Prognostic significance of epidermal growth factor-like domain 7 in pancreatic cancer

Role of EGFL7 in human cancers: A review

EGFL7 is a proangiogenic factor. It has been widely described with having a vital role in tubulogenesis and regulation of angiogenesis, mainly during embryogenesis and organogenesis. It has been mainly associated with NOTCH pathway, but there are reports showing association with MAPK and integrin pathways. Given its association with angiogenesis and these other pathways, there are several studies associating EGFL7 with carcinogenesis. In fact, most of the studies have pointed to EGFL7 as an oncogene, and some of them suggest EGFL7 expression as a possible biomarker of prognosis or use for a patient's follow-up. Here, we review the molecular pathways which EGFL7 is associated and highlight several studies describing the role of EGFL7 in tumorigenesis, separated by tumor type. Besides its role on angiogenesis, EGFL7 may act in other pathways as oncogene, which makes it a possible biomarker and a candidate to targeted therapy.

EGF repeats of epidermal growth factor‑like domain 7 promote endothelial cell activation and tumor escape from the immune system

The tumor blood vessel endothelium forms a barrier that must be crossed by circulating immune cells in order for them to reach and kill cancer cells. Epidermal growth factor‑like domain 7 (Egfl7) represses this immune infiltration by lowering the expression levels of leukocyte adhesion receptors on the surface of endothelial cells. However, the protein domains involved in these properties are not completely understood. Egfl7 is structurally composed of the predicted EMI‑, EGF‑ and C‑terminal domains. The present study aimed to investigate the roles of these different domains in tumor development by designing retroviruses coding for deletion mutants and then infecting 4T1 breast cancer cell populations, which consequently overexpressed the variants. By performing in vitro soft‑agar assays, it was found that Egfl7 and its deletion variants did not affect cell proliferation or anchorage‑independent growth. When 4T1 cells expressing either the wild‑type Egfl7 protein or Egfl7 domain variants were implanted in mice, Egfl7 expression markedly promoted tumor development and deletion of the EGF repeats decreased the tumor growth rate. By contrast, deleting any other domain displayed no significant effect on tumor development. The overexpression of Egfl7 also decreased T cell and natural killer cell infiltration in tumors, as determined by immunofluorescence staining of tumor sections, whereas deletion of the EGF repeats inhibited this effect. Reverse transcription‑quantitative PCR analysis of the mechanisms involved revealed that deleting the EGF repeats partially restored the expression levels of vascular cell adhesion molecule 1 and E‑selectin, which were suppressed by overexpression of Egfl7 in endothelial cells in vitro. This resulted in a higher number of lymphocytes bound to HUVEC expressing Egfl7‑ΔEGF compared with HUVEC expressing wild‑type Egfl7, as assessed by fluorescent‑THP‑1 adhesion assays onto endothelial cells. Overall, the present study demonstrated that the EGF repeats may participate in the protumoral and anti‑inflammatory effects of Egfl7.

Angiocrine endothelium: from physiology to cancer

The concept of cancer as a cell-autonomous disease has been challenged by the wealth of knowledge gathered in the past decades on the importance of tumor microenvironment (TM) in cancer progression and metastasis. The significance of endothelial cells (ECs) in this scenario was initially attributed to their role in vasculogenesis and angiogenesis that is critical for tumor initiation and growth. Nevertheless, the identification of endothelial-derived angiocrine factors illustrated an alternative non-angiogenic function of ECs contributing to both physiological and pathological tissue development. Gene expression profiling studies have demonstrated distinctive expression patterns in tumor-associated endothelial cells that imply a bilateral crosstalk between tumor and its endothelium. Recently, some of the molecular determinants of this reciprocal interaction have been identified which are considered as potential targets for developing novel anti-angiocrine therapeutic strategies.

