EXPRESSION, PURIFICATION, AND CHARACTERIZATION OF RGD-mda-7, A HIS-TAGGED mda-7/IL-24 MUTANT PROTEIN

Abstract

RGD peptide (Arg-Gly-Asp tripeptide) binds to integrin αVβ3 and αVβ5, which is selectively expressed in tumor neovasculature and on the surface of some tumor cells. Some studies showed that coupling the RGD peptides to anticancer drugs yielded compounds with increased efficiency against tumors and lowered toxicity to normal tissues. The melanoma differentiation-associated gene-7/interleukin-24 gene (mda-7/IL-24) is a novel tumor-suppressor/cytokine gene that exhibits potent tumor-suppressive activity without damaging normal cells. To enhance the antitumor effect, we inserted a glycine residue into the wild type (mda-7/IL-24) between 164Arg and 165Asp to form a RGD peptide, named RGD-mda-7, then expressed RGD-mda-7 in Escherichia coli. Herein, we describe the expression and purification of RGD-mda-7. We detected the characterizations of immunostimulatory activity, tumor targeting, potent cytopathic effect, and apoptosis inducing exploited by RGD-mda-7 in tumor cells, and also compared these characterizations with wtmda-7/IL-24. The data showed that RGD-mda-7 had more potent tumor targeting and apoptosis-inducing effects than wtmda-7/IL-24.