Diosmetin induces apoptosis and enhances the chemotherapeutic efficacy of paclitaxel in non-small cell lung cancer cells via Nrf2 inhibition.

Background And Purpose: Non-small-cell lung cancer (NSCLC) accounts for up to 80-85% of all lung cancers and has a disappointing prognosis. Flavonoids exert anticancer properties, mostly involving stimulation of ROS production without significant toxicity to normal cells. This study was aimed to delineate the effect of diosmetin, a natural flavonoid, on NSCLC cells and its ability to enhance the antitumour activity of paclitaxel.

Experimental Approach: NSCLC cells, normal cell lines HLF-1 and BEAS-2B, and immunodeficient mice were chosen as models to study the effects of diosmetin. Changes in cell viability, apoptosis, and ROS were analysed by MTT assay, flow cytometry assay, and fluorescent probe DCFH-DA. Expression of proteins and mRNA was determined by Western blotting and real-time RT-PCR. Growth of xenografted tumours was measured. Spleens and other vital organs were analysed with histological and immunohistochemical techniques.

Key Results: Diosmetin induced selective apoptotic death in NSCLC cells but spared normal cells, via ROS accumulation. Diosmetin induced ROS production in NSCLC cells probably via reducing Nrf2 stability through disruption of the PI3K/Akt/GSK-3β pathway. The in vitro and in vivo xenograft studies showed that combined treatment of diosmetin and paclitaxel synergistically suppressed NSCLC cells. Histological analysis of vital organs showed no obvious toxicity of diosmetin, which matched our in vitro findings.

Conclusions And Implications: Diosmetin selectively induced apoptosis and enhanced the efficacy of paclitaxel in NSCLC cells via ROS accumulation through disruption of the PI3K/Akt/GSK-3β/Nrf2 pathway. Therefore, diosmetin may be a promising candidate for adjuvant treatment of NSCLC.