OBJECTIVETo explore the effect of Wnt signaling suppression on proliferation of non small cell lung cancer to gefitinib, and its related mechanisms.

METHODSPC9 and PC9/AB2 cells of both gefitinib sensitive and resistant were treated with different concentrations of gefitinib, and the proliferation index was measured using CCK8 kit. The members of Wnt signaling pathway were detected by Western blot. Dual luciferase reportor gene assay (TOP Flash) was used to document the transcriptional level of β-catenin. β-catenin siRNA was transfected into PC9/AB2 cells to suppress the Wnt signaling transcription, followed by treatment with different concentrations of gefitinib. Western blot was then used to detect the expression of EGFR and its downstream signaling after inhibit the expression of β-catenin.

RESULTSTreating with different concentrations of gefitinib, the resistance of PC9/AB2 cells to gefitinib was significantly increased (P < 0.05). The members of Wnt signaling expressed at higher level in PC9/AB2 cells than in PC9 cells (t = 24.590, P = 0.000). TOP Flash examination showed that the endogenous transcriptional activity of Wnt signaling was higher in PC9/AB2 cell than that in PC9 cell (t = 4.983, P = 0.008). Compared with the negative control group, apoptotic rate and sensitivity to gefitinib significantly increased in interfered group (P < 0.05). The expression of p-ERK1/2 significantly decreased after Wnt signaling suppression, although other proteins showed no significant alterations.

CONCLUSIONSuppressing the activity of Wnt signaling can partly reverse the celluar resistance to gefitinib in non small cell lung cancer.