New discoveries of mdig in the epigenetic regulation of cancers

Mineral dust-induced gene (mdig) encodes a member of the evolutionarily conserved JmjC family proteins that play fundamental roles in regulating chromatin-based processes as well as transcription of the genes in eukaryotic cells. This gene is also named as myc-induced nuclear antigen 53 (MINA), nucleolar protein 52 (NO52) and ribosomal oxygenase 2 (RIOX2). Increased expression of mdig had been noted in a number of human cancers, esp. lung cancer. Emerging evidence suggests that the oncogenic activity of mdig is most likely achieved through its regulation on the demethylation of histone proteins, despite it lacks the structural identities of the demethylases. Here, we discuss the latest discoveries on the characteristics of the mdig protein and its roles in a wide variety of normal and carcinogenic processes. We will also provide perspectives on how mdig is involved in the maintenance and differentiation of the embryonic stem cells, somatic stem cells and cancer stem cells.