Enhanced TLR4 Expression on Colon Cancer Cells After Chemotherapy Promotes Cell Survival and Epithelial-Mesenchymal Transition Through Phosphorylation of GSK3β.
Enhanced TLR4 Expression on Colon Cancer Cells After Chemotherapy Promotes Cell Survival and Epithelial-Mesenchymal Transition Through Phosphorylation of GSK3β.
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发表时间：
2016-07
影响因子：
2
通讯作者：
Y. Chung;Daejin Kim
中科院分区：
文献类型：
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作者：
Y. Chung;Daejin Kim
在大多数癌细胞系中，磷脂酰肌醇3-激酶（PI 3 K）/蛋白激酶B（AKT）对糖原合成酶激酶3β（GSK 3 β）的磷酸化或用小分子抑制剂抑制GSK 3 β可减弱细胞存活和增殖并增加细胞凋亡。在这项研究中，我们研究了在药物处理的结肠癌细胞作为化疗后癌细胞的模型中，通过增强toll样受体4（TLR 4）表达而激活的磷酸化GSK 3 β的作用。材料与方法通过实时荧光定量聚合酶链反应（PCR）和免疫印迹法测定TLR 4刺激对药物暴露的结肠癌细胞转移和凋亡的影响。结果尽管奥沙利铂和5-氟尿嘧啶处理后诱导了细胞凋亡，但脂多糖（LPS）刺激通过增加药物处理的癌细胞中的TLR 4，通过上调抗凋亡相关的B细胞淋巴瘤2（BCL 2）家族蛋白[X连锁凋亡抑制蛋白（XIAP），BCL 2，和存活素]和耐药蛋白[多药耐药蛋白1（MDR 1）、多药耐药相关蛋白（MRP）1/2/3]。在药物处理的癌细胞中，LPS介导的信号传导增加了磷酸化GSK 3 β、细胞外信号调节激酶（ERK）和活化B细胞核因子κ轻链增强子（NF-κB）的p65亚基的表达。GSK 3 β的药理学抑制（使用SB 216763）减少了GSK 3 β的磷酸化，重新激活了caspase依赖性细胞凋亡，并阻断了LPS刺激的药物处理细胞中癌症干细胞标志物的表达和侵袭特征。此外，ERK特异性抑制剂PD 98059触发了TLR 4激活的药物暴露的结肠癌细胞的凋亡，而对上皮-间质转化标志物的表达或GSK 3 β磷酸化没有影响。结论TLR 4诱导的GSK 3 β和ERK磷酸化独立调控化疗后结肠癌细胞的存活及GSK 3 β和ERK的调节，TLR 4可能是降低结肠癌耐药和转移的重要靶点。
BACKGROUND Phosphorylation of glycogen synthase kinase 3β (GSK3β) by phosphatidyl-inositide 3-kinase (PI3K)/protein kinase B (AKT) or inhibition of GSK3β with small-molecule inhibitor attenuates cell survival and proliferation and increases apoptosis in most cancer cell lines. In this study, we investigated the role of phosphorylated GSK3β activated by enhanced toll-like receptor 4 (TLR4) expression in drug-treated colon cancer cells as a model of post-chemotherapy cancer cells. MATERIALS AND METHODS The effect of TLR4 stimulation on metastasis and apoptosis in drug-exposed colon cancer cells was determined by real-time polymerase chain reaction (PCR) and immunoblotting. RESULTS Despite the induction of apoptosis after treatment with oxaliplatin and 5-fluorouracil, lipopolysaccharide (LPS) stimulation via increased TLR4 in drug-treated cancer cells effectively inhibited apoptosis through up-regulation of expression of anti-apoptosis-related B-cell lymphoma 2 (BCL2) family proteins [X-linked inhibitor of apoptosis protein (XIAP), BCL2, and survivin] and drug-resistance proteins [multidrug-resistance protein 1 (MDR1), multidrug resistance-associated protein (MRP)1/2/3]. LPS-mediated signaling in drug-treated cancer cells elevated the expression of phosphorylated GSK3β, extracellular signal-regulated kinase (ERK), and the p65 subunit of nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-κB). Pharmacological inhibition of GSK3β (using SB216763) reduced phosphorylation of GSK3β, re-activated caspase-dependent apoptosis, and blocked the expression of cancer stem cell markers and invasive characteristics in LPS-stimulated drug-treated cells. In addition, the ERK-specific inhibitor, PD98059, triggered the apoptosis of TLR4-activated drug-exposed colon cancer cells, whereas there was no effect on the expression of epithelial-mesenchymal transition markers or GSK3β phosphorylation. CONCLUSION These results suggest that TLR4-induced GSK3β and ERK phosphorylation independently controls cancer cell survival and regulation of GSK3β and ERK after chemotherapy, making TLR4 a critical target for reducing drug resistance and metastasis in patients with colon cancer.