Expression data from MTDH knockdown in the Hec50co endometrial cancer cell line

Understanding the molecular underpinnings of chemoresistance is vital to design therapies to restore chemosensitivity. In particular, metadherin (MTDH) has been demonstrated to have a critical role in chemoresistance. Over-expression of MTDH has recently been implicated in poor clinical outcome in breast cancer, neroblastoma, hepatocellular carcinoma and prostate cancer. In this present study, we focused on the therapeutic benefit of MTDH depletion to restore sensitivity to cell death mediated by a combinatorial therapy of tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL), which promotes death of cancerous cells of the human reproductive tract, and histone deacetylase (HDAC) inhibitors, which have been shown to increase sensitivity of cancer cells to TRAIL-induced apoptosis. Our data indicate that depletion of MTDH in endometrial cancer cells results in sensitization of cells that were previously resistant to cell death mediated by combinatorial treatment with TRAIL and HDAC inhibitor LBH589. MTDH was found to be involved in G2/M checkpoint regulation in response to LBH589 alone or LBH589 in combination with TRAIL, suggesting that MTDH functions at the cell cycle checkpoint to accomplish resistance.Using microarray technology, we identified 57 downstream target genes of MTDH, including Calbindin 1 and Galectin 1, which may contribute to MTDH-mediated resistance to combinatorial TRAIL and HDAC inhibitor targeted therapy. Inhibition of PDK1,AKT phosphorylation and increase Bim expression and XIAP degradation may result in sensitivity to cell death induction in MTDH depleted Hec50co cells by TRAIL and LBH 589 combination treatment. These findings indicate that depletion of MTDH is a potentially novel avenue for effective cancer therapy. The microarray was performed on three biological triplicates as well as three experimental triplictes of stable knockdown and control cells. MTDH was knocked down using a shRNA.

阐明化疗耐药的分子机制，对于开发恢复化疗敏感性的治疗策略至关重要。其中，元黏附蛋白（metadherin, MTDH）已被证实对化疗耐药发挥关键调控作用。近期研究发现，MTDH过表达与乳腺癌、神经母细胞瘤、肝细胞癌及前列腺癌的不良临床结局相关。本研究聚焦于敲低MTDH以恢复细胞死亡敏感性的治疗价值，该策略针对的是肿瘤坏死因子α相关凋亡诱导配体（tumor necrosis factor-alpha-related apoptosis-inducing ligand, TRAIL）与组蛋白去乙酰化酶（histone deacetylase, HDAC）抑制剂的联合疗法：TRAIL可诱导人类生殖道癌细胞死亡，而HDAC抑制剂已被证实可增强癌细胞对TRAIL诱导凋亡的敏感性。本研究数据显示，在子宫内膜癌细胞中敲低MTDH，可使原本对TRAIL与HDAC抑制剂LBH589联合治疗诱导的细胞死亡产生耐药的细胞恢复敏感性。研究发现，MTDH参与了单独使用LBH589或LBH589联合TRAIL处理时的G2/M细胞周期检查点调控，提示MTDH通过作用于细胞周期检查点介导耐药性的产生。本研究通过微阵列技术（microarray technology）鉴定出57个MTDH的下游靶基因，其中包括钙结合蛋白1（Calbindin 1）和半乳糖凝集素1（Galectin 1），这些基因可能参与了MTDH介导的对TRAIL与HDAC抑制剂联合靶向治疗的耐药过程。抑制磷酸肌醇依赖性蛋白激酶1（PDK1）、蛋白激酶B（AKT）、Bcl-2相互作用蛋白（Bim）并促进X连锁凋亡抑制蛋白（XIAP）降解，可使MTDH敲低的Hec50co细胞在TRAIL与LBH589联合治疗下恢复对细胞死亡诱导的敏感性。上述研究结果表明，敲低MTDH有望成为一种全新的有效癌症治疗途径。本研究的微阵列实验设置了3次生物学重复与3次实验重复，分别针对稳定敲低MTDH的细胞及对照细胞。MTDH的敲低通过短发夹RNA（shRNA）实现。