EGF rapidly translocates tight junction proteins from the cytoplasm to the cell–cell contact via protein kinase C activation in TMK-1 gastric cancer cells

Abstract

Tight junctions are commonly disrupted in cancer cells, including gastric cancer. Various growth factors have been reported to affect the localization of tight junction-associated proteins such as ZO-1 and occludin. We investigated the effect of epidermal growth factor (EGF), a growth factor that is often overexpressed in gastric cancer, and fetal bovine serum (FBS) on the localization of ZO-1 and occludin in a gastric cancer cell line. In the poorly differentiated gastric cancer cell line TMK-1, immunohistochemistry demonstrated that ZO-1 and occludin were predominantly localized to the cytoplasm, although there was some weak expression at the cell-cell contact. When the medium was replaced with fresh medium containing 10% FBS, ZO-1 and occludin were rapidly translocated from the cytosol to the cell-cell contact. A similar effect was seen in EGF exposure. These effects induced by FBS or EGF were attenuated in the presence of protein kinase C (PKC) inhibitors calphostin C and bisindolylmaleimide I, but not another PKC inhibitor Gö6976, PD98059 (MAPK inhibitor), LY294002 (PI3 kinase inhibitor) or KT5720 (protein kinase A inhibitor). These results suggest that serum-derived factors, including EGF, can rapidly alter the localization of ZO-1 and occludin via a protein kinase C signaling pathway in TMK-1 gastric cancer cells.

LXA4stimulates ZO-1 expression and transepithelial electrical resistance in human airway epithelial (16HBE14o-) cells

“…In contrast, in our study, both PKC inhibitors used abolished the stimulatory effect of LXA 4 on ZO-1 staining at the plasma membrane, indicating the involvement of PKC in the stimulatory effect of LXA 4 on ZO-1 at the cell-to-cell contact. This was consistent with other studies showing that PKC activation is involved in the rapid translocation of tight junction proteins from the cytoplasm to the membrane (15,23,50,53,56,57). In MDCK, PKC inhibition antagonized the TER increase during a calcium switch (50).…”

“…In MDCK, PKC inhibition antagonized the TER increase during a calcium switch (50). In addition, known agonists of PKC rapidly stimulated the TER and the translocation of tight junction proteins from the cytoplasm to cell-cell contact in TMK-1 gastric cancer cells and in T84 colonic epithelia (56,57).…”

Tight junctions in cancer metastasis

“…In the poorly differentiated gastric cancer cell line TMK-1, ZO-1 and occludin have been shown to be predominantly localized to the cytoplasm, although there is some weak expression at the cell-cell contact (120). Epidermal growth factor (EGF), a growth factor that is often overexpressed in gastric cancer causes ZO-1 and occludin to be rapidly translocated from the cytosol to the cell-cell contact.…”

Lithium reduces tumorigenic potential in response to EGF signaling in human colorectal cancer cells

“…For example, it has been demonstrated that EGF modulates TJs in a very selective way; while EGF induces the synthesis of claudin-4 through the ERK1/2 pathway, it inhibits that of claudin-2 (4,12,13). A number of signaling events induced by EGF have also been linked to changes in cell morphology, including plasma membrane ruffling and cell rounding, both of which are required for cancer progression (14). The aberrant activation of EGFR can affect cell-cell adhesion by disrupting the association between E-cadherin and β-catenin, leading to a loss of cell differentiation and increased rates of proliferation and migration, all of which are known hallmarks of cancer progression (15).…”