Cytogenetic abnormalities in patients with hematological malignancies in Lahore city, Pakistan / Anormalidades citogenéticas em pacientes com neoplasias hematológicas na cidade de Lahore, Paquistão

Abstract Hematological and hematopoietic cells malignancies of the genes and hematopoietic cells are associated with the genetic mutation, often at the chromosomal level. The standard cytogenetic study is widely accepted as one of the main diagnostics and prognostic determinants in patients. Therefore, the current descriptive and cross-sectional study sought to determine the cytogenetic analysis of frequent hematological malignancies in Pakistan. A total of 202 peripheral bone marrow or blood samples from patients with benign and malignant hematological malignancy were taken using a conventional G-banding technique. Among enrolled patients, the mean age was 21.5 years ± 23.4, and gender-wise distribution showed a marked predominance of the male 147 (73%) population compared to the female 55 (27%). Patients in the age group (2-10 years) had the highest frequency, 48 (24%), of hematological neoplasms, followed by age (11-20 years) with 40 (20%). Normal karyotypes (46, XX/46, XY) was found in 51% (n=103) patients. Furthermore, the frequency of complex karyotype was 30 (15%), while normal was seen in 171 (85%) patients. Pre-B Acute Lymphoblastic Leukemia (Pre-B ALL) was the most prevalent malignancy of 66 (33%), followed by Chronic Myelogenous Leukemia (CML) of 41 (20%) and Acute Lymphocytic Leukemia of 29 (14%). Translocation was the most prevalent 50 (25%), followed by hypotriploidy 14 (7%) and monosomy 8 (4%) on chromosome aberration analysis. In addition, t(9:22) translocation was found to be 20 (10%) in CML, with the majority in the age group (31-40 years). This study recommends that karyotyping should be tested frequently in hematological conditions because it may provide insight into the relative chromosomal changes associated with particular malignancies.

Resumo As neoplasias hematológicas e de células hematopoiéticas dos genes e as células hematopoiéticas estão associadas à mutação genética, geralmente em nível cromossômico. O estudo citogenético padrão é amplamente aceito como um dos principais determinantes diagnósticos e prognósticos em pacientes. Portanto, o presente estudo descritivo e transversal buscou determinar a análise citogenética de neoplasias hematológicas frequentes no Paquistão. Um total de 202 amostras de medula óssea periférica ou sangue de pacientes com malignidade hematológica benigna e maligna foi coletado usando uma técnica convencional de banda G. Entre os pacientes inscritos, a média de idade foi de 21,5 anos ± 23,4, e a distribuição por gênero mostrou uma marcada predominância da população masculina de 147 (73%) em comparação com a feminina de 55 (27%). Pacientes na faixa etária (2-10 anos) tiveram a maior frequência, 48 (24%), de neoplasias hematológicas, seguida da idade (11-20 anos) com 40 (20%). Cariótipos normais (46, XX / 46, XY) foram encontrados em 51% (n = 103) dos pacientes. Além disso, a frequência de cariótipo complexo foi de 30 (15%), enquanto normal foi observada em 171 (85%) pacientes. Leucemia linfoblástica aguda pré-B (LLA Pré-B) foi a doença maligna mais prevalente de 66 (33%), seguida por leucemia mieloide crônica (LMC) de 41 (20%) e leucemia linfocítica aguda de 29 (14%). A translocação foi o 50 mais prevalente (25%), seguido por hipotriploidia 14 (7%) e monossomia 8 (4%) na análise de aberração cromossômica. Além disso, a translocação t (9:22) encontrada foi de 20 (10%) na LMC, com a maioria na faixa etária (31-40 anos). Este estudo recomenda que o cariótipo deve ser testado com frequência em condições hematológicas porque pode fornecer informações sobre as alterações cromossômicas relativas associadas a doenças malignas específicas.

