Project description:Deubiquitylases (DUBs) remove ubiquitin from proteins. In the context of cancer, their inhibition can induce the degradation of oncoproteins, that may otherwise be “undruggable”. Multiple myeloma (MM) is the second most common hematological malignancy with poor outcome and high sensitivity towards ubiquitin-proteasome-system (UPS) inhibitory therapies. However, the role of DUBs in MM pathophysiology and therapy has remained elusive. Starting from genetic screening for DUB dependencies in MM, we here identify OTUD6B as a central vulnerability in MM that drives the G1/S cell cycle transition by means of deubiquitylating and stabilizing LIN28B subsequent to LIN28B phosphorylation. LIN28B regulates miRNA biogenesis and exerts high expression in embryonic stem cells that becomes re-established in certain tumors, including MM. Binding of LIN28B at G1/S activates OTUD6B, which otherwise remains in a catalytically inactive state. As a consequence, stabilized LIN28B drives MYC expression via inhibition of let7 microRNAs, which in turn allows for a rapid transition of MM cells from G1 to S phase. Analyses of primary MM patient samples reveal a positive correlation of OTUDB6B expression with poor outcome, high MYC expression and MYC target gene induction, suggesting that high MYC levels in MM result from an activation of the OTUD6B-LIN28B nexus. Together, we here specify phosphorylation and cell cycle-dependent substrate binding as a means by which OTUD6B becomes activated to drive the G1/S transition via the LIN28B-MYC axis and nominate OTUD6B and LIN28B as actionable vulnerabilities in MM.

2022-10-12 | PXD027480 | Pride

MYC dependency in GLS1 and NAMPT is a therapeutic vulnerability in multiple myeloma

Project description:Multiple myeloma is an incurable hematological malignancy evolving from precursor states to advanced phases of the disease. MYC abnormalities play a critical role in the disease progression. Nevertheless, MYC lacks therapeutic drugability, thereby necessitating the exploration of alternative strategies aimed at circumventing the challenges associated with targeting MYC. In this study, we hypothesized that MYC upregulation induces genomic dependencies in tumor cells, creating vulnerabilities that can be exploited therapeutically. We discovered a differential dependency on glutamine metabolism in MYC overexpressing cells. We functionally explored these dependencies as a selective targetable vulnerability in vitro and in vivo. Furthermore, we uncovered a potential synergistic combination that can exacerbated this metabolic vulnerability, Collectively, our in vitro and in vivo results revealed an effective therapeutic combinatory strategy in the context of MYC overexpressing MM.

2024-04-09 | PXD050010 | Pride

Inhibition of the Aryl Hydrocarbon Receptor - Polyamine Biosynthesis Axis Suppresses Multiple Myeloma and prostate cancer progression

Project description:Polyamine inhibition for cancer therapy is, conceptually, an attractive approach but has yet to meet success in the clinical setting. The aryl hydrocarbon receptor (AHR) is the central transcriptional regulator of xenobiotic response. Our study revealed that AHR also positively regulated intracellular polyamine production via direct transcriptional activation of two genes (ODC1 and AZIN1) involved in polyamine biosynthesis and control, respectively. In multiple myeloma patients, AHR levels inversely correlated with survival, suggesting that AHR inhibition may be beneficial for treatment of this disease .We identified clofazimine, an FDA-approved anti-leprosy drug, as a potent AHR antagonist and a suppressor of polyamine biosynthesis. Experiments in a transgenic model of multiple myeloma (Vk*Myc mice) and in immunocompromised mice bearing multiple myeloma cell xenografts, revealed high efficacy of clofazimine comparable to that of bortezomib, a first-in-class proteasome inhibitor used for treatment of multiple myeloma. This study identified a previously unrecognized regulatory axis between AHR and polyamine metabolism and discovered clofazimine as an inhibitor of AHR and a potentially clinically-relevant anti-multiple myeloma agent. RNA-seq: human multiple myeloma MM1S and human normal fibroblasts WI38 cells -/+ CLF 2-4uM for 24hrs; -/+ shAHR

2018-07-18 | GSE117160 | GEO

Multiple Myeloma cells

Project description:Multiple Myeloma cells

| PRJNA800411 | ENA