Activity of protegrin-1 against mouse Ehrlich ascites carcinoma in vitro and in vivo

Introduction. The problem of multidrug resistance in cancer treatment creates an urgent demand for developing new effective antitumor agents. Due to the unusual mechanism of recognizing and damaging tumor cells, antimicrobial peptides (AMPs) are considered as possible prototypes for designing such therapeutics.

Aim. This work was aimed to compare the antitumor potential of the promising membranolytic AMP protegrin-1 (PG-1) in vitro and in vivo in Ehrlich ascites carcinoma (EAC) mice model.

Methods. We used two variants of the model by inducing a tumor in solid or ascites form. In the first case, the mice were injected with the peptide twice a week for three weeks, and in the second injections were provided every other day for six days. The activity of AMPs against isolated EAC cells in vitro was analyzed using MTT-test.

Results. PG-1 demonstrated high activity against EAC cells in vitro, but had no significant effect on the lifespan of mice bearing solid or ascites form of EAC tumor at the dosing and administration regimens we used. However, treatment with PG-1 caused a decrease in the ascites volume and in the number of cells in the ascites fluid.

Conclusion. PG-1 retains its antitumor properties in vivo, but it may be presumed, that to effectively suppress tumor growth it requires a more frequent and prolonged administration compared with conventional antitumor antibiotics, of which we adopted the administration regimen for PG-1 in this study.