Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
J Exp Clin Cancer Res. 2012 Feb 8;31(1):12. doi: 10.1186/1756-9966-31-12.
Human interacting protein X1 (PinX1) has been identified as a critical telomerase inhibitor and proposed to be a putative tumor suppressor gene. Loss of PinX1 has been found in a large variety of malignancies, however, its function in inhibiting telomerase activity of tumor cells is not well documented. Here we show that PinX1 is essential for down-regulation telomerase activity of nasopharyngeal carcinoma.
Expression vectors of human PinX1 (pEGFP-C3-PinX1) and its small interfering RNA (PinX1-FAM-siRNA) were constructed and transfected into NPC. Their effects on mRNA of telomerase catalytic subunit (hTERT), telomerase activity, cell proliferation, cell migration, wound healing, cell cycles and apoptosis were examined using semi-quantitative RT-PCR, stretch PCR, MTT assay, Transwell, scratch assay and flow cytometry, respectively.
Transfection of pEGFP-C3-PinX1 and PinX1-FAM-siRNA increased and reduced PinX1 mRNA by 1.6-fold and 70%, respectively. Over-expression of PinX1 decreased hTERT mRNA by 21%, reduced telomerase activity, inhibited cell growth, migration and wound healing ability, arrested cells in G0/G1 phase, and increased apoptotic index. In contrast, down-regulation of PinX1 did not alter the above characteristics.
PinX1 may play important roles in NPC proliferation, migration and apoptosis and has application potential in tumor-targeted gene therapy.
人类相互作用蛋白 X1（PinX1）已被鉴定为一种关键的端粒酶抑制剂，并被提议为一种潜在的肿瘤抑制基因。在各种恶性肿瘤中都发现了 PinX1 的缺失，然而，其抑制肿瘤细胞端粒酶活性的功能尚未得到很好的证明。在这里，我们表明 PinX1 对于下调鼻咽癌的端粒酶活性是必需的。
构建了人 PinX1（pEGFP-C3-PinX1）的表达载体及其小干扰 RNA（PinX1-FAM-siRNA），并转染到 NPC 中。使用半定量 RT-PCR、拉伸 PCR、MTT 测定、Transwell、划痕测定和流式细胞术分别检测它们对端粒酶催化亚基（hTERT）mRNA、端粒酶活性、细胞增殖、细胞迁移、伤口愈合、细胞周期和细胞凋亡的影响。
转染 pEGFP-C3-PinX1 和 PinX1-FAM-siRNA 分别使 PinX1 mRNA 增加了 1.6 倍和减少了 70%。PinX1 的过表达使 hTERT mRNA 减少了 21%，降低了端粒酶活性，抑制了细胞生长、迁移和伤口愈合能力，使细胞停滞在 G0/G1 期，并增加了凋亡指数。相比之下，下调 PinX1 并没有改变上述特征。
PinX1 可能在 NPC 的增殖、迁移和凋亡中发挥重要作用，在肿瘤靶向基因治疗中有应用潜力。
