Synthesis of the ensembles from succinylated interleukin-2 derivatives and their biological activity in vitro

<p><strong>Purpose: </strong>The biological activity (direct anticancer action in vitro) of combinatorial IL-2 succinylated derivatives was examined. Acylation of IL-2 was performed using succinic anhydride with various levels of acylation, with the formation of a complex assembly of many derivatives (self-assembled quasi-living structure).</p><p><strong>Methods: </strong>In the study, we used recombinant interleukin-2 (IL-2) (Ronkoleukin, Russia) in oxidizing form and other reagents from Sigma-Aldrich and Fluka (USA). For acylation, recombinant IL-2 in the form of a matrix fluid with a protein concentration of 0.6 mg/ml was used. The IL-2 matrix solution was brought to a pH of 8.0 through the addition of a 0.01% solution of sodium hydroxide. The synthesized ensemble of succinyl-IL-2 was analyzed using the capillary gel electrophoresis method in an Agilent-2100 bioanalyzer. The molecular masses of the synthesized ensemble were established in comparison to standard samples of low-molecular proteins with known molecular masses that were part of the bioanalyzer’s collection. The additional negative charge of the modified IL-2 was determined by a FPLC (Fast Protein Liquid Chromatography) system from Pharmacia (Woerden, Netherlands). CTLL-2, a murine IL-2-dependent cell line, was obtained fromBiokontrol (Kiev, Ukraine). These respondingcells were used in proliferative assays comparing the activityof the IL-2 and succinylated IL-2 derivatives to the WHO InternationalStandard. For statistical data analysis, the one-way ANOVA was used.</p><p><strong>Results</strong><strong>: </strong>After treatment with Suc-IL-2, BTL were studied in vitro on the CTLL-2 cell line, dose-dependently, in a BTL induction reaction. The highest level of biological activity in acylated IL-2 was observed in Suc-IL-2 with four modified lysine residues. In conclusion, succinylated IL-2 with four substituted lysines may be useful as a prospective anticancer agent.</p><p><strong>Conclusions</strong><strong>: </strong>Ten-fold increase in the biological activity of IL-2 was observed after partial succinylation. This phenomenon can be used in the further IL-2 drugs biotechnological development for increasing the concentration of the main active substance in medicinal form