Endothelin B receptor expression in human astrocytoma: association with clinicopathological variables and survival outcomes

Prognostic role of Ki-67 in glioblastomas excluding contribution from non-neoplastic cells

Survival of glioblastoma patients varies and prognostic markers are important in the clinical setting. With digital pathology and improved immunohistochemical multiplexing becoming a part of daily diagnostics, we investigated the prognostic value of the Ki-67 labelling index (LI) in glioblastomas more precisely than previously by excluding proliferation in non-tumor cells from the analysis. We investigated the Ki-67 LI in a well-annotated population-based glioblastoma patient cohort (178 IDH-wildtype, 3 IDH-mutated). Ki-67 was identified in full tumor sections with automated digital image analysis and the contribution from non-tumor cells was excluded using quantitative double-immunohistochemistry. For comparison of the Ki-67 LI between WHO grades (II-IV), 9 IDH-mutated diffuse astrocytomas and 9 IDH-mutated anaplastic astrocytomas were stained. Median Ki-67 LI increased with increasing WHO grade (median 2.7%, 6.4% and 27.5%). There was no difference in median Ki-67 LI between IDH-mutated and IDH-wildtype glioblastomas (p = 0.9) and Ki-67 LI was not associated with survival in glioblastomas in neither univariate (p = 0.9) nor multivariate analysis including MGMT promoter methylation status and excluding IDH-mutated glioblastomas (p = 0.2). Ki-67 may be of value in the differential diagnostic setting, but it must not be over-interpreted in the clinico-pathological context.

Overexpression of endothelin B receptor in glioblastoma: a prognostic marker and therapeutic target?

Background

Glioblastoma (GBM) is the most common malignant brain tumor with median survival of 12-15 months. Owing to uncertainty in clinical outcome, additional prognostic marker(s) apart from existing markers are needed. Since overexpression of endothelin B receptor (ETBR) has been demonstrated in gliomas, we aimed to test whether ETBR is a useful prognostic marker in GBM and examine if the clinically available endothelin receptor antagonists (ERA) could be useful in the disease treatment.

Methods

Data from The Cancer Genome Atlas and the Gene Expression Omnibus database were analyzed to assess ETBR expression. For survival analysis, glioblastoma samples from 25 Swedish patients were immunostained for ETBR, and the findings were correlated with clinical history. The druggability of ETBR was assessed by protein-protein interaction network analysis. ERAs were analyzed for toxicity in in vitro assays with GBM and breast cancer cells.

Results

By bioinformatics analysis, ETBR was found to be upregulated in glioblastoma patients, and its expression levels were correlated with reduced survival. ETBR interacts with key proteins involved in cancer pathogenesis, suggesting it as a druggable target. In vitro viability assays showed that ERAs may hold promise to treat glioblastoma and breast cancer.

Conclusions

ETBR is overexpressed in glioblastoma and other cancers and may be a prognostic marker in glioblastoma. ERAs may be useful for treating cancer patients.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4012-7) contains supplementary material, which is available to authorized users.

Genetic effects of XRCC4 and ligase IV genes on human glioma

Ligase IV and XRCC4 genes, important molecules in the nonhomologous end-joining pathway for repairing DNA double-strand breaks, may play crucial roles in carcinogenesis. To detect their effects on the risk of human glioma, their gene expression differences between 110 human glioma tissues and 50 healthy brain tissues were determined using quantitative real-time PCR. Furthermore, two tagging single nucleotide polymorphisms (SNPs) in ligase IV and four SNPs in XRCC4 genes were genotyped in 317 glioma patients and 352 healthy controls. The association of glioma and ligase IV/XRCC4 was evaluated using methods for SNP, haplotype, and gene-gene interaction analysis. Compared with those in normal brain tissues, the relative gene expression levels of ligase IV and XRCC4 were significantly downregulated in glioma tissue (P=0.0017 and 0.0006, respectively). Single SNP analysis indicated that only rs10131 in ligase IV remained significantly associated with glioma (P=0.0036) after 10 000 permutation tests. Haplotype analysis showed that the haplotype profiles of ligase IV and XRCC4 were significantly different between glioma patients and healthy controls (P=0.004 and 3.13E-6, respectively). Finally, the gene-gene interaction analysis suggested that the three-locus model (rs1805388, rs10131, and rs2075685) was the best model for ligase IV and XRCC4 to have interaction effects on the risk of glioma. In conclusion, both ligase IV and XRCC4 may act in concert to modulate the development of glioma.

