Molecular Transporters for Drug and Probe Delivery
The unmet need for effective delivery technologies for drugs and diagnostics comprises one of the most exciting areas of opportunity at the interface of chemistry, biology, materials science and medicine. In 2000, our lab first described the molecular requirements for uptake across biological barriers, showing that guanidinium-rich molecular transporters enable or enhance the passage of otherwise impermeable cargo across the cellular membrane. Since our seminal report, we and others have shown that many cargo types can be delivered across a variety of biological barriers, including tissues and even human skin. Efforts in our lab have expanded from the delivery of small molecules to peptides, proteins, plasmid DNA and other oligonucleotides. Importantly, our function-oriented studies have enabled us to think beyond the confines of peptidic agents to design new and even more effective nonpeptidic molecular transporters.
Inspired by Nature: Guanidinium groups enable cellular uptake
Our observation that cellular uptake of Tat was directly related to the number of arginines led to the design of the first non-natural guanidinium-rich molecular transporters that outperformed Tat.
Work within our group highlights the utility of “releasable” conjugates, wherein a drug or probe is attached to the transporter via a chemical linker designed to be cleaved under specific biochemical conditions. A redox-releasable disulfide linker is cleaved by intracellular glutathione, followed by intramolecular cyclization to release free drug.
Guanidinium-rich Transporters Evade Pgp-mediated Efflux
and Overcome Multidrug Resistance
Octaarginine-Taxol conjugates have been shown to overcome resistance to Taxol in Taxol-resistant ovarian carcinoma cells. This approach to overcoming multidrug resistance was demonstrated in animal models of ovarian cancer and in ex vivo human ovarian cancer patient samples.
Oligomerization-based Strategies for Guanidinium-rich transporters
Recent work, in collaboration with the Waymouth lab at Stanford and the Hedrick lab at IBM, involves the development of a single-step, organocatalytic ring-opening oligomerization to access a novel class of carbonate-based molecular transporters. This flexible, step-economical synthesis allows access to various lengths of transporters with concomitant attachment of a probe or therapeutic cargo.
It has been further advanced for the synthesis of biodegradable block co-oligomers that effectively non-covalently complex and deliver siRNA into cells and degrade under physiological conditions to non-toxic components.
Beyond Mammalian Cells: Talking with Algae
Beyond animal cells, an additional delivery barrier we have begun to study, in conjunction with Lawrence Berkeley National Labs, is the algal cell wall in an effort towards understanding of how algal synthetic machinery can be modified for the more efficient production of biofuels and synthetic building blocks.
References
Seminal Report:
Wender, P. A.; Mitchell, D. J.; Pattabiraman, K.; Pelkey, E. T.; Steinman, L.; Rothbard, J. B. The Design, Synthesis, and Evaluation of Molecules That Enable or Enhance Cellular Uptake: Peptoid Molecular Transporters. Proc. Natl. Acad. Sci. U.S.A. 2000, 97, 13003–13008. Number and array of guanidiniums responsible for cellular uptake of HIV-1 Tat; first designed guanidinium-rich, cell-penetrating molecular transporter.
Lead references:
Wender, P. A.; Mitchell, D. J.; Pattabiraman, K.; Pelkey, E. T.; Steinman, L.; Rothbard, J. B. The Design, Synthesis, and Evaluation of Molecules That Enable or Enhance Cellular Uptake: Peptoid Molecular Transporters. Proc. Natl. Acad. Sci. U.S.A. 2000, 97, 13003–13008. Number and array of guanidiniums responsible for cellular uptake of HIV-1 Tat; first designed guanidinium-rich, cell-penetrating molecular transporter.
Lead references:
- Stanzl, E. G.; Trantow, B. M.; Vargas, J. R.; Wender, P. A. Fifteen Years of Cell-Penetrating, Guanidinium-Rich Molecular Transporters: Basic Science, Research Tools, and Clinical Applications. Acc. Chem. Res. 2013. ASAP. DOI: 10.1021/ar4000554
- Geihe, E. I.; Cooley, C. B.; Simon, J. R.; Kiesewetter, M. K.; Edward, J. A.; Hickerson, R. P.; Kaspar, R. L.; Hedrick, J. L.; Waymouth, R. M.; Wender, P. A. Designed guanidinium-rich amphipathic oligocarbonate molecular transporters complex, deliver and release siRNA in cells. Proc. Natl. Acad. Sci. U.S.A. 2012, 109, 13171–13176.
- Hyman, J. M.; Geihe, E. I.; Trantow, B. M.; Parvin, B.; Wender, P. A. A molecular method for the delivery of small molecules and proteins across the cell wall of algae using molecular transporters. Proc. Natl. Acad. Sci. U.S.A. 2012, 109, 13225–13230.
- Wender, P. A.; Galliher, W. C.; Bhat, N. M.; Pillow, T. H.; Bieber, M. M.; Teng, N. N. H. Taxol-oligoarginine conjugates overcome drug resistance in-vitro in human ovarian carcinoma. Gynecologic Oncology 2012, 126, 118–123.
- Cooley, C.B.; Trantow, B.M.; Nederberg, F.; Kiesewetter M.K.; Hedrick, J.L.; Waymouth, R.M.; Wender, P.A.. Oligocarbonate Molecular Transporters: Oligomerization-Based Syntheses and Cell-Penetrating Studies. J. Am. Chem. Soc. 2009, 131, 16401.
- Dubikovskaya, E.A.; Thorne, S.H.; Pillow, T.H.; Contag, C.H.; Wender, P.A. Overcoming Multidrug Resistance of Small-Molecule Therapeutics with Releasable Octaarginine Transporters. Proc. Natl. Acad. Sci. U.S.A. 2008, 105, 12128.
- Wender, P.A.; Galliher, W.; Goun, E.; Jones, L.; Pillow, T. The Design of Guanidinium-rich Transporters and Their Internalization Mechanisms. Adv. Drug Delivery Rev. 2008, 60, 452.
- Wender, Paul A.; Elena A. Goun, Lisa R. Jones, Thomas H. Pillow, Jonathan B. Rothbard, Rajesh Shinde, and Christopher H. Contag. Real-time Analysis of Uptake and Bioactivatable Cleavage of Luciferin-Transporter Conjugates in Transgenic Reporter Mice. Proc. Natl. Acad. Sci. U.S.A 2007, 104, 10340-10345.
- Jones, L. R.; Goun, E. A.; Shinde, R.; Rothbard, J. B.; Contag, C. H.; Wender, P. A. Releasable Luciferin-Transporter Conjugates: Tools for the Real-Time Analysis of Cellular Uptake and Release. J. Am. Chem. Soc. 2006, 128, 6526-6527.
- Rothbard, J. B.; Jessop, T. C.; Lewis, R. S.; Murray, B. A.; Wender, P. A. Role of Membrane Potential and Hydrogen Bonding in the Mechanism of Translocation of Guanidinium-Rich Peptides into Cells. J. Am. Chem. Soc. 2004, 126, 9506–9507.
- Rothbard, J. B.; Garlington, S.; Lin, Q.; Kirschberg, T.; Kreider, E.; McGrane, P. L.; Wender, P. A.; Khavari, P. A. Conjugation of arginine oligomers to cyclosporin A facilitates topical delivery and inhibition of inflammation. Nature Medicine 2000, 6, 1253–1257.