IGFBP-3 expression in hepatocellular carcinoma involves abnormalities in TGF-β and/or Rb signaling pathways
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- Published online on: November 1, 2005 https://doi.org/10.3892/ijo.27.5.1223
- Pages: 1223-1230
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Abstract
Insulin-like growth factor binding protein-3 (IGFBP-3) is a mediator of growth suppression signals and a putative tumor suppressor gene. The growth suppression mechanisms of IGFBP-3 have not been well clarified. We examined the expression of IGFBP-3 transcripts in human hepatocellular carcinoma (HCC) and the relationship between IGFBP-3 expression and the transforming growth factor-β (TGF-β) and/or retinoblastoma (Rb) signaling pathways. In situ hybridization revealed IGFBP-3 transcripts in cancer cells in 6 of 57 (10%) HCCs, including moderately and poorly differentiated HCCs with intrahepatic metastasis. In contrast, all lung metastatic nodules of 4 HCCs showed IGFBP-3 transcripts in cancer cells. The cDNA microarray showed that genes for the TGF-β pathway and Rb were up-regulated in IGFBP-3-expressing HCCs. In 6 HCCs presenting IGFBP-3, immunohistochemical analyses showed abnormalities in the TGF-β and/or Rb pathways; the loss of phosphorylated-Smad2 was observed in 2, and overexpression of phosphorylated-Rb was observed in the remaining 4 HCCs. The present study suggests that IGFBP-3 mediates growth suppression signals via the TGF-β and/or Rb pathways in HCC.