Abstract
Recent research has paid increasing attention to antimicrobial peptides (AMPs), not only for their antimicrobial activity, but also for their potential of therapeutic application in cancer therapy. In the past few years, our lab has found several novel bacteriocins including m2163 and m2386 with anticancer potential from Lactobacillus casei ATCC 334. In this thesis, two directions of research were simultaneously processed. On one hand, to design stronger anticancer peptides, several modifications of both m2163 and m2386 were made following the principle, and went through preliminary tests. On the other hand, we focused on characterization and the anti-proliferative study of the membrane disrupting peptide KL15, a short peptide which was earlier modified from m2163. KL15 is an AMP with anticancer activity. In the cytotoxicity assay, both cancerous- human colon adenocarcinoma cell lines, SW480 and Caco-2, showed a more obvious decrease on survival rate than non-cancerous- human mammary epithelial cell line, H184B5F5/M10; IC50 of SW480 and Caco-2 are around 50 μg/ml (26.3 μM), while IC50 of H184B5F5 is at 150 μg/ml. SW480 cell changes after treated with KL15 were observed in three aspects- DNA, membrane permeability and morphology, and possible cell death pathway. Also, combined with confocal microscope, we knew that KL15 would enter the cell as membrane permeability increase in the later stage. The overall results implied that the cell membrane disruption causing by KL15 played a crucial role in cell death, moreover, the concerning cell death pathway may be necrosis. However, the underlying mechanism is not yet clear, and is still under investigation.