Aravindan Natarajan, Shanmugasundaram Karthigayan, Natarajan Mohan
Department of Radiation Oncology, OUPB 1430, University of Oklahoma Health Sciences Center, 825 N. E. 10th Street, Oklahoma City, OK 73104, USA.
Mol Cell Biochem. 2009 Jul;327(1-2):29-37. doi: 10.1007/s11010-009-0039-z. Epub 2009 Feb 15.
Conceptual approaches of heat-induced cytotoxic effects against tumor cells must address factors affecting therapeutic index, i.e., the relative toxicity for neoplastic versus normal tissues. Accordingly, we investigated the effect of hyperthermia treatment (HT) on the induction of DNA fragmentation, apoptosis, cell-cycle distribution, NFkappaB mRNA expression, DNA-binding activity, and phosphorylation of IkappaBalpha in the normal human Mono Mac 6 (MM6) cells. For HT, cells were exposed to 43 degrees C. FACS analysis showed a 48.5% increase in apoptosis, increased S-phase fraction, and reduced G2 phase fraction after 43 degrees C treatments. EMSA analysis showed a dose-dependent inhibition of NFkappaB DNA-binding activity after HT. This HT-mediated inhibition of NFkappaB was persistent even after 48 h. Immunoblotting analysis revealed dose-dependent inhibition of IkappaBalpha phosphorylation. Similarly, RPA analysis showed that HT persistently inhibits NFkappaB mRNA. These results demonstrate that apoptosis upon HT exposure of MM6 cells is regulated by IkappaBalpha phosphorylation mediated suppression of NFkappaB.
热诱导对肿瘤细胞产生细胞毒性作用的概念性方法必须考虑影响治疗指数的因素，即肿瘤组织与正常组织的相对毒性。因此，我们研究了热疗（HT）对正常人单核巨噬细胞6（MM6）细胞中DNA片段化、凋亡、细胞周期分布、NFκB mRNA表达、DNA结合活性以及IκBα磷酸化的影响。对于热疗，细胞暴露于43℃。流式细胞术分析显示，在43℃处理后，凋亡增加48.5%，S期比例增加，G2期比例降低。电泳迁移率变动分析（EMSA）显示热疗后NFκB DNA结合活性呈剂量依赖性抑制。即使在48小时后，这种热疗介导的NFκB抑制作用仍然持续。免疫印迹分析显示IκBα磷酸化呈剂量依赖性抑制。同样，核糖核酸酶保护分析（RPA）表明热疗持续抑制NFκB mRNA。这些结果表明，MM6细胞热疗后凋亡是由IκBα磷酸化介导的NFκB抑制所调节的。
