【作者】 余继海；

【导师】 许戈良； 徐荣楠； 柴仲培； 李建生；

【作者基本信息】 安徽医科大学 ， 外科学， 2003， 硕士

【摘要】 肿瘤的生长是血管生成依赖性的，肿瘤新生血管成为临床肿瘤治疗的一个新的靶点，目前在美国全国癌症研究所共有35个抗肿瘤血管生成药物进行临床试验。生长抑素（somatostatin,SS）及其类似物具有广泛的生物学效应，不仅可以抑制多种神经内分泌肿瘤生长和激素的释放，诸多研究表明还可以直接抑制肿瘤血管新生（neovascularization）。在正常人体血管和肿瘤血管内皮细胞中均已检测出不同亚型的生长抑素受体表达，生长抑素及其类似物通过与相应的受体结合而介导其效应。在生长抑素对不同肿瘤细胞系的离体实验表明，生长抑素的受体后信号传导由酪氨酸蛋白磷酸酶（PTP）介导，调节Rb蛋白磷酸化状态而使细胞周期阻滞于G₀／G₁期，其中可有p53、p21或p27蛋白的参与；通过SSTR-3、SSTR-2介导而诱导细胞凋亡，分别依赖和不依赖于p53蛋白。另外，由于血管内皮细胞存在VEGF自分泌调控，后者为内皮特异性有丝分裂原，可以刺激内皮细胞分裂增殖，在离体中生长抑素可能通过调节VEGF自分泌机制而影响内皮细胞增殖。在实验中我们选用新生儿脐带，经酶消化法分离脐静脉内皮细胞进行体外培养，通过细胞形态学、细胞表型和细胞分泌蛋白的检测证实为血管内皮细胞。然后将不同浓度倍比稀释的生长抑素八肽类似物奥曲肽加入到培养细胞中，MTT法发现细胞增殖抑制率达22.1％—46.7％，流式细胞术检测表明，细胞周期被阻滞于G₀／G₁期，同时见细胞凋亡。运用RT-PCR法检测出HUVEC表达生长抑素受体3（SSTR-3），未检测出SSTR-1、SSTR-2、SSTR-4和SSTR-5的表达。因为奥曲肽与SSTR-2、SSTR-3和SSTR-5有高度的亲和力，我们认为奥曲肽是通过与HUVSC的SSTR-3结合，使细胞周期阻滞并诱导细胞凋亡的发生，从而抑制内皮细胞的增殖。内皮细胞增殖是血管生成的关键步骤之一，因此我们的实验结果表明，生长抑素类似物奥曲肽可能通过直接影响内皮细胞而发挥抗肿瘤血管生成作用。更多还原

【Abstract】 It has been proposed that solid tumor growth is angiogenesis dependent. Neovascularization in tumor may be a new target in cancer therapy. Thirty-five antiangiogenic therapies are currently being evaluated in clinical trials in nation cancer institute (NCI). Somatostatin (SS), as a neuroendocrine peptide, exerts a wide range physiological action. It not only inhibits neovascularization, also inhibits neovascularization. There are some studies that demonstrated differential expression of somatostatin receptor subtypes (SSTR) in human blood vessels and peritumoral veins. Currently available data suggest that somatostatin and its analogues might inhibit angiogenesis directly through somatostin receptors present on endothelial cells and indirectly through the inhibition of growth factors secretion such as vascular endothelial growth factor (VEGF) and reducing monocyte chemotaxis. In this experiment, we cultured cells obtained from healthy human umbilical cord vein, and indentified these cells according to the antigens expressed and their morphology by invert phase-contract microscope. With treatment of SS analogue octreotide , the human umbilical vein endothelial cell (HUVEC) growth inhibition, as assessed by MTT assay was observed. The increase in the number of cells in S phase by fluorescence activated flow cytometry analysis (FM). Interestingly, apoptosis was induced too. Using reverse transcription polymerasc chain reaction(RT-PCR), SSTR-3 were predominantly expressed , whereas SSTR-1 SSTR-2 ,SSTR-4 and SSTR-5 were undetectable in HUVEC . Because octreotide has high affinity for SSTR-2 and , to a lesser extent , SSTR-5 and SSTR-2 ,we concluded that octreotide antiproliferative effects may result from blockadeof mitogenic growth signal or induction of apoptosis following interaction with SSTR-3 . Endotheiial cell proliferation is the key step of angiogenesis, suggesting that octreotide may be an antitumor angiogenic compound directly affecting endothelial cells.更多还原