High expression of NDRG3 associates with positive lymph node metastasis and unfavourable overall survival in laryngeal squamous cell carcinoma
PATHOLOGY
Authors: Ma, Jun; Liu, Shaofeng; Zhang, Wei; Zhang, Fan; Wang, Sufen; Wu, Lifeng; Yan, Renchun; Wu, Lijuan; Wang, Chuanxi; Zha, Zhihong; Sun, Jingwu
Abstract
N-myc downstream-regulated gene 3 (NDRG3), which belongs to the NDRG family, is believed to play important roles in human cancer. In this present study, one-step quantitative reverse transcription-polymerase chain reaction (qPCR) and western blotting tests with 10 fresh-frozen laryngeal squamous cell carcinoma (LSCC) samples and immunohistochemistry (IHC) analysis in 109 LSCC cases were performed to investigate the relationship between NDRG3 expression and the clinicopathological characteristics of LSCC. Results demonstrated that NDRG3 mRNA and protein expression levels were statistically higher in LSCC tissues than that in non-cancerous tissues (all p < 0.05). IHC data showed that the NDRG3 protein expression was remarkably correlated with lymph node metastasis (p = 0.043). Univariate and multivariate survival analysis implied that high NDRG3 expression (p = 0.004), lymph node metastasis (p = 0.044) and TNM stage (p = 0.020) were independently associated with the unfavourable overall survival of patients with LSCC. The above findings suggested that NDRG3 may be identified as a novel biomarker predicting the prognosis of LSCC.
Structural and Biophysical Analyses of Human N-Myc Downstream-Regulated Gene 3 (NDRG3) Protein
BIOMOLECULES
Authors: Kim, Kyung Rok; Kim, Kyung A.; Park, Joon Sung; Jang, Jun Young; Choi, Yuri; Lee, Hyung Ho; Lee, Dong Chul; Park, Kyung Chan; Yeom, Young Il; Kim, Hyun-Jung; Han, Byung Woo
Abstract
The N-Myc downstream-regulated gene (NDRG) family belongs to the alpha/beta-hydrolase fold and is known to exert various physiologic functions in cell proliferation, differentiation, and hypoxia-induced cancer metabolism. In particular, NDRG3 is closely related to proliferation and migration of prostate cancer cells, and recent studies reported its implication in lactate-triggered hypoxia responses or tumorigenesis. However, the underlying mechanism for the functions of NDRG3 remains unclear. Here, we report the crystal structure of human NDRG3 at 2.2 angstrom resolution, with six molecules in an asymmetric unit. While NDRG3 adopts the alpha/beta-hydrolase fold, complete substitution of the canonical catalytic triad residues to non-reactive residues and steric hindrance around the pseudo-active site seem to disable the alpha/beta-hydrolase activity. While NDRG3 shares a high similarity to NDRG2 in terms of amino acid sequence and structure, NDRG3 exhibited remarkable structural differences in a flexible loop corresponding to helix alpha 6 of NDRG2 that is responsible for tumor suppression. Thus, this flexible loop region seems to play a distinct role in oncogenic progression induced by NDRG3. Collectively, our studies could provide structural and biophysical insights into the molecular characteristics of NDRG3.