The oligoguanidine transport system: A novel approach to drug delivery.

摘要

The oligoguanidine transport system (OGTS) is a highly conserved system for enabling cellular entry into a wide variety of cell types and tissues. Uptake by this mechanism is apparently energy-dependent and appears to require at least six arginine residues or guanidinium groups. Until recently, the utility of this transport system was virtually unexplored in regard to promoting cellular uptake of therapeutic agents. The benefit of such a vehicle for drug delivery is two-fold; first, the nature of the transport peptide imparts on the attached cargo a dramatically enhanced aqueous solubility that enables drug administrations without the use of adjuvants or excipients; second it provides a non-invasive method for the delivery of potential therapeutic agents that could not otherwise cross the plasma membrane to interact with their subcellular targets.; Application the OGTS transporters to Taxol provides an example of how this technology can be used to ameliorate issues related to drug formulation by increasing the compound's native water solubility without compromising its cellular uptake. In addition, the OGTS has been employed to enable the uptake of a water soluble, cell-impermeable PKC-ϵ peptide agonist, ϵV1-7. Conjugation of the peptide drug to the transport peptide was accomplished through a readily reducible cysteine-cysteine disulfide bond. As anticipated, the cargo efficiently delivered and released both as evidenced by a dramatic reduction in hypoxia-related cell death.; Finally, attention was turned to the transport system itself and on how it might be further improved. In an effort to increase the number of head groups in contact with the membrane, perturbations were introduced to the peptide's primary structure in the form of proline residues. Molecular modeling of the resultant construct, RRPRRPRR, suggested that four or possibly five of the six head groups were capable of simultaneously interacting with the surface phosphate groups, a putative action required for uptake. Analysis of this compound in a FACS analysis showed that the proline substituted structure was not only capable of entering cells, but that it was superior to the parent heptamer.