Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The genetic determinants for most breast cancer cases remain elusive. Whilst mutations in BRCA1 and BRCA2 significantly contribute to familial breast cancer risk, their contribution to sporadic breast cancer is low. In such cases genes frequently altered in the general population, such as the gene mutated in Ataxia telangiectasia (AT), ATM may be important risk factors. The initial interest in studying ATM heterozygosity in breast cancer arose from the findings of epidemiological studies of AT families in which AT heterozygote women had an increased risk of breast cancer and estimations that 1% of the population are AT heterozygotes. One of the clinical features of AT patients is extreme cellular sensitivity to ionising radiation. This observation, together with the finding that a significant proportion of breast cancer patients show an exaggerated acute or late normal tissue reactions after radiotherapy, has lead to the suggestion that AT heterozygosity plays a role in radiosensitivity and breast cancer development. Loss of heterozygosity in the region of the ATM gene on chromosome 11, has been found in about 40% of sporadic breast tumours. However, screening for ATM mutations in sporadic breast cancer cases, showing or not adverse effects to radiotherapy, has not revealed the magnitude of involvement of the ATM gene expected. Their size and the use of the protein truncation test to identify mutations limit many of these studies. This latter parameter is critical as the profile of mutations in AT patients may not be representative of the ATM mutations in other diseases. The potential role of rare sequence variants within the ATM gene, sometimes reported as polymorphisms, also needs to be fully assessed in larger cohorts of breast cancer patients and controls in order to determine whether they represent cancer and/or radiation sensitivity predisposing mutations.
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PMID:The ATM gene and breast cancer: is it really a risk factor? 1076 28

The medical histories of breast cancer-prone families have been described for over a century. The pattern of breast cancer occurrences in these families is most consistent with an autosomal dominant mode of inheritance. The location of a gene that could explain the pattern of transmission of the breast cancer trait in families averaging early (pre-menopausal) onset of breast cancer was reported in 1990. Since then, two genes have been identified: BRCA1 and BRCA2. Germ-line mutations in these two genes confer susceptibility to breast (female and male) and ovarian cancer, and account for a significant proportion of hereditary breast cancer in two cancer syndromes: site-specific breast cancer and the breast-ovarian cancer syndrome. Other hereditary syndromes that feature breast cancer are Li-Fraumeni syndrome, Cowden disease, and ataxia telangiectasia, whose carriers have been shown to harbor germ-line mutations in TP53, PTEN, and ATM, respectively. There may be other genetic factors that contribute to hereditary breast cancer, since not all families with multiple cases of breast cancer harbor germ-line BRCA1 or BRCA2 mutations. Host factors (such as lifestyle choices) and other genes may modulate risk of breast cancer in mutation carriers.
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PMID:Genes implicated in hereditary breast cancer syndromes. 1080 49

Recent studies have elucidated some of the molecular and cellular mechanisms that determine the sensitivity or resistance to ionizing radiation. These findings ultimately may be useful in devising new strategies to improve the therapeutic ratio in cancer treatment. Despite the rapid advances in knowledge of cellular functions that affect radiosensitivity, we still cannot account for most of the clinically observed heterogeneity of normal tissue and tumor responses to radiotherapy, nor can we accurately predict which individual tumors will be controlled locally and which patients will develop more severe normal tissue damage after radiotherapy. However, several candidate genes for which deletion or loss of function mutations may be associated with altered cellular radiosensitivity (e.g., ATM, p53, BRCA1, BRCA2, DNA-PK) have been identified. Some of the differences in normal tissue sensitivity to radiation may stem from mutations with milder effects, heterozygosity, or polymorphisms of these genes. Finally, molecular mechanisms linking genetic instability, radiosensitivity, and predisposition to cancer are being unraveled.
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PMID:Biological basis of radiation sensitivity. Part 2: Cellular and molecular determinants of radiosensitivity. 1085 63

Germline mutations of BRCA1 predispose women to breast and ovarian cancers. BRCA1 contains several functional domains that interact directly or indirectly with a variety of molecules, including tumor suppressors (p53, RB, BRCA2 and ATM), oncogenes (c-Myc, casein kinase II and E2F), DNA damage repair proteins (RAD50 and RAD51), cell-cycle regulators (cyclins and cyclin-dependent kinases), transcriptional activators and repressors (RNA polymerase II, RHA, histone deacetylase complex and CtIP) and others. Mounting evidence indicates that these physical associations are not artifacts; rather, BRCA1 is likely to serve as an important central component in multiple biological pathways that regulate cell-cycle progression, centrosome duplication, DNA damage repair, cell growth and apoptosis, and transcriptional activation and repression. This review examines our understanding of the significance of the interactions between BRCA1 and other proteins, through which BRCA1 maintains genome integrity and represses tumor formation. Published 2000 John Wiley & Sons, Inc.
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PMID:Roles of BRCA1 and its interacting proteins. 1091 3

