Glycogen synthase kinase 3 (GSK-3) and forkhead transcription factors (FH) are important downstream proteins in the PI3-kinase/AKT kinase signaling pathways which promote cell survival and regulate the cell cycle. Our studies provided the first evidence for a direct link between GSK-3 and FH transcription factors. In myeloma, FH transcription factors are inactivated due the effects of interleukin- 6 and we provide evidence for reactivation and induction of cell cycle arrest and apoptosis by inhibition of GSK-3. Our hypothesis is that both GSK-3 and FH transcription factors are critical in growth regulation of myeloma cells, Specific Aim 1 we will determine the role of GSK-3 in the regulation of myeloma cell growth. Studies will be performed to determine whether FH transcription factors are substrates of GSK-3 in vitro and vivo. Furthermore, we will identify GSK-3/FH regulated genes and their function in myeloma.
In Specific Aim 2 we will investigate the mechanisms of regulation of the transcriptional function of FH proteins in myeloma cells. Studies will be performed to determine the significance of FH and p300 co-factor interaction, map the sites of acetylation by p300 and identify novel co-factors that interact with FH transcription factors.
In Specific Aim 3 we will investigate the efficacy of GSK-3 inhibitors in suppressing myeloma cell growth. Two small molecule inhibitors of GSK-3 will be used to determine whether these compounds are effective in growth suppression and apoptosis of myeloma cells. Purified primary plasma cells will be used in our studies in addition to testing these agents in the SCID-hu myeloma mouse model. We will use biochemical, cellular and molecular biology approaches to address the questions outlined in each specific aim. Altogether, the studies proposed here will advance our understanding of how upstream signaling events merge with transcriptional networks in the cell nucleus to regulate gene transcription. Our studies not only will examine the mechanistic aspects of transcriptional regulation in the context of multiple myeloma, but also propose to test the efficacy of two small molecule drugs in controlling malignant cells growth. Therefore these studies have broad implications for understanding regulatory mechanisms in malignant transformation.
