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1.
Blood ; 124(25): 3768-71, 2014 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-25349176

RESUMO

The spectrum of cutaneous CD30-positive lymphoproliferative disorders (LPDs) includes lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Chromosomal translocations targeting tyrosine kinases in CD30-positive LPDs have not been described. Using whole-transcriptome sequencing, we identified a chimeric fusion involving NPM1 (5q35) and TYK2 (19p13) that encodes an NPM1-TYK2 protein containing the oligomerization domain of NPM1 and an intact catalytic domain in TYK2. Fluorescence in situ hybridization revealed NPM1-TYK2 fusions in 2 of 47 (4%) primary cases of CD30-positive LPDs and was absent in other mature T-cell neoplasms (n = 151). Functionally, NPM1-TYK2 induced constitutive TYK2, signal transducer and activator of transcription 1 (STAT1), STAT3, and STAT5 activation. Conversely, a kinase-defective NPM1-TYK2 mutant abrogated STAT1/3/5 signaling. Finally, short hairpin RNA-mediated silencing of TYK2 abrogated lymphoma cell growth. This is the first report of recurrent translocations involving TYK2, and it highlights the novel therapeutic opportunities in the treatment of CD30-positive LPDs with TYK2 translocations.


Assuntos
Antígeno Ki-1/genética , Linfoma Anaplásico Cutâneo Primário de Células Grandes/genética , Papulose Linfomatoide/genética , Proteínas Nucleares/genética , Proteínas de Fusão Oncogênica/genética , Neoplasias Cutâneas/genética , TYK2 Quinase/genética , Western Blotting , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Células HEK293 , Humanos , Hibridização in Situ Fluorescente , Antígeno Ki-1/metabolismo , Linfoma Anaplásico Cutâneo Primário de Células Grandes/metabolismo , Linfoma Anaplásico Cutâneo Primário de Células Grandes/patologia , Papulose Linfomatoide/metabolismo , Papulose Linfomatoide/patologia , Mutação , Proteínas Nucleares/metabolismo , Nucleofosmina , Fusão Oncogênica , Proteínas de Fusão Oncogênica/metabolismo , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Fator de Transcrição STAT5/genética , Fator de Transcrição STAT5/metabolismo , Transdução de Sinais/genética , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologia , TYK2 Quinase/metabolismo , Transcriptoma/genética
2.
Am J Clin Pathol ; 161(6): 586-597, 2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38345307

RESUMO

OBJECTIVES: Because of its low frequency in adult populations and clinical and laboratory overlap with hemophagocytic lymphohistiocytosis and other T-cell lymphomas, T-cell/natural killer (NK) cell systemic, chronic, active Epstein-Barr virus (EBV) (T/NK sCAEBV) infection remains underdiagnosed, preventing critical, prompt therapeutic interventions. METHODS: We report a 5-case series that included 2 adult patients with T/NK sCAEBV and 3 additional adult patients with T/NK lymphomas with concomitant systemic EBV infection to review these entities' overlapping diagnostic and clinical features. RESULTS: Approximately 95% of the world population has been infected with EBV during their lifetime, and infection is usually asymptomatic, with symptomatic cases eventually resolving spontaneously. A small subset of immunocompetent patients develops CAEBV, a life-threatening complication resulting from EBV-infected T-cell or NK cell neoplastic lymphocytes. The sites of end-organ damage in T/NK sCAEBV demonstrate pathologic findings such as reactive lymphoid proliferations, making the diagnosis difficult to establish, with the only curative option being an allogeneic hematopoietic stem cell transplant. CONCLUSIONS: This diagnosis is most prevalent in Asia, with few cases reported in Western countries. Adult age is an independent risk factor for poor outcomes, and most cases are diagnosed in pediatric populations.


