A new selective AKT pharmacological inhibitor reduces resistance to chemotherapeutic drugs, TRAIL, all-trans-retinoic acid, and ionizing radiation of human leukemia cells
A new selective AKT pharmacological inhibitor reduces resistance to chemotherapeutic drugs, TRAIL, all-trans-retinoic acid, and ionizing radiation of human leukemia cells
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DOI：
10.1038/sj.leu.2403044
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发表时间：
2003-09-01
期刊：
影响因子：
11.4
通讯作者：
Cocco, L
中科院分区：
文献类型：
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作者：
Martelli, AM;Tazzari, PL;Cocco, L
现在已经确定，肿瘤细胞通过凋亡进行细胞死亡的能力降低在癌症的发病机制和治疗性治疗失败中起关键作用。事实上，肿瘤细胞经常在信号传导途径上表现出多种改变，导致细胞存活或细胞凋亡。在哺乳动物中，基于磷酸肌醇3-激酶（PI 3 K）/Akt的途径传递极其重要的存活信号，并且其通过PI 3 K的药理学抑制剂的下调显著降低了实体瘤中对各种类型的治疗的抗性。我们最近描述了一个HL 60白血病细胞克隆（HL 60 AR细胞），具有组成型活性PI 3 K/Akt通路。这些细胞对多种化疗药物、全反式维甲酸（ATRA）和肿瘤坏死因子相关凋亡诱导配体（TRAIL）具有耐药性。用两种PI 3 K的药理学抑制剂渥曼青霉素和Ly 294002处理，恢复了HL 60 AR细胞对上述处理的敏感性。然而，这些抑制剂有一些缺点，可能会严重限制或阻碍其临床应用。在这里，我们测试了一种新的选择性Akt抑制剂，1 L-6-羟基-甲基-手性-肌醇2（R）-2-O-甲基-3-O-十八烷基碳酸酯（Akt抑制剂），是否与Ly 294002一样有效地降低HL 60细胞对化疗药物、TRAIL、ATRA和电离辐射的敏感性阈值。我们的研究结果表明，在不影响PI 3 K活性的浓度下，Akt抑制剂显著降低HL 60 AR细胞对依托泊苷、阿糖胞苷、TRAIL、ATRA和电离辐射的抗性。这种作用可能是通过下调抗凋亡蛋白如c-IAP 1、c-IAP 2、cFLIP（L）的表达和Ser 136上的Bad磷酸化来实现的。Akt抑制剂不影响PTEN活性。与Ly 294002不同的是，Akt抑制剂对蛋白激酶C-zeta的磷酸化没有负面影响，并且在下调p70 S6激酶（p70 S6 K）活性方面效果较差。Akt抑制剂增加了K562和U937对凋亡诱导剂的敏感性，但没有增加MOLT-4白血病细胞的敏感性。总体而言，我们的研究结果表明，选择性Akt药理学抑制剂可能在未来用于增强白血病细胞对诱导凋亡的治疗性治疗的敏感性或克服对这些治疗的耐药性。
It is now well established that the reduced capacity of tumor cells of undergoing cell death through apoptosis plays a key role both in the pathogenesis of cancer and in therapeutic treatment failure. Indeed, tumor cells frequently display multiple alterations in signal transduction pathways leading to either cell survival or apoptosis. In mammals, the pathway based on phosphoinositide 3-kinase (PI3K)/Akt conveys survival signals of extreme importance and its downregulation, by means of pharmacological inhibitors of PI3K, considerably lowers resistance to various types of therapy in solid tumors. We recently described an HL60 leukemia cell clone (HL60AR cells) with a constitutively active PI3K/Akt pathway. These cells were resistant to multiple chemotherapeutic drugs, all-trans-retinoic acid ( ATRA), and tumor necrosis factor-related apoptosis-inducing ligand ( TRAIL). Treatment with two pharmacological inhibitors of PI3K, wortmannin and Ly294002, restored sensitivity of HL60AR cells to the aforementioned treatments. However, these inhibitors have some drawbacks that may severely limit or impede their clinical use. Here, we have tested whether or not a new selective Akt inhibitor, 1L-6-hydroxy-methyl-chiro-inositol 2( R)-2-O-methyl-3-O-octadecylcarbonate ( Akt inhibitor), was as effective as Ly294002 in lowering the sensitivity threshold of HL60 cells to chemotherapeutic drugs, TRAIL, ATRA, and ionizing radiation. Our findings demonstrate that, at a concentration which does not affect PI3K activity, the Akt inhibitor markedly reduced resistance of HL60AR cells to etoposide, cytarabine, TRAIL, ATRA, and ionizing radiation. This effect was likely achieved through downregulation of expression of antiapoptotic proteins such as c-IAP1, c-IAP2, cFLIP(L), and of Bad phosphorylation on Ser 136. The Akt inhibitor did not influence PTEN activity. At variance with Ly294002, the Akt inhibitor did not negatively affect phosphorylation of protein kinase C-zeta and it was less effective in downregulating p70S6 kinase (p70S6K) activity. The Akt inhibitor increased sensitivity to apoptotic inducers of K562 and U937, but not of MOLT-4, leukemia cells. Overall, our results indicate that selective Akt pharmacological inhibitors might be used in the future for enhancing the sensitivity of leukemia cells to therapeutic treatments that induce apoptosis or for overcoming resistance to these treatments.