Expanding knowledge of pathways and proteins involved in oncogenesis has led to the development of targeted molecular therapeutics, including the use of small nucleic acid constructs designed to act as transcription factor decoys. Despite the plethora of small nucleic acid-based therapeutics of potential clinical value, no available method is capable of targeted, safe, minimally invasive, and repeated delivery of therapeutic quantities of these agents to cancers. As a result, clinical translation of small nuclec acid-based therapeutics has been slow. Accordingly, in this proposal, a unique multi-disciplinary team embodying expertise in chemical and biomedical engineering, acoustic physics, basic and clinical oncology, molecular biology, and imaging, will develop a new approach for targeted delivery of transcription factor decoys that capitalizes on unique bioeffects ensuing from ultrasound-induced vibrations of microbubbles (MBs). These bioeffects include enhanced cell membrane permeability to macromolecules, such as transcription factor decoys, which can be loaded on MBs and released solely at the target site upon induction of MB rupture by an ultrasound beam directed at the site. Because ultrasound also confers imaging capability, the project team will innovate a theranostic ultrasound- MB delivery system that combines ultrasound imaging with nucleic acid carrying capacity, which together may overcome current barriers to therapeutic transcription factor decoy delivery, while allowing real time visualization of the tumor and distribution of the decoy. We will test the overall hypothesis that MB can be loaded with a therapeutic nucleic acid (transcription factor decoy), that ultrasound-mediated delivery of the therapeutic will cause oncogene silencing and reduce tumor growth, and that the use of tumor-specific targeting moieties will enhance the therapeutic effect and simultaneously allow specific tumor detection. We will utilize the STAT3 decoy as a test therapeutic, as this small nucleic acid is known to have therapeutic potential and safety in animal cancer models. First, we will expose cultured carcinoma cells to STAT3 decoy- loaded MBs under varying ultrasound conditions, assay the resulting expression of downstream target genes, and determine the ultrasound and MB features which are critical for successful delivery of this particular agent. Then, to determine if the ultrasound-MB delivery platform induces STAT3 signal silencing and tumor growth suppression in vivo, we will intravenously deliver STAT3 decoy-loaded MBs and administer ultrasound to mice bearing squamous cell carcinomas, assay expression of STAT responsive genes, and ultrasonically track tumor growth over time. These studies will culminate in an efficient, non-invasive, targeted transcription factor decoy delivery strategy that should facilitate clinical implementation. Importantly, while our proposed delivery strategy targets a specific oncogene in this project, this work will establish general principles fr an image- guided ultrasound-MB therapeutic delivery platform that can be extended to other diseases for which small nucleic acid delivery represents a therapeutic approach.
Clinical adoption of molecular therapeutics for targeted silencing of abnormal genes involved in diseases such as cancer, including the use of small nucleic acid constructs designed to act as transcription factor decoys, is limited by the lack of strategies for targeted, safe, minimally invasive, and repeated delivery of these constructs. In this proposal, a unique multi-disciplinary team will develop a bedside ultrasound-microbubble diagnostic and delivery system that combines real time ultrasound imaging with transcription factor decoy-loaded microbubbles for ultrasound-induced decoy delivery specifically to tumors. The delivery platform developed in this project should facilitate the clinical translation of approaches using transcription factor decoys for treatment of cancer, ultimately leading to better outcome in patients afflicted with cancer. This platform can also be applied to molecular therapy of other diseases for which targeted gene silencing represents a treatment option.