Assuntos
Infecções por Vírus Epstein-Barr , Humanos , Infecções por Vírus Epstein-Barr/complicações , Infecções por Vírus Epstein-Barr/diagnóstico , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Células Matadoras Naturais/patologia , Células Matadoras Naturais/imunologia , Transtornos Linfoproliferativos/virologia , Transtornos Linfoproliferativos/diagnóstico , Transtornos Linfoproliferativos/patologia , Herpesvirus Humano 4/isolamento & purificação , Idoso , Doença Crônica , Linfoma Extranodal de Células T-NK/patologia , Linfoma Extranodal de Células T-NK/virologia , Linfoma Extranodal de Células T-NK/diagnóstico
3.
Mod Pathol ; 26(5): 640-7, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23411487

RESUMO

Aurora-A is a mitotic kinase implicated in oncogenesis and is known to be overexpressed in B-cell lymphomas and plasma cell myeloma. The expression of Aurora-A kinase (henceforth referred to as Aurora-A) in T-cell lymphomas is not well characterized. In this study, we assessed Aurora-A expression by immunohistochemical analysis in 100 lymphomas encompassing a variety of T-cell lymphomas as categorized in the World Health Organization classification. Aurora-A expression was highest in anaplastic large-cell lymphomas and variably expressed in other types of T-cell lymphomas. In addition, the pattern of Aurora-A expression was predominantly cytoplasmic in ALK-positive anaplastic large-cell lymphoma and was nuclear in ALK-negative anaplastic large-cell lymphoma and other T-cell lymphomas, suggesting altered biochemical mechanisms of Aurora-A nuclear transport in ALK-positive anaplastic large-cell lymphoma. Reverse transcriptase-PCR analysis showed that Aurora-A is more highly expressed in ALK-positive anaplastic large-cell lymphoma than in ALK-negative anaplastic large-cell lymphoma, and is relatively lower in peripheral T-cell lymphomas. Using western blot analysis and the DEL cell line (derived from ALK-positive anaplastic large-cell lymphoma), we showed that Aurora-A expression is decreased after treatment with either MYC or MEK inhibitors, consistent with the MYC and MAP kinase signaling pathways being involved in driving Aurora-A expression; the greatest decrease was observed after MYC inhibition. These findings provide insights into the possible importance of Aurora-A overexpression in anaplastic large-cell lymphoma pathogenesis, and also suggest that Aurora-A inhibition could be a potential therapeutic approach for patients with anaplastic large-cell lymphoma.


Assuntos
Aurora Quinase A/biossíntese , Linfoma de Células T/enzimologia , Aurora Quinase A/análise , Western Blotting , Linhagem Celular Tumoral , Humanos , Imuno-Histoquímica , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa
4.
Case Reports Hepatol ; 2020: 6901514, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32884850

RESUMO

Hemophagocytic lymphohistiocytosis (HLH) is a rare condition characterized by a pathologic immune dysregulation resulting in extreme inflammation. Clinical manifestations are varied but can include severe multiorgan failure and death. HLH has been associated with malignancies, autoimmune diseases, and infections, such as histoplasmosis. Histoplasmosis commonly has subclinical manifestations but can also present in its disseminated form. We present the case of an immunocompromised patient with worsening liver function caused by hepatic histoplasmosis that later triggered HLH with severe multiorgan dysfunction.

5.
Blood Adv ; 3(11): 1778-1787, 2019 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-31186254

RESUMO

High-risk lymphomas (HRLs) are associated with dismal outcomes and remain a therapeutic challenge. Recurrent genetic and molecular alterations, including c-myc expression and aurora A kinase (AAK) and polo-like kinase-1 (PLK1) activation, promote cell proliferation and contribute to the highly aggressive natural history associated with these lymphoproliferative disorders. In addition to its canonical targets regulating mitosis, the AAK/PLK1 axis directly regulates noncanonical targets, including c-myc. Recent studies demonstrate that HRLs, including T-cell lymphomas and many highly aggressive B-cell lymphomas, are dependent upon the AAK/PLK1 axis. Therefore, the AAK/PLK1 axis has emerged as an attractive therapeutic target in these lymphomas. In addition to reviewing these recent findings, we summarize the rationale for targeting AAK/PLK1 in high-risk and c-myc-driven lymphoproliferative disorders.


