Agbottah Emmanuel, Yeh Wen-I, Berro Reem, Klase Zachary, Pedati Caitlin, Kehn-Hall Kyleen, Wu Weilin, Kashanchi Fatah
Department of Microbiology, George Washington University School of Medicine, Washington, District of Columbia 20037, USA.
AIDS Res Ther. 2008 Jun 10;5:12. doi: 10.1186/1742-6405-5-12.
Human T-cell leukemia virus type-1 (HTLV-1) induces adult T-cell leukemia/lymphoma (ATL/L), a fatal lymphoproliferative disorder, and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a chronic progressive disease of the central nervous system after a long period of latent infection. Although the mechanism of transformation and leukemogenesis is not fully elucidated, there is evidence to suggest that the viral oncoprotein Tax plays a crucial role in these processes through the regulation of several pathways including NF-kappaB and the cell cycle pathways. The observation that NF-kappaB, which is strongly induced by Tax, is indispensable for the maintenance of the malignant phenotype of HTLV-1 by regulating the expression of various genes involved in cell cycle regulation and inhibition of apoptosis provides a possible molecular target for these infected cells. To develop potential new therapeutic strategies for HTLV-1 infected cells, in this present study, we initially screened a battery of NF-kappaB and CDK inhibitors (total of 35 compounds) to examine their effects on the growth and survival of infected T-cell lines. Two drugs namely BMS-345541 and Purvalanol A exhibited higher levels of growth inhibition and apoptosis in infected cell as compared to uninfected cells. BMS-345541 inhibited IKKbeta kinase activity from HTLV-1 infected cells with an IC50 (the 50% of inhibitory concentration) value of 50 nM compared to 500 nM from control cells as measured by in vitro kinase assays. The effects of Purvalanol A were associated with suppression of CDK2/cyclin E complex activity as previously shown by us. Combination of both BMS-345541 and Purvalanol A showed a reduced level of HTLV-1 p19 Gag production in cell culture. The apparent apoptosis in these infected cells were associated with increased caspase-3 activity and PARP cleavage. The potent and selective apoptotic effects of these drugs suggest that both BMS-345541 and Purvalanol A, which target both NF-kappaB and CDK complex and the G1/S border, might be promising new agents in the treatment of these infected patients.
人类嗜T细胞病毒1型（HTLV-1）可诱发成人T细胞白血病/淋巴瘤（ATL/L），这是一种致命的淋巴细胞增殖性疾病，以及HTLV-1相关脊髓病/热带痉挛性截瘫（HAM/TSP），这是一种在长期潜伏感染后发生的中枢神经系统慢性进行性疾病。尽管转化和白血病发生的机制尚未完全阐明，但有证据表明病毒癌蛋白Tax通过调节包括NF-κB和细胞周期途径在内的多种途径在这些过程中发挥关键作用。Tax强烈诱导的NF-κB通过调节参与细胞周期调控和抑制细胞凋亡的各种基因的表达，对于维持HTLV-1的恶性表型不可或缺，这一观察结果为这些受感染细胞提供了一个可能的分子靶点。为了开发针对HTLV-1感染细胞的潜在新治疗策略，在本研究中，我们首先筛选了一系列NF-κB和CDK抑制剂（共35种化合物），以研究它们对受感染T细胞系生长和存活的影响。与未感染细胞相比，两种药物BMS-345541和Purvalanol A在感染细胞中表现出更高水平的生长抑制和细胞凋亡。通过体外激酶测定，BMS-345541抑制HTLV-1感染细胞中IKKβ激酶活性的IC50（抑制浓度的50%）值为50 nM，而对照细胞为500 nM。如我们之前所示，Purvalanol A的作用与抑制CDK2/细胞周期蛋白E复合物活性有关。BMS-345541和Purvalanol A联合使用在细胞培养中显示出HTLV-1 p19 Gag产生水平降低。这些感染细胞中明显的细胞凋亡与caspase-3活性增加和PARP裂解有关。这些药物强大而选择性的凋亡作用表明，靶向NF-κB和CDK复合物以及G1/S边界的BMS-345541和Purvalanol A可能是治疗这些感染患者的有前景的新药物。
