Slusser-Nore Andrea, Garrett Scott H, Zhou Xu Dong, Sens Donald A, Sens Mary Ann, Somji Seema
Department of Pathology, University of North Dakota, School of Medicine and Health Sciences, 1301 N. Columbia Road, Stop 9037, Grand Forks, ND 58202, United States.
Toxicol Appl Pharmacol. 2017 Sep 15;331:41-53. doi: 10.1016/j.taap.2017.05.007. Epub 2017 May 10.
Urothelial cancers have an environmental etiological component, and previous studies from our laboratory have shown that arsenite (As) can cause the malignant transformation of the immortalized urothelial cells (UROtsa), leading to the expression of keratin 6 (KRT6). The expression of KRT6 in the parent UROtsa cells can be induced by the addition of epidermal growth factor (EGF). Tumors formed by these transformed cells have focal areas of squamous differentiation that express KRT6. The goal of this study was to investigate the mechanism involved in the upregulation of KRT6 in urothelial cancers and to validate that the As-transformed UROtsa cells are a model of urothelial cancer. The results obtained showed that the parent and the As-transformed UROtsa cells express EGFR which is phosphorylated with the addition of epidermal growth factor (EGF) resulting in an increased expression of KRT6. Inhibition of the extracellular-signal regulated kinases (ERK1/2) pathway by the addition of the mitogen-activated protein kinase kinase 1 (MEK1) and MEK2 kinase inhibitor U0126 resulted in a decrease in the phosphorylation of ERK1/2 and a reduced expression of KRT6. Immuno-histochemical analysis of the tumors generated by the As-transformed isolates expressed EGFR and tumors formed by two of the transformed isolates expressed the phosphorylated form of EGFR. These results show that the expression of KRT6 is regulated at least in part by the ERK1/2 pathway and that the As-transformed human urothelial cells have the potential to serve as a valid model to study urothelial carcinomas.
尿路上皮癌具有环境病因学成分，我们实验室之前的研究表明，亚砷酸盐（As）可导致永生化尿路上皮细胞（UROtsa）发生恶性转化，进而导致角蛋白6（KRT6）的表达。在亲本UROtsa细胞中，添加表皮生长因子（EGF）可诱导KRT6的表达。这些转化细胞形成的肿瘤具有表达KRT6的鳞状分化灶。本研究的目的是探讨尿路上皮癌中KRT6上调所涉及的机制，并验证As转化的UROtsa细胞是否为尿路上皮癌的模型。所得结果表明，亲本和As转化的UROtsa细胞均表达表皮生长因子受体（EGFR），添加表皮生长因子（EGF）后EGFR发生磷酸化，导致KRT6表达增加。添加丝裂原活化蛋白激酶激酶1（MEK1）和MEK2激酶抑制剂U0126抑制细胞外信号调节激酶（ERK1/2）途径，导致ERK1/2磷酸化减少，KRT6表达降低。对As转化分离株产生的肿瘤进行免疫组织化学分析，结果显示肿瘤表达EGFR，其中两个转化分离株形成的肿瘤表达磷酸化形式的EGFR。这些结果表明，KRT6的表达至少部分受ERK1/2途径调控，并且As转化的人尿路上皮细胞有潜力作为研究尿路上皮癌的有效模型。
