Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Department of Bioorganic Chemistry, Sienkiewicza 112, 90-363 Lodz, Poland.
Bioorg Med Chem. 2011 Aug 15;19(16):5053-60. doi: 10.1016/j.bmc.2011.06.028. Epub 2011 Jul 13.
Fragile histidine triad (Fhit) protein encoded by tumour suppressor FHIT gene is a proapoptotic protein with diadenosine polyphosphate (Ap(n)A, n=2-6) hydrolase activity. It has been hypothesised that formation of Fhit-substrate complex results in an apoptosis initiation signal while subsequent hydrolysis of Ap(n)A terminates this action. A series of Ap(n)A analogues have been identified in vitro as strong Fhit ligands [Varnum, J. M.; Baraniak, J.; Kaczmarek, R.; Stec, W. J.; Brenner, C. BMC Chem. Biol.2001, 1, 3]. We assumed that in Fhit-positive cells these compounds might preferentially bind to Fhit and inhibit its hydrolytic activity what would prolong the lifetime of apoptosis initiation signalling complex. Therefore, several Fhit inhibitors were tested for their cytotoxicity and ability to induce apoptosis in Fhit-positive HEK293T cells. These experiments have shown that Ap(4)A analogue, containing a glycerol residue instead of the central pyrophosphate and two terminal phosphorothioates [A(PS)-CH(2)CH(OH)CH(2)-(PS)A (1)], is the most cytotoxic among test compounds (IC(50)=17.5±4.2 μM) and triggers caspase-dependent cell apoptosis. The Fhit-negative HEK293T cells (in which Fhit was silenced by RNAi) were not sensitive to compound 1. These results indicate that the Ap(4)A analogue 1 induces Fhit-dependent apoptosis and therefore, it can be considered as a drug candidate for anticancer therapy in Fhit-positive cancer cells and in Fhit-negative cancer cells, in which re-expression of Fhit was accomplished by gene therapy.
脆性组氨酸三联体（Fhit）蛋白是抑癌基因 FHIT 编码的一种促凋亡蛋白，具有二腺苷多聚磷酸（Ap(n)A，n=2-6）水解酶活性。据推测，Fhit-底物复合物的形成会产生凋亡起始信号，而随后 Ap(n)A 的水解则终止了这一作用。在体外已经鉴定出一系列 Ap(n)A 类似物是强 Fhit 配体[Varnum, J. M.; Baraniak, J.; Kaczmarek, R.; Stec, W. J.; Brenner, C. BMC Chem. Biol.2001, 1, 3]。我们假设在 Fhit 阳性细胞中，这些化合物可能优先与 Fhit 结合并抑制其水解活性，从而延长凋亡起始信号复合物的寿命。因此，我们测试了几种 Fhit 抑制剂对 Fhit 阳性 HEK293T 细胞的细胞毒性和诱导凋亡的能力。这些实验表明，含有甘油残基而非中央焦磷酸和两个末端硫代磷酸酯的 Ap(4)A 类似物[A(PS)-CH(2)CH(OH)CH(2)-(PS)A (1)]在测试化合物中具有最强的细胞毒性（IC(50)=17.5±4.2 μM）并引发 caspase 依赖性细胞凋亡。Fhit 阴性的 HEK293T 细胞（其中 Fhit 被 RNAi 沉默）对化合物 1 不敏感。这些结果表明，Ap(4)A 类似物 1 诱导 Fhit 依赖性凋亡，因此，它可以被认为是 Fhit 阳性癌细胞和 Fhit 阴性癌细胞中抗癌治疗的候选药物，在 Fhit 阴性癌细胞中，可以通过基因治疗实现 Fhit 的重新表达。
