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https://www.readbyqxmd.com/read/28498782/clonal-history-and-genetic-predictors-of-transformation-into-small-cell-carcinomas-from-lung-adenocarcinomas
#1
June-Koo Lee, Junehawk Lee, Sehui Kim, Soyeon Kim, Jeonghwan Youk, Seongyeol Park, Yohan An, Bhumsuk Keam, Dong-Wan Kim, Dae Seog Heo, Young Tae Kim, Jin-Soo Kim, Se Hyun Kim, Jong Seok Lee, Se-Hoon Lee, Keunchil Park, Ja-Lok Ku, Yoon Kyung Jeon, Doo Hyun Chung, Peter J Park, Joon Kim, Tae Min Kim, Young Seok Ju
Purpose Histologic transformation of EGFR mutant lung adenocarcinoma (LADC) into small-cell lung cancer (SCLC) has been described as one of the major resistant mechanisms for epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). However, the molecular pathogenesis is still unclear. Methods We investigated 21 patients with advanced EGFR-mutant LADCs that were transformed into EGFR TKI-resistant SCLCs. Among them, whole genome sequencing was applied for nine tumors acquired at various time points from four patients to reconstruct their clonal evolutionary history and to detect genetic predictors for small-cell transformation...
May 12, 2017: Journal of Clinical Oncology: Official Journal of the American Society of Clinical Oncology
https://www.readbyqxmd.com/read/28479091/family-wide-comparative-analysis-of-cytidine-and-methylcytidine-deamination-by-eleven-human-apobec-proteins
#2
Fumiaki Ito, Yang Fu, Shen-Chi A Kao, Hanjing Yang, Xiaojiang S Chen
APOBECs are a family of cytidine deaminases involved in various important biological processes such as antibody diversification/maturation, restriction of viral infection, and generation of somatic mutations. Catalytically active APOBEC proteins execute their biological functions mostly through deaminating cytosine (C) to uracil on ssDNA/RNA. Activation-induced cytidine deaminase (AID), one of the APOBEC members, was reported to deaminate methylated cytosine (mC) on DNA and this mC deamination was proposed to be involved in demethylation of mC for epigenetic regulation...
May 4, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28472485/apobec3a-efficiently-deaminates-methylated-but-not-tet-oxidized-cytosine-bases-in-dna
#3
Emily K Schutsky, Christopher S Nabel, Amy K F Davis, Jamie E DeNizio, Rahul M Kohli
AID/APOBEC family enzymes are best known for deaminating cytosine bases to uracil in single-stranded DNA, with characteristic sequence preferences that can produce mutational signatures in targets such as retroviral and cancer cell genomes. These deaminases have also been proposed to function in DNA demethylation via deamination of either 5-methylcytosine (mC) or TET-oxidized mC bases (ox-mCs), which include 5-hydroxymethylcytosine, 5-formylcytosine and 5-carboxylcytosine. One specific family member, APOBEC3A (A3A), has been shown to readily deaminate mC, raising the prospect of broader activity on ox-mCs...
May 2, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28439266/a-novel-regulator-of-activation-induced-cytidine-deaminase-apobecs-in-immunity-and-cancer-schr%C3%A3-dinger-s-catalytic-pocket
#4
REVIEW
Justin J King, Mani Larijani
Activation-induced cytidine deaminase (AID) and its relative APOBEC3 cytidine deaminases boost immune response by mutating immune or viral genes. Because of their genome-mutating activities, AID/APOBECs are also drivers of tumorigenesis. Due to highly charged surfaces, extensive non-specific protein-protein/nucleic acid interactions, formation of polydisperse oligomers, and general insolubility, structure elucidation of these proteins by X-ray crystallography and NMR has been challenging. Hence, almost all available AID/APOBEC structures are of mutated and/or truncated versions...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28436987/genomic-consequences-of-aberrant-dna-repair-mechanisms-stratify-ovarian-cancer-histotypes
#5
Yi Kan Wang, Ali Bashashati, Michael S Anglesio, Dawn R Cochrane, Diljot S Grewal, Gavin Ha, Andrew McPherson, Hugo M Horlings, Janine Senz, Leah M Prentice, Anthony N Karnezis, Daniel Lai, Mohamed R Aniba, Allen W Zhang, Karey Shumansky, Celia Siu, Adrian Wan, Melissa K McConechy, Hector Li-Chang, Alicia Tone, Diane Provencher, Manon de Ladurantaye, Hubert Fleury, Aikou Okamoto, Satoshi Yanagida, Nozomu Yanaihara, Misato Saito, Andrew J Mungall, Richard Moore, Marco A Marra, C Blake Gilks, Anne-Marie Mes-Masson, Jessica N McAlpine, Samuel Aparicio, David G Huntsman, Sohrab P Shah
We studied the whole-genome point mutation and structural variation patterns of 133 tumors (59 high-grade serous (HGSC), 35 clear cell (CCOC), 29 endometrioid (ENOC), and 10 adult granulosa cell (GCT)) as a substrate for class discovery in ovarian cancer. Ab initio clustering of integrated point mutation and structural variation signatures identified seven subgroups both between and within histotypes. Prevalence of foldback inversions identified a prognostically significant HGSC group associated with inferior survival...
