HIC1 interacts with and modulates the activity of STAT3.
HIC1 (hypermethylated in cancer 1) is a tumor suppressor gene, expression of which is frequently suppressed in human cancers. Very little is known about the molecular basis of HIC1 in antagonizing oncogenic pathways. Here, we report that HIC1 forms complexes with the signal transducers and activators of transcription 3 (STAT3) and attenuates STAT3-mediated transcription. STAT3 was identified as a HIC1-interacting protein by affinity capture and followed by mass spectrometry analysis. Overexpression or depletion of HIC1 resulted in decreased or increased levels of interleukin-6 (IL-6)/oncostatin M (OSM)-induced STAT3-mediated reporter activity and expression of target genes such as VEGF and c-Myc, respectively. Furthermore, HIC1 suppressing the VEGF and c-Myc promoter activity and the colony formation of MDA-MB 231 cells were STAT3-dependent. Further studies showed that HIC1 interacts with the DNA binding domain of STAT3 and suppresses the binding of STAT3 to its target gene promoters. Domain mapping study revealed that HIC1 C-terminal domain binds to STAT3. HIC1 mutant defective in STAT3 interaction reduced its repressive effect on STAT3 DNA binding activity, the reporter activity and gene expression of the VEGF and c-Myc genes, and cell growth in MDA-MB 231 cells. Altogether, our findings not only provide a novel role of HIC1 in antagonizing STAT3-mediated activation of VEGF and c-Myc gene expression and cell growth, but also elucidate a molecular basis underlying the inhibitory effect of HIC1 on STAT3 transcriptional potential.
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, ROC.
Ying-Mei
YM
Lin
Chia-Mei
CM
Wang
Jen-Chong
JC
Jeng
Dominique
D
Leprince
Hsiu-Ming
HM
Shih
D000595:Amino Acid Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors / Q000235:genetics* / Q000378:metabolism; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D053683:Oncostatin M / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics* / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism
C499808:HIC1 protein, human; C508600:IL6 protein, human; D015850:Interleukin-6; D051741:Kruppel-Like Transcription Factors; C489427:MYC protein, human; C508351:OSM protein, human; D016271:Proto-Oncogene Proteins c-myc; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D053683:Oncostatin M; D008156:Luciferases
DNA binding; HIC1; STAT3; protein interaction; transcriptional regulation