Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

DNA 'Trojan horse' smuggles drugs into resistant cancer cells

24.02.2016

Cells mistake DNA casing for food, consume drugs and die

Researchers at The Ohio State University are working on a new way to treat drug-resistant cancer that the ancient Greeks would approve of--only it's not a Trojan horse, but DNA that hides the invading force.


This is a rotating view of a single drug-resistant leukemia cell, after it's absorbed DNA nanostructures. Fluorescent markers show that the nanostructures have been taken deep into the cell, into the organelles that will digest them.

Image by Matthew Webber, courtesy of The Ohio State University

In this case, the invading force is a common cancer drug.

In laboratory tests, leukemia cells that had become resistant to the drug absorbed it and died when the drug was hidden in a capsule made of folded up DNA.

Previously, other research groups have used the same packaging technique, known as "DNA origami," to foil drug resistance in solid tumors. This is the first time researchers have shown that the same technique works on drug-resistant leukemia cells.

The researchers have since begun testing the capsule in mice, and hope to move on to human cancer trials within a few years. Their early results appear in the journal Small.

The study involved a pre-clinical model of acute myeloid leukemia (AML) that has developed resistance against the drug daunorubicin. Specifically, when molecules of daunorubicin enter an AML cell, the cell recognizes them and pumps them back out through openings in the cell wall. It's a mechanism of resistance that study co-author John Byrd of The Ohio State University Wexner Medical Center compared to sump pumps that draw water from a basement.

He and Carlos Castro, assistant professor of mechanical engineering, lead a collaboration focused on hiding daunorubicin inside a kind of molecular Trojan horse that can bypass the pumps so they can't eject the drug from the cell.

"Cancer cells have novel ways of resisting drugs, like these pumps, and the exciting part of packaging the drug this way is that we can circumvent those defenses so that the drug accumulates in the cancer cell and causes it to die," said Byrd, a professor of internal medicine and director of the Division of Hematology. "Potentially, we can also tailor these structures to make them deliver drugs selectively to cancer cells and not to other parts of the body where they can cause side effects."

"DNA origami nanostructures have a lot of potential for drug delivery, not just for making effective drug delivery vehicles, but enabling new ways to study drug delivery. For instance, we can vary the shape or mechanical stiffness of a structure very precisely and see how that affects entry into cells," said Castro, director of the Laboratory for Nanoengineering and Biodesign.

In tests, the researchers found that AML cells, which had previously shown resistance to daunorubicin, effectively absorbed drug molecules when they were hidden inside tiny rod-shaped capsules made of DNA. Under the microscope, the researchers tracked the capsules inside the cells with fluorescent tags.

Each capsule measures about 15 nanometers wide and 100 nanometers long--about 100 times smaller than the cancer cells it's designed to infiltrate. With four hollow, open-ended interior compartments, it looks less like a pill a human would swallow and more like an elongated cinder block.

Postdoctoral researcher Christopher Lucas said that the design maximizes the surface area available to carry the drug. "The way daunorubicin works is it tucks into the cancer cell's DNA and prevents it from replicating. So we designed a capsule structure that would have lots of accessible DNA base-pairs for it to tuck into. When the capsule breaks down, the drug molecules are freed to flood the cell."

Castro's team designed the capsules to be strong and stable, so that they wouldn't fully disintegrate and release the bulk of the drugs until it was too late for the cell to spit them back out.

And that's what they saw with a fluorescence microscope--the cells drew the capsules into the organelles that would normally digest them, if they were food. When the capsules broke down, the drugs flooded the cells and caused them to disintegrate. Most cells died within the first 15 hours after consuming the capsules.

This work is the first effort for the engineers in Castro's lab to develop a medical application for the DNA origami structures they have been building.

Though DNA is stereotypically called the "building blocks of life," engineers today use natural and synthetic DNA as literal building blocks for mechanical devices. Previously, the Ohio State engineers created tiny hinges and pistons of DNA.

As Castro pointed out, DNA is a polymer--albeit a naturally occurring one--and he and his colleagues shape it into tiny devices, tools or containers by exploiting the physical interactions of the bases that make up the polymer chain. They build chains from DNA sequences that will naturally attract and bind with one another in certain ways, so that long the long polymers automatically fold up, or "self-assemble," into useful shapes.

In the case of this DNA Trojan horse, the researchers used the genome of a common bacteriophage, a virus that infects bacteria, and synthetic strands that were designed to fold up the bacteriophage DNA. Although the folded-up shape performs a function, the DNA itself does not, explained Patrick Halley, an engineering graduate student who is doing this work to earn his master's degree.

"One of the hardest things to get across when you're introducing this technology to people is that the DNA capsule doesn't do anything except hold a shape. It's just a static, rigid structure that carries things. It doesn't encode any proteins or do anything else that we normally think of DNA as doing," Halley said.

In keeping with the idea of DNA origami manufacturing, Castro said he hopes to create a streamlined and economically viable process for building the capsules--and other shapes as well--as part of a modular drug delivery system.

Byrd said the technique should potentially work on most any form of drug-resistant cancer if further work shows it can be effectively translated to animal models, though he stopped short of suggesting that it would work against pathogens such as bacteria, where the mechanisms for drug resistance may be different.

###

Other co-authors on the paper included Emily McWilliams, Matthew Webber, Randy Patton, Comert Kural and David Lucas. Funding for the research came from start-up funds provided to Castro by the Department of Mechanical and Aerospace Engineering, the Leukemia and Lymphoma Society, the National Cancer Institute, the D. Warren Brown Foundation, Four Winds Foundation and the Harry T. Mangurian Jr. Foundation.

Contact: Carlos Castro, 614-292-2662; Castro.39@osu.edu

John Byrd, 614-293-8330; Byrd.96@osu.edu

Written by Pam Frost Gorder, 614-292-9475; Gorder.1@osu.edu

Pam Frost Gorder | EurekAlert!

Further reports about: DNA DNA origami Trojan horse cancer cells capsule drug-resistant drugs leukemia

More articles from Life Sciences:

nachricht Repairing damaged hearts with self-healing heart cells
22.08.2017 | National University Health System

nachricht Biochemical 'fingerprints' reveal diabetes progression
22.08.2017 | Umea University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Cholesterol-lowering drugs may fight infectious disease

22.08.2017 | Health and Medicine

Meter-sized single-crystal graphene growth becomes possible

22.08.2017 | Materials Sciences

Repairing damaged hearts with self-healing heart cells

22.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>