Functions and regulatory mechanisms of metastasis-associated lung adenocarcinoma transcript 1

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long noncoding RNA whose transcript is around 8 kb in length. As an important stress response molecule, MALAT1 can be expressed differently under stress conditions, such as hypoxia, high glucose, hydrogen peroxide, ultraviolet irradiation, infection, and chemical stimulation. MALAT1 is involved in regulating multiple cell behaviors, such as proliferation, apoptosis, differentiation, migration, epithelial-mesenchymal transition, autophagy, and morphological maintenance. Extensive evidence show that MALAT1 plays critical roles in the physiopathological process of embryo implantation, angiogenesis, tissue inflammation, tumor progression, liver fibrosis, cardiovascular remodeling, and diabetes progression by regulating gene transcription, forming RNA-protein complexes with proteins as a structural component, regulating protein activity, assisting protein localization, mediating epigenetic changes, or by acting as a competing endogenous RNA. Furthermore, MALAT1 can affect the sensitivity of chemotherapy and radiotherapy; therefore, it could be used as a potential drug target for chemotherapy and radiotherapy sensitization. The levels of MALAT1 are reported to be overexpressed in most tumor tissues or sera, and the expression levels of MALAT1 often affect the tumor size, stage, lymph node metastasis, and distant invasion. Therefore, MALAT1 can be used as a biomarker for early diagnosis, severity assessment, or prognostic assessment. This review outlines the current understanding of the biological role and function of MALAT1. In the meantime, we have summarized the mechanisms involved in the reulation of MALAT1 expression and the mechanisms by which MALAT1 regulates the physiological and pathological processes.