ABSTRACT
The present work investigated the effects of the nematocysts venom (NV) from the Chrysaora helvola Brandt (C. helvola) jellyfish on the human nasopharyngeal carcinoma cell line, CNE-2. The medium lethal concentration (LC50), quantified by MTT assays, was 1.7 ± 0.53 µg/mL (n = 5). An atypical apoptosis-like cell death was confirmed by LDH release assay and Annexin V-FITC/PI staining-based flow cytometry. Interestingly, activation of caspase-4 other than caspase-3, -8, -9 and -1 was observed. Moreover, the NV stimuli caused a time-dependent loss of mitochondrial membrane potential (ΔΨm) as was an intracellular ROS burst. These results indicated that there was uncoupling of oxidative phosphorylation (UOP). An examination of the intracellular pH value by a pH-sensitive fluorescent probe, BCECF, suggested that the UOP was due to the time-dependent increase in the intracellular pH. This is the first report that jellyfish venom can induce UOP.
Subject(s)
Antineoplastic Agents/pharmacology , Cnidarian Venoms/pharmacology , Drug Discovery , Nasopharyngeal Neoplasms/drug therapy , Oxidative Phosphorylation/drug effects , Scyphozoa/chemistry , Uncoupling Agents/pharmacology , Animals , Antineoplastic Agents/isolation & purification , Apoptosis/drug effects , Carcinoma/drug therapy , Carcinoma/metabolism , Cell Line, Tumor , Cell Survival/drug effects , China , Cnidarian Venoms/isolation & purification , Humans , Hydrogen-Ion Concentration , Kinetics , Lethal Dose 50 , Membrane Potential, Mitochondrial/drug effects , Nasopharyngeal Neoplasms/metabolism , Nematocyst/chemistry , Nematocyst/growth & development , Pacific Ocean , Reactive Oxygen Species/agonists , Reactive Oxygen Species/metabolism , Respiratory Mucosa/drug effects , Scyphozoa/growth & development , Uncoupling Agents/isolation & purificationABSTRACT
The present work investigated the in vitro cytotoxicity of nematocyst venom (NV) from Chrysaora helvola Brandt (C. helvola) jellyfish against human MCF-7 and CNE-2 tumor cell lines. Potent cytotoxicity was quantified using the MTT assay (LC50=12.07±3.13 and 1.6±0.22µg/mL (n=4), respectively). Apoptosis-like cell death was further confirmed using the LDH release assay and Annexin V/PI double staining-based flow cytometry analysis. However, only activation of caspase-4 was observed. It is possible that some caspase-independent pathways were activated by the NV treatment. Since no reference or antivenom is available, the effects of several commonly used antidotes on the cytotoxicity of NV were examined on more sensitive CNE-2 cells to determine the appropriate emergency measures for envenomation by C. helvola. The phospholipase A2 (PLA2) inhibitor para-bromophenacyl bromide (pBPB) showed no protective effect, while Mg(2+) potentiated cytotoxicity. Voltage-gated L-type Ca(2+) channel blockers (verapamil, nifedipine and felodipine) and Na-Ca(2+) exchanger inhibitor KB-R7943 also showed no effect. Assays using Ca(2+)-free culture media or the intracellular Ca(2+) chelator BAPTA also could not inhibit the cytotoxicity. Taken together, these results suggest that PLA2 and Ca(2+) are not directly involved in the cytotoxicity of NV from C. helvola. Our work also suggests caution regarding the choice for first aid for envenomation by C. helvola jellyfish.