Viglietto G, Romano A, Maglione D, Rambaldi M, Paoletti I, Lago C T, Califano D, Monaco C, Mineo A, Santelli G, Manzo G, Botti G, Chiappetta G, Persico M G
Istituto Nazionale dei Tumori, Fondazione Senatore Pascale, Naples, Italy.
Oncogene. 1996 Aug 1;13(3):577-87.
Neoangiogenesis is a prerequisite for tumor growth and metastasis. In germ cell cancer patients with the disease limited to the testicle (stage A), tumor-associated neovascularization is predictive of metastatic disease (stage B). To investigate the molecular mechanisms underlying neovascularization in human germ cell tumors (GCTs), we analysed the expression of two angiogenic growth factors, vascular endothelial growth factor (VEGF) and placenta growth factor (P1GF), and of their receptors (FLT-1) and Flk-1/KDR) in a panel of testicular tumors. In this study we show a marked increase in VEGF expression in 36/44 (81.8%) primary testicular-derived GCTs, as compared to normal testis, that significantly correlates with a high density of intratumor microvessels (r = 0.72461, P < 0.001; n = 24). As determined by RT - PCR and/or Western blot, the predominant VEGF isoforms expressed in GCTs are the VEGF121 and VEGF165, which are more efficiently secreted by the cells, and thus more active in eliciting angiogenesis. Conversely, in the case of PIGF, only a weak correlation with the vascular density of tumors is observed (r = 0.26599, P < 0.05; n = 24). Northern blot analysis also revealed significant up-regulation of VEGF/ PIGF receptors in highly vascularized germ cell tumors, compared to normal testes. These findings suggest that VEGF may act in a paracrine manner to induce neovascularization, oedema extravasation and cyst formation in human germ cell tumors. The correlation between VEGF expression and the vascular density of tumors, suggest that the evaluation of VEGF expression may be of help in predicting patients at risk for metastatic diseases. Finally, we demonstrate that VEGF up-regulation may occur at the RNA level since no gene amplification is observed; conversely, in in vitro models such as the embryonal stem cell line NTERA-2 and the choricarcinoma JEG-3 cell line, VEGF (but not PIGF) mRNA expression is regulated by hypoxic stress.
新生血管形成是肿瘤生长和转移的前提条件。在疾病局限于睾丸的生殖细胞癌患者（A期）中，肿瘤相关的新生血管形成可预测转移性疾病（B期）。为了研究人类生殖细胞肿瘤（GCT）中新生血管形成的分子机制，我们分析了一组睾丸肿瘤中两种血管生成生长因子，即血管内皮生长因子（VEGF）和胎盘生长因子（P1GF）及其受体（FLT-1和Flk-1/KDR）的表达。在本研究中，我们发现与正常睾丸相比，36/44（81.8%）原发性睾丸来源的GCT中VEGF表达显著增加，这与肿瘤内微血管的高密度显著相关（r = 0.72461，P < 0.001；n = 24）。通过RT-PCR和/或蛋白质印迹法测定，GCT中表达的主要VEGF异构体是VEGF121和VEGF165，它们由细胞更有效地分泌，因此在引发血管生成方面更具活性。相反，对于PIGF，仅观察到与肿瘤血管密度的弱相关性（r = 0.26599，P < 0.05；n = 24）。Northern印迹分析还显示，与正常睾丸相比，高度血管化的生殖细胞肿瘤中VEGF/PIGF受体显著上调。这些发现表明，VEGF可能以旁分泌方式作用，诱导人类生殖细胞肿瘤中的新生血管形成、水肿外渗和囊肿形成。VEGF表达与肿瘤血管密度之间的相关性表明，评估VEGF表达可能有助于预测转移性疾病风险患者。最后，我们证明VEGF上调可能发生在RNA水平，因为未观察到基因扩增；相反，在体外模型如胚胎干细胞系NTERA-2和绒毛膜癌JEG-3细胞系中，VEGF（而非PIGF）mRNA表达受缺氧应激调节。
