Department of Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Mol Cell Proteomics. 2010 Nov;9(11):2405-13. doi: 10.1074/mcp.M110.000240. Epub 2010 Jul 22.
Leiomyosarcoma is one of the most common mesenchymal tumors. Proteomics profiling analysis by reverse-phase protein lysate array surprisingly revealed that expression of the epithelial marker E-cadherin (encoded by CDH1) was significantly elevated in a subset of leiomyosarcomas. In contrast, E-cadherin was rarely expressed in the gastrointestinal stromal tumors, another major mesenchymal tumor type. We further sought to 1) validate this finding, 2) determine whether there is a mesenchymal to epithelial reverting transition (MErT) in leiomyosarcoma, and if so 3) elucidate the regulatory mechanism responsible for this MErT. Our data showed that the epithelial cell markers E-cadherin, epithelial membrane antigen, cytokeratin AE1/AE3, and pan-cytokeratin were often detected immunohistochemically in leiomyosarcoma tumor cells on tissue microarray. Interestingly, the E-cadherin protein expression was correlated with better survival in leiomyosarcoma patients. Whole genome microarray was used for transcriptomics analysis, and the epithelial gene expression signature was also associated with better survival. Bioinformatics analysis of transcriptome data showed an inverse correlation between E-cadherin and E-cadherin repressor Slug (SNAI2) expression in leiomyosarcoma, and this inverse correlation was validated on tissue microarray by immunohistochemical staining of E-cadherin and Slug. Knockdown of Slug expression in SK-LMS-1 leiomyosarcoma cells by siRNA significantly increased E-cadherin; decreased the mesenchymal markers vimentin and N-cadherin (encoded by CDH2); and significantly decreased cell proliferation, invasion, and migration. An increase in Slug expression by pCMV6-XL5-Slug transfection decreased E-cadherin and increased vimentin and N-cadherin. Thus, MErT, which is mediated through regulation of Slug, is a clinically significant phenotype in leiomyosarcoma.
平滑肌肉瘤是最常见的间叶性肿瘤之一。通过反相蛋白裂解物阵列的蛋白质组学分析令人惊讶地发现，上皮标志物 E-钙黏蛋白（由 CDH1 编码）的表达在一部分平滑肌肉瘤中显著升高。相比之下，E-钙黏蛋白在另一种主要的间叶性肿瘤类型——胃肠道间质瘤中很少表达。我们进一步寻求：1）验证这一发现；2）确定平滑肌肉瘤中是否存在间充质到上皮的逆转转化（MErT）；如果是，3）阐明负责这种 MErT 的调节机制。我们的数据显示，上皮细胞标志物 E-钙黏蛋白、上皮膜抗原、细胞角蛋白 AE1/AE3 和泛细胞角蛋白在组织微阵列上的平滑肌肉瘤肿瘤细胞中经常通过免疫组织化学检测到。有趣的是，E-钙黏蛋白蛋白的表达与平滑肌肉瘤患者的更好生存相关。全基因组微阵列用于转录组学分析，上皮基因表达特征也与更好的生存相关。转录组数据的生物信息学分析显示，在平滑肌肉瘤中 E-钙黏蛋白和 E-钙黏蛋白抑制因子 Slug（SNAI2）的表达呈负相关，通过 E-钙黏蛋白和 Slug 的免疫组织化学染色在组织微阵列上验证了这种负相关。通过 siRNA 敲低 SK-LMS-1 平滑肌肉瘤细胞中的 Slug 表达显著增加了 E-钙黏蛋白；降低了间充质标志物波形蛋白和 N-钙黏蛋白（由 CDH2 编码）；并显著降低了细胞增殖、侵袭和迁移。通过 pCMV6-XL5-Slug 转染增加 Slug 表达会降低 E-钙黏蛋白并增加波形蛋白和 N-钙黏蛋白。因此，通过 Slug 调节的 MErT 是平滑肌肉瘤中具有临床意义的表型。
