Biomedical Department of Internal and Specialized Medicine (DiBiMIS), University of Palermo, Palermo, Italy.
Thyroid. 2013 Jul;23(7):829-37. doi: 10.1089/thy.2012.0372. Epub 2013 Jun 21.
Anaplastic thyroid carcinoma (ATC) is a rare and aggressive endocrine tumor with highly undifferentiated morphology. It has been suggested that cancer stem cells (CSCs) might play a central role in ATC. The objectives of this study were (i) to characterize CSCs from ex vivo ATC specimens by investigating the expression of several pluripotent stem cell markers, and (ii) to evaluate in vitro drug resistance modifications after specific CSC transcription factor switch-off.
In ex vivo experiments, eight formalin-fixed, paraffin-embedded ATC specimens were analyzed by reverse-transcription and real-time quantitative PCR and immunohistochemistry. In in vitro experiments using ATC SW1736 cells, the expression levels of OCT-4, NANOG, and ABCG2 and the sensitivity to either cisplatin or doxorubicin were evaluated after silencing.
OCT-4, KLF4, and SOX2 transcription factors and C-KIT and THY-1 stem surface antigens showed variable up-regulation in all ATC cases. The SW1736 cell line was characterized by a high percentage of stem population (10.4±2.1% of cells were aldehyde dehydrogenase positive) and high expression of several CSC markers (SOX2, OCT4, NANOG, C-MYC, and SSEA4). SOX2 silencing down-regulated OCT-4, NANOG, and ABCG2. SOX2 silencing sensitized SW1736 cells, causing a significant cell death increase (1.8-fold) in comparison to control cells with 10 μM cisplatin (93.9±3.4% vs. 52.6±9.4%, p<0.01) and 2.7 fold with 0.5 μM doxorubicin (45.8±9.9% vs. 17.1±3.4% p<0.01). ABCG2 silencing caused increased cell death with both cisplatin (74.9±1.4%) and doxorubicin treatment (74.1±0.1%) vs. no-target-treated cells (respectively, 45.8±1.0% and 48.6±1.0%, p<0.001).
The characterization of CSCs in ATC through the analysis of multiple pluripotent stem cell markers might be useful in identifying cells with a stem-like phenotype capable of resisting conventional chemotherapy. In addition, our data demonstrate that SOX2 switch-off through ABCG2 transporter down-regulation has a major role in overcoming CSC chemotherapy resistance.
间变性甲状腺癌（ATC）是一种罕见且侵袭性的内分泌肿瘤，具有高度未分化的形态。有研究表明，癌症干细胞（CSC）可能在 ATC 中发挥核心作用。本研究的目的是：（i）通过研究几种多能干细胞标志物的表达，对来自体外 ATC 标本的 CSC 进行鉴定；（ii）评估特定 CSC 转录因子失活后体外药物耐药性的改变。
在体外实验中，对 8 例福尔马林固定、石蜡包埋的 ATC 标本进行逆转录和实时定量 PCR 及免疫组织化学分析。在体外实验中，使用 ATC SW1736 细胞，在沉默后评估 OCT-4、NANOG 和 ABCG2 的表达水平和对顺铂或阿霉素的敏感性。
在所有 ATC 病例中，OCT-4、KLF4 和 SOX2 转录因子以及 C-KIT 和 THY-1 干细胞表面抗原均呈不同程度的上调。SW1736 细胞系具有高比例的干细胞群体（10.4±2.1%的细胞为醛脱氢酶阳性）和多种 CSC 标志物（SOX2、OCT4、NANOG、C-MYC 和 SSEA4）的高表达。SOX2 沉默下调 OCT-4、NANOG 和 ABCG2。与对照组细胞相比，SOX2 沉默使 SW1736 细胞对 10 μM 顺铂（93.9±3.4%比 52.6±9.4%，p<0.01）和 0.5 μM 阿霉素（45.8±9.9%比 17.1±3.4%，p<0.01）的敏感性显著增加。ABCG2 沉默使顺铂（74.9±1.4%）和阿霉素处理（74.1±0.1%）的细胞死亡增加，与无靶细胞相比（分别为 45.8±1.0%和 48.6±1.0%，p<0.001）。
通过分析多种多能干细胞标志物对 ATC 中 CSC 的鉴定可能有助于识别具有抵抗常规化疗能力的干细胞样表型细胞。此外，我们的数据表明，通过 ABCG2 转运体下调来关闭 SOX2 在克服 CSC 化疗耐药性方面发挥着重要作用。
