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The Journal of Clinical Investigation Nov 2022Mutational activation of KRAS is a common oncogenic event in lung cancer, yet effective therapies are still lacking. Here, we identify B cell lymphoma 6 (BCL6) as a...
Mutational activation of KRAS is a common oncogenic event in lung cancer, yet effective therapies are still lacking. Here, we identify B cell lymphoma 6 (BCL6) as a lynchpin in KRAS-driven lung cancer. BCL6 expression was increased upon KRAS activation in lung tumor tissue in mice and was positively correlated with the expression of KRAS-GTP, the active form of KRAS, in various human cancer cell lines. Moreover, BCL6 was highly expressed in human KRAS-mutant lung adenocarcinomas and was associated with poor patient survival. Mechanistically, the MAPK/ERK/ELK1 signaling axis downstream of mutant KRAS directly regulated BCL6 expression. BCL6 maintained the global expression of prereplication complex components; therefore, BCL6 inhibition induced stalling of the replication fork, leading to DNA damage and growth arrest in KRAS-mutant lung cancer cells. Importantly, BCL6-specific knockout in lungs significantly reduced the tumor burden and mortality in the LSL-KrasG12D/+ lung cancer mouse model. Likewise, pharmacological inhibition of BCL6 significantly impeded the growth of KRAS-mutant lung cancer cells both in vitro and in vivo. In summary, our findings reveal a crucial role of BCL6 in promoting KRAS-addicted lung cancer and suggest BCL6 as a therapeutic target for the treatment of this intractable disease.
Topics: Humans; Mice; Animals; Proto-Oncogene Proteins p21(ras); Lung Neoplasms; Adenocarcinoma of Lung; Mutation; Disease Models, Animal; Cell Line, Tumor; Proto-Oncogene Proteins c-bcl-6; ets-Domain Protein Elk-1
PubMed: 36377663
DOI: 10.1172/JCI161308 -
Science Advances Feb 2021Most intracellular proteins lack hydrophobic pockets suitable for altering their function with drug-like small molecules. Recent studies indicate that some undruggable...
Most intracellular proteins lack hydrophobic pockets suitable for altering their function with drug-like small molecules. Recent studies indicate that some undruggable proteins can be targeted by compounds that can degrade them. For example, thalidomide-like drugs (IMiDs) degrade the critical multiple myeloma transcription factors IKZF1 and IKZF3 by recruiting them to the cereblon E3 ubiquitin ligase. Current loss of signal ("down") assays for identifying degraders often exhibit poor signal-to-noise ratios, narrow dynamic ranges, and false positives from compounds that nonspecifically suppress transcription or translation. Here, we describe a gain of signal ("up") assay for degraders. In arrayed chemical screens, we identified novel IMiD-like IKZF1 degraders and Spautin-1, which, unlike the IMiDs, degrades IKZF1 in a cereblon-independent manner. In a pooled CRISPR-Cas9-based screen, we found that CDK2 regulates the abundance of the ASCL1 oncogenic transcription factor. This methodology should facilitate the identification of drugs that directly or indirectly degrade undruggable proteins.
Topics: Adaptor Proteins, Signal Transducing; Basic Helix-Loop-Helix Transcription Factors; Benzylamines; CRISPR-Cas Systems; Humans; Ikaros Transcription Factor; Oncogene Proteins; Proteolysis; Quinazolines; Thalidomide; Transcription Factors
PubMed: 33547076
DOI: 10.1126/sciadv.abd6263 -
Cancer Cell Sep 2022Immunotargeting of tumor-specific antigens is a powerful therapeutic strategy. Immunotherapies directed at MHC-I complexes have expanded the scope of antigens and...
