Molecular Mechanism Of Quinoline Derivative CQ-24 Inhibiting Colorectal Cancer Cells Proliferation

As one of the common gastrointestinal malignant tumors,colorectal cancer has become one of the diseases that seriously threaten human health due to its increasing morbidity and mortality.At present,the main treatment for colorectal cancer include surgery,chemotherapy,radiotherapy,targeted therapy and so on.Existing clinical drugs for colorectal cancer are very limited,and are often accompanied by shortcomings such as high toxic and side effects,poor targeting,and drug resistance.Therefore,it is of great significance to find out novel anti-colorectal cancer drugs as soon as possible.In recent years,Quinoline derivatives have been proven to have significant application in the development of anticancer drugs.A variety of new synthetic methods have been discovered,using quinoline as a substrate to synthesize new derivatives,and these derivatives all exhibit good antitumor activity.We used compound CQ-24,a new quinoline derivatice,as a candidate drug for colorectal cancer and conducted a preliminary study on the molecular mechanism of its inhibition of colorectal cancer cell proliferation.The aim of this study is to investigate the effect of CQ-24 on colorectal cancer cell activity in vitro and its mechanism.The experimental results showed that CQ-24 was significantly toxic to human colorectal cancer cell lines and inhibit the growth activity and clonal formation rate of cells in vitro.Apoptosis and autophagy are two common mechanisms of programmed cell death.Annexin-ⅤFITC/PI assay revealed no significant change in apoptosis rate.Western blot analysis showed no significant change in the expression levels of several proteins related to apoptosis after drug stimulation.Moreover,the cytotoxicity of CQ-24 in HCT116 p53^-/-or bax^-/-cells did not change.The above experimental results indicated that CQ-24 does not inhibit the growth of tumor cells by inducing apoptosis.The cell cycle was not changed after CQ-24 treatment,either.On the other hand,it is found that CQ-24 can induce autophagy.When HCT116 were stimulated by 3μM CQ-24 for 2 hours,we observed some autophagosomes and autolysosomes under the electron microscope.When cells were stimulated for 4 hours,we observed the fluorescence spot aggregation of m Cherry-EGFP-LC3B.Werstern blot experiment further showed that the expression levels of autophagy marker proteins LC3 and p62 changed significantly after the stimulation.The above experimental results demonstrated that CQ-24 could induce autophagy flow in HCT116.When we treated the HCT116 ATG5^-/-cells and ATG7^-/-cells with CQ-24,we found that these knockout cells were less sensitive to CQ-24 compared with wide-type cells,thus we inferred that ATG5 and ATG7 are key factors for CQ-24 to induce autophagy.In summary,our study found that compound CQ-24 can inhibit the growth of colorectal cancer cells by inducing autophagy in vitro and its molecular mechanism involves the participation of autophagy-related proteins ATG5 and ATG7.CQ-24,as a novel quinoline derivative,has a promising application prospects in the treatment of colorectal cancer.