Cold Atmospheric Plasma Suppressed MM In Vivo Engraftment by Increasing ROS and Inhibiting the Notch Signaling Pathway

Multiple myeloma (MM) is the second most common hematologic malignancy. MM stem cells (MMSCs) are thought to be the main causes of in vivo engraftment and eventual recurrence. As a notable new technology, cold atmospheric plasmas (CAPs) show a promising anti-tumor effect, due to their production of various ROS. In this study, we found that different types of plasma could inhibit MM's ability to form cell colonies, suppress MM in vivo engraftment, and extend survival times. We demonstrated that NAC (a ROS scavenger) could block ROS increases and reverse the inhibition of MM's cell-colony-formation ability, which was induced by the plasma treatment. By using a stem cell signaling array, we found that the Notch pathway was inhibited by the plasma treatment; this was further confirmed by conducting real-time PCRs of three MM cell lines. Together, these results constitute the first report of plasma treatment inhibiting MM in vivo engraftment and prolonging survival time by suppressing the Notch pathway via ROS regulation.