Cytotoxicity of crotoxin on murine erythroleukemia cellsin vitro

Abstract

The cytotoxic effect of crotoxin, a heterodimeric phospholipase A2 from the venom of Crotalus durissus terrificus, was examined on murine erythroleukemia cells in vitro. Crotoxin cytocidal effect on cell growth had an EC50 of approximately 0.1-0.2 microM (3.0-5.0 micrograms/ml) in serum-free medium. Cytotoxicity was independent of cell growth since both quiescent and proliferating cells had similar sensitivities to the toxin. Dissociation of the crotoxin complex and phospholipase A2 activity of its subunit B are required for cytotoxicity, since the covalently linked crotoxin complex or the specific alkylation of the active site on the subunit B abolish the cytotoxic activity on murine erythroleukemia cells. Specific interaction between crotoxin and murine erythroleukemia cells appears to be required since the homologous phospholipase A2 from Crotalus atrox venom, with a higher phospholipase A2 specific activity than crotoxin, was 86-fold less potent than crotoxin. The data in this report show that the cytotoxic effect of crotoxin on murine erythroleukemia cells is consistent with the specific binding of the toxin resulting in cytocidal action mediated by the phospholipase A2 activity of crotoxin subunit B.

Autophagy is involved in cytotoxic effects of crotoxin in human breast cancer cell line MCF-7 cells

“…CrTX is a potent antitumor agent and displays cytotoxic activity against a variety of murine and human tumor cell lines in vitro [15,16] . It requires both the PLA 2 activity of subunit B [15] and the ability of the complex to dissociate into their subunits [15,29] .…”

“…It requires both the PLA 2 activity of subunit B [15] and the ability of the complex to dissociate into their subunits [15,29] . CrTX-induced cytotoxic effects appear to be highly active in cell lines expressing a high density of EGFR [17] , thus suggesting that EGFR, or a receptor function, play a role in targeting.…”

“…Its cytotoxicity was independent of cell growth since both quiescent and proliferating cells had similar sensitivities. CrTX displays cytotoxic activity against a variety of murine [15] and human tumor cell lines in vitro [16] and appears to be highly active toward cell lines expressing a high density of epidermal growth factor receptors (EGFR) [17] ; however, the precise mechanism of the cytotoxicity remains to be determined. It had previously been assumed that the toxin simply induces lysis through the disruption of the cell membrane.…”

Crotoxin enhances the antitumor activity of gefinitib (Iressa) in SK-MES-1 human lung squamous carcinoma cells

“…CrTX also exerts an anti-inflammatory/analgesic activity seemingly through the lipoxygenase pathway without negatively impacting its anticancer activity. For both functions, CrTX requires the PLA2 activity of subunit B and the ability of the complex to dissociate into its subunits (9,16). Antitumor inhibition in vivo of 83% has been demonstrated against Lewis lung carcinoma (17) and MX-1 human mammary carcinoma (69% growth inhibition).…”

Crotoxin suppresses the tumorigenic properties and enhances the antitumor activity of Iressa® (gefinitib) in human lung adenocarcinoma SPCA-1 cells

“…The biological activities of CrTX include neurotoxicity, immunomodulatory, anti-inflammatory, antimicrobial and analgesic actions. Notably, CrTX has demonstrated cytotoxic effects in a variety of human tumor cell lines in vitro, including K562 leukemia cells, MCF-7 breast cancer cells as well as A549 and SK-MES-1 lung cancer cells (7,8). The mechanism underlying the cytotoxic effects of CrTX in A549 and SK-MES-1 lung cancer cells includes cellular proliferation inhibition and apoptosis, associated with activation of caspase-3, c-Jun N-terminal kinase (JNK), p53 and p38.…”