(156g) Elastin Based Nano-Particles for Targeted Therapy of Lung Adenocarcinomas

Introduction: Nanoparticles have become increasingly popular for disease treatment in the last decade. Their ability to be used as transport and delivery vehicles for drugs has made their synthesis very appealing. In this work, we propose the development of nanoparticles for targeting of lung adenocarcinomas; this type of cancer represents about 40% of all lung cancers. Our nanoparticles consist of chimeric fusion proteins comprising of recombinant keratinocyte growth factor (KGF) and elastin like peptides (ELP). KGF is the ligand for the keratinocyte growth factor receptor (KGFR); which is highly expressed in lung adenocarcinoma. This chimeric fusion retains the bioactivity of KGF and the characteristic inverse phase transitioning behavior of ELPs. The phase transition behavior of ELPs induces nanoparticle self-assembly with the hydrophobic ELPs forming the core and hydrophilic KGF displayed at the periphery. The size of the nanoparticles is a direct function of the unique ELP sequences chosen.

Materials and Methods: The chimeric fusion protein (KGF-ELP) was produced recombinantly in bacteria. The formed nanoparticles were characterized using dynamic light scattering and transmission electron microscopy. RT-PCR and western blots were used for quantifying the expression of the KGFR in different lung adenocarcinoma cells and fibroblasts (Fb). Lung adenocarcinoma cells or fibroblasts (500,000 / well) were serum starved overnight and then treated with Cy3 labeled KGF-ELP (0.5ug/ml). Twenty-four hours after treatment, the cells were analyzed by flow cytometry. The fluorescence geometric mean was calculated using FACSDiva version 6.1.3 software.

Results and Discussion: The KGF-ELP fusion protein self-assembled into nanoparticles with diameters ranging from 100-500 nm depending on the length of the chosen ELP cassette. The particles were fairly mono-dispersed and were stable over a range of temperatures. The particle internalization per cell was further quantified using flowcytometery for different lung cancer cell lines, which yielded significantly high particle internalization compared to fibroblasts.

Conclusions: Our results indicate specific targeting of the nanoparticles to lung cancer cells via the KGF receptor. The particles were selectively internalized by KGFR expressing lung cancer cells through receptor mediated internalization, while very little internalization was seen in fibroblasts that do not express KGFR. Therefore these nanoparticles represent a promising approach for developing targeted therapies and imaging modalities for lung adenocarcinoma. Moreover, the recombinant method of producing the chimeric fusion proteins enables one to include different targeting motifs in the nanoparticle with relative ease; thereby making this strategy extremely versatile for different applications in cancer and medicine.