[Inhibitory effect of tumor growth by methionine-enkephalin].
Methionine-enkephalin (Met-Enk) is an endogenous opioid pentapeptide derived from the prohormone proenkephalin A, present in neuroendocrine and hematopoietic cells. Enkephalins are known to play an important role on the processes of induction, activation and control of immunomodulatory events. Met-Enk has been considered a potent antitumoral agent. The present study shows that Met-Enk exerts an inhibitory effect on the growth of a macrophage derived fibrous histiocytoma (MC-II) inoculated intradermally into BALB/cJ mice. Such effect was mainly influenced by the protocol, route of administration and concentration of Met-Enk used for treatment. Neither higher doses of Met-Enk injected intracerebrally or subcutaneously, nor the use of various protocols of treatment, did modify the process of tumorigenesis. In contrast, low dose (0.25 mg/kg) of Met-Enk injected intracerebrally together with tumor inoculation, significantly reduced tumor growth and prolonged survival rate.
Mascarenhas
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Departamento de Patologia, Hospital Universitário Antonio Pedro, Universidade Federal Fluminense (UFF), Niterói RJ, Brasil.
Quirico-Santos
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T
D000704:Analysis of Variance; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D004744:Enkephalin, Methionine / Q000008:administration & dosage / Q000494:pharmacology*; D018219:Histiocytoma, Benign Fibrous / Q000473:pathology*; D007694:Killer Cells, Natural / Q000187:drug effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C
D004744:Enkephalin, Methionine
Efeito inibidor do crescimento tumoral pela metionina-encefalina.