Inhibition of lung cancer cell growth by quercetin glucuronides via G2/M arrest and induction of apoptosis. Drug Metab. Dispos

Lung cancer is the leading cause of cancer death in many devel-oped countries, including Taiwan. Quercetin, a widely distributed bioflavonoid, is well known to induce growth inhibition in a variety of human cancer cells. Quercetin glucuronides are the main circu-lating metabolites after dietary supplements with quercetin in hu-mans. However, there is little information available as to how quercetin glucuronides affect human cancer cells. We investigated the effects of quercetin glucuronides in a human lung cancer cell line NCI-H209. We checked the cell viability, cell cycle checkpoint proteins, pro- and antiapoptotic proteins, caspase-3 activity, and gene expression by flow cytometry and Western blot. The viability of cells decreased in a dose- and time-dependent manner. Cell cycle analysis revealed a significant increase of the proportion of cells in G2/M phase and subG0/G1 phase (corresponding to apo-ptotic cells). Moreover, quercetin glucuronides increased the ex