Findlay Victoria J, Wang Cindy, Nogueira Lourdes M, Hurst Katie, Quirk Daniel, Ethier Stephen P, Staveley O'Carroll Kevin F, Watson Dennis K, Camp E Ramsay
Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina. Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina.
Department of Surgery, Medical University of South Carolina, Charleston, South Carolina.
Mol Cancer Ther. 2014 Nov;13(11):2713-26. doi: 10.1158/1535-7163.MCT-14-0207. Epub 2014 Sep 23.
Epithelial-to-mesenchymal transition (EMT) has been associated with poor treatment outcomes in various malignancies and is inversely associated with miRNA145 expression. Therefore, we hypothesized that SNAI2 (Slug) may mediate 5-fluorouracil (5FU) chemotherapy resistance through inhibition of miR145 in colorectal cancer and thus represents a novel therapeutic target to enhance current colorectal cancer treatment strategies. Compared with parental DLD1 colon cancer cells, 5FU-resistant (5FUr) DLD1 cells demonstrated features of EMT, including >2-fold enhanced invasion (P < 0.001) and migration, suppressed E-cadherin expression, and 2-fold increased SNAI2 expression. DLD1 and HCT116 cells with stable expression of SNAI2 (DLD1/SNAI2; HCT116/SNAI2) also demonstrated EMT features such as the decreased E-cadherin as well as significantly decreased miR145 expression, as compared with control empty vector cells. On the basis of an miR145 luciferase promoter assay, we demonstrated that SNAI2 repressed activity of the miR145 promoter in the DLD1 and HCT116 cells. In addition, the ectopic expressing SNAI2 cell lines demonstrated decreased 5FU sensitivity, and, conversely, miR145 replacement significantly enhanced 5FU sensitivity. In the parental SW620 colon cancer cell line with high SNAI2 and low miR145 levels, inhibition of SNAI2 directly with short hairpin sequence for SNAI2 and miR145 replacement therapy both decreased vimentin expression and increased in vitro 5FU sensitivity. In pretreatment rectal cancer patient biopsy samples, low miR145 expression levels correlated with poor response to neoadjuvant 5FU-based chemoradiation. These results suggested that the SNAI2:miR145 pathway may represent a novel clinical therapeutic target in colorectal cancer and may serve as a response predictor to chemoradiation therapy.
上皮-间质转化（EMT）与多种恶性肿瘤的不良治疗结果相关，且与miRNA145的表达呈负相关。因此，我们推测SNAI2（Slug）可能通过抑制miR145介导结直肠癌对5-氟尿嘧啶（5FU）的化疗耐药，从而代表一种增强当前结直肠癌治疗策略的新治疗靶点。与亲代DLD1结肠癌细胞相比，5FU耐药（5FUr）的DLD1细胞表现出EMT特征，包括侵袭增强>2倍（P < 0.001）和迁移能力增强、E-钙黏蛋白表达受抑制以及SNAI2表达增加2倍。与对照空载体细胞相比，稳定表达SNAI2的DLD1和HCT116细胞（DLD1/SNAI2；HCT116/SNAI2）也表现出EMT特征，如E-钙黏蛋白减少以及miR145表达显著降低。基于miR145荧光素酶启动子分析，我们证明SNAI2抑制了DLD1和HCT116细胞中miR145启动子的活性。此外，异位表达SNAI2的细胞系对5FU的敏感性降低，相反，miR145替代显著增强了5FU敏感性。在具有高SNAI2和低miR145水平的亲代SW620结肠癌细胞系中，用针对SNAI2的短发夹序列直接抑制SNAI2以及miR145替代疗法均降低了波形蛋白表达并增加了体外5FU敏感性。在直肠癌患者预处理活检样本中，低miR145表达水平与基于5FU的新辅助放化疗反应不佳相关。这些结果表明，SNAI2:miR145通路可能代表结直肠癌的一种新的临床治疗靶点，并可作为放化疗反应的预测指标。
