IGF-1 Mediates PTEN Suppression and Enhances Cell Invasion and Proliferation via Activation of the IGF-1/PI3K/Akt Signaling Pathway in Pancreatic Cancer Cells

Background. Type-1 insulin-like growth factor (IGF-1) up-regulates cell proliferation and invasiveness through activation of PI3K/Akt signaling pathway. IGF-1 also down-regulates the tumor suppressor chromosome 10 (PTEN). We investigated the mechanism by which IGF-1 affects cell proliferation and invasion by suppression of PTEN phosphorylation and interaction with PI3K/PTEN/Akt/NF-kappa B signaling pathway in pancreatic cancer. Materials and Methods. The expression of IGF-1 receptor (IGF-1R) and PTEN in five pancreatic cancer cell lines was determined by RT-PCR and Western blot. Proliferation and invasion were investigated by WST-1 assay and Matrigel-double chamber assay. Pancreatic cancer cells were transfected with PTEN siRNA to investigate which signaling pathway correlates in regulation of cancer cell proliferation and invasion. Results. Five pancreatic cancer cell lines expressed PTEN and IGF-1R in mRNA and protein levels. Suppression of PTEN phosphorylation strongly enhanced cell proliferation and invasion stimulated with IGF-1 via activation of PI3K/Akt/NF-kappa B signaling pathway. In addition, knockdown of PTEN by siRNA transfection also enhanced activation of PI3K/Akt/NF-kappa B pathway, subsequently up-regulating cell invasiveness and proliferation. Conclusions. The IGF-1/PI3K/PTEN/Akt/NF-kappa B cascade may be a key pathway stimulating metastasis of pancreatic cancer cells. We suggest that interfering with the functions of IGF-1/PI3K/Akt/NF-kappa B might be a novel therapeutic approach to inhibit aggressive spread of pancreatic cancer. (C) 2010 Elsevier Inc. All rights reserved.