Functional roles of non-coding RNAs regulated by thyroid hormones in liver cancer

Recent reports have shown the important role of the non-coding part of human genome RNA (ncRNA) in cancer formation and progression. Among several kinds of ncRNAs, microRNAs (miRNA) play a pivotal role in cancer biology. Accumulating researches have been focused on the importance of non-coding genes in various diseases. In addition to miRNAs, long non-coding RNAs (lncRNAs) have also been extensively documented. Recently, the study of human liver cancer has gradually shifted to these non-coding RNAs that were originally considered "junk". Notably, dysregulated ncRNAs maybe influence on cell proliferation, angiogenesis, anti-apoptosis, and metastasis. Thyroid hormones play critical roles in human development and abnormalities in thyroid hormone levels are associated with various diseases, such as liver cancer. Thyroid hormone receptors (TR) act as ligand-activated nuclear transcription factors to affect multiple functions through the gene-level regulation in the cells and several studies have revealed that thyroid hormone associated with ncRNAs expression. TR actions are complex and tissue- and time-specific, aberrant expression of the various TR isoforms have different effects and are associated with different types of tumor or stages of development. In this review, we discuss various aspects of the research on the thyroid hormones modulated ncRNAs to affect the functions of human liver cells.