Combined inhibition of CTPS1 and ATR is a metabolic vulnerability in p53-deficient myeloma cells.

In multiple myeloma, as in B-cell malignancies, mono- and especially bi-allelic gene inactivation is a high-risk factor for treatment resistance, and there are currently no therapies specifically targeting p53 deficiency. In this study, we evaluated if the loss of cell cycle control in p53-deficient myeloma cells would confer a metabolically actionable vulnerability. We show that CTP synthase 1 (), which encodes a CTP synthesis rate-limiting enzyme essential for DNA and RNA synthesis in lymphoid cells, is overexpressed in samples from myeloma patients displaying a high proliferation rate (high expression) or a low p53 score (synonymous with deletion and/or mutation).

Unraveling MCL biology to understand resistance and identify vulnerabilities.

Mantle cell lymphoma (MCL) is a rare (5-7%), aggressive B-cell non-Hodgkin's lymphoma with well-defined hallmarks (e.g. Cyclin D1, SOX11), and whose expansion is highly dependent on the tumor microenvironment (TME).

Ibrutinib, obinutuzumab, and venetoclax in relapsed and untreated patients with mantle cell lymphoma: a phase 1/2 trial.

Ibrutinib, obinutuzumab, and venetoclax demonstrate synergy in preclinical models of mantle cell lymphoma (MCL). OAsIs (NCT02558816), a single-arm multicenter prospective phase 1/2 trial, aimed to determine the maximum tolerated dose of venetoclax in combination with fixed doses of ibrutinib and obinutuzumab, in relapsed MCL patients. At the venetoclax MTD, extension cohorts were opened for relapsed and untreated patients.

Restoring Apoptosis with BH3 Mimetics in Mature B-Cell Malignancies.

Apoptosis is a highly conserved mechanism enabling the removal of unwanted cells. Mitochondrial apoptosis is governed by the B-cell lymphoma (BCL-2) family, including anti-apoptotic and pro-apoptotic proteins. Apoptosis evasion by dysregulation of anti-apoptotic BCL-2 members (BCL-2, MCL-1, BCL-X) is a common hallmark in cancers.

Stabilization of β-catenin upon B-cell receptor signaling promotes NF-kB target genes transcription in mantle cell lymphoma.

B-cell receptor (BCR) signaling pathways and interactions with the tumor microenvironment account for mantle cell lymphoma (MCL) cells survival in lymphoid organs. In several MCL cases, the WNT/β-catenin canonical pathway is activated and β-catenin accumulates into the nucleus. As both BCR and β-catenin are important mediators of cell survival and interaction with the microenvironment, we investigated the crosstalk between BCR and WNT/β-catenin signaling and analyzed their impact on cellular homeostasis as well as their targeting by specific inhibitors.

Pannexin-1 limits the production of proinflammatory cytokines during necroptosis.

The activation of mixed lineage kinase-like (MLKL) by receptor-interacting protein kinase-3 (RIPK3) controls the execution of necroptosis, a regulated form of necrosis that occurs in apoptosis-deficient conditions. Active oligomerized MLKL triggers the exposure of phosphatidylserine residues on the cell surface and disrupts the plasma membrane integrity by forming lytic pores. MLKL also governs endosomal trafficking and biogenesis of small extracellular vesicles as well as the production of proinflammatory cytokines during the early steps of necroptosis; however, the molecular basis continues to be elucidated.

CSF1R and BTK inhibitions as novel strategies to disrupt the dialog between mantle cell lymphoma and macrophages.

The microenvironment strongly influences mantle cell lymphoma (MCL) survival, proliferation, and chemoresistance. However, little is known regarding the molecular characterization of lymphoma niches. Here, we focused on the interplay between MCL cells and the associated monocytes/macrophages.

BCL2-Family Dysregulation in B-Cell Malignancies: From Gene Expression Regulation to a Targeted Therapy Biomarker.

BCL2-family proteins have a central role in the mitochondrial apoptosis machinery and their expression is known to be deregulated in many cancer types. Effort in the development of small molecules that selectively target anti-apoptotic members of this family i.e.

Whole-exon sequencing of human myeloma cell lines shows mutations related to myeloma patients at relapse with major hits in the DNA regulation and repair pathways.

Background: Human myeloma cell lines (HMCLs) are widely used for their representation of primary myeloma cells because they cover patient diversity, although not fully. Their genetic background is mostly undiscovered, and no comprehensive study has ever been conducted in order to reveal those details.

Methods: We performed whole-exon sequencing of 33 HMCLs, which were established over the last 50 years in 12 laboratories.

p53 regulates CD46 expression and measles virus infection in myeloma cells.

In this study, we assessed the sensitivity of myeloma cells to the oncolytic measles virus (MV) in relation to p53 using 37 cell lines and 23 primary samples. We showed that infection and cell death were correlated with CD46 expression, which was associated with status; cell lines highly expressed CD46 and were preferentially infected by MV when compared with the cell lines ( = .046 and = .

Crosstalk between ROR1 and BCR pathways defines novel treatment strategies in mantle cell lymphoma.

Mantle cell lymphoma (MCL) is an aggressive form of non-Hodgkin B-cell lymphoma with poor prognosis due to drug resistance. Introduction of the Bruton tyrosine kinase (BTK) inhibitor ibrutinib has markedly improved MCL therapy outcome, but drug resistance remains a challenge. The selective cell-surface expression of oncogenic receptor tyrosine kinase-like orphan receptor 1 (ROR1) pseudokinase in hematological malignancies has made this receptor a promising candidate for targeted therapy.

Decitabine and Melphalan Fail to Reactivate p73 in p53 Deficient Myeloma Cells.

(1) Background: deficiency remains a major adverse event in Multiple Myeloma (MM) despite therapeutic progresses. As it is not possible to target deficiency with pharmacological agents, we explored the possibility of activating another p53 family member, p73, which has not been well studied in myeloma. (2) Methods: Using human myeloma cell lines (HMCLs) with normal or abnormal status, we assessed methylation and expression.

Rationale for targeting tumor cells in their microenvironment for mantle cell lymphoma treatment.

Mantle cell lymphoma (MCL) is an aggressive non-Hodgkin lymphoma associated with poor prognosis, and despite recent improvements in the therapeutic strategies for treating MCL, its management remains challenging. While improvements in next generation sequencing technology have greatly increased our understanding of the intrinsic abnormalities of MCL, the role of extrinsic signaling remains largely unknown. Recent studies have highlighted the central role of the MCL microenvironment in tumor cell survival, drug resistance and proliferation.

p53 dysregulation in B-cell malignancies: More than a single gene in the pathway to hell.

TP53 deletion or mutation is frequent in B-cell malignancies and is associated with a low response rate. We describe here the p53 landscape in B-cell malignancies, from B-Acute Lymphoblastic Leukemia to Plasma Cell Leukemia, by analyzing incidence of gain or loss of function of actors both upstream and within the p53 pathway, namely MYC, RAS, ARF, MDM2, ATM and TP53. Abnormalities are not equally distributed and their incidence is highly variable among malignancies.