Apigenin promotes cell death in NCI-H23 cells by upregulation of PTEN: potential involvement of the binding of apigenin with WWP2 protein.

The tumour suppressor protein PTEN is often down-regulated in non-small cell lung cancer. A major protein promoting the lowering of the PTEN protein is WWP2. Polyphenols have been shown to promote the expression of tumour suppressor genes like PTEN. We carry out the study to check for the ability of apigenin to bind with the WWP2 protein using in-silico investigation comprising docking and simulation. We checked for the cytotoxic effect of apigenin upon the non-small cell lung cancer cell line NCI-H23. We checked the PTEN expression status at the gene and protein levels. The expression levels of the apoptotic regulators BCL2, BAX and CASPASE3 genes along with the activity levels of the caspase-3 protein were checked. The ultrastructure of the cells was analysed. Our Autodock analysis showed that apigenin bound favourably with the WWP2 protein. Molecular dynamics simulation revealed that apigenin increased the parameters of RMSD, Rg and SASA when bound with the WWP2 protein. The protein-ligand complex had hydrogen bonding and majorly van der Wal's interactions. PCA analysis revealed greater fluctuations in the apigenin-bound state of the protein. The mutant form of the WWP2 revealed similar results in the presence of apigenin. Apigenin showed efficacy against the NCI-H23 cell line and promoted PTEN protein levels, lowered BCL2 gene expression and up-regulated BAX and CASPASE3 gene expression. Increased caspase-3 activity and ultra-structural analysis revealed the occurrence of apoptosis. Thus the binding of apigenin with WWP2 could promote PTEN protein levels and lead to apoptotic activity in NCI-H23 cells.Communicated by Ramaswamy H. Sarma.