Assuntos
Aurora Quinase A/metabolismo , Proteínas de Ciclo Celular/metabolismo , Linfoma de Células B/enzimologia , Linfoma de Células T/enzimologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transdução de Sinais , Animais , Humanos , Linfoma de Células B/patologia , Linfoma de Células B/terapia , Linfoma de Células T/patologia , Linfoma de Células T/terapia , Proteínas Proto-Oncogênicas c-myc/metabolismo , Fatores de Risco , Quinase 1 Polo-Like
6.
Appl Immunohistochem Mol Morphol ; 27(3): 180-184, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-28877074

RESUMO

BACKGROUND: Classic Hodgkin lymphoma (CHL) and nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) are clinically distinct entities, with different prognostic and treatment implications. In addition, several large B-cell lymphomas and some T-cell lymphomas can mimic CHL. Differentiating these entities from CHL is crucial for ensuring appropriate therapy. GATA3 is a T-cell transcription factor involved in T-cell maturation and has been previously shown to be overexpressed in CHL cells via gene expression profiling. We investigated the utility of GATA3 immunostain in differentiating CHL from NLPHL and other mimicking entities. MATERIALS AND METHODS: We accrued 17 NLPHLs, 49 CHLs [23 nodular sclerosis (NS), 3 syncytial variants, 3 lymphocyte rich and 13 mixed cellularity types], 4 primary mediastinal large B-cell lymphomas (PMBLs), 2 Epstein-Barr virus (EBV) positive diffuse large B-cell lymphomas (DLBCLs) (EBV+LBCLs), 2 T-cell/histiocyte-rich large B-cell lymphomas (TCHRBCLs), 1 gray zone lymphoma, and 2 tissue microarrays consisting of 72 DLBCLs. One slide from each was stained with GATA3 and percent positive tumor cells and intensity of nuclear expression was semiquantitatively graded independently by 2 board certified hematopathologists. RESULTS: GATA3 was positive in 80% of CHLs. Both percent positivity and intensity of staining varied greatly. Syncytial variant of NS subtype showed the highest positivity rate (3/3; 100%), followed by NS (20/23; 87%), mixed cellularity (9/13; 70%), and lymphocyte rich (2/3; 67%). GATA3 was negative in all NLPHLs, EBV+LBCLs, TCRBCLs, and DLBCLs stained. The single gray zone lymphoma and 3/4 PMBLs were positive. CONCLUSIONS: Nuclear expression of GATA3 can be used to delineate CHL from NLPHL. GATA3 positivity effectively excludes NLPHL with 100% negative predictive value. However, as 20% of CHL can be negative for GATA3, CHL cannot be ruled out with negative GATA3. Additional findings include GATA3 positivity among PMBLs, whereas all 72 DLBCLs were negative for GATA3. This finding further highlights similarities between CHL and PMBL.


Assuntos
Fator de Transcrição GATA3/metabolismo , Doença de Hodgkin , Linfoma Difuso de Grandes Células B , Neoplasias do Mediastino , Proteínas de Neoplasias/metabolismo , Adulto , Idoso , Diagnóstico Diferencial , Feminino , Doença de Hodgkin/diagnóstico , Doença de Hodgkin/metabolismo , Doença de Hodgkin/patologia , Humanos , Imuno-Histoquímica , Linfoma Difuso de Grandes Células B/diagnóstico , Linfoma Difuso de Grandes Células B/metabolismo , Linfoma Difuso de Grandes Células B/patologia , Masculino , Neoplasias do Mediastino/diagnóstico , Neoplasias do Mediastino/metabolismo , Neoplasias do Mediastino/patologia , Pessoa de Meia-Idade , Coloração e Rotulagem
7.
Mod Pathol ; 21(12): 1428-35, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18931650

