American Lung Association: “Identifying Exploitable Biomarkers of Lung Cancer Metastasis”
Rationale. Most cancer deaths are caused by metastatic disease, and the prevention of metastasis is a significant focus of clinical research. Aberrant expression of miRNAs has been found in all cancers, yielding insights into disease processes that would be difficult to detect by other methods and revealing fundamental therapeutic vulnerabilities. miRNAs have been shown to be exported by tumor cells and stable in serum, potentially acting as vanguards of the metastatic process (1; 2) through their ability to modify the properties and behavior of other cells. miRNAs are therefore potential biomarkers of metastasis and therapeutic targets by which metastasis may be controlled. There is currently no method by which to distinguish miRNAs that originate from tumor cells from those that are involved in host responses, such as a general inflammatory response, limiting our ability to exploit their value. The current proposal addresses this knowledge gap.
Specific Aims and Hypotheses. Our hypothesis is that a recently-developed RNA tagging approach can be applied to isograft models based on cells that differ in their ability to metastasize, allowing us to (1) identify specific miRNAs in serum and tissue that are secreted by tumor cells or expressed by the host, and (2) explout those as therapeutic targets to control metastasis.
Overall experimental approach. Cell lines derived from metastatic and non-metastatic models of murine lung adenocarcinoma will be stably transfected to express the labeling enzyme and injected into syngeneic mice to induce tumor formation. The mice will be fed a diet supplemented with the enzyme-substrate. Since the tumor cells express the enzyme, they will synthesize tagged miRNAs, while host cells, which do not express the enzyme will not. Any miRNAs that the tumor releases into the blood or adjacent tissue will also be tagged. Separation of the miRNAs present in the tumor, normal adjacent tissue, and serum into labeled and unlabeled fractions followed by small RNA sequencing then enables the controlled comparison of the profile of miRNAs released into the blood specifically by the tumor relative to the profile of miRNAs from the host. We will use this approach to identify miRNA biomarkers of metastasis and to design therapeutic interventions based on reversing the changes in miRNA expression in the target cells.
Impact. Completion of the proposed work will identify miRNAs that are biomarkers of lung cancer metastasis that can then be investigated as therapeutic targets in the same mouse models, extended to models based on human cell lines, evaluated in patient populations, and developed as clinical tools. In addition, this work will generate a new set of resources for investigating questions about how cancer cells communicate over short and long distances and how the host organism responds, both locally and globally.