CD43, but not P-selectin glycoprotein ligand-1, functions as an E-selectin counter-receptor in human pre-B-cell leukemia NALL-1

The biology of E-selectin ligands in leukemogenesis

Both the cascade whereby a blood-borne cell enters a tissue and the anchoring of hematopoietic stem/progenitor cells (HSPCs) within bone marrow critically pivots on cell-cell interactions mediated by E-selectin binding to its canonical carbohydrate ligand, the tetrasaccharide termed "sialylated Lewis X" (sLeX). E-selectin, a member of the selectin class of adhesion molecules that is exclusively expressed by vascular endothelium, engages sLeX-bearing glycoconjugates that adorn mature leukocytes and HSPCs, as well as malignant cells, thereby permitting these cells to extravasate into various tissues. E-selectin expression is induced on microvascular endothelial cells within inflammatory loci at all tissues. However, conspicuously, E-selectin is constitutively expressed within microvessels in skin and marrow and, additionally, is inducibly expressed at these sites. Within the marrow, E-selectin receptor/ligand interactions promote lodgment of HSPCs and their malignant counterparts within hematopoietic growth-promoting microenvironments, collectively known as "vascular niches". Indeed, E-selectin receptor/ligand interactions have been reported to regulate both hematopoietic stem, and leukemic, cell proliferative dynamics. As such, signaling induced via engagement of E-selectin ligands is gaining interest as a critical mediator of homeostatic and malignant hematopoiesis, and this review will present current perspectives on the glycoconjugates mediating E-selectin receptor/ligand interactions and their currently defined role(s) in leukemogenesis.

CD43 is an adverse prognostic factor in newly diagnosed multiple myeloma

Currently, the expression pattern and prognostic value of CD43 expression in multiple myeloma (MM) remain unknown. 109 newly diagnosed MM patients were recruited and CD43 expression was determined by multiparameter flow cytometry, of which 77 (70.6%) were CD43 positive. Patients with positive CD43 expression were more likely to present with, hemoglobin < 85 g/L (p = 0.008), International Staging System (ISS) stage III (p = 0.044), 13q14 deletion (p = 0.034) and more monoclonal plasma cells (p = 0.003). Patients with CD43 positive had significantly poor treatment response (p = 0.021), progression-free survival (PFS) (p = 0.012), and overall survival (OS) (p = 0.023) than those without CD43. The poorer prognosis of CD43-positive patients was retained in multivariate analysis (p = 0.005 for PFS; p = 0.013 for OS). Our study indicated that CD43 was an independent adverse prognostic factor in multiple myeloma.

Targeting E-selectin to Tackle Cancer Using Uproleselan

E-selectin is a vascular adhesion molecule expressed mainly on endothelium, and its primary role is to facilitate leukocyte cell trafficking by recognizing ligand surface proteins. E-selectin gained a new role since it was demonstrated to be involved in cancer cell trafficking, stem-like properties and therapy resistance. Therefore, being expressed in the tumor microenvironment, E-selectin can potentially be used to eradicate cancer. Uproleselan (also known as GMI-1271), a specific E-selectin antagonist, has been tested on leukemia, myeloma, pancreatic, colon and breast cancer cells, most of which involve the bone marrow as a primary or as a metastatic tumor site. This novel therapy disrupts the tumor microenvironment by affecting the two main steps of metastasis-extravasation and adhesion-thus blocking E-selectin reduces tumor dissemination. Additionally, uproleselan mobilized cancer cells from the protective vascular niche into the circulation, making them more susceptible to chemotherapy. Several preclinical and clinical studies summarized herein demonstrate that uproleselan has favorable safety and pharmacokinetics and is a tumor microenvironment-disrupting agent that improves the efficacy of chemotherapy, reduces side effects such as neutropenia, intestinal mucositis and infections, and extends overall survival. This review highlights the critical contribution of E-selectin and its specific antagonist, uproleselan, in the regulation of cancer growth, dissemination, and drug resistance in the context of the bone marrow microenvironment.

