Chaetoglobosin A Induces T-24 Apoptosis in Human Bladder Cancer Cells Through Oxidative Stress and MAPK/PI3K-AKT-mTOR Pathway

Chaetoglobosin A (ChA) is an antitumor compound produced by Chaetomium globosum. However, the mechanism of its antitumor effect has been rarely reported. In this study, we evaluated the anti-proliferative effect of ChA on human bladder cancer T-24 cells and explored its mechanism of action. ChA was found to have a good inhibitory effect on T-24 cells by MTT assay with an IC 50 value of 48.14 ± 10.25 µΜ. Moreover, it was found to have a migration inhibitory ability and a sustained proliferation inhibitory effect on tumor cells by cell aggregation assay and cell migration assay. The appearance of apoptotic morphology was observed by Hoechst 33342 staining after ChA (25, 50, 75 µΜ) treatment, while Annexin V-FITC/PI double-staining assay also demonstrated that the number of apoptotic cells increased with the increase of drug concentration. Flow cytometry results showed that ChA treatment increased reactive oxygen species (ROS) and decreased mitochondrial membrane potential (MMP) in T-24 cells and inhibited cell mitosis, resulting in an increase in the number of sub-G1 phase cells. Further Western Blot experiments demonstrated that MAPK and PI3K-AKT-mTOR pathways were activated after drug treatment in addition to endogenous and exogenous apoptotic pathways. The addition of the ROS inhibitor N-acetylcysteine (NAC) upregulated the expression level of Bcl-2 protein, decreased p38 phosphorylation, increased ERK phosphorylation and restored the levels of PI3K and p-mTOR after ChA treatment. These suggest that regulation of oxidative stress, MAPK and PI3K-AKT-mTOR signaling pathways affect apoptosis.