The Signaling Network of Transforming Growth Factor β1, Protein Kinase Cδ, and Integrin Underlies the Spreading and Invasiveness of Gastric Carcinoma Cells

Abstract

Integrin-mediated cell adhesion and spreading enables cells to respond to extracellular stimuli for cellular functions. Using a gastric carcinoma cell line that is usually round in adhesion, we explored the mechanisms underlying the cell spreading process, separate from adhesion, and the biological consequences of the process. The cells exhibited spreading behavior through the collaboration of integrin-extracellular matrix interaction with a Smad-mediated transforming growth factor ␤1 (TGF␤1) pathway that is mediated by protein kinase C␦ (PKC␦). TGF␤1 treatment of the cells replated on extracellular matrix caused the expression and phosphorylation of PKC␦, which is required for expression and activation of integrins. Increased expression of integrins ␣2 and ␣3 correlated with the spreading, functioning in activation of focal adhesion molecules. Smad3, but not Smad2, overexpression enhanced the TGF␤1 effects. Furthermore, TGF␤1 treatment and PKC␦ activity were required for increased motility on fibronectin and invasion through matrigel, indicating their correlation with the spreading behavior. Altogether, this study clearly evidenced that the signaling network, involving the Smad-dependent TGF␤ pathway, PKC␦ expression and phosphorylation, and integrin expression and activation, regulates cell spreading, motility, and invasion of the SNU16mAd gastric carcinoma cell variant.

High glucose activates PKC-ζ and NADPH oxidase through autocrine TGF-β1 signaling in mesangial cells

“…TGF-␤ 1 has been reported to enhance the activity of isolated PKC isozymes in various cell types (28,59) and, in particular, PKC-␦ in mesangial cells (19). Differences in the incubation conditions or cell lines used could explain the more widespread PKC activation by TGF-␤ 1 observed in the present experiments compared with the study by Hayashida et al (19).…”

PKCδ and cofilin activation affects peripheral actin reorganization and cell-cell contact in cells expressing integrin α5 but not its tailless mutant

“…5E. The overexpression of DN PKC␦ in RIE1-␣5 cells abolished OXOmediated decrease in pS 3 cofilin, but the overexpression of WT PKC␦, and thereby the enhancement of pS 643 PKC␦, in RIE1-␣5/1 cells (Lee et al, 2005) decreased pS 3 cofilin upon OXO treatment, although pS 3 cofilin level in OXO-treated RIE1-␣5/1 was higher than that in OXO-treated RIE1-␣5 cells (Fig. 6A).…”

“…Next, we conversely examined if activation of PKC␦ in RIE1-␣5/1 cells facilitated cell-cell contact loss by OXO treatment. Infection of RIE1-␣5/1 cells with adenovirus for WT PKC␦ [overexpression of which enhances pS 643 PKC␦ (Lee et al, 2005)] caused cell-cell contact loss after OXO treatment (Fig. 5D).…”

Extracellular matrix-induced transforming growth factor-β receptor signaling dynamics

“…Interaction between TGF-b and collagen signaling has been described previously (Qi and Scully, 1997, 2000, and limited synergism between collagen and Smad signaling has been reported (Lee et al, 2005;Schneiderbauer et al, 2004). To date, it was unknown whether this could be applicable to other matrix molecules and the role of participating receptors and TGF-b ligand requirement was not clarified.…”