Breast cancer is considered to display a high degree of intratumor heterogeneity, without any obvious morphological and pathological steps to define sequential evolution, and its progression may vary among individual tumors. In an attempt to elucidate these etiological and phenotypic complexities, the present study, based on the fundamental concept that genomic instability is the engine of both tumor progression and tumor heterogeneity, was conducted to test the hypothesis that breast cancer pathogenesis is driven by double-strand break (DSB)-initiated chromosome instability (CIN). The rationale underlying this hypothesis is derived from the clues provided by family breast cancer syndromes, in which susceptibility genes, including p53, ATM, BRCA1 and BRCA2, are involved within the common functional pathway of DSB-related checkpoint/ repair. Because genomic deletion caused by DSB is reflected in the genetic mechanism of loss of heterozygosity (LOH), this genome-wide LOH study was conducted, using 100 tumors and 400 microsatellite markers. To minimize the effect of heterogeneity within tumors, the experimental technique of laser capture microdissection was used to ensure that genetic and phenotypic examinations were based on the same tumor cells. Support for our hypothesis comes from the observations that: (a) the extent of DSB-initiated CIN in tumors significantly increased as tumors progressed to poorer grades or later stages; (b) in the sequential steps toward CIN, the loci of p53 and ATM, the key checkpoint genes against DSB, were lost at the earliest stage; and (c) many loci identified to be important in breast tumorigenesis were the genomic sites possibly harboring the genes involved in DSB-related checkpoint/repair (including RAD51, RAD52, and BRCA1) or CIN (including FA-A, FA-D, and WRN), and a higher number of these loci showing LOH was significantly associated with increased level of DSB-initiated CIN (P < 0.0001). Breast cancers are thus considered to be sequentially progressive with CIN. However, CIN might also cause genetic heterogeneity, which was revealed by the findings that LOH at some markers was observed only in the component of ductal carcinoma in situ but not in the invasive component of the same tumors. In addition, some markers were found to preferentially lose at specific tumor grades, implying their contribution to genetic heterogeneity during tumor development. Therefore, this study suggests that breast cancer progression is clonal with regard to CIN, but different breast cancers would present distinct molecular profiles resulting from genetic heterogeneity caused by CIN.
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PMID:Genome-wide search for loss of heterozygosity using laser capture microdissected tissue of breast carcinoma: an implication for mutator phenotype and breast cancer pathogenesis. 1091 64

The hereditary breast (BC) and ovarian (OC) cancer syndrome (HBOC) includes genetic alterations of various susceptibility genes such as TP53, ATM, PTEN or MSH2, MLH1, PMS1, PMS2, MSH3 and MSH6, BRCA1 and BRCA2. Germline mutations of the cancer-susceptibility genes BRCA1 and BRCA2 seem to be the major aetiology of the HBOC. Genetic counselling and identification of high-risk families may be essential (1) to provide the best method for genetic testing by explaining the sensitivity and specificity of the methods, (2) to offer the opportunity to participate in specific early cancer detection programmes (breast (self) palpation, ultrasound, mammography and magnetic resonance tomography for breast cancer; vaginal exploration and ultrasound for ovarian cancer), (3) to inform them about prophylactic medication (oral contraceptive pill (OCP), chemoprevention (tamoxifen, raloxifen, aromatase inhibitors)) or surgery (bilateral prophylactic mastectomy or oophorectomy) and (4) to provide individualized psychological support. To fulfil these broad demands, an inter-disciplinary counselling approach (gynaecological oncology, human genetics, molecular biology, psychotherapy) in the setting of a cancer genetic clinic seems the most appropriate. There, participation in predictive genetic testing or the use of preventive or therapeutic options may be discussed extensively with the subjects. In particular, preventive options are emotionally disturbing for the subjects, and in cases of previous cancer. BC chemoprevention for high-risk women does not seem to be as effective as expected. However, OCP reduces the risk for OC. For prophylactic surgery, various points have to be considered, including: (1) individual risk assessment and gain in life expectancy, (2) value of screening and early detection methods or medical prevention, (3) disease characteristics and prognosis, and (4) anxiety and quality of life. Decisions regarding these options have to be individualized and psychological support must be offered during the period of decision and follow-up.
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PMID:Prevention and therapy for BRCA1/2 mutation carriers and women at high risk for breast and ovarian cancer. 1095 53

