Citations

Abstract SETD2 is frequently mutated or deleted in clear cell renal cell carcinoma (ccRCC). Loss of SETD2 could create synthetic lethal dependencies that confer therapeutic vulnerabilities. In this study, we demonstrated that SETD2 deficiency promotes cytoplasmic mitochondrial DNA (mtDNA) leakage, leading to basal activation of cGAS-STING inflammatory signaling and increased apoptotic priming. This inflammatory state upregulated the BH3-only protein NOXA, constrained myeloid cell leukemia 1 (MCL-1) function, and enforced a synthetic lethal dependency on the antiapoptotic protein BCL-xL. Pharmacologic inhibition of BCL-xL further amplified cGAS-STING signaling in SETD2-deficient cells through sublethal mitochondrial outer membrane permeabilization, resulting in increased mtDNA release and robust NOXA induction. Elevated NOXA neutralized the compensatory MCL-1–mediated survival signaling, triggering apoptosis. In contrast, SETD2-proficient ccRCC cells exhibited minimal cGAS-STING activation and failed to induce NOXA following BCL-xL inhibition, rendering them resistant. Genetic ablation of cGAS, STING, IRF3, or NOXA rescued sensitivity to BCL-xL inhibition, confirming that mtDNA-driven innate immune signaling is required for this dependency. In vivo, BCL-xL inhibition suppressed tumor growth and prolonged survival in SETD2-deficient xenograft models. Collectively, these findings establish a mechanistic link between SETD2 loss, mtDNA-driven innate immune activation, and enforced BCL-xL dependence in ccRCC, revealing a therapeutically targetable vulnerability in SETD2-deficient tumors. Significance: SETD2 deficiency, which is associated with worse prognosis in kidney cancer, promotes mitochondrial DNA-driven cGAS-STING signaling and NOXA-mediated apoptotic priming, creating a therapeutically targetable dependency on BCL-xL in kidney cancer.

ABSTRACT We disclose an efficient transformation of the relatively common pyrroloiminoquinone discorhabdin alkaloids from Alaskan Latrunculia spp. to the complex ring system of aleutianamine by an acid catalyzed process that mimics the proposed endogenous genesis from 3‐dihydrodienyl discorhabdin precursors. The azepine ring system is formed by a concerted 1,2‐alkyl shift of a proposed thiocarbenium‐iminium dication and this mechanism is supported by extensive density functional theory (DFT) analysis. Additional in vitro biological data further supports the aleutianamines as novel and highly potent inhibitors of multidrug resistant cancer lines exemplified further with cytotoxicity toward chemotherapy resistant chromophobe renal cell carcinoma (IC 50 = 130 nM). This report provides a key transformation that allows the incorporation of either synthetic or biosynthetic starting materials leading to the generation of the aleutianamine complex ring system in just a single step from the discorhabdin ring system.

ABSTRACT We disclose an efficient transformation of the relatively common pyrroloiminoquinone discorhabdin alkaloids from Alaskan Latrunculia spp. to the complex ring system of aleutianamine by an acid catalyzed process that mimics the proposed endogenous genesis from 3‐dihydrodienyl discorhabdin precursors. The azepine ring system is formed by a concerted 1,2‐alkyl shift of a proposed thiocarbenium‐iminium dication and this mechanism is supported by extensive density functional theory (DFT) analysis. Additional in vitro biological data further supports the aleutianamines as novel and highly potent inhibitors of multidrug resistant cancer lines exemplified further with cytotoxicity toward chemotherapy resistant chromophobe renal cell carcinoma (IC 50 = 130 nM). This report provides a key transformation that allows the incorporation of either synthetic or biosynthetic starting materials leading to the generation of the aleutianamine complex ring system in just a single step from the discorhabdin ring system.

Germline variants in the NSD1 gene are responsible for Sotos syndrome, while somatic variants promote neoplastic cell transformation. Our previous studies revealed three alternative RNA isoforms of NSD1 present in fibroblast cell lines (FBs): the canonical full transcript and 2 alternative transcripts, termed AT2 (NSD1 Δ5Δ7) and AT3 (NSD1 Δ19–23 at the 5′ end). The precise molecular pathways affected by each specific isoform of NSD1 are uncharacterized to date. To elucidate the role of these isoforms, their expression was suppressed by siRNA knockdown in FBs and protein expression and transcriptome data was explored. We demonstrate that one gene target of NSD1 isoform AT2 is ARP3 actin-related protein 3 homolog B (ACTR3B). We show that loss of both canonical NSD1 and AT2 isoforms impaired the ability of fibroblasts to regulate the actin cytoskeleton, and we observed that this caused selective loss of stress fibers. Our findings provide novel insights into NSD1 function by distinguishing isoform function and demonstrating an essential role of NSD1 in regulating the actin cytoskeleton and stress fiber formation in fibroblasts.

