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Cancer Res. 2016 May 1;76(9):2813-23. doi: 10.1158/0008-5472.CAN-15-1011. Epub 2016 Mar 15.

MIF Maintains the Tumorigenic Capacity of Brain Tumor-Initiating Cells by Directly Inhibiting p53.

Author information

1
Department of Neurosurgery, Keio University School of Medicine, Tokyo, Japan.
2
Department of Physiology, Keio University School of Medicine, Tokyo, Japan.
3
Division of Cellular Signaling, Institute for Advanced Medical Research, Keio University School of Medicine, Tokyo, Japan.
4
Division of Gene Regulation, Institute for Advanced Medical Research, Keio University School of Medicine, Tokyo, Japan.
5
Department of Neurosurgery, Keio University School of Medicine, Tokyo, Japan. todam@z2.keio.jp.

Abstract

Tumor-initiating cells thought to drive brain cancer are embedded in a complex heterogeneous histology. In this study, we isolated primary cells from 21 human brain tumor specimens to establish cell lines with high tumorigenic potential and to identify the molecules enabling this capability. The morphology, sphere-forming ability upon expansion, and differentiation potential of all cell lines were indistinguishable in vitro However, testing for tumorigenicity revealed two distinct cell types, brain tumor-initiating cells (BTIC) and non-BTIC. We found that macrophage migration inhibitory factor (MIF) was highly expressed in BTIC compared with non-BTIC. MIF bound directly to both wild-type and mutant p53 but regulated p53-dependent cell growth by different mechanisms, depending on glioma cell line and p53 status. MIF physically interacted with wild-type p53 in the nucleus and inhibited its transcription-dependent functions. In contrast, MIF bound to mutant p53 in the cytoplasm and abrogated transcription-independent induction of apoptosis. Furthermore, MIF knockdown inhibited BTIC-induced tumor formation in a mouse xenograft model, leading to increased overall survival. Collectively, our findings suggest that MIF regulates BTIC function through direct, intracellular inhibition of p53, shedding light on the molecular mechanisms underlying the tumorigenicity of certain malignant brain cells. Cancer Res; 76(9); 2813-23.

PMID:
26980763
DOI:
10.1158/0008-5472.CAN-15-1011
[Indexed for MEDLINE]
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