L1CAM as an E-selectin Ligand in Colon Cancer

Metastasis is the main cause of death among colorectal cancer (CRC) patients. E-selectin and its carbohydrate ligands, including sialyl Lewis X (sLe^X) antigen, are key players in the binding of circulating tumor cells to the endothelium, which is one of the major events leading to organ invasion. Nevertheless, the identity of the glycoprotein scaffolds presenting these glycans in CRC remains unclear. In this study, we firstly have characterized the glycoengineered cell line SW620 transfected with the fucosyltransferase 6 (FUT6) coding for the α1,3-fucosyltransferase 6 (FUT6), which is the main enzyme responsible for the synthesis of sLe^X in CRC. The SW620FUT6 cell line expressed high levels of sLe^X antigen and E-selectin ligands. Moreover, it displayed increased migration ability. E-selectin ligand glycoproteins were isolated from the SW620FUT6 cell line, identified by mass spectrometry, and validated by flow cytometry and Western blot (WB). The most prominent E-selectin ligand we identified was the neural cell adhesion molecule L1 (L1CAM). Previous studies have shown association of L1CAM with metastasis in cancer, thus the novel role as E-selectin counter-receptor contributes to understand the molecular mechanism involving L1CAM in metastasis formation.

Acute Myeloid Leukemia Chemo-Resistance Is Mediated by E-selectin Receptor CD162 in Bone Marrow Niches

The interactions of leukemia cells with the bone marrow (BM) microenvironment is critical for disease progression and resistance to treatment. We have recently found that the vascular adhesion molecule E-(endothelial)-selectin is a key niche component that directly mediates acute myeloid leukemia (AML) chemo-resistance, revealing E-selectin as a promising therapeutic target. To understand how E-selectin promotes AML survival, we investigated the potential receptors on AML cells involved in E-selectin-mediated chemo-resistance. Using CRISPR-Cas9 gene editing to selectively suppress canonical E-selectin receptors CD44 or P-selectin glycoprotein ligand-1 (PSGL-1/CD162) from human AML cell line KG1a, we show that CD162, but not CD44, is necessary for E-selectin-mediated chemo-resistance in vitro. Using preclinical models of murine AML, we then demonstrate that absence of CD162 on AML cell surface leads to a significant delay in the onset of leukemia and a significant increase in sensitivity to chemotherapy in vivo associated with a more rapid in vivo proliferation compared to wild-type AML and a lower BM retention. Together, these data reveal for the first time that CD162 is a key AML cell surface receptor involved in AML progression, BM retention and chemo-resistance. These findings highlight specific blockade of AML cell surface CD162 as a potential novel niche-based strategy to improve the efficacy of AML therapy.

Emerging Role of Podocalyxin in the Progression of Mature B-Cell Non-Hodgkin Lymphoma

Mature B-cell non-Hodgkin lymphoma (B-NHL) constitutes a group of heterogeneous malignant lymphoproliferative diseases ranging from indolent to highly aggressive forms. Although the survival after chemo-immunotherapy treatment of mature B-NHL has increased over the last years, many patients relapse or remain refractory due to drug resistance, presenting an unfavorable prognosis. Hence, there is an urgent need to identify new prognostic markers and therapeutic targets. Podocalyxin (PODXL), a sialomucin overexpressed in a variety of tumor cell types and associated with their aggressiveness, has been implicated in multiple aspects of cancer progression, although its participation in hematological malignancies remains unexplored. New evidence points to a role for PODXL in mature B-NHL cell proliferation, survival, migration, drug resistance, and metabolic reprogramming, as well as enhanced levels of PODXL in mature B-NHL. Here, we review the current knowledge on the contribution of PODXL to tumorigenesis, highlighting and discussing its role in mature B-NHL progression.