Recent Research Progress on CircRNA in Hematological Malignancies--Review / 中国实验血液学杂志

Most hematological tumors have high-grade malignancy and low cure rate, requiring new molecular markers for detection and evaluation. Circular RNAs (circRNAs) are a class of non-coding RNAs with covalently closed-loop structures, which participate in gene transcription and translation by binding to microRNAs and proteins. In recent years, with the deepening research on circRNAs, circRNAs have been found to play an important role in hematological malignancies. In this review, the latest research progress on the function and molecular mechanism of circRNAs in hematological malignancies was systematically summarized, and it was found that circRNAs may be potential new biomarkers and therapeutic targets in hematological malignancies.

Research Progress of Long Non-Coding RNA in Hematological Tumors --Review / 中国实验血液学杂志

Long non-coding RNA (lncRNA) is a hot topic in the field of researching tumor pathogenesis, and the importance in hematologic malignancies has been gradually being elucidated. LncRNA not only regulates hematological tumorigenesis and progression through affecting various biological processes such as cell proliferation, differentiation, pluripotency and apoptosis; moreover, abnormal expression and mutation of lncRNA are closely related to drug resistance and prognosis. Thus lncRNA can be used as novel biomarker and potential therapeutic target for hematological tumors. In this review, we will focus on the latest progress of lncRNA in hematological tumors to provide new ideas for the clinical diagnosis, prognostic evaluation together with research and development of target drugs for hematologic malignancies.

Cytogenetic abnormalities in patients with hematological malignancies in Lahore city, Pakistan / Anormalidades citogenéticas em pacientes com neoplasias hematológicas na cidade de Lahore, Paquistão

Hematological and hematopoietic cells malignancies of the genes and hematopoietic cells are associated with the genetic mutation, often at the chromosomal level. The standard cytogenetic study is widely accepted as one of the main diagnostics and prognostic determinants in patients. Therefore, the current descriptive and cross sectional study sought to determine the cytogenetic analysis of frequent hematological malignancies in Pakistan. A total of 202 peripheral bone marrow or blood samples from patients with benign and malignant hematological malignancy were taken using a conventional G-banding technique. Among enrolled patients, the mean age was 21.5 years ± 23.4, and gender-wise distribution showed a marked predominance of the male 147 (73%) population compared to the female 55 (27%). Patients in the age group (2-10 years) had the highest frequency, 48 (24%), of hematological neoplasms, followed by age (11-20 years) with 40 (20%). Normal karyotypes (46, XX/46, XY) was found in 51% (n=103) patients. Furthermore, the frequency of complex karyotype was 30 (15%), while normal was seen in 171 (85%) patients. Pre-B Acute Lymphoblastic Leukemia (Pre-B ALL) was the most prevalent malignancy of 66 (33%), followed by Chronic Myelogenous Leukemia (CML) of 41 (20%) and Acute Lymphocytic Leukemia of 29 (14%). Translocation was the most prevalent 50 (25%), followed by hypotriploidy 14 (7%) and monosomy 8 (4%) on chromosome aberration analysis. In addition, t(9:22) translocation was found to be 20 (10%) in CML, with the majority in the age group (31-40 years). This study recommends that karyotyping should be tested frequently in hematological conditions because it may provide insight into the relative chromosomal changes associated with particular malignancies.

As neoplasias hematológicas e de células hematopoiéticas dos genes e as células hematopoiéticas estão associadas à mutação genética, geralmente em nível cromossômico. O estudo citogenético padrão é amplamente aceito como um dos principais determinantes diagnósticos e prognósticos em pacientes. Portanto, o presente estudo descritivo e transversal buscou determinar a análise citogenética de neoplasias hematológicas frequentes no Paquistão. Um total de 202 amostras de medula óssea periférica ou sangue de pacientes com malignidade hematológica benigna e maligna foi coletado usando uma técnica convencional de banda G. Entre os pacientes inscritos, a média de idade foi de 21,5 anos ± 23,4, e a distribuição por gênero mostrou uma marcada predominância da população masculina de 147 (73%) em comparação com a feminina de 55 (27%). Pacientes na faixa etária (2-10 anos) tiveram a maior frequência, 48 (24%), de neoplasias hematológicas, seguida da idade (11-20 anos) com 40 (20%). Cariótipos normais (46, XX / 46, XY) foram encontrados em 51% (n = 103) dos pacientes. Além disso, a frequência de cariótipo complexo foi de 30 (15%), enquanto normal foi observada em 171 (85%) pacientes. Leucemia linfoblástica aguda pré-B (LLA Pré-B) foi a doença maligna mais prevalente de 66 (33%), seguida por leucemia mieloide crônica (LMC) de 41 (20%) e leucemia linfocítica aguda de 29 (14%). A translocação foi o 50 mais prevalente (25%), seguido por hipotriploidia 14 (7%) e monossomia 8 (4%) na análise de aberração cromossômica. Além disso, a translocação t (9:22) encontrada foi de 20 (10%) na LMC, com a maioria na faixa etária (31-40 anos). Este estudo recomenda que o cariótipo deve ser testado com frequência em condições hematológicas porque pode fornecer informações sobre as alterações cromossômicas relativas associadas a doenças malignas específicas.

