Opposing roles for CD34 in B16 melanoma tumor growth alter early stage vasculature and late stage immune cell infiltration

VEGFR-Mediated Cytotoxic Activity of Pulicaria undulata Isolated Metabolites: A Biological Evaluation and In Silico Study

Natural products play a remarkable role not only in the synthesis, design, and discovery of new drugs but also as the most prominent source of drugs and bioactive substances. Adding to the search for new sources of safe innovative antitumor drugs, here we reported a phytochemical study on Pulicaria undulata which revealed promising antiangiogenic agents. Six compounds were isolated and identified as xanthoxyline (1), stigmasterol (2), oleanolic acid (3), salvigenin (4), rhamnetin (5) and dihydroquercetin-4′-methyl ether (6) using nuclear magnetic resonance (NMR) spectroscopic techniques. Compound 3 and 4 are first reported in Pulicaria genus. Both the extract and isolated compounds were evaluated for in vitro antiproliferative activity against breast cancer cell line (MCF-7). In vivo antiproliferative activity against Ehrlich’s ascites carcinoma (EAC) were also assessed. The P. undulata extract and isolates showed significant reduction in tumor weight, decreased both serum vascular endothelial growth factor B (VEGF-B) levels and vascular endothelial growth factor receptor 2 (VEGFR-2) expression significantly compared to the control EAC group, suggesting an antiangiogenic activity through the inhibition of VEGF signaling. Besides, they displayed reduction in CD34 expression, confirming their antiangiogenic effect. Moreover, the potential affinity of isolated compounds to human estrogen nuclear receptor-alpha (hER-α), the most recognized modulator of VEGFR-2 expression, was virtually estimated through molecular modeling studies. The most promising activity profiles were assigned to the investigated flavonoids, compounds 4–6, as well as the alkyl-phenylketone, compound 1. Additionally, these four top active compounds showed respective high to intermediate docking scores while possessing preferential binding with hER-α critical pocket residues. Based on the provided data, these isolated compounds illustrated promising inhibitors of VEGF-stimulated angiogenesis, which could be a possible mechanism for their anticancer activity.

p90RSK-MAGI1 Module Controls Endothelial Permeability by Post-translational Modifications of MAGI1 and Hippo Pathway

Previously, we reported that post-translational modifications (PTMs) of MAGI1, including S741 phosphorylation and K931 de-SUMOylation, both of which are regulated by p90RSK activation, lead to endothelial cell (EC) activation. However, roles for p90RSK and MAGI1-PTMs in regulating EC permeability remain unclear despite MAGI1 being a junctional molecule. Here, we show that thrombin (Thb)-induced EC permeability, detected by the electric cell-substrate impedance sensing (ECIS) based system, was decreased by overexpression of dominant negative p90RSK or a MAGI1-S741A phosphorylation mutant, but was accelerated by overexpression of p90RSK, siRNA-mediated knockdown of magi1, or the MAGI1-K931R SUMOylation mutant. MAGI1 depletion also increased the mRNA and protein expression of the large tumor suppressor kinases 1 and 2 (LATS1/2), which inhibited YAP/TAZ activity and increased EC permeability. Because the endothelial barrier is a critical mediator of tumor hypoxia, we also evaluated the role of p90RSK activation in tumor vessel leakiness by using a relatively low dose of the p90RSK specific inhibitor, FMK-MEA. FMK-MEA significantly inhibited tumor vessel leakiness at a dose that does not affect morphology and growth of tumor vessels in vivo. These results provide novel insights into crucial roles for p90RSK-mediated MAGI1 PTMs and the Hippo pathway in EC permeability, as well as p90RSK activation in tumor vessel leakiness.

