IMP2 drives chemoresistance by repressing cisplatin-induced apoptosis and ferroptosis via activation of IPO4 and SLC7A11 under hypoxia in bladder cancer.

Abstract

Background: Cisplatin resistance is the leading cause of mortality in muscle-invasive bladder cancer (MIBC) cases. Previous evidence suggests that abnormal epitranscriptome modifications are associated with reduced chemotherapy responses. However, the exact underlying mechanism remains largely unknown.

Methods: Insulin-like growth factor-2 mRNA-binding protein 2 (IMP2) was identified by clustered regularly interspaced short palindromic repeats (CRISPR) data screening, single-cell RNA-sequencing and sample analysis. To evaluate the regulatory role of IMP2, functional studies were conducted both in vitro and in vivo. To elucidate the underlying mechanisms, various techniques including immunofluorescence, fluorescent in situ hybridization, RNA pull-down, coimmunoprecipitation, and RNA immunoprecipitation were used.

Results: Our study revealed that IMP2 was overexpressed in chemoresistant MIBC and lung metastasis tissues. IMP2 inhibition markedly enhanced the sensitivity of BC cells to cisplatin both in vitro and in vivo. Mechanistically, IMP2 enhanced the mRNA stability of IPO4 and SLC7A11 in a m6A-dependent manner, augmenting the nuclear translocation of C/EBPδ to activate PRKDC-mediated DNA damage repair in response to cisplatin. Moreover, IMP2 upregulated SLC7A11 levels and suppressed cisplatin-induced ferroptosis. Combining ferroptosis and apoptosis inhibitors completely reversed cisplatin resistance caused by IMP2 overexpression. LINC00941, which was induced by HIF-1α-mediated transcriptional activation, specifically bound IMP2 and protects it from degradation.

Conclusions: This work demonstrated a novel mechanism involving the IMP2-IPO4/SLC7A11 pathway as a promising treatment target for cisplatin-resistant bladder cancer.