Fanconi anemia gene-associated germline predisposition in aplastic anemia and hematologic malignancies / 医学前沿

Whether Fanconi anemia (FA) heterozygotes are predisposed to bone marrow failure and hematologic neoplasm is a crucial but unsettled issue in cancer prevention and family consulting. We retrospectively analyzed rare possibly significant variations (PSVs) in the five most obligated FA genes, BRCA2, FANCA, FANCC, FANCD2, and FANCG, in 788 patients with aplastic anemia (AA) and hematologic malignancy. Sixty-eight variants were identified in 66 patients (8.38%). FANCA was the most frequently mutated gene (n = 29), followed by BRCA2 (n = 20). Compared with that of the ExAC East Asian dataset, the overall frequency of rare PSVs was higher in our cohort (P = 0.016). BRCA2 PSVs showed higher frequency in acute lymphocytic leukemia (P = 0.038), and FANCA PSVs were significantly enriched in AA and AML subgroups (P = 0.020; P = 0.008). FA-PSV-positive MDS/AML patients had a higher tumor mutation burden, higher rate of cytogenetic abnormalities, less epigenetic regulation, and fewer spliceosome gene mutations than those of FA-PSV-negative MDS/AML patients (P = 0.024, P = 0.029, P = 0.024, and P = 0.013). The overall PSV enrichment in our cohort suggests that heterozygous mutations of FA genes contribute to hematopoietic failure and leukemogenesis.

Chinese Medicine Regulates DNA Methylation to Treat Haematological Malignancies: A New Paradigm of "State-Target Medicine" / 中国结合医学杂志

Aberrant regulation of DNA methylation plays a crucial causative role in haematological malignancies (HMs). Targeted therapy, aiming for DNA methylation, is an effective mainstay of modern medicine; however, many issues remain to be addressed. The progress of epigenetic studies and the proposed theory of "state-target medicine" have provided conditions to form a new treatment paradigm that combines the "body state adjustment" of CM with targeted therapy. We discussed the correlation between Chinese medicine (CM) syndromes/states and DNA methylation in this paper. Additionally, the latest research findings on the intervention and regulation of DNA methylation in HMs, including the core targets, therapy status, CM compounds and active components of the Chinese materia medica were concisely summarized to establish a theoretical foundation of "state-target synchronous conditioning" pattern of integrative medicine for HMs, simultaneously leading a new perspective in clinical diagnosis and therapy.

Citogenética de las hemopatías malignas en la era de la secuenciación / Cytogenetics of malignant hemopathies in the sequencing era