A sticky wicket: Defining molecular functions for CD34 in hematopoietic cells

The CD34 cell surface antigen is widely expressed in tissues on cells with progenitor-like properties and on mature vascular endothelia. In adult human bone marrow, CD34 marks hematopoietic stem and progenitor cells (HSPCs) starting from the bulk of hematopoietic stem cells with long-term repopulating potential (LT-HSCs) throughout expansion and differentiation of oligopotent and unipotent progenitors. CD34 protein surface expression is typically lost as cells mature into terminal effectors. Because of this expression pattern of HSPCs, CD34 has had a central role in the evaluation or selection of donor graft tissue in HSC transplant (HSCT). Given its clinical importance, it is surprising that the biological functions of CD34 are still poorly understood. This enigma is due, in part, to CD34's context-specific role as both a pro-adhesive and anti-adhesive molecule and its potential functional redundancy with other sialomucins. Moreover, there are also critical differences in the regulation of CD34 expression on HSPCs in humans and experimental mice. In this review, we highlight some of the more well-defined functions of CD34 in HSPCs with a focus on proposed functions most relevant to HSCT biology.

Short- and long-term impact of hyperoxia on the blood and retinal cells' transcriptome in a mouse model of oxygen-induced retinopathy

BACKGROUND

We aimed to identify global blood and retinal gene expression patterns in murine oxygen-induced retinopathy (OIR), a common model of retinopathy of prematurity, which may allow better understanding of the pathogenesis of this severe ocular prematurity complication and identification of potential blood biomarkers.

METHODS

A total of 120 C57BL/6J mice were randomly divided into an OIR group, in which 7-day-old pups were maintained in 75% oxygen for 5 days, or a control group. RNA was extracted from the whole-blood mononuclear cells and retinal cells on days 12, 17, and 28. Gene expression in the RNA samples was evaluated with mouse gene expression microarrays.

RESULTS

There were 38, 1370 and 111 genes, the expression of which differed between the OIR and control retinas on days 12, 17, and 28, respectively. Gene expression in the blood mononuclear cells was significantly altered only on day 17. Deptor and Nol4 genes showed reduced expression both in the blood and retinal cells on day 17.

CONCLUSION

There are sustained marked changes in the global pattern of gene expression in the OIR mice retinas. An altered expression of Deptor and Nol4 genes in the blood mononuclear cells requires further investigation as they may indicate retinal neovascularization.

Loss of Vascular CD34 Results in Increased Sensitivity to Lung Injury

Survival during lung injury requires a coordinated program of damage limitation and rapid repair. CD34 is a cell surface sialomucin expressed by epithelial, vascular, and stromal cells that promotes cell adhesion, coordinates inflammatory cell recruitment, and drives angiogenesis. To test whether CD34 also orchestrates pulmonary damage and repair, we induced acute lung injury in wild-type (WT) and Cd34^-/- mice by bleomycin administration. We found that Cd34^-/- mice displayed severe weight loss and early mortality compared with WT controls. Despite equivalent early airway inflammation to WT mice, CD34-deficient animals developed interstitial edema and endothelial delamination, suggesting impaired endothelial function. Chimeric Cd34^-/- mice reconstituted with WT hematopoietic cells exhibited early mortality compared with WT mice reconstituted with Cd34^-/- cells, supporting an endothelial defect. CD34-deficient mice were also more sensitive to lung damage caused by influenza infection, showing greater weight loss and more extensive pulmonary remodeling. Together, our data suggest that CD34 plays an essential role in maintaining vascular integrity in the lung in response to chemical- and infection-induced tissue damage.

Interleukin 8 serum concentration, but not lactate dehydrogenase activity, positively correlates to CD34 antigen in melanoma tumors

CD34 promotes melanoma cell motility, negative regulation of cellular response to hypoxia and positive regulation of vasculogenesis. Interleukin 8 (IL-8) is responsible for angiogenic response in endothelial cells, increases proliferation, metastasis, and survival of melanoma cells. The aim of our study was evaluation of relationship between CD34 immunoexpression and IL-8 serum concentrations in melanoma patients. The study was conducted on patients with melanoma that were divided in: Clark II (17 patients - 19.3%), Clark III (33 patients - 37.5%), Clark IV (22 patients - 25%), and Clark V (16 patients - 18.2%) levels. CD34 expression was absent for Clark II melanomas, and positive for Clark III (6.1%), Clark IV (40.9%), and Clark V (56.2%). The CD34 immune-mark was highly positive only for Clark IV and V levels. Interleukin 8 (IL-8) had high values (above 15 pg/mL) for all patients with melanoma (58.9% - Clark II; 87.8% - Clark III; 90.9% - Clark IV and 93.7% - Clark V). We have found a strong and statistically significant correlation between CD34 and IL-8 for Clark IV (r = 0.54, P < 0.05) and Clark V (r = 0.72, P < 0.05) melanomas. CD34 and IL-8 are associated with poor prognosis of melanoma, metastasis, and neoangiogenesis.

