lncRNA IGFL2-AS1 mediates NSCLC chemoresistance via YBX1-induced HSPA1A/RAP1 activation

BACKGROUND: The development of drug resistance in cancer is associated with multiple malignant properties, including proliferative progression, metastasis, and stemness. Long noncoding RNAs (lncRNAs) reportedly contribute to multidrug resistance in lung cancer. However, functional and mechanistic studies of key lncRNAs associated with lung cancer are lacking.

METHODS: Candidate lncRNA IGFL2-AS1 and its downstream target, the HSPA1A and RAP1 cascade, were identified using RNA sequencing. In vitro functional assays, including proliferation, clonal formation, Transwell migration, sphere formation, and drug sensitivity test, were conducted to explore the function of the IGFL2-AS1/HSPA1A axis in lung cancer. For in vivo functional validation, subcutaneous implantation and tail vein injection of luciferase-tagged lung cancer cells were performed in mouse models. Moreover, RNA pulldown, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP), and point/truncated mutations were utilized to dissect the mechanisms underlying the activation of the YBX1-mediated IGFL2-AS1/HSPA1A axis. Pharmacological inhibition of HSPA1A was performed to restore chemotherapy sensitivity and attenuate lung cancer cell metastasis in vivo. Finally, tissue microarray staining was employed to evaluate the expression of the YBX1/IGFL2-AS1/HSPA1A/RAP1 axis in lung cancer specimens and its correlation with prognosis.

RESULTS: IGFL2-AS1, stimulated by C/EBPβ, was aberrantly upregulated in chemoresistant cell lines and lung cancer specimens. IGFL2-AS1 promoted lung cancer proliferation, metastasis, drug resistance, and stemness by upregulating HSPA1A expression both in vitro and in vivo. Mechanistically, IGFL2-AS1 recruited YBX1 to the HSPA1A promoter, facilitating its transcription. Pharmacological inhibition of HSPA1A restored the sensitization of A549 cells resistant to cisplatin and 5-fluorouracil via the downstream RAP1 signaling cascade. Notably, the YBX1/IGFL2-AS1/HSPA1A axis was consistently activated in lung cancer specimens and correlated with poor patient prognosis.

CONCLUSIONS: This study demonstrated that the YBX1-modulated IGFL2-AS1/HSPA1A/RAP1 axis is aberrantly activated in lung cancer cells and is associated with unfavorable prognosis, highlighting its potential as a novel therapeutic target in clinical settings.