表观遗传因子PHF20调控乳腺癌细胞重编程的分子机制与临床意义

In our previous study, we found that PHF20 is absolutely required for fully reprogramming into induced pluripotent stem cells. Importantly, PHF20 is overexpressed in breast cancer cells, and knock-down PHF20 in breast cancer reduced tumorigenicity dramatically. Therefore, we hypothesize that PHF20 plays a critical role in facilitating the epigenetic reprogramming of breast cancer; PHF20 could serve as a therapeutic target to eliminate breast cancer tumors. To test our hypothesis, we propose the following aims: 1) To investigate the role of PHF20 in breast cancer growth, metastasis, and cancer stem cell traits; 2) To dissect molecular mechanism of PHF20 regulating breast cancer epigenetic reprogramming by using RNA-seq, ChIP-seq, MeDIP-seq, and hMeDIP-seq; 3) To find out how PHF20 modulates target gene epigenetic status by binding to their regulatory regions, alone, or through interactions with other transcription and epigenetic factors; 4) To evaluate whether the elevated PHF20 expression is correlated with poor prognostic outcome of breast cancer patients; 5) To evaluate the efficacy of PHF20 targeted therapy in breast cancer preclinical animal model; 6) To generate a breast cancer reprogramming cellular model to screen epigenetic drugs. Our research will provide novel information regarding the function of epigenetic regulator-PHF20 in breast cancer stemness and reprogramming. Moreover, our study could generate an entirely new approach to screen epigenetic drugs. Therefore, the results of this research will benefit the hospitals and pharmaceutic companies of China by potentially identifying a novel way of treating breast cancer patients.

本项目前期实验结果表明表观遗传调控因子PHF20调控细胞重编程并在乳腺癌中显著上调，进一步研究发现在乳腺癌细胞中沉默PHF20基因显著抑制乳腺癌细胞的成瘤能力。因此，本项目拟用乳腺癌裸鼠模型证实敲除PHF20能抑制乳腺癌细胞的干性；用RNA-seq, ChIP-seq, MeDIP-seq和hMeDIP-seq进一步研究 PHF20基因对乳腺癌细胞重编程的表观遗传调控机理；用免疫共沉淀和ChIP-qPCR等方法阐明PHF20与DNA甲基化酶等表观遗传酶相互作用对于下游基因启动子的结合情况；在乳腺癌标本中明确 PHF20 基因与乳腺癌预后的关系，并在乳腺癌裸鼠模型上探索抑制PHF20对乳腺癌的治疗价值；最后建立乳腺癌细胞重编程细胞模型用于将来表观遗传药物的筛选。该研究对进一步揭示乳腺癌细胞重编程的表观遗传学调控机制，设计针对乳腺癌干细胞的新型治疗药物，提高我国乳腺癌的治疗水平具有重要意义。

乳腺癌是女性常见的恶性肿瘤之一。乳腺癌细胞具有很强的可塑性(plasticity)，在放化疗过程中，乳腺癌细胞可以从高分化状态重编程为低分化的干性状态从而导致治疗失败。本项目的前期工作发现PHF20调控细胞重编程和细胞多能性（2013 Cell）以及预实验发现PHF20在乳腺癌细胞中高表达，由此我们在本项目实施过程中系统研究了PHF20表达水平与乳腺癌等肿瘤临床表型的关联，重点研究PHF20调控乳腺癌等肿瘤细胞可塑性和重编程的表观遗传分子机制，以及初步筛选出抑制PHF20和乳腺癌重编程的化合物。在本项目实施过程中取得的重要成果包括：(i) 揭示调控乳腺癌可塑性的表观遗传特征，并且阐明PHF20在乳腺癌等肿瘤中调控肿瘤可塑性的表观遗传分子机制。部分数据以主持人为共同第一作者发表在 J Mol Cell Biol杂志，其余数据正在整理准备投稿；(ii) 阐明PHF20多个下游因子调控乳腺癌等肿瘤可塑性和干性的表观遗传机制。这部分数据以主持人为最后通讯作者发表在Cancer Res和Mol Cancer Res等杂志; (iii)筛选出2个抑制乳腺癌干细胞特性的表观遗传化合物药物，以主持人为共同通讯作者发表在Biomed Pharmacother杂志。在本项目资助下，主持人发表标注SCI科研论文共计12篇, 其中影响因子大于10的论文2篇，通讯（含共同）作者论文8篇，本项目为第一标注的论文4篇，另外还发表SCI综述论文6篇。在成果转化方面，主持人共计申请发明专利5项。在人才培养方面，项目实施期间主持人培养博士研究生2名，硕士研究生3名。本项目从肿瘤细胞可塑性和重编程的全新角度探究肿瘤干性的产生机制，产生的成果为寻找新的乳腺癌治疗靶点和新的乳腺癌治疗策略探明了道路。