Department of Breast Surgery, Second Hospital of Dalian Medical University, Dalian 116023, China.
Surg Oncol. 2013 Dec;22(4):217-23. doi: 10.1016/j.suronc.2013.07.001. Epub 2013 Aug 27.
To investigate the expression status of PIWIL2 and piR-932 in breast cancer stem cells and the role they could play in tumor cell growth and metastasis through Latexin.
CD44(+)/CD24(-) tumor cells (CSC) from clinical specimens were sorted using flow cytometry. PIWIL2 expression status was detected in CSC cells by microarray analysis and 1086 breast cancer specimens by Western blot and immunohistochemistry staining. piR-932 expression was also detected in CSC cells by piRNA microarray assay. The relationship between the PIWIL2 protein and clinico-pathological parameters and prognosis was subsequently determined.
CSC cells are more likely to generate new tumors in mice and cell microspheres that are deficient in NOD/SCID compared to the control group. PIWIL2 protein was expressed higher in CSC cells compared to the control cells. In total, 334 (30.76%) of the 1086 breast cases showed high PIWIL2 expression. PIWIL2 was observed to be related to age, tumor size, histological type, tumor stage, and lymph node metastasis (all P < 0.05). Furthermore, we have found that one of the Piwi-interacting RNAs (piRNAs) called piR-932 expressed significantly higher in the breast cancer cells that were induced to EMT, and it could form immune complexes through immunoprecipitation with PIWIL2; in PIWIL2+ breast cancer stem cells, Latexin expression significantly reduced because of its promoter region CpG island methylation.
These results suggest that the combination of piR-932 and PIWIL2 may be a positive regulator in the process of breast cancer stem cells through promoting the methylation of Latexin, and they both could be the potential targets for blocking the metastasis of breast cancer.
通过 Latexin 研究 PIWIL2 和 piR-932 在乳腺癌干细胞中的表达状态及其在肿瘤细胞生长和转移中所起的作用。
使用流式细胞术从临床标本中分离 CD44(+)/CD24(-)肿瘤细胞（CSC）。通过微阵列分析和 Western blot 及免疫组织化学染色检测 CSC 细胞中 PIWIL2 的表达状态。通过 piRNA 微阵列检测 CSC 细胞中 piR-932 的表达。随后确定 PIWIL2 蛋白与临床病理参数和预后的关系。
与对照组相比，CSC 细胞在小鼠和 NOD/SCID 细胞微球中更易产生新肿瘤。CSC 细胞中 PIWIL2 蛋白表达高于对照细胞。在总共 1086 例乳腺癌病例中，有 334 例（30.76%）表现出高 PIWIL2 表达。PIWIL2 与年龄、肿瘤大小、组织学类型、肿瘤分期和淋巴结转移有关（均 P<0.05）。此外，我们发现一种称为 piR-932 的 Piwi 相互作用 RNA（piRNA）在诱导 EMT 的乳腺癌细胞中表达显著升高，并且可以通过与 PIWIL2 的免疫沉淀形成免疫复合物；在 PIWIL2+乳腺癌干细胞中，由于其启动子区 CpG 岛甲基化，Latexin 的表达显著降低。
这些结果表明，piR-932 和 PIWIL2 的组合可能通过促进 Latexin 的甲基化成为乳腺癌干细胞过程中的正调节剂，它们都可能成为阻断乳腺癌转移的潜在靶点。
