Plumbagin from Plumbago Zeylanica L Induces Apoptosis in Human Non-small Cell Lung Cancer Cell Lines through NF-κB Inactivation

Objective: To detect effects of plumbagin on proliferation and apoptosis in non-small cell lung cancer cell lines, and investigate the underlying mechanisms. Materials and Methods: Human non-small cell lung cancer cell lines A549, H292 and H460 were treated with various concentrations of plumbagin. Cell proliferation rates was determined using both cell counting kit-8 (CCK-8) and clonogenic assays. Apoptosis was detected by annexin V/propidium iodide double-labeled flow cytometry and TUNEL assay. The levels of reactive oxygen species (ROS) were detected by flow cytometry. Activity of NF-${\kappa}B$ was examined by electrophoretic mobility shift assay (EMSA) and luciferase reporter assay. Western blotting was used to assess the expression of both NF-${\kappa}B$ regulated apoptotic-related gene and activation of p65 and $I{\kappa}B{\kappa}$. Results: Plumbagin dose-dependently inhibited proliferation of the lung cancer cells. The IC50 values of plumbagin in A549, H292, and H460 cells were 10.3 ${\mu}mol/L$, 7.3 ${\mu}mol/L$, and 6.1 ${\mu}mol/L$ for 12 hours, respectively. The compound concentration-dependently induced apoptosis of the three cell lines. Treatment with plumbagin increased the intracellular level of ROS, and inhibited the activation of NK-${\kappa}B$. In addition to inhibition of NF-${\kappa}B$/p65 nuclear translocation, the compound also suppressed the degradation of $I{\kappa}B{\kappa}$. ROS scavenger NAC highly reversed the effect of plumbagin on apoptosis and inactivation of NK-${\kappa}B$ in H460 cell line. Treatment with plumbagin also increased the activity of caspase-9 and caspase-3, downregulated the expression of Bcl-2, upregulated the expression of Bax, Bak, and CytC. Conclusions: Plumbagin inhibits cell growth and induces apoptosis in human lung cancer cells through an NF-${\kappa}B$-regulated mitochondrial-mediated pathway, involving activation of ROS.