3, 58% for RASSF1A, 32% for 3OST3B, 30% for HOXA5, 28% for uPA, 25% for WT1, 23% for BRCA1, 9% for DAPK1, and 0% for KL. Furthermore, hypermethylation of 5 to 7 loci of these genes was significantly correlated with hormone receptor status, clinical stages, and ages at diagnosis of the patients analyzed. This novel approach thus provides an additional avenue for assessing clinicopathological consequences of DNA hypermethylation in breast cancer.
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PMID:Methylation target array for rapid analysis of CpG island hypermethylation in multiple tissue genomes. 1281 9

Aberrant DNA methylation of promoter CpG islands is associated with transcriptionally repressive heterochromatin in neoplasia. The dynamics of this epigenetic process in mediating the transition from an active to an inactive state of transcription remains to be elucidated, however. Here, we used the methylation-specific oligonucleotide microarray to map the methylation patterns of a CpG island, located within the promoter and the first exon regions of RASSF1A, in normal breast tissue controls, primary tumors, and breast cancer cell lines. Oligonucleotide pairs, spaced along the CpG island region, were designed to discriminate between methylated and unmethylated alleles of selected sites. The methylation-specific oligonucleotide data indicate that the majority of test samples show widespread methylation in the first exon of RASSF1A. In contrast, the promoter area was usually undermethylated in normal controls and in 32% of the primary tumors tested, whereas the rest of the primary tumors and breast cancer cell lines showed various degrees of methylation in the region. Methylation profiling of individual tumors further suggest that DNA methylation progressively spreads from the first exon into the promoter area of this gene. Functional analysis indicates that increased density of RASSF1A promoter methylation is associated with altered chromatin, marked by a depletion of acetylated histones and methylated histone 3-lysine 4 and an enrichment of methylated histone 3-lysine 9 in the studied area. The combination of these epigenetic modifications may engender a stable silencing of the gene in breast cancer cells. Thus, this study underscores the importance of detailed mapping of methylation patterns within a CpG island locus that may provide insights into the progressive nature of aberrant DNA methylation and its relationship with transcriptional silencing during the neoplastic process.
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PMID:Differential distribution of DNA methylation within the RASSF1A CpG island in breast cancer. 1455 1

Methylation of tumor suppressor genes has been implicated in breast cancer development. However, methylation profiles of different breast lesions, subtypes of carcinoma in particular, have not been examined in detail. In this study, we use methylation-specific PCR (MSP) to generate gene methylation profiles of different breast lesions and to test the clinical utility of such profiles. We examined the methylation status of three genes, RARbeta2, RASSF1A, and cyclin D2, on 102 samples of breast tissue, from benign (n = 36), to in situ carcinoma (n = 21), to invasive carcinoma (n = 45). We found that almost all cases of invasive carcinoma (96%) contained at least one methylated gene from our panel, whereas gene methylation was less common among benign lesions (42%) and in situ carcinoma (76%). Of the three genes, cyclin D2 methylation was most specific for malignancy because only 1 of 35 benign cases was methylated at this gene (1 case was not informative). The major histologic subtypes of invasive carcinoma show similar methylation profiles in the genes examined. We next performed MSP analysis on archival breast fine-needle aspiration (FNA) biopsy samples and corresponding surgical biopsy specimens and found a high concordance between the two types of specimens. We then analyzed 17 breast FNA biopsy samples with an indeterminate diagnosis. In this setting, MSP had a high specificity (100%) and modest sensitivity (67%) for identifying malignancy.
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PMID:Methylation profiling of benign and malignant breast lesions and its application to cytopathology. 1461 48

