Silencing of APEX1 triggers ferroptosis in clear cell renal cell carcinoma via APP-mediated activation of p53/xCT signaling

Background

Apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) is involved in regulating the proliferation, invasion, migration, and other malignant progression of various cancer cells. However, its mechanism in clear cell renal cell carcinoma (ccRCC) remains unclear.

Methods

UALCAN database was performed to predict APEX1 expression in ccRCC. CCK-8, colony formation, EdU, wound healing, transwell, and flow cytometry assays were used to assess cell proliferation, migration, invasion, and cell cycle. Expressions of cell cycle proteins and ferroptosis biomarkers were detected by Western blot. The levels of Fe²⁺, ROS, MDA, SOD, and GSH in cells were detected by assay kits. Fluorescent probe was used to monitor the intracellular lipid peroxidation level. The binding of APEX1 and amyloid precursor protein (APP) was validated by Co-IP. The expressions of p53/xCT pathway proteins were examined by Western blot.

Results

The results showed that APEX1 was highly expressed in ccRCC tissues and positively correlated with poor prognosis. Silencing of APEX1 inhibited the proliferation, invasion, and migration of Caki-1 cells and induced cell cycle arrest. This silencing also led to increased levels of intracellular Fe²⁺, lipid peroxidation, and ROS, thereby inducing cell ferroptosis. APEX1 could bind to APP, and their expressions were negatively correlated. Silencing of APP reversed the inhibition effects of APEX1 silencing on proliferation, invasion, migration, and cell cycle in Caki-1 cells. Moreover, silencing of APEX1 up-regulated the p53/xCT signaling by binding to APP, thereby promoting ferroptosis.

Conclusion

In summary, silencing of APEX1 promotes ferroptosis and inhibits the malignant progression of ccRCC, potentially through APP-mediated activation of p53/AKT signaling, providing a novel therapeutic strategy for ccRCC treatment.