Nkx3.1 and Myc crossregulate shared target genes in mouse and human prostate tumorigenesis
Philip D. Anderson, … , Isam-Eldin Eltoum, Sarki A. Abdulkadir
Philip D. Anderson, … , Isam-Eldin Eltoum, Sarki A. Abdulkadir
Published April 9, 2012
Citation Information: J Clin Invest. 2012;122(5):1907-1919. https://doi.org/10.1172/JCI58540.
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Research Article Oncology

Nkx3.1 and Myc crossregulate shared target genes in mouse and human prostate tumorigenesis

Abstract

Cooperativity between oncogenic mutations is recognized as a fundamental feature of malignant transformation, and it may be mediated by synergistic regulation of the expression of pro- and antitumorigenic target genes. However, the mechanisms by which oncogenes and tumor suppressors coregulate downstream targets and pathways remain largely unknown. Here, we used ChIP coupled to massively parallel sequencing (ChIP-seq) and gene expression profiling in mouse prostates to identify direct targets of the tumor suppressor Nkx3.1. Further analysis indicated that a substantial fraction of Nkx3.1 target genes are also direct targets of the oncoprotein Myc. We also showed that Nkx3.1 and Myc bound to and crossregulated shared target genes in mouse and human prostate epithelial cells and that Nkx3.1 could oppose the transcriptional activity of Myc. Furthermore, loss of Nkx3.1 cooperated with concurrent overexpression of Myc to promote prostate cancer in transgenic mice. In human prostate cancer patients, dysregulation of shared NKX3.1/MYC target genes was associated with disease relapse. Our results indicate that NKX3.1 and MYC coregulate prostate tumorigenesis by converging on, and crossregulating, a common set of target genes. We propose that coregulation of target gene expression by oncogenic/tumor suppressor transcription factors may represent a general mechanism underlying the cooperativity of oncogenic mutations during tumorigenesis.

Authors

Philip D. Anderson, Sydika A. McKissic, Monica Logan, Meejeon Roh, Omar E. Franco, Jie Wang, Irina Doubinskaia, Riet van der Meer, Simon W. Hayward, Christine M. Eischen, Isam-Eldin Eltoum, Sarki A. Abdulkadir

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Figure 5

NKX3.1 and Myc interact and coregulate expression of shared target gene HK2.

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NKX3.1 and Myc interact and coregulate expression of shared target gene ...
(A) Myc and NKX3.1 coimmunoprecipitation. Cell lysates from 293T cells expressing HA-NKX3.1 and Flag-Myc were immunoprecipitated with the indicated antibodies and immunoblotted for HA. To deplete DNA, ethidium bromide (EtBr) was added to lysates for 30 minutes prior to immunoprecipitation and during washes. (B) Coimmunoprecipitation of HA-NKX3.1 and Flag-Myc WT (lane 2), Flag-Myc mutant 1 lacking Myc–box 1 (lane 3), or Flag-Myc mutant 2 lacking Myc–box 2 (lane 4) in 293 cells. Asterisk indicates a nonspecific band. (C) ChIP–re-ChIP assay. LNCaP cells were subjected to ChIP by NKX3.1 antibody followed by ChIP with Myc antibody or the reverse and binding interrogated at the HK2 promoter E box. (D) Depletion of NKX3.1 by siRNA in LNCaP cells leads to upregulation of HK2 expression compared with control siLuc (luciferase siRNA) treatment. (E) Depletion of NKX3.1 by siRNA in LNCaP-Myc ER cells enhances activation of HK2 gene expression by tamoxifen (OHT) compared with control siGFP treatment (left panel). In contrast, expression of exogenous Nkx3.1 inhibited OHT induction of Hk2 in DKO cells. Results are representative of at least 2 independent experiments. Error bars represent mean ± SEM. See also Supplemental Figure 4.