De novo protein sequencing, humanization and in vitro effects of an antihuman CD34 mouse monoclonal antibody

QBEND/10 is a mouse immunoglobulin lambda-chain monoclonal antibody with strict specificity against human hematopoietic progenitor cell antigen CD34. Our in vitro study showed that QBEND/10 impairs the tube formation of human umbilical vein endothelial cells (HUVECs), suggesting that the antibody may be of potential benefit in blocking tumor angiogenesis. We provided a de novo protein sequencing method through tandem mass spectrometry to identify the amino acid sequences in the variable heavy and light chains of QBEND/10. To reduce immunogenicity for clinical applications, QBEND/10 was further humanized using the resurfacing approach. We demonstrate that the de novo sequenced and humanized QBEND/10 retains the biological functions of the parental mouse counterpart, including the binding kinetics to CD34 and blockage of the tube formation of the HUVECs.

CD34 Promotes Pathological Epi-Retinal Neovascularization in a Mouse Model of Oxygen-Induced Retinopathy

The sialomucins CD34 and podocalyxin (PODXL) are anti-adhesive molecules expressed at the luminal membrane of endothelial cells of small blood vessels and facilitate vascular lumen formation in the developing mouse aorta. CD34 transcript and protein levels are increased during human angiogenesis, its expression is particularly enriched on endothelial tip cell filopodia and CD34 is a marker for tip cells in vitro. Here, we investigated whether CD34 merely marks endothelial tip cells or has a functional role in tip cells and angiogenesis. We assessed that silencing CD34 in human microvascular endothelial cells has little effect on endothelial cell migration or invasion, but has a significant effect on vascular-endothelial growth factor-induced angiogenic sprouting activity in vitro. In vivo, the absence of CD34 reduced the density of filopodia on retinal endothelial tip cells in neonatal mice, but did not influence the overall architecture of the retinal vascular network. In oxygen-induced retinopathy, Cd34^-/- mice showed normal intra-retinal regenerative angiogenesis but the number of pathological epi-retinal neovascular tufts were reduced. We conclude that CD34 is not essential for developmental vascularization in the retina, but its expression promotes the formation of pathological, invasive vessels during neovascularization.

Introducing Cytology-Based Theranostics in Oral Squamous Cell Carcinoma: A Pilot Program

We aimed to evaluate the feasibility and reliability of brush cytology in the biomarker expression profiling of oral squamous cell carcinomas within the concept of theranostics, and to correlate this biomarker profile with patient measurable outcomes. Markers representative of prognostic gene expression changes in oral squamous cell carcinoma was selected. These markers were also selected to involve pathways for which commercially available or investigational agents exist for clinical application. A set of 7 markers were analysed by immunocytochemistry on the archival primary tumour material of 99 oral squamous cell carcinoma patients. We confirmed the feasibility of the technique for the expression profiling of oral squamous cell carcinomas. Furthermore, our results affirm the prognostic significance of the epidermal growth factor receptor (EGFR) family and the angiogenic pathway in oral squamous cell carcinoma, confirming their interest for targeted therapy. Brush cytology appears feasible and applicable for the expression profiling of oral squamous cell carcinoma within the concept of theranostics, according to sample availability.

