Using Nucleic Acid Aptamers to Modulate the Specificity, Binding, and Quantity of Drug to Create a Personalized Treatment Approach Towards Small Cell Lung Carcinoma
Ricky J. Whitener1, 2, 3, Katherine A. Windham1,2, Jacek Wower1, 3, Mark E. Byrne2, 3, 4
1 RNA Biochemistry Laboratories, Department of Animal and Dairy Sciences, College of Agriculture
2 Biomimetic & Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Chemical Engineering, Auburn University
3 US Dept of Education GAANN Graduate Fellowship Program in Biological & Pharmaceutical Engineering
4 Biomimetic & Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Biomedical Engineering, Rowan University
Lung cancer remains the most frequently diagnosed and deadliest cancer with 1.8 million new cases and 1/5th of all cancer deaths annually. Small cell lung carcinoma (SCLC), one of two subtypes of lung cancer, accounts for 15% - 20% of all lung cancer diagnoses. The survival rates for SCLC patients have not significantly improved over the last 40 years. Untreated SCLC is rapidly fatal within two to four months. In our studies, we use doxorubicin, one of the best drugs for treating SCLC. We constructed a novel high payload nanocarrier for doxorubicin. The release of the drug can be modulated to account for the genomic characteristics and health status of the patient. At present, we evaluate the effectiveness of our nanocarrier in vitro using cultured SCLC cells.
Our nanocarrier consists of a 15 nm gold nanoparticle (AuNp) detectable by x-rays, single-stranded DNA anchors covalently bound to the AuNp surface, and DNA aptamers. We used aptamers that are known to bind to the cultured SCLC cell line NCI-H69 and modified them by adding a drug-binding site that can accommodate 5-7 molecules of doxorubicin. Each aptamer is equipped with a single-stranded segment that is complementary to the single-stranded DNA anchor. Such design produces a drug nanocarrier that can be readily programmed with either one or several cancer-specific aptamers. By increasing the size of the AuNps, we can produce nanocarriers that carry more aptamers and deliver higher payloads of drug to the surface of the cancer cell. Alternatively, we can produce smaller nanocarriers that can be more readily taken up by cancer cells.
Presently, we are studying the cellular uptake of 15-nm nanocarriers using transmission electron microscopy (TEM), hyperspectral microscopy, and other techniques that allow for visualization of particles inside cells. In the cellular uptake tests, we are using the cultured SCLC cell line NCI-H69 that was used for the selection of SCLC-specific aptamers. For control experiments we are using cultured non-SCLC cells NCI-H661 that are not recognized by the aptamers attached to our nanocarrier. The TEM studies are complemented by cell viability and carrier/drug effectiveness tests (XTT Assay). Preliminary results indicate that by manipulating the size of the nanocarrier, the structure of the DNA aptamers, and its drug-binding segment, we have created a an effective yet flexible, versatile, highly tunable platform that is capable of recognizing a specific SCLC tumor, and is able to deliver controlled amounts of doxorubicin to individualized patients as dictated by their health status.