INTRODUCTION: The functions of large noncoding RNAs (ncRNAs) have remained 
elusive in many cases. Metastasis-Associated-in-Lung-Adenocarcinoma-Transcript-1 
(MALAT-1) is an ncRNA that is highly expressed in several tumor types.
METHODS: Overexpression and RNA interference (RNAi) approaches were used for the 
analysis of the biological functions of MALAT-1 RNA. Tumor growth was studied in 
nude mice. For prognostic analysis, MALAT-1 RNA was detected on 
paraffin-embedded non-small cell lung cancer (NSCLC) tissue probes (n = 352) 
using in situ hybridization.
RESULTS: MALAT-1 was highly expressed in several human NSCLC cell lines. MALAT-1 
expression was regulated by an endogenous negative feedback loop. In A549 
NSCLCs, RNAi-mediated suppression of MALAT-1 RNA suppressed migration and 
clonogenic growth. Forced expression of MALAT-1 in NIH 3T3 cells significantly 
increased migration. Upon injection into nude mice, NSCLC xenografts with 
decreased MALAT-1 expression were impaired in tumor formation and growth. In 
situ hybridization on paraffin-embedded lung cancer tissue probes revealed that 
high MALAT-1 RNA expression in squamous cell carcinoma of the lung was 
associated with a poor prognosis. On genetic level, MALAT-1 displays the 
strongest association with genes involved in cancer like cellular growth, 
movement, proliferation, signaling, and immune regulation.
CONCLUSIONS: These data indicate that MALAT-1 expression levels are associated 
with patient survival and identify tumor-promoting functions of MALAT-1.