Experimental study on the inhibitory effects of chloroquine combined with radiotherapy on NSCLC cells

Objective To investigate the inhibitory effects of chloroquine(CQ) combined with radiation therapy on the proliferation and metastasis of non-small cell lung cancer(NSCLC) cells, and its main mechanism.

Methods A549 and PC-9 cells were cultured in vitro, and divided into the control group, CQ(8 μmol/L) single administration treatment group, IR(4 Gy/8 Gy) single radiotherapy treatment group and CQ(8 μmol/L)+IR (4 Gy/8 Gy) combined treatment group. The CQ was pretreated for 1 h, and radiotherapy treatment was performed. The colony cloning assay and EdU incorporation assay were used to detect the proliferation of cells, the Transwell assay was used to detect the invasive and migratory ability of cells, the flow cytometry was used to detect the apoptosis rate of cells, the electron microscopy was used to observe the autophagy level of cells, and the Western blotting was used to detect the expression of autophagy and apoptosis-related proteins of cells in each experimental group.

Results The results of colony cloning assay and EdU incorporation assay showed that the CQ combined with radiotherapy significantly inhibited the proliferation of A549 and PC-9 cells compared with the CQ or radiotherapy alone treatment group(P < 0.01). The results of Transwell assay showed that the CQ combined with radiotherapy significantly inhibited the invasion and migration of A549 and PC-9 cells(P < 0.01). The results of flow cytometry showed that the CQ combined with radiotherapy increased the apoptosis of A549 and PC-9 cells(P < 0.05). The results of electron microscopy showed that the CQ could inhibit radiotherapy-induced autophagy(P < 0.01). The results of Western blotting showed that the Caspase 3 levels were up-regulated, while Bcl-2 levels were decreased in the CQ combined with radiotherapy group, and the increasing of protein expression levels of LC3Ⅱ and p62 were significantly more than those in the single drug or single radiotherapy treatment group(P < 0.01).

Conclusions CQ inhibits radiotherapy-induced autophagy, and CQ combined with radiotherapy inhibits the proliferation, invasion and migration, and promotes the apoptosis of NSCLC cells.