Immunoglobulin free light chains are biomarkers of poor prognosis in basal-like breast cancer and are potential targets in tumor-associated inflammation

Inflammation is an important component of various cancers and its inflammatory cells and mediators have been shown to have prognostic potential. Tumor-infiltrating mast cells can promote tumor growth and angiogenesis, but the mechanism of mast cell activation is unclear. In earlier studies, we demonstrated that immunoglobulin free light chains (FLC) can trigger mast cells in an antigen-specific manner. Increased expression of FLC was observed within stroma of various human cancers including those of breast, colon, lung, pancreas, kidney and skin, and FLC expression co-localized with areas of mast cell infiltration. In a large cohort of breast cancer patients, FLC expression was shown associated with basal-like cancers with an aggressive phenotype. Moreover, lambda FLC was found expressed in areas of inflammatory infiltration and its expression was significantly associated with poor clinical outcome. Functional importance of FLCs was shown in a murine B16F10 melanoma model, where inhibition of FLC-mediated mast cell activation strongly reduced tumor growth. Collectively, this study identifies FLCs as a ligand in the pro-tumorigenic activation of mast cells. Blocking this pathway may open new avenues for the inhibition of tumor growth, while immunohistochemical staining of FLC may be helpful in the diagnosis and prognosis of cancer.

Podocalyxin regulates murine lung vascular permeability by altering endothelial cell adhesion

Despite the widespread use of CD34-family sialomucins (CD34, podocalyxin and endoglycan) as vascular endothelial cell markers, there is remarkably little known of their vascular function. Podocalyxin (gene name Podxl), in particular, has been difficult to study in adult vasculature as germ-line deletion of podocalyxin in mice leads to kidney malformations and perinatal death. We generated mice that conditionally delete podocalyxin in vascular endothelial cells (Podxl(ΔEC) mice) to study the homeostatic role of podocalyxin in adult mouse vessels. Although Podxl(ΔEC) adult mice are viable, their lungs display increased lung volume and changes to the matrix composition. Intriguingly, this was associated with increased basal and inflammation-induced pulmonary vascular permeability. To further investigate the etiology of these defects, we isolated mouse pulmonary endothelial cells. Podxl(ΔEC) endothelial cells display mildly enhanced static adhesion to fibronectin but spread normally when plated on fibronectin-coated transwells. In contrast, Podxl(ΔEC) endothelial cells exhibit a severely impaired ability to spread on laminin and, to a lesser extent, collagen I coated transwells. The data suggest that, in endothelial cells, podocalyxin plays a previously unrecognized role in maintaining vascular integrity, likely through orchestrating interactions with extracellular matrix components and basement membranes, and that this influences downstream epithelial architecture.

Adhesion molecule expression and function of primary endothelial cells in benign and malignant tissues correlates with proliferation

Background

Comparative analysis of the cellular biology of the microvasculature in different tissues requires the availability of viable primary endothelial cells (ECs). This study describes a novel method to isolate primary ECs from healthy organs, repair blastemas and tumors as examples of non-proliferating and proliferating benign and malignant tissues and their functional characterization.

Methodology/Principal Findings

Single cell suspensions from hearts, lungs, repair blastemas and tumors were incubated consecutively with an anti-CD31 antibody and magnetic micro-beads, coupled to a derivative of biotin and streptavidin, respectively. Following magnetic bead separation, CD31-positive ECs were released by biotin-streptavidin competition. In the absence of micro-beads, ECs became adherent to plastic surfaces. ECs from proliferating repair blastemas and tumors were larger and exhibited higher expression densities of CD31, CD105 and CD102 compared to those from non-proliferating normal tissues such as heart and lung. The expression density of CD34 was particularly high in tumor-derived ECs, and that of CD54 and CD144 in ECs of repair blastemas. Functionally, ECs of non-proliferating and proliferating tissues differed in their capacity to form tubes in matrigel and to align under flow conditions.

Conclusions/Significance

This method provides a powerful tool to generate high yields of viable, primary ECs of different origins. The results suggest that an altered expression of adhesion molecules on ECs in proliferating tissues contribute to loss of EC function that might cause a chaotic tumor vasculature.