Molecular Players in Hematologic Tumor Cell Trafficking

The trafficking of neoplastic cells represents a key process that contributes to progression of hematologic malignancies. Diapedesis of neoplastic cells across endothelium and perivascular cells is facilitated by adhesion molecules and chemokines, which act in concert to tightly regulate directional motility. Intravital microscopy provides spatio-temporal views of neoplastic cell trafficking, and is crucial for testing and developing therapies against hematologic cancers. Multiple myeloma (MM), chronic lymphocytic leukemia (CLL), and acute lymphoblastic leukemia (ALL) are hematologic malignancies characterized by continuous neoplastic cell trafficking during disease progression. A common feature of these neoplasias is the homing and infiltration of blood cancer cells into the bone marrow (BM), which favors growth and survival of the malignant cells. MM cells traffic between different BM niches and egress from BM at late disease stages. Besides the BM, CLL cells commonly home to lymph nodes (LNs) and spleen. Likewise, ALL cells also infiltrate extramedullary organs, such as the central nervous system, spleen, liver, and testicles. The α4β1 integrin and the chemokine receptor CXCR4 are key molecules for MM, ALL, and CLL cell trafficking into and out of the BM. In addition, the chemokine receptor CCR7 controls CLL cell homing to LNs, and CXCR4, CCR7, and CXCR3 contribute to ALL cell migration across endothelia and the blood brain barrier. Some of these receptors are used as diagnostic markers for relapse and survival in ALL patients, and their level of expression allows clinicians to choose the appropriate treatments. In CLL, elevated α4β1 expression is an established adverse prognostic marker, reinforcing its role in the disease expansion. Combining current chemotherapies with inhibitors of malignant cell trafficking could represent a useful therapy against these neoplasias. Moreover, immunotherapy using humanized antibodies, CAR-T cells, or immune check-point inhibitors together with agents targeting the migration of tumor cells could also restrict their survival. In this review, we provide a view of the molecular players that regulate the trafficking of neoplastic cells during development and progression of MM, CLL, and ALL, together with current therapies that target the malignant cells.

A functional glycoproteomics approach identifies CD13 as a novel E-selectin ligand in breast cancer

BACKGROUND

The glycan moieties sialyl-Lewis-X and/or -A (sLe^X/A) are the primary ligands for E-selectin, regulating subsequent tumor cell extravasation into distant organs. However, the nature of the glycoprotein scaffolds displaying these glycans in breast cancer remains unclear and constitutes the focus of the present investigation.

METHODS

We isolated glycoproteins that bind E-selectin from the CF1_T breast cancer cell line, derived from a patient with ductal carcinoma. Proteins were identified using bottom-up proteomics approach by nanoLC-orbitrap LTQ-MS/MS. Data were curated using bioinformatics tools to highlight clinically relevant glycoproteins, which were validated by flow cytometry, Western blot, immunohistochemistry and in-situ proximity ligation assays in clinical samples.

RESULTS

We observed that the CF1_T cell line expressed sLe^X, but not sLe^A and the E-selectin reactivity was mainly on N-glycans. MS and bioinformatics analysis of the targeted glycoproteins, when narrowed down to the most clinically relevant species in breast cancer, identified CD44 glycoprotein (HCELL) and CD13 as key E-selectin ligands. Additionally, the co-expression of sLe^X-CD44 and sLe^X-CD13 was confirmed in clinical breast cancer tissue samples.

CONCLUSIONS

Both CD44 and CD13 glycoforms display sLe^X in breast cancer and bind E-selectin, suggesting a key role in metastasis development. Such observations provide a novel molecular rationale for developing targeted therapeutics.

GENERAL SIGNIFICANCE

While HCELL expression in breast cancer has been previously reported, this is the first study indicating that CD13 functions as an E-selectin ligand in breast cancer. This observation supports previous associations of CD13 with metastasis and draws attention to this glycoprotein as an anti-cancer target.

T cell acute lymphoblastic leukemia (T-ALL): New insights into the cellular origins and infiltration mechanisms common and unique among hematologic malignancies

T-cell acute lymphoblastic leukemia (T-ALL) accounts for 15% and 25% of total childhood and adult ALL cases, respectively. During T-ALL, patients are at risk of organ infiltration by leukemic T-cells. Infiltration is a major consequence of disease relapse and correlates with poor prognosis. Transendothelial migration of leukemic cells is required to exit the blood stream into target organs. While mechanisms of normal T-cell transmigration are well known, the mechanisms of leukemic T-cell extravasation remain elusive; but involvement of chemokines, integrins and Notch signaling play critical roles. Here, we summarize current knowledge about molecular mechanisms of leukemic T-cell infiltration with special emphasis on the newly identified subtype early T-cell-progenitor (ETP)-ALL. Furthermore, we compare the extravasation potential of T-ALL cells with that of other hematologic malignancies such as B-ALL and acute myeloid leukemia (AML).

