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)

Melanoma is the most fatal skin cancer, often highly resistant to chemotherapy. Here we show that treatment with an 11-base DNA oligonucleotide homologous to the telomere 3' overhang sequence (T-oligo) induces apoptosis of several established human melanoma cell lines, including the aggressive MM-AN line, whereas normal human melanocytes exposed to the same or higher T-oligo concentrations show only transient cell cycle arrest, implying that malignant cells are more sensitive to T-oligo effects. When MM-AN cells were briefly exposed to T-oligo in culture and injected into the flank or tail vein of SCID mice, eventual tumor volume and number of metastases were reduced 85-95% compared with control mice. Similarly, T-oligos administered intralesionally or systemically selectively inhibited the growth of previously established MM-AN tumor nodules in the flank and peritoneal cavity by 85 to 90% without detectable toxicity. We previously showed that T-oligos act through ATM, p95/Nbs1, E2F1, p16INK4A, p53, and the p53 homologue p73 to modulate downstream effectors and now additionally demonstrate striking down-regulation of the inhibitor of apoptosis protein livin/ML-IAP. We suggest that T-oligo mimics a physiologic DNA damage signal that is frequently masked in malignant cells and thereby activates innate cancer prevention responses. T-oligos may provide a novel therapeutic approach to melanoma.
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PMID:Telomere-based DNA damage responses: a new approach to melanoma. 1533 80

Mutations in Artemis in both humans and mice result in severe combined immunodeficiency due to a defect in V(D)J recombination. In addition, Artemis mutants are radiosensitive and chromosomally unstable, which has been attributed to a defect in nonhomologous end joining (NHEJ). We show here, however, that Artemis-depleted cell extracts are not defective in NHEJ and that Artemis-deficient cells have normal repair kinetics of double-strand breaks after exposure to ionizing radiation (IR). Artemis is shown, however, to interact with known cell cycle checkpoint proteins and to be a phosphorylation target of the checkpoint kinase ATM or ATR after exposure of cells to IR or UV irradiation, respectively. Consistent with these findings, our results also show that Artemis is required for the maintenance of a normal DNA damage-induced G2/M cell cycle arrest. Artemis does not appear, however, to act either upstream or downstream of checkpoint kinase Chk1 or Chk2. These results define Artemis as having a checkpoint function and suggest that the radiosensitivity and chromosomal instability of Artemis-deficient cells may be due to defects in cell cycle responses after DNA damage.
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PMID:Artemis is a phosphorylation target of ATM and ATR and is involved in the G2/M DNA damage checkpoint response. 1545 91

Artemis plays a crucial role in the hairpin-opening step of antigen receptor VDJ gene recombination in the presence of catalytic subunit of deoxyribonucleic acid (DNA)-dependent protein kinase (DNA-PKcs). A defect in Artemis causes human radiosensitive-severe combined immunodeficiency. Cells from Artemis-deficient patients and mice display increased chromosomal instability, but the precise function of this factor in the response to DNA damage remains to be elucidate. In this study, we show that Artemis is hyperphosphorylated in an Ataxia-telangiectasia-mutated (ATM)- and Nijmegen breakage syndrome 1 (Nbs1)-dependent manner in response to ionizing radiation (IR), and that S645 is an SQ/TQ site that contributes to retarded mobility of Artemis upon IR. The hyperphosphorylation of Artemis is markedly reduced in ATM- and Nbs1-null cells. Reintroduction of wild-type ATM or Nbs1 reconstituted Artemis hyperphosphorylation in ATM- or Nbs1-deficient cells, respectively. In support of this functional link, hyperphosphorylated Artemis was found to physically associate with the Mre11/Rad50/Nbs1 complex in an ATM-dependent manner in response to IR-induced DNA double strand breaks (DSB). Since deficiency of either DNA-Pkcs or ATM leads to defective repair of IR-induced DSB, our finding places Artemis at the signaling crossroads downstream of DNA-PKcs and ATM in IR-induced DSB repair.
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PMID:Ataxia-telangiectasia-mutated dependent phosphorylation of Artemis in response to DNA damage. 1572 59

