Role of GLI-1 in epidermal growth factor-induced invasiveness of ARCaPE prostate cancer cells

Abstract

Abstract. Epidermal growth factor (EGF) signaling and Hedgehog (HH) signaling are both involved in prostate cancer (PCa) progression, yet the mechanisms through which these two pathways are synergistically linked require elucidation. In the present study, we aimed to ascertain how EGF and the HH signaling transcription factor GLI-1 are linked in prostate cancer invasiveness. ARCaP human prostate cancer cells, which included ARCaP E and ARCaP M cells, were used as a model in the present study. The expression of EGF receptor (EGFR) and the HH signaling transcriptional factor GLI-1 were detected in ARCaP E cells by immunofluorescence, and the ARCaP E cells were treated with human recombinant EGF protein (hrEGF) for 4 consecutive days in vitro. Transwell invasion assays were performed in the ARCaP E cells following treatment with DMSO (vehicle control), hrEGF, GATN61 (GLI-1-specific inhibitor), hrEGF plus GANT61 and in the ARCaP M cells. The expression of phosphorylated extracellular signal regulated kinase (p-ERK), total ERK and GLI-1 was detected by western blotting in ARCaP E cells at different timepoints following treatment with hrEGF. The expression of EGFR and GLI-1 was detected in ARCaP E cells, which exhibited a cobblestone-like morphology, while after treatment with hrEGF, the cell morphology was altered to a spindle-shaped mesenchymal cell morphology. Transwell invasion assays demonstrated that hrEGF dramatically enhanced the invasive capability of the ARCaP E cells (P<0.05). Additionally, western blot assay demonstrated that the expression levels of p-ERK and GLI-1 in ARCaP E cells increased in a time-dependent manner after treatment with hrEGF (P<0.05); however, the expression levels of total ERK in the cells remained relatively unchanged. It also demonstrated that the GLI-1 inhibitor GANT61 could reverse the enhanced invasive effect induced by EGF in ARCaP E cells (P<0.05). Our preliminary in vitro study showed that EGF signaling may increase the invasive capability of ARCaP E human prostate cancer cells via upregulation of p-ERK and the HH signaling transcriptional factor GLI-1. Additionally, this enhanced cell invasive effect was reversed by a GLI-1-specific inhibitor in vitro. Consequently, it indicates that both EGF and HH signaling are synergistically involved in the progression of human prostate cancer ARCaP cells, and GLI-1 may be one of the important effectors, which is activated by EGF downstream signaling, to promote the invasiveness of ARCaP E prostate cancer cells.

Eotaxin-1 promotes prostate cancer cell invasion via activation of the CCR3-ERK pathway and upregulation of MMP-3 expression

“…Eotaxin-1 induces the activation of ERK1/2 in prostate cancer cells. The ERK pathway is essential to the invasion and metastasis of prostate cancer (14). Here, we detected the phosphorylation of ERK1/2 following eotaxin-1 treatment by western blotting.…”

Mitogen-activated protein kinases and Hedgehog-GLI signaling in cancer: A crosstalk providing therapeutic opportunities?

“…Authors hypothesized that the mediator of EGF and HH pathway crosstalk is ERK1/2 through an unknown mechanism [125].…”

Gli1 Protein Regulates the S-phase Checkpoint in Tumor Cells via Bid Protein, and Its Inhibition Sensitizes to DNA Topoisomerase 1 Inhibitors

“…Therefore, agents that target Smoothened (Smo) or upstream targets of the Hh pathway remain largely ineffective in these cancers (15,16), suggesting the importance of the development of small molecule inhibitors that may target Glis, particularly Gli1. Although Gli1 is often an up-regulated Hh component in many tumors, identification of the signaling mechanisms it regulates in tumor cells is critical in developing effective therapeutic modalities (17)(18)(19)(20). Recently, several studies indicated the influence of Hh/Gli1 signaling on DNA damage response (DDR) 3 and repair pathways to promote more aggressive disease and tumor resistance to therapeutics (21)(22)(23)(24).…”