April 24, 2017: Nature Genetics
https://www.readbyqxmd.com/read/28433662/iron-and-thiol-redox-signaling-in-cancer-an-exquisite-balance-to-escape-ferroptosis
#6
REVIEW
Shinya Toyokuni, Fumiya Ito, Kyoko Yamashita, Yasumasa Okazaki, Shinya Akatsuka
Epidemiological data indicate a constant worldwide increase in cancer mortality, although the age of onset is increasing. Recent accumulation of genomic data on human cancer via next-generation sequencing confirmed that cancer is a disease of genome alteration. In many cancers, the Nrf2 transcription system is activated via mutations either in Nrf2 or Keap1 ubiquitin ligase, leading to persistent activation of the genes with antioxidative functions. Furthermore, deep sequencing of passenger mutations is clarifying responsible cancer causative agent(s) in each case, including aging, APOBEC activation, smoking and UV...
April 19, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28419182/molecular-classification-of-pulmonary-sarcomatoid-carcinomas-suggests-new-therapeutic-opportunities
#7
N Pécuchet, T Vieira, N Rabbe, M Antoine, H Blons, J Cadranel, P Laurent-Puig, M Wislez
Background: Pulmonary sarcomatoid carcinoma (SC) is a rare disease with poor prognosis and with strong inter- and intratumor heterogeneity. However, molecular classification is currently focused on activating MET mutations. We sought to better characterize the molecular diversity of SC using mutational signatures that reflect different mutational processes, such as tobacco-associated adducts (signature 4), BRCA1/BRCA2 deficiency (signature 3) or APOBEC enzyme deamination (signatures 2&13)...
April 13, 2017: Annals of Oncology: Official Journal of the European Society for Medical Oncology
https://www.readbyqxmd.com/read/28405512/high-expression-of-pd-1-ligands-is-associated-with-kataegis-mutational-signature-and-apobec3-alterations
#8
Amélie Boichard, Igor F Tsigelny, Razelle Kurzrock
Immunotherapy with checkpoint inhibitors, such as antibodies blocking the programmed cell-death receptor-1 (PD-1), has resulted in remarkable responses in patients having traditionally refractory cancers. Although response to PD-1 inhibitors correlates with PD-1 ligand (PD-L1 or PD-L2) expression, PD-1 ligand positivity represents only a part of the predictive model necessary for selecting patients predisposed to respond to immunotherapy. We used all genomic, transcriptomic, proteomic and phenotypic data related to 8,475 pan-cancer samples available in The Cancer Genome Atlas (TCGA) and conducted a logistic regression analysis based on a large set of variables, such as microsatellite instability (MSI-H), mismatch repair (MMR) alterations, polymerase δ (POLD1) and polymerase ε (POLE) mutations, activation-induced/apolipoprotein-B editing cytidine deaminases (AID/APOBEC) alterations, lymphocyte markers and mutation burden estimates to determine independent factors that associate with PD-1 ligand overexpression...
2017: Oncoimmunology
https://www.readbyqxmd.com/read/28381554/dna-mutagenic-activity-and-capacity-for-hiv-1-restriction-of-the-cytidine-deaminase-apobec3g-depends-on-whether-dna-or-rna-binds-to-tyrosine-315
#9
Bogdan Polevoda, Rebecca Joseph, Alan E Friedman, Ryan P Bennett, Rebecca Greiner, Thareendra De Zoysa, Ryan A Stewart, Harold C Smith
APOBEC3G (A3G) belongs to the AID/APOBEC protein family of cytidine deaminases (CDA) that bind to nucleic acids. A3G mutates the HIV genome by deamination of dC to dU, leading to accumulation of virus-inactivating mutations. Binding to cellular RNAs inhibits A3G binding to substrate single-stranded (ss) DNA and CDA activity. RNA and ssDNA bind to the same three A3G tryptic peptides (amino acids 181-194, 314-320, and 345-374) that form parts of a continuously exposed protein surface extending from the catalytic domain in the C-terminus of A3G to its N-terminus...
