Cancer is a class of cellular diseases characterized by uncontrolled growth, invasion, and metastasis. Although cancer is multifaceted with complex underlying genetic determinants, emerging evidence points to common signatures at the level of intracellular signaling across different tissue and cancer types. A system capable of detecting combinations of these intracellular molecular signals in cells has significant potential for the diagnosis, prevention, treatment, and monitoring of the disease at a single-cell level. Recently, scientists have developed first generation genetic circuits and sensors that operate as information processing systems in cells. The proposed research will develop and study molecular biosensors engineered to detect and monitor endogenous microRNAs, a class of small, noncoding RNAs that regulate gene expression by targeting RNA transcripts. The objectives of the proposed research are to: (a) design and optimize molecular biosensors that respond with sensitivity and specificity to combinations of endogenous microRNAs, (b) develop monoclonal tumor cell lines with integrated biosensors based on the NCI-60 panel, and (c) study microRNAs and their relationship to disease by monitoring their expression through the cell cycle in response to drug treatment. Intellectual merit: MicroRNAs have emerged as important modulators in both development and disease, including cancer. Experimental evidence implicates aberrant microRNA expression profiles in most human malignancies. The ability to process microRNA information reliably (with single-cell resolution) will generate new tools for basic cancer research and lead to new cancer treatment modalities. Specifically, the application of the microRNA biosensors to tumor cell lines will dramatically advance our understanding of microRNA expression and dynamics in living cells. The development of monoclonal cell lines with the selected microRNA sensors will pave the way for a new class of tools for the study of microRNAs. This will be a major new direction that will spark a range of equivalent studies in other cell lines and with other microRNAs. Broader impact: The experiments will be performed in NCI-60 colon, hematologic, lung, and pancreatic tumor cell lines. The criteria for the selection of the particular cell lines was based: on the prevalence of lung cancer and colon cancer in the United States (the leading cause of cancer death for both men and women and the second leading cause of cancer deaths for both men and women combined, respectively); because pancreatic and hematologic cancers have very poor 5-year survival (pancreatic cancer in particular) underscoring the urgent need for new diagnostic and treatment tools. The collection of monoclonal cell lines harboring the biomolecular networks will be made available to the scientific community. The proposed research will also form an educational platform where students will be exposed to an integrated research environment, combining theory and experiments at the intersection of biology and engineering.