Down-regulation of CD9 expression and its correlation to tumor progression in B lymphomas

Aged fibroblast-derived extracellular vesicles promote angiogenesis in melanoma

Advancing age is a negative prognostic factor for cutaneous melanoma. However, the role of extracellular vesicles (EVs) within the melanoma tumor microenvironment (TME) has remained unexplored in the context of aging. While the size and morphology of the EVs isolated from young vs. aged fibroblasts remained unaltered, the contents of the protein cargo were changed. Aging reduced the expression of the tetraspanin CD9 in both the dermal fibroblasts and released EVs. CD9 is a crucial regulator of EV cargo sorting. Modulating the CD9 expression in fibroblasts was sufficient to alter its levels in EVs. Mass spectrometry analysis of EVs released by CD9 knockdown (KD) vs. control cells revealed a significant increase in angiopoietin-like protein 2 (ANGPTL2), an angiogenesis promoter. Analysis of primary endothelial cells confirmed increased sprouting under CD9 KD conditions. Together, our data indicate that aged EVs play an important role in promoting a tumor-permissive microenvironment.

Exosomal derived miR-1246 from hydroquinone-transformed cells drives S phase accumulation arrest by targeting cyclin G2 in TK6 cells

BACKGROUND

Hydroquinone (HQ), a major metabolite of benzene and known hematotoxic carcinogen. MicroRNA 1246 (miR-1246), an oncogene, regulates target genes in carcinogenesis including leukemia. This study investigates the impact of exosomal derived miR-1246 from HQ-transformed (HQ19) cells on cell-to-cell communication in recipient TK6 cells.

METHODS

RNA sequencing was used to identify differentially expressed exosomal miRNAs in HQ19 cells and its phosphate buffered solution control cells (PBS19), which were then confirmed using qRT-PCR. The impact of exosomal miR-1246 derived from HQ-transformed cells on cell cycle distribution was investigated in recipient TK6 cells.

RESULTS

RNA sequencing analysis revealed that 34 exosomal miRNAs were upregulated and 158 miRNAs were downregulated in HQ19 cells compared with PBS19 cells. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses predicted that their targets are enriched in cancer development-related pathways, such as MAPK signaling, microRNAs in cancer, apoptosis, PI3K-Akt signaling, cell cycle, Ras signaling, and Chronic myeloid leukemia. Eleven miRNAs were confirmed to have differential expression through qRT-PCR, with 6 upregulated (miR-140-3p, miR-551b-3p, miR-7-5p, miR-1290, miR-92a-3p, and miR-1246) and 5 downregulated (miR-183-5p, miR-26a-5p, miR-30c-5p, miR-205-5p, and miR-99b-3p). Among these, miR-1246 exhibited the highest expression level. HQ exposure resulted in a concentration-dependent increase in miR-1246 levels and decrease Cyclin G2 (CCNG2) levels in TK6 cells. Similarly, exosomes from HQ19 exhibited similar effects as HQ exposure. Dual luciferase reporter gene assays indicated that miR-1246 could band to CCNG2. After HQ exposure, exosomal miR-1246 induced cell cycle arrest at the S phase, elevating the expression of genes like pRb, E2F1, and Cyclin D1 associated with S phase checkpoint. However, silencing miR-1246 caused G2/M-phase arrest.

CONCLUSION

HQ-transformed cells' exosomal miR-1246 targets CCNG2, regulating TK6 cell cycle arrest, highlighting its potential as a biomarker for HQ-induced malignant transformation.

Molecular Mechanisms in Murine Syngeneic Leukemia Stem Cells

Acute Myeloid Leukemia (AML) is a severe disease with a very high relapse rate. AML relapse may be attributable to leukemic stem cells (LSC). Notably, the "cancer stem cell" theory, which relates to LSCs, is controversial and criticized due to the technical peculiarities of the xenotransplant of human cells into mice. In this study, we searched for possible LSCs in an immunocompetent synergetic mice model. First, we found phenotypic heterogeneity in the ML23 leukemia line. We prospectively isolated a sub-population using the surface markers cKit⁺CD9^-CD48⁺Mac1^-/low, which have the potency to relapse the disease. Importantly, this sub-population can pass in syngeneic hosts and retrieve the heterogeneity of the parental ML23 leukemia line. The LSC sub-population resides in various organs. We present a unique gene expression signature of the LSC in the ML23 model compared to the other sub-populations. Interestingly, the ML23 LSC sub-population expresses therapeutic targeted genes such as CD47 and CD93. Taken together, we present the identification and molecular characterization of LSCs in a syngeneic murine model.

