20.109(F09): Omar Abudayyeh and Pablo Crespo Research Proposal

Engineering phages to target tumors

Omar Abudayyeh and Pablo Crespo

Project Overview

This project aims to engineer phages that are able to selectively target cancer cells in vitro and deliver cargo that can result in tumor death. Because phages have multiple types of proteins on their outer coat, the phages can be designed to bind to other substrates, such as drugs or gold, in addition to the tumor. This allows for targeted delivery of drugs or for photothermal cancer therapy through irradiation of the gold.

Research Problem and Goals

The goal of this project is to develop phages that can be used as constructs for delivering cargo to tumors in mice. As with gold nanoparticles, phages offer a construct for modifiable attachment of cargo, such as drugs or gold, for delivery to tumors. Phages can have benefits, however, such as longer circulation times due to their shape. Moreover, while nanoparticles require ligands that bind to known tumor-associated antigens, with phages we only need to screen a phage library to isolate phages that selectively bind to tumors. In addition to designing phages that can bind to both tumors and cargo, including drugs and gold, we will test their therapeutic effect in mice and attempt to increase phage circulation time using polyethylene glycol (PEG).

References

• Krag, D., Shukla, G., Shen, G., Pero, S., Ashikaga, T., Fuller, S., Weaver, D., Burdette-Radoux S., & Thomas, C. Selection of tumor-binding ligands in cancer patients with phage display libraries. Cancer Research. 2006; 66: 7724-7733.

The researchers used phage display libraries to identify ligands that could be used for targeting cancer, including breast, melanoma, and pancreas. Repeated panning was done by allowing phages to hone in on tumors in patients with stage IV cancer and then excising the tumors and recovering phages that bound. The study identified several motifs on the binding peptide indicating nonrandom specificity for tumors.

• Huang X., El-Sayed, I., Qian, W., & El-Sayed, M. Cancer cell-imaging and photothermal therapy in the near-infrared region by using gold nanorods. J. of the Am. Chem. Soc. 2005; 128: 2115-2120.

Gold nanorods conjugated to anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibodies are able to selectively bind to malignant epithelial cancer cells. Using near-infrared radiation (~800nm), the gold nanorods can be used simultaneously for imaging and for photothermally destroying the cancer cells.

• Maltzahn, G., Park, J., Agrawal, A., Bandaru, N., Das, S., Sailor, M., & Bhatia, S. Computationally guided photothermal tumor therapy using long-circulating gold nanorod atennas. Cancer Research. 2009; 69: 3892-3900.

Polyethylene glycol (PEG)-coated gold nanorods enabled photothermal destruction of irradiated tumors in mice. In addition, the PEG allowed the gold nanorods to have a circulation half-life in vivo of ~17 hours, significantly higher than previously found half-lives of ~4 hours.

• Potineni, A., Lynn, D., Langer, R., & Amiji, M. Poly(ethylene oxide)-modified poly(B-amino ester) nanoparticles as a pH-sensitive bioedegradable system for paclitaxel delivery. Journal of Controlled Release. 2003; 2002: 223-234.

Polymer nanoparticles were successfully able to deliver the drug paclitaxel to cancer cells. Paclitaxel, which has cytotoxic effects for tumor cells, was encapsulated in the polymer nanoparticle made of poly(ethylene oxide)-modified poly(B-amino ester). Because this polymer becomes readily soluble at a pH below 6.5, it is able to release the encapsulated drug inside tumor cells, which have an unusually low pH of about 6.0 due to an aberrant metabolism caused by poor oxygen perfusion.

• Huang, Y., Chiang, C.-Y., Lee, S. K., Gao, Y., Hu, E. L., De Yoreo, J., et al. Programmable Assembly of Nanoarchitectures Using Genetically Engineered Viruses. NANO LETTERS. 2005; 5(7): 1429-1434.

and Nam, K. T., Peelle, B. R., Lee, S.-W., & Belcher, A. M. Genetically Driven Assembly of Nanorings Based on the M13 Virus. NANO LETTERS. 2004; 4: 23-28.

Both explain how to use DNA engineering to make M13 phage capable of binding with specific materials, such as gold. DNA libraries of p3 and p8 protein mutants were screened individually to select for mutants that would bind to streptavidin and gold respectively. This study suggests possible assembly of a phage that could bind to specific materials by altering its p3 and p8 genome sequence.

• Dobrovolskaia MA, Aggarwal P, Hall JB, & McNeil SE. Preclinical studies to understand nanoparticle interaction with the immune system and its potential effects on nanoparticle biodistribution. Molecular Pharmaceutics. 2008; 5(4): 487-495.

This study explains some of the major flaws with nanoparticle drug delivery systems. The immune system can detect the nanoparticles and eliminate them. The study also mentions other factors such as cytotoxicity and circulation time in the blood. In vivo methods to test nanoparticles under the presence of immune system response are presented as well.

• Souza GR, Christianson DR, Staquicini FI, Ozawa MG, Snyder EY, Sidman RL, et al. Networks of gold nanoparticles and bacteriophage as biological sensors and cell-targeting agents. Proceedings of the National Academy of Sciences of the United States of America. 2006; 103(5): 1215-1220.

An engineered network composed of a phage and gold nanoparticles was created and modified for biomedical purposes. A specific modification made the network susceptible to near-infrared photon to heat conversion which is something we are interested in using for our design proposal.

• Yacoby I, Bar H, & Benhar I. Targeted drug-carrying bacteriophages as antibacterial nanomedicines. Antimicrobial Agents and Chemotherapy. 2007; 51(6): 2156-2163.

This study tries to create a site-specific antibiotic carrying system. It uses the specificity that can be attained by the phages and uses them as carriers of a specific drug. Aminoglycoside antibiotics were used to enhance the carrying ability of the phages and inhibit growth of Streptococcus pyogenes and E.coli. This system proved to be much more effective than drugs alone.

• Li WX, & Franklin WA. Radiation- and heat-induced apoptosis in PC-3 prostate cancer cells. Radiation Research. 1998; 150(2): 190-194.

This study proved that prostate cancer cells underwent apoptosis under the presence of heat. These cells do not respond well to radiation treatment, so heat might be a better way to induce apoptosis. A temperature of 43C or higher was found to be essential for apoptosis to happen in a feasible amount of time.