Novel calcium signaling pathways in cell cycle regulations

在我们两年的合作中，我们广泛讨论了创造各种蛋白激酶的新型和选择性抑制剂的可能性。去年10月在名古屋举行的第71届日本生化学会年会上，L.M.介绍了部分结果。我们共同感兴趣的是异喹啉-磺胺类化合物是否对细胞周期相关激酶的活性具有抑制作用，因为一些异喹啉-磺胺类化合物，如H-7，可以被视为“一般的激酶抑制剂”。因此，我们试图从多种异喹啉化合物中寻找一种cdc2-激酶抑制剂。在调查的几种化合物中，确实发现H-1152及其衍生物在较低浓度下对cdc2激酶有抑制作用。然而，这些抑制剂既不像异嘌呤化合物那样具有选择性，也不像L.M.开发的罗斯科维汀那样具有选择性和效力。这向我们表明，尽管异喹啉和异嘌呤化合物都表现出ATP竞争抑制，但它们的相关抑制机制可能是不同的。另一个有趣的问题是，这些ATP竞争性化合物的抑制效力是否仅仅反映了每个蛋白激酶对ATP的需求，因为这种可能性与异喹啉-磺胺类抑制剂(H-7和HA-1077)对Rho-Kinase的抑制有关。然而，在评估了这些化合物对其他具有不同ATP需求的蛋白激酶的影响后，最终证明了情况并非如此。这是设计新型蛋白激酶抑制剂并将其应用于临床的关键。

During our two-year collaboration, we have extensively discussed the possibility to create novel and selective inhibitors of various protein kinases. A part of the result was presented by L.M.in a symposium of the 7lth Annual meeting of Japanese Biochemical Society held in Nagoya last October. Our mutual interest was whether isoquinoline-sulphonamide derivatives exhibit any inhibition on the activities of cell-cycle-related kinases, because some of the isoquinoline-sulphonamide compounds such as H-7 could be regarded as 'general kinase inhibitors'. Therefore, we attempted to look for a cdc2-kinase inhibitor from a variety of isoquinoline compounds. Among several compounds surveyed, H-1152 and its derivatives were, indeed, found to inhibit cdc2 kinase at low muM concentrations. However, these inhibitors were neither selective nor potent as isopurine compounds as olomoucine or roscovitine developed by L.M.This suggests to us that their relevant mechanisms of inhibition may be distinct, although both isoquinoline and isopurine compounds exhibited ATP-competitive inhibition. Another interest was whether potency of the inhibition by these ATP-competitive compounds may simply reflect a ATP-requirement of each protein kinase, because this possibility was implicated in inhibition of Rho-kinase by isoquinoline-suiphonamide inhibitors (H-7 and HA-1077). Eventually it was proved that such was, however, not the case after evaluation of the effects of these compounds against other protein kinases with different ATP-requirements. This is a crucial point to design novel protein kinase inhibitors and their application to a clinical use.