Relationship between long non-coding RNA PCAT-1 expression and gefitinib resistance in non-small-cell lung cancer cells.

Background: Gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has been used as first-line treatment for advanced non-small-cell lung cancer (NSCLC). However, during treatment, cancer cells often develop resistance to gefitinib, the mechanisms of which are not fully understood. This study was designed to elucidate the expression and role of long non-coding RNA (lncRNA)-PCAT-1, a potential biomarker for drug resistance and a therapeutic target for NSCLC, in gefitinib resistance in NSCLC cells.
Methods: In this study, we verified differential PCAT-1 expression in NSCLC gefitinib-resistant tissues or cells. PCAT-1 knockdown, clone formation, Transwell, flow cytometry, and immunofluorescence assays were used to verify the correlation between PCAT-1 and gefitinib sensitivity. A nude mouse tumor-bearing model verified that PCAT-1 can reverse gefitinib resistance in vivo. Then, a PI3K/Akt agonist was used to verify the possible mechanism of PCAT-1 action.
Results: PCAT-1 is highly expressed in gefitinib-resistant NSCLC tissues and cells. PCAT-1 knockdown enhanced gefitinib sensitivity and gefitinib-induced apoptosis in H1299/GR cells. PCAT-1 knockdown reduced tumor volume and weight, and reversed acquired gefitinib resistance in vivo. PCAT-1 knockdown inhibited AKT and GSK3 phosphorylation in H1299/GR cells. A PI3K/AKT agonist reversed PCAT-1 knockdown-mediated enhancement of gefitinib sensitivity in H1299/GR cells CONCLUSION: PCAT-1 knockdown improves sensitivity to gefitinib by inhibition of AKT and GSK3 phosphorylation in NSCLC. PCAT-1 is as potential target for improving the clinical efficacy of gefitinib.