The Regulation of YY1 in Tumorigenesis and its Targeting Potential in Cancer Therapy

Yin Yang 1 (YY1) is a multifunctional protein and regulates various processes of development and differentiation. Increasing evidence indicates an essential role of YY1 in tumorigenesis. As a transcription factor, YY1 regulates the expression of numerous genes that are mostly involved in cancers. YY1 can either activate or repress the target genes, depending on the cofactors that it recruits. Importantly, most studies to date suggest a proliferative or oncogenic role of YY1 in cancer development. Meanwhile, overexpression of YY1 has been observed in different types of cancers and YY1 has been proposed as a potential prognostic marker of these cancers. A reasonable hypothesis is that upregulated YY1 leads to unbalanced expression of its target genes and in turn initiates or arguments tumorigenesis. Ample studies indicate that YY1 exerts broad regulation in various epigenetic events, especially histone acetylation and methylation. Since most cancers exhibit deregulated epigenetics, overexpressed YY1 may contribute to these aberrant epigenetic statuses in cancer cells. The epigenetic processes regulated by YY1 are reversible. Therefore, it is possible that targeting YY1 may adjust various deregulated epigenetic events in cancer cells, restore the normal epigenetic conditions and consequently block cancer development. This review summarizes cancer-related studies of YY1 and discusses the potential of YY1 as a target of cancer therapy.