Lamc2 As A Prognostic Marker That Promotes Metastasis Of Lung Adenocarcinoma Through Epithelial-Mensenchymal Transition (Emt)

11034 Background: Metastasis is the main cause of death in non-small cell lung cancer (NSCLC) patients. Genes responsible for NSCLC metastasis are unknown. LAMC2 is one of the 3 chains (α3, β3, γ2) of laminin 332, an important component of basement membranes, and LAMC2 involvement in metastasis is unclear. Methods: We have established a metastasis model in nude mice by repeated intracardiac injection of A549 lung adenocarcinoma cells. After 3-4 rounds of intracardiac injections, 100% metastasis penetrance was obtained. Microarray analysis was performed to identify genes differentially expressed between parental (A549P) and round-3 (A549R3) cells. In vitro migration/invasion and in vivo metastasis assays were performed in LAMC2-overexpressed A549P, LAMC2-knockdown A549R4, PC9, H358, and H322 cells. Public RNA microarray data of human NSCLC (GSE8894, GSE3141; n=249) and LAMC2 immunohistochemistry (IHC) of stage I NSCLC TMA samples (n=250) were analyzed to correlate LAMC2 and prognosis. Results: We identified LAMC2 as a putative metastasis marker of NSCLC through gene expression profiling of A549 cells enriched for metastasis in mice. Ectopic LAMC2 expression increased migration/invasion, whereas LAMC2 knockdown decreased migration/invasion in vitro. Conditioned media containing secreted LAMC2 promoted cell migration/invasion, which were blocked by LAMC2 knockdown or LAMC2 neutralizing antibody. Ectopic LAMC2 expression induced mesenchymal but decreased epithelial markers, indicating EMT, whereas LAMC2 knockdown elicited the opposite. A549R4 LAMC2 knockdown cells showed less metastatic activity than A549R4shRNA control cells in mice. In public microarray data high LAMC2 mRNA predicted high risk of recurrence (GSE8894, P=0.022; GSE3141, P=0.029) in adenocarcinoma (AC) but not squamous carcinoma (SC). Our IHC study showed that high LAMC2 predicted high risk of recurrence (hazard ratio =1.8; P=0.040) and death (hazard ratio=1.9; P=0.028) in AC but not SC by multivariate analysis. Conclusions: LAMC2 promotes metastasis through activation of EMT pathways, and is a potential prognostic marker and therapeutic target of metastasis in lung adenocarcinoma.