Study on effects of total saponins from Lilii Bulbus on proliferation, apoptosis, invasion and metastasis of lung cancer cells and its preliminary mechanism

Abstract

The potential role of total saponins extracted from Lilium lancifolium bulbs (TSLL) on the proliferation, apoptosis, migration and invasion of human lung cancer A549 cells and its possible mechanism were discussed. Effect of TSLL on proliferation of A549 cells were detected by CCK-8, clone formation assay and EdU staining. Effect of TSLL on apoptosis morphology of A549 cells was observed by fluorescence microscope using Annexin V/PI double staining and Hoechst 33342 staining. Effect of TSLL on cell migration and invasion was detected by Transwell migration test and Transwell invasion test, respectively. Western blot was used to detect TSLL on the expression change of intracellular associated proteins. Results showed that TSLL intervention in A549 cells within 24, 48 or 72 h significantly inhibited cell growth, and its IC₅₀values were about 229, 173 and 71 mg·L⁻¹, respectively. TSLL significantly reduced the clone formation rate of A549 cells and decreased the DNA synthesis rate of A549 cells in a concentration dependent manner. TSLL induced A549 cells apoptosis and reduced the migratory behavior of A549 cells. TSLL decreased invasion of A549 cells to the artificial basement membrane. The expression level of intracellular PCNA and the ratio of Bcl-2/Bax protein were down-regulated and procaspase 3 was activated. In addition, TSLL had no obvious effect on epithelial mesenchymal transition (EMT) related marker proteins E-cadherin and vimentin expression. The above results indicated that TSLL possess inhibitory effects against proliferation, migration and invasion of lung cancer A549 cells and apoptosis-induced effect. The anti-proliferation effect of TSLL is very likely by inhibiting intracellular DNA synthesis through reducing the expression of PCNA in lung cancer cells. And the apoptosis induction of TSLL on lung cancer cells is associated with the regulation of Bcl-2 and Bax proteins expression. Nevertheless, there is no incontestable correlation between anti-invasion and metastasis effects of TSLL and EMT in lung cancer cells.