Riganti Chiara, Doublier Sophie, Costamagna Costanzo, Aldieri Elisabetta, Pescarmona Gianpiero, Ghigo Dario, Bosia Amalia
Department of Genetics, Biology and Biochemistry, University of Torino, Italy.
Mol Pharmacol. 2008 Aug;74(2):476-84. doi: 10.1124/mol.108.045286. Epub 2008 May 7.
Doxorubicin efficacy in cancer therapy is hampered by the dose-dependent side effects, which may be overcome by reducing the drug's dose and increasing its efficacy. In the present work, we suggest that the activation of the nuclear factor-kappaB (NF-kappaB) pathway and of nitric-oxide (NO) synthase increases the doxorubicin efficacy in human colon cancer HT29 cells. To induce NF-kappaB, we took into account the effect of doxorubicin itself and of the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor simvastatin; as NF-kappaB inhibitors, we chose the sesquiterpene lactones parthenolide and artemisinin. Simvastatin increased the NF-kappaB activity and NO synthesis, elicited the tyrosine nitration of the multidrug resistance-related protein 3, and enhanced the doxorubicin intracellular accumulation and cytotoxicity. Simvastatin potentiated the effect of doxorubicin on the NF-kappaB pathway and the inducible NO synthase expression. The effects of simvastatin were due to the inhibition of the small G-protein RhoA and of its effector Rho kinase. Parthenolide and artemisinin prevented all of the statin effects by inducing RhoA/Rho kinase activation. On the other hand, they did not reduce the NF-kappaB translocation and doxorubicin intracellular content when RhoA was silenced by small interfering RNA (siRNA). It is interesting that RhoA siRNA was sufficient to increase NF-kappaB translocation, NO synthase activity, doxorubicin accumulation, and cytotoxicity also in non-stimulated cells. Our results suggest that artemisinin, a widely used antimalarial drug, may impair the response to doxorubicin in colon cancer cells; on the contrary, simvastatin and RhoA siRNA may represent future therapeutic approaches to improve doxorubicin efficacy, reducing the risk of doxorubicin-dependent adverse effects.
阿霉素在癌症治疗中的疗效受到剂量依赖性副作用的限制，而降低药物剂量并提高其疗效或许可以克服这些副作用。在本研究中，我们认为核因子-κB（NF-κB）信号通路和一氧化氮（NO）合酶的激活可提高阿霉素对人结肠癌HT29细胞的疗效。为诱导NF-κB，我们考虑了阿霉素本身及3-羟基-3-甲基戊二酰辅酶A还原酶抑制剂辛伐他汀的作用；作为NF-κB抑制剂，我们选用了倍半萜内酯小白菊内酯和青蒿素。辛伐他汀增强了NF-κB活性和NO合成，引发了多药耐药相关蛋白3的酪氨酸硝化反应，并增强了阿霉素的细胞内蓄积及细胞毒性。辛伐他汀增强了阿霉素对NF-κB信号通路和诱导型NO合酶表达的作用。辛伐他汀的作用归因于对小G蛋白RhoA及其效应器Rho激酶的抑制。小白菊内酯和青蒿素通过诱导RhoA/Rho激酶激活，阻止了他汀类药物的所有作用。另一方面，当RhoA被小干扰RNA（siRNA）沉默时，它们并未降低NF-κB的易位及阿霉素的细胞内含量。有趣的是，RhoA siRNA在未受刺激的细胞中也足以增加NF-κB易位、NO合酶活性、阿霉素蓄积及细胞毒性。我们的结果表明，广泛使用的抗疟药物青蒿素可能会损害结肠癌细胞对阿霉素的反应；相反，辛伐他汀和RhoA siRNA可能代表未来提高阿霉素疗效、降低阿霉素依赖性不良反应风险的治疗方法。
