Department of Oncology, The Second Hospital of Dalian Medical University, No.467 Zhongshan Road, Shahekou District, Dalian City, Liaoning Province, China.
Funct Integr Genomics. 2024 Sep 12;24(5):159. doi: 10.1007/s10142-024-01442-8.
Breast cancer is the second primary cause of cancer death among women. Long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) is a central regulator for X chromosome inactivation, and its abnormal expression is a primary feature of breast cancer. So far, the mechanism of XIST in breast cancer has not been fully elucidated. We attempted to illustrate the mechanism of XIST in breast cancer. The expressions of XIST, microRNA-455-3p (miR-455-3p) in breast cancer were measured using quantitative real-time PCR. The expressions of homeobox C4 (HOXC4) were assessed with immunohistochemical and Western blot. Also, the functions of XIST in breast cancer were assessed by Cell Counting Kit-8 analysis, colony formation assay, flow cytometry, Western blot, Transwell, and cell scratch assays. Meanwhile, the mechanism of XIST in breast cancer was validated using database analysis and dual-luciferase reporter assay. Furthermore, the function of XIST in breast cancer in vivo was estimated by tumor xenograft model, immunohistochemical assay, and hematoxylin-eosin staining. XIST and HOXC4 expressions were increased, but miR-455-3p expressions were decreased in breast cancer tissues and cells. Knocking down XIST restrained breast cancer cell proliferation, invasion, migration, epithelial-mesenchymal transformation (EMT), and induced cell cycle arrest at G0/G1. Meanwhile, XIST interacted with miR-455-3p, while miR-455-3p interacted with HOXC4. XIST knockdown repressed breast cancer cell proliferation, invasion, and EMT, while miR-455-3p inhibitor or HOXC4 overexpression abolished those impacts. HOXC4 overexpression also blocked the impacts of miR-455-3p mimic on breast cancer cell malignant behavior. In vivo experimental data further indicated that XIST knockdown repressed breast cancer cell tumorigenic ability, and decreased HOXC4 and p-SMAD3 (TGF-β/SMAD-related protein) expressions.XIST/miR-455-3p/HOXC4 facilitated breast cancer development by activating the TGF-β/SMAD pathway.
乳腺癌是女性癌症死亡的第二大主要原因。长非编码 RNA（lncRNA）X 失活特异性转录物（XIST）是 X 染色体失活的主要调节剂，其异常表达是乳腺癌的主要特征。迄今为止，XIST 在乳腺癌中的作用机制尚未完全阐明。我们试图阐述 XIST 在乳腺癌中的作用机制。使用实时定量 PCR 测量乳腺癌中 XIST 和 microRNA-455-3p（miR-455-3p）的表达。使用免疫组织化学和 Western blot 评估同源盒 C4（HOXC4）的表达。还通过细胞计数试剂盒-8 分析、集落形成测定、流式细胞术、Western blot、Transwell 和细胞划痕测定评估 XIST 在乳腺癌中的功能。同时，通过数据库分析和双荧光素酶报告基因测定验证 XIST 在乳腺癌中的作用机制。此外，通过肿瘤异种移植模型、免疫组织化学检测和苏木精-伊红染色评估 XIST 在体内乳腺癌中的功能。XIST 和 HOXC4 的表达在乳腺癌组织和细胞中增加，而 miR-455-3p 的表达减少。敲低 XIST 抑制乳腺癌细胞增殖、侵袭、迁移、上皮-间充质转化（EMT），并诱导细胞周期停滞在 G0/G1。同时，XIST 与 miR-455-3p 相互作用，而 miR-455-3p 与 HOXC4 相互作用。XIST 敲低抑制乳腺癌细胞增殖、侵袭和 EMT，而 miR-455-3p 抑制剂或 HOXC4 过表达消除了这些影响。HOXC4 过表达也阻断了 miR-455-3p 模拟物对乳腺癌细胞恶性行为的影响。体内实验数据进一步表明，XIST 敲低抑制乳腺癌细胞的致瘤能力，并降低 HOXC4 和 p-SMAD3（TGF-β/SMAD 相关蛋白）的表达。XIST/miR-455-3p/HOXC4 通过激活 TGF-β/SMAD 通路促进乳腺癌的发展。
