Background:Vascular endothelial growth factor action in tumour angiogenesis is well characterised; nevertheless, it functions as a key element in the promotion of the immune system's evasion by tumours. We sought to investigate the possible direct effect of VEGF on T-cell activation and through which type of VEGF receptor it exerts this effect on cells isolated from ovarian cancer patients' ascites.Methods:T cells isolated from the ascites of ovarian cancer patients were cultured with anti-CD3 and IL-2, with or without VEGF for 14 days and the number of viable T cells was counted. Cytotoxic activity of cultured T cells and expression of VEGF receptor-2 (VEGFR-2), was assayed.Results:The addition of VEGF in cultures significantly reduced the number and proliferation rate of T cells in a dose-dependent manner and CD3+ T cells expressed VEGFR-2 on their surface upon activation. Experiments with specific anti-VEGFR-2 antibodies revealed that the direct suppressive effect of VEGF on T-cell proliferation is mediated by VEGFR-2. We also showed that VEGF significantly reduced the cytotoxic activity of T cells.Conclusion:Our study showed that ascites-derived T cells secrete VEGF and express VEGFR-2 upon activation. Vascular endothelial growth factor directly suppresses T-cell activation via VEGFR-2.

The role of vascular endothelial growth factor (VEGF) in tumor angiogenesis is well characterized; nevertheless, it is also a key element in promoting tumor evasion of the immune system by downregulating dendritic cell maturation and thus T cell activation. We sought to investigate the possible direct effect of VEGF on T cell activation and through which type of VEGF receptor (VEGFR) it exerts this effect. Circulating T cells from healthy donors and ovarian cancer patients were expanded in cultures with anti‐CD3 and IL‐2 with or without VEGF for 14 days, and the number of T cells was assessed. Cultured T cells were also tested for their cytotoxic activity in a standard 4‐hr 51Cr‐release assay, and the expression of VEGFRs 1, 2 and 3 was assayed by flow cytometry, immunocytochemistry and Western blotting. To assess the ability of activated T cells to secrete VEGF, levels in culture supernatants were measured by enzyme linked immunosorbent assay. The addition of VEGF in cultures significantly reduced T cell proliferation in a dose‐dependent manner. Protein expression studies demonstrated that CD3+ T cells express VEGFR‐2 on their surface upon activation. Experiments with anti‐VEGFR‐2 antibodies showed that the direct suppressive effect of VEGF on T cell proliferation is mediated by VEGFR‐2. We also showed that VEGF significantly reduced the cytotoxic activity of T cells and that activated T cells secrete VEGF in the culture environment. Overall, our study shows that T cells secret VEGF and expresses VEGFR‐2 upon activation. VEGF directly suppresses T cell activation via VEGF receptor type 2.

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Objective: GHRH is secreted by the hypothalamus and, upon binding to specific GHRH receptors in the pituitary, stimulates growth hormone (GH) production and release from the pituitary. In addition to this neuroendocrine action, accumulated evidence implies additional roles for GHRH in carcinogenesis in non-pituitary tissues. In vitro and in vivo studies have shown that splice variant 1 (SV1) of the GHRH receptor, which is widely expressed in non-pituitary tissues and cancers, can mediate the proliferative effects of GHRH. The aim of the present study was to investigate the operation of an autocrine stimulatory loop between GHRH and SV1 in primary breast tumors. Design: Fifty-three primary breast tumors were evaluated for GHRH and SV1 expression. Methods: Expression of GHRH and SV1 was assessed by immunohistochemistry using anti-GHRH SV95 and anti-SV1 2317/5 polyclonal antibodies. Results: About 40% of the specimens tested express GHRH and/or SV1 (approx. 25% each), while in 35% of these positive specimens co-expression of these antigens was detected (P , 0.01). Furthermore, a correlation of GHRH, but not SV1, expression was detected in lobular compared with ductal carcinomas. Conclusions: These results constitute the first demonstration for the expression of GHRH and SV1 in primary breast cancers, and provide evidence for the operation of an autocrine stimulatory loop between GHRH and SV1 in primary cancers. Our findings indicate that GHRH analogs could have diagnostic and therapeutic applications for the management of breast cancer.European Journal of Endocrinology 151 391-396