Biology subjects

Kersten, M. J.

Publications and source records attributed to Kersten, M. J..

3 recordsLinked to original sources

bioRxiv2024

Targeting DOT1L and EZH2 synergizes in breaking the germinal center identity of Diffuse Large B Cell Lymphoma

Differentiation of antigen-activated B cells into pro-proliferative germinal center (GC) B cells depends on the activity of the transcription factor MYC and the epigenetic writers DOT1L and EZH2. GCB-like Diffuse Large B Cell Lymphomas (GCB-DLBCLs) arise from GC B cells and closely resemble their cell of origin. Given the dependency of GC B cells on DOT1L and EZH2, we investigated the role of these epigenetic regulators in GCB-DLBCL cell lines and observed that GCB-DLBCLs synergistically depend on the combined activity of DOT1L and EZH2. Mechanistically, inhibiting both enzymes led to enhanced derepression of PRC2 target genes compared to EZH2 single treatment, along with the suppression of MYC target genes. The sum of all these alterations results in a cell-identity crisis, wherein GCB-DLBCLs lose their pro-proliferative GC identity and partially undergo plasma cell differentiation, a state associated with poor survival. In support of this model, combined epi-drugging of DOT1L and EZH2 prohibited the outgrowth of human GCB-DLBCL xenografts in vivo. We conclude that the malignant behavior of GCB-DLBCLs strictly depends on DOT1L and EZH2 and that combined targeting of both epigenetic writers may provide an alternative differentiation-based treatment modality for GCB-DLBCL. Key pointsO_LIMYC-driven GCB-DLBCL depends on DOT1L and EZH2 and combined targeting provides an alternative differentiation-based therapy. C_LIO_LIDOT1L and EZH2 cooperatively repress PRC2 target genes which is essential for acquiring a plasma cell-like state in GC B cell-like DLBCL. C_LI

cancer biology↗

bioRxiv2022

Latent human herpesvirus 6 is reactivated in chimeric antigen receptor T cells

Cell therapies have yielded durable clinical benefits for patients with cancer, but the risks associated with the development of therapies from manipulated human cells are still being understood. For example, we currently lack a comprehensive understanding of the mechanisms of neurotoxicity observed in patients receiving T cell therapies, including recent reports of encephalitis caused by human herpesvirus 6 (HHV-6) reactivation1. Here, via petabase-scale viral RNA data mining, we examine the landscape of human latent viral reactivation and demonstrate that HHV-6B can become reactivated in human CD4+ T cells in standard in vitro cultures. Using single-cell sequencing, we identify a rare population of HHV-6 super-expressors (~1 in 300-10,000 cells) that possess high viral transcriptional activity in chimeric antigen receptor (CAR) T cell culture before spreading to infect other cells in vitro. Through the analysis of single-cell sequencing data from patients receiving cell therapy products that are FDA-approved2 or used in clinical studies3,4, we identify the presence of CAR+, HHV-6 super-expressor T cells in vivo. Together, our study implicates cell therapy products as a source of lytic HHV-6 reported in clinical trials1,5-7 and has broad implications for the design, production, and monitoring of cell therapies.

immunology↗

bioRxiv2020

The CXCL12gamma chemokine immobilized by heparan sulfate on stromal niche cells controls adhesion and mediates drug resistance in multiple myeloma

The homing/retention, survival and proliferation of multiple myeloma (MM) cells critically depends on interaction with CXCL12 expressing stromal cells in the bone marrow (BM) niche. Here, we report a unique role in this interaction for the recently characterized CXCL12gamma isoform, which contains an extended C-terminal domain that binds heparan-sulfate proteoglycans (HSPGs) with an extraordinary high affinity. We observed that CXCL12{gamma} is expressed in situ by reticular stromal cells in both normal and MM BM, as well as by primary BM stromal-cell (BMSC) isolates and BMSC lines. Importantly, upon secretion, CXCL12{gamma}, unlike the CXCL12 isoform, was retained on the surface of these BMSCs. This membrane retention of CXCL12{gamma} is HSPG-mediated, since it was completely annulated by CRISPR-Cas9 mediated deletion of the heparan-sulfate (HS) co-polymerase EXT1. Recombinant CXCL12{gamma} was found to induce strong adhesion of MM cells to vascular cell-adhesion molecule 1 (VCAM-1) coated plates. Furthermore, CXCL12{gamma} expressed by BMSCs and membrane-retained by HSPGs, supported robust adhesion of MM cells to the BMSCs. Specific genetic deletion of either CXCL12{gamma} or of EXT1 significantly attenuated the ability of BMSCs to support MM cell adhesion and, in addition, impaired their capacity to protect MM cells from bortezomib-induced cell death. Our data indicate that CXCL12{gamma} functions as a membrane-bound niche chemokine, which plays a unique role in the interaction of MM cells with the stromal niche by controlling adhesion/retention as well as cell adhesion-mediated drug resistance (CAM-DR). These findings designate CXCL12{gamma} and associated HSPGs as potential therapeutic targets in MM.

cancer biology↗