We investigated the effect of stem cell marker dopamine receptor D2 (DRD2) on the proliferation of hormone-receptor-negative breast cancer cells. High-throughput DNA methylation sequencing on an 850 K chip was used to pre-screen breast cancer tissues with significant methylation differences. The expression of DRD2 in breast cancer and normal breast tissues, and clinical risk factors, were detected by pyrophosphoric acid validation and immunohistochemistry. In vitro and in vivo experiments verified the possible molecular signaling pathways. DRD2 promoter region was hypomethylated in hormone-receptor-negative breast cancer or with high-risk factors compared to the normal tissues. The proliferation of breast cancer cells was enhanced after DRD2 was upregulated and decreased after DRD2 was downregulated. In vivo experiments found that tumor growth and the expression of antigen KI-67 (Ki67) and the cluster of differentiation 31 (CD31) were improved by the overexpression of DRD2 and inhibited by the down expression of DRD2. In vivo and in vitro experiments demonstrated the phosphorylation of filamin A and extracellular signal-regulated kinase (FLNA-ERK) was influenced by the expression of DRD2, suggesting DRD2 plays a role in the FLNA-ERK signaling pathway. Methylation inhibitors (5-aza-2-deoxycytidine, 5-azadc) partially reversed the inhibitory effect of DRD2 down expression on cell proliferation, migration, and tumor growth in animal models, indicating that inhibition of DRD2 methylation promotes cancer development. This study demonstrated the DRD2 promoter region is hypomethylated in hormone-receptor-negative breast cancer or with high-risk factors. The methylation status of the DRD2 promoter and FLNA-ERK signaling pathway and the DRD2 expression in breast cancer treatment need to be considered.

我们研究了干细胞标记物多巴胺受体 D2 (DRD2) 对激素受体阴性乳腺癌细胞增殖的影响。采用850 K芯片上的高通量DNA甲基化测序来预筛选具有显着甲基化差异的乳腺癌组织。通过焦磷酸验证和免疫组化检测DRD2在乳腺癌和正常乳腺组织中的表达以及临床危险因素。体外和体内实验验证了可能的分子信号通路。与正常组织相比，激素受体阴性乳腺癌或具有高危因素的乳腺癌中 DRD2 启动子区域甲基化程度较低。DRD2上调后乳腺癌细胞增殖能力增强，DRD2下调后乳腺癌细胞增殖能力降低。体内实验发现，DRD2的过表达可以促进肿瘤的生长以及抗原KI-67（Ki67）和分化簇31（CD31）的表达，而DRD2的下调则可以抑制肿瘤的生长和抗原KI-67（Ki67）和分化簇31（CD31）的表达。体内和体外实验表明，Filamin A 和细胞外信号调节激酶 (FLNA-ERK) 的磷酸化受到 DRD2 表达的影响，表明 DRD2 在 FLNA-ERK 信号通路中发挥作用。甲基化抑制剂（5-aza-2-脱氧胞苷，5-azadc）部分逆转了动物模型中DRD2下调表达对细胞增殖、迁移和肿瘤生长的抑制作用，表明抑制DRD2甲基化可促进癌症发展。这项研究表明，在激素受体阴性或具有高危因素的乳腺癌中，DRD2 启动子区域甲基化程度较低。乳腺癌治疗中需要考虑DRD2启动子和FLNA-ERK信号通路的甲基化状态以及DRD2的表达。