FOXO3a regulation of non-small cell lung cancer radiotherapy resistance through the PINK1/Parkin pathway of protective mitophagy.

Abstract

Background: Radiotherapy resistance has become one of the major causes of radiotherapy failure among patients with non-small cell lung cancer (NSCLC), but its underlying mechanism remains unclear. In recent years, the influence of mitochondrial autophagy on the radiotherapy resistance in treated tumor cells and its regulatory mechanism has become a hotspot in research, which is also the subject of our group research effort. The primary objective of our study is to investigate the mitophagy-associated pathway and the regulatory mechanisms underlying radiotherapy resistance in NSCLC.

Methods: We developed biologically stable radiotherapy-resistant NSCLC cell models A549/X and H520/X and verified the radioresistance of these cells. Subsequently, through high-throughput transcriptomic sequencing analysis and experimental verification, we found that the Forkhead box O 3a (FOXO3a) gene and the PINK1/Parkin mitochondrial autophagy pathway in NSCLC radiotherapy-resistant cell lines were consistent and upregulated more reactively than those of parent cells. The effect of gene expression status of the FOXO3a-PINK1/Parkin pathway on the survival outcomes of NSCLC was analyzed in The Cancer Genome Atlas (TCGA) database. Next, we inoculated nude mouse xenografts with small interfering RNA to interfere with the FOXO3a gene and short hairpin RNA to construct radiotherapy-resistant stable strains of NSCLC with stable knockdown of FOXO3a gene. Subsequently, the association and regulation of FOXO3a gene expression levels with radioresistance and mitochondrial autophagy PINK1/Parkin pathway at the cellular and animal levels were determined.

Results: The expression level of FOXO3a gene in NSCLC radioresistant cells was significantly positively correlated with the level of mitophagy and the expression level of PINK1/Parkin pathway. Higher expression levels of genes in the FOXO3a-PINK1/Parkin pathway had a negative effect on survival outcomes in NSCLC and were positively correlated with the radioresistance of cells.

Conclusions: FOXO3a regulates NSCLC radioresistance by modulating the mitochondrial autophagy PINK1/Parkin pathway, which may serve as a new molecular intervention target and therapeutic entry point for intervening and improving the radioresistance of patients with NSCLC in clinical practice.