Radiosensitizing effects of Cyclocarya paliurus polysaccharide on hypoxic A549 and H520 human non-small cell lung carcinoma cells

Cyclocarya paliurus (CP) polysaccharide (CPP) is a chemical component contained in CP, which has been reported to possess significant hypoglycemic activity. The present study aimed to investigate the radiosensitizing effect and underlying mechanisms of CPP on hypoxic A549 and H520 human non-small cell lung carcinoma cells. Cell viability, apoptosis and proliferation were determined using Cell Counting kit-8 assay, flow cytometry and colony formation assay, respectively. mRNA and protein expression levels were determined by reverse transcription-quantitative PCR and western blot analysis, respectively. The results suggested that CPP markedly inhibited the viability of hypoxic A549 and H520 cells. In response to combined treatment with CPP and radiation, hypoxic A549 and H520 cells exhibited enhanced apoptosis; in addition, cell proliferation was suppressed and the expression levels of hypoxia-inducible factor-1α, survivin and cleaved caspase-3 were modified. Furthermore, CPP in combination with radiation affected the mammalian target of rapamycin (mTOR)/Akt/phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway. These findings indicated that CPP may enhance the radiosensitivity of hypoxic A549 and H520 cells; this effect may be associated with inhibition of the mTOR/Akt/PI3K pathway. The potential radiosensitizing effects of CPP on hypoxic A549 and H520 cells suggested that CPP may be an effective target for treatment of non-small cell lung carcinoma.