High EGFL7 expression may predict poor prognosis in acute myeloid leukemia patients undergoing allogeneic hematopoietic stem cell transplantation

Epithelial growth factor-like 7 (EGFL7) is a secretory protein with a well-characterized role in angiogenesis and the oncogenesis of certain solid tumors. Overexpression of EGFL7 is associated with adverse prognosis in patients with cytogenetically normal acute myeloid leukemia (CN-AML). However, whether this association persists after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains unclear. To further clarify the prognostic role of EGFL7, seventy-one AML patients with EGFL7 expression data who underwent allo-HSCT from The Cancer Genome Atlas database were included and divided into either EGFL7^high or EGFL7^low group based on the median EGFL7 expression level. Two groups had similar clinical and molecular characteristics except that the EGFL7^high group had less frequent NPM1 mutations (P= .001). Kaplan-Meier survival curves showed that high EGFL7 expressers had shorter OS than the low expressers (P= .040). Univariate analysis showed that high EGFL7 expression, MLL-PTD, RUNX1 and TP53 mutations were associated with short OS (all P< .05). Multivariate analysis indicated that high EGFL7 expression, FLT3-ITD, RUNX1 and TP53 mutations were independent risk factors for OS (all P< .05). Collectively, our study suggested that EGFL7, like the other widely-used risk stratification factors, could serve as a prognostic tool and therapeutic target in AML, even after allo-HCST.

The Immunohistochemical Expression MTA 1 Protein and its Prognostic Value in Pancreatic Cancer

Purpose/aim: To examine with immunohistochemical assay MTA1 protein expression levels in pancreatic cancer tissues defining its prognostic value.

MATERIAL AND METHODS

The specimens derived from 51 patients who underwent surgery. The levels of MTA1 protein were compared with the age of the patients, their survival, and prognosis. Also, we studied clinical and histopathological factors such as the degree of tumor differentiation and its stage in correlation with MTA1 protein levels. In parallel, there was correlation between the expression of the ΜΤΑ1 protein and the aforementioned factors regarding survival rate. Furthermore, we independently correlated the patient's survival in relation to whether they had undergone adjuvant chemotherapy or not.

RESULTS

It has been found to be low, moderate, or high expression of MTA1 levels in 48 out of 51 cancer tissues. Specifically, 49.0% of patients had low expression, 33.3% moderate, and 11.8% high expression of MTA1. Regarding the expression of MTA1 protein in correlation with various clinical and histopathological factors, a statistically significant correlation was observed with the degree of differentiation (p = 0.0068) and with the stage of the disease (p = 0.0173), but not with survival (p = 0.0740) or the age of them (p = 0.1547). Finally, it was found that overexpression of the MTA1protein is a prognostic factor for shorter survival in patients with pancreatic cancer (average 4.67 ± 0.95 months).

CONCLUSIONS

MTA 1 protein may constitute an important prognostic marker in pancreatic cancer and could improve prognosis and treatment.

Viral nanoparticles decorated with novel EGFL7 ligands enable intravital imaging of tumor neovasculature

Angiogenesis is a dynamic process fundamental to the development of solid tumors. Epidermal growth factor-like domain 7 (EGFL7) is a protein whose expression is restricted to endothelial cells undergoing active remodeling that has emerged as a key mediator of this process. EGFL7 expression is associated with poor outcome in several cancers, making it a promising target for imaging or therapeutic strategies. Here, EGFL7 is explored as a molecular target for active neovascularization. Using a combinatorial peptide screening approach, we describe the discovery and characterization of a novel high affinity EGFL7-binding peptide, E7p72, that specifically targets human endothelial cells. Viral nanoparticles decorated with E7p72 peptides specifically target tumor-associated neovasculature with high specificity as assessed by intravital imaging. This work highlights the value of EGFL7 as a target for angiogenic vessels and opens the door for novel targeted therapeutic approaches.

Prognostic importance of circulating epidermal growth factor-like domain 7 in patients with metastatic colorectal cancer treated with chemotherapy and bevacizumab

High tumor expression of epidermal growth factor-like domain 7 (EGFL7) has been associated with a poor prognosis in colorectal cancer. The aim of the current study was to investigate the possible prognostic impact of circulating EGFL7 (cir-EGFL7), combined with single nucleotide polymorphism (SNP) analyses, in patients with metastatic colorectal cancer (mCRC) treated with first line chemotherapy and bevacizumab. A total of 88 patients were included. Serum was collected prior to treatment initiation, at first evaluation after 3 weeks, and at progression. Cir-EGFL7 was analysed by the enzyme-linked immunosorbent assay (ELISA) technique. The SNPs were analysed by real-time qPCR based on DNA from whole blood. Endpoints were response rate (RR), progression free survival (PFS), and overall survival (OS). Cir-EGFL7 decreases after administration of chemotherapy plus bevacizumab. Baseline levels of cir-EGFL7 were significantly related to PFS and OS, p = 0.0431 and p = 0.0017, respectively, with increasing cir-EGFL7 levels associated with a worse prognosis. Circulating EGFL7 was not associated with RR. The SNP analyses revealed a significant relationship between rs1051851 and OS, p = 0.030. This study demonstrates that cir-EGFL7 changes during treatment with chemotherapy plus bevacizumab and that baseline levels and genetic variations may influence the overall prognosis of patients with mCRC. The findings call for further validation.

