Midkine protects hepatocellular carcinoma cells against TRAIL-mediated apoptosis through down-regulation of caspase-3 activity.

Abstract

BACKGROUND:

It is believed that midkine (MK), a heparin-binding growth factor, plays an important role in carcinogenesis. However, the biologic mechanism of MK in hepatocellular carcinoma has not been clarified to date. The objective of the current study was to investigate the antiapoptotic role of MK in a human hepatoma cell line.

METHODS:

The human hepatoma cell line HepG2 was used to study the antiapoptotic effect of MK. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/actinomycin D (ActD)-induced apoptosis was detected using a 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulphophenyl)-2H-tetrazolium monosodium salt (WST-8) assay, a caspase-3 activity assay, a caspase-8 activity assay, and flow cytometric analysis.

RESULTS:

TRAIL had a potent, dose-dependent inductive effect on cell death in HepG2 cells, for which viable cell counts decreased to 6.3% of the control count at a TRAIL concentration of 100 ng/mL in the presence of 500 ng/mL ActD. Flow cytometry was used to demonstrate that apoptosis induced by TRAIL/ActD was in fact the cause of cell death. According to the WST-8 assay, MK pretreatment resulted in the suppression of TRAIL/ActD-mediated apoptosis in HepG2 cells, although cell viability did not increase when HepG2 cells were treated with MK alone. Caspase-3 activity was down-regulated when MK was added, but caspase-8 activity was high in both the absence and presence of MK.

CONCLUSIONS:

The results of the current study indicate that MK acts as an antiapoptotic factor in HepG2 cells through the down-regulation of caspase-3 activity.

• Authors: Tomoko Ohuchida, Kohji Okamoto, Kazuhisa Akahane, Aiichiro Higure, Hidekazu Todoroki, Yukio Abe, Makoto Kikuchi, Shinya Ikematsu, Takashi Muramatsu, Hideaki Itoh
• Journal: Cancer (Cancer) Vol. 100 Issue 11 Pg. 2430-6 (Jun 01 2004) ISSN: 0008-543X [Print] United States
• PMID: 15160348 (Publication Type: Journal Article)
• Copyright: Copyright 2004 American Cancer Society.

Chemical References

• 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H tetrazolium monosodium salt
• Apoptosis Regulatory Proteins
• Carrier Proteins
• Cytokines
• Membrane Glycoproteins
• Protein Synthesis Inhibitors
• TNF-Related Apoptosis-Inducing Ligand
• TNFSF10 protein, human
• Tetrazolium Salts
• Tumor Necrosis Factor-alpha
• Midkine
• Dactinomycin
• CASP3 protein, human
• Caspase 3
• Caspases

Topics

• Apoptosis (drug effects)
• Apoptosis Regulatory Proteins
• Carcinoma, Hepatocellular (metabolism, pathology)
• Carrier Proteins (pharmacology)
• Caspase 3
• Caspases (metabolism)
• Cytokines (pharmacology)
• Dactinomycin (pharmacology)
• Down-Regulation
• Flow Cytometry
• Humans
• Liver Neoplasms (metabolism, pathology)
• Membrane Glycoproteins (metabolism)
• Midkine
• Protein Synthesis Inhibitors (pharmacology)
• TNF-Related Apoptosis-Inducing Ligand
• Tetrazolium Salts (metabolism)
• Tumor Cells, Cultured (drug effects)
• Tumor Necrosis Factor-alpha (metabolism)