Microparticles as Biomarkers of Blood Coagulation in Cancer

Cancer is associated with hypercoagulopathy and increased risk of thrombosis. This negatively influences patient morbidity and mortality. Cancer is also frequently complicated by the development of venous thromboembolism (VTE). Tumor-derived tissue factor (TF)-bearing microparticles (MPs) are associated with VTE events in malignancy. MPs are small membrane vesicles released from many different cell types by exocytic budding of the plasma membrane in response to cellular activation or apoptosis. MPs may also be involved in clinical diseases through expression of procoagulative phospholipids. The detection of TF-expressing MPs in cancer patients may be clinically useful. In lung and breast cancer patients, MPs induce metastasis and angiogenesis and may be indicators of vascular complications. Additionally, MPs in patients with various types of cancer possess adhesion proteins and bind target cells to promoting cancer progression or metastasis. Overexpression of TF by cancer cells is closely associated with tumor progression, and shedding of TF-expressing MPs by cancer cells correlates with the genetic status of cancer. Consequently, TF-expressing MPs represent important markers to consider in the prevention of and therapy for VTE complications in cancer patients.

CD43 expression in diffuse large B-cell lymphoma, not otherwise specified: CD43 is a marker of adverse prognosis

CD43 (leukosialin) is a transmembrane glycoprotein expressed in a variety of hematopoietic cells, including B lymphocytes, and a variety of malignancies including lymphoma, leukemia, and solid tumors. CD43 plays an important role in the development of many diseases, and coexpression of CD43 and CD20 on peripheral B cells is a predictive factor of hematopoietic malignancy. Although CD43 is expressed in approximately 25% of diffuse large B-cell lymphomas (DLBCLs), its prognostic significance remains unclear. To analyze CD43 expression in DLBCL, not otherwise specified (DLBCL, NOS), and assess its prognostic value, we analyzed clinical data from 160 patients with DLBCL, NOS. We observed that CD43 expression was detected in 47 (29.4%) of 160 cases. CD43 expression was positively correlated with old age (>60 years), high serum lactate dehydrogenase level, B symptoms, non-germinal center type, and DLBCL, NOS, mortality. Patients with CD43-positive DLBCL, NOS, had poorer overall survival (P < .001, log-rank test) and event-free survival (P < .001, log-rank test) than CD43-negative patients. Univariate analysis showed that CD43 expression, age, sex, Ann Arbor stage, International Prognostic Index category, and germinal center phenotype were prognostic factors for DLBCL, NOS, patient survival. Multivariate analysis showed that CD43 expression was an independent significant prognostic factor for event-free survival (P < .001) and overall survival (P < .001). Based on these data, we conclude that CD43 expression is a novel adverse prognostic factor for patients with DLBCL, NOS.

RNA-seq Transcriptional Profiling of Peripheral Blood Leukocytes from Cattle Infected with Mycobacterium bovis

Bovine tuberculosis, caused by infection with Mycobacterium bovis, is a major endemic disease affecting cattle populations worldwide, despite the implementation of stringent surveillance and control programs in many countries. The development of high-throughput functional genomics technologies, including gene expression microarrays and RNA-sequencing (RNA-seq), has enabled detailed analysis of the host transcriptome to M. bovis infection, particularly at the macrophage and peripheral blood level. In the present study, we have analyzed the peripheral blood leukocyte (PBL) transcriptome of eight natural M. bovis-infected and eight age- and sex-matched non-infected control Holstein-Friesian animals using RNA-seq. In addition, we compared gene expression profiles generated using RNA-seq with those previously generated using the high-density Affymetrix^® GeneChip^® Bovine Genome Array platform from the same PBL-extracted RNA. A total of 3,250 differentially expressed (DE) annotated genes were detected in the M. bovis-infected samples relative to the controls (adjusted P-value ≤0.05), with the number of genes displaying decreased relative expression (1,671) exceeding those with increased relative expression (1,579). Ingenuity^® Systems Pathway Analysis (IPA) of all DE genes revealed enrichment for genes with immune function. Notably, transcriptional suppression was observed among several of the top-ranking canonical pathways including Leukocyte Extravasation Signaling. Comparative platform analysis demonstrated that RNA-seq detected a larger number of annotated DE genes (3,250) relative to the microarray (1,398), of which 917 genes were common to both technologies and displayed the same direction of expression. Finally, we show that RNA-seq had an increased dynamic range compared to the microarray for estimating differential gene expression.