Las neoplasias hematológicas se caracterizan por un gran número y complejidad de alteraciones genéticas, desde la formación de genes de fusión a partir de translocaciones e inversiones cromosómicas hasta mutaciones génicas y alteraciones epigenéticas que han permitido la identificación de nuevos oncogenes y genes supresores de tumores responsables de su etiología. Al abordar el estudio genético de las leucemias se utilizan múltiples técnicas como la citogenética convencional, citogenética molecular (hibridaciónin situ por fluorescencia (FISH), esta última con una mayor sensibilidad, especificidad y rapidez que permiten el diagnóstico, la estratificación pronóstica y seguimiento de la enfermedad. Las técnicas anteriores se integran con técnicas de biología molecular, secuenciación génica, entre otras, que permiten el hallazgo de nuevos marcadores genéticos con una mejor caracterización de las hemopatías malignas y la posibilidad del desarrollo de nuevos fármacos específicos que actúen sobre la diana molecular. El objetivo fue revisar la utilidad de la citogenética y la secuenciación génica en el estudio de la leucemia mieloide aguda y la leucemia linfocítica crónica. Ante las ventajas, desventajas y limitaciones de estas técnicas genéticas es necesario utilizarlas de forma complementaria y nunca excluyente(AU)

Hematological neoplasms are characterized by a large number and great complexity of genetic disorders, from the formation of fusion genes after chromosomal translocations and inversions to gene mutation and epigenetic disorders that have permitted the identification of new oncogenes and tumor-suppressing genes responsible for their etiology. When addressing the genetic study of leukemias, multiple techniques are used, such as conventional cytogenetics, molecular cytogenetics, and fluorescence in situ hybridization (FISH), the latter having the higher degree of sensitivity, specificity and speed, which allow diagnosis, prognostic stratification and follow-up of the disease. The previous techniques are integrated with molecular biology techniques, gene sequencing, among others, which allow discovery of new genetic markers with better characterization of malignant hemopathies and the possibility of developing new specific drugs against the molecular target. The objective was to review the usefulness of cytogenetics and gene sequencing in the study of acute myeloid leukemia and chronic lymphocytic leukemia. Given the advantages, disadvantages and limitations of these genetic techniques, it is necessary to use them in as complementary but never exclusive management ways(AU)

Research Progress of Expression and Clinical Significant of EZH2 in Hematological Malignancies--Review / 中国实验血液学杂志

Enhancer of zeste homolog 2(EZH2) is a histone methyltransferase which regulate gene expression through epigenetic machinery. The abnormal expression of EZH2 has been described in many cancer types. With in-depth study, it was found that EZH2 is involved in the occurrence and development in many kinds of malignant hematologic disease which may play a dual role of oncogenes and tumor suppressor genes. In recent years, the emergence of EZH2 inhibitors provide a new option for the future treatment of hematological malignancies. In this review, the expression and clinical significance of EZH2 in various of hematological tumors were summarized briefly.

Características otorrinolaringológicas en niños con trisomía 21: un estudio de 171 pacientes en el Hospital Infantil de México Federico Gómez / Otolaryngological features in children with trisomy 21: a study of 171 patients at the Hospital Infantil de México Federico Gómez

Resumen Introducción: Los niños con trisomía 21 enfrentan una amplia gama de problemas en la región de la cabeza y el cuello, por lo cual es importante reconocer las manifestaciones otorrinolaringológicas que presentan, así como su apropiado manejo. Métodos: Estudio de serie de casos retrospectivo de pacientes pediátricos con trisomía 21. De cada caso se analizó el espectro de manifestaciones otorrinolaringológicas, el manejo establecido y los resultados. Resultados: Se incluyeron 171 niños. La edad media de la primera valoración por otorrinolaringología en la institución fue de 7.2 ± 4.2 años. Las manifestaciones otológicas más frecuentes fueron la estenosis del conducto auditivo externo y la disfunción de la trompa de Eustaquio. Más de la mitad de los pacientes (63 %) presentaron hipoacusia, principalmente de tipo conductivo bilateral, y hasta el 75 % de los pacientes con afectación otológica requirieron algún procedimiento quirúrgico. Las manifestaciones rinológicas más comunes fueron la rinosinusitis crónica y la rinitis alérgica. La apnea obstructiva del sueño estuvo presente en el 30% de los pacientes. El tratamiento principal fue la amigdalectomía, seguida del tratamiento con dispositivos de presión positiva de la vía aérea. Menos del 5 % de los pacientes presentaron un compromiso laríngeo. Conclusiones: Los pacientes pediátricos con trisomía 21 deben ser remitidos sistemáticamente a una evaluación otorrinolaringológica periódica, debido a la alta incidencia de manifestaciones en esta región. Se deben ofrecer tratamientos oportunos para mejorar su salud y calidad de vida.

