Abstract 2255: Mechanisms governing lung adenocarcinoma metastasis

Lung cancer is the leading cause of cancer deaths in men and women in the United States. Most lung cancer patients are diagnosed at a stage when they already have inoperable metastases. Identifying the drivers of lung cancer metastatic potential and the underlying mechanisms by which this state is induced, reversed or maintained is a question of immense clinical importance. Understanding the metastatic process in humans is limited, as early tumors exist in undiagnosed patients. Genetically engineered mouse models of lung adenocarcinoma provide an opportunity to study lung tumor progression and metastasis in vivo. We have recently improved upon existing lung adenocarcinoma mouse models enabling us to alter genes in developing tumors in vivo using lentiviral vectors that co-deliver Cre-recombinase and a cDNA. Additionally, the introduction of a tdTomato Cre reporter allows us to identify and isolate cells from all stages of cancer progression including primary tumors, disseminating tumor cells, circulating tumor cells, and micro-and macro-metastases. We hypothesize that differential gene expression between primary tumors and their metastases will identify key determinants of lung cancer metastatic progression. To this end, we have used RNA-Seq to identify differentially expressed genes between tumors and their metastases and validated a subset of these genes by Fluidigm® microfluidics qPCR. Our validated genes include the lysyl hydroxylase Plod2 (a collagen modifier) and the transcription factor Arntl2, both recapitulating gene expression correlations observed in human metastatic lung adenocarcinoma. Our data demonstrate that knockdown of Plod2 decreases the metastatic properties of mouse metastatic cell lines, specifically migration and the ability to give rise to metastases in transplantation assays. Migration and colony morphology defects upon knockdown of Plod2 could be rescued by the addition of normal collagen. Further in vitro experiments using soft agar assays demonstrated that an additional candidate gene, the transcription factor Arntl2, is required for anchorage independent growth of mouse metastatic cell lines. These findings were extended to in vivo transplant experiments, demonstrating that Arntl2 is critical for metastatic seeding. This in vivo phenotype was rescued by expression of a hairpin insensitive Arntl2 cDNA, demonstrating the specific role of Arntl2 in metastatic progression. Current efforts are focused on confirming the role of Arntl2 in human lung adenocarcinoma and determining the molecular mechanism of how Arntl2 modulates cancer progression and metastasis using RNA-Seq. Together, these studies will increase our knowledge of factors that mediate human lung adenocarcinoma progression with the potential to identify new targets for intervention at distinct steps of the metastatic cascade. Citation Format: Jennifer J. Brady, Chen-Hua Chuang, Deborah R. Caswell, Monte M. Winslow. Mechanisms governing lung adenocarcinoma metastasis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2255. doi:10.1158/1538-7445.AM2015-2255