Application of nanotechnology for enhanced early detection of prostate cancer in African-American men: Abstract 4741

Once limited to the electronics industry, semiconductor material may hold the key to improving the detection of prostate cancer among African-American men. Nanotechnology using quantum dots made from semiconductor material allowed researchers to detect the presence of six biomarkers associated with prostate cancer.
If proven in clinical studies, the nanotechnology will enable physicians to diagnose prostate cancer at earlier stages, which is particularly important for African-American men.
“African-American men appear to have the highest rate of prostate cancer incidence in the world,” said Catherine M. Phelan, M.D., Ph.D., an assistant professor in cancer prevention and control at H. Lee Moffitt Cancer Center & Research Institute in Tampa, Fla. “ In addition, their prostate cancer mortality rate is twice as high as the rate for white Americans.”
Early detection is crucial. Among African-American men diagnosed with early stage prostate cancer, five-year survival rates are almost 100 percent. For men diagnosed with more advanced disease, five-year survival rates are 29 percent, according to Phelan.
To improve early detection, Phelan and her colleagues investigated quantum dot antibody conjugates. Quantum dots (QD) measure 5-20 nanometers in diameter. For comparison, a human hair measures 100,000 nm in diameter. The small size of the QDs results in new optical properties that allow observers to determine the size and energy of the QD and where it will emit light along the color spectrum.
“Smaller QDs are higher energy and emit in the blue part of the spectrum, whereas the larger-sized but lower-energy QDs emit light in the red part of the spectrum,” Phelan explained.
“If you want to look at a particular known protein in the blood, such as prostate specific antigen (PSA), you can attach the specific antibody for that protein to the QD and, using a laser, observe where the emission peak lies in the color spectrum. The height of the peak represents the amount of protein in the blood sample,” she said.
Phelan and her colleagues targeted established prostate cancer biomarkers: PSA, kallikrein 2 (KLK2), kallikrein 14 (KLK14), osteoprotegerin (OPG), antip53Ab, caveolin-1 (Cav-1) and interleukin-6 (IL-6). Using an African-American prostate cancer case-control collection, the researchers observed that the bioconjugated QDs displayed a spectral shift of the maximum position on average by 4 nm in comparison with nonconjugated QDs.
“The benefit of the observation may lie in the fact that the shift is different for each antibody, thus will show a peak at different wavelengths,” the researchers reported.
Phelan said there are two main advantages to QD technology over current methods, such as measuring PSA. First, the optical properties of QDs allow protein detection at lower levels when the tumor is in its earliest stages. Second, the technology offers the ability to detect multiple biomarkers, which will be more effective than a single biomarker.
“The technology can be used for detection of any cancer in any ethnic group,” Phelan said. The biomarkers in the study are unique to African-American men with prostate cancer, but the baseline levels of the proteins may differ among ethnic groups.
The technology could also be used to detect risk of recurrence, although the biomarkers may be different than for early detection, she said.