Chloroform extract of Tibetan herbal medicine Dracocephalum tanguticum Maxim. inhibits proliferation of T98G glioblastomas cells by modulating Caspase-3 cleavage and expression of Bax and p21

A chloroform extract of Dracocephalum tanguticum Maxim. (CEDtM) was obtained and phytochemical analysis showed that this extract contained high content of sapogenin or saponin (53.7%). Subsequently, the anticancer potential of this CEDtM was investigated in T98G glioblastomas cells. Results showed that CEDtM with the dose of 90 mu g/ml efficiently induced cytotoxicity in T98G cells but had little cytotoxic effect on mouse primary fibroblast cells. The T98G cells treated with CEDtM showed the features of apoptosis as cell-volume shrinkage, cell blebbing, cell detachment and apoptotic bodies. Moreover, treatment of CEDtM stimulated Caspase-3 cleavage and the expression of proapoptotic protein Bax in T98G cells. Interestingly, CEDtM inhibited the expression of p21 protein, a cell cycle inhibitor, with induction of T98G apoptosis. These findings suggest that CEDtM selectively inhibits T98G glioblastomas cell proliferation by induction of cell apoptosis via Caspase-3 and Bax pathways, along with an inhibition of p21.