Vichalkovski Anton, Kotevic Ivana, Gebhardt Niculina, Kaderli Reto, Porzig Hartmut
Institute of Pharmacology, University of Bern, Friedbuehlstrasse 49, CH-3010 Bern, Switzerland.
Cell Calcium. 2006 Jun;39(6):517-28. doi: 10.1016/j.ceca.2006.03.001. Epub 2006 Apr 18.
We have used a recombinant mouse pre-B cell line (TonB210.1, expressing Bcr/Abl under the control of an inducible promoter) and several human leukemia cell lines to study the effect of high tyrosine kinase activity on G protein-coupled receptor (GPCR) agonist-stimulated cellular Ca(2+) release and store-operated Ca(2+) entry (SOCE). After induction of Bcr/Abl expression, GPCR-linked SOCE increased. The effect was reverted in the presence of the specific Abl inhibitor imatinib (1microM) and the Src inhibitor PP2 (10microM). In leukemic cell lines constitutively expressing high tyrosine kinase activity, Ca(2+) transients were reduced by imatinib and/or PP2. Ca(2+) transients were enhanced by specific inhibitors of PKC subtypes and this effect was amplified by tyrosine kinase inhibition in Bcr/Abl expressing TonB210.1 and K562 cells. Under all conditions Ca(2+) transients were essentially blocked by the PKC activator PMA. In Bcr/Abl expressing (but not in native) TonB210.1 cells, tyrosine kinase inhibitors enhanced PKCalpha catalytic activity and PKCalpha co-immunoprecipitated with Bcr/Abl. Unlike native TonB210.1 cells, Bcr/Abl expressing cells showed a high rate of cell death if Ca(2+) influx was reduced by complexing extracellular Ca(2+) with BAPTA. Our data suggest that tonic inhibition of PKC represents a mechanism by which high tyrosine kinase activity can enhance cellular Ca(2+) transients and thus exert profound effects on the proliferation, apoptosis and chemotaxis of leukemic cells.
我们使用了一种重组小鼠前B细胞系（TonB210.1，在可诱导启动子的控制下表达Bcr/Abl）和几种人类白血病细胞系，以研究高酪氨酸激酶活性对G蛋白偶联受体（GPCR）激动剂刺激的细胞Ca(2+)释放和储存操纵性Ca(2+)内流（SOCE）的影响。在诱导Bcr/Abl表达后，GPCR相关的SOCE增加。在存在特异性Abl抑制剂伊马替尼（1μM）和Src抑制剂PP2（10μM）的情况下，这种效应被逆转。在组成性表达高酪氨酸激酶活性的白血病细胞系中，伊马替尼和/或PP2可降低Ca(2+)瞬变。PKC亚型的特异性抑制剂可增强Ca(2+)瞬变，并且在表达Bcr/Abl的TonB210.1和K562细胞中，酪氨酸激酶抑制可放大这种效应。在所有条件下，PKC激活剂PMA基本上可阻断Ca(2+)瞬变。在表达Bcr/Abl（而非天然）的TonB210.1细胞中，酪氨酸激酶抑制剂可增强PKCα催化活性，并且PKCα与Bcr/Abl共免疫沉淀。与天然TonB210.1细胞不同，如果通过用BAPTA络合细胞外Ca(2+)来减少Ca(2+)内流，表达Bcr/Abl的细胞会显示出高细胞死亡率。我们的数据表明，PKC的紧张性抑制代表了一种机制，通过该机制高酪氨酸激酶活性可增强细胞Ca(2+)瞬变，从而对白血病细胞的增殖、凋亡和趋化性产生深远影响。
