Targeted nanoparticles deliver therapeutic DNA to cancer cells



In what has been termed a landmark new study, it is suggested that wearing masks and washing hands prevents the spread of flu-like symptoms. While this may seem to many to be a case of the blatantly obvious, the study is apparently a “first-of-its-kind” examination of the effectiveness of non-pharmaceutical interventions in controlling the spread

Full Post: Protect yourself from flu by wearing a mask and washing your hands

Given that cancer is a disease caused by gene mutations, cancer researchers have been striving to develop gene therapies aimed at correcting these mutations. However, these efforts have been hobbled by the difficulty in safely and efficiently delivering anticancer genes to tumors. Nanoparticles, however, may solve these delivery issues, and two recently published studies, using two different types of nanoparticles, lend credence to that hypothesis.

Miqin Zhang, Ph.D., PI of the Nanotechnology Platform for Pediatric Brain Cancer Imaging and Therapy project at the University of Washington in Seattle, led a group of researchers that developed a targeted polymer nanoparticle that efficiently delivered a model gene into two types of cancer cells. More importantly, the gene functions properly once it enters the targeted cells. In the second study, Mansoor Amiji, Ph.D., PI of the Nanotherapeutic Strategy for Multidrug Resistant Tumors Platform Partnership at Northeastern University, and doctoral student Padmaja Magadala, M.S., used gelatin-based nanoparticles and a different targeting agent to efficiently deliver the same model gene to human pancreatic tumor cells. As in the first study, the delivered gene functioned properly inside the tumor cells.

The nanoparticle developed by Dr. Zhang’s group was made of two polymers-polyethyleneimine (PEI) and polyethylene glycol (PEG)-linked to chlorotoxin, a small protein isolated from scorpion venom. Previous research by several research teams had shown that chlorotoxin binds many types of tumors, including gliomas and medulloblastomas, two types of brain cancer. PEI forms stable nanoparticles that bind deoxyribonucleic acid (DNA), but the resulting nanoparticles can be toxic. Adding PEG to the nanoparticles provides a biocompatible surface that greatly reduces the toxicity of PEI.

As a test, Dr. Zhang and her colleagues used these nanoparticles to deliver DNA that codes for green fluorescent protein (GFP), which is used widely to study gene expression. When added to tumor cells expressing the chlorotoxin receptor, the nanoparticles were quickly taken up by the cells. The cells also turned green, thanks to the expression of GFP. In contrast, nanoparticles lacking chlorotoxin were not taken up by the cells, and tumor cells lacking the chlorotoxin receptor did not take up the nanoparticles.

(The three scientists credited with discovering and developing GFP as a critical research tool were awarded the 2008 Nobel Prize in Chemistry. One of those scientists, Roger Tsien, Ph.D., is an investigator at NCI’s Center of Nanotechnology for Treatment, Understanding, and Monitoring of Cancer at the University of California, San Diego.)

Dr. Amiji’s approach differed, in that he used a peptide that targets the epidermal growth factor receptor that is overexpressed by several types of tumors, including pancreatic cancer. He also used a nanoparticle constructed from negatively charged gelatin, which readily incorporates DNA and other nucleic acids, which are positively charged at normal physiological pH. The structure of the nanoparticle material also promotes DNA to take on a supercoiled structure that is efficiently taken up and transported to the cell’s nucleus, a critical factor for gene expression to occur. To improve the biocompatibility of these nanoparticles, Dr. Amiji also used PEG to coat the nanoparticles.

When added to pancreatic cells, nearly half of the administered dose of these engineered, targeted nanoparticles were taken up by pancreatic tumor cells, a remarkably high value. More importantly, a large percentage of the transfected cells subsequently expressed GFP. In addition, the nanoparticles were not toxic to the cells, an important finding given that they did not contain any therapeutic agent.

The work from Dr. Zhang’s group, which was detailed in the paper “A ligand-mediated nanovector for targeted gene delivery and transfection in cancer cells,” was supported 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 Web site. View abstract

The study headed by Dr. Amiji, which was described in the paper “Epidermal growth factor receptor-targeted gelatin-based engineered nanocarriers for DNA delivery and transfection in human pancreatic cancer cells,” was also supported by the NCI Alliance for Nanotechnology in Cancer. An abstract of this paper is available at the journal’s Web site. View abstract

http://nano.cancer.gov

Link




Working with a nanoparticle designed to target and image glioblastoma, a form of brain cancer, investigators at the University of Washington in Seattle have found that these same nanoparticles inhibit tumor cell invasion, one of the key events that leads to the metastatic spread of cancer. The investigators have also determined how the nanoparticles exert

Full Post: Toxin-nanoparticle combo inhibits brain cancer invasion while imaging tumors



A research team from the Massachusetts Institute of Technology (MIT)-Harvard Center for Nanotechnology Excellence has custom-designed nanoparticles that can deliver the anticancer drug cisplatin specifically to prostate cancer cells. The nanoparticles are composed of two different polymers and are decorated with a nucleic acid aptamer that binds to the tumor marker prostate-specific membrane antigen.

Full Post: Targeted nanoparticles boost platinum-based anticancer therapy



Antibodies that target epidermal growth factor receptor (EGFR) have proven themselves as potent anticancer drugs. Now, a team of investigators led by Shuming Nie, Ph.D., and Lily Yang, Ph.D., both at the Emory University School of Medicine and members of the Emory-Georgia Tech Nanotechnology Center for Personalized and Predictive Oncology, is aiming to capitalize on

Full Post: Artificial antibody delivers nanoparticles to tumors



One of the hallmarks of many nanoparticle-based anticancer therapeutics and imaging agents is that they accumulate in tumors thanks to the fact that they are small enough to escape from the bloodstream through the leaky blood vessels that surround tumors. And although many if not most tumors are surrounded by leaky blood vessels, the

Full Post: Nanoparticle reports on drug delivery to breast tumors, predicts response to therapy



One of the problems that cancer patients face is that many of the most potent anticancer therapies can be administered only by injection, which means that cancer patients must travel to receive their medication. But thanks to a new type of nanoparticle developed by researchers at the Johns Hopkins University School of Medicine, future cancer

Full Post: Polymer nanoparticle for oral anticancer drug delivery