Drugs in tumor suppressor gene p53-activated apoptosis of human non-small cell lung cancer cells
| Autor: | Wang, Jing-Ping, 王景平 |
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| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 Part I In this study, we demonstrated that the growth of human non-small cell lung cancer (NSCLC) cells H460 and A549 cells can be inhibited by low concentrations of an epoxide derivative, teroxirone, in both in vitro and in vivo models. The cytotoxicity was mediated by apoptotic cell death through DNA damage. The onset of ultimate apoptosis is dependent on the status of p53. Teroxirone caused transient elevation of p53 that activates downstream p21 and procaspase-3 cleavage. The presence of caspase-3 inhibitor reverted apoptotic phenotype. Furthermore, we showed the cytotoxicity of teroxirone in H1299 cells with stable ectopic expression of p53, but not those of mutant p53. A siRNA-mediated knockdown of p53 expression attenuated drug sensitivity. The in vivo experiments demonstrated that teroxirone suppressed growth of xenograft tumors in nude mice. Being a potential therapeutic agent by restraining cell growth through apoptotic death at low concentrations, teroxirone provides a feasible perspective in reversing tumorigenic phenotype of human lung cancer cells. The results indicated that low concentrations of teroxirone suppressed the growth of human non-small cell lung cancer cells. The induced apoptotic cell death can be reverted by caspase-3 inhibitor, DEVD-CHO. The reduced cell viability is closely related to p53-activated apoptosis. Furthermore, we also found that teroxirone-induced p53-dependent apoptosis was through regulating intrinsic pathway via ROS generation and mitochondria dysfunction, which can reverted by antioxidant NAC. Teroxirone provides a good candidate for lung cancer treatment by suppressing cellular proliferation. Part II Topoisomerase II inhibitor ellipticine effectively suppressed the growth of human non-small cell lung cancer (NSCLC) epithelial cells. Previously, we reported the drug activity was consummated through parallel nucleus migration of p53 and Akt in A549 cells. While inducing cell death, the drug activity was proved related to autophagy through phosphorylated Akt at S473. In addition, ellipticine induced cytotoxicity in p53-null H1299 cells with stable expression of ectopic p53. In this work, we further demonstrated that dominant-negative AktS473A or p53 shRNA inhibited ellipticine-mediated translocalization of p53 and Akt and attenuated apoptotic cell death in A549 cells. The presence of p53 predates ellipticine-mediated apoptotic cell death, assists in nucleus translocation of phosphorylated Akt and activation of autophagy pathway. Growth inhibition through collaborating p53 and phosphorylated Akt473 in lung epithelial cancer cells provided a new perspective of the topoisomerase inhibitor as an effective cancer therapy agent. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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