The anti-tumor effect of taxifolin on lung cancer via suppressing stemness and epithelial-mesenchymal transition in vitro and oncogenesis in nude mice

Abstract

Taxifolin is a natural flavonoid with anti-oxidant and anti-proliferative properties. In this study, we investigated the stemness-related inhibitory effects of taxifolin in two lung cancer cell lines, A549 and H1975, as well as in A549 xenografts. A549 and H1975 cells, as well as A549 xenograft BALB/c mice were treated with taxifolin. Cell viability, stemness, mobility and protein expression were tested with Cell counting kit-8 (CCK-8), Colony formation assay, Flow cytometry, Transwell, Western blot and Immunohistochemistry, respectively. CCK-8 exhibited an obvious toxicity of taxifolin to both cell lines at higher dose. Then taxifolin of 0, 25, 50, and 100 µM/L were subsequently used. Taxifolin exhibited inhibitory effects on stemness and sphere formation, reduced protein expression of SOX2 and OCT4, and reduced CD133-positive cells. Furthermore, taxifolin decreased invasive cells, reduced N-cadherin and vimentin while increased E-cadherin expression, indicating that epithelial-mesenchymal transition (EMT) was inhibited. All of the effects observed were exhibited in a dose-dependent manner, and A549 cells proved to be more sensitive to taxifolin than H1975 cells. Taxifolin inactivated PI3K and TCF4 protein phosphorylation; however, taxifolin was not observed to have an effect on NF-κB P65 or STAT3. Taxifolin also suppressed tumor growth in A549 xenograft BALB/c mice, with decreased SOX2 and OCT4 expression and inhibited PI3K and TCF4. In summary, taxifolin inhibited stemness and EMT in lung cancer cells possibly via the inactivation of PI3K and OCT4. Taxifolin could be a potential prodrug or serve as an adjuvant in lung cancer treatment.