Genomic Alterations in Hodgkin's Lymphoma

Expression Profile of Selected Antitumor Immune Response Genes in Pediatric Classic Hodgkin Lymphoma

Classic Hodgkin lymphoma (cHL) is one of the most common pediatric solid tumors and is responsible for cancer-related deaths in children. Therefore, to modulate the active antitumor T-cell immune response in cHL can be a treatment strategy. In the present study, we aimed to investigate the expression profiles of selected antitumor immune response genes in pediatric cHL and their relationships with clinical and prognostic parameters to determine their significance in precision medicine. Thirty-nine pediatric nodal cHL patients were enrolled in the study. We analyzed mRNA expression of selected immune response regulatory genes such as PD-L1, CSF2, CTLA4, CXCL5, IDO1, CXCL8, MIF, NOS2, PDCD1, PTGS2, and TGFβ1 using real-time quantitative polymerase chain reaction. Only PD-L1 overexpression was statistically related to bulky disease, advanced tumor stage, and high-risk disease category and seen significantly in Epstein-Barr virus-negative pediatric cHL. No expression profiles were correlated with relapse or survival. We conclude that PD-L1 overexpression in pediatric cHL cases is a strong predictor of high-risk categorization. In addition to being a prognostic biomarker, PD-L1 blockade is also a druggable marker for the targeted therapy in Epstein-Barr virus-negative pediatric Hodgkin lymphoma.

Combination of two monoclonal antibodies with SOCS1 N- and C-terminal binding sites to address SOCS1 status in B cells and B-cell lymphoma

INTRODUCTION

Accumulating studies show that the tumour suppressor SOCS1 is one of the most frequently mutated genes in lymphomas, often affecting the coding sequence of SOCS1 protein. Depending on the type of mutation and lymphoma concerned, SOCS1 mutations have different impacts on progression-free and overall survival. Two antibodies binding the N and C terminals of SOCS1 would be a suitable 'test pair' to identify truncated versions of SOCS1. We, therefore, compared the C-terminal antibody 424C with the N-terminal antibody 4H1.

MATERIALS AND METHODS

As 424C has already been characterised, we performed a comparative analysis of anti-SOCS1 antibody 4H1 using immunohistochemistry on human tonsil tissue and chamber slides, immunoblots on SOCS1 wildtype and mutated transfected HEK293T cells and lymphoma cell lines and cross-reactivity analysis and epitope mapping with protein microarrays.

RESULTS

Compared with 424C, anti-SOCS1 antibody 4H1 showed various cross-reactions with other proteins resulting in a 'pancellular' immunohistochemical staining pattern in FFPE lymphoid tissue. Like 424C, 4H1 identified SOCS1 wildtype and SOCS1 mutations in immunoblot experiments but also bound an unknown protein with high intensity.

CONCLUSION

Anti-SOCS1 antibody 4H1 may be useful in a molecular setting but is disqualified as an immunohistochemical diagnostic tool due to its very broad non-specific binding.

A new reliable and highly specific monoclonal antibody to detect the C-terminal region of silencer of cytokine signaling 1

INTRODUCTION

SOCS1, a negative regulator of JAK/STAT signaling, is among the most frequently mutated genes in DLBCL and classical Hodgkin lymphoma. The C-terminal SOCS box domain, mediating the degradation of phospho-JAK2, is often affected or even lacking. The analysis of such variants is hampered by the lack of a SOCS1-specific monoclonal antibody recognizing the C-terminus of SOCS1. As this C-terminus is often lost or mutated in B-cell lymphomas, staining with amino-terminal targeting antibodies in a lymphoma setting might be misleading.

METHODS

BALB/c mice were immunized with a truncated SOCS1 C-terminal protein. The supernatant of generated hybridoma cells was screened by ELISA and, immunohistochemically, on formalin-fixed and paraffin-embedded tonsil. After antibody purification by affinity chromatography, epitope mapping and cross-reactivity check followed via substitution scans. SOCS1 protein expression was investigated on cell cultures and cytoblocks of SOCS1_WT stably transfected HEK293T cells, lymphoma cell lines and lymphoid tissues.

RESULTS

Procedures resulted in one monoclonal IgG1 anti-SOCS1 antibody, 424C, that recognizes and strongly binds to the C-terminal region of SOCS1 in immunoblot and immunohistochemistry analyses.

CONCLUSION

This new anti-SOCS1 monoclonal antibody is a valuable tool to detect SOCS1 expression dependent on an existing SOCS1 box and, therefore, indicating a full-length SOCS1 protein.