RESUMO

Aurora-A kinase is a cell-cycle-regulating kinase required for chromosomal segregation. Overexpression of Aurora-A kinase has been shown to correlate with tumor proliferation and chromosomal instability. We investigated Aurora-A kinase expression in peripheral blood and bone marrow of 47 chronic lymphocytic leukemia patients and 20 age-matched hematologically healthy subjects. Western blot analysis showed significantly higher Aurora-A levels in chronic lymphocytic leukemia (42 of 47) compared with lymphocytes of healthy subjects. However, Aurora-A mRNA expression in three chronic lymphocytic leukemia patients was similar to or lower than that of healthy control subjects. In 28 of 42 chronic lymphocytic leukemia patients with elevated Aurora-A kinase expression, one or more chromosomal abnormalities were detected, including trisomy 12 in 9 patients and deletion of the ataxia telangiectasia-mutated gene in 9 patients. Aurora-A was also detected in all (100%) chronic lymphocytic leukemia cases by immunohistochemistry, with a nuclear staining pattern. The larger prolymphocytes and paraimmunoblasts showed stronger Aurora-A kinase expression than did small lymphocytes. In contrast, normal bone marrow reactive lymphocytes were negative for Aurora-A with positive histiocytes and immature myeloid cells. Immunostaining for acetylated histone H3 showed a nuclear pattern in all 38 chronic lymphocytic leukemia cases and double labeling showed coexpression of acetylated histone H3 and Aurora-A. In summary, Aurora-A kinase is overexpressed in chronic lymphocytic leukemia cells. The expression of acetylated histone H3 suggests that Aurora-A kinase may be active (functional). Thus, Aurora-A kinase overexpression in chronic lymphocytic leukemia may be involved in the genesis of chromosomal abnormalities and is a potential target for therapeutic intervention.


Assuntos
Leucemia Linfocítica Crônica de Células B/enzimologia , Proteínas Serina-Treonina Quinases/biossíntese , Acetilação , Adulto , Idoso , Idoso de 80 Anos ou mais , Aurora Quinases , Western Blotting , Núcleo Celular/enzimologia , Aberrações Cromossômicas , Feminino , Citometria de Fluxo , Histonas/metabolismo , Humanos , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/patologia , Masculino , Pessoa de Meia-Idade , RNA Mensageiro/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína Supressora de Tumor p53/metabolismo
8.
Am J Clin Pathol ; 129(5): 714-22, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18426730

RESUMO

We compared the morphologic findings of different types of marginal zone B-cell lymphoma (MZL) involving the bone marrow (BM), including 18 splenic (SMZL), 6 extranodal (mucosa-associated lymphoid tissue lymphoma), and 6 nodal cases. The median percentage of BM involvement was 15%, and multiple overlapping patterns of infiltration were observed in all MZL types. The most frequent patterns were nodular (87%) and interstitial (63%). A focal sinusoidal pattern of involvement was found in one third of SMZLs and rarely in MALT lymphoma. Germinal centers (GCs) were uncommon in routinely stained BM biopsy sections and were observed only in SMZL. However, antibodies specific for CD21 and CD23 highlighted follicular dendritic cells in most MZLs of all types. MZLs cannot be distinguished from each other by examining BM sections alone. However, a sinusoidal pattern or presence of GCs is suggestive of SMZL. Furthermore, correlation with the CBC count can further enhance the reliability of diagnosing SMZL.


Assuntos
Medula Óssea/patologia , Linfoma de Zona Marginal Tipo Células B/classificação , Linfoma de Zona Marginal Tipo Células B/patologia , Adulto , Idoso , Biomarcadores Tumorais/análise , Feminino , Citometria de Fluxo , Humanos , Imuno-Histoquímica , Imunofenotipagem , Masculino , Pessoa de Meia-Idade
9.
Am J Clin Pathol ; 150(5): 393-405, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30052721

RESUMO

OBJECTIVES: To assess bone marrow (BM) sampling in academic medical centers. METHODS: Data from 6,374 BM samples obtained in 32 centers in 2001 and 2011, including core length (CL), were analyzed. RESULTS: BM included a biopsy (BMB; 93%) specimen, aspirate (BMA; 92%) specimen, or both (83%). The median (SD) CL was 12 (8.5) mm, and evaluable marrow was 9 (7.6) mm. Tissue contraction due to processing was 15%. BMB specimens were longer in adults younger than 60 years, men, and bilateral, staging, and baseline samples. Only 4% of BMB and 2% of BMB/BMA samples were deemed inadequate for diagnosis. BM for plasma cell dyscrasias, nonphysician operators, and ancillary studies usage increased, while bilateral sampling decreased over the decade. BM-related quality assurance programs are infrequent. CONCLUSIONS: CL is shorter than recommended and varies with patient age and sex, clinical circumstances, and center experience. While pathologists render diagnoses on most cases irrespective of CL, BMB yield improvement is desirable.


