Apoptotic effect of PP2 a Src tyrosine kinase inhibitor, in murine B cell leukemia.
Src is a non-receptor protein tyrosine kinase that transduces signals regulating cell growth and differentiation. We report here that activation of signaling pathway after blockade of tyrosine phosphorylation by PP2 (4-amino-5-(4-chloro-phenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine), a potent and selective inhibitor of the Src-family tyrosine kinase, can lead to cell death in murine B cell leukemia, 70Z/3. Death from PP2 occurred by apoptosis as indicated by the induction of caspase activation and annexin V/propidium iodide staining. Interestingly, PP2 was found to be able to enhance the DNA binding activity of nuclear factor kappaB (NF-kappaB) before induction of apoptosis without accompanying by increased phosphorylation of inhibitor of NF-kappaB-alpha (IkappaB-alpha). Additionally, immunoblotting analysis with PP2-treated cell extract demonstrated that, compared to other protein kinase C (PKC) isotypes, the translocation of novel PKC isotypes from the cytosol to membrane fraction was sustained for a longer time. These data suggest that the inhibition of Src-mediated tyrosine phosphorylation by PP2 may tilt the balance between each PKC isotypes, which in turn, activate NF-kappaB transcription factor, leading to apoptosis.
Lee
Michael
M
Korea Institute of Toxicology, Korea Research Institute of Chemical Technology, P.O. Box 123, Yusong, Daejeon 305-600, Republic of Korea. mikelee@kitox.re.kr
Kim
Ji-Young
JY
Koh
Woo Suk
WS
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D007527:Isoenzymes / Q000378:metabolism; D015448:Leukemia, B-Cell / Q000188:drug therapy / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014407:Tumor Cells, Cultured; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000097782:NF-kappaB-Inducing Kinase
D020169:Caspases; D007527:Isoenzymes; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011743:Pyrimidines; D019061:src-Family Kinases; D000097782:NF-kappaB-Inducing Kinase; C412373:AG 1879