Genomic Landscape of Hodgkin Lymphoma

Simple Summary

Hodgkin lymphoma (HL) is composed of many reactive and only a few cancer cells, so-called Hodgkin and Reed-Sternberg (HRS) or lymphocyte predominant (LP) cells. Due to the scarcity of these cells, it was difficult to perform high-throughput molecular investigations on them for a long time. With the help of recently developed methods, it is now possible to analyze their genomes. This review summarizes the genetic alterations found in HRS and LP cells that impact immune evasion, proliferation and circumvention of programmed cell death in HL. Understanding these underlying molecular mechanisms is essential, as they may be of prognostic and predictive value and help to improve the therapy especially for patients with recurrent or treatment-resistant disease.

Abstract

Background: Hodgkin lymphoma (HL) is predominantly composed of reactive, non-neoplastic cells surrounding scarcely distributed tumor cells, that is, so-called Hodgkin and Reed-Sternberg (HRS) or lymphocyte predominant (LP) cells. This scarcity impeded the analysis of the tumor cell genomes for a long time, but recently developed methods (especially laser capture microdissection, flow cytometry/fluorescence-activated cell sorting) facilitated molecular investigation, elucidating the pathophysiological principles of “Hodgkin lymphomagenesis”. Methods: We reviewed the relevant literature of the last three decades focusing on the genomic landscape of classic and nodular lymphocyte predominant HL (NLPHL) and summarized molecular cornerstones. Results: Firstly, the malignant cells of HL evade the immune system by altered expression of PDL1/2, B2M and MHC class I and II due to various genetic alterations. Secondly, tumor growth is promoted by permanently activated JAK/STAT signaling due to pervasive mutations of multiple genes involved in the pathway. Thirdly, apoptosis of neoplastic cells is prevented by alterations of NF-κB compounds and the PI3K/AKT/mTOR axis. Additionally, Epstein-Barr virus infection can simultaneously activate JAK/STAT and NF-κB, similarly leading to enhanced survival and evasion of apoptosis. Finally, epigenetic phenomena such as promoter hypermethylation lead to the downregulation of B-lineage-specific, tumor-suppressor and immune regulation genes. Conclusion: The blueprint of HL genomics has been laid, paving the way for future investigations into its complex pathophysiology.

Nonclonal Chromosome Aberrations and Genome Chaos in Somatic and Germ Cells from Patients and Survivors of Hodgkin Lymphoma

Anticancer regimens for Hodgkin lymphoma (HL) patients include highly genotoxic drugs that have been very successful in killing tumor cells and providing a 90% disease-free survival at five years. However, some of these treatments do not have a specific cell target, damaging both cancerous and normal cells. Thus, HL survivors have a high risk of developing new primary cancers, both hematologic and solid tumors, which have been related to treatment. Several studies have shown that after treatment, HL patients and survivors present persistent chromosomal instability, including nonclonal chromosomal aberrations. The frequency and type of chromosomal abnormalities appear to depend on the type of therapy and the cell type examined. For example, MOPP chemotherapy affects hematopoietic and germ stem cells leading to long-term genotoxic effects and azoospermia, while ABVD chemotherapy affects transiently sperm cells, with most of the patients showing recovery of spermatogenesis. Both regimens have long-term effects in somatic cells, presenting nonclonal chromosomal aberrations and genomic chaos in a fraction of noncancerous cells. This is a source of karyotypic heterogeneity that could eventually generate a more stable population acquiring clonal chromosomal aberrations and leading towards the development of a new cancer.

Mechanisms underlying the association between obesity and Hodgkin lymphoma

A solid body of knowledge indicates that overweight and obese subjects are prone to develop cancer, aggressive disease, and death more than their lean counterparts. While obesity has been causally associated with various cancers, only a limited number of studies beheld the link with classical Hodgkin lymphoma (HL). Contemporary meta-analysis and prospective studies confirmed the association of body mass index with HL. Besides epidemiological evidence, excess adiposity is known to influence tumor behavior through adipokines, adipose-derived stem cell migration, and metabolism regulation, and by modulating immunoinflammatory response. Nevertheless, the obesity paradox has been described in few cancers. Considering that adipose tissue is an immunomodulatory organ, and that inflammation is the cornerstone of HL pathophysiology, the rationale for being causally related due to endocrine/paracrine interactions cannot be negligible. In this hypothesis-generating review, we explore the biologically plausible links between excess adiposity and HL in light of recent basic and clinical data, in order to create a basis for understanding the underlying mechanisms and foster applied research. The establishment of an association of excess adiposity with HL will determine public health preventive measures to fight obesity and eventually novel therapeutic approaches in HL patients.

