Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Medical Foundation Building (K25), The University of Sydney, Sydney, New South Wales 2006, Australia.
Molecular Pharmacology and Pathology Program, Discipline of Pathology and Bosch Institute, Medical Foundation Building (K25), The University of Sydney, Sydney, New South Wales 2006, Australia.
Biochim Biophys Acta Mol Basis Dis. 2018 Aug;1864(8):2644-2663. doi: 10.1016/j.bbadis.2018.04.011. Epub 2018 Apr 19.
The metastasis suppressor, N-myc downstream regulated gene-1 (NDRG1), exhibits pleiotropic activity, inhibiting metastasis of various tumor-types, while being correlated with metastasis in others. Notably, NDRG1 phosphorylation and cleavage are associated with its function, although it is unclear if these modifications occur universally, or selectively, in different cancer cell-types and if it contributes to its pleiotropy. Considering the suggested DNA repair role of nuclear NDRG1, the effects of the above post-translational modifications on its nuclear localization was examined. Herein, the full-length (FL) and truncated (T) NDRG1 isoforms were detected using a C-terminus-directed antibody, while only the FL isoform was identified using an N-terminus-directed antibody. For the first time, we demonstrate that the expression of the NDRG1 FL and T forms occurs in all cancer cell-types examined, as does its phosphorylation (p-NDRG1) at Ser330 and Thr346. The FL isoform localized highly in the nucleus compared to the T isoform. Moreover, p-NDRG1 (Ser330) was also markedly localized in the nucleus, while p-NDRG1 (Thr346) was predominantly cytoplasmic in all cell-types. These results indicate the N-terminus region and phosphorylation at Ser330 could be crucial for NDRG1 nuclear localization and function. PTEN silencing indicated that p-NDRG1 (Thr346) could be regulated differentially in different tumor cell-types, indicating PTEN may be involved in the mechanism(s) underlying the pleiotropic activity of NDRG1. Finally, therapeutics of the di-2-pyridylketone thiosemicarbazone class increased nuclear NDRG1 isoforms (FL and T) detected by the C-terminus-directed antibody in HepG2 cells, while having no significant effect in PC3 cells, indicating differential activity depending on the cell-type.
抑瘤基因 N-myc 下游调节基因 1（NDRG1）是一种多功能蛋白，可抑制多种肿瘤类型的转移，而在其他肿瘤中与转移相关。值得注意的是，NDRG1 的磷酸化和切割与其功能相关，尽管尚不清楚这些修饰是否普遍存在于不同的癌细胞类型中，以及它们是否有助于其多功能性。考虑到核 NDRG1 的潜在 DNA 修复作用，研究了上述翻译后修饰对其核定位的影响。在此，使用 C 端导向抗体检测全长（FL）和截断（T）NDRG1 同工型，而仅使用 N 端导向抗体鉴定 FL 同工型。首次证明，在所有研究的癌细胞类型中均表达 NDRG1 FL 和 T 形式，并且其丝氨酸 330 位和苏氨酸 346 位磷酸化（p-NDRG1）也是如此。与 T 同工型相比，FL 同工型高度定位于核内。此外，p-NDRG1（Ser330）也明显定位于核内，而 p-NDRG1（Thr346）在所有细胞类型中主要位于细胞质中。这些结果表明，N 端区域和丝氨酸 330 位的磷酸化对于 NDRG1 的核定位和功能至关重要。PTEN 沉默表明，不同肿瘤细胞类型中 p-NDRG1（Thr346）的调节可能不同，表明 PTEN 可能参与了 NDRG1 多效性活性的机制。最后，二吡啶酮硫代缩氨基脲类治疗剂增加了 HepG2 细胞中 C 端导向抗体检测到的核 NDRG1 同工型（FL 和 T），而对 PC3 细胞无明显影响，表明根据细胞类型存在不同的活性。
