IGFBP2 is a candidate biomarker for Ink4a-Arf status and a therapeutic target for high-grade gliomas.

Abstract

The levels of insulin-like growth factor-binding protein 2 (IGFBP2) are elevated during progression of many human cancers. By using a glial-specific transgenic mouse system (RCAS/Ntv-a), we reported previously that IGFBP2 is an oncogenic factor for glioma progression in combination with platelet-derived growth factor-beta (PDGFB). Because the INK4a-ARF locus is often deleted in high-grade gliomas (anaplastic oligodendroglioma and glioblastoma), we investigated the effect of the Ink4a-Arf-null background on IGFBP2-mediated progression of PDGFB-initiated oligodendroglioma. We demonstrate here that homozygous deletion of Ink4a-Arf bypasses the requirement of exogenously introduced IGFBP2 for glioma progression. Instead, absence of Ink4a-Arf resulted in elevated endogenous tumor cell IGFBP2. An inverse relationship between p16(INK4a) and IGFBP2 expression was also observed in human glioma tissue samples and in 90 different cancer cell lines by using Western blotting and reverse-phase protein lysate arrays. When endogenous IGFBP2 expression was attenuated by an RCAS vector expressing antisense IGFBP2 in our mouse model, a decreased incidence of anaplastic oligodendroglioma as well as prolonged survival was observed. Thus, p16(INK4a) is a negative regulator of the IGFBP2 oncogene. Loss of Ink4a-Arf results in increased IGFBP2, which contributes to glioma progression, thereby implicating IGFBP2 as a marker and potential therapeutic target for Ink4a-Arf-deleted gliomas.

• Authors: Lynette M Moore, Kristen M Holmes, Sarah M Smith, Ying Wu, Elena Tchougounova, Lene Uhrbom, Raymond Sawaya, Janet M Bruner, Gregory N Fuller, Wei Zhang
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 106 Issue 39 Pg. 16675-9 (Sep 29 2009) ISSN: 1091-6490 [Electronic] United States
• PMID: 19805356 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Cdkn2a protein, mouse
• Cyclin-Dependent Kinase Inhibitor p16
• Insulin-Like Growth Factor Binding Protein 2
• Proto-Oncogene Proteins c-sis

Topics

• Animals
• Brain Neoplasms (drug therapy, metabolism)
• Cell Line, Tumor
• Cyclin-Dependent Kinase Inhibitor p16 (genetics, metabolism)
• Glioma (drug therapy, metabolism)
• Humans
• Insulin-Like Growth Factor Binding Protein 2 (metabolism)
• Mice
• Mice, Knockout
• Mice, Transgenic
• Proto-Oncogene Proteins c-sis (metabolism)