Hodgkin lymphoma: pathology, pathogenesis, and a plethora of potential prognostic predictors

Hodgkin lymphoma (HL) encompasses 2 unique clinicopathologic entities, classical Hodgkin lymphoma (CHL) (∼95% of cases) and nodular lymphocyte predominant HL (∼5% of cases). Both subtypes demonstrate a paucity of surreptitious (in CHL) neoplastic B cells within a background of reactive inflammatory cells underscoring both the relatedness of these 2 entities to each other, as well as their distinction from other types of lymphoid neoplasia. Clinically, they are primarily nodal diseases that disseminate in a predictable manner to contiguous nodal regions. The biology of HL as a whole, as well as the genetic and pathologic features that distinguish CHL from nodular lymphocyte predominant HL and other lymphomas has been the subject of a wealth of investigation in recent decades. The aim of this review is to detail the pathologic features of HL and to highlight the recent insights into its molecular basis and the myriad prognostic markers being described.

Recent Advances in the Pathobiology of Hodgkin's Lymphoma: Potential Impact on Diagnostic, Predictive, and Therapeutic Strategies

From its first description by Thomas Hodgkin in 1832, Hodgkin's disease, now called Hodgkin's lymphoma, has continued to be a fascinating neoplasm even to this day. In this review, historical aspects, epidemiology, diagnosis, tumor biology, new observations related to host-microenvironment interactions, gene copy number variation, and gene expression profiling in this complex neoplasm are described, with an exploration of chemoresistance mechanisms and potential novel therapies for refractory disease.

Inactivating SOCS1 mutations are caused by aberrant somatic hypermutation and restricted to a subset of B-cell lymphoma entities

STATs are constitutively activated in several malignancies. In primary mediastinal large B-cell lymphoma and Hodgkin lymphoma (HL), inactivating mutations in SOCS1, an inhibitor of JAK/STAT signaling, contribute to deregulated STAT activity. Based on indications that the SOCS1 mutations are caused by the B cell–specific somatic hypermutation (SHM) process, we analyzed B-cell non-HL and normal B cells for mutations in SOCS1. One-fourth of diffuse large B-cell lymphoma and follicular lymphomas carried SOCS1 mutations, which were preferentially targeted to SHM hotspot motifs and frequently obviously inactivating. Rare mutations were observed in Burkitt lymphoma, plasmacytoma, and mantle cell lymphoma but not in tumors of a non–B-cell origin. Mutations in single-sorted germinal center B cells were infrequent relative to other genes mutated as byproducts of normal SHM, indicating that SOCS1 inactivation in primary mediastinal large B-cell lymphoma, HL, diffuse large B-cell lymphoma, and follicular lymphoma is frequently the result of aberrant SHM.

EBV and genomic instability--a new look at the role of the virus in the pathogenesis of Burkitt's lymphoma

Epidemiological and molecular evidence links Epstein-Barr virus (EBV) carriage to the pathogenesis of human malignancies of lymphoid and epithelial cell origin but the mechanisms of viral oncogenesis are poorly understood. Burkitt's lymphoma, a tumor occurring in both EBV-positive and -negative forms, provides a convenient model for analysis of the relative contribution of genetic changes and viral products that are expressed in the malignant cells. Here we review recent findings that highlight several mechanisms by which EBV could play an important role in oncogenesis by promoting genomic instability.

Somatic hypermutation of SOCS1 in lymphocyte-predominant Hodgkin lymphoma is accompanied by high JAK2 expression and activation of STAT6

Aberrant activities of JAK/STAT signaling pathways have been observed in several hematologic malignancies. Here, we show high expression of JAK2 in the tumor cells of lymphocyte-predominant Hodgkin lymphoma in 85% of cases and activation of JAK2 in 39% of cases. STAT6, which is a target of JAK2, was activated in 50% of the cases. SOCS1 controls JAK2 activity and degradation. Mutations in SOCS1 of either somatic or germ-line origin were observed in micromanipulated tumor cells of 50% of cases. Most mutations truncated SOCS1 or caused replacement of amino acids in functional important regions. Activating mutations in exon 12 of JAK2, which are frequent in myeloproliferative diseases, were not observed. In lymphocyte-predominant Hodgkin lymphoma SOCS1 function may thus be frequently impaired by mutations, and this may contribute to high JAK2 expression and activation of the JAK2/STAT6 pathway.