| Autor: |
Mutvei AP; Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden., Landor SK; Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.; Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520, Turku, Finland., Fox R; Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden., Braune EB; Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden., Tsoi YL; Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden., Phoon YP; Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden., Sahlgren C; Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520, Turku, Finland., Hartman J; Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden., Bergh J; Department of Oncology-Pathology, Karolinska Institutet, Radiumhemmet, Breast Cancer, Cancer Theme, Karolinska University Hospital, Stockholm, Sweden.; Department of Public Health, Oxford University, Oxford, OX1 2JD, UK., Jin S; Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden. Shaobo.Jin@ki.se., Lendahl U; Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden. Urban.Lendahl@ki.se. |
| Abstrakt: |
Hyperactivation of Notch signaling and the cellular hypoxic response are frequently observed in cancers, with increasing reports of connections to tumor initiation and progression. The two signaling mechanisms are known to intersect, but while it is well established that hypoxia regulates Notch signaling, less is known about whether Notch can regulate the cellular hypoxic response. We now report that Notch signaling specifically controls expression of HIF2α, a key mediator of the cellular hypoxic response. Transcriptional upregulation of HIF2α by Notch under normoxic conditions leads to elevated HIF2α protein levels in primary breast cancer cells as well as in human breast cancer, medulloblastoma, and renal cell carcinoma cell lines. The elevated level of HIF2α protein was in certain tumor cell types accompanied by downregulation of HIF1α protein levels, indicating that high Notch signaling may drive a HIF1α-to-HIF2α switch. At the transcriptome level, the presence of HIF2α was required for approximately 21% of all Notch-induced genes: among the 1062 genes that were upregulated by Notch in medulloblastoma cells during normoxia, upregulation was abrogated in 227 genes when HIF2α expression was knocked down by HIF2α siRNA. In conclusion, our data show that Notch signaling affects the hypoxic response via regulation of HIF2α, which may be important for future cancer therapies. |
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