Taraxastane inhibits the proliferation, migration and invasion of human cervical cancer by inducing ROS- mediated necrosis like cell death, cell cycle arrest and modulation of JNK/MAPK signaling pathway

Purpose: A good number of anticancer studies have focused on the evaluation of plant derived natural products against different types of human cancers. Triterpenes, belonging to terpenoid class of plant secondary metabolites, have been reported to function as potent anticancer agents. The current study was designed to investigate the anticancer potential of Taraxastane against human cervical cancer cells.

Methods: MTT assay and DAPI staining were used for determining the cell viability. DCFH-DA and DiOC6 based estimations were employed for determination of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP), respectively. Flow cytometry technique was used for analysis of cell cycle and necrosis. Analysis of cell migration and invasion was performed by wound heal and transwell assays, repectively. Protein expression was analyzed by Western blotting.

Results: MTT assay showed that Taraxastane inhibited the proliferation of DoTc2 cervical cancer cells in a concentration-dependent manner with an IC50 of 20μM, whereas it had lesser effect on the proliferation of normal human cervical cells. The molecule was seen to increase the ROS concentration along with decreasing MMP. Flow cytometry showed that Taraxastane didn't induce cell apoptosis in DoTc2 cells and anticancer effects were mainly in the form of DoTc2 cell necrosis. This was also evident from the western blot analysis of Bax and BCl-2 proteins whose concentration remained unchanged under Taraxastane treatment. Taraxastane treatment led to cell cycle arrest at G2/M checkpoint without any effect on Cyclin D protein expression. Western blotting of JNK and p-38 proteins showed that Taraxastane blocks the JNK/MAPK signaling pathway by preventing the phosphorylation of the former in a dose-dependent manner. Finally, the wound healing and transwell assays showed that Taraxastane inhibited the migration and invasion of cervical cancer cells, which indicates the role of Taraxastane in the prevention of cancer metastasis.

Conclusion: To conclude, Taraxastane has remarkable anti- proliferative effect on human cervical cancer cells and thus may prove as a vital lead molecule for discovery of anticancer drugs.