Ding Yan, Boguslawski Elissa A, Berghuis Bree D, Young John J, Zhang Zhongfa, Hardy Kim, Furge Kyle, Kort Eric, Frankel Arthur E, Hay Rick V, Resau James H, Duesbery Nicholas S
Laboratory of Cancer and Developmental Cell Biology, Van Andel Research Institute, Grand Rapids, MI 49503, USA.
Mol Cancer Ther. 2008 Mar;7(3):648-58. doi: 10.1158/1535-7163.MCT-07-2229. Epub 2008 Mar 4.
We hypothesized that signaling through multiple mitogen-activated protein kinase (MAPK) kinase (MKK) pathways is essential for the growth and vascularization of soft-tissue sarcomas, which are malignant tumors derived from mesenchymal tissues. We tested this using HT-1080, NCI, and Shac fibrosarcoma-derived cell lines and anthrax lethal toxin (LeTx), a bacterial toxin that inactivates MKKs. Western blots confirmed that LeTx treatment reduced the levels of phosphorylated extracellular signal-regulated kinase and p38 MAPK in vitro. Although short treatments with LeTx only modestly affected cell proliferation, sustained treatment markedly reduced cell numbers. LeTx also substantially inhibited the extracellular release of angioproliferative factors including vascular endothelial growth factor, interleukin-8, and basic fibroblast growth factor. Similar results were obtained with cell lines derived from malignant fibrous histiocytomas, leiomyosarcomas, and liposarcomas. In vivo, LeTx decreased MAPK activity and blocked fibrosarcoma growth. Growth inhibition correlated with decreased cellular proliferation and extensive necrosis, and it was accompanied by a decrease in tumor mean vessel density as well as a reduction in serum expression of angioproliferative cytokines. Vital imaging using high-resolution ultrasound enhanced with contrast microbubbles revealed that the effects of LeTx on tumor perfusion were remarkably rapid (<24 h) and resulted in a marked reduction of perfusion within the tumor but not in nontumor tissues. These results are consistent with our initial hypothesis and lead us to propose that MKK inhibition by LeTx is a broadly effective strategy for targeting neovascularization in fibrosarcomas and other similar proliferative lesions.
我们推测，通过多种丝裂原活化蛋白激酶（MAPK）激酶（MKK）信号通路对于软组织肉瘤的生长和血管生成至关重要，软组织肉瘤是源自间充质组织的恶性肿瘤。我们使用HT-1080、NCI和Shac纤维肉瘤衍生的细胞系以及炭疽致死毒素（LeTx，一种可使MKK失活的细菌毒素）对此进行了测试。蛋白质免疫印迹法证实，LeTx处理在体外降低了磷酸化细胞外信号调节激酶和p38 MAPK的水平。虽然短时间使用LeTx仅适度影响细胞增殖，但持续处理显著减少了细胞数量。LeTx还大幅抑制了包括血管内皮生长因子、白细胞介素-8和碱性成纤维细胞生长因子在内的血管增殖因子的细胞外释放。从恶性纤维组织细胞瘤、平滑肌肉瘤和脂肪肉瘤衍生的细胞系也得到了类似结果。在体内，LeTx降低了MAPK活性并阻断了纤维肉瘤的生长。生长抑制与细胞增殖减少和广泛坏死相关，同时伴有肿瘤平均血管密度降低以及血管增殖细胞因子血清表达减少。使用对比微泡增强的高分辨率超声进行的活体成像显示，LeTx对肿瘤灌注的影响非常迅速（<24小时），导致肿瘤内灌注显著减少，但非肿瘤组织不受影响。这些结果与我们最初的假设一致，并使我们提出，LeTx抑制MKK是一种广泛有效的策略，可用于靶向纤维肉瘤和其他类似增殖性病变中的新生血管形成。
