Abstract B230: Targeting mitochondria for metastatic lung adenocarcinoma specific lethality.

Abstract

Abstract Introduction: Lung cancer is the leading cause of cancer deaths in the United States. Its ability to leave the primary tumor and establish inoperable metastasis impairs successful therapy and is a major contributor to its lethality. A genetically engineered mouse model recapitulates the human disease very well, incorporating conditional alleles of the Kras oncogene and p53 tumor suppressor. Recently, cell lines generated from non-metastatic primary lung tumors (TnonMet) and metastases (Met) in this model were shown to maintain their metastatic state and exhibit dramatic differences in gene expression programs. This unique set of cell lines from early stage non-metastatic tumors and late-stage metastases provides an opportunity to understand whether cancer progression also creates unique vulnerabilities. Experimental design: A pooled lentiviral-shRNA library screen which targeted ∼20,000 genes with >92,000 shRNA in two TnonMet and two Met cell lines was used to systematically uncover genes that are specifically required to sustain metastasis survival or growth. High-throughput sequencing of the shRNA in the cancer cell populations before and after 20 population doublings in culture identified shRNAs that disadvantaged each cell line. Gene-set enrichment algorithm was utilized to analyse the data. qRT-PCR, cell competition assays and mitochondria-specific dyes were used to verify the results and unravel the underlying mechanism. Results and Conclusion: The analysis of our pooled shRNA screen revealed mitochondrial ribosomal protein (Mrp) complexes as the top two gene-sets; in fact individual shRNA targeting more than 15 Mrp genes selectively disadvantaging Met cells with minimal impact on TnonMet cells. These results were individually verified with qRT-PCR. Interestingly, Met cells showed increased expression of mitochondria encoded genes, pointing to a strong imbalance in mitochondrial homeostasis. Furthermore, mitochondria-targeted therapy blocking mitochondrial translation or replication significantly inhibited Met cell growth more than TnonMet cell growth. Taken together, these results point to mitochondria as a metastasis-specific therapeutic target in lung adenocarcinoma and need to be further investigated. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B230. Citation Format: Barbara M. Gruener, Chen-Hua Chuang, Ian Linde, Shin-Heng Chiou, Ben Readhead, Joel Dudley, John Doench, David Root, Monte M. Winslow. Targeting mitochondria for metastatic lung adenocarcinoma specific lethality. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B230.