Nonthermal plasma induces apoptosis in ATC cells: involvement of JNK and p38 MAPK-dependent ROS.

Abstract

PURPOSE: To determine the effects of nonthermal plasma (NTP) induced by helium

(He) alone or He plus oxygen (O(2)) on the generation of reactive oxygen species

(ROS) and cell death in anaplastic thyroid cancer cells. MATERIALS AND METHODS:

NTP was generated in He alone or He plus O(2) blowing through a nozzle by

applying a high alternating current voltage to the discharge electrodes. Optical

emission spectroscopy was used to identify various excited plasma species. The

apoptotic effect of NTP on the anaplastic thyroid cancer cell lines, such as

HTH83, U-HTH 7, and SW1763, was verified with annexin V/propidium staining and

TUNEL assay. ROS formation after NTP treatment was identified with

fluorescence-activated cell sorting with DCFDA staining. The mitogen-activated

protein kinase pathways and caspase cascade were investigated to evaluate the

molecular mechanism involved and cellular targets of plasma. RESULTS: NTP induced

significant apoptosis in all three cancer cell lines. The plasma using He and

O(2) generated more O(2)-related species, and increased apoptosis and

intracellular ROS formation compared with the plasma using He alone. NTP

treatment of SW1763 increased the expression of phosphor-JNK, phosphor-p38, and

caspase-3, but not phosphor-ERK. Apoptosis of SW1763 as well as expressions of

elevated phosphor-JNK, phosphor-p38, and caspase-3 induced by NTP were

effectively inhibited by intracellular ROS scavengers. CONCLUSION: NTP using He

plus O(2) induced significant apoptosis in anaplastic cancer cell lines through

intracellular ROS formation. This may represent a new promising treatment

modality for this highly lethal disease.