Inhibition of cell proliferation by mild hyperthermia at 43˚C with Paris Saponin I in the lung adenocarcinoma cell line PC-9.

Rhizoma paridis is widely used for cancer therapy due to its potential involvement in the suppression of tumor growth. However, at present there is no clear explanation for the mechanism underlying the inhibitory effects of Rhizoma paridis combined with hyperthermia on tumor growth. The aim of the present study was to evaluate the effects of Paris saponin I (PSI) combined with hyperthermia on a variety of non-small cell lung cancer (NSCLC) cell lines. An MTT assay was used to determine the levels of growth inhibition. The cell cycle was analyzed using flow cytometry and cell apoptosis was analyzed with Annexin V/propidium iodide staining and the Hoechst assay. The morphology of cells during apoptosis was determined using a transmission electron microscope. The expression levels of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax) and caspase-3 proteins were detected using western blotting. The inhibition rates significantly increased with PSI in combination with hyperthermia at 43˚C. PSI with hyperthermia at 43˚C caused G2/M phase arrest and significantly induced apoptosis. The expression level of Bcl-2 decreased, while Bax expression increased following treatment with PSI with hyperthermia at 43˚C. In addition, the protein expression of caspase-3 was significantly enhanced. PSI combined with hyperthermia is a potent antitumor treatment through the inhibition of proliferation of NSCLC cells and may be developed as a new antitumor therapy. PSI combined with hyperthermia significantly induced apoptosis through a multi regulatory process involving G2/M arrest and regulation of Bax, Bcl-2 and caspase-3 expression, resulting in cell death and tumor inhibition.