Inhibition of primary ciliogenesis enhances efficacy of EGFR‑TKIs against non‑small cell lung cancer cells.

Primary cilia are antenna‑like organelles on almost all human cells that sense and transduce extracellular cues into cellular response. Primary cilia have been reported to be implicated in drug resistance in several cancer types, but their roles in cellular response to epidermal growth factor receptor (EGFR)‑tyrosine kinase inhibitors (TKIs) in non‑small cell lung cancer (NSCLC) are still not fully understood. In the present study, it was reported that primary cilia are more prevalent in EGFR‑TKI‑insensitive A549 and H23 cells compared with the drug‑sensitive HCC827 and PC9 cells by immunofluorescence staining assay. Importantly, treatment with EGFR‑TKIs (gefitinib and dacomitinib) results in a dose‑dependent increase in cilia number and length in A549 and H23 cells, an effect not observed in HCC827 and PC9 cells. Upon administration of gefitinib, A549 cells predominantly arrest in the G1 phase detected by flow cytometric analysis, with a minority undergoing cell death and the majority entering senescence. Inhibition of ciliogenesis through the knockdown of IFT88 or ARL13B by targeted small interfering RNAs markedly enhances the sensitivity of A549 cells to EGFR‑TKIs by promoting a shift from senescence to cell death. Furthermore, it was demonstrated by immunoblotting and immunofluorescence colocalization analysis that both the expression and ciliary localization of adenylate cyclase 3 (AC3) are significantly upregulated following EGFR‑TKIs treatment, and the reduction of AC3 expression effectively mitigates cellular drug resistance in A549 cells. These findings highlight a critical role for the cilia‑AC3 axis in modulating cellular response to EGFR‑TKIs, suggesting it as a potential therapeutic target for the treatment of NSCLC.