Department of Pathology, The First Teaching Hospital of Zhengzhou University, Basic Medical College, Zhengzhou University, Zhengzhou, Henan Province, China.
PLoS One. 2013;8(2):e56141. doi: 10.1371/journal.pone.0056141. Epub 2013 Feb 7.
Notch signaling involves the processes that govern cell proliferation, cell fate decision, cell differentiation and stem cell maintenance. Due to its fundamental role in stem cells, it has been speculated during the recent years that Notch family may have critical functions in cancer stem cells or cancer cells with a stem cell phenotype, therefore playing an important role in the process of oncogenesis. In this study, expression of Notch family in KYSE70, KYSE140 and KYSE450 squamous esophageal cancer cell lines and virus transformed squamous esophageal epithelial cell line Het-1A was examined by quantitative RT-PCR. Compared to the Het-1A cells, higher levels of Nocth1 and Notch3 expression in the cancer cell lines were identified. Due to the finding that NOTCH3 mainly mediates squamous cell differentiation, NOTCH1 expression was further studied in these cell lines. By Western blot analyses, the KYSE70 cell line which derived from a poorly differentiated tumor highly expressed Notch1, and the Notch1 expression in this cell line was hypoxia inducible, while the KYSE450 cell line which derived from a well differentiated tumor was always negative for Notch1, even in hypoxia. Additional studies demonstrated that the KYSE70 cell line was more 5-FU resistant than the KYSE450 cell line and such 5-FU resistance is correlated to Notch1 expression verified by Notch1 knockdown experiments. In clinical samples, Notch1 protein expression was detected in the basal cells of human esophagus epithelia, and its expression in squamous cell carcinomas was significantly associated with higher pathological grade and shorter overall survival. We conclude that Notch1 expression is associated with cell aggressiveness and 5-FU drug resistance in human esophageal squamous cell carcinoma cell lines in vitro and is significantly associated with a poor survival in human esophageal squamous cell carcinomas.
Notch 信号通路涉及细胞增殖、细胞命运决定、细胞分化和干细胞维持等过程。由于其在干细胞中的基本作用，近年来有人推测 Notch 家族可能在癌症干细胞或具有干细胞表型的癌细胞中具有关键功能，因此在致癌过程中发挥重要作用。在这项研究中，通过定量 RT-PCR 检测了 Notch 家族在 KYSE70、KYSE140 和 KYSE450 食管鳞状癌细胞系和病毒转化的食管鳞状上皮细胞系 Het-1A 中的表达。与 Het-1A 细胞相比，在癌细胞系中发现 Notch1 和 Notch3 的表达水平较高。由于发现 NOTCH3 主要介导鳞状细胞分化，因此进一步研究了这些细胞系中的 NOTCH1 表达。通过 Western blot 分析，源自低分化肿瘤的 KYSE70 细胞系高度表达 Notch1，并且该细胞系中的 Notch1 表达可被缺氧诱导，而源自高分化肿瘤的 KYSE450 细胞系始终为 Notch1 阴性，即使在缺氧条件下也是如此。进一步的研究表明，KYSE70 细胞系比 KYSE450 细胞系对 5-FU 更具有耐药性，并且这种 5-FU 耐药性与 Notch1 表达相关，这一结论通过 Notch1 敲低实验得到了验证。在临床样本中，Notch1 蛋白在人食管上皮的基底细胞中被检测到，其在鳞状细胞癌中的表达与较高的病理分级和较短的总生存期显著相关。我们的结论是，Notch1 表达与体外人食管鳞状细胞癌细胞系的细胞侵袭性和 5-FU 耐药性相关，并且与人类食管鳞状细胞癌的不良预后显著相关。
