RESUMEN
The role of chitinases from the latex of medicinal shrub Calotropis procera on viability of tumor cell lines and inflammation was investigated. Soluble latex proteins were fractionated in a CM Sepharose Fast-Flow Column and the major peak (LPp1) subjected to ion exchange chromatography using a Mono-Q column coupled to an FPLC system. In a first series of experiments, immortalized macrophages were cultured with LPp1 for 24 h. Then, cytotoxicity of chitinase isoforms (LPp1-P1 to P6) was evaluated against HCT-116 (colon carcinoma), OVCAR-8 (ovarian carcinoma), and SF-295 (glioblastoma) tumor cell lines in 96-well plates. Cytotoxic chitinases had its anti-inflammatory potential assessed through the mouse peritonitis model. We have shown that LPp1 was not toxic to macrophages at dosages lower than 125 µg/mL but induced high messenger RNA expression of IL-6, IL1-ß, TNF-α, and iNOs. On the other hand, chitinase isoform LPp1-P4 retained all LPp1 cytotoxic activities against the tumor cell lines with IC50 ranging from 1.2 to 2.9 µg/mL. The intravenous administration of LPp1-P4 to mouse impaired neutrophil infiltration into the peritoneal cavity induced by carrageenan. Although the contents of pro-inflammatory cytokines IL-6, TNF-α, and IL1-ß were high in the bloodstreams, such effect was reverted by administration of iNOs inhibitors NG-nitro-L-arginine methyl ester and aminoguanidine. We conclude that chitinase isoform LPp1-P4 was highly cytotoxic to tumor cell lines and capable to reduce inflammation by an iNOs-derived NO mechanism.
