RESUMO
BACKGROUND AND OBJECTIVES: Interferon alpha2a (IFNalpha2a) mediates important antiviral, antiproliferative and immunomodulatory responses and is employed in the treatment of human diseases, including chronic myelogenous leukemia. Here, we report the IFNalpha2a-dependent expression profiles of three malignant cell lines derived from liver, lymphocytes and muscle. DESIGN AND METHODS: The experiments were performed in the presence of cycloheximide, thus our results exclusively reflect direct transcriptional modulation. The short exposure time i.e. 5 hours evidences only the early events, excluding the effects of complex phenotypic changes on the expression. RESULTS: Our findings indicate that IFNalpha2a rapidly up-regulates the expression of STAT1, STAT2 and ISGF3G genes. This activity should result in the amplification of the cellular response to the cytokine. Moreover, IFNalpha2a directly modulates the expression of: (i) important transcriptional factors, e.g. IRF1 and IRF7 which control pivotal cellular events, and (ii) enzymes involved in the IFNalpha2a-dependent antiviral and apoptotic response. Interestingly, we showed that the cytokine induces transcriptional expression of Sjögren's syndrome antigen A1, a protein involved in several autoimmune diseases. INTERPRETATION AND CONCLUSIONS: The observed changes induced by IFNalpha2a could be related to the development of autoimmune syndromes observed during IFNalpha2a treatment. A number of genes transcriptionally regulated by the cytokine have been identified for the first time; these might represent additional effectors of IFNalpha2a activity.
Assuntos
Citocinas/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Interferon-alfa/farmacologia , Proteínas de Neoplasias/genética , Transcrição Gênica/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/biossíntese , Proteínas Reguladoras de Apoptose/genética , Sequência de Bases , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral/efeitos dos fármacos , Linhagem Celular Tumoral/metabolismo , Cicloeximida/farmacologia , Citocinas/biossíntese , Humanos , Interferon alfa-2 , Fator Gênico 3 Estimulado por Interferon, Subunidade gama/biossíntese , Fator Gênico 3 Estimulado por Interferon, Subunidade gama/genética , Células K562/efeitos dos fármacos , Células K562/metabolismo , Neoplasias Hepáticas/patologia , Proteínas de Membrana Transportadoras/biossíntese , Proteínas de Membrana Transportadoras/genética , Dados de Sequência Molecular , Proteínas da Mielina/biossíntese , Proteínas da Mielina/genética , Proteínas Proteolipídicas Associadas a Linfócitos e Mielina , Proteínas de Neoplasias/biossíntese , Análise de Sequência com Séries de Oligonucleotídeos , Regiões Promotoras Genéticas , Inibidores da Síntese de Proteínas/farmacologia , Proteolipídeos/biossíntese , Proteolipídeos/genética , Proteínas Recombinantes , Rabdomiossarcoma/patologia , Ribonucleoproteínas/biossíntese , Ribonucleoproteínas/genética , Fator de Transcrição STAT1/biossíntese , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT2/biossíntese , Fator de Transcrição STAT2/genéticaRESUMO
An altered apoptotic response represents a pivotal feature of cancer and is involved in cancerogenesis and resistance to chemotherapy. So far, however, only a few studies have been devoted to survey caspase content in malignant cell lines and primary tumor specimens. In this report, we investigated the expression of two pivotal caspases, 3 and 8, in 63 neuroblastoma specimens by three complementary techniques (i.e., reverse transcriptase polymerase chain reaction, immunoblotting, and immunohistochemistry). We confirmed the frequent absence of caspase 8 expression. Moreover and most important, we demonstrated, for the first time to our knowledge, that a significant percentage of neuroblastomas lack caspase 3 mRNA and protein. Both caspase alterations do not show any correlation with tumor stage and MYCN status. Immunohistochemistry showed a large number of caspase-negative cell islets also present in positive samples. Our findings suggest that the absence of caspases might play an important role in neuroblastoma development and resistance to apoptosis-based treatments.
