Methionine enkephalin suppresses metabolic activity of a leukemic cell line (NALM-1) and enhances CD10 expression.
NALM-1 cells (a cell line derived from human pre-B leukemia) were exposed to the opioid pentapeptide methionine-enkephalin (Met-enkephalin) and/or to thiorphan, an inhibitor of the enzyme that degrades the enkephalins (membrane endopeptidase EC 3.4.24.11, CALLA, the CD10 marker). Metabolic and proliferative activity was assessed after 6, 24 and 48 h in microplates using a colorimetric assay with vital dye MTT. CD10 expression was determined by means of semi-quantitative RT-PCR. Exposure to the Met-enkephalin at concentrations of 10(-8)-10(-6) M for 6 h reduced the MTT-activity, and after 24 and 48 h the suppression waned. Thiorphan (5 x 10(-6) M) abrogated the suppressive effect of the enkephalin, and after 6 h converted suppression into stimulation. Met-enkephalin (10(-6) M) increased and thiorphan (2.5 x 10(-6)-10(-6) M) decreased expression of CD10 at the RNA level. Suppression of the MTT uptake was attributed to the products of Met-enkephalin degradation caused by the enzymatic activity of CD10.
Martin-Kleiner
Irena
I
Division of Molecular Medicine, Ruder Bosković Institute, PO Box 180, 10002 Zagreb, Croatia. kleiner@rudjer.irb.hr
Gabrilovac
Jelka
J
Kusec
Rajko
R
Boranić
Milivoj
M
D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D006801:Humans; D007938:Leukemia / Q000378:metabolism*; D015260:Neprilysin / Q000096:biosynthesis*; D011480:Protease Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013778:Tetrazolium Salts; D013844:Thiazoles; D015244:Thiorphan / Q000494:pharmacology
D018076:DNA, Complementary; D011480:Protease Inhibitors; D012333:RNA, Messenger; D013778:Tetrazolium Salts; D013844:Thiazoles; D004744:Enkephalin, Methionine; D015244:Thiorphan; D015260:Neprilysin; C022616:thiazolyl blue