Assuntos
Doenças da Medula Óssea/patologia , Medula Óssea/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia com Agulha de Grande Calibre , Doenças da Medula Óssea/diagnóstico , Exame de Medula Óssea/normas , Canadá , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Estados Unidos , Adulto Jovem
11.
Oncotarget ; 8(70): 114474-114480, 2017 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-29383095

RESUMO

Survival following anthracycline-based chemotherapy remains poor among patients with most T-cell lymphoproliferative disorders. This may be attributed, at least in part, to cell-autonomous mechanisms of chemotherapy resistance observed in these lymphomas, including the loss of important tumor suppressors and the activation of signaling cascades that culminate in the expression and activation of transcription factors promoting cell growth and survival. Therefore, the identification of novel therapeutic targets is needed. In an effort to identify novel tumor dependencies, we performed a loss-of-function screen targeting ≈500 kinases and identified polo-like kinase 1 (PLK-1). This kinase has been implicated in the molecular cross-talk with important oncogenes, including c-Myc, which is itself an attractive therapeutic target in subsets of T-cell lymphomas and in high-grade ("double hit") diffuse large B-cell lymphomas. We demonstrate that PLK-1 expression is prevalent among these aggressive lymphomas and associated with c-myc expression. Importantly, PLK-1 inhibtion with the PLK-1 inhibitor volasertib significantly reduced downstream c-myc phosphorylation and impaired BRD4 binding to the c-myc gene, thus inhibiting c-myc transcription. Therefore, volasertib led to a nearly complete loss of c-myc expression in cell lines and tumor xenografts, induced apoptosis, and thus warrants further investigation in these aggressive lymphomas.

12.
Am J Clin Pathol ; 145(4): 514-23, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27124945

RESUMO

OBJECTIVES: We evaluated the prognostic impact of cell-of-origin classification as well as intratumoral regulatory T cells (Tregs), macrophages, and microvessel density (MVD) on 115 patients (74 in the training set and 41 in the validation set) diagnosed with de novo diffuse large B-cell lymphoma (DLBCL) and uniformly treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy. METHODS: The prognostic impact of Tregs, macrophages, and MVD was evaluated using FOXP3, CD68, and CD34 immunohistochemical stains, respectively. In addition, we designed a scoring system where 1 point was awarded per each adverse prognostic factor, including non-germinal center B-cell-like subtype, FOXP3 17% or more, CD68 less than 2%, and MVD less than 800 vessels/mm(2) RESULTS: Although only MVD was statistically significant on multivariate analysis, the scoring system significantly segregated patients into low- and high-risk groups. Patients having two or more adverse prognostic factors (high-risk group) demonstrated significantly worse event-free and progression-free survivals in the training set and event-free survival in the validation set. CONCLUSIONS: The concomitant evaluation of cell of origin along with tumor microenvironment components identifies patients with DLBCL treated with R-CHOP chemotherapy portraying a worse prognosis.


Assuntos
Linfoma Difuso de Grandes Células B/tratamento farmacológico , Linfoma Difuso de Grandes Células B/patologia , Microambiente Tumoral , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Monoclonais Murinos , Protocolos de Quimioterapia Combinada Antineoplásica , Área Sob a Curva , Biomarcadores Tumorais/análise , Ciclofosfamida , Intervalo Livre de Doença , Doxorrubicina , Feminino , Humanos , Imuno-Histoquímica , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Prednisona , Prognóstico , Modelos de Riscos Proporcionais , Curva ROC , Rituximab , Sensibilidade e Especificidade , Análise Serial de Tecidos , Microambiente Tumoral/imunologia , Vincristina , Adulto Jovem
13.
Case Rep Pathol ; 2015: 380451, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26819793