The novel orally active proteasome inhibitor K-7174 exerts anti-myeloma activity in vitro and in vivo by down-regulating the expression of class I histone deacetylases

Bortezomib therapy is now indispensable for multiple myeloma, but is associated with patient inconvenience due to intravenous injection and emerging drug resistance. The development of orally active proteasome inhibitors with distinct mechanisms of action is therefore eagerly awaited. Previously, we identified homopiperazine derivatives as a novel class of proteasome inhibitors with a different mode of proteasome binding from bortezomib. In this study, we show that K-7174, one of proteasome inhibitory homopiperazine derivatives, exhibits a therapeutic effect, which is stronger when administered orally than intravenously, without obvious side effects in a murine myeloma model. Moreover, K-7174 kills bortezomib-resistant myeloma cells carrying a β5-subunit mutation in vivo and primary cells from a patient resistant to bortezomib. K-7174 induces transcriptional repression of class I histone deacetylases (HDAC1, -2, and -3) via caspase-8-dependent degradation of Sp1, the most potent transactivator of class I HDAC genes. HDAC1 overexpression ameliorates the cytotoxic effect of K-7174 and abrogates histone hyperacetylation without affecting the accumulation of ubiquitinated proteins in K-7174-treated myeloma cells. Conversely, HDAC inhibitors enhance the activity of K-7174 with an increase in histone acetylation. These results suggest that class I HDACs are critical targets of K-7174-induced cytotoxicity. It is highly anticipated that K-7174 increases the tolerability and convenience of patients by oral administration and has the clinical utility in overcoming bortezomib resistance as a single agent or in combination with HDAC inhibitors.

Selectins and Associated Adhesion Proteins in Inflammatory disorders

Inflammation is defined as the normal response of living tissue to injury or infection. It is important to emphasize two components of this definition. First, that inflammation is a normal response and, as such, is expected to occur when tissue is damaged. Infact, if injured tissue does not exhibit signs of inflammation this would be considered abnormal and wounds and infections would never heal without inflammation. Secondly, inflammation occurs in living tissue, hence there is need for an adequate blood supply to the tissues in order to exhibit an inflammatory response. The inflammatory response may be triggered by mechanical injury, chemical toxins, and invasion by microorganisms, and hypersensitivity reactions. Three major events occur during the inflammatory response: the blood supply to the affected area is increased substantially, capillary permeability is increased, and leucocytes migrate from the capillary vessels into the surrounding interstitial spaces to the site of inflammation or injury. The inflammatory response represents a complex biological and biochemical process involving cells of the immune system and a plethora of biological mediators. Cell-to-cell communication molecules such as cytokines play an extremely important role in mediating the process of inflammation. Inflammation and platelet activation are critical phenomena in the setting of acute coronary syndromes. An extensive exposition of this complex phenomenon is beyond the scope of this article (Rankin 2004).

Mammalian sialyltransferase ST3Gal-II: its exchange sialylation catalytic properties allow labeling of sialyl residues in mucin-type sialylated glycoproteins and specific gangliosides