Changes in the status of DNA methylation are one of the most common molecular alterations in human neoplasia. Because it is possible to detect these epigenetic alterations in the bloodstream of patients, we investigated whether aberrant DNA methylation in patient pretherapeutic sera is of prognostic significance in breast cancer. Using MethyLight, a high-throughput DNA methylation assay, we analyzed 39 genes in a gene evaluation set, consisting of 10 sera from metastasized patients, 26 patients with primary breast cancer, and 10 control patients. To determine the prognostic value of genes identified within the gene evaluation set, we finally analyzed pretreatment sera of 24 patients having had no adjuvant treatment (training set) to determine their prognostic value. An independent test set consisting of 62 patients was then used to test the validity of genes and combinations of genes, which in the training set were found to be good prognostic markers. In the gene evaluation set we identified five genes (ESR1, APC, HSD17B4, HIC1, and RASSF1A). In the training set, patients with methylated serum DNA for RASSF1A and/or APC had the worst prognosis (P < 0.001). This finding was confirmed by analyzing serum samples from the independent test set (P = 0.007). When analyzing all 86 of the investigated patients, multivariate analysis showed methylated RASSF1A and/or APC serum DNA to be independently associated with poor outcome, with a relative risk for death of 5.7. DNA methylation of particular genes in pretherapeutic sera of breast cancer patients, especially of RASSF1A/APC, is more powerful than standard prognostic parameters.
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PMID:DNA methylation in serum of breast cancer patients: an independent prognostic marker. 1463 83

DNA methyltransferase 1 (DNMT1) is required to maintain DNA methylation patterns in mammalian cells, and is thought to be the predominant maintenance methyltransferase gene. Recent studies indicate that inhibiting DNMT1 protein expression may be a useful approach for understanding the role of DNA methylation in tumorigenesis. To this end, we used RNA interference to specifically down-regulate DNMT1 protein expression in NCI-H1299 lung cancer and HCC1954 breast cancer cells. RNA interference-mediated knockdown of DNMT1 protein expression resulted in >80% reduction of promoter methylation in RASSF1A, p16(ink4A), and CDH1 in NCI-H1299; and RASSF1A, p16(ink4A), and HPP1 in HCC1954; and re-expression of p16(ink4A), CDH1, RASSF1A, and SEMA3B in NCI-H1299; and p16(ink4A), RASSF1A, and HPP1 in HCC1954. By contrast, promoter methylation and lack of gene expression was maintained when these cell lines were treated with control small interfering RNAs. The small interfering RNA treatment was stopped and 17 days later, all of the sequences showed promoter methylation and gene expression was again dramatically down-regulated, indicating the tumor cells still were programmed for these epigenetic changes. We saw no effects on soft agar colony formation of H1299 cells 14 days after DNMT1 knockdown indicating that either these genes are not functioning as tumor suppressors under these conditions, or that more prolonged knockdown or other factors are also required to inhibit the malignant phenotype. These results provide direct evidence that loss of DNMT1 expression abrogates tumor-associated promoter methylation and the resultant silencing of multiple genes implicated in the pathogenesis of human lung and breast cancer.
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PMID:RNA interference-mediated knockdown of DNA methyltransferase 1 leads to promoter demethylation and gene re-expression in human lung and breast cancer cells. 1512 51

If detected early, breast cancer is eminently curable. To detect breast cancer in samples with little cellularity, a high level of sensitivity is needed. Tumor-specific promoter hypermethylation has provided such a valuable tool for detection of cancer cells in biological samples. To accurately assess promoter hypermethylation for many genes simultaneously in small samples, we developed a novel method, quantitative multiplex-methylation-specific PCR (QM-MSP). QM-MSP is highly sensitive (1 in 10(4)-10(5) copies of DNA) and linear over 5 orders of magnitude. For RASSF1A, TWIST, Cyclin D2, and HIN1, we observed significant differences in both the degree (P < 0.003) and incidence (P < 0.02) of hypermethylation between normal and malignant breast tissues. Evaluation of the cumulative hypermethylation of the four genes within each sample revealed a high level of sensitivity (84%) and specificity (89%) of detection of methylation. We demonstrate the application of this technique for detecting hypermethylated RASSF1A, TWIST, Cyclin D2, HIN1, and RARB in 50-1000 epithelial cells collected from breast ducts during endoscopy or by lavage. Such an approach could be used in a variety of small samples derived from different tissues, with these or different biomarkers to enhance detection of malignancy.
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PMID:Quantitative multiplex methylation-specific PCR assay for the detection of promoter hypermethylation in multiple genes in breast cancer. 1523 53

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