Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We review the genes and proteins related to the homologous recombinational repair (HRR) pathway that are implicated in cancer through either genetic disorders that predispose to cancer through chromosome instability or the occurrence of somatic mutations that contribute to carcinogenesis. Ataxia telangiectasia (AT), Nijmegen breakage syndrome (NBS), and an ataxia-like disorder (ATLD), are chromosome instability disorders that are defective in the ataxia telangiectasia mutated (ATM), NBS, and Mre11 genes, respectively. These genes are critical in maintaining cellular resistance to ionizing radiation (IR), which kills largely by the production of double-strand breaks (DSBs). Bloom syndrome involves a defect in the BLM helicase, which seems to play a role in restarting DNA replication forks that are blocked at lesions, thereby promoting chromosome stability. The Werner syndrome gene (WRN) helicase, another member of the RecQ family like BLM, has very recently been found to help mediate homologous recombination. Fanconi anemia (FA) is a genetically complex chromosomal instability disorder involving seven or more genes, one of which is BRCA2. FA may be at least partially caused by the aberrant production of reactive oxidative species. The breast cancer-associated BRCA1 and BRCA2 proteins are strongly implicated in HRR; BRCA2 associates with Rad51 and appears to regulate its activity. We discuss in detail the phenotypes of the various mutant cell lines and the signaling pathways mediated by the ATM kinase. ATM's phosphorylation targets can be grouped into oxidative stress-mediated transcriptional changes, cell cycle checkpoints, and recombinational repair. We present the DNA damage response pathways by using the DSB as the prototype lesion, whose incorrect repair can initiate and augment karyotypic abnormalities.
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PMID:Recombinational DNA repair and human disease. 1242 31

Friend leukemia virus (FLV) infection strongly enhances gamma-irradiation-induced apoptosis of hematopoietic cells of C3H hosts leading to a lethal anemia. Experiments using p53 knockout mice with the C3H background have clarified that the apoptosis is p53-dependent and would not be associated with changes of cell populations caused by the infection with FLV. In bone marrow cells of FLV + total body irradiation (TBI)-treated C3H mice, the p53 protein was prominently activated to overexpress p21 and bax suggesting that apoptosis-enhancing mechanisms lay upstream of p53 protein in the signaling pathway. Neither of DNA-dependent protein kinase (DNA-PK)-deficient SCID mice nor ataxia telangiectasia mutated (ATM) gene knockout mice with the C3H background exhibited a remarkable enhancement of apoptosis or p53 activation on FLV + TBI-treatment indicating that DNA-PK and ATM were both essential. ATM appeared necessary for introducing DNA damage-induced apoptosis, while DNA-PK enhanced p53-dependent apoptosis under FLV-infection. Surprisingly, viral envelope protein, gp70, was co-precipitated with DNA-PK but not with ATM in FLV + TBI-treated C3H mice. These results indicated that FLV-infection enhances DNA damage-induced apoptosis via p53 activation and that DNA-PK, in association with gp70, might play critical roles in modulating the signaling pathway.
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PMID:DNA-dependent protein kinase enhances DNA damage-induced apoptosis in association with Friend gp70. 1566 Dec 67

The Fanconi anemia (FA) pathway maintains genomic stability in replicating cells. Some sporadic breast, ovarian, pancreatic, and hematological tumors are deficient in FA pathway function, resulting in sensitivity to DNA-damaging agents. FA pathway dysfunction in these tumors may result in hyperdependence on alternative DNA repair pathways that could be targeted as a treatment strategy. We used a high-throughput siRNA screening approach that identified ataxia telangiectasia mutated (ATM) as a critical kinase for FA pathway-deficient human fibroblasts. Human fibroblasts and murine embryonic fibroblasts deficient for the FA pathway were observed to have constitutive ATM activation and Fancg(-/-)Atm(-/-) mice were found to be nonviable. Abrogation of ATM function in FA pathway-deficient cells resulted in DNA breakage, cell cycle arrest, and apoptotic cell death. Moreover, Fanconi anemia complementation group G- (FANCG-) and FANCC-deficient pancreatic tumor lines were more sensitive to the ATM inhibitor KU-55933 than isogenic corrected lines. These data suggest that ATM and FA genes function in parallel and compensatory roles to maintain genomic integrity and cell viability. Pharmaceutical inhibition of ATM may have a role in the treatment of FA pathway-deficient human cancers.
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PMID:Fanconi anemia pathway-deficient tumor cells are hypersensitive to inhibition of ataxia telangiectasia mutated. 1743 3

