Claudin 1 mediates TNFα-induced gene expression and cell migration in human lung carcinoma cells.
Epithelial-mesenchymal transition (EMT) is an important mechanism in carcinogenesis. To determine the mechanisms that are involved in the regulation of EMT, it is crucial to develop new biomarkers and therapeutic targets towards cancers. In this study, when TGFβ1 and TNFα were used to induce EMT in human lung carcinoma A549 cells, we found an increase in an epithelial cell tight junction marker, Claudin 1. We further identified that it was the TNFα and not the TGFβ1 that induced the fibroblast-like morphology changes. TNFα also caused the increase in Claudin-1 gene expression and protein levels in Triton X-100 soluble cytoplasm fraction. Down-regulation of Claudin-1, using small interfering RNA (siRNA), inhibited 75% of TNFα-induced gene expression changes. Claudin-1 siRNA effectively blocked TNFα-induced molecular functional networks related to inflammation and cell movement. Claudin-1 siRNA was able to significantly reduce TNF-enhanced cell migration and fibroblast-like morphology. Furthermore, over expression of Claudin 1 with a Claudin 1-pcDNA3.1/V5-His vector enhanced cell migration. In conclusion, these observations indicate that Claudin 1 acts as a critical signal mediator in TNFα-induced gene expression and cell migration in human lung cancer cells. Further analyses of these cellular processes may be helpful in developing novel therapeutic strategies.
Latner Thoracic Surgery Research Laboratories, University Health Network Toronto General Research Institute, Toronto, Canada.
Atsushi
A
Shiozaki
Xiao-hui
XH
Bai
Grace
G
Shen-Tu
Serisha
S
Moodley
Hiroki
H
Takeshita
Shan-Yu
SY
Fung
Yingchun
Y
Wang
Shaf
S
Keshavjee
Mingyao
M
Liu
D002277:Carcinoma / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects* / Q000235:genetics; D062445:Claudin-1; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D020868:Gene Silencing; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D034741:RNA, Small Interfering / Q000378:metabolism; D015203:Reproducibility of Results; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
C568108:CLDN1 protein, human; D062445:Claudin-1; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha