Liang Wang1, Judy Y W Chan1, Juciane V Rêgo2, Cheong-Meng Chong1, Nana Ai1, Cláudio B Falcão3, Gandhi Rádis-Baptista4, Simon M Y Lee5. 1. State Key Laboratory of Quality Research in Chinese Medicine and Institute of Chinese Medical Sciences, University of Macau, Macao, China. 2. Northeast Biotechnology Network (RENORBIO), Post-graduation program in Biotechnology, Federal University of Ceara, Brazil; Laboratory of Biochemistry and Biotechnology, Institute for Marine Sciences, Federal University of Ceara, Brazil. 3. Laboratory of Biochemistry and Biotechnology, Institute for Marine Sciences, Federal University of Ceara, Brazil. 4. Laboratory of Biochemistry and Biotechnology, Institute for Marine Sciences, Federal University of Ceara, Brazil. Electronic address: gandhi.radis@ufc.br. 5. State Key Laboratory of Quality Research in Chinese Medicine and Institute of Chinese Medical Sciences, University of Macau, Macao, China. Electronic address: simonlee@umac.mo.
Abstract
BACKGROUND: Animal venoms contain a diverse array of proteins and enzymes that are toxic toward various physiological systems. However, there are also some practical medicinal uses for these toxins including use as anti-bacterial and anti-tumor agents. METHODS: In this study, we identified a nine-residue cryptic oligopeptide, KRFKKFFKK (EVP50) that is repeatedly encoded in tandem within vipericidin sequences. RESULTS: EVP50 displayed in vivo potent lethal toxicity to zebrafish larvae (LD50=6 μM) when the peptide's N-terminus was chemically conjugated to rhodamine B (RhoB). In vitro, RhoB-conjugated EVP50 (RhoB-EVP50) exhibited a concentration-dependent cytotoxic effect toward MCF-7 and MDA-MB-231 breast cancer cells. In MCF-7 cells, the RhoB-EVP50 nonapeptide accumulated inside the cells within minutes. In the cytoplasm, the RhoB-EVP50 induced extracellular calcium influx and intracellular calcium release. Membrane budding was also observed after incubation with micromolar concentrations of the fluorescent EVP50 conjugate. CONCLUSIONS: The conjugate's interference with calcium homeostasis, its intracellular accumulation and its induced membrane dysfunction (budding and vacuolization) seem to act in concert to disrupt the cell circuitry. Contrastively, unconjugated EVP50 peptide did not display neither toxic nor cytotoxic activities in our in vivo and in vitro models. GENERAL SIGNIFICANCE: The synergic mechanism of toxicity was restricted to the structurally modified encrypted vipericidin nonapeptide.
BACKGROUND: Animal venoms contain a diverse array of proteins and enzymes that are toxic toward various physiological systems. However, there are also some practical medicinal uses for these toxins including use as anti-bacterial and anti-tumor agents. METHODS: In this study, we identified a nine-residue cryptic oligopeptide, KRFKKFFKK (EVP50) that is repeatedly encoded in tandem within vipericidin sequences. RESULTS: EVP50 displayed in vivo potent lethal toxicity to zebrafish larvae (LD50=6 μM) when the peptide's N-terminus was chemically conjugated to rhodamine B (RhoB). In vitro, RhoB-conjugated EVP50 (RhoB-EVP50) exhibited a concentration-dependent cytotoxic effect toward MCF-7 and MDA-MB-231 breast cancer cells. In MCF-7 cells, the RhoB-EVP50 nonapeptide accumulated inside the cells within minutes. In the cytoplasm, the RhoB-EVP50 induced extracellular calcium influx and intracellular calcium release. Membrane budding was also observed after incubation with micromolar concentrations of the fluorescent EVP50 conjugate. CONCLUSIONS: The conjugate's interference with calcium homeostasis, its intracellular accumulation and its induced membrane dysfunction (budding and vacuolization) seem to act in concert to disrupt the cell circuitry. Contrastively, unconjugated EVP50 peptide did not display neither toxic nor cytotoxic activities in our in vivo and in vitro models. GENERAL SIGNIFICANCE: The synergic mechanism of toxicity was restricted to the structurally modified encrypted vipericidin nonapeptide.
Authors: Irina Kerkis; Alvaro Rossan de Brandão Prieto da Silva; Celine Pompeia; Jan Tytgat; Paulo L de Sá Junior Journal: Cell Mol Life Sci Date: 2016-08-23 Impact factor: 9.261
Authors: Nelson G J Oliveira; Marlon H Cardoso; Nadya Velikova; Marcel Giesbers; Jerry M Wells; Taia M B Rezende; Renko de Vries; Octávio L Franco Journal: Sci Rep Date: 2020-06-04 Impact factor: 4.379