EGF receptor function is required in late G₁ for cell cycle progression induced by bombesin and bradykinin

Abstract

We examined the role of epidermal growth factor (EGF) receptor (EGFR) tyrosine kinase activation in G protein-coupled receptor (GPCR) agonist-induced mitogenesis in Swiss 3T3 and Rat-1 cells. Addition of EGFR tyrosine kinase inhibitors (e.g., tyrphostin AG-1478) abrogated bombesin-induced extracellular signal-regulated kinase (ERK) activation in Rat-1 cells but not in Swiss 3T3 cells, indicating the importance of cell context in determining the role of EGFR in ERK activation. In striking contrast, treatment with tyrphostin AG-1478 markedly (~70%) inhibited DNA synthesis induced by bombesin in both Swiss 3T3 and Rat-1 cells. Similar inhibition of bombesin-induced DNA synthesis in Swiss 3T3 cells was obtained using four structurally different inhibitors of EGFR tyrosine kinase. Furthermore, kinetic analysis indicates that EGFR function is necessary for bombesin-induced mitogenesis in mid-late G(1) in both Swiss 3T3 and Rat-1 cells. Our results indicate that EGFR kinase activity is necessary in mid-late G(1) for promoting the accumulation of cyclins D1 and E and implicate EGFR function in the coupling of GPCR signaling to the activation of the cell cycle.

Bombesin, Lysophosphatidic Acid, and Epidermal Growth Factor Rapidly Stimulate Focal Adhesion Kinase Phosphorylation at Ser-910

“…MAPK (ERK-1), a response mediated through PKC in Swiss 3T3 cells (43,55,56). We verified that under our experimental conditions, treatment of the cells with either GF I or Ro 31-8220 or chronic exposure to PDB not only blocked FAK Ser-910 phosphorylation but also prevented ERK activation (Fig.…”

Protein Kinase D Potentiates DNA Synthesis Induced by Gq-coupled Receptors by Increasing the Duration of ERK Signaling in Swiss 3T3 Cells

“…EGF does not induce any significant increase in the phosphorylation or catalytic activity of PKD in Swiss 3T3 cells (53), but stimulates ERK1/2 activation through a Ras-dependent, PKC-independent pathway in these cells (86). Here, we demonstrate that the duration of ERK/RSK activation induced by EGF in Swiss 3T3-PKD.GFP cells was identical to that generated by this growth factor in Swiss 3T3-GFP cells.…”

Mitogenic effects of gastrin-releasing peptide in head and neck squamous cancer cells are mediated by activation of the epidermal growth factor receptor

“…It is generally believed that MAPK activation mediated through GPCR/EGFR drives cellular proliferation (Sharif et al, 1997;Castagliuolo et al, 2000). However, Santiskulvong et al showed that an EGFRdependent, but MAPK-independent pathway could also mediate the mitogenic effects of GPCR activation (Santiskulvong et al, 2001).…”

“…In noncancer cell lines (rodent Rat-1 and Swiss 3T3 fibroblasts), bombesin has also been reported to induce EGFR-dependent DNA synthesis (Santiskulvong et al, 2001). However, bombesin-or bradykinininduced EGFR-dependent DNA synthesis was believed to be MAPK-independent (Santiskulvong et al, 2001).…”

“…GRP has been reported to induce p44/42-MAPK activation via either an EGFR-dependent mechanism or an EGFR-independent mechanism in Rat-1 and Swiss 3T3 fibroblasts, respectively (Santiskulvong et al, 2001). Therefore, we examined if EGFR activation mediated GRP-induced activation of p44/42-MAPK in HNSCC cells.…”