lncRNA UCA1 Promotes Gefitinib Resistance as a ceRNA to Target FOSL2 by Sponging miR-143 in Non-small Cell Lung Cancer

Exosomes could mediate cell-cell crosstalk in cancer progression by transferring long noncoding RNAs (lncRNAs). The aim of this study is to explore the roles of the exosomal lncRNA urothelial carcinoma-associated 1 (UCA1) on gefitinib resistance in non-small cell lung cancer (NSCLC). First, we detected the expression of UCA1 in gefitinib-resistant and gefitinib-sensitive NSCLC by quantitative real-time PCR; the expression occurred in tissues, cell lines, and exosomes. Cell phenotypes and animal experiments were performed to determine the effects of UCA1 and exosomal UCA1. Furthermore, bioinformatics online programs and luciferase reporter assay were used to validate the association of UCA1 and miR-143 in NSCLC cells. We observed that UCA1 was increased in both gefitinib-resistant NSCLC cells and their secreted exosomes. In vitro and in vivo experiments demonstrated that UCA1 knockdown impaired cell proliferation and promoted the gefitinib-induced cell apoptosis. Then we demonstrated that repressed UCA1 promoted the miR-143 expression, and miR-143 could bind to the predicted binding site of UCA1. We then dissected the effect of miR-143 on gefitinib resistance in NSCLC and proved the suppressive role of miR-143. Furthermore, we found that miR-143 displayed its role via modulating the FOSL2 expression. In summary, our findings indicate that exosomal UCA1 may serve as a promising therapeutic target for the treatment of epidermal growth factor receptor-positive (EGER(+)) NSCLC patients.