Abstract B15: Cell motility and deformability in the pathogenesis of lung cancer.

The most effective therapy for lung cancer is surgical resection, but it recurs in approximately 50% of patients with early stage disease, with recurrence most commonly presenting as metastatic disease. This suggests that micrometastatic disease is often already present at the time of surgery, but below the level of detection of our current imaging studies. This is consistent with the reports of circulating tumor cells in patients with stage-I non-small cell lung cancer (NSCLC). Although metastatic behavior is often considered a late stage event, these clinical findings suggest that the metastatic process is also operative early in the pathogenesis of the disease. These clinical observations are also consistent with recent laboratory-based investigations indicating that dissemination may occur during early tumor development, particularly in the context of the genetic program associated with epithelial-mesenchymal transition (EMT). Our preliminary studies indicate that a key regulator of the EMT program, Snail, is responsible for both transformation and enhanced motility of human bronchial epithelial cells (HBECs). Cells that over-express Snail (HBEC-Snail) show structural features indicative of enhanced motility, including filopodia, lamellipodia, membrane ruffling, and front-rear polarity. HBEC-Snail cells move with up to 50% greater velocity than vector control cells. We find that HBECs expressing genes associated with EMT or bearing common NSCLC driver mutations (p53/KRAS), show marked heterogeneity in their capacity for cell motility. Greater than an order of magnitude difference between the fastest and slowest moving cells was consistently observed in these cells. We hypothesize that enhanced epithelial cell motility is operative during premalignancy and is a driver of early metastatic dissemination. The overarching objective of this research is to elucidate the fundamental mechanisms involved in epithelial cell motility and their potential impact on disease onset and progression by coupling novel in vitro and in vivo models of human lung carcinogenesis and an innovative motility-based cell isolation technique. As a result of isolating these fast moving cells, we have shown that the selected cells move through transwell membranes at a 45- to 120-fold increased frequency compared to their unselected counterparts. We have also found that cellular deformability relates to a motile phenotype. By using atomic force microscopy (AFM) and deformability cytometry (DC), we have determined that highly migratory HBEC-Snail cells are more deformable than unselected cells. In the future, we intend to implant selected cells into mice to determine if there is a physiologically-relevant transformation- or cancer-associated phenotype, such as decreased time to metastasis or increased final metastatic burden. These are the first investigations to tie the physical traits of cell motility and deformability to lung carcinogenesis and early metastatic behavior. We anticipate that further investigation, including transcriptome analysis of selected cells by RNAseq, will yield a more complete understanding of the molecular determinants of lung cancer pathogenesis, which will stimulate development of more effective chemoprevention and early detection, benefiting those at risk for lung cancer and those with early stage disease. These studies were supported by funding from the following: NIH/NCI #T32-CA009120-36 (SMD, PCP, SJP), NCI #U01CA152751 (SMD, TCW), NCI #U01CA152751-S1 (SMD, TCW, SJP), NCI #U01CA152751-AS (SMD, KK), NIH/NHLBI #T32HL072752 (SMD, EL), Department of Veteran Affairs #5I01BX000359 (SMD), University of California Tobacco-Related Disease Research Program (TRDRP) #22DT-0005 (PCP), TRDRP #18FT-0060 (TCW), and TRDRP #20KT-0055 (TCW), Lung Cancer SPORE #P50CA70907 (JDM, JEL), Packard Foundation Fellowship (DDC). Citation Format: Paul C. Pagano, Shivani Sharma, Sean O9Byrne, Henry T. Tse, Stacy J. Park, Elvira L. Liclican, Kostyantyn Krysan, Tonya C. Walser, Jill E. Larsen, John D. Minna, James K. Gimzewski, Dino Di Carlo, Steven M. Dubinett. Cell motility and deformability in the pathogenesis of lung cancer. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr B15.