Expression profiling and significance of VEGF-A, VEGFR2, VEGFR3 and related proteins in endometrial carcinoma
Introduction
Angiogenesis is an important but poorly understood process which allows tumors to grow and to metastasize. Several angiogenic growth factors have been found which promote and regulate angiogenesis in physiological conditions, as well as in tumor progression [1], [2]. Of these, the most studied is the vascular endothelial growth factor (VEGF) family, comprising VEGF-A to -D and their receptors VEGFR1 (flt-1), VEGFR2 (KDR/flk-1) and VEGFR3 (flt-4). Although VEGF-A and -B act primarily via VEGFR1 and -R2, while VEGF-C and -D act via VEGFR3 (and appear most important in lymphangiogenesis), cross-signalling between the different ligands and receptors occurs. Physiologically, VEGFs are secreted by fibroblasts and inflammatory cells, and bind to VEGFRs on endothelial cells to promote angiogenesis. However, in tumor angiogenesis, expression of these ligands and receptors are also seen in tumor cells, resulting in both autocrine-induced tumor growth and angiogenesis.
However, the VEGF/VEGFR pathway is not the sole pathway for angiogenesis. Other signalling pathways, such as fibroblast growth factor 2 (FGF2) and its receptors FGFR1 and FGFR2, epidermal growth factor (EGF) and its receptor EGFR [3] are also involved. In addition, interleukin-8 (IL-8), a pro-inflammatory cytokine, which binds to its receptors CXC chemokine receptor 1 (CXCR1) and CXCR2, also initiates many different signalling pathway resulting in angiogenesis, mitogenesis and motogenesis [4]. These other pathways may explain the resistance of tumors to VEGF inhibition therapy [2].
The expression of these various angiogenic factors and their receptors have therefore been studied and found to be expressed in a wide variety of tumors, including breast, pancreatic and colorectal cancers [5], [6], [7]. Their expressions in endometrial cancers have also been studied in the past [8], [9], [10], [11]. However, some of these studies have shown conflicting data, with some showing increased expression compared with normal endometrium, while others do not show this. Similarly, some studies have shown the expression of VEGFs, or their receptors to be correlated with prognostic factors, while others have not shown this correlation.
In this paper, we studied the expression of VEGF-A, VEGFR2 and VEGFR3 in endometrial tumors. We correlated the expressions of these receptors with EGFR, CXCR1 and CXCR2 expressions, as well as other pathological prognostic factors and clinical outcome.
Section snippets
Case and sample selection
A cohort of patients diagnosed with endometrial carcinomas was identified from the database of Hammersmith Hospital, London, United Kingdom. All patients had undergone a total hysterectomy with bilateral salpingo-oopherectomy at Hammersmith Hospital. Ethical approval for the use of human tissue was obtained from the Hammersmith and Queen Charlotte’s and Chelsea Hospitals Research Ethics Committee (Reference number: 2000/5875).
The clinical history and histopathological reports and slides were
Hypothesis
We propose that the expression of VEGF-A, VEGFR2 and VEGFR3 is increased in endometrial tumors, and that they may provide valuable prognostic information on endometrial cancers. We also propose that cross-talk exists between these factors/receptors and other receptors, such as EGFR, CXCR1 and CXCR2, which may play a role in tumor progression.
Patients
A total of 76 patients diagnosed with endometrial adenocarcinomas were included in the study. The median age of the patients was 64 years (minimum age 39 years, maximum 88 years).
Of the 76 cases, there were 43 endometrioid adenocarcinomas, 22 serous carcinomas, 7 clear cell carcinomas and 4 carcinosarcomas. There were 10 tumors classified as grade I, 25 as grade II and 41 as grade III (including all serous, clear cell and carcinosarcomas, which are considered high grade). Lymphovascular invasion
Discussion
Endometrial angiogenesis is part of cyclical endometrium, and is regulated by angiogenic growth factors, possibly under the influence of ovarian steroids. A previous study found VEGF-A, FGF2, EGF and their receptors were all expressed in normal endometrium, with highest expression in the secretory phase [14]. In addition, studies have shown VEGFR1 and VGFR2 expression changes during the endometrial cycle [15].
In this study, we showed increased expression of VEGFR2 and VEGFR3 mRNA by qRT-PCR in
Conclusion
In summary, in this study, we found that the expression of VEGFR2 and VEGFR3 are increased in endometrial cancers. Furthermore, the expressions of the receptors are correlated with each other and with EGFR, CXCR1 and CXCR2, indicating cross-talk between these pathways. Finally, VEGFR3 expression correlated with tumor stage, suggesting it may be a useful prognostic tool, and with a trend to correlation with DFS, may also have therapeutic implications and will help identify patients with better
Contributions of authors
JW, MEB wrote the paper. MEB, AT, EL designed the research study. JW, RS, PT, YH, IB, LE performed the research. RS, PT, LE contributed essential reagents or tools. JW, YH, IB analysed the data.
Disclosure/conflicts of interest
We declare that there is no actual or potential conflict of interest including any financial, personal or other relationships with other people or organizations regarding the material in the manuscript that could inappropriately influence (bias) our work. These include employment, consultancies, stock ownership, honoraria, paid expert testimony, patent applications/registrations and grants and any other funding.
Acknowledgement
The authors are grateful for support from the NIHR Biomedical Research Centre funding scheme.
References (28)
- et al.
Regulation of VEGF signaling by membrane traffic
Cell Signal
(2012) The expression of interleukin-8 and interleukin-8 receptors in endometrial carcinoma
Cytokine
(2012)Neoangiogenesis and expression of hypoxia-inducible factor 1alpha, vascular endothelial growth factor, and glucose transporter-1 in endometrioid type endometrium adenocarcinomas
Gynecol Oncol
(2008)Interleukin 8 and vascular endothelial growth factor – prognostic factors in human gastric carcinomas?
Eur J Cancer
(2001)- et al.
CXCL8/IL8 stimulates vascular endothelial growth factor (VEGF) expression and the autocrine activation of VEGFR2 in endothelial cells by activating NFkappaB through the CBM (Carma3/Bcl10/Malt1) complex
J Biol Chem
(2009) - et al.
VEGFA and tumor angiogenesis
J Intern Med
(2013) - et al.
The VEGF pathway in cancer and disease: responses, resistance, and the path forward
Cold Spring Harb Perspect Med
(2012) - et al.
The interleukin-8 pathway in cancer
Clin Cancer Res
(2008) Prognostic significance of epidermal growth factor receptor and vascular endothelial growth factor receptor in colorectal adenocarcinoma
APMIS
(2011)Epidermal growth factor receptor and vascular endothelial growth factor receptor 2 are specific biomarkers in triple-negative breast cancer. Results from a controlled randomized trial with long-term follow-up
Breast Cancer Res Treat
(2010)