College of Pharmacy, the Ohio State University, Columbus, Ohio, United States of America.
PLoS One. 2013 Oct 2;8(10):e76402. doi: 10.1371/journal.pone.0076402. eCollection 2013.
Identifying targets of dysregulated microRNAs (miRNAs) will enhance our understanding of how altered miRNA expression contributes to the malignant phenotype of breast cancer. The expression of miR-205 was reduced in four breast cancer cell lines compared to the normal-like epithelial cell line MCF10A and in tumor and metastatic tissues compared to adjacent benign breast tissue. Two predicted binding sites for miR-205 were identified in the 3' untranslated region of the high mobility group box 3 gene, HMGB3. Both dual-luciferase reporter assay and Western blotting confirmed that miR-205 binds to and regulates HMGB3. To further explore miR-205 targeting of HMGB3, WST-1 proliferation and in vitro invasion assays were performed in MDA-MB-231 and BT549 cells transiently transfected with precursor miR-205 oligonucleotide or HMGB3 small interfering RNA (siRNA). Both treatments reduced the proliferation and invasion of the cancer cells. The mRNA and protein levels of HMGB3 were higher in the tumor compared to adjacent benign specimens and there was an indirect correlation between the expression of HMGB3 mRNA and patient survival. Treatment of breast cancer cells with 5-Aza/TSA derepressed miR-205 and reduced HMGB3 mRNA while knockdown of the transcriptional repressor NRSF/REST, reduced miR-205 and increased HMGB3. In conclusion, regulation of HMGB3 by miR-205 reduced both proliferation and invasion of breast cancer cells. Our findings suggest that modulating miR-205 and/or targeting HMGB3 are potential therapies for advanced breast cancer.
鉴定失调 microRNA（miRNA）的靶标将增强我们对 miRNA 表达改变如何导致乳腺癌恶性表型的理解。与正常上皮细胞系 MCF10A 相比，四种乳腺癌细胞系中 miR-205 的表达降低，与肿瘤和转移性组织相比，相邻良性乳腺组织中的 miR-205 表达降低。在高迁移率族框 3 基因（HMGB3）的 3'非翻译区中鉴定出两个 miR-205 的预测结合位点。双荧光素酶报告基因检测和 Western blot 均证实 miR-205 结合并调节 HMGB3。为了进一步探讨 miR-205 对 HMGB3 的靶向作用，在瞬时转染前体 miR-205 寡核苷酸或 HMGB3 小干扰 RNA（siRNA）的 MDA-MB-231 和 BT549 细胞中进行了 WST-1 增殖和体外侵袭实验。两种处理均降低了癌细胞的增殖和侵袭。与相邻良性标本相比，肿瘤中 HMGB3 的 mRNA 和蛋白水平更高，HMGB3 mRNA 的表达与患者生存之间存在间接相关性。用 5-Aza/TSA 处理乳腺癌细胞可使 miR-205 去抑制并降低 HMGB3 mRNA，而敲低转录抑制因子 NRSF/REST 可降低 miR-205 并增加 HMGB3。总之，miR-205 对 HMGB3 的调节降低了乳腺癌细胞的增殖和侵袭。我们的研究结果表明，调节 miR-205 和/或靶向 HMGB3 可能是治疗晚期乳腺癌的潜在疗法。
