Enhancement of the cytolytic effect of anti-bacterial cecropin by the microvilli of cancer cells

A comparison between IC₅₀s of cecropin B on tumor cells such as KG-1 leukemia and Ags stomach carcinoma and non-tumor cells like fibroblasts and red blood cells was conducted. The IC₅₀s of cecropin B for KG-1 leukemia and Ags carcinoma cells were 20.8 ± 2.3 μM (MTT) and 18.9 ± 3.3 μM (trypan blue) and 16.0 ± 3.5 μM (MTT) and 15.3 ± 3.7 μM (trypan blue), respectively. The IC₅₀ of cecropin B for 3T6 fibroblast cells was 92.0 ± 9.1 μM by MTT assay and the HE₅₀ of cecropin B for human red blood cells was 1 80.0 ± 20.1 μM at OD(414nm). The cytolysis induced by cecropin peptides was more effective for the cancer cells than for the normal cells. Based on the observations from scanning electron microscopy, this may mainly due to the cancer cells having a high population of the irregular microvilli on the cell surface. Since peptides bound to the cell membrane are non-specific, the attraction of peptides by microvilli may be one of the main driving forces before the lysis in membrane bilayers can be efficiently initiated.