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Dickkopf-1 is down-regulated by MYCN and inhibits neuroblastoma cell proliferation
Arjen Koppen1, Rachida Ait-Aissa, Saskia Hopman
1Department of Human Genetics, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands.
Abstract:
Neuroblastomas are tumors of the developing peripheral sympathetic nervous system, which originates from the neural crest. Twenty percent of neuroblastomas show amplification of the MYCN oncogene, which correlates with poor prognosis. The MYCN transcription factor can activate and repress gene expression. To broaden our insight in the spectrum of genes down-regulated by MYCN, we generated gene expression profiles of the neuroblastoma cell lines SHEP-21N and SKNAS-NmycER, in which MYCN activity can be regulated. In this study, we show that MYCN suppresses the expression of Dickkopf-1 (DKK1) in both cell lines. DKK1 is a potent inhibitor of the wnt/beta-catenin signalling cascade, which is known to function in neural crest cell migration. We generated a DKK1 inducible cell line, IMR32-DKK1, which showed impaired proliferation upon DKK1 expression. Surprisingly, DKK1 expression did not inhibit the canonical wnt/beta-catenin signalling, suggesting a role of DKK1 in an alternative route of the wnt pathway. Gene expression profiling of two IMR32-DKK1 clones showed that only a few genes, amongst which SYNPO2, were up-regulated by DKK1. SYNPO2 encodes an actin-binding protein and was previously found to inhibit proliferation and invasiveness of prostate cancer cells. These results suggest that MYCN might stimulate cell proliferation by inhibiting the expression of DKK1. DKK1 might exert part of its growth suppressive effect by induction of SYNPO2 expression.
Insights
MYCN oncogene amplification in neuroblastoma suppresses Dickkopf-1 (DKK1) expression. DKK1 inhibits neuroblastoma cell proliferation, potentially via SYNPO2, suggesting a new therapeutic target for this pediatric cancer.
Area of Science:
- Oncology
- Molecular Biology
- Developmental Biology
Background:
- Neuroblastomas are pediatric cancers originating from the neural crest.
- MYCN oncogene amplification occurs in 20% of neuroblastomas, correlating with poor prognosis.
- MYCN acts as a transcription factor, regulating both gene activation and repression.
Purpose of the Study:
- To identify genes repressed by MYCN in neuroblastoma.
- To investigate the role of Dickkopf-1 (DKK1) in MYCN-driven neuroblastoma.
- To explore potential therapeutic strategies targeting the MYCN-DKK1 axis.
Main Methods:
- Gene expression profiling of neuroblastoma cell lines with regulated MYCN activity (SHEP-21N, SKNAS-NmycER).
- Generation of a DKK1-inducible neuroblastoma cell line (IMR32-DKK1).
- Analysis of gene expression changes upon DKK1 induction.
Main Results:
- MYCN was found to suppress DKK1 expression in neuroblastoma cells.
- DKK1 expression impaired neuroblastoma cell proliferation.
- DKK1's growth suppressive effect may involve alternative Wnt pathway signaling and SYNPO2 induction.
Conclusions:
- MYCN may promote neuroblastoma proliferation by down-regulating DKK1.
- DKK1, potentially through SYNPO2, exhibits anti-proliferative effects in neuroblastoma.
- Targeting the MYCN-DKK1 pathway presents a potential therapeutic avenue for neuroblastoma.
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