Large-Scale Proteomic Analysis of Follicular Lymphoma Reveals Extensive Remodeling of Cell Adhesion Pathway and Identifies Hub Proteins Related to the Lymphomagenesis

Simple Summary

Follicular lymphoma represents the major subtype of indolent B-cell non-Hodgkin lymphomas, ranging from about 20 to 30% of all B-NHLs cases in western countries. Yet, the global proteome profile of follicular lymphoma remains largely undocumented; thus, we aimed to employ for the first time a comprehensive proteomic analysis to outline its molecular landscape. A total of 15 lymphoma fine-needle aspiration biopsy samples and 14 controls were evaluated by label-free quantitative proteomics. Among the 7673 proteins identified in our dataset, 1186 proteins were differentially expressed between lymphoma and control samples. Importantly, dysregulated proteins were enriched in biological processes such as B-cell receptor signaling pathway, cellular adhesion molecules pathway, or membrane trafficking. Additionally, we identified several novel hub proteins related to lymphomagenesis. To summarize, we have determined the molecular characteristics of follicular lymphoma and discovered proteins which may hold potential for biomarkers or therapeutic targets.

Abstract

Follicular lymphoma (FL) represents the major subtype of indolent B-cell non-Hodgkin lymphomas (B-NHLs) and results from the malignant transformation of mature B-cells in lymphoid organs. Although gene expression and genomic studies have identified multiple disease driving gene aberrations, only a few proteomic studies focused on the protein level. The present work aimed to examine the proteomic profiles of follicular lymphoma vs. normal B-cells obtained by fine-needle aspiration biopsy (FNAB) to gain deep insight into the most perturbed pathway of FL. The cells of interest were purified by magnetic-activated cell sorting (MACS). High-throughput proteomic profiling was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and allowed to identify of 6724 proteins in at least 75% of each group of samples. The ‘Total Protein Approach’ (TPA) was applied to the absolute quantification of proteins in this study. We identified 1186 differentially abundant proteins (DAPs) between FL and control samples, causing an extensive remodeling of several molecular pathways, including the B-cell receptor signaling pathway, cellular adhesion molecules, and PPAR pathway. Additionally, the construction of protein–protein interactions networks (PPINs) and identification of hub proteins allowed us to indicate the key player proteins for FL pathology. Finally, ICAM1, CD9, and CD79B protein expression was validated in an independent cohort by flow cytometry (FCM), and the results were consistent with the mass spectrometry (MS) data.

How Biophysical Forces Regulate Human B Cell Lymphomas

The role of microenvironment-mediated biophysical forces in human lymphomas remains elusive. Diffuse large B cell lymphomas (DLBCLs) are heterogeneous tumors, which originate from highly proliferative germinal center B cells. These tumors, their associated neo-vessels, and lymphatics presumably expose cells to particular fluid flow and survival signals. Here, we show that fluid flow enhances proliferation and modulates response of DLBCLs to specific therapeutic agents. Fluid flow upregulates surface expression of B cell receptors (BCRs) and integrin receptors in subsets of ABC-DLBCLs with either CD79A/B mutations or WT BCRs, similar to what is observed with xenografted human tumors in mice. Fluid flow differentially upregulates signaling targets, such as SYK and p70S6K, in ABC-DLBCLs. By selective knockdown of CD79B and inhibition of signaling targets, we provide mechanistic insights into how fluid flow mechanomodulates BCRs and integrins in ABC-DLBCLs. These findings redefine microenvironment factors that regulate lymphoma-drug interactions and will be critical for testing targeted therapies.