While glycosyltransferases are known to display unidirectional enzymatic activity, recent studies suggest that some can also catalyze readily reversible reactions. Recently, we found that mammalian sialyltransferase ST3Gal-II can catalyze the formation of CMP-NeuAc from 5'-CMP in the presence of a donor containing the NeuAcα2,3Galβ1,3GalNAc unit [Chandrasekaran, E. V., et al. (2008) Biochemistry 47, 320-330]. This study shows by using [9-(3)H]- or [(14)C]sialyl mucin core 2 compounds that ST3Gal-II exchanges sialyl residues between CMP-NeuAc and the NeuAcα2,3Galβ1,3GalNAc unit and also radiolabels sialyl residues in gangliosides GD1a and GT1b, but not GM1. Exchange sialylation proceeds with relative ease, which is evident from the following. (a) Radiolabeleling of fetuin was ~2-fold stronger than that of asialo fetuin when CMP- [9-(3)H]NeuAc was generated in situ from 5'-CMP and [9-(3)H]NeuAcα2,3Galβ1,3GalNAcβ1,3Galα-O-Me by ST3Gal-II. (b) ST3Gal-II exchanged radiolabels between [(14)C]sialyl fetuin and [9-(3)H]NeuAcα2,3Galβ1,3GalNAcβ1,3Galα-O-Me by generating CMP-[(14)C]- and -[9-(3)H]NeuAc through 5'-CMP; only 20.3% (14)C and 28.0% (3)H remained with the parent compounds after the sialyl exchange. The [9-(3)H]sialyl-tagged MN glycophorin A, human chorionic gonadotropin β subunit, GlyCAM-1, CD43, fetuin, porcine Cowper's gland mucin, bovine casein macroglycopeptide, human placental glycoproteins, and haptoglobin were analyzed by using Pronase digestion, mild alkaline borohydride treatment, Biogel P6, lectin agarose, and silica gel thin layer chromatography. Sulfated and sialylated O-glycans were found in GlyCAM-1 and human placental glycoproteins. This technique has the potential to serve as an important tool as it provides a natural tag for the chemical and functional characterization of O-glycan-bearing glycoproteins.

CD44 and HCELL: preventing hematogenous metastasis at step 1

Despite great strides in our knowledge of the genetic and epigenetic changes underlying malignancy, we have limited information on the molecular basis of metastasis. Over 90% of cancer deaths are caused by spread of tumor cells from a primary site to distant organs and tissues, highlighting the pressing need to define the molecular effectors of cancer metastasis. Mounting evidence suggests that circulating tumor cells (CTCs) home to specific tissues by hijacking the normal leukocyte trafficking mechanisms. Cancer cells characteristically express CD44, and there is increasing evidence that hematopoietic cell E-/L-selectin ligand (HCELL), a sialofucosylated glycoform of CD44, serves as the major selectin ligand on cancer cells, allowing interaction of tumor cells with endothelium, leukocytes, and platelets. Here, we review the structural biology of CD44 and of HCELL, and present current data on the function of these molecules in mediating organ-specific homing/metastasis of CTCs.

CD43 expression is an adverse prognostic factor in diffuse large B-Cell lymphoma

BACKGROUND

CD43 is a transmembrane glycoprotein expressed in different hematopoietic cells, including some subsets of B lymphocytes. About a quarter of diffuse large B-cell lymphomas (DLBCLs) express CD43, but its prognostic significance is unknown.

PATIENTS AND METHODS

We analyzed the prognostic effect of immunohistochemically determined CD43 expression in 119 patients with newly diagnosed DLBCL. All were treated with CHOP (cyclophosphamide/doxorubicin/vincristine/prednisone)-like chemotherapy, 57 without and 62 with rituximab.

RESULTS

A total of 31 DLBCL cases (26%) expressed CD43. Patients with CD43+ and CD43- lymphomas did not differ regarding sex, International Prognostic Index (IPI) factors and score, rituximab treatment, presence of bulky disease, or germinal center subtype. Median follow-up was 45 months. Patients with CD43+ DLBCL had significantly lower complete response rates (59% vs. 80%; P = .019), 2-year event-free survival (EFS) rates (34% vs. 64%; P = .003), and overall survival (OS) rates (45% vs. 76%; P = .002). The prognostic significance of CD43 expression was retained in multivariate analysis (relative risk [RR] 2.04; P = .013 for EFS; RR 2.17; P = .016 for OS). In subgroup analysis, the effect of CD43 expression was significant in patients treated with rituximab and those with low IPI, whereas it was not reached in patients treated without rituximab. The effect was not observed in patients with high IPI.

CONCLUSION

These results indicate that CD43 expression is an important independent adverse prognostic factor in DLBCL.