Lipoxin A4 Ameliorates Lipopolysaccharide-Induced A549 Cell Injury through Upregulation of N-myc Downstream-Regulated Gene-1

N-myc downstream regulated gene 1 inhibition of tumor progression in Caco2 cells

BACKGROUND

Invasion and migration are the irreversible stages of colorectal cancer (CRC). The key is to find a sensitive, reliable molecular marker that can predict the migration of CRC at an early stage. N-myc downstream regulated gene 1 (NDRG1) is a multifunctional gene that has been tentatively reported to have a strong relationship with tumor invasion and migration, however the current molecular role of NDRG1 in CRC remains unknown.

AIM

To explore the role of NDRG1 in the development of CRC.

METHODS

NDRG1 stably over-expressed Caco2 cell line was established by lentiviral infection and NDRG1 knock-out Caco2 cell line was established by CRISPR/Cas9. Furthermore, the mRNA and protein levels of NDRG1 in Caco2 cells after NDRG1 over-expression and knockout were detected by real-time polymerase chain reaction and western blot. The cell proliferation rate was measured by the cell counting kit-8 method; cell cycle and apoptosis were detected by flow cytometry; invasion and migration ability were detected by the 24-transwell method.

RESULTS

NDRG1 over-expression inhibited Caco2 proliferation and the cell cycle could be arrested at the G1/S phase when NDRG1 was over-expressed, while the number of cells in the G2 phase was significantly increased when NDRG1 was knocked out. This suggests that NDRG1 inhibited the proliferation of Caco2 cells by arresting the cell cycle in the G1/S phase. Our data also demonstrated that NDRG1 promotes early cell apoptosis. Invasion and migration of cells were extensively inhibited when NDRG1 was over-expressed.

CONCLUSION

NDRG1 inhibits tumor progression in Caco2 cells which may represent a potential novel therapeutic strategy for the treatment of CRC.

CRISPR/Cas9 Mediated Knock Down of δ-ENaC Blunted the TNF-Induced Activation of ENaC in A549 Cells

Tumor necrosis factor (TNF) is known to activate the epithelial Na⁺ channel (ENaC) in A549 cells. A549 cells are widely used model for ENaC research. The role of δ-ENaC subunit in TNF-induced activation has not been studied. In this study we hypothesized that δ-ENaC plays a major role in TNF-induced activation of ENaC channel in A549 cells which are widely used model for ENaC research. We used CRISPR/Cas 9 approach to knock down (KD) the δ-ENaC in A549 cells. Western blot and immunofluorescence assays were performed to analyze efficacy of δ-ENaC protein KD. Whole-cell patch clamp technique was used to analyze the TNF-induced activation of ENaC. Overexpression of wild type δ-ENaC in the δ-ENaC KD of A549 cells restored the TNF-induced activation of whole-cell Na⁺ current. Neither N-linked glycosylation sites nor carboxyl terminus domain of δ-ENaC was necessary for the TNF-induced activation of whole-cell Na⁺ current in δ-ENaC KD of A549 cells. Our data demonstrated that in A549 cells the δ-ENaC plays a major role in TNF-induced activation of ENaC.