Exosomal tetraspanins as regulators of cancer progression and metastasis and novel diagnostic markers

Exosomes are cell-cell communicators emerging as a new paradigm for noninvasive diagnosis and prognosis of treatment response. Exosomal tetraspanin proteins like CD63, CD9 and CD81 play a critical role in sorting, selective recruitment of biomolecules, target selection, cell-specific entry, capturing, angiogenesis and vasculogenesis. These tetraspanins are being used as markers for oral, colorectal and colon cancers and glioblastoma. However, exosomal markers with robust specificity for early detection of carcinomas are the furthest along. EXO CARTA database shows the presence of CD151 in exosomes of colorectal, melanoma, ovarian and prostate cancers. CD151 preferentially targets exosomes to lung, lymph node and stroma cells. The present review discussed the possible role of tetraspanins in the formation, cargo selection, target selection and uptake of exosomes and suggests exciting new directions for future research.

The Expression of CD9 and PIK3CD is Associated with Prognosis of Follicular Lymphoma

BACKGROUND

Follicular lymphoma (FL) frequently develops drug-resistance and transforms into more aggressive subtypes over time. It is urgent to find prognostic biomarkers and disclose signaling pathways that have potential to be drug targets. In this study, we investigated the association of FL prognosis with the expression of 2 proteins: PIK3CD, a PI3K pathway component, and CD9, a tetraspanin family member.

METHOD

The expression of PIK3CD and CD9 were examined on 76 FL tumor tissues and 15 normal tissues with Immunohistochemistry. Chi-square test, Cox proportional hazards model, and Kaplan-Meier estimates were used to analyze the relationships of CD9 and PIK3CD expression and major clinicopathological features.

RESULT

PIK3CD expression was significantly higher, whereas CD9 expression was significantly lower in the 76 FL specimens than normal tissues. Concomitantly, low CD9 or high PIK3CD expression is associated with high degrees of Ann Arbor stages. In agreement with this, PIK3CD is an unfavorable and CD9 is a favorable factor for progression-free survival (PFS). Interestingly, PIK3CD expression is negatively correlated with CD9 expression, and the PIK3CD-high/CD9-low was significantly associated with short PFS when the 2 factors were combined together. Lastly, CD9 expression was significant higher in patients with bone marrow infiltration (BMI) than those without BMI.

CONCLUSION

Both CD9 and PIK3CD are prognostic markers of FL. The negative correlation between CD9 and PIK3CD expression suggests that there may be crosstalks of the 2 proteins in FL.

CD9 may contribute to the survival of human germinal center B cells by facilitating the interaction with follicular dendritic cells

The germinal center (GC) is a dynamic microenvironment where antigen (Ag)-activated B cells rapidly expand and differentiate, generating plasma cells (PC) that produce high-affinity antibodies. Precise regulation of survival and proliferation of Ag-activated B cells within the GC is crucial for humoral immune responses. The follicular dendritic cells (FDC) are the specialized stromal cells in the GC that prevent apoptosis of GC-B cells. Recently, we reported that human GC-B cells consist of CD9+ and CD9- populations and that it is the CD9+ cells that are committed to the PC lineage. In this study, we investigated the functional role of CD9 on GC-B cells. Tonsillar tissue section staining revealed that in vivo CD9+ GC-B cells localized in the light zone FDC area. Consistent this, in vitro CD9+ GC-B cells survived better than CD9- GC-B cells in the presence of HK cells, an FDC line, in a cell-cell contact-dependent manner. The frozen tonsillar tissue section binding assay showed that CD9+ GC-B cells bound to the GC area of tonsillar tissues significantly more than the CD9- GC-B cells did and that the binding was significantly inhibited by neutralizing anti-integrin β1 antibody. Furthermore, CD9+ cells bound to soluble VCAM-1 more than CD9- cells did, resulting in activation and stabilization of the active epitope of integrin β1. All together, our data suggest that CD9 on GC-B cells contributes to survival by strengthening their binding to FDC through the VLA4/VCAM-1 axis.

Cancer stem cell and stromal microenvironment

BACKGROUND

Chemotherapeutic resistance and local recurrence or distant organ metastasis are the major causes of cancer mortality. Conventional cancer treatments do not consistently prevent cancer recurrence.

