Department of Biological Sciences, Pusan National University, Pusan, Korea.
Radiat Res. 2013 Jan;179(1):69-75. doi: 10.1667/RR3091.1. Epub 2012 Nov 26.
Radiotherapy is commonly used in treating many kinds of cancers that cannot be cured by other therapeutic strategies. However, radiation-induced fibrosis in the treatment of intrahepatic cancer is a major obstacle. Hedgehog pathway is known to regulate the fibrotic process and proliferation of progenitor cells. Hedgehog ligands act as a profibrotic factor and hedgehog-responsive cells undergo epithelial-to-mesenchymal transition (EMT), eventually contributing to the fibrogenic process. Herein, we investigated whether the hedgehog pathway was associated with radiation-induced hepatic fibrosis. Female mice were irradiated with a single dose of 20 Gy and were sacrificed 1 week postirradiation, to obtain the livers for biochemical and histological analysis. Hematoxylin and eosin and Sirius Red staining were used in evaluating liver morphology and fibrosis, respectively. Immunochemical staining for active caspase 3 and CD44 was used to examine the repair response of the irradiated livers. Immunoblot analysis was performed to detect the expression of hedgehog molecules and fibrogenic markers. Fat accumulation in hepatocytes and increased apoptosis were observed in liver sections from mice treated with radiation. Expression of hedgehog ligand, Indian hedgehog, and hedgehog target gene, Gli2, were significantly up-regulated in the liver of mice treated with radiation. Levels of transforming growth factor-β (inducer of fibrosis) and α-smooth muscle actin (marker of myofibroblastic hepatic stellate cells) were also greatly increased in the damaged liver compared to the normal liver. The EMT marker, laminin-β3, showed a great increase, whereas EMT inhibitor, bmp7, was significantly decreased in mouse liver postirradiation. Furthermore, CD44-positive progenitors were shown to accumulated in the injured liver. These results suggest that increased expression of hedgehog signaling promotes proliferation of myofibroblastic hepatic stellate cells and progenitors, and thereby contributes to the repair response after irradiation.
放射疗法常用于治疗无法通过其他治疗策略治愈的多种癌症。然而，在治疗肝内癌症时，辐射诱导的纤维化是一个主要障碍。 hedgehog 通路被认为可以调节纤维化过程和祖细胞的增殖。 hedgehog 配体作为促纤维化因子起作用， hedgehog 反应性细胞经历上皮-间充质转化（EMT），最终导致纤维生成过程。在此，我们研究了 hedgehog 通路是否与辐射诱导的肝纤维化有关。雌性小鼠接受单次 20 Gy 照射，并在照射后 1 周处死，以获得用于生化和组织学分析的肝脏。苏木精和伊红染色和 Sirius Red 染色分别用于评估肝脏形态和纤维化。免疫组织化学染色用于检测活性 caspase 3 和 CD44 以检查照射肝脏的修复反应。免疫印迹分析用于检测 hedgehog 分子和纤维生成标记物的表达。在接受辐射的小鼠的肝脏切片中观察到肝细胞脂肪堆积和细胞凋亡增加。在接受辐射的小鼠肝脏中， hedgehog 配体、印度 hedgehog 和 hedgehog 靶基因 Gli2 的表达明显上调。与正常肝脏相比，转化生长因子-β（纤维化诱导剂）和α-平滑肌肌动蛋白（肌成纤维细胞肝星状细胞的标志物）的水平也大大增加。 EMT 标记物 laminin-β3 明显增加，而 EMT 抑制剂 bmp7 在小鼠肝脏照射后明显减少。此外，在受损的肝脏中显示出 CD44 阳性祖细胞的积累。这些结果表明， hedgehog 信号的表达增加促进了肌成纤维细胞肝星状细胞和祖细胞的增殖，从而有助于照射后的修复反应。
