The recent rapid expansion of genomic data greatly contributes to the understanding of disease development and progression. To translate these genetic discoveries into clinical applications, we need to develop therapeutic platforms that can specifically modulate the expression of disease-related genes in vivo. Small RNAs, such as microRNAs and siRNAs function in messenger RNA silencing and post-transcriptional regulation of gene expression. Given the challenge of targeting delivery of these small RNAs to specific cells and tissues in vivo, we developed a small RNA targeting delivery platform, comprising a miRNA/siRNA sequence and a cell surface receptor-targeting DNA aptamer (a chemical antibody). In addition, as unmodified RNA oligonucleotides usually have a very short half-life in circulation in vivo, we incorporated cholesterol conjugation and base modifications into the components. This newly designed delivery platform combines all the desired attributes of a small RNA targeting molecule by enabling the specific delivery of miRNA/siRNA into the desired cells by the targeting aptamers and increasing half-life by limiting nuclease degradation and renal excretion. Furthermore, these three components are assembled together by complementary base pairing of the RNA sequences, thus creating a highly versatile platform in which the therapeutic or targeting moieties can be changed to suit the intended purpose or target indication. Using this platform, we recently developed a miR-26a delivery therapeutic that targets cells expressing the receptor tyrosine kinase, c-Kit, which we called miR-26a chimera. The miR-26a chimera significantly attenuated the myelosuppressive adverse effect of chemotherapy by silencing a miR-26a target gene Bak1 (pro-apoptotic gene) in c-Kit+ hematopoietic progenitor cells in vivo. Furthermore, the miR-26a chimera remarkably inhibited tumor growth of c-Kit+ breast cancer by silencing a miR-26a target gene Ezh2 (oncogene) in xenograft models. Using this model, we will further establish the therapeutic potential of this targeting delivery platform through two specific aims: 1) we will design optimal treatment regimen for myeloprotection and evaluate the safety of miR-26a chimera using chemotherapy-treated mice, and 2) we will determine the anti-tumor effects of miR-26a chimera using chemotherapy-treated tumor xenograft mouse models, which will drive the decision regarding further development. Our proposed studies not only provide the proof of concept data to support formal preclinical development of a novel small RNA targeting delivery platform for patients with advanced breast cancer, but also support the potential of our platform in the development of novel therapeutics and research tools for a broad range of diseases.
Public Health Relevance Statement: Project narrative We will evaluate the therapeutic potential and safety of a novel small RNA targeting delivery platform using a breast cancer model in vivo. This platform addresses the limitations observed with current approaches, specifically delivering active oligonucleotides for RNA interference to desired cells/tissues with high efficiency, and combines all the requirements for therapeutic application into a single versatile modular platform. Our proposed studies not only provide the preclinical proof of concept data for therapeutic development of this platform for advanced breast cancer, but will also contribute to the development of novel therapeutics and research tools for a broad range of diseases.
Project Terms: Address; advanced breast cancer; Adverse effects; Affinity; Antibodies; antitumor effect; Apoptotic; aptamer; Aptamer Technology; Attenuated; BAK1 gene; base; Base Pairing; Binding; Blood; Blood Circulation; Breast Cancer Model; Cancer Remission; Cell Surface Receptors; cell type; Cells; Chemicals; chemotherapy; Chemotherapy-Oncologic Procedure; Chimera organism; Cholesterol; clinical application; Complementary RNA; Cytoplasm; Data; design; Development; Dimensions; Disease; Disease model; DNA; Dose; Drug Kinetics; Excretory function; EZH2 gene; Gene Expression Regulation; Gene Silencing; Genes; Genetic; genomic data; Growth; Half-Life; Hematopoietic stem cells; Human; Immune; improved; in vivo; in vivo Model; interest; Kidney; Link; malignant breast neoplasm; Malignant Neoplasms; Maximum Tolerated Dose; Measures; Mediating; Messenger RNA; MicroRNAs; Modeling; Modification; Molecular Conformation; mouse model; Mus; Myelosuppression; novel; novel strategies; novel therapeutics; nuclease; Oligonucleotides; Oncogenes; optimal treatments; Patients; Post-Transcriptional Regulation; pre-clinical; preclinical development; prevent; Proto-Oncogene Protein c-kit; Receptor Protein-Tyrosine Kinases; Regimen; RNA; RNA Interference; RNA Sequences; Safety; safety assessment; Small Interfering RNA; Small RNA; Specificity; targeted delivery; Therapeutic; Therapeutic Agents; therapeutic development; therapeutic evaluation; Therapeutic Human Experimentation; therapeutic target; Tissues; tool; Translating; Treatment Efficacy; treatment optimization; Treatment Protocols; tumor; tumor growth; tumor microenvironment; tumor xenograft; Tumor-Infiltrating Lymphocytes; uptake; Xenograft Model
