Bertolazzi, G. | Search bioRxiv

bioRxiv2024

B cell receptor silencing reveals the origin of high-grade B cell lymphomas with MYC and BCL2 rearrangements

The B cell receptor (BCR) is essential for mature B cell lymphomas, serving as therapeutic target. Here, we show that high-grade B cell lymphomas with MYC and BCL2 rearrangements (HGBCL-DH-BCL2) predominantly exhibit immunoglobulin heavy (IGH) chain silencing, leading to BCR shutdown. HGBCL-DH-BCL2 with undetectable IGH (IGHUND) differ from IGH-expressing counterparts for germinal center-zone gene programs, MYC expression and T cell infiltration. While IGH+ HGBCL-DH-BCL2 prefer IGM/IG-Kappa expression, IGHUND counterparts have completed IGH class-switching, favoring IG-Lambda (IGL) light chains. IGHUND HGBCL-DH-BCL2 preserve IGHV gene integrity, overcoming antigen-driven selection. IGH silencing precedes onset and shapes evolution of HGBCL-DH-BCL2 from Follicular Lymphoma (FL) or FL/HGBCL-DH-BCL2 common precursor. In FL/HGBCL-DH-BCL2 pairs and HGBCL-DH-BCL2 models, BCR silencing promoted RAG1/2-dependent IG light chain editing, causing t(8;22)(q24;q11)/IGL::MYC. IGH silencing protected HGBCL-DH-BCL2 models from killing by CD79B-targeting Polatuzumab-Vedotin. Collectively, HGBCL-DH-BCL2 primarily originate from BCR-silenced isotype-switched t(14;18)/IGH::BCL2-positive (pre)FL cells acquiring IGL::MYC translocations during IG light chain revision, with clinical implications. SignificanceThese findings link BCR silencing in isotype-switched t(14;18)+ Follicular Lymphoma cells (or their precursors) to RAG1/2 re-expression, promoting IGL::MYC translocations responsible for transformation into high-grade B cell lymphomas (HGBCL). Predominant silencing of the BCR complex in HGBCL with MYC and BCL2 rearrangements protects tumor cells from CD79B-directed Polatuzumab-Vedotin killing.

cancer biology↗

bioRxiv2023

PARP-1, EpCAM, and FRα as potential targets for intraoperative detection and delineation of endometriosis: a quantitative tissue expression analysis

Endometriosis is a gynecological disease characterized by the presence of endometrial tissue in abnormal locations, leading to severe symptoms, inflammation, pain, organ dysfunction, and infertility. Surgical removal of endometriosis lesions is crucial for improving pain and fertility outcomes, with the goal of complete lesion removal. Incomplete surgery often results in recurring symptoms and the need for additional interventions. This study aims to explore the biological significance of PARP-1, EpCAM, and FR as potential targets for molecular imaging in endometriosis, assessing their suitability for targeted intraoperative imaging. Gene expression analysis was performed using the EndometDB. By immunohistochemistry, we investigated the presence and distribution of PARP-1, EpCAM, and FR in endometriosis foci and adjacent tissue. We also applied an ad hoc platform for the analysis image to perform a quantitative immunolocalization analysis. Additionally, double immunofluorescence analysis was carried out for PARP-1 and EpCAM, as well as PARP-1 and FR, to explore the expression of these combined markers within endometriosis foci and their potential simultaneous utilization in surgical treatment. The analysis of gene expression revealed that PARP-1, EpCAM, and FR exhibit higher levels of expression in endometriotic lesions compared to the peritoneum, used for control tissue. Immunohistochemical analysis also highlighted a significant increase in expression of all three biomarkers in endometriosis foci compared to surrounding tissues, as well as the quantitative analysis of immunolocalization of the signal. Furthermore, the double immunofluorescence analysis consistently revealed nuclear expression of PARP-1 and membrane and cytoplasmatic expression of EpCAM and FR, although relatively weaker. Overall, the three markers demonstrate significant potential for effective imaging of endometriosis. Particularly, the results emphasize the importance of PARP-1 expression as a possible indicator for distinguishing endometriotic lesions from adjacent tissue. PARP-1, as a potential biomarker for endometriosis, offers promising avenues for further investigation in terms of both pathophysiology and diagnostic-therapeutic approaches.

cell biology↗