Abstract Introduction: Children with trisomy 21 face a wide range of conditions in the head and neck region, for which it is important that physicians are aware and have a strong understanding of the ear, nose, and throat (ENT) disorders, and their management as well. Methods: Retrospective case series of pediatric patients with trisomy 21. The spectrum of otolaryngological manifestations, their management, and outcomes of each case were analysed. Results: One hundred and seventeen pediatric patients were included. The mean age was 7.2 ± 4.2 years. More than half of the patients (63 %) had hearing loss (HL). The most frequent presentation was conductive HL, predominating the mild and bilateral type. The most common otological manifestations found were external ear canal stenosis and Eustachian tube dysfunction. Up to 75 % of the patients with otologic involvement required some surgical procedure. The most common rhinological manifestations were chronic rhinosinusitis and allergic rhinitis. Obstructive sleep apnea (OSA) was present in 30% of all patients, which main treatment was tonsillectomy, followed by continuous positive and biphasic positive airway pressure treatments. Less than 5 % of the patients presented a laryngeal compromise. Conclusions: Pediatric patients with trisomy 21 systematically should be referred to periodic ENT assessment due to the high incidence of manifestations in this region. Timely treatments should be offered in order to improve the health and the quality of life of the patient.

Síndromes de hemopatías mieloides malignas hereditarias / Inherited myeloid malignancy syndromes

La predisposición de algunas familias a padecer hemopatías mieloides malignas ha sido descrita desde hace varias décadas; sin embargo, solo recientemente ha sido posible conocer las bases moleculares de estos síndromes. La importancia de reconocer y diagnosticar la presencia de mutaciones predisponentes de la línea germinal en pacientes con hemopatías malignas y en sus familiares determinó que la Organización Mundial de la Salud (OMS) introdujera esta nueva categoría en su última revisión de la clasificación de las neoplasias malignas y leucemias agudas. Mediante el uso de las modernas técnicas de biología molecular se ha logrado el descubrimiento de mutaciones en diferentes genes que aportan nuevos elementos en el proceso de leucemogénesis, permiten ofrecer consejo genético, una mejor selección del donante de médula ósea y se erigen en la fuente de futuras dianas terapéuticas. En este trabajo se revisan algunos de los síndromes de hemopatías mieloides malignas hereditarias (HMMH) y se enfatiza en la necesidad de realizar una exhaustiva historia clínica personal y familiar que permita un elevado índice de sospecha para el diagnóstico de estas entidades(AU)

The familial predisposition to inherited myeloid malignancies has been described since several decades ago; however, only recently have been possible to known the molecular basis of these syndromes. The importance to recognize and diagnosed predisposing germ line mutations in patients and relatives contributed to the introduction of this new category in the latest update of myeloid neoplasm and acute leukemia by World Health Organization (WHO). The use of modern molecular biology techniques has achieved the discovery of genetic mutations that shed light inside leukemogenesis process, allow offering a genetic counseling, a better donor selection and are the basis of future therapeutics targets. The main hereditary myeloid malignancy syndromes (IMMS) are reviewed, emphasizing the need of exhaustive personal and family clinical history and to have a high suspicion index to diagnose these entities(AU)

Aberrant expression of miRNAs predicts recurrence and survival in stage-II colorectal cancer patients from Egypt

