Targeted epigenetic therapy of triple-negative breast cancer

描述(申请人提供)：产生异常转录的多个表观遗传学程序有助于乳腺癌的发展。三重阴性乳腺癌在年轻和非裔美国女性中很常见，它有一组基本基因被DNA超甲基化沉默，导致预后较差的基本表型。我们相信，一旦确定了导致乳腺癌发生的特定表观遗传学靶点，将导致一种治疗这种疾病的新方法。为此，我们使用SID诱骗来破坏SIN3共抑制物的PAH2结构域，该结构域与一小群包含称为SID(mSin3A相互作用域)的特定基序的转录因子结合。SIN3作为多亚单位辅阻遏物支架蛋白，通过招募HDAC、BP2/JARID1A来调节转录，HDAC、BP2/JARID1A是组蛋白H3的二甲基化和三甲基化赖氨酸4的去甲基酶，对从头DNA甲基化和其他染色质修饰物至关重要。SIN3的PAH2结构域与有限数量的SID转录因子包括REST、MAD1、KLF-9、-10、-11、-13和-16、UME6和HBP结合的破坏预示着比HDAC抑制剂或去甲基化药物处理更具选择性的表观遗传效应。我们的结果表明，在体内外的三阴性人和小鼠乳腺癌模型中，最小的SID或编码的13个氨基酸的多肽(SID肽)处理破坏了SID转录因子与Sin3A PAH2结构域的结合，导致了形态发生、侵袭丧失和接触抑制的深刻表型变化。这种从基础表型到更分化的管腔表型的转变涉及表观遗传重新编程，有助于Ecadherin、雌激素和维甲酸受体(ER和RARs)的重新表达，从而支持上皮/间充质转化(EMT)逆转的假说。在3个三联阴性的乳腺癌细胞系中观察到这一现象，而在2个ER阳性的乳腺癌细胞系中未观察到这种情况。此外，在人类三阴性细胞系中，对雌激素、他莫昔芬和RAR激动剂的反应性得到恢复。从MMTV-myc转基因模型中产生的肿瘤细胞中获得的肿瘤细胞经SID诱骗后原位接种于FVB小鼠体内，肿瘤生长受到抑制(70%)。我们正在进行的研究是开发稳定的SID多肽和小分子抑制剂，并在大量乳腺癌细胞株中进行体外评估，以建立临床前设计的三重阴性特异性和参数。剖析SID诱骗干扰PAH2-Sin 3和SID转录的机制和后果将被深入研究，并将为理解基础表型的表观遗传调控和深入了解癌症发生中的EMT假说提供新的见解。这为三阴性乳腺癌提供了其他治疗选择，也提供了新的可用药靶点。 公共卫生相关性：我们已经使用诱饵(SID)来干扰特定的表观遗传靶点，该靶点可以诱导人乳腺癌细胞、形态发生、体内侵袭、分化和生长抑制的丧失，并恢复对抗雌激素的敏感性。对SID诱饵干扰的机制和后果的剖析将被深入研究，并将为理解基础表型的表观遗传调节和对乳腺癌的发展提供新的见解。SID诱饵的成功开发为三阴性乳腺癌提供了其他治疗选择，也提供了新的可用药靶点。

DESCRIPTION (provided by applicant): Multiple epigenetic programs creating aberrant transcription contribute to the development of breast cancer. Triple negative breast cancer, common in young and African American women has a group of essential genes silenced by DNA hypermethylation that contribute to the poorer prognosis basal phenotype. We believe that specific epigenetic targets that contribute to the development of breast cancer, once identified, will lead to a novel approach to the treatment of this disease. To this end we targeted the disruption of the PAH2 domain of the Sin3 co-repressor that binds to a small group of transcription factors that contain a specific motif called SID (mSin3A interaction domain) using SID decoys. Sin3 serves as a multisubunit corepressor scaffold protein that regulates transcription by recruiting HDAC, BP2/JARID1A, a demethylase specific for di- and trimethylated lysine 4 of histone H3, critical for de novo DNA methylations and other chromatin modifiers. The disruption of PAH2 domain of Sin3 binding to a limited number of SID transcription factors including REST, MAD1, KLF-9, -10, -11, -13 and -16, UME6 and HBP predicts a more selective epigenetic effect than treatment with HDAC inhibitors or demethylating agents. Our data demonstrate that transfection of the minimal SID or treatment with the encoded 13 amino acid peptide (SID peptide) disrupts SID transcription factor binding to the Sin3A PAH2 domain induces profound phenotypic changes of morphogenesis, loss of invasion, contact inhibition in triple negative human and mouse breast cancer models in vitro and in vivo. This switch from a basal to a more differentiated luminal phenotype involves epigenetic reprogramming contributing to re-expression of Ecadherin, estrogen and retinoic acid receptors (ER and RARs) adds support to the hypothesis of reversion of the Epithelial/Mesenchymal Transition (EMT). This was observed in 3 triple negative but not in 2 ER positive breast cancer cell lines. Moreover, in the human triple- negative cell lines the responsiveness to estrogen, tamoxifen and RAR agonists is restored. Tumor growth is inhibited (70%) when tumor cells obtained from the tumors generated in the MMTV-myc transgenic models were transfected with the SID decoy and inoculated orthotopically in FVB mice. Our ongoing research is to develop stable SID peptide and small molecule inhibitors and evaluate in vitro in a large number of breast cancer cell lines to establish triple negative specificity and parameters for pre-clinical design. Dissecting the mechanisms and consequences of SID decoy disruption of PAH2-Sin 3 and SID transcription will be studied in depth and should offer new insights in understanding epigenetic regulation of the basal phenotype and insight into the EMT hypothesis in cancer development. This offers other therapeutic options for triple negative breast cancer and also novel druggable targets. PUBLIC HEALTH RELEVANCE: We have used a decoy (SID) to disrupt a specific epigenetic target which induces human triple negative breast cancer cell, morphogenesis, loss of invasion, differentiation, growth inhibition in vivo and restores sensitivity to anti-estrogen. Dissecting the mechanisms and consequences of SID decoy disruption will be studied in depth and should offer new insights in understanding epigenetic regulation of the basal phenotype and insight into breast cancer development. Successful SID decoy development offers other therapeutic options for triple negative breast cancer and also novel drugable targets.