The Artemis nuclease is defective in radiosensitive severe combined immunodeficiency patients and is required for the repair of a subset of ionising radiation induced DNA double-strand breaks (DSBs) in an ATM and DNA-PK dependent process. Here, we show that Artemis phosphorylation by ATM and DNA-PK in vitro is primarily attributable to S503, S516 and S645 and demonstrate ATM dependent phosphorylation at serine 645 in vivo. However, analysis of multisite phosphorylation mutants of Artemis demonstrates that Artemis phosphorylation is dispensable for endonuclease activity in vitro and for DSB repair and V(D)J recombination in vivo. Importantly, DNA-dependent protein kinase catalytic subunit (DNA-PKcs) autophosphorylation at the T2609-T2647 cluster, in the presence of Ku and target DNA, is required for Artemis-mediated endonuclease activity. Moreover, autophosphorylated DNA-PKcs stably associates with Ku-bound DNA with large single-stranded overhangs until overhang cleavage by Artemis. We propose that autophosphorylation triggers conformational changes in DNA-PK that enhance Artemis cleavage at single-strand to double-strand DNA junctions. These findings demonstrate that DNA-PK autophosphorylation regulates Artemis access to DNA ends, providing insight into the mechanism of Artemis mediated DNA end processing.
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PMID:DNA-PK autophosphorylation facilitates Artemis endonuclease activity. 1687 98

Primary immunodeficiency disorders (PID) are a heterogeneous group of diseases, characterized by an increased susceptibility to infections. A total of 930 patients (573 males and 357 females) are registered in Iranian PID Registry (IPIDR) during three decades. Predominantly antibody deficiencies were the most common (38.4%), followed by congenital defects of phagocyte number and/or function (28.3%), other well-defined immunodeficiency syndromes (17.7%), combined T- and B-cell immunodeficiencies (11.0%), complement deficiencies (2.4%), and diseases of immune dysregulation (2.3%). Common variable immunodeficiency was the most frequent disorder (20.8%), followed by chronic granulomatous disease, ataxia-telangiectasia, btk deficiency, selective IgA deficiency, and T-B-severe combined immunodeficiency. The frequency of other PID disorders was less than 50 in number (<5%). There is an increasing trend in recognition of more PID in the recent years. Construction of such registry is not only important for its epidemiological aspect but also for its role in increasing the physician's knowledge about such disorders.
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PMID:Frequency and clinical manifestations of patients with primary immunodeficiency disorders in Iran: update from the Iranian Primary Immunodeficiency Registry. 1702 64

Primary immunodeficiency disorders are a heterogeneous group of genetic disorders, with different modes of inheritance, consisting of more than 100 different types. We constructed the DNA banking of primary immunodeficiency disorders for the first time in Iran. The DNA of 31 immunodeficient patients and their families (total of 92 samples) were collected, as the first step for construction of DNA banking. DNA was isolated from whole blood by salting out method. Among our patients, Common variable immunodeficiency was the most common disorder, followed by X-linked agammaglobulinemia, Ataxia-telangiectasia, Chronic granulomatous disease, Severe combined immunodeficiency, Hyper IgM syndromes, and Leukocyte adhesion defects. DNA banking is a useful method for further detection of mutation in immunodeficient patients and prenatal diagnosis for presence or absence of the disorder in the fetus which can be confirmed by molecular genetics testing.
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PMID:DNA banking of primary immunodeficiency disorders in iran. 1723 75

Primary immunodeficiency disorders (PID) are a heterogeneous group of disorders, characterized by an unusual increased susceptibility to various infections. In order to study the frequency of PID in Turk ethnic group of northwestern Iran, this study was performed. Fifty-nine PID patients (36 male and 23 female) with a mean age of 5.3 years (median: 3 years; range: <1 to 22 years) were diagnosed in a 5-year period. The estimated occurrence of PID is about 24 per 100,000 live births in this region. Combined T- and B-cell immunodeficiencies were the most common form of PID in this region, including severe combined immunodeficiency (32.2%), followed by ataxia-telangiectasia (22.0%) and common variable immunodeficiency (18.6%). Recurrent infections were found in almost all our patients, particularly in the respiratory and gastrointestinal systems. Fifteen patients died (25.4%) because of recurrent and severe infections. All dead patients belong to the group of combined T- and B-cell immunodeficiencies. Although PID was previously considered as a group of rare disorders, these is an increased trend in recognition of PID. The high incidence of severe combined immunodeficiency and ataxia-telangiectasia could be due to the genetic backgrounds in the Turk ethnic group.
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PMID:Distribution of primary immunodeficiency diseases in the Turk ethnic group, living in the northwestern Iran. 1758 43

