Expression of a novel endothelial marker, C-type lectin 14A, in epithelial ovarian cancer and its prognostic significance

A glimpse into the past: phylogenesis and protein domain analysis of the group XIV of C-type lectins in vertebrates

Background

The group XIV of C-type lectin domain-containing proteins (CTLDcps) is one of the seventeen groups of CTLDcps discovered in mammals and composed by four members: CD93, Clec14A, CD248 and Thrombomodulin, which have shown to be important players in cancer and vascular biology. Although these proteins belong to the same family, their phylogenetic relationship has never been dissected. To resolve their evolution and characterize their protein domain composition we investigated CTLDcp genes in gnathostomes and cyclostomes and, by means of phylogenetic approaches as well as synteny analyses, we inferred an evolutionary scheme that attempts to unravel their evolution in modern vertebrates.

Results

Here, we evidenced the paralogy of the group XIV of CTLDcps in gnathostomes and discovered that a gene loss of CD248 and Clec14A occurred in different vertebrate groups, with CD248 being lost due to chromosome disruption in birds, while Clec14A loss in monotremes and marsupials did not involve chromosome rearrangements. Moreover, employing genome annotations of different lampreys as well as one hagfish species, we investigated the origin and evolution of modern group XIV of CTLDcps. Furthermore, we carefully retrieved and annotated gnathostome CTLDcp domains, pointed out important differences in domain composition between gnathostome classes, and assessed codon substitution rate of each domain by analyzing nonsynonymous (Ka) over synonymous (Ks) substitutions using one representative species per gnathostome order.

Conclusions

CTLDcps appeared with the advent of early vertebrates after a whole genome duplication followed by a sporadic tandem duplication. These duplication events gave rise to three CTLDcps in the ancestral vertebrate that underwent further duplications caused by the independent polyploidizations that characterized the evolution of cyclostomes and gnathostomes. Importantly, our analyses of CTLDcps in gnathostomes revealed critical inter-class differences in both extracellular and intracellular domains, which might help the interpretation of experimental results and the understanding of differences between animal models.

LASP-1 interacts with ErbB2 in ovarian cancer cells

LASP-1 was identified as a protein following mass spectrometric analysis of phosphoproteins consequent to signaling by ErbB2 in SKOV-3 cells. It has been previously identified as an oncogene and is located on chromosomal arm 17q 0.76Mb centromeric to ErbB2. It is expressed in serous ovarian cancer cell lines as a 40kDa protein. In SKOV-3 cells, it was phosphorylated and was inhibited by Lapatinib and CP7274714. LASP-1 co-immunoprecipitated with ErbB2 in SKOV-3 cells, suggesting a direct interaction. This interaction and phosphorylation were independent of the kinase activity of ErbB2. Moreover, the binding of LASP-1 to ErbB2 was independent of the  tyrosine phosphorylation of LASP-1. LASP-1 was neither expressed on the surface epithelium of the normal ovary nor in the fallopian tube. It was expressed in 28% of ovarian tumours (n=101) that did not significantly correlate with other clinical factors. In tumours from patients with invasive ductal carcinoma of the breast who had ErbB2 amplification (3+), LASP-1 was expressed in 3/20 (p <0.001). Analysis of the expression of an independent dataset of ovarian and breast tumors from TCGA showed the significant co-occurrence of ErbB2 and LASP-1 (p<0.01). These results suggest that LASP-1 and ErbB2 interaction could be important in the pathogenesis of ovarian cancer.

CLEC14A protects against podocyte injury in mice with adriamycin nephropathy

Podocyte injury is a major determinant of focal segmental glomerular sclerosis (FSGS) and the identification of potential therapeutic targets for preventing podocyte injury has clinical importance for the treatment of FSGS. CLEC14A is a single-pass transmembrane glycoprotein belonging to the vascular expressed C-type lectin family. CLEC14A is found to be expressed in vascular endothelial cells during embryogenesis and is also implicated in tumor angiogenesis. However, the current understanding of the biological functions of CLEC14A in podocyte is very limited. In this study, we found that CLEC14A was expressed in podocyte and protected against podocyte injury in mice with Adriamycin (ADR)-induced FSGS. First, we observed that CLEC14A was downregulated in mice with ADR nephropathy and renal biopsies from individuals with FSGS and other forms of podocytopathies. Moreover, CLEC14A deficiency exacerbated podocyte injury and proteinuria in mice with ADR nephropathy accompanied by enhanced inflammatory cell infiltration and inflammatory responses. In vitro, overexpression of CLEC14A in podocyte had pleiotropic protective actions, including anti-inflammatory and anti-apoptosis effects. Mechanistically, CLEC14A inhibited high-mobility group box 1 protein (HMGB1) release, at least in part by directly binding HMGB1, and suppressed HMGB1-mediated signaling, including NF-κB signaling and early growth response protein 1 (EGR1) signaling. Taken together, our findings provide new insights into the pivotal role of CLEC14A in maintaining podocyte function, indicating that CLEC14A may be an innovative therapeutic target in FSGS.

