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Involvement of programmed cell death 4 in transforming growth factor-beta1-induced apoptosis in human hepatocellular

H Zhang1, I Ozaki, T Mizuta

  • 1Department of Internal Medicine, Division of Hepatology and Metabolism, Saga Medical School, Saga University, Saga, Japan.

Oncogene
|May 10, 2006
PubMed

Insights

Programmed cell death 4 (PDCD4) is downregulated in human hepatocellular carcinoma (HCC). PDCD4 acts as a tumor suppressor by inducing apoptosis in HCC cells, suggesting its role in preventing liver cancer progression.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Death Research

Background:

  • Programmed cell death 4 (PDCD4) is a known tumor suppressor, but its role in human hepatocellular carcinoma (HCC) requires further investigation.
  • Understanding PDCD4's function in HCC is crucial for developing targeted therapies.

Purpose of the Study:

  • To investigate the expression levels of PDCD4 in human HCC tissues and cell lines.
  • To elucidate the role of PDCD4 in regulating apoptosis and its association with transforming growth factor-beta1 (TGF-beta1) signaling in HCC.

Main Methods:

  • Western blotting and immunohistochemical staining were used to assess PDCD4 protein levels in HCC tissues.
  • PDCD4 gene expression was manipulated in the Huh7 HCC cell line via cDNA transfection and antisense technology.
  • Apoptosis was induced and measured using characteristic markers like DNA laddering and nuclear fragmentation, alongside caspase activation and mitochondrial assays.
  • TGF-beta1 signaling pathway was modulated using TGF-beta1 treatment and Smad7 transfection.

Main Results:

  • PDCD4 protein was significantly downregulated in all tested HCC tissues compared to noncancerous liver tissue.
  • Overexpression of PDCD4 in Huh7 cells induced apoptosis, characterized by DNA fragmentation, caspase activation, and mitochondrial changes.
  • TGF-beta1 treatment increased PDCD4 expression and induced apoptosis in Huh7 cells, effects which were blocked by Smad7, an inhibitor of TGF-beta1 signaling.
  • Inhibition of PDCD4 expression rendered HCC cells resistant to TGF-beta1-induced apoptosis.

Conclusions:

  • PDCD4 functions as a proapoptotic factor in human HCC cells.
  • PDCD4 is involved in TGF-beta1-mediated apoptosis and may act as a tumor suppressor in hepatocarcinogenesis.
  • Targeting PDCD4 could be a potential therapeutic strategy for liver cancer.

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