A Novel Peculiarity of TXNIP Reversing the Radioresistance of NPC and Inducing Ferroptosis by xCT-GSH-GPX4-ROS Axis.

Abstract

Radioresistance is a major problem in clinical treatment of nasopharyngeal carcinoma (NPC), and molecular mechanisms of radioresistance related to the antioxidant system are unknown. TXNIP (thioredoxin-interacting protein) is an endogenous inhibitor of thioredoxin. The system xCT/GSH/GPX4 axis is an important antioxidant system of ferroptosis in drug-resistant solid tumor therapy. It is of great clinical significance to study TXNIP and ferroptosis in the role of NPC radioresistance for the therapeutic effect of NPC patients. Immunohistochemistry, qRT-PCR, and WB were used to analyze the expression of TXNIP in clinical samples and NPC cells. Clone formation detected the radioresistance of cells. Flow cytometry, immunofluorescence, and WB were used to analyze intracellular ROS levels and the expression of GPX4 and xCT. Related kits were used to analyze Fe²⁺, MDA, GSH, and mitochondrial membrane potential. A nude mice subcutaneous tumor formation experiment was used for further verification. TXNIP was less expressed in the NPC radioresistant group than in the radiosensitive group. Overexpression of TXNIP promoted apoptosis of NPC cells and showed a dose-dependent response to radiation. In addition, with radiation, TXNIP increased intracellular ROS levels, decreased the expression of GPX4 and xCT, affected the production of intracellular metabolites, such as Fe²⁺, MDA, and GSH, and induced ferroptosis in cells. Stabilized overexpression/knockdown cells significantly affected the growth of tumors in nude mice with radiation. TXNIP is a radiosensitive and ferroptosis-associated gene, which can reverse the radioresistance of NPC by promoting ferroptosis in a dose-dependent manner and through the xCT-GSH-GPX4-ROS axis.