Abstract P3-16-02: Nanotheranostics using plasmonic gold nanostars to target inflammatory breast cancer cells and tumor emboli
Authors: Shammas RL , Fales AM , Crawford BM , Hollenbeck ST , Vo-Dinh T , Devi GR 
Published: March 2017

Introduction: Due to the aggressive nature of inflammatory breast cancer (IBC) and insensitive imaging techniques, patients diagnosed with IBC have a poor prognosis. IBC's unique ability to form emboli leads to rapid growth and distant invasion. New therapies aimed at disrupting the formation of tumor emboli are needed. Gold nanostars (GNS) are unique nanoparticles that can be imaged in real time with high sensitivity, and are rapidly endocytosed into cancer cells. Due to their sharp spikes, GNS exhibit plasmonic properties, which strongly enhance the electromagnetic field upon laser excitation. In addition to their use as highly intense and stable fluorescent labels, these nanoparticles can be photothermally activated to trigger cellular ablation. The use of GNS as an imaging and therapeutic modality for IBC should be investigated.

Methods: IBC (SUM-149/SUM190), non-IBC (BT474M1/MD-MBA-231), and drug resistant isotype variant (rSUM-149) cell lines were incubated with GNS, stained with Hoechst33342, and imaged with multiphoton microscopy (MPM). The dose and time dependent effects of GNS on SUM-149 proliferation was assessed with MTT assays. Photothermal treatment was performed on GNS-labeled IBC, non-IBC, and drug resistant cancer cell lines. The effects of photothermal therapy on cell viability were assessed using fluorescein diacetate and propidium iodide. Using a tumor emboli model, SUM-149, rSUM-149, and SUM-190 tumor emboli were labeled with GNS on the 3rd day of embolic maturation. Emboli were sectioned, stained with H/E, and imaged with MPM to demonstrate the depth of GNS penetrance. The potential for photothermal ablation of the GNS-labeled tumor emboli was assessed using various laser intensities. Propidium iodide was used to examine emboli viability following treatment.

Results: In all cell lines, GNS displayed rapid cellular uptake without nuclear involvement. MTT assay showed that GNS concentrations of 0.15 and 0.20 nM caused decreases in cell proliferation at 6 and 12 hours. Proliferative capacity was unaltered at 24 hours for all concentrations, however this may be due to spectrophotometric interference with high intracellular GNS concentrations. Live/dead staining confirmed effective photothermal treatment in all cultures with a clear zone of cellular death. For tumor emboli studies, GNS allowed bright fluorescent monitoring of tumor emboli using MPM, and cross sectional imaging demonstrated GNS penetrance into the embolic core. Photothermal ablation of GNS-labeled tumor emboli was successfully demonstrated following laser irradiation. Cell death was confirmed with propidium iodide.

Conclusion: Gold nanostars provide a highly fluorescent intracellular label for cancer cell lines, and tumor emboli without significantly altering cell proliferation. Furthermore, the inherent optical properties of the GNS allows for a combined therapeutic application following phototoactivation. This is the first study to demonstrate the nanothernostic application of GNS in IBC tumor emboli. Prior studies have shown the effectiveness of photothermal ablation in in vivo sarcoma models; we are currently extending our studies to an IBC mouse model.

Supported by the P30 Cancer Center Support Grant (GRD) and Duke Exploratory Funds (TVD).

Citation Format: Shammas RL, Fales AM, Crawford BM, Hollenbeck ST, Vo-Dinh T, Devi GR. Nanotheranostics using plasmonic gold nanostars to target inflammatory breast cancer cells and tumor emboli [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-16-02.