Background and Aims: Disruption of the epigenome is a hallmark of human disease, including liver cirrhosis and HCC. While genetic heterogeneity is an established effector of pathologic phenotypes, epigenetic heterogeneity is less well understood. Environmental exposures alter the liver-specific DNA methylation landscape and influence the onset of liver cancer. Given that currently available treatments are unable to target frequently mutated genes in HCC, there is an unmet need for novel therapeutics to prevent or reverse liver damage leading to hepatic tumorigenesis, which the epigenome may provide. Approach and Results: We performed genome-wide profiling of DNA methylation, copy number, and gene expression from multiple liver regions from 31 patients with liver disease to examine their crosstalk and define the individual and combinatorial contributions of these processes to liver disease progression. We identified epigenetic heterogeneity hotspots that are conserved across patients. Elevated epigenetic heterogeneity is associated with increased gene expression heterogeneity. Cirrhotic regions comprise 2 distinct cohorts—one exclusively epigenetic, and the other where epigenetic and copy number variations collaborate. Epigenetic heterogeneity hotspots are enriched for genes central to liver function (eg, HNF1A) and known tumor suppressors (eg, RASSF1A). These hotspots encompass genes including ACSL1, ACSL5, MAT1A, and ELFN1, which have phenotypic effects in functional screens, supporting their relevance to hepatocarcinogenesis. Moreover, epigenetic heterogeneity hotspots are linked to clinical measures of outcome. Conclusions: Substantial epigenetic heterogeneity arises early in liver disease development, targeting key pathways in the progression and initiation of both cirrhosis and HCC. Integration of epigenetic and transcriptional heterogeneity unveils putative epigenetic regulators of hepatocarcinogenesis.

Abstract Clear cell renal carcinoma (ccRCC), which arises from the epithelial cells of the proximal tubule represents 70% of all renal cell carcinoma. Mutations that drive ccRCC in conjunction with near ubiquitous and early VHL loss include, PBRM1 (33 - 45%), BAP1 (15%) and SETD2 (13%). Loss of SETD2 leads to diminished occupancy of H3K36me3 in active gene bodies, which is progressively deregulated in primary RCC and metastasis, linking loss of H3K36me to tumor progression and metastasis. N6-Methyladenosine (m6A) is an important post-transcriptional regulator of RNA transcript stability and half-life. Preliminary findings have shown H3K36me3 (deposited by SETD2), targeting the core m6A methyltransferase machinery (METTL3, METTL14 and WTAP) to the mRNA by virtue of its interaction to METTL14 subunit. The goal of this study is to investigate if H3K36me3 depletion as observed in SETD2 mutant ccRCC, leads to a deregulated m6A methylome. We further investigate how deregulated methylome in key pathways leads to cancer initiation and progression in ccRCC. To accomplish our goals, we generated isogenic ccRCC cell lines with H3K36me3 depletion by knocking out SETD2. RNA-immunoprecipitation and sequencing for m6A (MeRIP) showed global deregulation of m6A methylome in SETD2KO isogenic ccRCC cell lines. We also show a number of pro-tumorigenic genes and pathways including cell invasion, inflammation and stemness being differentially methylated and expressed in SETD2KO ccRCC cell lines. Furthermore, we show SETD2KO cells being more sensitive to METTL3 inhibition suggesting the relevance of m6A hypermethylated transcripts in promoting pro-tumorigenic and growth promoting processes in SETD2KO ccRCC cell lines. Citation Format: Shafiq Shaikh, Ryan Wagner, Ryan Hlady, Keith D. Robertson. Perturbed RNA N6-methyladenosine methylome in SETD2 mutant clear cell renal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7074.

Histone‐lysine N‐methyltransferase SETD2 (SETD2), the sole histone methyltransferase that catalyzes trimethylation of lysine 36 on histone H3 (H3K36me3), is often mutated in clear cell renal cell carcinoma (ccRCC). SETD2 mutation and/or loss of H3K36me3 is linked to metastasis and poor outcome in ccRCC patients. Epithelial‐to‐mesenchymal transition (EMT) is a major pathway that drives invasion and metastasis in various cancer types. Here, using novel kidney epithelial cell lines isogenic for SETD2, we discovered that SETD2 inactivation drives EMT and promotes migration, invasion, and stemness in a transforming growth factor‐beta‐independent manner. This newly identified EMT program is triggered in part through secreted factors, including cytokines and growth factors, and through transcriptional reprogramming. RNA‐seq and assay for transposase‐accessible chromatin sequencing uncovered key transcription factors upregulated upon SETD2 loss, including SOX2, POU2F2 (OCT2), and PRRX1, that could individually drive EMT and stemness phenotypes in SETD2 wild‐type (WT) cells. Public expression data from SETD2 WT/mutant ccRCC support the EMT transcriptional signatures derived from cell line models. In summary, our studies reveal that SETD2 is a key regulator of EMT phenotypes through cell‐intrinsic and cell‐extrinsic mechanisms that help explain the association between SETD2 loss and ccRCC metastasis.