Effect of Epigallocatechin-3-Gallate on PMA-Induced MUC5B Expression in Human Airway Epithelial Cells

Analysis of naproxen activation of cell death pathways in Colo320 cells

Colorectal cancer is a life-threatening and prevalent type of cancer. However, a number of current treatments have serious side effects, which increase the need for alternatives. Non-steroidal anti-inflammatory drugs have potential chemopreventive capabilities. The present study aimed to confirm this, as well as to investigate potential pathways and reasons for this trait. To accomplish this, cancerous Colo320 and healthy CCD-18 cells were treated with various concentrations of naproxen sodium (NS). A caspase-3 assay revealed a statistically significant increase in caspase-3 activity in Colo320 cells (300%; P<0.01), but not in CCD-18 cells. This chemical was also associated with a significant decrease in Colo320 cell survival (-72.888%; P<0.01), but not CCD-18 cell survival. Furthermore, NS was found to significantly decrease the migration of Colo320 cells (86.58%; P<0.01). Finally, RNA sequencing of cells treated with NS revealed the statistically significant downregulation of the mucin 5B, oligomeric mucus/gel-forming, S100 calcium binding protein A9 and mucin 5AC, oligomeric mucus/gel-forming genes, which are upregulated in colorectal cancer and are known to contribute to cancer proliferation, stemness and drug resistance. These novel biological pathway results were further confirmed using ELISAs. The present study identified a novel molecular mechanism of the anti-colorectal cancer activity of NS.

Pepsin exposure in a non-acidic environment upregulates mucin 5AC (MUC5AC) expression via matrix metalloproteinase 9 (MMP9)/nuclear factor κB (NF-κB) in human airway epithelial cells

BACKGROUND

Gastric reflux (GR) is a backflow of gastric content to the aerodigestive tract. GR was previously found to be associated with inflammatory airway diseases and a potential cause of airway remodeling. Chronic exposure to gastric content may induce damage from nose to lung, because digestive enzymes and acidity are toxic to airway epithelial cells. Recently, the toxicity of pepsin in a non-acidic environment was found to increase proinflammatory cytokines and receptors in the epithelium of the aerodigestive tract. However, the effect of pepsin in non-acidic conditions on mucin expression has not been investigated in human airway epithelial cells. The purpose of this study was to evaluate the effect of pepsin on mucin 5AC (MUC5AC) expression in upper and lower airway epithelial cells as an important potential factor of non-acidic GR-related airway inflammation.

METHODS

In NCI-H292 cells and human nasal epithelial cells (HNEpCs), the effects and signaling pathways of pepsin on MUC5AC expression were examined using reverse-transcription polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassay, zymography, Western blot, and immunofluorescence staining.

RESULTS

Pepsin increased MUC5AC expression in non-acidic condition of NCI-H292 cells and HNEpCs. Further, pepsin activated matrix metalloproteinase 9 (MMP9) and phosphorylated nuclear factor κB (NF-κB). Moreover, inhibitors of MMP9 and NF-κB significantly attenuated pepsin-induced MUC5AC expression, and the knockdown of NF-κB by small interfering RNA (siRNA) significantly blocked pepsin-induced MUC5AC expression in human airway epithelial cells.

CONCLUSION

These findings suggest that pepsin increased MUC5AC expression in non-acidic conditions via the activation of MMP9 and NF-κB in human airway epithelial cells.