Cell-surface nucleolin acts as a central mediator for carcinogenic, anti-carcinogenic, and disease-related ligands.

Abstract

PURPOSE:

Cell-surface nucleolin in human gastric cancer cell lines is a receptor for TNF-α-inducing protein (Tipα) of Helicobacter pylori. The binding complex of nucleolin and Tipα is internalized into the cells and then induces tumor progression of human gastric cancer. Surface nucleolin is also a receptor of human immunodeficiency virus-1, and the anti-HIV pseudopeptide (HB-19) showed anti-carcinogenic activity in vivo. Surface nucleolin has dual functions depending on the ligands: In order to understand the mechanisms of surface nucleolin, it is necessary to review surface nucleolin and its relation to carcinogenic ligands and anti-carcinogenic ligands. Other ligands can be grouped among disease-related ligands, which is an important new topic for the prevention of various ailments.

RESULTS AND DISCUSSION:

This paper mainly deals with two ligands of surface nucleolin, Tipα and pseudopeptide HB-19. The binding complex of nucleolin and Tipα induces expression of TNF-α and chemokine genes and activates NF-κB in gastric cancer cells of humans and mice. However, when human gastric cancer cell line MKN-1 was transfected with nucleolin-targeted siRNA, the result was inhibition of cell migration and elongation induced by Tipα. The amount of surface nucleolin was reduced in membrane fraction of the nucleolin knockdown MKN-1 cells, but the amount of nucleolin in the cytosol or nuclear fractions of the cells did not change. The results indicate that surface nucleolin acts as a carcinogenic mediator for Tipα of H. pylori. In contrast, both the viral external envelop glycoprotein gp120 of HIV and the anti-HIV pseudopeptide HB-19 bind to surface nucleolin. Through this binding, treatment with HB-19 inhibited tumor development in human breast cancer cell line MDA-MB-231 and rhabdoid tumor cell line derived from Wilms's tumor in xenograft nude mouse models. The results show that surface nucleolin acts as an anti-carcinogenic mediator for HB-19.

CONCLUSION:

Based on these discrete functions of surface nucleolin, the binding complex of carcinogenic ligands and surface nucleolin seems to be competing with that of anti-carcinogenic ligands and surface nucleolin. Moreover, carcinogenic ligands derived from endogenous sources play a significant role in human cancer development, and the interaction of surface nucleolin with disease-related ligands will be a new research subject for the prevention and treatment of various ailments.

• Authors: Hirota Fujiki, Tatsuro Watanabe, Masami Suganuma
• Journal: Journal of cancer research and clinical oncology (J Cancer Res Clin Oncol) Vol. 140 Issue 5 Pg. 689-99 (May 2014) ISSN: 1432-1335 [Electronic] Germany
• PMID: 24469254 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Proteins
• HB-19 peptide
• Ligands
• Macromolecular Substances
• Peptides
• Phosphoproteins
• RNA-Binding Proteins
• Tipalpha protein, Helicobacter pylori
• Tumor Necrosis Factor-alpha
• nucleolin

Topics

• Animals
• Bacterial Proteins (genetics, metabolism)
• Carcinogenesis (genetics)
• Cell Line, Tumor
• Cell Movement (genetics)
• HIV-1 (genetics, metabolism)
• Helicobacter pylori (genetics)
• Humans
• Ligands
• Macromolecular Substances (chemistry, metabolism)
• Mice
• Peptides (chemistry, genetics, metabolism)
• Phosphoproteins (genetics, metabolism)
• Protein Binding
• RNA-Binding Proteins (genetics, metabolism)
• Stomach Neoplasms (genetics, metabolism, pathology)
• Tumor Necrosis Factor-alpha (biosynthesis, genetics)