Gold nanoparticles adsorbed less protein and were significantly smaller in solutions containing human tissue samples from prostate cancers than in solutions laced with human tissue samples from prostates that were normal or exhibited benign prostatic hyperplasia.

Smaller nanoparticles indicate more aggressive tumors

Prostate cancer ranks second as a cause of cancer death among men in the United States. But overtreatment of slow-growing tumors is a major problem; pathology reveals that 30% of cancers removed by radical prostatectomy did not require such invasive treatment.

A new nanoparticle-based assay developed by Qun Huo, PhD, an associate professor of nanomaterials chemistry at the University of Central Florida, and colleagues at the Florida Hospital Cancer Institute (both in Orlando) may help doctors grade prostate tumors more precisely.

In a study published in the Journal of Translational Medicine, the researchers showed that gold nanoparticles adsorbed less protein and were significantly smaller in solutions containing human tissue lysates from patients with prostate cancers than those laced with tissue from healthy and benign prostates.

The assay is straightforward. Immunoglobulin G (IgG) adsorbs to gold nanoparticles protected with citrate, forming a “protein corona.” Based on work they published last year in the Journal of Nanobiotechnology, Huo and her collaborators suspected that solutions with proteins released by malignant prostate tumors would interact with IgG and result in smaller particles than solutions with proteins released by nontumorigenic prostate samples, as detected by a dynamic light scattering technique. This turned out to be the case when they spiked an IgG solution with tissue lysates from commercially available samples from patients with normal prostate tissue, benign prostatic hyperplasia, or prostate cancer.

In fact, assays on tumors with higher Gleason scores usually showed smaller nanoparticles than those from tumors with lower scores. Huo hopes this indicates the assay eventually will allow doctors to grade the aggressiveness of a tumor quantitatively rather than subjectively.

Huo and her collaborators are planning a large clinical study with serum and tissue samples obtained using standard needle biopsies to verify their findings and determine how well nanoparticle size in the assay correlates to patients' disease courses. Huo is founder and president of Nano Discovery in Orlando, a company that has commercialized the dynamic light scattering technology used in the assay.