Immunotargeting of tumor-specific antigens is a powerful therapeutic strategy. Immunotherapies directed at MHC-I complexes have expanded the scope of antigens and enabled the direct targeting of intracellular oncoproteins at the cell surface. We asked whether covalent drugs that alkylate mutated residues on oncoproteins could act as haptens to generate unique MHC-I-restricted neoantigens. Here, we report that KRAS G12C mutant cells treated with the covalent inhibitor ARS1620 present ARS1620-modified peptides in MHC-I complexes. Using ARS1620-specific antibodies identified by phage display, we show that these haptenated MHC-I complexes can serve as tumor-specific neoantigens and that a bispecific T cell engager construct based on a hapten-specific antibody elicits a cytotoxic T cell response against KRAS G12C cells, including those resistant to direct KRAS G12C inhibition. With multiple K-RAS G12C inhibitors in clinical use or undergoing clinical trials, our results present a strategy to enhance their efficacy and overcome the rapidly arising tumor resistance.
Topics: Antibodies; Antineoplastic Agents; Histocompatibility Antigens Class I; Humans; Immunologic Factors; Immunotherapy; Neoplasms; Peptides; Proto-Oncogene Proteins p21(ras)
PubMed: 36099883
DOI: 10.1016/j.ccell.2022.07.005 -
Nature Communications May 2022Oncoprotein SS18-SSX is a hallmark of synovial sarcomas. However, as a part of the SS18-SSX fusion protein, SS18's function remains unclear. Here, we depict the...
Oncoprotein SS18-SSX is a hallmark of synovial sarcomas. However, as a part of the SS18-SSX fusion protein, SS18's function remains unclear. Here, we depict the structures of both human SS18/BRG1 and yeast SNF11/SNF2 subcomplexes. Both subcomplexes assemble into heterodimers that share a similar conformation, suggesting that SNF11 might be a homologue of SS18 in chromatin remodeling complexes. Importantly, our study shows that the self-association of the intrinsically disordered region, QPGY domain, leads to liquid-liquid phase separation (LLPS) of SS18 or SS18-SSX and the subsequent recruitment of BRG1 into phase-separated condensates. Moreover, our results show that the tyrosine residues in the QPGY domain play a decisive role in the LLPS of SS18 or SS18-SSX. Perturbations of either SS18-SSX LLPS or SS18-SSX's binding to BRG1 impair NIH3T3 cell transformation by SS18-SSX. Our data demonstrate that both LLPS and assembling into chromatin remodelers contribute to the oncogenic activity of SS18-SSX in synovial sarcomas.
Topics: Animals; Cell Transformation, Neoplastic; Humans; Mice; NIH 3T3 Cells; Oncogene Proteins, Fusion; Proto-Oncogene Proteins; Repressor Proteins; Sarcoma, Synovial; Transcription Factors
PubMed: 35585082
DOI: 10.1038/s41467-022-30447-9 -
Cell Reports Jun 2022Dysregulated cellular metabolism is a cancer hallmark for which few druggable oncoprotein targets have been identified. Increased fatty acid (FA) acquisition allows...
Dysregulated cellular metabolism is a cancer hallmark for which few druggable oncoprotein targets have been identified. Increased fatty acid (FA) acquisition allows cancer cells to meet their heightened membrane biogenesis, bioenergy, and signaling needs. Excess FAs are toxic to non-transformed cells but surprisingly not to cancer cells. Molecules underlying this cancer adaptation may provide alternative drug targets. Here, we demonstrate that diacylglycerol O-acyltransferase 1 (DGAT1), an enzyme integral to triacylglyceride synthesis and lipid droplet formation, is frequently up-regulated in melanoma, allowing melanoma cells to tolerate excess FA. DGAT1 over-expression alone transforms p53-mutant zebrafish melanocytes and co-operates with oncogenic BRAF or NRAS for more rapid melanoma formation. Antagonism of DGAT1 induces oxidative stress in melanoma cells, which adapt by up-regulating cellular reactive oxygen species defenses. We show that inhibiting both DGAT1 and superoxide dismutase 1 profoundly suppress tumor growth through eliciting intolerable oxidative stress.
