MicroRNA regulation of glucocorticoid-induced autophagy and progression of pancreatic ductal adenocarcinoma

胰腺导管腺癌(PDA)是最具侵袭性的恶性肿瘤之一，预后差。糖皮质激素(GC)，如地塞米松(DEX)，作为限制副作用和缓解原因的联合治疗。越来越多的证据表明，GCs可诱导涉及PDA的上皮性肿瘤细胞的进展和治疗耐药。这类似于其他类固醇激素，如雌激素或雄激素，其受体在乳腺癌和前列腺癌中因治疗原因而被阻断。2003年，我们小组在体内首次报道了药理剂量的地塞米松对肺癌和宫颈癌细胞的化疗耐药。与此同时，这些数据得到了其他几位研究人员的证实，并得到了患者研究的支持。我们的最新数据表明，糖皮质激素受体和蛋白激酶信号通路激活转化生长因子β，从而介导治疗耐药和动脉粥样硬化的上皮-间充质转化。我们未发表的结果表明，自噬和GC诱导的microRNA(MiRNA)信号也参与其中。通过miRNA阵列分析、生物信息学评价和电子计算预测，我们确定miR-132、miR-378a-3p、miR-10b-5p及其靶基因转化生长因子β、atg12、ras/ERK和JNK/AP-1为关键功能基因。本课题的目的是对GC诱导的miRNA信号进行分子分析，验证最重要的miRNAs及其靶基因，研究GC诱导的EMT和自噬在恶性进展中的作用。我们将检查(1)不仅地塞米松，而且其他常用的GC药物是否诱导PDA进展，(2)在Whiple OP之前的GC预给药是否影响候选miRNAs及其靶基因在患者组织中的表达，(3)候选miRNA及其靶基因在功能上参与地塞米松诱导的自噬和EMT，(4)地塞米松诱导的自噬和EMT是交叉调控的，(5)最强的miRNA候选及其S靶基因在使用肿瘤异种移植模型的体内是有效的。这个项目有助于更好地理解复杂的分子机制，GC药物通过这些机制在PDA中介导有益但也有害的影响。常规处方的GC药物的参与和患者组织的检查强调了翻译特征和临床相关性。考虑到GCs经常被使用，而且严重的压力、慢性胰腺炎、抑郁、富含蛋白质的膳食和急性吸烟会增加内源性GC水平，预期的结果也可能有助于了解胰腺癌的发展，以及其他上皮性肿瘤实体的发展。

Pancreatic ductal adenocarcinoma (PDA) is one of the most aggressive malignancies with poor prognosis. Glucocorticoids (GCs), such as dexamethasone (DEX), are administered as co-treatment to limit side effects and for palliative reasons. Accumulating evidence indicates that GCs induce progression and therapy resistance of epithelial tumor cells involving PDA. This is similar to other steroid hormones, such as estrogen or androgen, whose receptors are blocked for therapeutic reasons in breast and prostate cancer. The first in vivo report about the induction of chemotherapy resistance by pharmacological doses of DEX in a lung and cervical cancer cell line came from our group in 2003. Meanwhile these data were confirmed by several other researchers and are supported by patient studies. Our latest data demonstrate that signaling by glucocorticoid receptor and kinases activate TGFβ, which mediates therapy resistance and epithelial-mesenchymal transition (EMT) in PDA. Our unpublished results indicate that autophagy and GC-induced microRNA (miRNA) signaling are also involved. By miRNA array analysis, bioinformatic evaluation and in silico computational prediction we identified miR-132, miR-378a-3p, miR-10b-5p, and their target genes TGFβ, ATG12, RAS/ERK and JNK/AP-1 as key players.The aim of the requested project is the molecular analysis of GC-induced miRNA signaling, the verification of the most significant miRNAs with their target genes and to examine the function of GC-induced EMT and autophagy in malignant progression. We will examine whether (1) not only DEX, but also other commonly prescribed GC medicaments induce PDA progression, (2) GC pre-medication prior to Whipple OP influences the expression of candidate miRNAs and their target genes in patient tissue, (3) the miRNA candidates and their target genes are functionally involved in DEX-induced autophagy and EMT, (4) DEX-induced autophagy and EMT are cross-regulated, and (5) the strongest miRNA candidate and it´s target gene are effective in vivo using tumorxenograft models. This project contributes to a better understanding of the complex molecular mechanisms, by which GC medicaments mediate beneficial but also harmful effects in PDA. The involvement of commonly prescribed GC medicaments and the examination of patient tissues underline the translational character and the clinical relevance. Considering that GCs are frequently used and that severe stress, chronic pancreatitis, depression, protein-rich meals, and acute smoking raise endogenous GC levels, the expected results may also contribute to understand the development of pancreatic cancer, but also of other epithelial tumor entities.