Expression of epidermal growth factor-like domain 7 may be a predictive marker of the effect of neoadjuvant chemotherapy for locally advanced uterine cervical cancer

Neoadjuvant chemotherapy (NAC) followed by hysterectomy may be effective for the treatment of locally advanced uterine cervical cancer and improve patient prognosis. It is important to identify markers that are able to predict whether NAC may be successful. Epidermal growth factor-like domain 7 (EGFL7) regulates vascular sprouting in blood vessel formation. In numerous types of human cancer, EGFL7 is upregulated and inhibits endothelial cell adhesion molecules, decreasing vascular tightness and, thus, increasing vascular permeability. It is considered that the overexpression of EGFL7 is able to inhibit drug delivery, resistance to apoptosis and the epithelial-to-mesenchymal transition. In the current study, 63 patients with locally advanced uterine cervical cancer were reviewed and classified as stage IIIA-IIIB using the International Federation of Gynecology and Obstetrics criteria. These patients (aged <70 years) were treated at Osaka City University Medical School Hospital, Japan, between 1995 and 2010. Tumor tissue samples were obtained by biopsy prior to NAC. The tissue samples were classified as group 1 or 2 depending on the efficacy of NAC. Surgery and radiotherapy were administered in group 1 (n=36), for which NAC was effective. In the patients of group 2 NAC was not effective, and radiotherapy alone was administered (n=27). The expression of EGFL7 and Snail was examined in paraffin-embedded tissue sample sections using the avidin-biotin peroxidase complex method. The results indicated that EGFL7 expression levels were significantly higher in group 2, as compared with group 1 (P<0.001). A similar result was observed for the expression levels of Snail (P=0.001). Group 1 exhibited significantly longer overall survival times compared with group 2 (P=0.001). The patients were also classified into a low EGFL7 expression level group (weighted score of ≤6) and a high EGFL7 expression level group (weighted score of ≥8). NAC was observed to be significantly more effective in the low EGFL7 expression level group (P<0.001), as compared with the high expression level group. The results suggest that the expression levels of EGFL7 may be a potential predictive marker of the efficacy of NAC for the treatment of locally advanced uterine cervical cancer.

High expression levels of egfl7 correlate with low endothelial cell activation in peritumoral vessels of human breast cancer

Tumor blood vessels participate in the immune response against cancer cells and we previously used pre-clinical models to demonstrate that egfl7 (VE-statin) promotes tumor cell evasion from the immune system by repressing endothelial cell activation, preventing immune cells from entering the tumor mass. In the present study, the expression levels of egfl7 and that of ICAM-1 as a marker of endothelium activation, were evaluated in peritumoral vessels of human breast cancer samples. Breast cancer samples (174 invasive and 30 in situ) from 204 patients treated in 2005 were immunostained for CD31, ICAM-1 and stained for egfl7 using in situ hybridization. The expression levels of ICAM-1 and egfl7 were assessed in peritumoral areas using semi-quantitative scales. There was a strong and significant inverse correlation between the expression of ICAM-1 and that of egfl7 in CD31⁺ blood vessels. When the ICAM-1 score increased, the egfl7 score reduced significantly (P=0.004), and vice-versa (Cuzick's test for trend across ordered groups). In order to determine which gene influenced the other gene between egfl7 and ICAM-1, the expression levels of either gene were modulated in endothelial cells. Egfl7 regulated ICAM-1 expression while ICAM-1 had no effects on egfl7 expression in the same conditions. Altogether, these results provide further results that egfl7 serves a regulatory role in endothelial cell activation in relation to immune infiltration and that it is a potential therapeutic target to consider for improving anticancer immunotherapies.

Suppression of the Epidermal Growth Factor-like Domain 7 and Inhibition of Migration and Epithelial-Mesenchymal Transition in Human Pancreatic Cancer PANC-1 Cells

BACKGROUND

Epidermal growth factor-like domain multiple 7 (EGFL7), a secreted protein specifically expressed by endothelial cells during embryogenesis, recently was identified as a critical gene in tumor metastasis. Epithelial-mesenchymal transition (EMT) was found to be closely related with tumor progression. Accordingly, it is important to investigate the migration and EMT change after knock-down of EGFL7 gene expression in human pancreatic cancer cells.