Background: Patients with stage II CRC have a varying survival outcome. Therefore, it is critical to identify prognostic biomarkers that can define more aggressive forms of the disease. We assessed the expression levels of five miRNAs that have been previously addressed in relation to the development and progression of solid and hematological tumors. Methods: We measured the expression levels of miR-21, miR-137, miR-145, miR-320 and miR-498in stage II CRC patients from Egypt (124 tissues and 41 blood samples) by quantitative real time PCR (qPCR). The results were correlated with relevant clinicopathological factors, response to treatment and survival rates of the patients. Results: miR-137, miR-145 and miR-320 were significantly reduced in 39.5%, 48.4% and 52.4%; respectively whereas miR-21 and miR-498 were significantly overexpressed in 48.4% and 40.3% of the CRC tissues compared to the control group. In patients' blood, miR-137, miR-145 and miR-320 were significantly reduced in 46.3%, 46.3% and 51. 2%; respectively whereas mir-21 and miR-498 were significantly overexpressed in 46.3% and 43.9% of the cases, respectively. The concordance between tissue and blood was weak for miR-320 and miR-145 (kappa 40-65%), intermediate for miR-498 and miR-137 (kappa 65-75%) and strong for miR-21 (kappa 75-85%). In univariate analysis performance status, over-expression of miR-21 and miR-498 and reduced miR-137, miR-145, and miR-320 associated significantly with reduced DFS and OS. However, in multivariate analysis, miR-498 and miR-320 were independent prognostic factors for DFS whereas miR-21 was independent prognostic factors for OS. Conclusions: miRNAs play an important role in the development and progression of stage II CRC. A five markers panel (miR-21, miR-498, miR-137, miR-145 and miR-320) can predict recurrence and survival in stage II CRC patients from Egypt (AU)

The Janus Kinase 2 (JAK2) V617F mutation in hematological malignancies in México / La mutación V617F del gen de la cinasa JAK2 en padecimientos hematológicos malignos en México

A new mutation (V617F) affecting the JAK2 gene has been recently described as acquired in patients with myeloproliferative disorders and other myeloid malignancies. Using an amplification refractory mutation system, we investigated this mutation in 70 Mexican mestizo patients with hematological malignancies: 28 cases of acute lymphoblastic leukemia, 17 cases of Phi-positive chronic myelogenous leukemia, 8 patients with acute myelogenous leukemia, 6 patients with chronic lymphocytic leukemia, 6 patients with polycythemia vera (PV), two patients with essential thrombocythemia (ET), one patient with hypereosinophilic syndrome one patient with primary myelofibrosis (MF) and one patient with chronic myelomonocytic leukemia. The mutation was identified in 4 of 6 patients with PV, in one of 2 patients with ET and in the patient with MF. Our data add to the observation that the JAK2 V617F mutation seems to be rather uncommon in myeloid malignancies other than the classic BCR/ABL negative MPD.

Se ha descrito una nueva mutación (V617F) que afecta al gen de la cinasa JAK2 en pacientes con padecimientos mieloproliferativos y otras neoplasias mieloides. Empleando un sistema de amplificación de mutaciones refractarias y reacción en cadena de la polimerasa, investigamos esta mutación en 70 pacientes mestizos mexicanos con neoplasias hematológicas malignas: 28 casos de leucemia aguda linfoblástica, 17 casos de leucemia granulocítica crónica BCR/ABL (+), ocho casos de leucemia aguda mieloblástica, seis casos de leucemia linfocítica crónica, seis casos de policitemia vera (PV), dos casos de trombocitosis primaria (TP), un caso de síndrome hipereosinofílico primario y un caso de mielofibrosis primaria (MF) y un caso de leucemia mielomonocítica crónica. La mutación se identificó en cuatro de seis pacientes con PV, en uno de dos pacientes con TP y en el paciente con MF. Estos datos confirman que esta mutación es infrecuente en neoplasias hematológicas mieloides diferentes a los síndromes mieloproliferativos malignos negativos al BCR/ABL; es probable que esta mutación se convierta en el marcador molecular de la PV.