April 5, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28365443/genetic-alterations-as-esophageal-tissues-from-squamous-dysplasia-to-carcinoma
#10
Xi Liu, Min Zhang, Songmin Ying, Chong Zhang, Runhua Lin, Jiaxuan Zheng, Guohong Zhang, Dongping Tian, Yi Guo, Caiwen Du, Yuping Chen, Shaobin Chen, Xue Su, Juan Ji, Wanting Deng, Xiang Li, Shiyue Qiu, Ruijing Yan, Zexin Xu, Yuan Wang, Yuanning Guo, Jiancheng Cui, Shanshan Zhuang, Huan Yu, Qi Zheng, Moshe Marom, Sitong Sheng, Guoqiang Zhang, Songnian Hu, Ruiqiang Li, Min Su
BACKGROUND & AIMS: Esophageal squamous cell carcinoma (ESCC) is most common subtype of esophageal cancer. Little is known about the genetic changes that occur in esophageal cells during development of ESCC. We performed next-generation sequence analyses of esophageal non-tumor, intraepithelial neoplasia (IEN), and ESCC tissues from the same patients to track genetic changes during tumor development. METHODS: We performed whole-genome, exome, or targeted sequence analyses of 227 esophageal tissue samples from 70 patients with ESCC undergoing resection at Shantou University Medical College in China from 2012 through 2015 (no patients had received chemotherapy or radiation therapy); we analyzed normal tissue, tissue with simple hyperplasia, dysplastic tissue (intraepithelial neoplasia, IEN), and ESCC tissues collected from different regions of the esophagus at the same time...
March 29, 2017: Gastroenterology
https://www.readbyqxmd.com/read/28362825/the-preferred-nucleotide-contexts-of-the-aid-apobec-cytidine-deaminases-have-differential-effects-when-mutating-retrotransposon-and-virus-sequences-compared-to-host-genes
#11
Jeffrey Chen, Thomas MacCarthy
The AID / APOBEC genes are a family of cytidine deaminases that have evolved in vertebrates, and particularly mammals, to mutate RNA and DNA at distinct preferred nucleotide contexts (or "hotspots") on foreign genomes such as viruses and retrotransposons. These enzymes play a pivotal role in intrinsic immunity defense mechanisms, often deleteriously mutating invading retroviruses or retrotransposons and, in the case of AID, changing antibody sequences to drive affinity maturation. We investigate the strength of various hotspots on their known biological targets by evaluating the potential impact of mutations on the DNA coding sequences of these targets, and compare these results to hypothetical hotspots that did not evolve...
March 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28334887/avoidance-of-apobec3b-induced-mutation-by-error-free-lesion-bypass
#12
James I Hoopes, Amber L Hughes, Lauren A Hobson, Luis M Cortez, Alexander J Brown, Steven A Roberts
APOBEC cytidine deaminases mutate cancer genomes by converting cytidines into uridines within ssDNA during replication. Although uracil DNA glycosylases limit APOBEC-induced mutation, it is unknown if subsequent base excision repair (BER) steps function on replication-associated ssDNA. Hence, we measured APOBEC3B-induced CAN1 mutation frequencies in yeast deficient in BER endonucleases or DNA damage tolerance proteins. Strains lacking Apn1, Apn2, Ntg1, Ntg2 or Rev3 displayed wild-type frequencies of APOBEC3B-induced canavanine resistance (CanR)...
May 19, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28266028/triggering-of-tlr-3-4-nod2-and-dc-sign-reduces-viral-replication-and-increases-t-cell-activation-capacity-of-hiv-infected-human-dendritic-cells
#13
Sylvain Cardinaud, Alejandra Urrutia, Angeline Rouers, Pierre-Grégoire Coulon, Jérome Kervevan, Clémence Richetta, Anne Bet, Emmanuel A Maze, Martin Larsen, Maria-Candela Iglesias, Victor Appay, Stéphanie Graff-Dubois, Arnaud Moris
A variety of signals influence the capacity of dendritic cells (DCs) to mount potent antiviral cytotoxic T-cell (CTL) responses. In particular, innate immune sensing by pathogen recognition receptors, such as TLR and C-type lectines, influences DC biology and affects their susceptibility to HIV infection. Yet, whether the combined effects of PPRs triggering and HIV infection influence HIV-specific (HS) CTL responses remain enigmatic. Here, we dissect the impact of innate immune sensing by pathogen recognition receptors on DC maturation, HIV infection, and on the quality of HS CTL activation...
May 2017: European Journal of Immunology
https://www.readbyqxmd.com/read/28260788/apobec-signature-mutation-generates-an-oncogenic-enhancer-that-drives-lmo1-expression-in-t-all
#14
Z Li, B J Abraham, A Berezovskaya, N Farah, Y Liu, T Leon, A Fielding, S H Tan, T Sanda, A S Weintraub, B Li, S Shen, J Zhang, M R Mansour, R A Young, A T Look
Oncogenic driver mutations are those that provide a proliferative or survival advantage to neoplastic cells, resulting in clonal selection. Although most cancer-causing mutations have been detected in the protein-coding regions of the cancer genome; driver mutations have recently also been discovered within noncoding genomic sequences. Thus, a current challenge is to gain precise understanding of how these unique genomic elements function in cancer pathogenesis, while clarifying mechanisms of gene regulation and identifying new targets for therapeutic intervention...
