Department of Anatomy & Physiology, Kansas State University, College of Veterinary Medicine, Manhattan, KS 66506, USA.
BMC Cancer. 2010 Feb 24;10:67. doi: 10.1186/1471-2407-10-67.
Pancreatic cancer is one of the most aggressive human malignancies, with a very poor prognosis. To evaluate the effect of angiotensin II (Ang II) type 2 receptor (AT2) expression in the host's body on the growth of pancreatic carcinoma, we have investigated the growth of mouse pancreatic ductal carcinoma grafts in syngeneic wild type and AT2 receptor-deficient (AT2-KO) mice.
The role of AT2 receptor-signaling in stromal cells on the growth of murine pancreatic carcinoma cells (PAN02) was studied using various in vitro and in vivo assays. In vivo cell proliferation, apoptosis, and vasculature in tumors were monitored by Ki-67 immunostaining, TUNEL assay, and von Willebrand factor immunostaining, respectively. In the co-culture study, cell proliferation was measured by MTT cell viability assay. All the data were analyzed using t-test and data were treated as significant when p < 0.05.
Our results show that the growth of subcutaneously transplanted syngeneic xenografts of PAN02 cells, mouse pancreatic ductal carcinoma cells derived from the C57/BL6 strain, was significantly faster in AT2-KO mice compared to control wild type mice. Immunohistochemical analysis of tumor tissue revealed significantly more Ki-67 positive cells in xenografts grown in AT2-KO mice than in wild type mice. The index of apoptosis is slightly higher in wild type mice than in AT2-KO mice as evaluated by TUNEL assay. Tumor vasculature number was significantly higher in AT2-KO mice than in wild type mice. In vitro co-culture studies revealed that the growth of PAN02 cells was significantly decreased when grown with AT2 receptor gene transfected wild type and AT2-KO mouse-derived fibroblasts. Faster tumor growth in AT2-KO mice may be associated with higher VEGF production in stromal cells.
These results suggest that Ang II regulates the growth of pancreatic carcinoma cells through modulating functions of host stromal cells; Moreover, Ang II AT2 receptor signaling is a negative regulator in the growth of pancreatic carcinoma cells. These findings indicate that the AT2 receptor in stromal fibroblasts is a potentially important target for chemotherapy for pancreatic cancer.
胰腺癌是人类最具侵袭性的恶性肿瘤之一，预后极差。为了评估血管紧张素 II (Ang II) 型 2 受体 (AT2) 在宿主体内的表达对胰腺癌生长的影响，我们研究了胰腺导管癌细胞 (PAN02) 在同基因野生型和 AT2 受体缺陷型 (AT2-KO) 小鼠中的生长情况。
使用各种体外和体内实验研究了 AT2 受体信号在基质细胞中对小鼠胰腺癌细胞生长的作用。通过 Ki-67 免疫染色、TUNEL 检测和 von Willebrand 因子免疫染色分别监测肿瘤中的细胞增殖、细胞凋亡和血管生成。在共培养研究中，通过 MTT 细胞活力测定法测量细胞增殖。所有数据均采用 t 检验进行分析，当 p < 0.05 时，数据被视为具有统计学意义。
我们的结果表明，与对照野生型小鼠相比，源自 C57/BL6 品系的胰腺导管癌细胞的皮下移植同种异体异种移植物在 AT2-KO 小鼠中的生长速度明显更快。肿瘤组织的免疫组织化学分析显示，在 AT2-KO 小鼠中生长的异种移植物中 Ki-67 阳性细胞明显更多。TUNEL 检测评估的细胞凋亡指数略高于野生型小鼠。AT2-KO 小鼠中的肿瘤血管生成数量明显高于野生型小鼠。体外共培养研究表明，当与转染野生型和 AT2-KO 小鼠来源的成纤维细胞基因的 PAN02 细胞共培养时，PAN02 细胞的生长明显减少。AT2-KO 小鼠中更快的肿瘤生长可能与基质细胞中更高的 VEGF 产生有关。
这些结果表明，Ang II 通过调节宿主基质细胞的功能来调节胰腺癌的生长；此外，Ang II AT2 受体信号是胰腺癌细胞生长的负调节剂。这些发现表明，基质成纤维细胞中的 AT2 受体可能是胰腺癌化疗的一个潜在重要靶点。