Molecular hematology. Qualitative to quantitative techniques

Over the last decade molecular diagnostics technology has developed dramatically from the most laborious, time- consuming southern blot methodology through the revolution of polymerase chain reaction PCR technology to the most reliable, fast, and contamination free molecular analyzer, the real-time quantitative-PCR. The Section of Hematology, Department of Pathology and Laboratory Medicine at King Faisal Specialist Hospital and Research Center has shared this experience during the last 10 years with more than 6,546 samples submitted for the analysis of different gene rearrangements, fusion gene transcripts and gene mutations including Ig heavy chain gene rearrangement for B-cell malignancies, T-cell receptor gamma chain gene rearrangement for T-cell malignancies, BCR/ABL-P210 and P190 fusion gene transcripts, for chronic myeloid leukemia and Philadelphia positive acute lymphoblastic leukemia, PML/RARa fusion gene for promyelocytic leukemia, AML1/ETO for acute myeloid leukemia AML-M2 with t8;21, CBFB/MYH11 for AML M4E0 with inv 16, BCL-2 for follicular lymphoma, and BCL-1 for mantle cell lymphoma. Hence, most molecular assays are qualitative in nature, quantitative assays are deemed necessary in the monitoring and follow-up of minimal residual disease in leukemia and lymphoma, and proved in our experience to serve as an essential tool to confirm complete remission CR post-chemotherapy and bone marrow transplantation, and to detect signs of early relapse for proper clinical intervention. In this manuscript, we retrospectively review our experience in molecular hematology and propose our recommended guidelines at King Faisal Specialist Hospital and Research Center

p53 e as hemopatias malignas / p53 and hematological malignancies

p53 é um gene supressor tumoral, que codifica uma fosfoproteína nuclear que desempenha um papel importante no controle do ciclo celular, no reparo do DNA e na indução da apoptose. Em condições de stress, particularmente por indução de dano no DNA, a proteína p53 bloqueia o ciclo celular, permitindo dessa forma o reparo do DNA ou promovendo a apoptose. Estas funções são efetuadas pela capacidade transcricional da proteína p53 que ativa uma série de genes envolvidos na regulação do ciclo celular. A forma mutada da p53 é incapaz de controlar a proliferação celular, resultando em reparo ineficiente do DNA e na emergência de célulasgeneticamente instáveis. As alterações mais comuns nas neoplasias são mutações pontuais dentro das seqüências codificantes deste gene. Nas hemopatias malignas, estas mutações, freqüentemente do tipo pontuais, têm sido observadas com menor ocorrência do que em tumores sólidos. Nas neoplasias hematológicas estas alterações são mais observadas na crise blástica da leucemia mielóide crônica, progressão da síndrome mielodisplásica para leucemia mielóide aguda, na transformação do linfoma folicular para linfoma de alto grau, na evolução da leucemia linfóide crônica para síndrome de Richter e recorrência de leucemias agudas. Esta revisão tem como objetivo avaliar as alterações do gene p53 nas hemopatias malignas e discutir o significado clínico destas alterações genéticas na patogenia e prognóstico nessasneoplasias.

Fas-mediated apoptosis and expression of related genes in human malignant hematopoietic cells

Fas transduces apoptotic signals upon cross-linking with the Fas ligand (FasL), which is experimentally replaced by agonistic anti-Fas monoclonal antibodies (mAb). Of eight human malignant hematopoietic cell lines (HL-60, KG-1, THP-1, K562, U937, Jurkat, IM-9, RPMI-8226) examined by flow cytometric analysis, all, except K562, were found to be positive for surface Fas antigen. However, despite surface Fas expression, the agonistic anti-Fas mAb (7C11) induced apoptosis in only three of seven Fas-expressing cell lines (KG-1, Jurkat and IM-9). This Fas-resistance did not correlated with high levels of mRNA either for DcR3, a decoy receptor for FasL, or for FAP-1, a Fas-associated phosphatase that can block the apoptotic function of Fas. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis did not show consistent differences in the expression of Bcl-2 and Bax between Fas-sensitive and Fas-resistant cell lines examined. These findings indicated that the presence or absence of mRNA expression of DcR3, FAP-1, Bcl-2 and Bax did not always correlate with relative sensitivity to Fas-mediated apoptosis. Treatment of cells with cycloheximide converted the phenotype of resistant cell lines from Fas-resistant to Fas-sensitive, and enhanced the sensitivity of Fas-sensitive cell lines. These results suggest that the Fas-resistance is dependent on the presence of labile proteins that determine resistance to Fas-mediated apoptosis and the apoptotic machinery is already in place in Fas-resistant cell lines.