ABSTRACT
WBP2 transcription coactivator is an emerging oncoprotein and a key node of convergence between EGF and Wnt signaling pathways. Understanding how WBP2 is regulated has important implications for cancer therapy. WBP2 is tightly controlled by post-translational modifications, including phosphorylation and ubiquitination, leading to changes in subcellular localization, protein-protein interactions, and protein turnover. As the function of WBP2 is intricately linked to YAP and TAZ, we hypothesize that WBP2 is negatively regulated by the Hippo tumor suppressor pathway. Indeed, MST is demonstrated to negatively regulate WBP2 expression in a kinase-dependent but LATS-independent manner. This was observed in the majority of the breast cancer cell lines tested. The effect of MST was enhanced by SAV and concomitant with the inhibition of the transcription co-activation, in vitro and in vivo tumorigenesis activities of WBP2, resulting in good prognosis in xenografts. Downregulation of WBP2 by MST involved miRNA but not proteasomal or lysosomal degradation. Our data support the existence of a novel MST-Dicer signaling axis, which in turn regulates both WBP2 CDS- and UTR-targeting miRNAs expression, including miR-23a. MiR-23a targets the 3'UTR of WBP2 mRNA directly. Significant inverse relationships between WBP2 and MST or miR23a expression levels in clinical specimens were observed. In conclusion, WBP2 is a target of the Hippo/MST kinase; MST is identified as yet another rheostat in the regulation of WBP2 and its oncogenic function. The findings have implications in targeted therapeutics and precision medicine for breast cancer.
Subject(s)
Breast Neoplasms/metabolism , DEAD-box RNA Helicases/metabolism , Ribonuclease III/metabolism , Trans-Activators/metabolism , Adaptor Proteins, Signal Transducing/genetics , Cell Line, Tumor , DEAD-box RNA Helicases/genetics , Gene Expression/genetics , Gene Expression Regulation, Neoplastic/genetics , Hippo Signaling Pathway , Humans , MAP Kinase Kinase Kinases/metabolism , MAP Kinase Kinase Kinases/physiology , MCF-7 Cells , MicroRNAs/genetics , MicroRNAs/metabolism , Oncogene Proteins/genetics , Phosphorylation , Protein Serine-Threonine Kinases/metabolism , Protein Serine-Threonine Kinases/physiology , Ribonuclease III/genetics , Signal Transduction/genetics , Trans-Activators/physiology , Transcription Factors/metabolism , Wnt Signaling PathwayABSTRACT
BACKGROUND: Transcription factors are commonly deregulated in various cancers. Here, we evaluated role of ELF3 in pathogenesis of bladder carcinoma (BCa). MATERIALS AND METHODS: We confirmed ELF3 expression pattern in BCa cell lines using western blot; and in different grades of tumors using Immunohistochemistry. Cell invasion assay was employed to demonstrate potential role of ELF3 in EMT. RESULTS AND CONCLUSION: ELF3 showed selective expression in low-grade cell lines and tumor tissues. Overexpression of ELF3 in mesenchymal cell line UMUC3 resulted in reduced invasion and decreased expression of mesenchymal markers. We observed association of low ELF3 expression with increased risk and overall poor survival using publicly available data. ELF3-modulated reversal of EMT might be a useful strategy in the treatment of bladder cancer.
Subject(s)
DNA-Binding Proteins/genetics , Epithelial-Mesenchymal Transition/genetics , Gene Expression Regulation, Neoplastic , Proto-Oncogene Proteins c-ets/genetics , Transcription Factors/genetics , Urinary Bladder Neoplasms/etiology , Urinary Bladder Neoplasms/pathology , Biomarkers, Tumor , Cell Line, Tumor , Cell Movement , Cell Proliferation , Computational Biology/methods , DNA-Binding Proteins/metabolism , Gene Expression Profiling , Humans , Immunohistochemistry , Multigene Family , Neoplasm Grading , Neoplasm Staging , Prognosis , Proto-Oncogene Proteins c-ets/metabolism , Transcription Factors/metabolism , Transcriptome , Urinary Bladder Neoplasms/metabolism , Urinary Bladder Neoplasms/mortalityABSTRACT
The repression of telomerase activity during cellular differentiation promotes replicative aging and functions as a physiological barrier for tumorigenesis in long-lived mammals, including humans. However, the underlying mechanisms remain largely unclear. Here we describe how miR-615-3p represses hTERT expression. mir-615-3p is located in an intron of the HOXC5 gene, a member of the highly conserved homeobox family of transcription factors controlling embryogenesis and development. Unexpectedly, we found that HoxC5 also represses hTERT expression by disrupting the long-range interaction between hTERT promoter and its distal enhancer. The 3'UTR of hTERT and its upstream enhancer region are well conserved in long-lived primates. Both mir-615-3p and HOXC5 are activated upon differentiation, which constitute a feed-forward loop that coordinates transcriptional and post-transcriptional repression of hTERT during cellular differentiation. Deregulation of HOXC5 and mir-615-3p expression may contribute to the activation of hTERT in human cancers.