Fanconi anemia (FA) predisposes to hematopoietic failure, birth defects, leukemia, and squamous cell carcinoma of the head and neck (HNSCC) and cervix. The FA/BRCA pathway includes 8 members of a core complex and 5 downstream gene products closely linked with BRCA1 or BRCA2. Precancerous lesions are believed to trigger the DNA damage response (DDR), and we focused on the DDR in FA and its putative role as a checkpoint barrier to cancer. In primary fibroblasts with mutations in the core complex FANCA protein, we discovered that basal expression and phosphorylation of ATM (ataxia telangiectasia mutated) and p53 induced by irradiation (IR) or mitomycin C (MMC) were upregulated. This heightened response appeared to be due to increased basal levels of ATM in cultured FANCA-mutant cells, highlighting the new observation that ATM can be regulated at the transcriptional level in addition to its well-established activation by autophosphorylation. Functional analysis of this response using gamma-H2AX foci as markers of DNA double-stranded breaks (DSBs) demonstrated abnormal persistence of only MMC- and not IR-induced foci. Thus, we describe a processing defect that leads to general DDR upregulation but specific persistence of DNA crosslinker-induced damage response foci. Underscoring the significance of these findings, we found resistance to DNA crosslinker-induced cell cycle arrest and apoptosis in a TP53-mutant, patient-derived HNSCC cell line, whereas a lymphoblastoid cell line derived from this same individual was not mutated at TP53 and retained DNA crosslinker sensitivity. Our results suggest that cancer in FA may arise from selection for cells that escape from a chronically activated DDR checkpoint.
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PMID:Upregulated ATM gene expression and activated DNA crosslink-induced damage response checkpoint in Fanconi anemia: implications for carcinogenesis. 1822 51

Cells deficient in ataxia telangiectasia mutated (ATM) are hypersensitive to ionizing radiation and other anti-cancer agents that induce double-strand DNA breaks. ATM inhibitors may therefore sensitize cancer cells to these agents. Some cancers may also have underlying genetic defects predisposing them to an ATM inhibitor monotherapy response. We have conducted a genome-wide CRISPR screen to identify genetic vulnerabilities that sensitize lung cancer cells to ATM inhibitors. Knockout of genes in the Fanconi anemia (FA)/BRCA pathway results in hypersensitivity to the ATM inhibitor M3541. Knockdown of either an FA gene or of ATM results in reduced double-strand break end resection, enhanced non-homologous end joining (NHEJ) repair, and decreased homologous recombination repair. Knockout of both the FA/BRCA pathway and ATM strongly inhibits end resection and generates toxic levels of NHEJ, thereby elucidating a mechanism of cellular death by synthetic lethality. ATM inhibitors may therefore be useful for the treatment of tumors with a defective FA/BRCA pathway.
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PMID:Cooperation of the ATM and Fanconi Anemia/BRCA Pathways in Double-Strand Break End Resection. 3207 72

Use of adjuvant chemotherapy has improved survival for many patients with breast cancer. Unfortunately, such treatment can come at a price, in particular, malignancies. We present a case of a 36-year-old woman with heterozygous mutations in the ataxia telangiectasia mutated (ATM) gene who was admitted to the hospital for fatigue and diffusely scattered bruises. She was diagnosed with invasive ductal carcinoma of the left breast and had bilateral mastectomy with axillary node clearance followed by adjuvant chemotherapy 3 years prior. Her vitals were stable. Lab tests revealed thrombocytopenia, leukocytosis, and anemia. Peripheral blood smear and bone marrow biopsy revealed numerous myeloblasts. After flow cytometry and FISH analysis were performed, a diagnosis of therapy-related acute myeloid leukemia (t-AML) was made. The patient was treated with induction chemotherapy and a bone marrow biopsy revealed residual disease. Re-induction therapy was given and a bone marrow biopsy revealed complete remission. She subsequently received an allogenic stem cell transplant and was cured. Her treatment course was uncomplicated. We raise the question as to whether certain chemotherapy agents should be avoided in patients with mutations in DNA repair genes. Furthermore, it is essential for physicians to educate patients on the risk of secondary malignancies arising from chemotherapeutic treatment.
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PMID:A Case of Therapy-Related Acute Myeloid Leukemia in a Patient With Heterozygous Mutations in the Ataxia Telangiectasia Mutated Gene. 3230 Apr 1