Effects of camptothecin and hydroxycamptothecin on insect cell lines Sf21 and IOZCAS‐Spex‐II

Abstract

In recent years, concerns over the potential impact of synthetic pesticides on the environment have made the discovery and development of environmentally friendly pesticides a more pressing issue. Camptothecin (CPT) and its derivatives have attracted much attention owing to their unique mechanisms of action against insects. In this paper, two insect cell lines, Sf21 and IOZCAS-Spex-II, were used to conduct a preliminary investigation of the potential of CPT and hydroxycamptothecin (HCPT) as inducers of apoptosis in insect cell lines, and to illustrate the mechanism of action of CPT on insects at the cellular level. The results showed that both CPT and HCPT demonstrate potent cytotoxic effects to the tested insect cell lines in a time- and dose-dependent manner. The DNA fragmentation, activation of caspases and cytochrome c release were observed in both IOZCAS-Spex-II and Sf21 treated with CPT and HCPT. There is no significant difference in cytotoxicity and caspase-3 activation (P < 0.05, except when treated for 2 h) between CPT and HCPT, although the caspase-3 activation was slightly stronger when treated with HCPT in both Sf21 and IOZCAS-Spex-II. The results confirm the existence of the mitochondrial-dependent pathway of apoptosis induced by CPT and HCPT in Sf21 and IOZCAS-Spex-II cell lines. Further investigations are required to reveal the mitochondrial mechanisms and regulation of caspase activation during apoptosis. These studies will provide basic knowledge needed to understand the mechanisms of action of CPT and to develop CPT and its derivatives as insecticides.