MLL1 inhibition reduces IgM levels in Waldenström macroglobulinemia

GLI3 Is Required for M2 Macrophage Polarization and M2-Mediated Waldenström Macroglobulinemia Growth and Survival

Waldenstrom macroglobulinemia (WM) is a non-Hodgkin B-cell lymphoma, characterized by bone marrow infiltration with plasma cells and lymphocytes. The tumor microenvironment (TME) plays an important role in mediating WM cell biology, but the effects of macrophages on WM biology remains unclear. Here, we investigated the effects of macrophages on WM growth and survival and identified a novel role for transcription factor GLI3 in macrophage polarization. We found that co-culture of M0 and M2 macrophages promoted WM cell growth and survival, and co-culture WM cells with M0 macrophages induced M2-like phenotypes. Interestingly, GLI3 expression was induced in M2 macrophages (not M1), leading us to perform analysis of macrophages from mice lacking Gli3 in myeloid cells (M-Gli3-/- mice). A subset of differentially expressed genes implicated a role for GLI3 in macrophage polarization. Macrophages from M-Gli3-/- mice did not induce WM cell proliferation and reduced survival compared to M2 macrophages from WT mice. In addition, in vitro polarization of M0 macrophages from M-Gli3-/- was not able to induce M2 markers such as CD163, despite inducing iNos expression (M1 marker). Taken together, these results suggest a role for M2 macrophages in promoting WM cell growth and identify GLI3 as a modulator of macrophage polarization.

A novel mechanism of regulation of the oncogenic transcription factor GLI3 by toll-like receptor signaling

The transcription factor GLI3 is a member of the GLI family and has been shown to be regulated by canonical hedgehog (HH) signaling through smoothened (SMO). Little is known about SMO-independent regulation of GLI3. Here, we identify TLR signaling as a novel pathway regulating GLI3 expression. We show that GLI3 expression is induced by LPS/TLR4 in human monocyte cell lines and peripheral blood CD14+ cells. Further analysis identified TRIF, but not MyD88, signaling as the adapter used by TLR4 to regulate GLI3. Using pharmacological and genetic tools, we identified IRF3 as the transcription factor regulating GLI3 downstream of TRIF. Furthermore, using additional TLR ligands that signal through TRIF such as the TLR4 ligand, MPLA and the TLR3 ligand, Poly(I:C), we confirm the role of TRIF-IRF3 in the regulation of GLI3. We found that IRF3 directly binds to the GLI3 promoter region and this binding was increased upon stimulation of TRIF-IRF3 with Poly(I:C). Furthermore, using Irf3 -/- MEFs, we found that Poly(I:C) stimulation no longer induced GLI3 expression. Finally, using macrophages from mice lacking Gli3 expression in myeloid cells (M-Gli3-/- ), we found that in the absence of Gli3, LPS stimulated macrophages secrete less CCL2 and TNF-α compared with macrophages from wild-type (WT) mice. Taken together, these results identify a novel TLR-TRIF-IRF3 pathway that regulates the expression of GLI3 that regulates inflammatory cytokines and expands our understanding of the non-canonical signaling pathways involved in the regulation of GLI transcription factors.

Intracellular and Extracellular Antifreeze Protein Significantly Improves Mammalian Cell Cryopreservation

Cell cryopreservation is an essential part of the biotechnology, food, and health care industries. There is a need to develop more effective, less toxic cryoprotective agents (CPAs) and methods, especially for mammalian cells. We investigated the impact of an insect antifreeze protein from Anatolica polita (ApAFP752) on mammalian cell cryopreservation using the human embryonic kidney cell line HEK 293T. An enhanced green fluorescent protein (EGFP)-tagged antifreeze protein, EGFP-ApAFP752, was transfected into the cells and the GFP was used to determine the efficiency of transfection. AFP was assessed for its cryoprotective effects intra- and extracellularly and both simultaneously at different concentrations with and without dimethyl sulfoxide (DMSO) at different concentrations. Comparisons were made to DMSO or medium alone. Cells were cryopreserved at -196 °C for ≥4 weeks. Upon thawing, cellular viability was determined using trypan blue, cellular damage was assessed by lactate dehydrogenase (LDH) assay, and cellular metabolism was measured using a metabolic activity assay (MTS). The use of this AFP significantly improved cryopreserved cell survival when used with DMSO intracellularly. Extracellular AFP also significantly improved cell survival when included in the DMSO freezing medium. Intra- and extracellular AFP used together demonstrated the most significantly increased cryoprotection compared to DMSO alone. These findings present a potential method to improve the viability of cryopreserved mammalian cells.