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Mol Cancer Res. 2008 Feb;6(2):282-90. doi: 10.1158/1541-7786.MCR-07-0377.

Poly(ADP-ribose) polymerase 1 promotes tumor cell survival by coactivating hypoxia-inducible factor-1-dependent gene expression.

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  • 1Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland.


Hypoxia-inducible factor 1 (HIF-1) is the key transcription factor regulating hypoxia-dependent gene expression. Lack of oxygen stabilizes HIF-1, which in turn modulates the gene expression pattern to adapt cells to the hypoxic environment. Activation of HIF-1 is also detected in most solid tumors and supports tumor growth through the expression of target genes that are involved in processes like cell proliferation, energy metabolism, and oxygen delivery. Poly(ADP-ribose) polymerase 1 (PARP1) is a chromatin-associated protein, which was shown to regulate transcription. Here we report that chronic myelogenous leukemia cells expressing small interfering RNA against PARP1, which were injected into wild-type mice expressing PARP1, showed tumor growth with increased levels of necrosis, limited vascularization, and reduced expression of GLUT-1. Of note, PARP1-deficient cells showed a reduced HIF-1 transcriptional activation that was dependent on PARP1 enzymatic activity. PARP1 neither influenced binding of HIF-1 to its hypoxic response element nor changed HIF-1alpha protein levels in hypoxic cells. However, PARP1 formed a complex with HIF-1alpha through direct protein interaction and coactivated HIF-1alpha-dependent gene expression. These findings provide convincing evidence that wild-type mice expressing PARP1 cannot compensate for the loss of PARP1 in tumor cells and strengthen the importance of the role of PARP1 as a transcriptional coactivator of HIF-1-dependent gene expression during tumor progression.

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