Browsing by Author "Furdui, Cristina M"
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Item Open Access An FDA-Approved Antifungal, Ketoconazole, and Its Novel Derivative Suppress tGLI1-Mediated Breast Cancer Brain Metastasis by Inhibiting the DNA-Binding Activity of Brain Metastasis-Promoting Transcription Factor tGLI1.(Cancers, 2022-08) Doheny, Daniel; Manore, Sara; Sirkisoon, Sherona R; Zhu, Dongqin; Aguayo, Noah R; Harrison, Alexandria; Najjar, Mariana; Anguelov, Marlyn; Cox, Anderson O'Brien; Furdui, Cristina M; Watabe, Kounosuke; Hollis, Thomas; Thomas, Alexandra; Strowd, Roy; Lo, Hui-WenThe goal of this study is to identify pharmacological inhibitors that target a recently identified novel mediator of breast cancer brain metastasis (BCBM), truncated glioma-associated oncogene homolog 1 (tGLI1). Inhibitors of tGLI1 are not yet available. To identify compounds that selectively kill tGLI1-expressing breast cancer, we screened 1527 compounds using two sets of isogenic breast cancer and brain-tropic breast cancer cell lines engineered to stably express the control, GLI1, or tGLI1 vector, and identified the FDA-approved antifungal ketoconazole (KCZ) to selectively target tGLI1-positive breast cancer cells and breast cancer stem cells, but not tGLI1-negative breast cancer and normal cells. KCZ's effects are dependent on tGLI1. Two experimental mouse metastasis studies have demonstrated that systemic KCZ administration prevented the preferential brain metastasis of tGLI1-positive breast cancer and suppressed the progression of established tGLI1-positive BCBM without liver toxicities. We further developed six KCZ derivatives, two of which (KCZ-5 and KCZ-7) retained tGLI1-selectivity in vitro. KCZ-7 exhibited higher blood-brain barrier penetration than KCZ/KCZ-5 and more effectively reduced the BCBM frequency. In contrast, itraconazole, another FDA-approved antifungal, failed to suppress BCBM. The mechanistic studies suggest that KCZ and KCZ-7 inhibit tGLI1's ability to bind to DNA, activate its target stemness genes Nanog and OCT4, and promote tumor proliferation and angiogenesis. Our study establishes the rationale for using KCZ and KCZ-7 for treating and preventing BCBM and identifies their mechanism of action.Item Open Access Phosphorylation of guanosine monophosphate reductase triggers a GTP-dependent switch from pro- to anti-oncogenic function of EPHA4.(Cell chemical biology, 2022-06) Wolff, David W; Deng, Zhiyong; Bianchi-Smiraglia, Anna; Foley, Colleen E; Han, Zhannan; Wang, Xingyou; Shen, Shichen; Rosenberg, Masha M; Moparthy, Sudha; Yun, Dong Hyun; Chen, Jialin; Baker, Brian K; Roll, Matthew V; Magiera, Andrew J; Li, Jun; Hurley, Edward; Feltri, Maria Laura; Cox, Anderson O; Lee, Jingyun; Furdui, Cristina M; Liu, Liang; Bshara, Wiam; LaConte, Leslie EW; Kandel, Eugene S; Pasquale, Elena B; Qu, Jun; Hedstrom, Lizbeth; Nikiforov, Mikhail ASignal transduction pathways post-translationally regulating nucleotide metabolism remain largely unknown. Guanosine monophosphate reductase (GMPR) is a nucleotide metabolism enzyme that decreases GTP pools by converting GMP to IMP. We observed that phosphorylation of GMPR at Tyr267 is critical for its activity and found that this phosphorylation by ephrin receptor tyrosine kinase EPHA4 decreases GTP pools in cell protrusions and levels of GTP-bound RAC1. EPHs possess oncogenic and tumor-suppressor activities, although the mechanisms underlying switches between these two modes are poorly understood. We demonstrated that GMPR plays a key role in EPHA4-mediated RAC1 suppression. This supersedes GMPR-independent activation of RAC1 by EPHA4, resulting in a negative overall effect on melanoma cell invasion and tumorigenicity. Accordingly, EPHA4 levels increase during melanoma progression and inversely correlate with GMPR levels in individual melanoma tumors. Therefore, phosphorylation of GMPR at Tyr267 is a metabolic signal transduction switch controlling GTP biosynthesis and transformed phenotypes.Item Open Access Pyruvate dehydrogenase kinase supports macrophage NLRP3 inflammasome activation during acute inflammation.