Comparison of ability of protein kinase C inhibitors to arrest cell growth and to alter cellular protein kinase C localisation.
Comparison of ability of protein kinase C inhibitors to arrest cell growth and to alter cellular protein kinase C localisation.
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DOI：
10.1038/bjc.1995.137
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发表时间：
1995-04
影响因子：
8.8
通讯作者：
Gescher, A
中科院分区：
文献类型：
--
作者：
Courage, C;Budworth, J;Gescher, A
蛋白激酶C的抑制剂如星形孢子素类似物UCN-01和CGP 41251具有抗肿瘤作用，但其细胞抑制作用的机制尚不清楚。我们测试了一种假设，即这些化合物阻止生长的能力与它们抑制PKC的倾向内在地联系在一起。在A549和MCF-7癌细胞中研究了具有不同程度的PKC活性和特异性的化合物。将抑制细胞生长50%的药物浓度(IC50)的对数值与抑制胞浆PKC活性的IC50值的对数作图，可以区分两组化合物。含有较强的酶活性抑制物(钙磷蛋白C、星形孢子素及其类似物UcN-01、RO31-8220、CGp 41251)的组生长抑制作用较强，而较弱的酶抑制物(三甲基鞘氨醇、米替福辛、鼻咽癌-15437、H-7、H-7I)对增殖的影响较小。GF109203X是个例外，它对PKC有抑制作用，IC50在10(-8)M范围内，但仅有微弱的细胞抑制作用。为了证实PKC在这些药物引起的生长抑制中的作用，用1微米的Bryostatin 1孵育细胞，以耗尽PKC。研究了这些缺乏酶的细胞对星形孢菌素、RO31-8220、UCN-01或H-7诱导的生长停滞的敏感性。抑制[~3H]胸腺嘧啶核苷掺入去PKC的A549细胞50%的药物浓度略低于对照细胞，但不显著低于对照组。这些结果表明，PKC不太可能在这些药物介导的A549和MCF-7细胞生长抑制中发挥直接作用。星状孢子素不仅是一种强的PKC抑制剂，而且还模拟该酶的激活剂，因为它能引起某些PKC同工酶的细胞重新分布。研究了不同于星形孢菌素的激酶抑制剂发挥类似作用的能力。Calphostin C、H-7、H-7I、米替福辛、星形孢子素、Ucn-01、RO31-8220、CGp 41251或GF 109203X与A549细胞在没有或存在蛋白激酶C激活剂12-O-十四酰佛波醇-13-醋酸酯的情况下孵育30min。用Western印迹法检测PKC-α、-epsilon和-Zeta的亚细胞分布。没有一种药物影响PKC-α或-Zeta。
Inhibitors of protein kinase C (PKC) such as the staurosporine analogues UCN-01 and CGP 41251 possess antineoplastic properties, but the mechanism of their cytostatic action is not understood. We tested the hypothesis that the ability of these compounds to arrest growth is intrinsically linked with their propensity to inhibit PKC. Compounds with varying degrees of potency and specificity for PKC were investigated in A549 and MCF-7 carcinoma cells. When the log values of drug concentration which arrested cell growth by 50% (IC50) were plotted against the logs of the IC50 values for inhibition of cytosolic PKC activity, two groups of compound could be distinguished. The group which comprised the more potent inhibitors of enzyme activity (calphostin C, staurosporine and its analogues UCN-01, RO 31-8220, CGP 41251) were the stronger growth inhibitors, whereas the weaker enzyme inhibitors (trimethylsphingosine, miltefosine, NPC-15437, H-7, H-7I) affected proliferation less potently. GF 109203X was exceptional in that it inhibited PKC with an IC50 in the 10(-8) M range, yet was only weakly cytostatic. To substantiate the role of PKC in the growth inhibition caused by these agents, cells were depleted of PKC by incubation with bryostatin 1 (1 microM). The susceptibility of these enzyme-depleted cells towards growth arrest induced by staurosporine, RO 31-8220, UCN-01 or H-7 was studied. The drug concentrations which inhibited incorporation of [3H]thymidine into PKC-depleted A549 cells by 50% were slightly, but not significantly, lower than significantly, lower than those observed in control cells. These results suggest that PKC is unlikely to play a direct role in the arrest of the growth of A549 and MCF-7 cells mediated by these agents. Staurosporine is not only a strong inhibitor of PKC but also mimics activators of this enzyme in that it elicits the cellular redistribution of certain PKC isoenzymes. The ability of kinase inhibitors other than staurosporine to exert a similar effect was investigated. Calphostin C, H-7, H-7I, miltefosine, staurosporine, UCN-01, RO 31-8220, CGP 41251 or GF 109203X were incubated for 30 min with A549 cells in the absence or presence of the PKC activator 12-O-tetradecanoyl phorbol-13-acetate. The subcellular distribution of PKC-alpha-, -epsilon and -zeta was measured by Western blot analysis. None of the agents affected PKC-alpha or -zeta.(ABSTRACT TRUNCATED AT 400 WORDS)