HOXC10 is overexpressed in breast cancer and transcriptionally regulated by estrogen via involvement of histone methylases MLL3 and MLL4

Abstract

HOXC10 is a critical player in the development of spinal cord, formation of neurons, and associated with human leukemia. We found that HOXC10 is overexpressed in breast cancer and transcriptionally regulated by estrogen (17b-estradiol, E 2 ). The HOXC10 promoter contains several estrogen response elements (ERE1-7, half-sites). A luciferase-based reporter assay showed that ERE1 and ERE6 of HOXC10 promoter are E 2 responsive. ERa and ERb play critical roles in E 2 -mediated activation of HOXC10. Knockdown of ERa and ERb downregulated E 2 -induced HOXC10 expression. ERa and ERb bind to ERE1 and ERE6 regions in an E 2 -dependent manner. Additionally, knockdown of histone methylases MLL3 and MLL4 (but not MLL1 and MLL2) diminished E 2 -induced expression of HOXC10. MLL3 and MLL4 were bound to the ERE1 and ERE6 regions of HOXC10 promoter in an E 2 -dependent manner. Overall, we demonstrated that HOXC10 is overexpressed in breast cancer, and it is an E 2 -responsive gene. Histone methylases MLL3 and MLL4, along with ERs, regulate HOXC10 gene expression in the presence of E 2 .

Bisphenol-A induces expression of HOXC6, an estrogen-regulated homeobox-containing gene associated with breast cancer

“…Cells were grown to 60 % confluency and then treated with E2 or BPA. RNA and proteins were isolated and analyzed by real-time PCR (qPCR) and western blotting, respectively (14, 16, 41, 45–47). …”

“…The tissue microarray slides were dehydrated with sequential immersion in 70%, 95%, and 100% ethanol and then cleaned by sequential incubation (1, 5 and 10 min) in CitriSolv clearing agent (Fisherband). Tissue sections were finally mounted with DPX mounting solution (Sigma), photographed, and examined under microscope (Nikon Eclipse TE2000-U, Japan) (14). …”

“…Control transfections were done using empty pGL3 promoter vector without any ERE insertion. At 30 h post-transfection, cells were treated with 1 nM E2 or 10 nM BPA and incubated for an additional 8 h. Total protein was extracted and then subjected to luciferase assay using Dual-Glo Luciferase Assay System (Promega) as instructed and detected using a microplate reader (Flowstar-Omega) (14, 15, 41, 44, 48–50). Each treatment was done in four replicates and the experiment was repeated at least twice.…”

HOXC10 suppresses browning of white adipose tissues

“…10 It has been shown to be involved in breast cancer, thyroid cancer and cervical squamous cell growth. [11][12][13][14] A genome-wide association study indicates that HOXC10 could also be associated with increased waist-to-hip ratio in humans. 15 Here we identify that HOXC10 is enriched in inguinal (SubQ) WAT and is a key negative regulator in the process of browning SubQ WAT alone, with no discerning effect on classical BAT function.…”

Development and Use of Assay Conditions Suited to Screening for and Profiling of SET-Domain-Targeted Inhibitors of the MLL/SET1 Family of Lysine Methyltransferases

“…Furthermore, knockdown of MLLs3 and 4 diminishes estrogen-induced expression of HOXC10, which is overexpressed in breast cancer. 38 The WRAD 2 subunit WDR5 is critical for assembly of the full MLL/SET1 core complexes, and interactions between the MLL/SET1 subunits and WDR5 are mediated by the Win motif (WDR5 interaction motif), a six-residue sequence located just N-terminal to the overall C-terminal location of the SET domains in this family. 27,39 The last four residues of the Win motif (AR-S/A-E) have homology to the four N-terminal residues of histone H3 (ARTK) and, for two of the family members, MLL1 and MLL4, this homology extends beyond the Win motif to include downstream residues identical or similar to H3 residues 8-10 (RKS).…”