Abstract 1074: Epigenetic silencing of DACH1 in triple negative breast cancer contributes to the tumorigenesis
Abstract 1074: Epigenetic silencing of DACH1 in triple negative breast cancer contributes to the tumorigenesis
复制标题
摘要 1074：三阴性乳腺癌中 DACH1 的表观遗传沉默有助于肿瘤发生
DOI：
10.1158/1538-7445.am2015-1074
复制
发表时间：
2015
期刊：
影响因子：
11.2
通讯作者：
Kongming Wu
中科院分区：
文献类型：
--
作者：
Q. Chu;N. Han;Yan Dong;Xun Yuan;M. Guo;Hanxiao Xu;Shiying Yu;Kongming Wu
背景：越来越多的证据表明，细胞命运决定因子DACH1具有肿瘤抑制作用。具体地说，在雌激素受体阳性(Lumina)中，DACH1的高表达预示着更长的癌症特异性生存期和无病间隔，以及减少转移形成。我们对2,000多名患者的分析显示，核DACH1表达增加与细胞有丝分裂呈负相关，并预测乳腺癌患者40个月的生存优势。但是，内源性DACH1在肿瘤起始细胞标志物高表达的乳腺癌细胞系和三阴性乳腺癌患者样本中显著减少，三阴性乳腺癌是最具侵袭性的亚型。我们提出DACH1在乳腺癌中的表达缺失可能与表观遗传学改变有关。材料和方法：临床标本包括10例正常乳腺组织、26例腔型乳腺癌(ER+、PR+、HER1-2+)和32例三阴性乳腺癌(ER-、PR-、HER-)。从福尔马林固定的组织中提取基因组DNA，进行DACH1启动子的甲基化特异性聚合酶链式反应。免疫组织化学方法检测DACH1蛋白在人乳腺癌组织阵列中的表达。人三阴性乳腺癌细胞株MDA-MB-231和Sum159在添加10%胎牛血清和生长因子的DME培养液中培养。通过慢病毒转染法，在MDA-MB-231和Sum159细胞中建立了稳定表达DACH1的细胞系。用四甲基偶氮唑盐比色法和集落形成法检测细胞体外生长情况。在异种移植小鼠模型中检测体内肿瘤生长情况。结果：正常乳腺组织中未发现DACH1启动子区域的甲基化，26例腔型乳腺癌中有2例(7.7%)发生甲基化，32例三阴性乳腺癌中有10例(32%)发生甲基化。与文献报道一致，免疫组织化学染色显示DACH1在所有正常组织和大多数管腔型乳腺癌组织中均有核染色，而在三阴性乳腺癌组织中DACH1表达缺失或很弱。相应地，表达芯片显示DACH1基因在三阴性乳腺癌细胞系中的表达水平显著低于正常乳腺癌细胞系和管腔性乳腺癌细胞系。5-氮杂-2‘-脱氧氮杂胞苷处理MDA-MB-231和Sum159细胞可诱导DACH1的表达，并抑制细胞增殖。异位表达DACH1可抑制体外细胞生长和体内肿瘤形成。结论：在三阴性乳腺癌中，启动子高甲基化是导致DACH1失活的主要因素，通过表观遗传修饰使DACH1重新表达，可能为这种侵袭性乳腺癌提供新的治疗策略。引文格式：钱楚、那韩、严冬、寻源、郭明州、徐涵晓、于世英、吴孔明。三阴性乳腺癌中DACH1的表观遗传沉默参与了肿瘤的发生。[摘要]。见：美国癌症研究协会第106届年会论文集；2015年4月18日至22日，宾夕法尼亚州费城。费城(宾夕法尼亚州)：AACR；癌症资源2015；75(15补充)：摘要编号1074。电话：10.1158/1538-7445
BACKGROUND: Increasing evidence indicates that cell fate determination factor DACH1 functions as a tumor suppressor. Specifically, in estrogen receptor positive (luminal), highly expression of DACH1 predicted longer cancer specific survival and disease free interval, as well as reduced metastasis formation. Our analysis of over 2,000 patients demonstrated increased nuclear DACH1 expression correlated inversely with cellular mitosis and predicted 40 months survival advantage in breast cancer patients. But, endogenous DACH1 was dramatically reduced in breast cancer cell lines with high expression of tumor initiation cell markers and in patient samples of triple negative breast cancer, the most aggressive subtype. We proposed that epigenetically change might contribute to the loss expression of DACH1 in breast cancer. MATERIALS AND METHODS: Clinical samples included 10cases of normal breast tissues, 26 cases of luminal breast cancer(ER+,PR+,HER1-2+), and 32 cases of triple negative breast cancer(ER-,PR-,HER-). Genomic DNA was extracted from formalin-fixed tissue and methylation-specific PCR of DACH1 promoter was performed. DACH1 protein expression was detected in human breast cancer tissue arrays by immunohistochemistry. Human triple negative breast cancer cell lines MDA-MB-231 and sum159 were cultured in DME medium supplied with 10% fetal bovine serum and growth factors. Stable cell lines expressing DACH1 were established in MDA-MB-231 and Sum159 though lentivirus transfection. In vitro cell growth was evaluated by MTT assay and colony formation. In vivo tumor growth was measured in xenograft mice model. RESULTS: There is no methylation of DACH1 promoter region was found in normal breast tissues, but methylation was found in 2 out of 26 (7.7%) in luminal breast cancer and 10 of 32(32%) in triple negative breast cancer. Consisting with previous report, immunohistochemical stain revealed nuclear stain of DACH1 in all normal and majority of luminal type breast cancer tissues, but lost or very weak expression of DACH1 in triple negative cancer tissues. Correspondingly, expression microarrays demonstrated that DACH1 mRNA levels in triple negative breast cancer cell lines were dramatically less than that of normal breast cell line and luminal breast cancer cell lines. Treatment of MDA-MB-231 and Sum159 cells with 5-Aza-2′-deoxyazacytidine induced the expression of DACH1 and decreased cellular proliferation. Ectopic expression of DACH1 inhibited in vitro cell growth and in vivo tumor formation. CONCLUSION: Promoter hypermethylation is a main factor leading to the inactivation of DACH1 in triple negative breast cancer; Re-expression of DACH1by epigenetic modification might provide a novel therapeutic strategy for this aggressive cancer. Citation Format: Qian Chu, Na Han, Yan Dong, Xun Yuan, Mingzhou Guo, Hanxiao Xu, Shiying Yu, Kongming Wu. Epigenetic silencing of DACH1 in triple negative breast cancer contributes to the tumorigenesis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1074. doi:10.1158/1538-7445.AM2015-1074