Tumor-Treating Fields Induce RAW264.7 Macrophage Activation Via NK-?B/MAPK Signaling Pathways

Park, Jeong-In; Song, Kyung-Hee; Jung, Seung-Youn; Ahn, Jiyeon; Hwang, Sang-Gu; Kim, Joon; Kim, Eun Ho; Song, Jie-Young

Nitric oxide (NO) is an important inflammatory mediator that can be produced by activated macrophages to kill tumors and pathogens as well as convey intracellular signals. 15 As shown in Figure 2A , LPS-or TTFs-treated cells increased the messenger RNA (mRNA) and protein expression of iNOS compared with those of the control. The production of NO in TTFs-treated RAW 264.7 cells was slightly increased, whereas LPS stimulation significantly enhanced NO production ( Figure 2B ). It has been demonstrated that activated macrophages exhibit increased ROS accumulation under inflammatory conditions; therefore, we evaluated whether TTFs affect the generation of ROS. As shown in Figure 2C , ROS levels were increased in RAW 264.7 cells when exposed to TTFs for 24 hours. Concomitantly, LPS-induced ROS generation was also evident. These results indicate that TTFs increased the production of NO and ROS in activated RAW 264.7 macrophages.