Endothelin B receptor expression in malignant gliomas: the perivascular immune escape mechanism of gliomas

In order to clarify the role of endothelin B receptors (ETBRs) in gliomas, we analyzed cell cultures and surgical specimens of gliomas using RT-PCR and immunohistochemistry. RT-PCR measured the absolute expression of ETBR mRNA in twelve samples, which included gliomas that were classified using the World Health Organization (WHO) classification system Grade I-IV, as well as two glioblastoma cell lines (CCF-STTG1 and U87-MG). Using immunohistochemistry, 77 glioma specimens were evaluated for their expression of ETBR and infiltrating T lymphocytes, including an analysis of cytotoxic T cells (CTLs) and regulatory T lymphocytes (Tregs). The number of ETBR-positive vessels in the glioblastomas (Grade IV) was significantly higher than in other grades of gliomas (comparisons to Grade IV, Grade I: p = 0.0323, Grade II: p = 0.0009, Grade III: p = 0.0273). The ETBR expression rate (defined as the number of ETBR-positive blood vessels divided by the total number of blood vessels) in the glioblastomas was higher than the ETBR expression rate in the low-grade gliomas (compared to Grade IV, Grade I: p = 0.0132, Grade II: p = 0.0018, Grade III: p = 0.0745). In addition, the cases which had an ETBR expression rate of 50 % or higher exhibited fewer infiltrating CTLs and more infiltrating Tregs compared to the cases with an ETBR expression rate <50 % (CTLs: p = 0.0342; Tregs: p = 0.0175). Isocitrate dehydrogenase 1 (IDH-1) mutations were identified in 21 cases, but there was no correlation between ETBR expression and IDH-1 mutations for any WHO grade. These results suggest that ETBR expression during neo-angiogenesis may interfere with the homing of CTLs around the tumor and be involved in the immune escape mechanism of gliomas.

Ki-67 is a valuable prognostic factor in gliomas: evidence from a systematic review and meta-analysis

Ki-67 has been widely used as an indicator of cell proliferation in gliomas. However, the role of Ki-67 as a prognostic marker is still undefined. Thus, we conducted a meta-analysis of the published literatures in order to clarify the impact of Ki-67 on survival in glioma cases. Eligible studies were identified in PubMed, EMBASE, ISI Web of Science, Cochrane Central Register of Controlled Trials, Science Direct and Wiley Online Library with the last search updated on August 31, 2014. The clinical characteristics, overall survival (OS) and progression- free survival (PFS) together with Ki-67 expression at different time points were extracted. A total of 51 studies, covering 4,307 patients, were included in the current meta-analysis. The results showed that overexpression of Ki-67 can predict poor OS (HR=1.66, 95%CI: 1.53-1.80; Z=11.87; p=0.000) and poor PFS (HR=1.67, 95%CI: 1.47-1.91; Z=7.67; p=0.000) in gliomas. Moreover, subgroup analyses also indicated that high level of Ki-67 expression was related to poor OS and PFS in glioma patients regardless of region, pathology type, cut-off value and statistical method. In conclusion, the current meta-analysis revealed that Ki-67 expression might be a predicative factor for poor prognosis of glioma patients, emphasizing its importance as a predictor.

Endothelin B receptor expression correlates with tumour angiogenesis and prognosis in oesophageal squamous cell carcinoma

Background:

The endothelin axis has been shown to have a pivotal role in several human malignancies. The aim of this study was to clarify the clinical importance of endothelin receptor type B (ETBR) in human oesophageal squamous cell carcinoma (OSCC).

Methods:

We evaluated ETBR expression in 107 patients with OSCC by immunohistochemistry. Microvessel density (MVD) and lymphatic vessel density were assessed by CD31 and D2-40 immunostaining, respectively. Furthermore, CD4, CD8, and CD45RO+ tumour-infiltrating lymphocytes (TILs) were immunohistochemically analysed.

Results:

Sixty-one (57%) cases showed high expression of ETBR. Endothelin receptor type B expression was correlated with several clinicopathological factors including tumour differentiation, tumour depth, and lymph node metastasis. The overall and disease-specific survival rates were significantly lower in patients with high ETBR expression than patients with low expression. Furthermore, multivariate analysis revealed that ETBR status was an independent prognostic factor for patient survival. Mechanistic analysis indicated that MVD was significantly higher in tumour tissues with high ETBR expression compared with those with low expression, suggesting that angiogenesis may be a key mechanism in tumour progression and metastasis of OSCC mediated by ETBR expression. By contrast, there were no significant correlations between TILs and ETBR expression.

Conclusion:

Endothelin receptor type B has a pivotal role in oesophageal cancer and may be therapeutic target for this intractable malignancy.