March 28, 2017: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
https://www.readbyqxmd.com/read/28215840/cytidine-deaminase-apobec3a-induction-in-fallopian-epithelium-after-exposure-to-follicular-fluid
#15
Pavla Brachova, Nehemiah S Alvarez, Bradley J Van Voorhis, Lane K Christenson
OBJECTIVE: Ovarian carcinomas that originate from fallopian epithelial cells are suggested to arise due to repeated exposure to ovulatory follicular fluid (FF). Mechanistic explanation(s) for how this occurs are unknown. Here, we sought to understand if FF exposure to fallopian epithelial cells could induce DNA damage and expression of a known family of DNA mutators, apolipoprotein B mRNA editing enzyme, catalytic polypeptide (APOBEC) cytidine deaminases. METHODS: Follicular fluid and matched patient plasma samples were obtained from donors...
February 16, 2017: Gynecologic Oncology
https://www.readbyqxmd.com/read/28182305/hepatitis-b-virus-covalently-closed-circular-dna-homeostasis-is-independent-of-the-lymphotoxin-pathway-during-chronic-hbv-infection
#16
Marie-Anne Meier, Aleksei Suslov, Sylvia Ketterer, Markus H Heim, Stefan F Wieland
Current treatment options for patients with chronic hepatitis B virus (HBV) infection are not curative as they are not effective in eliminating covalently closed circular DNA (cccDNA). cccDNA is a stable template for HBV transcription in the nucleus of hepatocytes and is thought to be one of the main factors responsible for HBV persistence. Recently, activation of the lymphotoxin beta receptor (LTβR) has been shown to trigger degradation of cccDNA through induction of cytidine deaminases of the APOBEC3 family in HBV cell culture model systems...
February 9, 2017: Journal of Viral Hepatitis
https://www.readbyqxmd.com/read/28169999/mechanisms-for-targeted-purposeful-mutation-revealed-in-an-apobec-dna-complex
#17
Emily K Schutsky, Zachary M Hostetler, Rahul M Kohli
No abstract text is available yet for this article.
February 6, 2017: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/28131088/long-term-passage-of-vif-null-hiv-1-in-cd4-t-cells-expressing-sub-lethal-levels-of-apobec-proteins-fails-to-develop-apobec-resistance
#18
Eri Miyagi, Sandra Kao, Miyoshi Fumitaka, Alicia Buckler-White, Ron Plishka, Klaus Strebel
APOBEC3G (A3G) is a cytidine deaminase with potent antiviral activity that is antagonized by Vif. A3G is expressed in a cell type-specific manner and some semi-permissive cells, including A3.01, express A3G but fail to block replication of Vif-null HIV-1. Here we explored the semi-permissive nature of A3.01 cells and found it to be defined exclusively by the levels of A3G. Indeed, minor changes in A3G levels rendered A3.01 cells either fully permissive or non-permissive for Vif-null HIV-1. Our data indicate that A3...
April 2017: Virology
https://www.readbyqxmd.com/read/28117753/risks-at-the-dna-replication-fork-effects-upon-carcinogenesis-and-tumor-heterogeneity
#19
REVIEW
Tony M Mertz, Victoria Harcy, Steven A Roberts
The ability of all organisms to copy their genetic information via DNA replication is a prerequisite for cell division and a biological imperative of life. In multicellular organisms, however, mutations arising from DNA replication errors in the germline and somatic cells are the basis of genetic diseases and cancer, respectively. Within human tumors, replication errors additionally contribute to mutator phenotypes and tumor heterogeneity, which are major confounding factors for cancer therapeutics. Successful DNA replication involves the coordination of many large-scale, complex cellular processes...
January 22, 2017: Genes
https://www.readbyqxmd.com/read/28112728/integrated-genomic-and-molecular-characterization-of-cervical-cancer
#20
(no author information available yet)
Cervical cancer remains one of the leading causes of cancer-related deaths worldwide. Here we report the extensive molecular characterization of 228 primary cervical cancers, one of the largest comprehensive genomic studies of cervical cancer to date. We observed notable APOBEC mutagenesis patterns and identified SHKBP1, ERBB3, CASP8, HLA-A and TGFBR2 as novel significantly mutated genes in cervical cancer. We also discovered amplifications in immune targets CD274 (also known as PD-L1) and PDCD1LG2 (also known as PD-L2), and the BCAR4 long non-coding RNA, which has been associated with response to lapatinib...
March 16, 2017: Nature
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