Department of Clinical Pharmacology & Therapeutics, Nizam's Institute of Medical Sciences, Panjagutta, Hyderabad, Andhra Pradesh, India.
Mol Cell Biochem. 2012 Feb;361(1-2):189-95. doi: 10.1007/s11010-011-1103-z. Epub 2011 Oct 11.
In view of recent studies highlighting the prognostic relevance of expression and CpG island methylator phenotype (CIMP) of Bcl-2/adenovirus E1B 19 kDa-interacting protein 3 (BNIP3) in invasive duct cell carcinoma (IDC), we hypothesized in this article that impaired one-carbon metabolism might influence CIMP phenotype of BNIP3. In order to substantiate the prognostic relevance of BNIP3, we explored its association with 8-oxo-2'deoxyguanosine (8-oxodG), a marker of oxidative stress with prognostic relevance. BNIP3 expression and CIMP phenotype were studied using semi-quantitative RT-PCR and combined bisulfite restriction analysis (COBRA), respectively, in 56 IDC tumors. Eight polymorphisms in one-carbon metabolism were studied using PCR-RFLP and PCR-AFLP approaches. 8-oxodG was measured using competitive ELISA kit. BNIP3 was found to be upregulated in IDC (cases vs. controls: 0.94 ± 0.05 vs. 0.18 ± 0.08, P < 0.0001). COBRA analysis confirmed hypomethylation of BNIP3 promoter CpG island in these cases. CIMP phenotype of BNIP3 showed positive association with tubule formation (P = 0.034) and methionine synthase reductase (MTRR) A66G (P = 0.002); inverse association with cytosolic serine hydroxyl methyltransferase (cSHMT) C1420T (P < 0.005) and 8-oxodG (<10% vs. >10% methylation: 7.24 ± 2.77 ng/ml vs. 4.42 ± 2.93 ng/ml, P < 0.0005); and no association with nuclear pleomorphism or mitotic index or ER, PR, and HER statuses. Synergistic effect of MTR A2756G and MTRR A66G variants on BNIP3 hypermethylator phenotype was clearly evident (P < 0.0007). MTRR A66G and cSHMT C1420T polymorphisms influence CIMP phenotype of BNIP3, thus epigenetically regulating BNIP3 in breast cancer. The linear association between BNIP3 and 8-oxodG substantiates the role of BNIP3 as redox sensor as well as prognostic marker in breast cancer.
鉴于最近的研究强调了 Bcl-2/腺病毒 E1B 19 kDa 相互作用蛋白 3（BNIP3）的表达和 CpG 岛甲基化表型（CIMP）在浸润性导管细胞癌（IDC）中的预后相关性，我们假设在本文中，一碳代谢的损伤可能会影响 BNIP3 的 CIMP 表型。为了证实 BNIP3 的预后相关性，我们探讨了它与 8-氧-2'-脱氧鸟苷（8-oxodG）的关联，8-oxodG 是一种具有预后相关性的氧化应激标志物。使用半定量 RT-PCR 和联合亚硫酸氢盐限制分析（COBRA）分别研究了 56 例 IDC 肿瘤中的 BNIP3 表达和 CIMP 表型。使用 PCR-RFLP 和 PCR-AFLP 方法研究了一个碳代谢中的 8 个多态性。使用竞争性 ELISA 试剂盒测量 8-oxodG。发现 BNIP3 在 IDC 中上调（病例与对照组：0.94 ± 0.05 与 0.18 ± 0.08，P <0.0001）。COBRA 分析证实这些病例中 BNIP3 启动子 CpG 岛的低甲基化。BNIP3 的 CIMP 表型与小管形成呈正相关（P = 0.034），与甲硫氨酸合成酶还原酶（MTRR）A66G 呈正相关（P = 0.002）；与细胞质丝氨酸羟甲基转移酶（cSHMT）C1420T 呈负相关（P <0.005）和 8-oxodG（<10% 与>10% 甲基化：7.24 ± 2.77 ng/ml 与 4.42 ± 2.93 ng/ml，P <0.0005）；与核多形性或有丝分裂指数或 ER、PR 和 HER 状态无关。MTR A2756G 和 MTRR A66G 变体对 BNIP3 高甲基化表型的协同作用非常明显（P <0.0007）。MTRR A66G 和 cSHMT C1420T 多态性影响 BNIP3 的 CIMP 表型，从而在乳腺癌中通过表观遗传调控 BNIP3。BNIP3 与 8-oxodG 之间的线性关联证实了 BNIP3 作为氧化还原传感器以及乳腺癌预后标志物的作用。
