UTX and MLL4 Coordinately Regulate Transcriptional Programs for Cell Proliferation and Invasiveness in Breast Cancer Cells

Abstract

Histone methyltransferases and demethylases reversibly modulate histone lysine methylation, which is considered a key epigenetic mark associated with gene regulation. Recently, aberrant regulation of gene expression by histone methylation modifiers has emerged as an important mechanism for tumorigenesis. However, it remains largely unknown how histone methyltransferases and demethylases co-regulate transcriptional profiles for cancer cell characteristics. Here, we show that in breast cancer cells, the histone H3 lysine 27 (H3K27) demethylase UTX (also known as KDM6A) positively regulates gene expression programs associated with cell proliferation and invasion. The majority of UTX-controlled genes, including a cohort of oncogenes and pro-metastatic genes, are co-regulated by the H3K4 methyltransferase mixed lineage leukemia 4 (MLL4, also called ALR, KMT2D, and MLL2). UTX interacted with a C-terminal region of MLL4. UTX knockdown resulted in significant decreases in the proliferation and invasiveness of breast cancer cells in vitro and in a mouse xenograft model. Such defective cellular characteristics of UTX-depleted cells were phenocopied by MLL4 knockdown cells. UTX-catalyzed demethylation of trimethylated H3K27 and MLL4-mediated trimethylation at H3K4 occurred inter-dependently at co-target genes of UTX and MLL4. Clinically, high levels of UTX or MLL4 were associated with poor prognosis in breast cancer patients. Taken together, these findings uncover that coordinated regulation of gene expression programs by a histone methyltransferase and a histone demethylase is coupled to the proliferation and invasion of breast cancer cells.

Histone Methyltransferase hSETD1A Is a Novel Regulator of Metastasis in Breast Cancer

“…H3K4me3 is enriched at the TSS of transcriptionally active genes (16)(17)(18)(19), although whether this modification is a passive mark for active transcription or plays an active role in promoting transcription is currently under debate. Nevertheless, our group and others have observed both global and local changes in H3K4me3 at promoters of genes with cancer-promoting activity, in cancer cells (14,25,26,53,54). Methylation of H3K4 is primarily catalyzed by TrxG members, with the modification of H3K4me3 chiefly catalyzed by hSETD1A (26,27,(55)(56)(57)(58).…”

“…5B). While we are unsure how global levels of H3K4me3 are maintained following hSETD1A knockdown in breast cancer, the contribution of other TrxG family member(s), such as hSETD1B and MLL1-5, to the maintenance of H3K4me3 in breast cancer cells could be significant (14,27,64). In support of this possibility, we observed a significant increase in the transcript levels of hSETD1B in primary and metastatic breast cancer samples ( Supplementary Fig.…”

“…Several histone-modifying enzymes have been linked to breast tumorigenesis including Ezh2 H3K27 methyltransferase (9-11), LSD1 H3K4 demethylase (12), HDAC6 histone deacetylase (13), UTX H3K27 demethylase (14), and JMJD2C H3K9/H3K36 demethylase (15). While such enzymes are promising targets for therapeutic intervention, a more thorough understanding of their impact on tumor phenotype is required.…”

“…Levels of H3K4me3 are globally and locally altered during different developmental stages of cancer, and can serve as a predictor for disease recurrence (20)(21)(22)(23)(24)(25)(26). It was also recently determined that increased H3K4me3 and decreased H3K27me3 is important for activation of genes linked to proliferation and invasion of breast cancer such as matrix metalloproteinases (MMP), ERBB3, Six1, Cyclin A1, Pim-1, and CSPG4 (14).…”

Transposon mutagenesis identifies genes and cellular processes driving epithelial-mesenchymal transition in hepatocellular carcinoma

“…In contrast, Thieme et al (58) showed that Kdm6a positively regulates the migration of hematopoietic stem cells. In addition, Kim et al (60) reported that knockdown of KDM6A decreased the migration and invasion capacity of breast cancer cell lines.…”