MATERIALS AND METHODS

EGFL7 expression was firstly testified in 4 pancreatic cancer cell lines by real-time polymerase chain reaction (Real-time PCR) and western blot, and the highest expression of EGFL7 was found in PANC-1 cell line. Then, PANC-1 cells transfected with small interference RNA (siRNA) of EGFL7 using plasmid vector were named si-PANC-1, while transfected with negative control plasmid vector were called NC-PANC-1. Transwell assay was used to analyze the migration of PANC-1 cells. Real-time PCR and western blotting were used to detect the expression change of EGFL7 gene, EMT markers like E-Cadherin, N-Cadherin, Vimentin, Fibronectin and transcription factors like snail, slug in PANC-1, NC- PANC-1, and si-PANC-1 cells, respectively.

RESULTS

After successful plasmid transfection, EGFL7 gene were dramatically knock-down by RNA interference in si-PANC-1 group. Meanwhile, migration ability decreased significantly, compared with PANC-1 and NC-PANC-1 group. Meanwhile, the expression of epithelial phenotype marker E-Cadherin increased and that of mesenchymal phenotype markers N-Cadherin, Vimentin, Fibronectin dramatically decreased in si-PANC-1 group, indicating a reversion of EMT. Also, transcription factors snail and slug decreased significantly after RNA interference.

CONCLUSIONS

Current study suggested that highly-expressed EGFL7 promotes migration of PANC-1 cells and acts through transcription factors snail and slug to induce EMT, and further study is needed to confirm this issue.

Epidermal growth factor-like domain 7 promotes cell invasion and angiogenesis in pancreatic carcinoma

Epidermal growth factor-like domain 7 (EGFL7), also known as vascular endothelial stain, was firstly identified as a modulator of smooth muscle cell migration. Though the expression of EGFL7 was reported to be up-regulated during tumorigenesis, the clinical and biological functions of EGFL7 in pancreatic carcinoma (PC) were still not fully elucidated. In this study, we found that the serum EGFL7 level in PC tissues was statistically higher than that in normal subjects (p<0.001), and its level in non-resectable patients was also higher than that in resectable ones (p=0.013). Among these resectable PC patients, the postoperative EGFL7 expression was significantly down-regulated when tumors were resected (p=0.018). Using the immunohistochemistry method, our results demonstrated that the positive expression of EGFL7 was significantly associated with the TNM stage (p=0.024), lymph node metastasis (p=0.003) and local invasion (p=0.022), and the EGFL7 expression closely correlated to the micro-vessel density (MVD) in PC tissues by Spearman analysis (r=0.941, p=0.000). In vitro, EGFL7 was silenced by the small interference RNA in PC cells, and our data indicated that down-regulation of EGFL7 did not influence the cycle progression, proliferation, colony formation and apoptosis of PC cells (p>0.05), whereas inhibition of EGFL7 expression could decrease PaCa-2 cell invasion (p<0.05). More interestingly, by tubular formation, Chick embryo chorioallantoic membrane (CAM) and ELISA assays, our results revealed that silencing EGFL7 expression represented a strong inhibiting effect on tubular formation of micro-vessels through down-regulating the protein levels of VEGF and Ang-2 (p<0.05). Our results raised the possibility of using EGFL7as a potential prognostic biomarker and therapy target of PC, and down-regulation of EGFL7 might be considered to be a potentially important molecular treatment strategy for patients with PC.

Chloride intracellular channel 1 (CLIC1) is activated and functions as an oncogene in pancreatic cancer

Chloride intracellular channel 1 (CLIC1), a newly discovered member of the chloride channel protein family, has been implicated in multiple human cancers. However, little is known with regard to its expression and biological functions in pancreatic cancer. In this study, we focused on the clinical significance and biological functions of CLIC1 in pancreatic cancer and found that this protein was overexpressed in pancreatic cancer tissues. Patients with CLIC1-positive tumours had worse overall survival than those with CLIC1-negative tumours. Furthermore, the treatment of pancreatic cancer cell lines with CLIC1-targeting siRNA oligonucleotides significantly reduced cell proliferation and diminished anchorage-independent growth on both soft agar and cell migration. These data indicate that CLIC1 acts as a putative oncogene in pancreatic cancer and may represent a novel diagnostic and therapeutic target for pancreatic cancer.