Knockdown of IGF2BP2 overcomes cisplatin-resistance in lung cancer through downregulating Spon2 gene.

Background: Cisplatin (DDP) resistance has long posed a challenge in the clinical treatment of lung cancer (LC). Insulin-like growth factor 2 binding protein 2 (IGF2BP2) has been identified as an oncogenic factor in LC, whereas its specific role in DDP resistance in LC remains unclear.

Results: In this study, we investigated the role of IGF2BP2 on DDP resistance in DDP-resistant A549 cells (A549/DDP) in vitro and in a DDP-resistant lung tumor-bearing mouse model in vivo. Additionally, methylated RNA immunoprecipitation sequencing (MeRIP-seq) was conducted to identify the potential mRNAs regulated by IGF2BP2, an N6-methyladenosine (m6A) regulator, in the tumor tissues of mice. Compared to normal tissues, IGF2BP2 levels were increased in LC tissues and in relapsed/resistant LC tissues. Most importantly, IGF2BP2 levels were significantly higher in relapsed/resistant LC tissues than in LC tissues. Significantly, knockdown of IGF2BP2 or DDP treatment inhibited A549 cell viability, migration, and cell cycle progression. Consistently, DDP treatment suppressed the viability and migration and triggered cell cycle arrest in A549/DDP cells in vitro, as well as reduced tumor volume and weight of A549/DDP tumor-bearing mice; meanwhile, the combination of DDP and IGF2BP2 siRNA further significantly inhibited A549/DDP cell growth in vitro and in vivo compared to DDP treatment alone. Furthermore, MeRIP-seq data showed that IGF2BP2 downregulation remarkably elevated m6A levels of spondin 2 (Spon2) and reduced mRNA levels of Spon2 in tumor tissues from A549 tumor-bearing mice. Meanwhile, the combination of DDP and IGF2BP2 siRNA notably reduced Spon2 levels, as well as inhibited the viability and induced apoptosis in A549/DDP cells; however, these effects were reversed by Spon2 overexpression.

Conclusion: Collectively, downregulation of IGF2BP2 could overcome DDP resistance in LC through declining the Spon2 gene expression in an m6A-dependent manner. These results may provide a new strategy for overcoming DDP resistance in LC.