The toxin component of targeted anti‐tumor toxins determines their efficacy increase by saponins

Abstract

Saponin Targeted toxin A B S T R A C TTumor-targeting protein toxins are composed of a toxic enzyme coupled to a specific cell binding domain that targets cancer-associated antigens. The anti-tumor treatment by targeted toxins is accompanied by dose-limiting side effects. The future prospects of targeted toxins for therapeutic use in humans will be determined by reduce side effects. Certain plant secondary metabolites (saponins) were shown to increase the efficacy of a particular epidermal growth factor receptor (EGFR)-targeted toxin, paralleled by a tremendous decrease of side effects.This study was conducted in order to investigate the effects of substituting different toxin moieties fused to an EGF ligand binding domain on the augmentative ability of saponins for each against therapeutic potential of the saponin-mediated efficacy increase for different anti-tumor toxins targeting the EGFR.We designed several EGFR-targeted toxins varying in the toxic moiety. Each targeted toxin was used in combination with a purified saponin (SA1641), isolated from the ornamental plant Gypsophila paniculata L. SA1641 was characterized and the SA1641-mediated efficacy increase was investigated on EGFR-transfected NIH-3T3 cells.We observed a high dependency of the SA1641-mediated efficacy increase on the nature of toxin used for the construction of the targeted toxin, indicating high specificity.Structural alignments revealed a high homology between saporin and dianthin-30, the two toxic moieties that benefit most from the combination with SA1641.We further demonstrate that SA1641 did not influence the plasma membrane permeability,

Saponins modulate the intracellular trafficking of protein toxins

“…SA1641 and SA1657 were analyzed by an Agilent 6210 ESI-TOF-MS. Scans were performed in negative mode (m/z 1641.7312 and m/z 1657.7312) (see supplemental information). SA1641 and SA1657 were analyzed by extensive one and two dimensional NMRspectroscopy [11].…”

“…N-glycosidase activity of Alexa-Fluor labeled saporin ( Alexa saporin) was determined using Herring sperm DNA as a substrate and is described in detail elsewhere [11].…”

“…It was reported that at a low concentration the triterpenoid saponins drastically augment the cytotoxicity of saporin, saporin based targeted toxins [11] and related toxins such as agrostin [12]. Agrostin is also a type I ribosome inactivating protein, that is present in the seeds of the plant Agrostemma githago L. It is also worth mentioning, that Agrostemma githago L. biosynthesizes triterpenoid saponins that enhance the cytotoxicity of agrostin [13].…”

A novel antitumor compound nobiliside D isolated from sea cucumber (Holothuria nobilis Selenka)

“…The novel compound was identified as the saponin family member nobiliside D. This extraction method achieves simultaneous extraction from H. nobilis Selenka, as well as improving the extraction efficiency and shortening the time of purification. Saponins are established to have anti-tumor activity (13,14). Saponins are the main metabolites of sea cucumber (5,6) and currently >10 types of saponin have been isolated and purified (15,16).…”

Diving through Membranes: Molecular Cunning to Enforce the Endosomal Escape of Antibody-Targeted Anti-Tumor Toxins

“…These saponins increase the specific cytotoxicity of targeted saporin molecules, dependent on the cell line, by up to more than 100,000-fold in vitro, and up to 300-fold in vivo [29,100,101]. The effect is based on a poorly understood interaction between a few particular saponin species out of many thousands and the plant Type-I-RIPs saporin and dianthin [102]. Surface plasmon resonance measurements point to a transient binding of saponins to the toxin components of targeted toxins in a pH-dependent manner [103].…”