My lab will develop genetic models of liver and lung cancer using small RNA tools, such as RNAi-mediated silencing and CRISPR/Cas9-mediated genome editing. The CRISPR/Cas9 system allows us to quickly generate somatic loss-of-function mutations in tumor suppressor genes or gain-of-function mutations in oncogenes. Our approach presents a new avenue for rapid development of cancer models, functional genomics, and proof-of-concept targeted cancer therapy. My laboratory will engage in the following areas of research over the next few years:

Discover and correct liver cancer genes using CRISPR-mediated genome editing

Many candidate cancer genes are being discovered through cancer genome-sequencing efforts, and simple genetic methods are needed to validate candidate cancer genes in vivo. CRISPR/Cas genome-editing has been successfully used in many organisms, including mouse and human cells. We will use in vivo CRISPR/Cas-mediated genome editing tools to discover, validate, and correct liver cancer genes in the mouse. To identify potential liver cancer therapeutic targets, we will devise novel CRISPR strategies to delete candidate oncogenes and test the effect on liver cancer progression. Because our approach allows us to perform genetic tests without breeding mice, our approach will speed up cancer gene discovery and drug target validation for liver cancer.

Characterize response and resistance to KRAS inhibition using in vivo RNAi and genome editing

KRAS is mutated in >30% of lung cancer. While most studies in the literature use inducible Kras cDNA, conditional shRNA system allows knockdown of endogenous levels of Kras in vivo, offering a more physiologic model of Kras inhibition. We will model the response and resistance to Kras inhibition in mouse models using lentiviral-based tet-on shRNA in the lung. Our recent studies show that after long-term Kras inhibition by RNAi, Kras-driven tumors relapse and become Kras-independent. We will explore the molecular basis of resistance to Kras inhibition using gene expression profiling. To completely delete the oncogenic KRAS gene and compare the phenotype with RNAi-mediated knockdown, we plan to use CRISPR to generate floxed KRAS conditional knockout alleles in lung cancer cell lines. These small RNA-based experiments will generate in vivo and in vitro platforms to uncover important KRAS biology.

Investigate oncogenic and tumor suppressor miRNA networks in lung cancer

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate mRNA translation or stability. Delineating miRNA networks can identify new miRNAs and miRNA antagonists for lung cancer treatment. We will cross-compare human lung adenocarcinoma miRNA expression profiles and cancer genome copy number analyses from TCGA (the Cancer Genome Atlas) to identify candidate miRNAs that drive or suppress tumor formation. We will use tet-on miRNA expression system to conditionally express miRNA at various stages of tumor progression and study the impact on tumor growth in vivo. Together, these studies will unveil miRNA networks in cancer using genetic tools.