Original Article
Copyright ©2010 Baishideng. All rights reserved
World J Gastroenterol. Apr 21, 2010; 16(15): 1854-1858
Published online Apr 21, 2010. doi: 10.3748/wjg.v16.i15.1854
Insulin-like growth factor-I receptor in proliferation and motility of pancreatic cancer
Minoru Tomizawa, Fuminobu Shinozaki, Takao Sugiyama, Shigenori Yamamoto, Makoto Sueishi, Takanobu Yoshida
Minoru Tomizawa, Department of Gastroenterology, National Hospital Organization Shimoshizu Hospital, 934-5 Shikawatashi, Yotsukaido City, Chiba 284-0003, Japan
Fuminobu Shinozaki, Department of Radiology, National Hospital Organization Shimoshizu Hospital, 934-5 Shikawatashi, Yotsukaido City, Chiba 284-0003, Japan
Takao Sugiyama, Makoto Sueishi, Department of Rheumatology, National Hospital Organization Shimoshizu Hospital, 934-5 Shikawatashi, Yotsukaido City, Chiba 284-0003, Japan
Shigenori Yamamoto, Department of Pediatrics, National Hospital Organization Shimoshizu Hospital, 934-5 Shikawatashi, Yotsukaido City, Chiba 284-0003, Japan
Takanobu Yoshida, Department of Internal Medicine, National Hospital Organization Shimoshizu Hospital, 934-5 Shikawatashi, Yotsukaido City, Chiba 284-0003, Japan
Author contributions: Tomizawa M, Shinozaki F and Sugiyama T performed the majority of the experiments; Yamamoto S and Sueishi M were involved in editing the manuscript; Yoshida T performed the statistical analysis.
Correspondence to: Dr. Minoru Tomizawa, Department of Gastroenterology, National Hospital Organization Shimoshizu Hospital, 934-5 Shikawatashi, Yotsukaido City, Chiba 284-0003, Japan. nihminor-cib@umin.ac.jp
Telephone: +81-43-4222511 Fax: +81-43-4213007
Received: December 10, 2009
Revised: January 18, 2010
Accepted: January 25, 2010
Published online: April 21, 2010
Abstract

AIM: To develop a molecular therapy for pancreatic cancer, the insulin-like growth factor-I (IGF-I) signaling pathway was analyzed.

METHODS: Pancreatic cancer cell lines (MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4) were cultured in media with 10 mL/L fetal bovine serum. Western blotting analysis was performed to clarify the expression of IGF-I receptor (IGF-IR). Picropodophyllin (PPP), a specific inhibitor of IGF-IR, LY294002, a specific inhibitor of phosphatidylinositol 3 kinase (PI3K), and PD98059, a specific inhibitor of mitogen-activated protein kinase, were added to the media. After 72 h, a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay was performed to analyze cell proliferation. A wound assay was performed to analyze cell motility with hematoxylin and eosin (HE) staining 48 h after addition of each inhibitor.

RESULTS: All cell lines clearly expressed not only IGF-IR but also phosphorylated IGF-IR. PPP significantly suppressed proliferation of MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4 cells to 36.9% ± 2.4% (mean ± SD), 30.9% ± 5.5%, 23.8% ± 3.9%, 37.1% ± 5.3%, 10.4% ± 4.5%, 52.5% ± 4.5% and 22.6% ± 0.4%, at 2 μmol/L, respectively (P < 0.05). LY294002 significantly suppressed proliferation of MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4 cells to 44.4% ± 7.6%, 32.9% ± 8.2%, 53.9% ± 8.0%, 52.8% ± 4.0%, 32.3% ± 4.2%, 51.8% ± 4.5%, and 30.6% ± 9.4%, at 50 μmol/L, respectively (P < 0.05). PD98059 did not significantly suppress cell proliferation. PPP at 2 μmol/L suppressed motility of MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4 cells to 3.0% ± 0.2%, 0%, 0%, 2.0% ± 0.1%, 5.0% ± 0.2%, 3.0% ± 0.1%, and 5.0% ± 0.2%, respectively (P < 0.05). LY294002 at 50 μmol/L suppressed motility of MIA-Paca2, NOR-P1, PANC-1, PK-45H, PK-1, PK-59 and KP-4 to 3.0% ± 0.2%, 0%, 3.0% ± 0.2%, 0%, 0%, 0% and 3% ± 0.1%, respectively (P < 0.05). PD980509 at 20 μmol/L did not suppress motility. Cells were observed by microscopy to analyze the morphological changes induced by the inhibitors. Cells in medium treated with 2 μmol/L PPP or 50 μmol/L LY294002 had pyknotic nuclei, whereas those in medium with 20 μmol/L PD98059 did not show apoptosis.

CONCLUSION: IGF-IR and PI3K are good candidates for molecular therapy of pancreatic cancer.

Keywords: Insulin-like growth factor-I receptor; Phosphatidylinositol 3 kinase; Pancreatic neoplasms