Atypical teratoid/rhabdoid tumor (AT/RT) is an extremely malignant neoplasm in the central nervous system (CNS) which occurs in infancy and childhood. Recent studies suggested that CD133 could be considered a marker for brain cancer stem-like cells (CSCs). However, the role of CD133 in AT/RT has never been investigated. Herein we report the isolation of CD133-positive cells (CD133(+)), found to have the potential to differentiate into three germ layer tissues, from tissues of nine AT/RT patients. The migration/invasion/malignancy and radioresistant capabilities of CD133(+) were significantly augmented when compared to CD133(-). The clinical data showed that the amount of CD133(+) in AT/RTs correlated positively with the degree of resistance to radiation therapy. Using cDNA microarray analysis, the genotoxic-response profiles of CD133(+) and CD133(-) irradiated with 10 Gy ionizing radiation (IR) were analyzed 0.5, 2, 6, 12 and 24 h post-IR. We then validated these microarray data and showed increased phosphorylation after IR of p-ATM, p-RAD17, and p-CHX2 as well as increased expression of BCL-2 protein in CD133(+) compared to CD133(-). Furthermore, we found that CD133(+) can effectively resist IR with cisplatin- and/or TRAIL-induced apoptosis. Immunohistochemical analysis confirmed the up-regulated expression of p-ATM and BCL-2 proteins in IR-treated CD133(+) xenotransgrafts in SCID mice but not in IR-treated CD133(-). Importantly, the effect of IR in CD133(+) transplanted mice can be significantly improved by a combination of BCL-2 siRNA with debromohymenialdisine, an inhibitor of checkpoint kinases. In sum, this is the first report indicating that CD133(+) AT/RT cells demonstrate the characteristics of CSCs. The IR-resistant and anti-apoptotic properties in CD133(+) may reflect the clinical refractory malignancy of AT/RTs and thus the activated p-ATM pathway and BCL-2 expression in CD133(+) could be possible targets to improve future treatment of deadly diseases like AT/RT.
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PMID:Identification of CD133-positive radioresistant cells in atypical teratoid/rhabdoid tumor. 1850 5

Ionizing radiation is a well established carcinogen for human cells. At low doses, radiation exposure mainly results in generation of double strand breaks (DSBs). Radiation-related DSBs could be directly linked to the formation of chromosomal rearrangements as has been proven for radiation-induced thyroid tumors. Repair of DSBs presumably involves two main pathways, non-homologous end joining (NHEJ) and homologous recombination (HR). A number of known inherited syndromes, such as ataxia telangiectasia, ataxia-telangiectasia like-disorder, radiosensitive severe combined immunodeficiency, Nijmegen breakage syndrome, and LIG4 deficiency are associated with increased radiosensitivity and/or cancer risk. Many of them are caused by mutations in DNA repair genes. Recent studies also suggest that variations in the DNA repair capacity in the general population may influence cancer susceptibility. In this paper, we summarize the current status of DNA repair proteins as potential targets for radiation-induced cancer risk. We will focus on genetic alterations in genes involved in HR- and NHEJ-mediated repair of DSBs, which could influence predisposition to radiation-related cancer and thereby explain interindividual differences in radiosensitivity or radioresistance in a general population.
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PMID:Genetic variations in DNA repair genes, radiosensitivity to cancer and susceptibility to acute tissue reactions in radiotherapy-treated cancer patients. 1856 80

Ataxia-telangiectasia (A-T) is a complex multisystem disorder characterized by progressive neurological impairment, variable immunodeficiency and oculo-cutaneous telangiectasia. A-T is a member of chromosomal breakage syndromes and it is caused by a mutation in the ataxia-telangiectasia mutated (ATM) gene. Because of a wide clinical heterogeneity, A-T is often difficult to diagnose in children. We report an unusual case of a 3-year-old boy affected by A-T who presented exclusively with extensive cutaneous granulomatosis and severe combined immunodeficiency, without neurological abnormalities, at the time of diagnosis. This case clearly emphasizes the variable presentation of A-T syndrome and highlights the difficulties in the early diagnosis of A-T. A-T should be considered in children with evidence of combined humoral and cellular immunodeficiency associated with unexplained skin granulomatous lesions, even in the absence of the classic features of this syndrome.
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PMID:Cutaneous granulomatosis and combined immunodeficiency revealing Ataxia-Telangiectasia: a case report. 2038 Jul 44


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