Dysregulation of
cyclin D2 contributes to the pathogenesis of
multiple myeloma, and can occur through translocations that activate MAF/MAFB or MMSET/FGFR3. However,
cyclin D2 induction can also be seen in the absence of such translocations, such as in patients with hyperdiploid disease, through unknown mechanisms. In UniGene cluster data-mining and ECgene analysis, we found that zinc-finger with KRAB and SCAN domains 3 (ZKSCAN3), a novel
transcription factor, is overrepresented in this
malignancy, and three consensus ZKSCAN3 binding sites were found in the
cyclin D2 promoter. Analysis of a panel of myeloma cell lines, primary patient samples and datasets from Oncomine and the
Multiple Myeloma Genomics Portal (
MMGP) revealed expression of ZKSCAN3
messenger RNA (
mRNA) in a majority of samples. Studies of cell lines by western blotting, and of primary tissue microarrays by immunohistochemistry, showed ZKSCAN3
protein expression in a majority, and in a manner that paralleled messenger levels in cell lines. ZKSCAN3 overexpression was associated with increased gene copy number or genomic
DNA gain/amplification in a subset based on analysis of data from the
MMGP, and from fluorescence in situ hybridization studies of cell lines and primary samples. Overexpression of ZKSCAN3 induced
cyclin D2 promoter activity in a MAF/MAFB-independent manner, and to an extent that was influenced by the number of consensus ZKSCAN3 binding sites. Moreover, ZKSCAN3
protein expression correlated with
cyclin D2 levels in cell lines and primary samples, and its overexpression induced
cyclin D2. Conversely, ZKSCAN3 suppression using small hairpin RNAs (shRNAs) reduced
cyclin D2 levels, and, importantly, inhibited myeloma cell line proliferation. Finally, ZKSCAN3 was noted to specifically bind to
oligonucleotides representing sequences from the
cyclin D2 promoter, and to the endogenous promoter itself in myeloma cells. Taken together, the data support the conclusion that ZKSCAN3 induction represents a mechanism by which myeloma cells can induce
cyclin D2 dysregulation, and contribute to disease pathogenesis.