Articles

NANOTECHNOLOGY

Who Are You? Gold Nanorods Identify Metastatic Tumor Cells

National Cancer Institute

August 2007

Using a series of gold nanorods, each with its own characteristic optical signature, researchers at Purdue University have developed a method for rapidly assaying the cellular composition of breast tumors. This assay technique could provide oncologists with a more accurate assessment of the metastatic potential of an individual’s cancer.

One important finding to come out of cancer research laboratories over the past few years is that tumors comprise many types of cells and that only a small proportion—the cancer stem cells—are responsible for the unlimited growth potential of a malignant tumor. Based on these findings, researchers have since identified a variety of cell surface markers on different types of breast cancer cells that may be predictive of a tumor’s ability to metastasize.

Reporting its work in the journal Nano Letters, a team of investigators led by Joseph Irudayaraj, Ph.D., developed a new technique for making biocompatible gold nanorods of various sizes to which they could then attach antibodies. Gold nanorods interact with light to produce plasmons, a wave-like motion of electrons on the surface of the nanorods. Depending on the ratio of a nanorod’s length to its diameter, these plasmons trigger light emission at a specific frequency that is easily detected using surface plasmon resonance spectroscopy.

To each nanorod of a given length and diameter, the researchers attached an antibody that recognizes one specific cancer cell surface marker. The researchers also prepared a gold nanorod-antibody construct that recognizes a biomarker found on all cell surfaces to serve as an internal reference control that would enable them to calculate relative amounts of the various tumor markers on a given cancer cell.

Using a panel of three different antibody-labeled gold nanorods, the investigators were able to characterize breast tumors according to their cellular composition and correlate their findings to the metastatic potential of each given cell type. These results were validated using flow cytometry, the standard, but laborious, technique used to classify cells according to surface markers. The researchers note that they could have monitored as many as 15 different antibody-nanorod constructs simultaneously.

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This work is detailed in the paper “Identity profiling of cell surface markers by multiplex gold nanorod probes.”

Investigators from Indiana University School of Medicine and the Walther Cancer Institute also participated in this study. An abstract of this paper is available through PubMed.

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http://nano.cancer.gov/news_center/2007/july/nanotech_news_2007-07-23b.asp

© 2007 National Cancer Institute. All Rights Reserved.

NANOTECHNOLOGY

Nanomedicine promises more functions than a drug

By Mark Isaac Thyss
Garden of Healing®

La Jolla, California

The Burnham Institute for Medical Research at UC Santa Barbara (Burnham) has developed nanoparticles that seek out tumors and bind to their blood vessels, and then attract more nanoparticles to the tumor target.

Led by Erkki Ruoslahti, M.D., Ph.D., his team demonstrated that the homing nanoparticle could be used to deliver a “payload” of an imaging compound, and in the process act as a clotting agent, obstructing as much as 20% of the tumor blood vessels. These findings are pending publication in the Proceedings of the National Academy of Sciences.

The promise of nanomedicine is based on the fact that a particle can perform more functions than a drug.

“Having identified the principle of self-amplification, we are now optimizing the process, hoping to obtain a more complete shut-down of blood flow into the tumor to strangle it,” says Ruoslahti. “We are also in the process of adding a drug delivery function to the particles. These two approaches are synergistic; the more particles we bring into the tumor, the greater the obstruction of the blood flow and more of the drug is delivered into the tumor.”

This work was supported with funding from the National Institutes of Health.

Dr. Erkki Ruoslahti is Distinguished Professor and former President and CEO at Burnham. He recently founded the “Vascular Mapping Center” at Burnham-UC Santa Barbara, which aims at developing applications for vascular “zip codes, molecular signatures in blood and lymphatic vessels (”vasculature”) that are specific to individual tissues and disease sites.

Burnham-UCSB, was established in 2006 through a collaborative effort of the Burnham Institute for Medical Research, based in La Jolla, California, and the University of California at Santa Barbara.

© 2006 Garden of Healing®. All rights reserved.

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Burnham Institute for Medical Research is an independent non-profit research institution dedicated to advancing the frontiers of scientific knowledge in the life sciences and medicine, and providing the foundation for tomorrow’s innovative therapies. Established in 1976 in La Jolla, California, Burnham today employs over 750 people and ranks consistently among the world’s top 20 research institutes in independent surveys conducted by the Institute for Scientific Information.

For additional information about Burnham: http://www.burnham.org

NEWS IN BRIEF

THE INDEPENDENT LAB

Fast-Food Grilled Chicken Contains Dangerous Carcinogen

By Mark Isaac Thyss
Garden of Healing®

Today a Washington advocacy group, Physicians Committee for Responsible Medicine, filed a lawsuit asking that restaurant chains should warn California consumers that their grilled chicken products contain carcinogens.

Grilled chicken products from seven national restaurant chains tested positive for a dangerous carcinogenic compound called PhIP, prompting the PCRM to file suit under California’s Proposition 65 to compel the restaurants to warn unsuspecting consumers.

PCRM is suing McDonald’s, Burger King, Chick-fil-A, Chili’s, Applebee’s, Outback Steakhouse, and TGI Friday’s in The Superior Court of the State of California for the County of Los Angeles.

“Grilled chicken can cause cancer, and consumers deserve to know that this supposedly healthy product is actually just as bad for them as high-fat fried chicken,” says PCRM president Neal Barnard, M.D. “Even a grilled chicken salad increases the risk of breast cancer, prostate cancer, and other forms of this lethal disease.”

Physicians Committee for Responsible Medicine commissioned an independent laboratory to test grilled chicken products from California outlets of all seven chains.

PhIP was found in every grilled chicken sample from each restaurant where samples were collected. PhIP is one of a group of carcinogenic compounds called heterocyclic amines (HCAs) that are found in grilled meat.

In 2005, the federal government officially added HCAs to its list of carcinogens, and PhIP has been on the California governor’s list of chemicals known to cause cancer for more than a decade.

California has more stringent chemical disclosure laws than most other states. The lawsuit asks the restaurants to post warnings about what it calls the carcinogenic dangers of the grilled chicken on its menu.

© 2007 Garden of Healing®. All rights reserved.