Novel Strategy Improves Cancer Cell Uptake of Nanoparticles
One of the promises of using nanoparticles to deliver potent anticancer agents to tumors is that it is easy to coat nanoparticles with tumor-targeting molecules that should increase the amount of drug that reaches a tumor while decreasing the amount of drug that hits healthy tissue. Taking this idea one step further, researchers at Harvard Medical School and the Massachusetts Institute of Technology have developed a strategy for identifying what could be called tumor uptake molecules for use on nanoparticles. This new class of tumor-targeting agents boosts the amount of drug-loaded nanoparticles that get into cancer cells.
Omid Farokhzad and Robert Langer, both members of the MIT-Harvard Center for Cancer Nanotechnology Excellence (CCNE), led this study. The researchers published their findings in the journal ACS Nano.
The MIT-Harvard CCNE team focused their discovery efforts on molecules known as aptamers, which are small pieces of RNA or DNA that form three-dimensional shapes capable of binding tightly and specifically to designated targets. In most instances, aptamers are constructed to target a known biomolecule—a disease-associated protein, for example. In this case, the investigators took a different approach and instead targeted two biological properties—the ability to distinguish a prostate cancer cell from a normal prostate cell and the ability to get into the diseased cells. They performed this feat by starting with a huge pool of random RNA sequences and through an iterative process gradually enriched this pool for RNAs that targeted and entered prostate cancer cells. After 12 cycles of this enrichment process, the investigators identified a small number of aptamers that each displayed superior tumor targeting and uptake properties.
The researchers chose one of these aptamers and linked it to a polymer nanoparticle loaded with docetaxel, a potent anticancer agent. Experiments have so far shown that this construct has no effect on normal cells but is highly toxic to prostate cancer cells. The investigators are planning further studies in animal models of prostate cancer. They note that this approach is easily modified to finding targeting and uptake aptamers for any type of cancer cell.
This work, which is detailed in a paper titled, "Engineering of targeted nanoparticles for cancer therapy using internalizing aptamers isolated by cell-uptake selection," was supported in part by the NCI Alliance for Nanotechnology in Cancer, a comprehensive initiative designed to accelerate the application of nanotechnology to the prevention, diagnosis, and treatment of cancer. An abstract of this paper is available at the journal's website.