Daidzein-rich isoflavones aglycone inhibits lung cancer growth through inhibition of NF-κB signaling pathway.

To develop anti-tumor agents for lung cancer, we aim to characterize a herbal compound, daidzein-rich isoflavones aglycone (DRIA), in inhibiting the proliferation and NF-κB signaling pathway of lung cancer. MTT and colony formation assays were used to analyze the proliferation of lung cancer cells in presence of DRIA treatment, which showed that DRIA dose-dependently inhibited the proliferation and colony formation of lung cancer cells. Enzyme-linked immunosorbent assay revealed that interleukin-6 (IL6) and interleukin-8 (IL-8) levels were reduced by DRIA. p65-NFκB expression and activation, which was enhanced by TNF-α and C/EBPβ treatment, were attenuated by DRIA. Exogenous tumor necrosis factor-α (TNF-α) and CCAAT/enhancer binding protein (C/EBPβ) were used to enhance NF-κB signaling in cells, and the effects of DRIA in attenuating NF-κB signaling were assessed by analyzing p65-NFκB expression in mRNA and protein levels, using quantitative real-time PCR (qRT-PCR), western blot and immunofluorescence staining. immunohistochemical staining revealed that Ki-67 and p65-NF-κB levels in A594 tumor xenografts of A594 tumors were also reduced by DRIA treatment in mice. Our data indicates that DRIA is effective in inhibiting the proliferation and NFκB signaling of lung cancer both in vitro and in vivo.