Adenovirus siMDM2 and NDRG2 Gene Therapy Inhibits Cell Proliferation and Induces Apoptosis of Squamous Cell Carcinoma

NDRG2 Deficiency Exacerbates UVB-Induced Skin Inflammation and Oxidative Stress Damage

UVB radiation induces inflammatory and oxidative stress responses, contributing to skin damage, yet the underlying mechanisms are not fully understood. N-Myc downstream-regulated gene 2 (NDRG2), an emerging stress-associated gene, remains unexplored in UVB-induced skin injury. In this study, we detected skin NDRG2 expression after UVB irradiation for the first time and further used Ndrg2 knockout mice to clarify the role of NDRG2 in UVB-induced skin injury. Three-month-old male Ndrg2+/+ and Ndrg2-/- mice (16-18g) were exposed to UVB to induce acute skin damage, and then dorsal skin samples were collected for subsequent analyses. UVB-induced skin damage was scored. Western Blot Analysis, immunofluorescence (IF) double labeling, and immunohistochemistry (IHC) were employed to assess NDRG2 expression and/or distribution. The concentrations of TNF-α, IL-6, IL-1β, MPO, MMP8, superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) were quantitatively assessed using enzyme-linked immunosorbent assay (ELISA). Hematoxylin and eosin (HE) staining were employed to determine pathological changes. RNA sequencing and analysis were performed to estimate transcript expression levels and analyze mRNA expression. DESeq2 software was employed to identify differentially expressed genes (DEGs). DEGs were visualized using volcanic and heat maps. Gene Ontology (GO) functions and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were analyzed to identify primary biological functions, metabolic pathways, or signal transduction pathways associated with DEGs. UVB-challenged Ndrg2-/- mice exhibited significantly exacerbated skin damage (erythema, edema, and erosion), neutrophil infiltration, and apoptosis compared to Ndrg2+/+ mice. Furthermore, UVB-challenged Ndrg2-/- mice displayed significantly elevated pro-inflammatory cytokines, myeloperoxidase (MPO), matrix metalloproteinase-8 (MMP8), and reduced antioxidant expression. RNA sequencing identified 1091 significantly differentially expressed genes enriched in inflammation, immune response, and oxidative stress pathways. In conclusion, the deficiency of Ndrg2 markedly exacerbated UVB-induced skin damage by promoting inflammatory responses and inhibiting antioxidant responses. This suggests that stabilizing NDRG2 expression holds promise as a therapeutic strategy for protecting against UVB-induced skin damage.

N-myc Downstream-Regulated Gene 2 (NDRG2) Function as a Positive Regulator of Apoptosis: A New Insight into NDRG2 as a Tumor Suppressor

N-myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor gene that increases tumor sensitivity to anticancer drugs, slows tumor progression, and inhibits metastasis. NDRG2 is suppressed in various aggressive tumor positions, whereas NDRG2 expression is associated with patient prognosis, such as an improved survival rate. In this review, we summarize the tumor suppressor mechanism of NDRG2 and provide information on the function of NDRG2 concerning the susceptibility of cells to apoptosis. NDRG2 increases the susceptibility to apoptosis in various physiological environments of cells, such as development, hypoxia, nutrient deprivation, and cancer drug treatment. Although the molecular and cell biological mechanisms of NDRG2 have not been fully elucidated, we provide information on the mechanisms of NDRG2 in relation to apoptosis in various environments. This review can assist the design of research regarding NDRG2 function and suggests the potential of NDRG2 as a molecular target for cancer patients.

NDRG2 suppresses proliferation, migration, invasion and epithelial-mesenchymal transition of esophageal cancer cells through regulating the AKT/XIAP signaling pathway

N-Myc downstream-regulated gene 2 (NDRG2) has recently revealed as a candidate tumor suppressor gene. To inhibit tumor growth and decrease morbidity of esophageal cancer (EC), this study aims to test the hypothesis that the upregulation of NDRG2 may suppress proliferation, invasion, migration and epithelial-mesenchymal transition (EMT) of EC cells by regulating the AKT/XIAP signaling pathway. Immunohistochemistry was conducted for the identification of NDRG2, protein kinase B (p-AKT), X-linked inhibitor of apoptosis protein (XIAP) in EC tissues. To identify the regulatory mechanism of NDRG2 on the AKT/XIAP signaling pathway and EMT in EC, over-expressed lentiviral vector and shRNA were applied for up-regulating and interfering NDRG2 expression, and a series of determinations on the biological behavior of EC cells were performed to validate this regulation action. The results of immunohistochemistry showed NDRG2 was lowly expressed in EC tissues while p-AKT and XIAP are highly expressed. Over-expression of NDRG2 suppresses the proteins related to AKT/XIAP signaling pathway and EMT. Besides, a series of determinations shows the proliferation, migration and invasion of TE-13 cells were suppressed by over-expressed NDRG2, while the cell cycle progression was blocked and cell apoptosis was promoted. And in vivo experiment also demonstrated NDRG2 could inhibit tumor growth. Our findings demonstrate over-expression of NDRG2 works as tumor suppressive role in EC through its effects on inhibition of cell migration, invasion, and EMT by inhibiting the AKT/XIAP signaling pathway.

NDRG2 contributes to cisplatin sensitivity through modulation of BAK-to-Mcl-1 ratio

The downregulation of N-Myc downstream-regulated gene 2 (NDRG2) is known to be associated with the progression and poor prognosis of several cancers. Sensitivity to anti-cancer may be associated with a good prognosis in cancer patients, and NDRG2, which is induced by p53, sensitizes the cells to chemotherapy. However, the unique function of NDRG2 as an inducer of apoptosis under chemotreatment has not been sufficiently studied. In this study, we investigated the role of NDRG2 in chemo-sensitivity, focusing on cisplatin in U937 histiocytic lymphoma, which has the loss-of-functional mutation in p53. NDRG2 promoted the sensitivity to cisplatin through the modulation of the BAK-to-Mcl-1 ratio. The degradation of Mcl-1 and increase in BAK were mediated by JNK activation and the eIF2α/p-eIF2α pathway, respectively, which depended on PKR activation in NDRG2-overexpressed U937 (U937-NDRG2) cells. NOX5 was highly expressed in U937-NDRG2 cells and contributed to ROS production after cisplatin treatment. ROS scavenging or NOX5-knockdown successfully inhibited the sensitivity of U937-NDRG2 cells to cisplatin. Taken together, these findings indicate that NDRG2 contributed to the increased sensitivity to ciplatin through the modulation of Bak-to-Mcl-1 ratio regulated by NOX5-ROS-PKR pathway; therefore, we suggest that NDRG2 may be a molecular target for improving the efficacy of drug treatment in cancer patients.