Lung cancer is the number one cancer killer, and metastasis is the main cause of high mortality in lung cancer patients. However, mechanisms underlying the development of lung cancer metastasis remain unknown. Using genome-wide transcriptional analysis in an experimental metastasis model, we identified laminin γ2 (LAMC2), an epithelial basement membrane protein, to be significantly upregulated in lung adenocarcinoma metastatic cells. Elevated LAMC2 increased traction force, migration, and invasion of lung adenocarcinoma cells accompanied by the induction of epithelial-mesenchymal transition (EMT). LAMC2 knockdown decreased traction force, migration, and invasion accompanied by EMT reduction in vitro, and attenuated metastasis in mice. LAMC2 promoted migration and invasion via EMT that was integrin β1-and ZEB1-dependent. High LAMC2 was significantly correlated with the mesenchymal marker vimentin expression in lung adenocarcinomas, and with higher risk of recurrence or death in patients with lung adenocarcinoma. We suggest that LAMC2 promotes metastasis in lung adenocarcinoma via EMT and may be a potential therapeutic target. Cell Death and Differentiation (2015) 22, 1341-1352; doi:10.1038/cdd.2014.228; published online 16 January 2015Lung cancer is the leading cause of cancer-related death. 1 Non-small-cell lung cancer (NSCLC) accounts for~80-85% of lung cancers. 2 Only 20-30% of NSCLC are radically resectable and the majority of lung cancer patients succumb to the disease. The high mortality of NSCLC is largely attributable to late diagnosis, when metastases are present. 2 The molecular mechanisms governing metastasis of NSCLC remain poorly understood.Metastasis is a complex, multistep process, involving migration and invasion of malignant cells from the primary tumor to blood vessels, intravasation, and survival in the circulation, and ultimately extravasation, colonization, and formation of secondary tumor at distant target organs. 3 Each of these events is classically driven by the acquisition of genetic and/or epigenetic traits in tumor cells and the cooperation of nonneoplastic stromal cells. Increased or decreased expression of several genes in tumors has been found to be correlated with metastasis. 3 However, specific gene alterations that drive NSCLC metastasis remain largely elusive.Laminin γ2 (LAMC2) is a subunit of the heterotrimeric glycoprotein laminin-332 (LAM-332, formerly laminin-5), consisting of the α3, β3, and γ2 chains. Although LAMC2 is an important structural component of the epithelial basement membrane (BM) in various normal tissues, 4 there is an emerging evidence for a pathological role of LAMC2 monomer in cancer. It has been demonstrated that LAMC2 protein expression correlates with clinical outcome of stage I lung adenocarcinoma (ADC) patients. 5,6 In addition, noncontinuous expression pattern of LAMC2 predicts the prognosis of esophageal squamous cell carcinoma (SCC), 7 and secreted LAMC2 in the serum is associated with the aggressiveness of pancreatic cancer. 8 Besides, LAMC2 monom...