Kumar S, Das S, Rachagani S, Kaur S, Joshi S, Johansson S L, Ponnusamy M P, Jain M, Batra S K
Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.
Oncogene. 2015 Sep 10;34(37):4879-89. doi: 10.1038/onc.2014.409. Epub 2014 Dec 22.
Pancreatic cancer (PC) is characterized by aberrant overexpression of mucins that contribute to its pathogenesis. Although the inflammatory cytokines contribute to mucin overexpression, the mucin profile of PC is markedly distinct from that of normal or inflamed pancreas. We postulated that de novo expression of various mucins in PC involves chromatin modifications. Analysis of chromatin modifying enzymes by PCR array identified differential expression of NCOA3 in MUC4-expressing PC cell lines. Immunohistochemistry analysis in tumor tissues from patients and spontaneous mouse models, and microarray analysis following the knockdown of NCOA3 were performed to elucidate its role in mucin regulation and overall impact on PC. Silencing of NCOA3 in PC cell lines resulted in significant downregulation of two most differentially expressed mucins in PC, MUC4 and MUC1 (P<0.01). Immunohistochemistry analysis in PC tissues and metastatic lesions established an association between NCOA3 and mucin (MUC1 and MUC4) expression. Spontaneous mouse model of PC (K-ras(G12D); Pdx-1cre) showed early expression of Ncoa3 during pre-neoplastic lesions. Mechanistically, NCOA3 knockdown abrogated retinoic acid-mediated MUC4 upregulation by restricting MUC4 promoter accessibility as demonstrated by micrococcus nuclease digestion (P<0.05) and chromatin immuno-precipitation analysis. NCOA3 also created pro-inflammatory conditions by upregulating chemokines like CXCL1, 2, 5 and CCL20 (P<0.001). AKT, ubiquitin C, ERK1/2 and NF-κB occupied dominant nodes in the networks significantly modulated after NCOA3 silencing. In addition, NCOA3 stabilized mucins post translationally through fucosylation by FUT8, as the knockdown of FUT8 resulted in the downregulation of MUC4 and MUC1 at protein levels.
胰腺癌(PC)的特征是黏蛋白异常过表达,这对其发病机制有影响。尽管炎性细胞因子会导致黏蛋白过表达,但PC的黏蛋白谱与正常或发炎胰腺的黏蛋白谱明显不同。我们推测PC中各种黏蛋白的从头表达涉及染色质修饰。通过PCR阵列分析染色质修饰酶,发现NCOA3在表达MUC4的PC细胞系中存在差异表达。对患者肿瘤组织和自发小鼠模型进行免疫组织化学分析,并在敲低NCOA3后进行微阵列分析,以阐明其在黏蛋白调节中的作用以及对PC的总体影响。在PC细胞系中沉默NCOA3导致PC中两种差异表达最明显的黏蛋白MUC4和MUC1显著下调(P<0.01)。对PC组织和转移灶的免疫组织化学分析确定了NCOA3与黏蛋白(MUC1和MUC4)表达之间的关联。PC的自发小鼠模型(K-ras(G12D); Pdx-1cre)显示在肿瘤前病变期间Ncoa3早期表达。从机制上讲,如微球菌核酸酶消化(P<0.05)和染色质免疫沉淀分析所示,NCOA3敲低通过限制MUC4启动子的可及性消除了视黄酸介导的MUC4上调。NCOA3还通过上调趋化因子如CXCL1、2、5和CCL20来创造促炎条件(P<0.001)。在NCOA3沉默后,AKT、泛素C、ERK1/2和NF-κB在显著调节的网络中占据主导节点。此外,NCOA3通过FUT8介导的岩藻糖基化在翻译后稳定黏蛋白,因为敲低FUT8导致MUC4和MUC1在蛋白质水平下调。