METHODS

We illustrate the key roles that cancer stem cells and the tumor microenvironment-particularly the lymph node stromal microenvironment-play in tumor drug resistance, metastasis, and recurrence in 2 representative cancers: colorectal cancer and follicular lymphoma.

CONCLUSION

We believe that combination treatment with chemotherapeutic agents in conjunction with targeted therapies, such as stromal/cancer stem cell signaling-targeted therapy, may effectively minimize cancer recurrence.

Human tetraspanin transmembrane 4 superfamily member 4 or intestinal and liver tetraspan membrane protein is overexpressed in hepatocellular carcinoma and accelerates tumor cell growth

The human transmembrane 4 superfamily member 4 or intestinal and liver tetraspan membrane protein (TM4SF4/il-TMP) was originally cloned as an intestinal and liver tetraspan membrane protein and mediates density-dependent cell proliferation. The rat homolog of TM4SF4 was found to be up-regulated in regenerating liver after two-thirds hepatectomy and overexpression of TM4SF4 could enhance liver injury induced by CCl(4). However, the expression and significance of TM4SF4/il-TMP in liver cancer remain unknown. Here, we report that TM4SF4/il-TMP is frequently and significantly overexpressed in hepatocellular carcinoma (HCC). Real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis showed that TM4SF4/il-TMP mRNA and protein levels were up-regulated in ∼80% of HCC tissues. Immunohistochemical analysis of a 75 paired HCC tissue microarray revealed that TM4SF4/il-TMP was significantly overexpressed in HCC tissues (P< 0.001), and high immunointensity of TM4SF4/il-TMP tended to be in well-to-moderately differentiated HCC compared with poorly differentiated tumors. Functional studies showed that overexpression of TM4SF4/il-TMP in QGY-7701 and BEL-7404 HCC cell lines through stable transfection of TM4SF4 expression plasmid significantly promoted both cell growth and colony formation of HCC cells. Reduction of TM4SF4/il-TMP expression in QGY-7701 and BEL-7404 cells by stably transfecting TM4SF4 antisense plasmid caused great inhibition of cell proliferation. Our findings suggest that TM4SF4/il-TMP has the potential to be biomarker in HCC and plays a crucial role in promotion of cancer cell proliferation.

Expression of mesenchyme-specific gene signatures by follicular dendritic cells: insights from the meta-analysis of microarray data from multiple mouse cell populations

Follicular dendritic cells (FDC) are an important subset of stromal cells within the germinal centres of lymphoid tissues. They are specialized to trap and retain antigen-containing immune complexes on their surfaces to promote B-cell maturation and immunoglobulin isotype class-switching. However, little is known of the cell types from which FDC originate. To address fundamental questions associated with the relationships between FDC and other cell populations, we took advantage of the growing body of publicly available data for transcriptome analysis. We obtained a large number of gene expression data files from a range of different primary mouse cells and cell lines and subjected these data to network-based cluster analysis using BiolayoutExpress(3D) . Genes with related function clustered together in distinct regions of the graph and enabled the identification of transcriptional networks that underpin the functional activity of distinct cell populations. Several gene clusters were identified that were selectively expressed by cells of mesenchymal lineage and contained classic mesenchymal cell markers and extracellular matrix genes including various collagens, Acta2, Bgn, Fbn1 and Twist1. Our analysis showed that FDC also express highly many of these mesenchyme-associated genes. Promoter analysis of the genes comprising the mesenchymal clusters identified several regulatory motifs that are binding sites for candidate transcription factors previously known to be candidate regulators of mesenchyme-specific genes. Together, these data suggest FDC are a specialized mesenchymal cell population within the germinal centres of lymphoid tissues.

Transformation of follicular lymphoma

Histological transformation of follicular lymphoma (FL) to a more aggressive non-Hodgkin's lymphomas is a pivotal event in the natural history of FL and is associated with poor outcome. While commonly observed in clinical practice and despite multiple studies designed to address its pathogenesis, the biology of this process represents an enigma. In this chapter we present a state of the art review summarizing the definition of histologic transformation, its incidence, pathogenesis, clinical manifestations, treatment and outcome. Furthermore, we specifically emphasize gaps in our knowledge that should be addressed in future studies.