Department of Ophthalmology, University of Cologne, Cologne, Germany.
Invest Ophthalmol Vis Sci. 2014 Apr 25;55(4):2697-704. doi: 10.1167/iovs.13-13254.
Tumor-derived VEGF-A, apart from expediting sufficient vascularization, subsequent tumor growth, and metastatic spread, can act on malignant cells themselves provided that VEGF receptors 1 or 2 (VEGF-R1, -R2) are co-expressed. The study goal was to investigate whether such autocrine VEGF-A signaling exists in uveal melanoma (UM).
Primary (MEL-270, OM-431) and metastatic (OMM-2.3, OMM-2.5) UM cell lines were analyzed for VEGF-A, VEGF-R1, and VEGF-R2 expression by RT-PCR, ELISA (VEGF-A protein), and immunocytochemistry (VEGF receptors). Proliferation of UM cells incubated with neutralizing anti-VEGF-A antibody bevacizumab (≤ 2.5 mg/mL), or VEGF-A (≤ 100 ng/mL) was assessed by bromodeoxyuridine (BrdU) ELISA. It was measured by real-time PCR, whether VEGF-A (100 ng/mL) modulated the expression ratio of VEGF-A itself and its antiangiogenic antagonist pigment epithelium-derived factor (PEDF).
All UM cells expressed VEGF-A, VEGF-R1, VEGF-R2 mRNA, and protein. In each cell line, the proliferation was stimulated by VEGF-A or inhibited by blocking VEGF-A, or both: bevacizumab significantly decreased the proliferation in MEL-270 (P = 0.005), OMM-2.3 (P = 0.001), and OMM-2.5 (P = 0.011). Increased VEGF-A signaling significantly raised the proliferation in MEL-270, OM-431 (P < 0.001, respectively), and OMM-2.3 (P = 0.043) in a dose-dependent manner but did not significantly change the VEGF-A/PEDF mRNA expression ratio.
Autocrine VEGF-A signaling seems to be present in UM, sustaining the proliferation of both primary and metastatic UM cells. Apparently, VEGF-A signaling in UM cells neither acts retroactively on VEGF-A expression, in the sense of a feedback loop, nor contributes to a pro-angiogenic shift of the VEGF-A/PEDF ratio.
肿瘤衍生的 VEGF-A 除了加速足够的血管生成、随后的肿瘤生长和转移扩散外，如果共表达血管内皮生长因子受体 1 或 2（VEGF-R1、-R2），还可以作用于恶性细胞本身。本研究的目的是研究葡萄膜黑色素瘤（UM）中是否存在这种自分泌的 VEGF-A 信号。
通过 RT-PCR、ELISA（VEGF-A 蛋白）和免疫细胞化学（VEGF 受体）分析原发性（MEL-270、OM-431）和转移性（OMM-2.3、OMM-2.5）UM 细胞系中 VEGF-A、VEGF-R1 和 VEGF-R2 的表达。用溴脱氧尿苷（BrdU）ELISA 评估用中和抗 VEGF-A 抗体贝伐单抗（≤2.5mg/mL）或 VEGF-A（≤100ng/mL）孵育的 UM 细胞的增殖。通过实时 PCR 测量 VEGF-A（100ng/mL）是否调节 VEGF-A 本身及其抗血管生成拮抗剂色素上皮衍生因子（PEDF）的表达比率。
所有 UM 细胞均表达 VEGF-A、VEGF-R1、VEGF-R2mRNA 和蛋白。在每种细胞系中，VEGF-A 刺激增殖或阻断 VEGF-A 抑制增殖：贝伐单抗显著降低 MEL-270（P=0.005）、OMM-2.3（P=0.001）和 OMM-2.5（P=0.011）中的增殖。VEGF-A 信号的增加以剂量依赖性方式显著增加 MEL-270、OM-431（P<0.001）和 OMM-2.3（P=0.043）中的增殖，但对 VEGF-A/PEDF mRNA 表达比率无显著影响。
自分泌 VEGF-A 信号似乎存在于 UM 中，维持原发性和转移性 UM 细胞的增殖。显然，UM 细胞中的 VEGF-A 信号既不会以反馈环的形式对 VEGF-A 表达产生反向作用，也不会导致 VEGF-A/PEDF 比值的促血管生成转变。
