Chen Chun-Liang, Loy Abbey, Cen Ling, Chan Christina, Hsieh Fu-Chuan, Cheng Gong, Wu Bryant, Qualman Stephen J, Kunisada Keita, Yamauchi-Takihara Keiko, Lin Jiayuh
Center for Childhood Cancer, Columbus Children's Research Institute and Department of Pediatrics, The Ohio State University, Columbus, OH 43205, USA.
BMC Cancer. 2007 Jun 28;7:111. doi: 10.1186/1471-2407-7-111.
Stat3 has been classified as a proto-oncogene and constitutive Stat3 signaling appears to be involved in oncogenesis of human cancers. However, whether constitutive Stat3 signaling plays a role in the survival and growth of osteosarcomas, rhabdomyosarcomas, and soft-tissue sarcomas is still unclear.
To examine whether Stat3 is activated in osteosarcomas, rhabdomyosarcomas and other soft-tissue sarcomas we analyzed sarcoma tissue microarray slides and sarcoma cell lines using immunohistochemistry and Western blot analysis, respectively, with a phospho-specific Stat3 antibody. To examine whether the activated Stat3 pathway is important for sarcoma cell growth and survival, adenovirus-mediated expression of a dominant-negative Stat3 (Y705F) and a small molecule inhibitor (termed STA-21) were used to inhibit constitutive Stat3 signaling in human sarcoma cell lines expressing elevated levels of Stat3 phosphorylation. Cell viability was determined by MTT assays and induction of apoptosis was analyzed by western blotting using antibodies that specifically recognize cleaved caspases-3, 8, and 9.
Stat3 phosphorylation is elevated in 19% (21/113) of osteosarcoma, 27% (17/64) of rhabdomyosarcoma, and 15% (22/151) of other soft-tissue sarcoma tissues as well as in sarcoma cell lines. Expression of the dominant-negative Stat3 and treatment of STA-21 inhibited cell viability and growth and induced apoptosis through caspases 3, 8 and 9 pathways in human sarcoma cell lines expressing elevated levels of phosphorylated Stat3.
This study demonstrates that Stat3 phosphorylation is elevated in human rhabdomyosarcoma, osteosarcomas and soft-tissue sarcomas. Furthermore, the activated Stat3 pathway is important for cell growth and survival of human sarcoma cells.
Stat3已被归类为原癌基因，持续性Stat3信号似乎参与人类癌症的发生。然而，持续性Stat3信号是否在骨肉瘤、横纹肌肉瘤和软组织肉瘤的存活与生长中发挥作用仍不清楚。
为检测Stat3在骨肉瘤、横纹肌肉瘤和其他软组织肉瘤中是否被激活，我们分别使用免疫组织化学和蛋白质印迹分析，采用磷酸化特异性Stat3抗体，分析肉瘤组织微阵列玻片和肉瘤细胞系。为检测激活的Stat3通路对肉瘤细胞生长和存活是否重要，我们使用腺病毒介导的显性负性Stat3（Y705F）表达和小分子抑制剂（称为STA-21），抑制Stat3磷酸化水平升高的人肉瘤细胞系中的持续性Stat3信号。通过MTT试验测定细胞活力，使用特异性识别切割的半胱天冬酶-3、8和9的抗体，通过蛋白质印迹分析凋亡诱导情况。
在19%（21/113）的骨肉瘤、27%（17/64）的横纹肌肉瘤、15%（22/151）的其他软组织肉瘤组织以及肉瘤细胞系中，Stat3磷酸化水平升高。显性负性Stat3的表达和STA-21处理，抑制了Stat3磷酸化水平升高的人肉瘤细胞系的细胞活力和生长，并通过半胱天冬酶3、8和9通路诱导凋亡。
本研究表明，Stat3磷酸化在人横纹肌肉瘤、骨肉瘤和软组织肉瘤中升高。此外，激活的Stat3通路对人肉瘤细胞的生长和存活很重要。
