RESUMO
Human erythrocytes release neokyotorphin, the 137-141 fragment of hemoglobin alpha-chain into the supernatant of red blood cells primary culture. However, the neokyotorphin fragment 1-4 that is formed together with neokyotorphin inside the red blood cells and in various tissues is not found in the supernatant. Both neokyotorphin and its 1-4 fragment were shown to stimulate proliferation of L929 tumor cells.
Assuntos
Divisão Celular/efeitos dos fármacos , Endorfinas/metabolismo , Eritrócitos/metabolismo , Fragmentos de Peptídeos/metabolismo , Cromatografia Líquida de Alta Pressão , Endorfinas/farmacologia , Humanos , Fragmentos de Peptídeos/farmacologia , Análise de Sequência , Células Tumorais CultivadasRESUMO
Valorphin, an endogenous opioid-like hemoglobin fragment, is cytotoxic for L929 and K562 tumor cells in 10(-7)-10(-13) M concentration range. Because cytolytic effects induced by valorphin in K562 cells are inhibited by naloxone, opioid receptors should be involved in induction of valorphin-mediated tumor cell death. Three distinct cytolytic processes, differing in the onset time and the development time, take place with K562 cells within 10-18 h of incubation with valorphin. All three processes are not associated with apoptotic mechanism of cell death.
Assuntos
Adamantano/análogos & derivados , Morte Celular/efeitos dos fármacos , Adamantano/antagonistas & inibidores , Adamantano/farmacologia , Analgésicos Opioides/farmacologia , Animais , Apoptose , Dano ao DNA/efeitos dos fármacos , Eletroforese em Gel de Ágar , Encefalina Metionina/farmacologia , Hemoglobinas/química , Humanos , Camundongos , Naloxona/farmacologia , Receptores Opioides/metabolismo , Células Tumorais CultivadasRESUMO
Acetylcholine receptor ligands were studied for cytotoxicity in K562 human erythroid leukemia tumor cells. Cytotoxicity of carbachol, an agonist of acetylcholine receptors, atropine, an antagonist of muscarinic acetylcholine receptor, neurotoxin 11 (NT II) from Naja naja oxiana cobra venom and tubocurarine, antagonists of acetylcholine receptor of nicotinic type was exhibited in the 10-7-10-5 M concentration range. Several cytolytic processes, two for carbachol and three for other ligands, corresponding to different concentrations of each ligand were detected. All acetylcholine receptor ligands induced internucleosomal DNA fragmentation.
RESUMO
OBJECTIVE: Cytolytic activity of TNF was analysed at L929 and K562 tumor cell lines. METHODS: TNF-mediated cytotoxicity was studied within 10(-6)-10(-17) M concentration range after 18 h of incubation with target cells. RESULTS: TNF caused reliable cytotoxicity values in both cell lines, while L929 cells were more sensitive to cytolytic action of the protein than K562 cells. Three cytotoxicity maxima were detected at each cell line: at concentrations of 10(-6) M, 10(-17) M and 10(-15) M in K562 cells and at concentrations of 10(-7) M, 10(-11) M, 10(-14), 10(-16) M in L929 cells. CONCLUSIONS: DNA fragmentation analysis demonstrated that all cytolytic processes induced by TNF in L929 cells are associated with apoptotic mechanism of cell death, while cytolytic process induced in K562 cells differed in DNA fragmentation patterns: cytolytic processes induced by 10(-6) M of TNF was of apoptotic type, while the other processes were not associated with internucleosomal DNA cleavage.
Assuntos
Citotoxicidade Imunológica/efeitos dos fármacos , Fragmentação do DNA/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular , Humanos , Camundongos , Células Tumorais Cultivadas , Fator de Necrose Tumoral alfa/administração & dosagemRESUMO
The content of biologically active hemoglobin fragment neokyotorphin (TSKYR) as well as that of neokyotorphin fragment (1-4) (TSKY) were determined in extracts of lung, heart, and brain tissue of rats. The content of both peptides as well as the neokyotorphin/neokyotorphin(1-4) ratio differed significantly from each other in these tissues. The respective parameters deviate considerably from those of erythocytes where these peptides are originally formed. Comparative analysis of cytolytic activity of peptides was performed at human erythroid leukaemia (K562) and murine transformed fibroblast (L929) cell lines. TSKY showed reliable cytolytic activity in both cell lines, while neokytorphin was not cytotoxic. The data obtained lead to speculation that endogenous hemoglobin fragments might participate in regulation of tumor growth in vivo.
Assuntos
Endorfinas/metabolismo , Fragmentos de Peptídeos/metabolismo , Sequência de Aminoácidos , Animais , Encéfalo/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Endorfinas/farmacologia , Humanos , Leucemia Eritroblástica Aguda/patologia , Pulmão/metabolismo , Camundongos , Dados de Sequência Molecular , Miocárdio/metabolismo , Fragmentos de Peptídeos/farmacologia , Ratos , Células Tumorais CultivadasRESUMO
Cytolytic activity of Met-enkephalin, an endogenous opioid peptide, was studied within the 10(-7)-10(-17) M concentration range in K562 human erythroid leukemia cells. Cytolytic activity was determined by the trypan blue inclusion method after 13, 15 and 18 h of Met-enkephalin co-incubation with target cells. Discrete maxima of cytolytic activity were detected at concentrations of 10(-9)-10(-10), 10(-13) and 10(-15) M. Cytolysis was accompanied by internucleosomal DNA fragmentation which is indicative of the mechanism of cell death being apoptosis.