(Cell reports, 2023-01) Meyers, Allison K; Wang, Zhan; Han, Wenzheng; Zhao, Qingxia; Zabalawi, Manal; Duan, Likun; Liu, Juan; Zhang, Qianyi; Manne, Rajesh K; Lorenzo, Felipe; Quinn, Matthew A; Song, Qianqian; Fan, Daping; Lin, Hui-Kuan; Furdui, Cristina M; Locasale, Jason W; McCall, Charles E; Zhu, XueweiActivating the macrophage NLRP3 inflammasome can promote excessive inflammation with severe cell and tissue damage and organ dysfunction. Here, we show that pharmacological or genetic inhibition of pyruvate dehydrogenase kinase (PDHK) significantly attenuates NLRP3 inflammasome activation in murine and human macrophages and septic mice by lowering caspase-1 cleavage and interleukin-1β (IL-1β) secretion. Inhibiting PDHK reverses NLRP3 inflammasome-induced metabolic reprogramming, enhances autophagy, promotes mitochondrial fusion over fission, preserves crista ultrastructure, and attenuates mitochondrial reactive oxygen species (ROS) production. The suppressive effect of PDHK inhibition on the NLRP3 inflammasome is independent of its canonical role as a pyruvate dehydrogenase regulator. Our study suggests a non-canonical role of mitochondrial PDHK in promoting mitochondrial stress and supporting NLRP3 inflammasome activation during acute inflammation.Item Open Access Regulation of local GTP availability controls RAC1 activity and cell invasion.(Nature communications, 2021-10) Bianchi-Smiraglia, Anna; Wolff, David W; Marston, Daniel J; Deng, Zhiyong; Han, Zhannan; Moparthy, Sudha; Wombacher, Rebecca M; Mussell, Ashley L; Shen, Shichen; Chen, Jialin; Yun, Dong-Hyun; O'Brien Cox, Anderson; Furdui, Cristina M; Hurley, Edward; Feltri, Maria Laura; Qu, Jun; Hollis, Thomas; Kengne, Jules Berlin Nde; Fongang, Bernard; Sousa, Rui J; Kandel, Mikhail E; Kandel, Eugene S; Hahn, Klaus M; Nikiforov, Mikhail APhysiological changes in GTP levels in live cells have never been considered a regulatory step of RAC1 activation because intracellular GTP concentration (determined by chromatography or mass spectrometry) was shown to be substantially higher than the in vitro RAC1 GTP dissociation constant (RAC1-GTP Kd). Here, by combining genetically encoded GTP biosensors and a RAC1 activity biosensor, we demonstrated that GTP levels fluctuating around RAC1-GTP Kd correlated with changes in RAC1 activity in live cells. Furthermore, RAC1 co-localized in protrusions of invading cells with several guanylate metabolism enzymes, including rate-limiting inosine monophosphate dehydrogenase 2 (IMPDH2), which was partially due to direct RAC1-IMPDH2 interaction. Substitution of endogenous IMPDH2 with IMPDH2 mutants incapable of binding RAC1 did not affect total intracellular GTP levels but suppressed RAC1 activity. Targeting IMPDH2 away from the plasma membrane did not alter total intracellular GTP pools but decreased GTP levels in cell protrusions, RAC1 activity, and cell invasion. These data provide a mechanism of regulation of RAC1 activity by local GTP pools in live cells.Item Open Access The fatty acid elongase ELOVL6 regulates bortezomib resistance in multiple myeloma(Blood Advances, 2021-04-13) Lipchick, Brittany C; Utley, Adam; Han, Zhannan; Moparthy, Sudha; Yun, Dong Hyun; Bianchi-Smiraglia, Anna; Wolff, David W; Fink, Emily; Liu, Liang; Furdui, Cristina M; Lee, Jingyun; Lee, Kelvin P; Nikiforov, Mikhail AAbstract Resistance to the proteasome inhibitor bortezomib (BTZ) represents a major obstacle in the treatment of multiple myeloma (MM). The contribution of lipid metabolism in the resistance of MM cells to BTZ is mostly unknown. Here we report that levels of fatty acid elongase 6 (ELOVL6) were lower in MM cells from BTZ-nonresponsive vs BTZ-responsive patients and in cultured MM cells selected for BTZ resistance compared with parental counterparts. Accordingly, depletion of ELOVL6 in parental MM cells suppressed BTZ-induced endoplasmic reticulum (ER) stress and cytotoxicity, whereas restoration of ELOVL6 levels in BTZ-resistant MM cells sensitized them to BTZ in tissue culture settings and, as xenografts, in a plasmacytoma mouse model. Furthermore, for the first time, we identified changes in the BTZ-induced lipidome between parental and BTZ-resistant MM cell lines underlying a functional difference in their response to BTZ. We demonstrated that restoration of ELOVL6 levels in BTZ-resistant MM cells resensitized them to BTZ largely via upregulation of ELOVL6-dependent ceramide species, which was a prerequisite for BTZ-induced ER stress and cell death in these cells. Our data characterize ELOVL6 as a major clinically relevant regulator of MM cell resistance to BTZ, which can emerge from the impaired ability of these cells to alter ceramide composition in response to BTZ.