Expression of cancer stem cell markers CD24, EPHA1 and CD9 and their correlation with clinical outcome in epithelial ovarian tumours

BACKGROUND

There has been variability between laboratories in the identification of cancer stem cells (CSCs) markers for epithelial ovarian cancer (EOC). We have evaluated three new surface markers for EOC to identify CSCs precisely.

METHODS

Three new putative CSCs specific surface markers CD9, CD24 and EPHA1 identified by a bioinformatics approach were evaluated in normal ovary, fallopian tube and ovarian tumours.

RESULTS

The expression of CD9 alone was observed in normal ovarian surface epithelium and fallopian tube whereas CD24 and EPHA1 were not expressed (n= 5). CD24 was expressed in all tumours (N= 101) while CD9 and EPHA1 were expressed in 89 and 71 tumours, respectively. The statistical analysis showed significant correlation of the stage of the disease (p< 0.0001), type of surgery (p< 0.0001) and residual disease (p< 0.0001) with overall survival. Although expression of CD9, CD24 and EPHA1 was observed in the majority of tumours there was no significant correlation with outcome. In patients who underwent primary surgery, increased expression of CD24 significantly correlated with poor survival. The expression of CD24 was significantly reduced (p< 0.002) upon analysis of paired sections from patients prior to surgery and at interval debulking surgery (n= 16).

CONCLUSION

These findings suggest that overexpression of these new markers may be useful in identifying and targeting ovarian CSCs and CD24 may be a putative CSCs marker in ovarian cancer.

The hedgehog pathway regulates cancer stem cells in serous adenocarcinoma of the ovary

PURPOSE

Signaling by cancer stem cells (CSCs) is known to occur at least in part through conserved developmental pathways. Here, the role of one of these pathways, i.e., the hedgehog pathway, was evaluated in high-grade serous ovarian carcinoma (HGSOC).

METHODS AND RESULTS

We found that in HGSOC, hedgehog inhibitors (HHIs) GANT61, LDE225 and GDC0449 reduced or inhibited the formation of spheroids enriched in CSCs. Primary malignant cells (PMCs) in ascites from HGSOC patients cultured in the presence of HHIs showed significant reduction in CSCs. Sonic hedgehog (SHH) significantly increased the expression of ALDH1A1, which was inhibited by GANT61. In the presence of a SHH neutralizing antibody (5E1), a significant reduction in the number of spheroids was observed in HGSOC-derived cell lines. Further, the motility, migration and clonogenic growth of the cells were significantly reduced by HHIs. In the presence of GANT61, a reduction of cells from PMCs in the G0 phase of the cell cycle was observed. The magnitude of difference in expression of Gli1 in tumors from the same HGSOC patients at presentation and at interval debulking surgery was greater in patients who had a recurrence on follow up. GANT61 also significantly inhibited the growth of CSCs in nude mice. Finally, RNA sequencing of HGSOC cells treated with GANT61 showed a significantly reduced expression of CSC markers.

CONCLUSIONS

Our results indicate that the hedgehog pathway plays an important role in maintaining the integrity of CSCs in HGSOC and could be a potential therapeutic target.

