Polyi:c Triggers Apoptosis In Human Lung Cancer Cells And Its Related Molecular Mechanisms

ObjectivePolyinosinic-polycytidylic acid (polyi:c) is a synthetic analog of double-stranded RNA. The aim of this study is to reveal the molecular mechanisms of polyi:c's effects of cell proliferation inhibition and apoptosis induction on human lung cancer cells in vitro.MethodsThe effects of intracellular polyi:c delivered by transfection agent on proliferation of lung cancer cell lines A549 and NCI-H446 were assayed by MTT. Annexin V/PI double-stained method was used to evaluate apoptosis of the lung cancer cells A549 and NCI-H446 after polyi:c treatment.The effects of polyi:c on expression of TLR3, MDA-5, RIG-I and IFN-βmRNA were assayed by quantitative real-time PCR. Apoptosis related proteins including Caspase-3, Bcl-2 and Bax, MAPK family protein p-JNK and p-ERK in A549 cells stimulated by intracellular polyi:c were measured by Western Blotting.ResultsThe MTT assay showed intracelluar polyi:c significantly supressed the growth of lung cancer cells A549 and NCI-H446 in a time-and dose-dependent manner. Annexin V/FITC-PI assay revealed that the intracelluar polyi:c treatment markedly induced apoptosis in lung cancer cells A549 and NCI-H446 compared to control group (PBS group, extracelluar polyi:c treatment group and transfection agent). Intracelluar polyi:c stimulation significantly upregulated the expression of TLR3, RLG-I, MDA-5 and IFN-βmRNA, showing significant difference with control groups (p<0.01). The results of Western Blotting demonatrated intracelluar polyi:c activated Caspase-3 and phosphorylation of JNK pathway, but inhibited phosphorylation of ERK pathway in A549 cells.ConclusionsIn our study, intracelluar polyi:c significantly supressed the growth of lung cancer cells and induced apoptosis in lung cancer cells. Intracelluar polyi:c obviously upregulated the expression of TLR3, RIG-I, MDA-5 and IFN-βmRNA. Intracelluar polyi:c induced activation of Caspase-3 and JNK pathway, but suppressed ERK pathway in A549 cells. Polyi:c not only regulates human immune system responses.but also directly triggers apoptosis in the selected lung cancer cells.