DNA5-羟甲基胞嘧啶(5hmC)是通过动态5mC氧化过程产生的,有助于组织规范,据报道,在包括泌尿生殖系统癌症在内的多种癌症中,5hmC的丢失。然而,5hmC也是细胞类型特异性的,分化的肿瘤细胞和肿瘤干细胞之间可能存在差异。因此,5hmC的癌症相关变化可能是由肿瘤组织内不同组的肿瘤细胞造成的。
这里,我们应用了一种敏感的基于免疫沉淀的方法(hMeDIP-seq)来分析泌尿生殖系统癌变过程中的5hmC变化(包括前列腺,尿路上皮和肾脏)。我们证实了5hmC在泌尿生殖系统组织中的组织特异性分布,并确定了5hmC在泌尿生殖系统癌症中共存的区域增益和全球损失。在肿瘤发生过程中获得5hmC的基因在调节干性和缺氧方面功能丰富,而与不良临床预后相关,而与肿瘤类型的差异无关。我们发现,在两个前列腺癌细胞系中,在软纤维蛋白凝胶诱导的3D肿瘤球体中发生了5hmC的增加,具有肿瘤再增殖表型。22RV1和PC3,与传统的二维(2D)刚性餐具相比。然后,我们定义了一个恶性特征,来自差异羟甲基化区域影响的癌症干细胞样细胞的基因,这可以预测更差的临床结果,并从前列腺癌肿瘤中鉴定出表型恶性细胞群。值得注意的是,抗氧化的维生素C衍生物,抗坏血酸磷酸镁,恢复5hmC并杀死癌症干细胞样细胞,导致前列腺癌细胞系凋亡。
集体,我们的研究剖析了5hmC在维持肿瘤干细胞样细胞中的区域增益,以及与不良预后相关的区域增益,通过5hmC重编程,为维生素C的表观遗传分化治疗提供了概念证明。
DNA 5-hydroxymethylcytosine (5hmC) is produced by dynamic 5mC oxidation process contributing to tissue specification, and loss of 5hmC has been reported in multiple cancers including genitourinary cancers. However, 5hmC is also cell-type specific, and its variability may exist between differentiated tumor cells and cancer stem cells. Thus, cancer-associated changes in 5hmC may be contributed by distinct sets of tumor cells within the tumor tissues.
Here, we applied a sensitive immunoprecipitation-based method (hMeDIP-seq) to analyze 5hmC changes during genitourinary carcinogenesis (including prostate, urothelial and kidney). We confirmed the tissue-specific distribution of 5hmC in genitourinary tissues and identified regional gain and global loss of 5hmC coexisting in genitourinary cancers. The genes with gain of 5hmC during tumorigenesis were functionally enriched in regulating stemness and hypoxia, whereas were associated with poor clinical prognosis irrespective of their differences in tumor type. We identified that gain of 5hmC occurred in soft fibrin gel-induced 3D tumor spheres with a tumor-repopulating phenotype in two prostate cancer cell lines, 22RV1 and PC3, compared with conventional two-dimensional (2D) rigid dishes. Then, we defined a malignant signature derived from the differentially hydroxymethylated regions affected genes of cancer stem-like cells, which could predict a worse clinical outcome and identified phenotypically malignant populations of cells from prostate cancer tumors. Notably, an oxidation-resistant vitamin C derivative, ascorbyl phosphate magnesium, restored 5hmC and killed the cancer stem cell-like cells leading to apoptosis in prostate cancer cell lines.
Collectively, our study dissects the regional gain of 5hmC in maintaining cancer stem-like cells and related to poor prognosis, which provides proof of concept for an epigenetic differentiation therapy with vitamin C by 5hmC reprogramming.