The kinesin light chain‐2, a target of mRNA stabilizing protein HuR, inhibits p53 protein phosphorylation to promote radioresistance in NSCLC

Abstract

Background: Radioresistance hinders radiotherapy for the treatment of lung cancer. Kinesin light chain-2 (KLC2) has been found to be upregulated in lung cancer and also to be associated with poor prognosis. This study aimed to investigate the effect of KLC2 on radiosensitivity in lung cancer. Methods: The radioresistant role of KLC2 was determined by colony formation, neutral comet assay, and γH2AX immunofluorescent staining assay. We further verified the function of KLC2 in a xenograft tumor model. The downstream of KLC2 was identified through gene set enrichment analysis and validated by western blot. Finally, we analyzed clinical data from the TCGA database to reveal the upstream transcription factor of KLC2, which was validated by RNA binding protein immunoprecipitation assay.Results: Here, we found that downregulation of KLC2 could significantly reduce colony formation, increase γH2AX level, and double-stranded DNA breaks in vitro. Meanwhile, overexpressed KLC2 significantly increased the proportion of the S phase in lung cancer cells. KLC2 knockdown could activate P53 pathway, and ultimately promoting radiosensitivity. The mRNA of KLC2 was observed to bind with Huantigen R (HuR). The mRNA and protein expression of KLC2 in lung cancer cells was significantly reduced when combined with siRNA-HuR. Interestingly, KLC2 overexpression significantly increased the expression of HuR in lung cancer cells. Conclusion: Taken together, these results indicated that HuR-KLC2 forms a positive feedback loop, which decreases the phosphorylation of p53 and thereby weaken the radiosensitivity of lung cancer cells. Our findings highlight the potential prognosis and therapeutic target value of KLC2 in lung cancer patients treated with radiotherapy.

Tackling the HuRdle of radioresistance: a radiation perspective on the RNA-binding protein HuR

“…Most studies found an increased level of DNA double strand breaks in HuR low-expressing cells ( 12 , 13 , 16 ). This finding was associated with increased caspase activation ( 12 , 16 , 18 ), decreased kinesin light chain-2 ( 21 ) and Snail ( 16 ), and decreased expression of the genomic stability marker AT-rich interactive domain-containing protein 1A (ARID1A) ( 21 ) and WEE1 ( 22 ) as well as the repair markers ataxia-telangiectasia mutated (ATM), Ku80, and RAD51 ( 19 ). HuR has also been associated with cancer stem cells ( 23 ) which have been linked to a specific gene expression profile and are known to be highly radioresistant ( 24 ).…”