Department of Oncology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University, Chongqing, China.
PLoS One. 2012;7(4):e35378. doi: 10.1371/journal.pone.0035378. Epub 2012 Apr 9.
The extra domain A (EDA)-containing fibronectin (EDA-FN), an alternatively spliced form of the extracellular matrix protein fibronectin, is predominantly expressed in various malignancies but not in normal tissues. In the present study, we investigated the potential pro-lymphangiogenesis effects of extra domain A (EDA)-mediated vascular endothelial growth factor-C (VEGF-C) secretion in colorectal carcinoma (CRC). We detected the expressions of EDA and VEGF-C in 52 human colorectal tumor tissues and their surrounding mucosae by immunohistochemical analysis, and further tested the correlation between the expressions of these two proteins in aforementioned CRC tissues. Both EDA and VEGF-C were abundantly expressed in the specimens of human CRC tissues. And VEGF-C was associated with increased expression of EDA in human CRC according to linear regression analysis. Besides, EDA expression was significantly correlated with lymph node metastasis, tumor differentiation and clinical stage by clinicopathological analysis of tissue microarrays containing tumor tissues of 115 CRC patients. Then, human CRC cell SW480 was transfected with lentivectors to elicit expression of shRNA against EDA (shRNA-EDA), and SW620 was transfected with a lentiviral vector to overexpress EDA (pGC-FU-EDA), respectively. We confirmed that VEGF-C was upregulated in EDA-overexpressed cells, and downregulated in shRNA-EDA cells. Moreover, a PI3K-dependent signaling pathway was found to be involved in EDA-mediated VEGF-C secretion. The in vivo result demonstrated that EDA could promote tumor growth and tumor-induced lymphangiogenesis in mouse xenograft models. Our findings provide evidence that EDA could play a role in tumor-induced lymphangiogenesis via upregulating autocrine secretion of VEGF-C in colorectal cancer, which is associated with the PI3K/Akt-dependent pathway.
外显子 A（EDA）包含的纤连蛋白（EDA-FN）是细胞外基质蛋白纤连蛋白的一种选择性剪接形式，主要在各种恶性肿瘤中表达，但在正常组织中不表达。在本研究中，我们研究了外显子 A（EDA）介导的血管内皮生长因子-C（VEGF-C）分泌在外结肠直肠癌（CRC）中的潜在促淋巴管生成作用。我们通过免疫组织化学分析检测了 52 个人类结直肠肿瘤组织及其周围黏膜中 EDA 和 VEGF-C 的表达，并进一步测试了上述 CRC 组织中这两种蛋白表达之间的相关性。在人类 CRC 组织标本中，EDA 和 VEGF-C 均大量表达。根据线性回归分析，VEGF-C 与人类 CRC 中 EDA 的表达增加相关。此外，通过包含 115 例 CRC 患者肿瘤组织的组织微阵列的临床病理分析，EDA 表达与淋巴结转移、肿瘤分化和临床分期显著相关。然后，用慢病毒载体转染人 CRC 细胞 SW480 以引发针对 EDA 的 shRNA（shRNA-EDA）表达，并用慢病毒载体转染 SW620 以过表达 EDA（pGC-FU-EDA）。我们证实，在 EDA 过表达细胞中 VEGF-C 上调，而在 shRNA-EDA 细胞中下调。此外，发现 EDA 介导的 VEGF-C 分泌涉及 PI3K 依赖性信号通路。体内结果表明，EDA 可通过上调大肠癌中自分泌分泌的 VEGF-C 促进肿瘤生长和肿瘤诱导的淋巴管生成。我们的研究结果提供了证据，表明 EDA 可以通过上调大肠癌中的自分泌分泌的 VEGF-C 在外结肠直肠癌中发挥作用，这与 PI3K/Akt 依赖性途径有关。