We have provided an overview of recent studies that have greatly expanded our knowledge of the molecular and cellular mechanisms that determine the sensitivity or resistance to ionizing radiation. Much of this knowledge was obtained by studying tumor and nontumor cell types that under- or overexpress proteins involved in the regulation of the DNA damage response, cell cycle progression, growth factor signal transduction, and apoptosis. These findings may ultimately be useful in devising new strategies to improve the therapeutic ratio in cancer treatment. Despite the rapid advances in knowledge of cellular functions that affect radiosensitivity, we still cannot account for most of the clinically observed heterogeneity of normal tissue and tumor responses to radiotherapy; nor can we accurately predict which individual tumors will be locally controlled and which patients will develop more severe normal tissue damage after radiotherapy. However, several candidate genes for which deletion or loss of function mutations may be associated with altered cellular radiosensitivity (e.g., ATM, p53, BRCA2) have been identified. Some of the differences in normal tissue sensitivity to radiation may occur because of mutations with milder effects, heterozygosity, or polymorphisms of these genes. Finally, molecular mechanisms linking genetic instability, radiosensitivity, and predisposition to cancer are being examined.
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PMID:The molecular and cellular basis of radiosensitivity: implications for understanding how normal tissues and tumors respond to therapeutic radiation. 1099 50

Women who develop bilateral breast cancer at an early age are likely to harbour germline mutations in breast cancer susceptibility genes. The aim of this study was to test for concordant genetic changes in left and right breast cancer of young women (age < 50) with bilateral breast cancer that may suggest an inherited breast cancer predisposition. Microsatellite markers were used to test for loss of heterozygosity (LOH) in left and right tumours for 31 women with premenopausal bilateral breast cancer. Markers adjacent to or within candidate genes on 17p (p53), 17q (BRCA1), 13q (BRCA2), 11q (Ataxia Telangiectasia-ATM) and 3p (FHIT) were chosen. Mutational testing for BRCA1 and BRCA2 was performed for cases where blood was available. Concordant LOH in both left and right tumours was demonstrated for at least one of the markers tested in 16/31(54%) cases. Where allelic loss was demonstrated for both left and right breast cancer, the same allele was lost on each occasion. This may suggest a common mutational event. Four cases showed concordant loss of alleles in both left and right breast cancer at D17S791 (BRCA1). BRCA1 mutations were identified in two of these cases where blood was available. Four cases showed concordant LOH at D13S155 (BRCA2). Concordant LOH was further demonstrated in seven cases for D11S1778 (ATM) and four cases for D3S1300 (which maps to the FHIT gene), suggesting a possible role for these tumour suppressor genes in this subgroup of breast cancer patients. No concordant allelic loss was demonstrated for D17S786 suggesting that germline mutations in p53 are unlikely in such cases of bilateral breast cancer.
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PMID:Loss of heterozygosity in bilateral breast cancer. 1120 Jul 74

To gain insight into the molecular mechanisms underlying the inherited predisposition to breast cancer in non-Ashkenazi Jews, we genotyped 54 Jewish Moroccan women with breast cancer, unselected for family history of cancer, for the predominant Jewish mutations in BRCA1, BRCA2, and ATM. One patient (2%) was found to have the 185de1AG BRCA1 mutation, none was a carrier of the 6174delT BRCA2 mutation, and 2/54 (4%) were heterozygous for the ATM mutation. These rates were not significantly different from the rates in the general non-Ashkenazi population. These preliminary data may indicate that the predominant Jewish mutations in BRCA1, BRCA2, and ATM genes contribute little, if any, to breast cancer predisposition and risk among Moroccan Jews.
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PMID:The founder mutations in the BRCA1, BRCA2, and ATM genes in Moroccan Jewish women with breast cancer. 1121 67

The great majority of breast cancer cases are not associated with a mutated gene of high penetrance such as BRCA1, BRCA2 and TP53. Genes of low penetrance, frequently mutated in the general population, might play an important role in breast cancer development. The ATM gene, which encodes the ATM protein, mutated in the disorder ataxia telangiectasia (AT) could be such a susceptibility gene. Indeed, 1% of the general population is estimated to be AT heterozygote and females have an increased risk of developing breast cancer. The ATM protein is involved in the signalling pathway of DNA double-strand breaks. Studies on its expression in normal breast tissues have shown that ATM is expressed in the epithelial cells of breast ducts, but not in the myoepithelial cells. In sclerosing adenosis, a benign lesion of the breast, the ATM protein is expressed in both cell types whereas its expression is absent or reduced in tumour epithelial cells in about 30-50% of invasive carcinomas. Moreover, the study of the p53 status in some of these tumours has revealed that the ATM/p53 signalling pathway is frequently altered either by a very low ATM expression or by the presence of a mutated p53. It remains to be determined whether alterations in the expression of other proteins also involved in this DNA damage signalling cascade are specifically associated with breast cancer development and/or a radiosensitive phenotype seen in some breast cancer patients after radiotherapy.
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PMID:[What do we know about ATM protein expression in breast tissue?]. 1149 20


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