New Insights into Long Non-Coding RNA MALAT1 in Cancer and Metastasis

Abstract

Metastasis-associated lung adenocarcinoma transcript 1 (<i>MALAT1</i>) is one of the most abundant, long non-coding RNAs (lncRNAs) in normal tissues. This lncRNA is highly conserved among mammalian species, and based on in vitro results, has been reported to regulate alternative pre-mRNA splicing and gene expression. However, <i>Malat1</i> knockout mice develop and grow normally, and do not show alterations in alternative splicing. While <i>MALAT1</i> was originally described as a prognostic marker of lung cancer metastasis, emerging evidence has linked this lncRNA to other cancers, such as breast cancer, prostate cancer, pancreatic cancer, glioma, and leukemia. The role described for <i>MALAT1</i> is dependent on the cancer types and the experimental model systems. Notably, different or opposite phenotypes resulting from different strategies for inactivating <i>MALAT1</i> have been observed, which led to distinct models for <i>MALAT1'</i>s functions and mechanisms of action in cancer and metastasis. In this review, we reflect on different experimental strategies used to study <i>MALAT1'</i>s functions, and discuss the current mechanistic models of this highly abundant and conserved lncRNA.