AML1/ETO trans‐activates c‐KIT expression through the long range interaction between promoter and intronic enhancer

Abstract

The AML1/ETO onco-fusion protein is crucial for the genesis of t(8;21) acute myeloid leukemia (AML) and is well documented as a transcriptional repressor through dominant-negative effect. However, little is known about the transactivation mechanism of AML1/ETO. Through large cohort of patient's expression level data analysis and a series of experimental validation, we report here that AML1/ETO transactivates c-KIT expression through directly binding to and mediating the long-range interaction between the promoter and intronic enhancer regions of c-KIT. Gene expression analyses verify that c-KIT expression is significantly high in t(8;21) AML. Further ChIP-seq analysis and motif scanning identify two regulatory regions located in the promoter and intronic enhancer region of c-KIT, respectively. Both regions are enriched by co-factors of AML1/ETO, such as AML1, CEBPe, c-Jun, and c-Fos. Further luciferase reporter assays show that AML1/ETO trans-activates c-KIT promoter activity through directly recognizing the AML1 motif and the co-existence of co-factors. The induction of c-KIT promoter activity is reinforced with the existence of intronic enhancer region. Furthermore, ChIP-3C-qPCR assays verify that AML1/ETO mediates the formation of DNA-looping between the c-KIT promoter and intronic enhancer region through the long-range interaction. Collectively, our data uncover a novel transcriptional activity mechanism of AML1/ETO and enrich our knowledge of the onco-fusion protein mediated transcription regulation.

The RUNX1–ETO fusion protein trans‐activates c‐KIT expression by recruiting histone acetyltransferase P300 on its promoter

“…RUNX1–ETO and RUNX1 were originally characterized as DNA binding proteins that recognize the conserved core sequence TGT/Cggt . A bioinformatics search (JASPAR, Searching Transcription Factor Binding Sites, http://jaspar.genereg.net/) revealed the presence of three putative RUNX1–ETO binding sites on the upstream region of the c‐KIT promoter (−2000 bp to 0 bp, Fig.…”

“…It has been reported that RUNX1–ETO increases c‐KIT promoter activity through directly binding to the promoter region via the RUNX1 motifs located at +655 and +674 relative to the TSS . However, RUNX1–ETO regulated downstream genes miR‐193a , DNMT3a , and SIRT1 by binding to the promoter region (−280 bp, −1890 to −1821 bp, and −546 bp realtive to the TSS) , and as is well known, promoter sequences are usually the sequence upstream of the TSS and play an important role for transcriptional regulation.…”

“…Moreover, 35.8–81.3% of the RUNX1–ETO positive (RE + ) AML patients have abnormally high c‐KIT expression, which is much higher than that of RUNX1–ETO negative (RE − ) AML patients . It has been demonstrated that RUNX1–ETO trans ‐activated c‐KIT activity through directly binding to the region via the RUNX1 motifs located in +655 and +674 bp relative to the transcription start site (TSS) . However, it is still unclear whether the upstream region of the c‐KIT promoter participates in c‐KIT transactivation and whether RUNX1–ETO regulates c‐KIT through the upstream region of the c‐KIT promoter.…”

Polyphyllin I Inhibits Proliferation and Induces Apoptosis by Downregulating AML1‐ETO and Suppressing C‐KIT/Akt Signaling in t(8;21) Acute Myeloid Leukemia

“…C-KIT is also a downstream target gene of AML1-ETO. [27] We also detected C-KIT expression and phosphorylation; PPI decreased the expression and phosphorylation of C-KIT. In addition, the phosphorylation of Akt, a downstream factor of the C-KIT signal pathway, was also downregulated by PPI ( Figure 5).…”

Interplay between transcription regulators RUNX1 and FUBP1 activates an enhancer of the oncogenec-KITand amplifies cell proliferation

“…Moreover, we identified two regulatory regions in the first intron of c-KIT (the +700 bp promoter and the +30 kb enhancer regions) that are bound by RUNX1, FUBP1 and present active histone marks. Interestingly, a very recent study in AML1-ETO acute myeloid leukemia spotted identical regulatory regions in c-KIT gene bound by RUNX1 (or AML1) and the fusion protein AML1-ETO ( 72 ). The role of the transcriptional regulators RUNX1 and FUBP1 in a potential interplay between c-KIT enhancer and promoter has not been addressed yet.…”