RESUMO
Protein synthesis activity is abnormally enhanced in cancer cells to support their uncontrolled growth. However, this process needs to be tightly restricted under metabolic stress-a condition often found within the tumor microenvironment-to preserve cell viability. mTORC1 is critical to link protein synthesis activity to nutrient and oxygen levels, in part by controlling the 4E-BP1-eIF4E axis. Whereas mTORC1 and eIF4E are known pro-tumorigenic factors, whose expression or activity is increased in numerous cancers, the role of 4E-BP1 in cancer is not yet definitive. On the one hand, 4E-BP1 has tumor suppressor activity by inhibiting eIF4E and, thus, blocking mRNA translation and proliferation. This is corroborated by elevated levels of phosphorylated and hence inactive 4E-BP1, which are detected in various cancers. On the other hand, 4E-BP1 has pro-tumorigenic functions as it promotes tumor adaptation to metabolic and genotoxic stress by selectively enhancing or preventing the translation of specific transcripts. Here we describe the molecular and cellular functions of 4E-BP1 and highlight the distinct roles of 4E-BP1 in cancer depending on the microenvironmental context of the tumor.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Fator de Iniciação 4E em Eucariotos/genética , Neoplasias/genética , Fosfoproteínas/genética , Biossíntese de Proteínas , Carcinogênese/genética , Proteínas de Ciclo Celular , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias/patologia , Fosforilação , Ligação Proteica , RNA Mensageiro/genética , Transdução de SinaisRESUMO
The object of this study was the use of naloxone to correct hypoventilation related to the use of morphinomimetics without suppressing the analgesic effect of these agents. The study involved ten patients undergoing gynaecological surgery under neuroleptanalgesia and who at the end of surgery had hypoventilation due to the use of fentanyl (average dose : 4.87 microgram/kg/h) or phenoperidine (average dose : 48.7 microgram/kg/h). Naloxone was administered intravenously in an average dose of 1.37 microgram/kg (in one or two injections) followed by an intramuscular injection of an average of 0.73 microgram/kg. Under these conditions, respiratory depression was completely corrected in all cases, the effect being durable. Good analgesia was retained and there was a normal return to consciousness without undesirable effects.