RESUMO

Blast phase in chronic myelogenous leukemia (CML) has rarely been reported to involve extramedullary sites like skin, lymph nodes, and central nervous system. Clinical history, characteristic hematologic findings (elevated leukocyte counts, myelocytic predominance, and basophilia), and Philadelphia chromosome are of high diagnostic significance especially in isolated extramedullary presentations. We describe a unique case of CML relapse with blast phase involving the eye. A 66-year-old man with a known diagnosis of CML on imatinib and in molecular remission for 3 years presented with a painful blind eye. Histologic examination revealed diffuse involvement of choroid, iris, vitreous humor, and the optic nerve by blast cells. The blasts expressed CD34, aberrant TdT, and a myeloid phenotype (CD13, CD33, and CD117). Fluorescence in situ hybridization (FISH) of vitreous fluid detected BCR-ABL1 gene rearrangement. Additionally, trisomy 8 and gains of 9 and 22 were seen which were not present in the initial diagnostic marrow study 3 years ago. At relapse, the bone marrow, peripheral blood, and the cerebrospinal fluid were not involved by CML. Patient received induction chemotherapy and single dose prophylactic intrathecal methotrexate and was maintained on antityrosine kinase therapy and eventually underwent allogenic stem cell transplantation.

14.
Am J Clin Pathol ; 144(1): 68-77, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26071463

RESUMO

OBJECTIVES: Evaluation of the peripheral blood smear (PBS) is an essential diagnostic test in current medical practice. We aimed to evaluate the use of digital microscopy for the examination of PBS as an option to provide expert interpretation to remote sites and in "on-call" situations. METHODS: We collected 100 Wright-Giemsa-stained PBS slides representing normal and abnormal findings seen at a community-based hospital. Four hematopathologists independently evaluated the cases using conventional light and digital microscopy. RESULTS: When comparing digital vs light microscopy, most of the cellular features evaluated showed at least a moderate degree of agreement in at least three of the reviewers. Discrepancies in final diagnosis were identified in a minority of the cases, most of which were attributed to the poorer resolution of digital microscopy at high magnification (×400). CONCLUSIONS: These results support the limited use of digital microscopy for evaluation and triage of peripheral blood smears as a practical option to obtain expert opinion in locations where experienced staff is not available on site. Our results indicate that while digital microscopy is well suited for basic triage of these blood smears, limitations in quality of imaging at higher magnification as well as large file size may limit its utility in certain settings and situations.


Assuntos
Células Sanguíneas/patologia , Interpretação de Imagem Assistida por Computador/métodos , Microscopia/métodos , Humanos
15.
Radiat Res ; 157(3): 306-11, 2002 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11839093

RESUMO

An essential step in the repair of free radical-mediated DNA strand breaks is the removal of sugar fragments such as phosphoglycolate from the 3' termini. While the abasic endonuclease Ape1 can remove phosphoglycolate from single-strand breaks in double-stranded DNA, an enzyme capable of removing it from 3' overhangs of double-strand breaks has yet to be identified. We therefore tested DNase III, the predominant 3' --> 5' exonuclease in mammalian cell extracts, for possible 3'-phosphoglycolate-removing activity. However, all 3'-phosphoglycolate substrates, as well as a 3'-phosphate substrate, were resistant to DNase III under conditions in which the analogous 3'-hydroxyl substrates were extensively degraded. The DNA end-binding protein Ku (an equimolar mixture of Ku70, now known as G22P1, and Ku86, now known as XRCC5) did not alter the resistance of the 3'-phosphoglycolate substrates, but the protein modulated the susceptibility of 3'-hydroxyl substrates, allowing DNase III to remove a 3' overhang but inhibiting digestion of the double-stranded portion of the substrate.


