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Role of growth factors in pancreatic cancer
1Department of Medicine, University of California at Irvine, Irvine, California 92697, USA.
Abstract:
Human pancreatic cancers overexpress a number of important tyrosine growth factor receptors and their ligands. These include the epidermal growth factor (EGF) receptor (EGFR) and related receptors, multiple ligands that bind to EGFR, certain fibroblast growth factors (FGF) receptors (FGFR) and ligands, and insulin-like growth factor I (IGF-I) and its receptor. The excessive activation of mitogenic signaling cascades that are modulated by these overexpressed ligands and receptors is compounded by the presence of mutations in the K-ras oncogene. Pancreatic cancers also overexpress transforming growth factor betas (TGF-betas) that usually inhibit the growth of epithelial cells. Pancreatic cancers, however, underexpress the type I TGF-beta receptor and harbor mutations in the smad4 gene, alterations that prevent TGF-betas from inhibiting cancer cell growth but that do not confer onto pancreatic actions that promote cancer growth in vivo. Together, these perturbations confer onto pancreatic cancer cells a tremendous growth advantage.
Insights
Human pancreatic cancers exhibit significant overexpression of growth factor receptors and ligands, alongside K-ras mutations. These alterations, coupled with impaired TGF-beta signaling, grant cancer cells a substantial growth advantage.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Signaling Pathways
Background:
- Human pancreatic cancers are characterized by the overexpression of key tyrosine growth factor receptors and their ligands.
- These include epidermal growth factor (EGF) receptor (EGFR), fibroblast growth factor (FGF) receptors (FGFR), and insulin-like growth factor I (IGF-I) receptor.
Purpose of the Study:
- To investigate the molecular mechanisms driving the aggressive growth of human pancreatic cancers.
- To understand the role of growth factor signaling and transforming growth factor-betas (TGF-betas) in pancreatic tumorigenesis.
Main Methods:
- Analysis of overexpression of growth factor receptors and ligands in pancreatic cancer.
- Investigation of mutations in the K-ras oncogene and alterations in the TGF-beta signaling pathway, including type I TGF-beta receptor and smad4 gene mutations.
Main Results:
- Pancreatic cancers show overexpression of EGFR, FGFR, and IGF-I receptor pathways, leading to excessive activation of mitogenic signaling.
- Mutations in the K-ras oncogene compound the effects of growth factor signaling.
- Despite overexpression of TGF-betas, pancreatic cancers exhibit underexpression of the type I TGF-beta receptor and smad4 mutations, abrogating growth inhibition and contributing to uncontrolled proliferation.
Conclusions:
- The combination of overactive growth factor signaling and impaired TGF-beta pathway contributes to a significant growth advantage in pancreatic cancer cells.
- These molecular alterations are critical drivers of pancreatic cancer development and progression.