SAP domain-dependent Mkl1 signaling stimulates proliferation and cell migration by induction of a distinct gene set indicative of poor prognosis in breast cancer patients

Background

The main cause of death of breast cancer patients is not the primary tumor itself but the metastatic disease. Identifying breast cancer-specific signatures for metastasis and learning more about the nature of the genes involved in the metastatic process would 1) improve our understanding of the mechanisms of cancer progression and 2) reveal new therapeutic targets. Previous studies showed that the transcriptional regulator megakaryoblastic leukemia-1 (Mkl1) induces tenascin-C expression in normal and transformed mammary epithelial cells. Tenascin-C is known to be expressed in metastatic niches, is highly induced in cancer stroma and promotes breast cancer metastasis to the lung.

Methods

Using HC11 mammary epithelial cells overexpressing different Mkl1 constructs, we devised a subtractive transcript profiling screen to identify the mechanism by which Mkl1 induces a gene set co-regulated with tenascin-C. We performed computational analysis of the Mkl1 target genes and used cell biological experiments to confirm the effect of these gene products on cell behavior. To analyze whether this gene set is prognostic of accelerated cancer progression in human patients, we used the bioinformatics tool GOBO that allowed us to investigate a large breast tumor data set linked to patient data.

Results

We discovered a breast cancer-specific set of genes including tenascin-C, which is regulated by Mkl1 in a SAP domain-dependent, serum response factor-independent manner and is strongly implicated in cell proliferation, cell motility and cancer. Downregulation of this set of transcripts by overexpression of Mkl1 lacking the SAP domain inhibited cell growth and cell migration. Many of these genes are direct Mkl1 targets since their promoter-reporter constructs were induced by Mkl1 in a SAP domain-dependent manner. Transcripts, most strongly reduced in the absence of the SAP domain were mechanoresponsive. Finally, expression of this gene set is associated with high-proliferative poor-outcome classes in human breast cancer and a strongly reduced survival rate for patients independent of tumor grade.

Conclusions

This study highlights a crucial role for the transcriptional regulator Mkl1 and its SAP domain during breast cancer progression. We identified a novel gene set that correlates with bad prognosis and thus may help in deciding the rigor of therapy.

Immunohistochemical investigation of the angiogenic proteins VEGF, HIF-1α and CD34 in invasive ductal carcinoma of the breast

The expression of prognostic markers in cancer has become important in diagnostic routine and research. A high mitotic rate compromises the individual cell access to oxygen and nutrients, due to reduced blood supply. Cells undertake adaptive measures such as vascular endothelial growth factor (VEGF), expressed under the control of hypoxia-inducible factor-1α (HIF-1α). CD34 is an endothelial marker which can show the presence and distribution of blood vessels. This study evaluated the presence and relative expression of VEGF, HIF-1α and CD34 using immunohistochemistry of 60 breast tumors and double staining, correlating the findings with clinical and pathological variables. High VEGF expression was correlated with low cell proliferation, lymph node-negative, smaller tumor size and patients not receiving hormone therapy. High HIF-1α expression predominated in younger (<50-year) patients, subjected to neo-adjuvant therapy and in p53-negative tumors. Absence of metastasis, radiotherapy or hormone treatment, and estrogen receptor (ER)-positive tumors showed high CD34 immunoreactivity. We suggest that the angiogenic factors VEGF, HIF-1α and CD34 are important in breast cancer progression and their abundance in breast tumors has prognostic and predictive value.

Loss of SMAD4 from colorectal cancer cells promotes CCL15 expression to recruit CCR1+ myeloid cells and facilitate liver metastasis

BACKGROUND & AIMS

Loss of the tumor suppressor SMAD4 correlates with progression of colorectal cancer (CRC). In mice, colon tumors that express CCL9 recruit CCR1(+) myeloid cells, which facilitate tumor invasion and metastasis by secreting matrix metalloproteinase 9.

METHODS

We used human CRC cell lines to investigate the ability of SMAD4 to regulate expression of CCL15, a human ortholog of mouse CCL9. We used immunohistochemistry to compare levels of CCL15 and other proteins in 141 samples of human liver metastases.

