Identification of stromal proteins overexpressed in nodular sclerosis Hodgkin lymphoma

The extracellular matrix: A key player in the pathogenesis of hematologic malignancies

Hematopoietic stem and progenitor cells located in the bone marrow lay the foundation for multiple lineages of mature hematologic cells. Bone marrow niches are architecturally complex with specific cellular, physiochemical, and biomechanical factors. Increasing evidence suggests that the bone marrow microenvironment contributes to the pathogenesis of hematological neoplasms. Numerous studies have deciphered the role of genetic mutations and chromosomal translocations in the development hematologic malignancies. Significant progress has also been made in understanding how the cellular components and cytokine interactions within the bone marrow microenvironment promote the evolution of hematologic cancers. Although the extracellular matrix is known to be a key player in the pathogenesis of various diseases, it's role in the progression of hematologic malignancies is less understood. In this review, we discuss the interactions between the extracellular matrix and malignant cells, and provide an overview of the role of extracellular matrix remodeling in sustaining hematologic malignancies.

Proteomic Profiles and Biological Processes of Relapsed vs. Non-Relapsed Pediatric Hodgkin Lymphoma

The identification of circulating proteins associated with relapse in pediatric Hodgkin lymphoma (HL) may help develop predictive biomarkers. We previously identified a set of predictive biomarkers by difference gel electrophoresis. Here we used label-free quantitative liquid chromatography-mass spectrometry (LC-MS/MS) on plasma collected at diagnosis from 12 children (age 12–16 years) with nodular sclerosis HL, including six in whom the disease relapsed within 5 years of treatment in the LH2004 trial. Plasma proteins were pooled in groups of three, separately for non-relapsing and relapsing HL, and differentially abundant proteins between the two disease states were identified by LC-MS/MS in an explorative and validation design. Proteins with a fold change in abundance >1.2 or ≤0.8 were considered “differentially abundant”. LC-MS/MS identified 60 and 32 proteins that were more abundant in non-relapsing and relapsing HL plasma, respectively, in the explorative phase; these numbers were 39 and 34 in the validation phase. In both analyses, 11 proteins were more abundant in non-relapsing HL (e.g., angiotensinogen, serum paraoxonase/arylesterase 1, transthyretin), including two previously identified by difference gel electrophoresis (antithrombin III and α-1-antitrypsin); seven proteins were more abundant in relapsing HL (e.g., fibronectin and thrombospondin-1), including two previously identified proteins (fibrinogen β and γ chains). The differentially abundant proteins participated in numerous biological processes, which were manually grouped into 10 biological classes and 11 biological regulatory subclasses. The biological class Lipid metabolism, and its regulatory subclass, included angiotensinogen and serum paraoxonase/arylesterase 1 (more abundant in non-relapsing HL). The biological classes Immune system and Cell and extracellular matrix architecture included fibronectin and thrombospondin-1 (more abundant in relapsing HL). These findings deepen our understanding of the molecular scenario underlying responses to therapy and provide new evidence about these proteins as possible biomarkers of relapse in pediatric HL.

Cell-secreted signals shape lymphoma identity

Sequencing data show that both specific genes and a number of signaling pathways are recurrently mutated in various types of lymphoma. DNA sequencing analyses of lymphoma have identified several aberrations that might affect the interaction between malignant cells and the tumor microenvironment. Microenvironmental functions are essential to lymphoma; they provide survival and proliferation signals and license immune evasion. It is plausible that interventions that aim to destroy tumor-microenvironment interactions may improve responses to therapeutics. Accordingly, the identification of extrinsic factors and their downstream intracellular signaling targets has led to much progress in understanding tumor-microenvironment interactions. Lymphoma cells are differently influenced by cells' interactions with components of their microenvironment; these cell extrinsic factors include soluble and immobilized factors, the extracellular matrix, and signals presented by neighboring cells. Soluble factors, which are often cell-secreted autocrine and paracrine factors, comprise a significant fraction of targetable molecules. To begin to understand how intercellular communication is conducted in lymphoma, a first order of study is deciphering the soluble factors secreted by malignant cells and microenvironmental cells. These soluble factors are shed into the interstitial fluid in lymphoma and can be conveniently explored using mass spectrometry. Protein components can be detected and quantified, thus enabling the routine navigation of the soluble part of the microenvironment. Elucidating functional and signaling states affords a new paradigm for understanding cancer biology and devising new therapies. This review summarizes knowledge in this field and discusses the utility of studying tumor-secreted factors.