ALDH1A1+ ovarian cancer stem cells co-expressing surface markers CD24, EPHA1 and CD9 form tumours in vivo

One of the reasons for recurrence following treatment of high grade serous ovarian carcinoma (HGSOC) is the persistence of residual cancer stem cells (CSCs). There has been variability between laboratories in the identification of CSC markers for HGSOC. We have identified new surface markers (CD24, CD9 and EPHA1) in addition to those previously known (CD44, CD117 and CD133) using a bioinformatics approach. The expression of these surface markers was evaluated in ovarian cancer cell lines, primary malignant cells (PMCs), normal ovary and HGSOC. There was no preferential expression of any of the markers or a combination. All the markers were expressed at variable levels in ovarian cancer cell lines and PMCs. Only CD117 and CD9 were expressed in the normal ovarian surface epithelium and fallopian tube. Both ALDEFLUOR (ALDH1A1) and side population assays identified a small proportion of cells (<3%) separately that did not overlap with little variability in cell lines and PMCs. All surface markers were co-expressed in ALDH1A1+ cells without preference for one combination. The cell cycle analysis of ALDH1A1+ cells alone revealed that majority of them reside in G0/G1 phase of cell cycle. Further separation of G0 and G1 phases showed that ALDH1A1+ cells reside in G1 phase of the cell cycle. Xenograft assays showed that the combinations of ALDH1A1 + cells co-expressing CD9, CD24 or EPHA1 were more tumorigenic and aggressive with respect to ALDH1A1-cells. These data suggest that a combined approach could be more useful in identifying CSCs in HGSOC.

CLEC14A deficiency exacerbates neuronal loss by increasing blood-brain barrier permeability and inflammation

Background

Ischemic stroke is a main cause of mortality. Blood-brain barrier (BBB) breakdown appears to play a critical role in inflammation in patients with ischemic stroke and acceleration of brain injury. The BBB has a protective function and is composed of endothelial cells, pericytes, and astrocytes. In ischemic stroke treatments, regulation of vascular endothelial growth factor (VEGF)-A and vascular endothelial growth factor receptor (VEGFR)-2 is a crucial target despite adverse effects. Our previous study found that loss of C-type lectin family 14 member A (CLEC14A) activated VEGF-A/VEGFR-2 signaling in developmental and tumoral angiogenesis. Here, we evaluate the effects of BBB impairment caused by CLEC14A deficiency in ischemia-reperfusion injury.

Methods

In vitro fluorescein isothiocyanate (FITC)-dextran permeability, transendothelial electrical resistance (TEER) assay, and immunostaining were used to evaluate endothelial integrity. BBB permeability was assessed using Evans blue dye and FITC-dextran injection in Clec14a^−/− (CLEC14A-KO) mice and wild-type mice. Middle cerebral artery occlusion surgery and behavioral assessments were performed to evaluate the neurologic damage. The change of tight junctional proteins, adhesion molecules, pro-inflammatory cytokines, and microglial were confirmed by immunofluorescence staining, Western blotting, and quantitative reverse transcription polymerase chain reaction of brain samples.

Results

In endothelial cells, knockdown of CLEC14A increased FITC-dextran permeability and decreased transendothelial electrical resistance; the severity of this effect increased with VEGF treatment. Immunofluorescence staining revealed that tight junctional proteins were attenuated in the CLEC14A knockdown endothelial cells. Consistent with the in vitro results, CLEC14A-KO mice that were injected with Evans blue dye had cerebral vascular leakage at postnatal day 8; wild-type mice had no leakage. We used a middle cerebral artery occlusion model and found that CLEC14A-KO mice had severe infarcted brain and neurological deficits with upregulated VEGFR-2 expression. FITC-dextran leakage was present in CLEC14A-KO mice after ischemia-reperfusion, and the numbers of tight junctional molecules were significantly decreased. Loss of CLEC14A increased the pro-inflammatory response through adhesion molecule expression, and glial cells were activated.

Conclusions

These results suggest that activation of VEGFR-2 in CLEC14A-KO mice aggravates ischemic stroke by exacerbating cerebral vascular leakage and increasing neuronal inflammation after ischemia-reperfusion injury.

