Analysis of caspase3 activation in ChanSu-induced apoptosis of ASTC-a-1 cells by fluorescence techniques

ChanSu(CS), a traditional Chinese medicine, is composed of many chemical compoments. It is isolated from the dried white secretion of the auricular and skin glands of toads, and it has been widely used for treating the heart diseases and other systemic illnesses. However, it is difficult to judge antitumor effect of agents derived from ChanSu and the underlying mechanism of ChanSu inducing cell apoptosis is still unclear. This report was performed to explore the inhibitory effect and mechanism of ChanSu on human lung adenocarcinoma cells (ASTC-a-1). Fluorescence emission spectra and fluorescence resonance energy transfer (FRET) were used to study the caspase-3 activation during the ChanSu-induced human lung adenocarcinoma (ASTC-a-1) cell apoptosis. CCK-8 was used to assay the inhibition of ChanSu on the cell viability. The cells expressing stably with SCAT3 was used to examine if caspase-3 was activated by ChanSu using acceptor photobleaching technique. Our data showed that treatment of ASTC-a-1 cell with ChanSu resulted in the inhibition of viability and induction of apoptosis in a dose-dependent manner and the SCAT3 was almost cleaved 24 h after ChanSu treatment, implying that ChanSu induced cell apoptosis via a caspase-3-dependent death pathway. Our findings extend the knowledge about the cellular signaling mechanisms mediating ChanSu-induced apoptosis.