Assuntos
DNA/metabolismo , Exodesoxirribonucleases/metabolismo , Glicolatos/metabolismo , Animais , Sequência de Bases , Hidrólise
16.
Radiat Res ; 158(3): 327-38, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12175310

RESUMO

Previous work showed that treatment of plateau-phase Chinese hamster ovary cells with the radiomimetic double-strand cleaving agent bleomycin induced very small deletions as well as interchromosomal reciprocal translocations, both of which could be ascribed to errors in end joining of DNA double-strand breaks. In an attempt to assess the possible role of TP53 in suppressing such repair errors, bleomycin-induced mutagenesis at the HPRT locus was examined in immortalized 184B5 human mammary epithelial cells (TP53(+)), and in a TP53-defective derivative, 184B5-E6tfxc6. For both cell lines, the most frequent bleomycin-induced mutations were base substitutions, with no apparent targeting to major bleomycin lesions. However, both lines also sustained single-base deletions that were targeted to expected sites of double-strand breaks, suggesting that they arose by end-joining repair of the breaks. Surprisingly, only a few large deletions or rearrangements, and no interchromosomal events involving the HPRT locus were detected among the mutants. The results suggest that in both cell lines, errors in double-strand break repair resulting in heritable large deletions and rearrangements are rare. Spectral karyotyping of bleomycin-treated 184B5 cells showed that a significant number of translocations were present shortly after bleomycin exposure, but their frequency decreased upon continued culture of the cells. Thus, for these cells, the lack of induced interchromosomal rearrangements can be explained in part by selection against such events as the cells proliferate.


Assuntos
Bleomicina/toxicidade , Mama/citologia , Mutagênese/efeitos dos fármacos , Proteína Supressora de Tumor p53/fisiologia , Sequência de Bases , Bleomicina/farmacologia , Linhagem Celular Transformada/efeitos dos fármacos , Análise Mutacional de DNA , Reparo do DNA , Células Epiteliais/efeitos dos fármacos , Fase G1 , Genes/efeitos dos fármacos , Genes p53 , Hipoxantina Fosforribosiltransferase/genética , Cariotipagem , Dados de Sequência Molecular , Mutação Puntual , Seleção Genética , Deleção de Sequência , Translocação Genética , Proteína Supressora de Tumor p53/deficiência
17.
Environ Mol Mutagen ; 42(4): 279-87, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-14673873

RESUMO

Extracts of Xenopus eggs and of cultured human and hamster cells have the capacity to join nonhomologous DNA ends, and all do so with similar specificity. To examine the formation of repair complexes on DNA under conditions of end joining, end-labeled fragments were incubated with the various extracts and then subjected to DNase-I footprinting. Human and Xenopus extracts produced footprints virtually identical to that of purified DNA-dependent protein kinase holoenzyme (Ku plus DNA-PKcs), with protection of the terminal 28 bp. Extracts of hamster cells were more variable, but usually produced a 16-bp footprint, similar to that of Ku alone. In all cases a 28-bp holoenzyme-like footprint was associated with wortmannin-sensitive end joining, minimal 3'-5' exonucleolytic resection, and a predominance of accurate end-joining products. To determine whether the short segments of DNA occupied by Ku and DNA-PK were sufficient to support end joining, Y-shaped substrates were constructed in which only one arm was available for end joining. A Y substrate with a 31-bp arm bearing a partially cohesive 3' overhang was accurately joined by a Xenopus egg extract, whereas a substrate with a 21-bp arm was not. Surprisingly, a human cell extract did not join the Y substrates at all. The results suggest that differences in wortmannin sensitivity and in the distribution of in vitro end-joining products may be attributable to the variations in the levels of DNA-PKcs in the extracts. In addition, end joining in human extracts appears to involve interactions with significantly longer segments of DNA than the approximately 28 bp occupied by DNA-PK.


Assuntos
DNA Helicases , DNA/química , Proteínas Serina-Treonina Quinases/metabolismo , Androstadienos/farmacologia , Animais , Antígenos Nucleares/química , Células CHO , Extratos Celulares , Cricetinae , Dano ao DNA , Reparo do DNA , Proteína Quinase Ativada por DNA , Proteínas de Ligação a DNA/química , Desoxirribonuclease I/metabolismo , Inibidores Enzimáticos/farmacologia , Humanos , Técnicas In Vitro , Autoantígeno Ku , Proteínas Nucleares , Plasmídeos/metabolismo , Wortmanina , Xenopus
19.
Cardiovasc Pathol ; 19(3): e75-8, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-19144541

