Combined Anticancer Effect of Treatment with Cold Atmospheric Plasma and Thymidine

Objective: In recent years, the anticancer effect induced by cold atmospheric plasma (CAP) has received much attention and has become a rapidly growing research topic. The purpose of this article is to study the anticancer effect of CAP combined with drugs to seek more efficient anticancer therapy. Methods: The plasma source used in this study was surface air discharge plasma, and the anticancer drug was thymidine (TMD). Breast cancer cells (MCF-7) and cervical cancer cells (HeLa) were treated in vitro to evaluated the anticancer effect of the combination of the two therapy. The anticancer efficiency was assessed by detecting cell viability and cell apoptosis rate. And the combined anticancer mechanism was further analyzed by measuring intracellular reactive oxygen species (ROS) levels. Results: The results of cell viability and cell apoptosis showed that the combined anticancer effect of plasma and TMD was significantly better than TMD treatment alone, but not as good as plasma treatment alone. Intracellular ROS levels were increased by plasma treatment of MCF-7 and HeLa cells, and ROS played an important role in plasma-induced apoptosis of cancer cells. In addition, TMD didn’t induce intracellular ROS production, but only interfered with DNA replication and normal division of cancer cells and could increase the stress of cell division, thus inducing apoptosis of cancer cells. Conclusion: TMD may interfere with the targets of plasma action and affect the anticancer effects of plasma, which indicated that not all anticancer drugs can achieve synergistic effect with plasma, and some drugs even interfere with plasma action.