Topics: Animals; Diacylglycerol O-Acyltransferase; Melanoma; Oncogene Proteins; Oxidative Stress; Reactive Oxygen Species; Triglycerides; Zebrafish
PubMed: 35732120
DOI: 10.1016/j.celrep.2022.110995 -
Molecular Cell Mar 2022MLL rearrangements produce fusion oncoproteins that drive leukemia development, but the direct effects of MLL-fusion inactivation remain poorly defined. We designed...
MLL rearrangements produce fusion oncoproteins that drive leukemia development, but the direct effects of MLL-fusion inactivation remain poorly defined. We designed models with degradable MLL::AF9 where treatment with small molecules induces rapid degradation. We leveraged the kinetics of this system to identify a core subset of MLL::AF9 target genes where MLL::AF9 degradation induces changes in transcriptional elongation within 15 minutes. MLL::AF9 degradation subsequently causes loss of a transcriptionally active chromatin landscape. We used this insight to assess the effectiveness of small molecules that target members of the MLL::AF9 multiprotein complex, specifically DOT1L and MENIN. Combined DOT1L/MENIN inhibition resembles MLL::AF9 degradation, whereas single-agent treatment has more modest effects on MLL::AF9 occupancy and gene expression. Our data show that MLL::AF9 degradation leads to decreases in transcriptional elongation prior to changes in chromatin landscape at select loci and that combined inhibition of chromatin complexes releases the MLL::AF9 oncoprotein from chromatin globally.
Topics: Chromatin; Humans; Leukemia; Myeloid-Lymphoid Leukemia Protein; Oncogene Proteins, Fusion; Transcription Factors
PubMed: 35245435
DOI: 10.1016/j.molcel.2022.02.013 -
Cell Death & Disease Jan 2024A hallmark of tumor cells, including bladder cancer (BLCA) cells, is metabolic reprogramming toward aerobic glycolysis (Warburg effect). The classical oncogene MYC,...
A hallmark of tumor cells, including bladder cancer (BLCA) cells, is metabolic reprogramming toward aerobic glycolysis (Warburg effect). The classical oncogene MYC, which is crucial in regulating glycolysis, is amplified and activated in BLCA. However, direct targeting of the c-Myc oncoprotein, which regulates glycolytic metabolism, presents great challenges and necessitates the discovery of a more clarified regulatory mechanism to develop selective targeted therapy. In this study, a siRNA library targeting deubiquitinases identified a candidate enzyme named USP43, which may regulate glycolytic metabolism and c-Myc transcriptional activity. Further investigation using functional assays and molecular studies revealed a USP43/c-Myc positive feedback loop that contributes to the progression of BLCA. Moreover, USP43 stabilizes c-Myc by deubiquitinating c-Myc at K148 and K289 primarily through deubiquitinase activity. Additionally, upregulation of USP43 protein in BLCA increased the chance of interaction with c-Myc and interfered with FBXW7 access and degradation of c-Myc. These findings suggest that USP43 is a potential therapeutic target for indirectly targeting glycolytic metabolism and the c-Myc oncoprotein consequently enhancing the efficacy of bladder cancer treatment.
Topics: Humans; Proto-Oncogene Proteins c-myc; Glycolysis; RNA, Small Interfering; Urinary Bladder Neoplasms; Cell Line, Tumor; Cell Proliferation
PubMed: 38218970
DOI: 10.1038/s41419-024-06446-7 -
Clinical Biochemistry Jan 2021The Ski (Sloan-Kettering Institute) is an evolutionarily conserved protein that plays a dual role as an oncoprotein and tumor suppressor gene in the development of human... (Review)
Review
The Ski (Sloan-Kettering Institute) is an evolutionarily conserved protein that plays a dual role as an oncoprotein and tumor suppressor gene in the development of human cancer. The Ski oncogene was first identified as a transforming protein of the avian Sloan-Kettering retrovirus in 1986. Since its discovery, Ski has been identified as a carcinogenic regulator in a variety of malignant tumors. Later, it was reported that Ski regulates the occurrence and development of some cancers by acting as an oncogene. Ski mediates the proliferation, differentiation, metastasis, and invasion of numerous cancer cells through various mechanisms. Several studies have shown that Ski expression is correlated with the clinical characteristics of cancer patients and is a promising biomarker and therapeutic target for cancer. In this review, we summarize the mechanisms and potential clinical implications of Ski in dimorphism, cancer occurrence, and progression in various types of cancer.