IL-17F expression correlates with clinicopathologic factors and biological markers in non-small cell lung cancer

Interleukin-17 F (IL-17F) is a pro-inflammatory cytokine that participate in inflammatory responses. Studies showed that IL-17F is likely involved in tumor development, but the biological function of IL-17F in non-small cell lung cancer (NSCLC) is unclear. The aim of this study was to explore the biological role of IL-17F in NSCLC and investigate its correlation with biological markers CD31, P53, Ki-67 and E-cadherin. Paraffin-embedded tumor tissues from 55 NSCLC patients were collected to detect proteins expression using immunohistochemistry (IHC). 12 normal lung tissues samples were used as control. IHC results showed that the expression of IL-17F in NSCLC cells (61.8%) was significantly higher compared with normal lung tissues (25.0%) (P <  0.05). The expression of IL-17F was positively associated with tumor differentiation and negatively associated with lymph node metastasis and TNM staging (P all < 0.05). Multivariate analysis showed that IL-17F expression was an independent factor associated with TNM staging (P <  0.01). Pearson's correlation analysis showed a negative correlation between IL-17F and CD31 expression and a positive correlation between IL-17F and E-cadherin expression (P all < 0.05). There was no relationship between IL-17 F and P53 or Ki-67 expression in NSCLC tissues (P >  0.05). These data suggest that IL-17 F may be considered as a potential marker for predicting the progression of NSCLC.

C-type lectin domain group 14 proteins in vascular biology, cancer and inflammation

The C‐type lectin domain (CTLD) group 14 family of transmembrane glycoproteins consist of thrombomodulin, CD93, CLEC14A and CD248 (endosialin or tumour endothelial marker‐1). These cell surface proteins exhibit similar ectodomain architecture and yet mediate a diverse range of cellular functions, including but not restricted to angiogenesis, inflammation and cell adhesion. Thrombomodulin, CD93 and CLEC14A can be expressed by endothelial cells, whereas CD248 is expressed by vasculature associated pericytes, activated fibroblasts and tumour cells among other cell types. In this article, we review the current literature of these family members including their expression profiles, interacting partners, as well as established and speculated functions. We focus primarily on their roles in the vasculature and inflammation as well as their contributions to tumour immunology. The CTLD group 14 family shares several characteristic features including their ability to be proteolytically cleaved and engagement of some shared extracellular matrix ligands. Each family member has strong links to tumour development and in particular CD93, CLEC14A and CD248 have been proposed as attractive candidate targets for cancer therapy.

Microvessel Density (MVD) in Locally Advanced Breast Cancer

Background: The aim of this study was to evaluate microvessel density (MVD) by expression of CD31 and CLEC14A in core biopsies from previously untreated patients with locally advanced breast cancer (LABC) and assess its prognostic significance. Methods: MVD was evaluated in core needle biopsies (n = 92), collected prior to any treatment, from patients who were diagnosed with locally advanced breast cancer (LABC). Immunohistochemistry for expression of CD31 and CLEC14A were performed on these tumours. The median duration of follow-up was 9.3 years. The effect of prognostic factors on disease free survival (DFS) and overall survival (OS) was assessed using a Log rank test and Cox regression model. Results: The clinical factors such as age, clinical nodal stage, stage and pathological nodal status were found to be significant in predicting overall survival by multivariate analysis (P<0.05). Out of 92, 52 tumours had blood vessels expressing CD31, whereas in the remainder, there was no expression. The mean and median MVD of CD31 in 92 tumours was 38 and 5.5 respectively, and it was not a significant factor for predicting disease free survival or overall survival. When we considered the tumours (n=52) which expressed CD31, patients who had very high MVD (>100), had inferior progression free survival and overall survival (P=0.5). There was no expression of CLEC14A in any of the core needle biopsies whereas it was expressed in specimens from mastectomy from the same patient. Conclusion: This is the first report of MVD in LABC prior to any treatment. The results suggest angiogenesis could be a prognostic factor in LABC.

A Review of Anti-Angiogenic Targets for Monoclonal Antibody Cancer Therapy

Tumor angiogenesis is a key event that governs tumor progression and metastasis. It is controlled by the complicated and coordinated actions of pro-angiogenic factors and their receptors that become upregulated during tumorigenesis. Over the past several decades, vascular endothelial growth factor (VEGF) signaling has been identified as a central axis in tumor angiogenesis. The remarkable advent of recombinant antibody technology has led to the development of bevacizumab, a humanized antibody that targets VEGF and is a leading clinical therapy to suppress tumor angiogenesis. However, despite the clinical efficacy of bevacizumab, its significant side effects and drug resistance have raised concerns necessitating the identification of novel drug targets and development of novel therapeutics to combat tumor angiogenesis. This review will highlight the role and relevance of VEGF and other potential therapeutic targets and their receptors in angiogenesis. Simultaneously, we will also cover the current status of monoclonal antibodies being developed to target these candidates for cancer therapy.