Effects of MMSET on gene expression in multiple myeloma

The MMSET (Multiple Myeloma SET domain) protein is overexpressed in multiple myeloma patients with the translocation t(4;14). Although studies have shown the involvement of MMSET/WHSC1 in development, its mode of action in the pathogenesis of multiple myeloma (MM) is largely unknown. We found that MMSET is a major regulator of chromatin structure and transcription in t(4;14) MM cells. High levels of MMSET correlate with an increase in lysine 36 methylation of histone H3 and a decrease in lysine 27 methylation across the genome, leading to a more open structural state of the chromatin. Loss of MMSET expression alters adhesion properties, suppresses growth and induces apoptosis in MM cells. Consequently, genes affected by high levels of MMSET are implicated in the p53 pathway, cell cycle regulation and integrin signaling. Regulation of many of these genes required functional histone methyl-transferase (HMT) activity of MMSET. These results implicate MMSET as a major epigenetic regulator in t(4;14)+ MM.

18

Martinez-Garcia E, Popovic R, Min DJ, Sweet SM, Thomas PM, Zamdborg L, Heffner A, Will C, Lamy L, Staudt LM, Levens DL, Kelleher NL, Licht JD