Gene expression profile of the whole Mediator complex in human osteosarcoma and normal osteoblasts.

Mediator complex (MED) is an essential multi-subunit component of the transcription apparatus and plays a key role in the transcription regulation of many genes involved in several diseases, including cancer. Recently, numerous MED subunits have been implicated in cancer development and metastasis, and specific alterations in their coding genes have been found to correlate with some malignancies. It is conceivable that a specific MED alteration pattern can characterize each cancer type. However, to date, no study has reported the complete picture of MED subunits in a specific tumor. Thus, the aim of this study was to investigate for the first time the gene expression profile of the whole MED complex in human osteosarcoma (OS). To this purpose, we have examined all the MED subunit genes in three OS cell lines compared to normal osteoblasts by real-time RT-PCR. Interestingly, our findings indicate that the expression of most of the MED genes is altered in OS. Moreover, a very high overexpression of MED20 and MED31 can be observed in all the analyzed OS cells, thus suggesting for the first time a potential role of these subunits in human malignancies. Overall, this study may open the way to other functional studies exploring the role of the whole complex in cancer development and progression. These findings may lead to the identification of novel biomarkers, which can be used also in combination with imaging techniques for early detection, and/or to develop novel targets for innovative therapeutic approaches.