RESULTS

In human CRC cell lines, knockdown of SMAD4 increased CCL15 expression, and overexpression of SMAD4 decreased it. SMAD4 bound directly to the promoter region of the CCL15 gene to negatively regulate its expression; transforming growth factor-β increased binding of SMAD4 to the CCL15 promoter and transcriptional repression. In livers of nude mice, SMAD4-deficient human CRC cells up-regulated CCL15 to recruit CCR1(+) cells and promote metastasis. In human tumor samples, there was a strong inverse correlation between levels of CCL15 and SMAD4; metastases that expressed CCL15 contained 3-fold more CCR1(+) cells than those without CCL15. Patients with CCL15-expressing metastases had significantly shorter times of disease-free survival than those with CCL15-negative metastases. CCR1(+) cells in the metastases expressed the myeloid cell markers CD11b and myeloperoxidase, and also matrix metalloproteinase 9.

CONCLUSIONS

In human CRC cells, loss of SMAD4 leads to up-regulation of CCL15 expression. Human liver metastases that express CCL15 contain higher numbers CCR1(+) cells; patients with these metastases have shorter times of disease-free survival. Reagents designed to block CCL15 recruitment of CCR1(+) cells could prevent metastasis of CRC to liver.

The critical role of mast cell-derived hypoxia-inducible factor-1α in human and mice melanoma growth

Mast cells play an important role in tumorigenesis. Histamine released from mast cells stimulates new vessel formation by acting through the histamine1 (H1) receptor. Despite the evidence of the role of mast cells in tumor growth and angiogenesis, the potential mechanism remains to be elucidated. Therefore, we investigated the role of mast cell-derived HIF-1α in melanoma growth. Here, we identify that the most positive cells for HIF-1α staining are seen in mast cells of human and animal melanoma tissue. The number of the stromal cell types (fibroblasts, macrophages and endothelial cells) was also increased in melanoma tissues. In activated bone marrow-derived mast cells (BMMCs), expressions of HIF-1α and VEGF were increased. Histamine also induced the expressions of HIF-1α and VEGF in BMMCs. H1 receptor antagonists significantly improved overall survival rates and substantially suppressed tumor growth as well as the infiltration of mast cells and levels of VEGF through the inhibition of HIF-1α expression in B16F10 melanoma-bearing mice. Furthermore, the injection of HIF-1α depleted BMMCs markedly inhibited the growth of tumors and migration of mast cells and increased the survival rate of the mice. These findings emphasize that the growth of melanoma can actually be exacerbated by mast cell-derived HIF-1α. In aggregate, our results reveal a novel role for mast cell-derived HIF-1α in the melanoma microenvironment and have important implications for the design of therapeutic strategies.

IL-7Rα and L-selectin, but not CD103 or CD34, are required for murine peanut-induced anaphylaxis

Background

Allergy to peanuts results in severe anaphylactic responses in affected individuals, and has dramatic effects on society and public policy. Despite the health impacts of peanut-induced anaphylaxis (PIA), relatively little is known about immune mechanisms underlying the disease. Using a mouse model of PIA, we evaluated mice with deletions in four distinct immune molecules (IL7Rα, L-selectin, CD34, CD103), for perturbed responses.

Methods

PIA was induced by intragastric sensitization with peanut antigen and cholera toxin adjuvant, followed by intraperitoneal challenge with crude peanut extract (CPE). Disease outcome was assessed by monitoring body temperature, clinical symptoms, and serum histamine levels. Resistant mice were evaluated for total and antigen specific serum IgE, as well as susceptibility to passive systemic anaphylaxis.

Results

PIA responses were dramatically reduced in IL7Rα^−/− and L-selectin^−/− mice, despite normal peanut-specific IgE production and susceptibility to passive systemic anaphylaxis. In contrast, CD34^−/− and CD103^−/− mice exhibited robust PIA responses, indistinguishable from wild type controls.

Conclusions

Loss of L-selectin or IL7Rα function is sufficient to impair PIA, while CD34 or CD103 ablation has no effect on disease severity. More broadly, our findings suggest that future food allergy interventions should focus on disrupting sensitization to food allergens and limiting antigen-specific late-phase responses. Conversely, therapies targeting immune cell migration following antigen challenge are unlikely to have significant benefits, particularly considering the rapid kinetics of PIA.