Department of Oncology and Southwest Cancer Center, Southwest Hospital, Third Military Medical University, Chongqing 400038, PR China.
Int J Radiat Oncol Biol Phys. 2012 Mar 15;82(4):e685-91. doi: 10.1016/j.ijrobp.2011.09.040. Epub 2011 Dec 28.
Fibronectin extra domain A (EDA) is known to play important roles in angiogenesis, lymphangiogenesis, and metastasis in malignant tumors. The present study examined the effect of EDA on the radioresistance potential of nasopharyngeal carcinoma (NPC).
EDA expression levels in blood samples and tumor tissues of NPC patients were tested by enzyme-linked immunosorbent assay and immunohistochemistry. Radiosensitivity was tested by colony survival assay. Apoptosis was determined by flow cytometry. The expressions of EDA, cleaved caspase 9, cleaved caspase 3, cleaved PARP, Bcl-2, and the levels of phosphorylated FAK, Akt, and JNK were measured by Western blot. Xenografts were used to confirm the effect of EDA on radiosensitivity in vivo.
EDA levels in blood samples of advanced NPC patients were much higher than those in early-stage patients. In tumor tissues, the positive expressions of EDA in NPC tumor tissues were shown to be correlated with the differentiation degrees of cancer cells and lymph node metastases. Additionally, the expression of EDA is positively correlated with the expression of antiapoptotic gene (Bcl2), but negatively correlated with the expressions of apoptotic genes (cleaved caspase-3, cleaved caspase-9, cleaved PARP). In vitro, EDA-silenced NPC cells CNE-2 shows substantially enhanced radiosensitivity with lower colony survival and more apoptosis in response to radiation. In vivo, EDA-silenced xenografts were more sensitive to radiation. At the molecular level, FAK/Akt/JNK signaling was demonstrated to be inactivated in EDA-silenced CNE-2 cells.
EDA strongly affected the radiosensitivity of NPC cells. FAK/Akt/JNK signaling was found to be a potential signaling mediating EDA function.
纤连蛋白额外结构域 A（EDA）已知在恶性肿瘤的血管生成、淋巴管生成和转移中发挥重要作用。本研究探讨了 EDA 对鼻咽癌（NPC）放射抵抗潜能的影响。
通过酶联免疫吸附试验和免疫组织化学检测 NPC 患者血液样本和肿瘤组织中的 EDA 表达水平。通过集落存活试验检测放射敏感性。通过流式细胞术测定细胞凋亡。通过 Western blot 测定 EDA、裂解的半胱天冬酶 9、裂解的半胱天冬酶 3、裂解的多聚（ADP-核糖）聚合酶、Bcl-2 的表达以及磷酸化 FAK、Akt 和 JNK 的水平。使用异种移植来确认 EDA 在体内对放射敏感性的影响。
晚期 NPC 患者血液样本中的 EDA 水平明显高于早期患者。在肿瘤组织中，NPC 肿瘤组织中 EDA 的阳性表达与癌细胞的分化程度和淋巴结转移有关。此外，EDA 的表达与抗凋亡基因（Bcl2）的表达呈正相关，与凋亡基因（裂解的半胱天冬酶-3、裂解的半胱天冬酶-9、裂解的多聚（ADP-核糖）聚合酶）的表达呈负相关。在体外，沉默 EDA 的 NPC 细胞 CNE-2 在受到辐射后，集落存活降低，细胞凋亡增加，表现出明显增强的放射敏感性。在体内，沉默 EDA 的异种移植对辐射更敏感。在分子水平上，沉默 EDA 的 CNE-2 细胞中 FAK/Akt/JNK 信号被证明被失活。
EDA 强烈影响 NPC 细胞的放射敏感性。FAK/Akt/JNK 信号被认为是介导 EDA 功能的潜在信号。