Topics: Animals; DNA-Binding Proteins; Humans; Neoplasms; Proto-Oncogene Proteins; Signal Transduction
PubMed: 33188772
DOI: 10.1016/j.clinbiochem.2020.10.015 -
Nature Nov 2023The majority of oncogenic drivers are intracellular proteins, constraining their immunotherapeutic targeting to mutated peptides (neoantigens) presented by individual...
The majority of oncogenic drivers are intracellular proteins, constraining their immunotherapeutic targeting to mutated peptides (neoantigens) presented by individual human leukocyte antigen (HLA) allotypes. However, most cancers have a modest mutational burden that is insufficient for generating responses using neoantigen-based therapies. Neuroblastoma is a paediatric cancer that harbours few mutations and is instead driven by epigenetically deregulated transcriptional networks. Here we show that the neuroblastoma immunopeptidome is enriched with peptides derived from proteins essential for tumorigenesis. We focused on targeting the unmutated peptide QYNPIRTTF discovered on HLA-A*24:02, which is derived from the neuroblastoma-dependency gene and master transcriptional regulator PHOX2B. To target QYNPIRTTF, we developed peptide-centric chimeric antigen receptors (PC-CARs) through a counter panning strategy using predicted potentially cross-reactive peptides. We further proposed that PC-CARs can recognize peptides on additional HLA allotypes when presenting a similar overall molecular surface. Informed by our computational modelling results, we show that PHOX2B PC-CARs also recognize QYNPIRTTF presented by HLA-A*23:01, the most common non-A2 allele in people with African ancestry. Finally, we demonstrate potent and specific killing of neuroblastoma cells expressing these HLAs in vitro and complete tumour regression in mice. These data suggest that PC-CARs have the potential to expand the pool of immunotherapeutic targets to include non-immunogenic intracellular oncoproteins and allow targeting through additional HLA allotypes in a clinical setting.
Topics: Animals; Humans; Mice; Africa; Alleles; Amino Acid Sequence; Antigens, Neoplasm; Carcinogenesis; Cross Reactions; HLA-A Antigens; Neuroblastoma; Oncogene Proteins; Peptides; Receptors, Chimeric Antigen
PubMed: 37938771
DOI: 10.1038/s41586-023-06706-0 -
Cell Death & Disease Jun 2023Pediatric Acute Myeloid Leukemia (AML) is a rare and heterogeneous disease characterized by a high prevalence of gene fusions as driver mutations. Despite the...
Pediatric Acute Myeloid Leukemia (AML) is a rare and heterogeneous disease characterized by a high prevalence of gene fusions as driver mutations. Despite the improvement of survival in the last years, about 50% of patients still experience a relapse. It is not possible to improve prognosis only with further intensification of chemotherapy, as come with a severe cost to the health of patients, often resulting in treatment-related death or long-term sequels. To design more effective and less toxic therapies we need a better understanding of pediatric AML biology. The NUP98-KDM5A chimeric protein is exclusively found in a particular subgroup of young pediatric AML patients with complex karyotypes and poor prognosis. In this study, we investigated the impact of NUP98-KDM5A expression on cellular processes in human Pluripotent Stem Cell models and a patient-derived cell line. We found that NUP98-KDM5A generates genomic instability through two complementary mechanisms that involve accumulation of DNA damage and direct interference of RAE1 activity during mitosis. Overall, our data support that NUP98-KDM5A promotes genomic instability and likely contributes to malignant transformation.
Topics: Humans; Child; Oncogene Proteins, Fusion; Nuclear Pore Complex Proteins; Oncogene Proteins; Leukemia, Myeloid, Acute; Genomic Instability; Retinoblastoma-Binding Protein 2
PubMed: 37301844
DOI: 10.1038/s41419-023-05870-5