Regulation of miRNA Biogenesis and Histone Modification by K63-Polyubiquitinated DDX17 Controls Cancer Stem-like Features

Abstract

Markers of cancer stemness predispose patients to tumor aggressiveness, drug and immunotherapy resistance, relapse, and metastasis. DDX17 is a cofactor of the Drosha-DGCR8 complex in miRNA biogenesis and transcriptional coactivator and has been associated with cancer stem-like properties. However, the precise mechanism by which DDX17 controls cancer stem-like features remains elusive. Here, we show that the E3 ligase HectH9 mediated K63-polyubiquitination of DDX17 under hypoxia to control stem-like properties and tumor-initiating capabilities. Polyubiquitinated DDX17 disassociated from the Drosha-DGCR8 complex, leading to decreased biogenesis of anti-stemness miRNAs. Increased association of polyubiquitinated DDX17 with p300-YAP resulted in histone 3 lysine 56 (H3K56) acetylation proximal to stemness-related genes and their subsequent transcriptional activation. High expression of HectH9 and six stemnessrelated genes (BMI1, SOX2, OCT4, NANOG, NOTCH1, and NOTCH2) predicted poor survival in patients with head and neck squamous cell carcinoma and lung adenocarcinoma. Our findings demonstrate that concerted regulation of miRNA biogenesis and histone modifications through posttranslational modification of DDX17 underlies many cancer stemlike features. Inhibition of DDX17 ubiquitination may serve as a new therapeutic venue for cancer treatment. Significance: Hypoxia-induced polyubiquitination of DDX17 controls its dissociation from the pri-miRNA-Drosha-DCGR8 complex to reduce anti-stemness miRNA biogenesis and association with YAP and p300 to enhance transcription of stemness-related genes.

RNA Specificity and Autoregulation of DDX17, a Modulator of MicroRNA Biogenesis

“…The role of DDX17 as an enhancer of pri-miR processing has been established in various cellular contexts (Kao et al, 2019;Mori et al, 2014;Remenyi et al, 2016). Using a reconstituted system, we provide a mechanistic model for how DDX17 enhances the maturation of certain miRs.…”

“…DEADbox proteins are necessary for proper function of RNA in many cellular processes (Cordin et al, 2006;Fuller-Pace, 2013b;Gustafson and Wessel, 2010;Janknecht, 2010;Jarmoskaite and Russell, 2011). DDX17 and its close homolog DDX5 play an important role in various contexts, including processing of primary microRNA transcripts (pri-miRs) in the nucleus (Kao et al, 2019;Li et al, 2017;Mori et al, 2014), pre-mRNA alternative splicing Hö nig et al, 2002), ribosome biogenesis (Jalal et al, 2007), mRNA export (Montpetit et al, 2011), and coregulation of transcription Fuller-Pace, 2013a;Lambert et al, 2018;Samaan et al, 2014). DDX17 has also been implicated in immunity by affecting viral infectivity (Lorgeoux et al, 2013;Moy et al, 2014;Sithole et al, 2018).…”

miRNA-based biomarkers, therapies, and resistance in Cancer

“…Regulatory post-translational modifications (PTMs), like the phosphorylation, ubiquitylation, and sumoylation of miRNA biogenesis factors, can also affect miRNA processing by connecting miRNA expression with cell signaling pathways [23]. For example, a newly published study indicated that through the PTM of DDX17 (a cofactor of the Drosha-DGCR8 complex), miRNA biogenesis and histone modifications can get concerted regulation, which underlies many cancer stem-like features [33]. The target messenger RNA (mRNA) can also regulate the biogenesis of cognate miRNAs [34].…”

Histone modifications in oral squamous cell carcinoma and oral potentially malignant disorders

“…ERK1/2 phosphorylation suppressed by melatonin reduced p300/CBP level, decreased histone acetylation, then dampened matrix metalloproteinase‐9 transcription, and decreased cell migration (Yeh et al, ). Polyubiquitinated‐p72 RNA helicase and transcriptional coactivator DDX17, ubiquitin‐binding protein p300, and Yes‐associated protein increased H3K56ac occupancy on the promoters of stemness‐related genes under hypoxia (Kao et al, ). Transcriptional regulator TIP60, a MYST domain HAT which modulates DNA double‐strand break (DSB) repair, was reduced in primary HNSCC (Gorrini et al, ).…”

“…In HNSCC, strong BMI1 and tumor‐suppressor CDKN2A/p16 absence was associated with poor DFS and recurrence‐free survival (Huber et al, ) and higher BMI1 was associated with metastasis (Chen et al, ). Co‐expression of ubiquitin E3 ligase HectH9 and stemness‐related genes (BMI1, NANOG, NOTCH1/2, OCT4, and SOX2) predicted poor clinical outcome in patients with HNSCC (Kao et al, ). BMI1 + CSCs were required for 4‐NQO‐induced OSCC invasive progression and metastasis (Chen et al, ).…”