Project description:Tumors with mutations in chromatin regulators present attractive targets for DNA hypomethylating agent 5-aza-2'-deoxycytidine (DAC) therapy, which further disrupts cancer cells' epigenomic fidelity and reactivates transposable element (TE) expression to drive viral mimicry responses. SETD2 encodes a histone methyltransferase (H3K36me3) and is prevalently mutated in advanced kidney cancers. Here, we show that SETD2-mutant kidney cancer cells are especially sensitive in vitro and in vivo to DAC treatment. We find that the viral mimicry response are direct consequences of mis-splicing events, such as exon inclusions or extensions, triggered by DAC treatment in an SETD2-loss context. Comprehensive epigenomic analysis reveals H3K9me3 deposition, rather than DNA methylation dynamics, across intronic TEs might contribute to elevated mis-splicing rates. Through epigenomic and transcriptomic analyses, we show that SETD2-deficient kidney cancers are prone to mis-splicing, which can be therapeutically exacerbated with DAC treatment to increase viral mimicry activation and provide synergy with combinatorial immunotherapy approaches.
Project description:The dysregulation of the histone H3 lysine 36 (H3K36) methyltransferase, SETD2, is associated with worse clinical outcomes and metastasis in clear cell Renal Cell Carcinoma (ccRCC). Here, we reveal that kidney cancer cells displaying diminished H3K36me3 levels (SETD2 deficiency) show increased sensitivity to the anti-tumor effects of the DNA hypomethylating agent 5-aza-2’-deoxycytidine (Decitabine/DAC). DAC treatment induced stronger viral mimicry activation and immunostimulatory signals by higher transposable element (TE) expression in SETD2-mutant cancer cells. Surprisingly, we demonstrate that the increased TE abundance in SETD2-knockout (SETD2-KO) kidney cancer cells is substantially derived from mis-spliced products induced by DAC treatment. Epigenetic profiling suggests that differential DNA methylation, H3K36me3, and H3K9me3 marks across exons and intronic TEs might contribute to elevated mis-splicing rates specifically in the SETD2 loss context. Finally, SETD2 dysregulation also sensitized tumors in vivo to combinatorial therapy of DAC and immune checkpoint inhibitors highlighting the translational potential for this precision medicine.
Project description:The dysregulation of the histone H3 lysine 36 (H3K36) methyltransferase, SETD2, is associated with worse clinical outcomes and metastasis in clear cell Renal Cell Carcinoma (ccRCC). Here, we reveal that kidney cancer cells displaying diminished H3K36me3 levels (SETD2 deficiency) show increased sensitivity to the anti-tumor effects of the DNA hypomethylating agent 5-aza-2’-deoxycytidine (Decitabine/DAC). DAC treatment induced stronger viral mimicry activation and immunostimulatory signals by higher transposable element (TE) expression in SETD2-mutant cancer cells. Surprisingly, we demonstrate that the increased TE abundance in SETD2-knockout (SETD2-KO) kidney cancer cells is substantially derived from mis-spliced products induced by DAC treatment. Epigenetic profiling suggests that differential DNA methylation, H3K36me3, and H3K9me3 marks across exons and intronic TEs might contribute to elevated mis-splicing rates specifically in the SETD2 loss context. Finally, SETD2 dysregulation also sensitized tumors in vivo to combinatorial therapy of DAC and immune checkpoint inhibitors highlighting the translational potential for this precision medicine.
Project description:Large-scale sequencing efforts in Clear cell renal cell carcinoma (ccRCC) have found a high prevalence of mutations in chromatin-related genes. Prominent within this group is SETD2, which is mutated in 15% of ccRCC and is associated with aggressive disease. SETD2 is a methyltransferase responsible for trimethylating lysine 36 on histone H3 (H3K36me3). Although it is not completely understood how SETD2 loss contributes to ccRCC tumorigenesis, it is thought that it reprograms the epigenetic landscape of the cell. Here we explore the impact that SETD2/H3K36me3 loss has on the DNA methylome in ccRCC cells. DNA methylation was measured using the EPIC DNA methylation assay in 786-O ccRCC cells and non-cancerous transformed proximal tubule kidney cells (HKC) with and without SETD2. Sensitivity to DNA hypomethylating agents was assessed by dose-response assay using 5-aza-2'-deoxycytidine. Apoptosis was measured via Annexin-V/PI staining by flow cytometry. Mitochondrial fitness was evaluated by electron microscopy and flow cytometry. Moreover, activity of 5-aza-2'-deoxycytidine, a DNA hypomethylating agent, in was assessed in SETD2 WT/KO xenografts in NOD-Scid mice. SETD2 loss resulted in DNA hypermethylation in HKC cells and to a greater extent in 786-O. Dose-response assays showed that SETD2-null ccRCC cells are sensitive to 5-aza-2'-deoxycytidine. Furthermore, Annexin-V/PI staining revealed more apoptotic and necrotic cells in SETD2-null cells following 5-aza-2'-deoxycytidine treatment, which was rescued using a Caspase inhibitor. In addition, 5-aza-2'-deoxycytidine induced profound changes in mitochondria in SETD2-null cells, including loss of membrane potential and size reduction. Indeed, in vivo experiments verified increased SETD2-null xenografts’ sensitivity to 5-aza-2'-deoxycytidine. We show that SETD2 loss in ccRCC cells causes DNA hypermethylation, creating a synthetic lethal dependency with DNA hypomethylating agents.
Project description:Splicing factor SF3B1 mutations are frequent somatic lesions in myeloid neoplasms that transform hematopoietic stem cells (HSCs) by inducing mis-splicing of target genes. However, the molecular and functional consequences of SF3B1 mutations in human HSCs and progenitors (HSPCs) remain unclear. Here, we identify the mis-splicing program in human HSPCs as a targetable vulnerability by precise gene editing of SF3B1 K700E mutations in primary CD34+ cells. Mutant SF3B1 induced pervasive mis-splicing and reduced expression of genes regulating mitosis and genome maintenance leading to altered differentiation, delayed G2/M progression, and profound sensitivity to CHK1 inhibition (CHK1i). Mis-splicing or reduced expression of mitotic regulators BUBR1 and CDC27 delayed G2/M transit and promoted CHK1i sensitivity. Clinical CHK1i prexasertib selectively targeted SF3B1-mutant immunophenotypic HSCs and abrogated engraftment in vivo. These findings identify mis-splicing of mitotic regulators in SF3B1-mutant HSPCs as a targetable vulnerability engaged by pharmacological CHK1 inhibition. Significance: In this study, we engineer precise SF3B1 mutations in human HSPCs and identify CHK1 inhibition as a selective vulnerability promoted by mis-splicing of mitotic regulators. These findings uncover the mis-splicing program induced by mutant SF3B1 in human HSPCs and show that it can be therapeutically targeted by clinical CHK1 inhibitors.
Project description:Genome-wide DNA methylation profiling of SETD2-null 786-0 RCC cells treated with decitabine (100nM and 300nM) or DMSO vehicle. The Illumina Infinium HumanMethylation EPIC BeadChip was used to obtain DNA methylation profiles across approximately 850K CpGs.