Mediator complex (MED) is an evolutionarily conserved multiprotein, fundamental for growth and survival of all cells. In eukaryotes, the
mRNA transcription is dependent on
RNA polymerase II that is associated to various molecules like
general transcription factors, MED subunits and
chromatin regulators. To date, transcriptional machinery dysfunction has been shown to elicit broad effects on cell proliferation, development, differentiation, and pathologic disease induction, including
cancer. Indeed, in malignant cells, the improper activation of specific genes is usually ascribed to aberrant transcription machinery. Here, we focus our attention on the correlation of MED subunits with
carcinogenesis. To date, many subunits are mutated or display altered expression in human
cancers. Particularly, the role of MED1, MED28, MED12, CDK8 and
Cyclin C in
cancer is well documented, although several studies have recently reported a possible association of other subunits with
malignancy. Definitely, a major comprehension of the involvement of the whole complex in
cancer may lead to the identification of MED subunits as novel diagnostic/prognostic tumour markers to be used in combination with imaging technique in clinical oncology, and to develop novel anti-
cancer targets for
molecular-targeted therapy.