RESUMO

SUMMARY: We report herein a unique case of cystic tumor of atrioventricular (AV) node (CTAVN), which, to our knowledge, is the first of its kind diagnosed in an explanted heart specimen and only the fourth diagnosed antemortem. Often, this rare tumor can only be diagnosed by careful gross examination and adequate sampling of AV node region. It is an important differential diagnosis in young patients with syncopal attacks and varying degrees of heart blocks. CONTEXT: CTAVN is a rare, benign tumor. Most cases have been reported in young females (mean age, 38 years). Patients typically present with conduction abnormalities including complete heart block leading to sudden cardiac death. Most cases have been identified at autopsy; no cases to our knowledge have been reported in an explanted heart. DESIGN: A 19 year-old female presented to the cardiac transplant clinic for evaluation of severe congestive heart failure felt to be secondary to postpartum cardiomyopathy. The patient's history was significant for congenital heart block requiring placement of a permanent pacemaker at 12 years of age. At the time of this presentation, electrocardiogram revealed second-degree AV block, and two-dimensional echocardiogram showed lipomatous hypertrophy of the interatrial septum. Seven months later, orthotopic cardiac transplantation was performed. RESULTS: On gross examination, the explanted heart weighed 500 g and had biventricular dilatation. Histologic sections of left and right ventricle revealed myocyte hypertrophy and interstitial fibrosis consistent with dilated cardiomyopathy. Sections from the AV node showed a lesion with morphological features of CTAVN. It was composed of cysts of varying sizes lined by transitional, cuboidal and squamous epithelium. Some cysts were filled with proteinaceous debris that were periodic acid Schiff-positive and diastase resistant. CONCLUSIONS: CTAVN occurs exclusively in the area of the AV node, tricuspid valve, and inferior atrial septum. These lesions are now believed to be endodermal in origin, although mesothelial origin was earlier proposed. We report herein a case of CTAVN, the first of its kind diagnosed in an explanted heart specimen and only the fourth diagnosed antemortem.


Assuntos
Nó Atrioventricular/patologia , Cistos/patologia , Neoplasias Cardíacas/patologia , Cardiomiopatia Dilatada/cirurgia , Eletrocardiografia , Feminino , Bloqueio Cardíaco/congênito , Bloqueio Cardíaco/terapia , Transplante de Coração , Humanos , Marca-Passo Artificial , Gravidez , Complicações na Gravidez/patologia , Complicações na Gravidez/cirurgia , Adulto Jovem
20.
Cancer ; 115(5): 1041-8, 2009 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-19170236

RESUMO

BACKGROUND: It has been demonstrated that the tumor proliferation index has prognostic significance in patients with mantle cell lymphoma (MCL). Patients in most of studies, however, have been treated with relatively traditional chemotherapy regimens. At the authors' institution, patients with MCL received an aggressive chemotherapy regimen: rituximab plus hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone alternating with rituximab plus high-dose methotrexate and cytarabine (R-hyper-CVAD). METHODS: The authors assessed the proliferation rate of MCL using immunohistochemistry and an antibody specific for Ki-67 in 71 untreated patients who subsequently received R-hyper-CVAD. The study group included 59 patients who had classic MCL and 12 patients who had the blastoid variant of MCL. RESULTS: For the entire study group and for the group of patients with classic MCL, a proliferation index of >20% Ki-67-positive cells was correlated significantly with shorter failure-free survival. There was no correlation between the proliferation index and overall survival. CONCLUSIONS: The current results indicated that the proliferation index in patients with MCL predicted prognosis in those who uniformly received the R-hyper-CVAD chemotherapy regimen.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Linfoma de Célula do Manto/tratamento farmacológico , Anticorpos Monoclonais , Anticorpos Monoclonais Murinos , Ciclofosfamida/administração & dosagem , Citarabina/administração & dosagem , Dexametasona/administração & dosagem , Intervalo Livre de Doença , Doxorrubicina/administração & dosagem , Esquema de Medicação , Feminino , Humanos , Antígeno Ki-67/metabolismo , Masculino , Metotrexato/administração & dosagem , Pessoa de Meia-Idade , Prognóstico , Rituximab , Análise de Sobrevida , Vincristina/administração & dosagem
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