Abstract: Objective: To study the influence of chloroquine combined with decitabine in the apoptosis of leukemia K562 cells and KG-1a1Aor1a cells, to explore the effect of autophagy on the leukemia cell apoptosis induced by decitabine, and to clarify its mechanism. Methods: The leukemia K562 and KG-1a1Aor1a cells were cultivated in vitro and divided into blank control group, decitabine group (10 μmol·L^-1) and chloroquine(50 μmol·L^-1) combined with decitabine group (combined group). The leukemia cells in combined group were pre-treated with chloroquine for 6 h before experiment. After treatment with drugs for 24 and 48 h, the number of cells was detected and by CCK-8 method the inhibitory rates of proliferation cells were calculated;the apoptotic rates and mitochondrial membrane potential were detected by flow cytometry. Q-PCR method was carried out to determine the gene expression levels of Atg7 and Atg12, and Western blotting was used to test the protein expression of LC3. Results: After treatment for 24 and 48 h, the number of K562 and KG-1a1Aor1a cells in decitabine group and combined group were decreased compared with blank control group(P<0.05 or P<0.01); the apoptotic rates and mitochondrial membrane potential were remarkably increased (P<0.05 or P<0.01). Compared with decitabine group, the number of K562 and KG-1a1Aor1a in combined group was significantly decreased, and the apoptotic rates were remarkably increased (P<0.05). After treatment for 24 h, the expression levels of Atg7, Atg12 and LC3-Ⅱ/LC3-Ⅰ in the leukemia K562 and KG-1a1Aor1a cells in decitabine group were significantly increased compared with blank control group (P<0.05 or P<0.01);the expression levels of Atg7, Atg12 and LC3-Ⅱ/LC3-Ⅰ in the leukemia K562 and KG-1a1Aor1a cells in combined group were significantly decreased compared with decitabine group (P<0.05 or P<0.01). Conclusion: Decitabine could promote the apoptosis of leukemia cells, and the inhibition of autophagy by chloroquine can promote the apoptosis induced by decitabine.

Key words: decitabine, chloroquine, autophagy, apoptosis