Sawanyawisuth Kanlayanee, Tantapotinan Nattawat, Wongkham Chaisiri, Riggins Gregory J, Kraiklang Ratthaphol, Wongkham Sopit, Puapairoj Anucha
Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
Department of Neurosurgery, School of Medicine, Johns Hopkins University, Baltimore, USA.
Ann Hepatol. 2016 Jan-Feb;15(1):71-81. doi: 10.5604/16652681.1184223.
Trophoblast cell surface antigen 2 (TROP2) or tumor-associated calcium signal transducer 2 (TACSTD2) is a 36-kDa type I transmembrane glycoprotein and exerts dual functions as an oncogene and tumor suppressor in cancer cells. In this study, we investigated the expression and functions of TROP2 in liver fluke-associated cholangiocarcinoma (CCA).
TROP2 expression in 85 CCA tissues was detected by using immunohistochemistry. The methylation status of TROP2 promoter was studied in 15 matched pairs of normal and CCA formalin fixed paraffin embedded (FFPE) tissues using the bisulfite genomic sequencing (BGS) method. The functions of TROP2 on cancer cell behavior were investigated using siRNA in CCA cell lines. Proliferation, migration and invasion assays were performed. A PCR array was used to evaluate the impact of TROP2 knockdown on the gene expression profiles.
TROP2 was highly expressed in all normal bile duct epithelia, but significantly down-regulated in CCA cells. Sixty percent of CCA revealed promoter hypermethylation compared to the corresponding adjacent normal tissues. TROP2 knockdown significantly enhanced the proliferation and migration in CCA cell lines, and altered the expressions of MARCK, EMP1 and FILIP1L.
We provide new evidence that TROP2 is epigenetically down-regulated and operates as a negative regulator of cell proliferation and migration in liver fluke-associated CCA.
滋养层细胞表面抗原2（TROP2）或肿瘤相关钙信号转导蛋白2（TACSTD2）是一种36 kDa的I型跨膜糖蛋白，在癌细胞中发挥癌基因和肿瘤抑制基因的双重功能。在本研究中，我们调查了TROP2在肝吸虫相关胆管癌（CCA）中的表达及功能。
采用免疫组织化学检测85例CCA组织中TROP2的表达。使用亚硫酸氢盐基因组测序（BGS）方法研究15对匹配的正常和CCA福尔马林固定石蜡包埋（FFPE）组织中TROP2启动子的甲基化状态。在CCA细胞系中使用小干扰RNA（siRNA）研究TROP2对癌细胞行为的作用。进行增殖、迁移和侵袭实验。使用PCR芯片评估TROP2基因敲低对基因表达谱的影响。
TROP2在所有正常胆管上皮中高表达，但在CCA细胞中显著下调。与相应的相邻正常组织相比，60%的CCA显示启动子高甲基化。TROP2基因敲低显著增强了CCA细胞系的增殖和迁移，并改变了MARCK、EMP1和FILIP1L的表达。
我们提供了新的证据，表明TROP2在表观遗传上被下调，并在肝吸虫相关的CCA中作为细胞增殖和迁移的负调节因子发挥作用。
