RESUMO
Cell-death can be necrosis and apoptosis. We are investigating the mechanisms regulating the cell death that occurs on treatment of mouse cancer cell-line FM3A with antitumor 5-fluoro-2'-deoxyuridine (FUdR): necrosis occurs for the original clone F28-7, and apoptosis for its variant F28-7-A. Here we report that a microRNA (miR-351) regulates the cell death pattern. The miR-351 is expressed strongly in F28-7-A but only weakly in F28-7. Induction of a higher expression of miR-351 in F28-7 by transfecting an miRNA mimic into F28-7 resulted in a change of the death mode; necrosis to apoptosis. Furthermore, transfection of an miR-351 inhibitor into F28-7-A resulted in the morphology change, apoptosis to necrosis, in this death-by-FUdR. Possible mechanism involving lamin B1 in this miR-351's regulatory action is discussed.
Assuntos
Apoptose/efeitos dos fármacos , Apoptose/genética , Morte Celular/efeitos dos fármacos , Morte Celular/genética , Desoxiuridina/análogos & derivados , MicroRNAs/genética , MicroRNAs/metabolismo , Animais , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Desoxiuridina/farmacologia , Perfilação da Expressão Gênica , Lamina Tipo B/genética , Lamina Tipo B/metabolismo , Camundongos , MicroRNAs/antagonistas & inibidores , Mimetismo Molecular , Necrose , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transfecção , Regulação para CimaRESUMO
Necrosis and apoptosis are the two major forms of cell death. We have studied the mechanisms that regulate the cell death observed during treatment of mouse cancer cell line FM3A with the anticancer drug 5-fluoro-2'-deoxyuridine (FUdR). To detect causal differences between necrosis and apoptosis, we exploited the necrosis in original clone F28-7 and the apoptosis in its variant F28-7-A that occur on treatment with FUdR. Activating transcription factor 3 (ATF3) was strongly induced during necrosis but not apoptosis. In addition, we found that ATF3 expression is regulated by heat shock protein 90 (HSP90) at the mRNA stage. Knockdown of Atf3 by siRNA in the F28-7 cells resulted in apoptotic morphology rather than necrotic morphology. These results suggest that ATF3 is a cell-death regulator in necrosis and apoptosis.
Assuntos
Fator 3 Ativador da Transcrição/metabolismo , Apoptose , Fator 3 Ativador da Transcrição/genética , Animais , Linhagem Celular Tumoral , Floxuridina/toxicidade , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismo , Camundongos , Necrose , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
Mammalian intracellular ribonuclease L (RNase L) is a latent endoribonuclease that functions against viral infections as an apoptosis-inducing protein, and its activity requires intracellular 5'-end-triphosphorylated-2',5' oligoadenylates (2-5A) as an activator. Previously, we showed that RNase L can be activated in human cancer cell line HT1080 by an RNA polymerase I inhibitor, 1-(3-C-ethynyl-ß-D-ribo-pentofuranosyl)cytosine (3'-ethynylcytidine; ECyd). In ECyd-treated cells, knockdown of the RNase L resulted in a marked decrease in c-jun N-terminal kinase (JNK) phosphorylation, thereby inhibiting apoptosis. We investigate RNase L binding partners by focused proteomic approach using immunoprecipitation with anti-RNase L IgG and mass spectrometry. We found that the IQ motif-containing Ras GTPase-activating-like protein 1 (IQGAP1) can associate with RNase L, and that phosphorylation occurs on the IQGAP1. ECyd-induced JNK phosphorylation and apoptosis were inhibited when IQGAP1 was knocked down with a small interfering RNA. These results raise the interesting possibility that the RNase L-IQGAP1 association may regulate JNK phosphorylation in RNase L-madiated apoptosis. It is likely IQGAP1 works as a regulator in apoptosis.
