Hydroxychloroquine facilitates autophagosome formation but not degradation to suppress the proliferation of cervical cancer SiHa cells

Hydroxychloroquine (HCQ), the hydroxylated analog of chloroquine, is an antimalarial lysomotropic agent that inhibits autophagy due to lysosomal acidification, and subsequently blocks the fusion of autophagosomes with lysosomes which leads to the accumulation of autophagosomes that may accelerate tumor cell death. Given these hypothesis the aim of this study was to investigate the effects of HCQ in the inhibition of autophagy and the induction of apoptosis in cervical cancer SiHa cells. Cervical cancer SiHa cells were cultured with Hank's balanced salt solution (HBSS) as positive control of autophagy or treated with HCQ as part of the experimental groups. LC3 and P62/SQSTM1 were detected by quantitative polymerase chain reaction (qPCR) and western blotting, respectively in order to evaluate initially autophagosome formation and their degradation. Specific green fluorescent protein (GFP)-LC3 was subsequently detected by fluorescence microscopy in order to confirm the formation of autophagosomes. MTT and flow cytometry were adopted respectively to assess the proliferation and apoptosis of the SiHa cells. miRNA-9* was also investigated. The results demonstrated that HCQ increased the expressions of LC3 mRNA and LC3Ⅱ protein and GFP-LC3 signalling but reduced the expression of p62/STSQM1 in cervical cancer SiHa cells. These results indicated HCQ has the ability to inhibit autophagy as incapable of degrading the autophagosome. However, HCQ may promote SiHa cell apoptosis as the MTT, apoptotic assay and miRNA-9* results revealed. HCQ has the ability to inhibit autophagy by blocking the degradation of autophagosomes and subsequently facilitates the apoptosis of cervical cancer SiHa cells.