Targeting of SUMOylation leads to cBAF complex stabilization and disruption of the SS18::SSX transcriptome in Synovial Sarcoma.

Synovial Sarcoma (SS) is driven by the SS18::SSX fusion oncoprotein and is ultimately refractory to therapeutic approaches. SS18::SSX alters ATP-dependent chromatin remodeling BAF (mammalian SWI/SNF) complexes, leading to the degradation of canonical (cBAF) complex and amplified presence of an SS18::SSX-containing non-canonical BAF (ncBAF or GBAF) that drives an SS-specific transcription program and tumorigenesis. We demonstrate that SS18::SSX activates the SUMOylation program and SSs are sensitive to the small molecule SAE1/2 inhibitor, TAK-981.

Targeting of SUMOylation leads to cBAF complex stabilization and disruption of the SS18::SSX transcriptome in Synovial Sarcoma.

Synovial Sarcoma (SS) is driven by the SS18::SSX fusion oncoprotein. and is ultimately refractory to therapeutic approaches. SS18::SSX alters ATP-dependent chromatin remodeling BAF (mammalian SWI/SNF) complexes, leading to the degradation of canonical (cBAF) complex and amplified presence of an SS18::SSX-containing non-canonical BAF (ncBAF or GBAF) that drives an SS-specific transcription program and tumorigenesis.

Pharmacologic Inhibition of SHP2 Blocks Both PI3K and MEK Signaling in Low-epiregulin HNSCC via GAB1.

Preclinical and clinical studies have evidenced that effective targeted therapy treatment against receptor tyrosine kinases (RTKs) in different solid tumor paradigms is predicated on simultaneous inhibition of both the PI3K and MEK intracellular signaling pathways. Indeed, re-activation of either pathway results in resistance to these therapies. Recently, oncogenic phosphatase SHP2 inhibitors have been developed with some now reaching clinical trials.

MYCN upregulates the transsulfuration pathway to suppress the ferroptotic vulnerability in -amplified neuroblastoma.

Ferroptosis is an iron-dependent, oxidative form of cell death that is countered mainly by glutathione peroxidase 4 (GPX4) and the production of glutathione (GSH), which is formed from cysteine. The identification of the cancers that may benefit from pharmacological ferroptotic induction is just emerging. We recently demonstrated that inducing ferroptosis genetically or pharmacologically in -amplified neuroblastoma (NB) is a novel and effective way to kill these cells.

Unmasking BCL-2 Addiction in Synovial Sarcoma by Overcoming Low NOXA.

Synovial sarcoma (SS) is frequently diagnosed in teenagers and young adults and continues to be treated with polychemotherapy with variable success. The SS18-SSX gene fusion is pathognomonic for the disease, and high expression of the anti-apoptotic BCL-2 pathologically supports the diagnosis. As the oncogenic SS18-SSX fusion gene itself is not druggable, BCL-2 inhibitor-based therapies are an appealing therapeutic opportunity.

Catastrophic ATP loss underlies a metabolic combination therapy tailored for -amplified neuroblastoma.

-amplified neuroblastoma is a lethal subset of pediatric cancer. MYCN drives numerous effects in the cell, including metabolic changes that are critical for oncogenesis. The understanding that both compensatory pathways and intrinsic redundancy in cell systems exists implies that the use of combination therapies for effective and durable responses is necessary.

Targeting transcription of MCL-1 sensitizes HER2-amplified breast cancers to HER2 inhibitors.

Human epidermal growth factor receptor 2 gene (HER2) is focally amplified in approximately 20% of breast cancers. HER2 inhibitors alone are not effective, and sensitizing agents will be necessary to move away from a reliance on heavily toxic chemotherapeutics. We recently demonstrated that the efficacy of HER2 inhibitors is mitigated by uniformly low levels of the myeloid cell leukemia 1 (MCL-1) endogenous inhibitor, NOXA.

-Amplified Neuroblastoma Is Addicted to Iron and Vulnerable to Inhibition of the System Xc-/Glutathione Axis.

is amplified in 20% to 25% of neuroblastoma, and -amplified neuroblastoma contributes to a large percent of pediatric cancer-related deaths. Therapy improvements for this subtype of cancer are a high priority. Here we uncover a MYCN-dependent therapeutic vulnerability in neuroblastoma.

Investigating New Mechanisms of Acquired Resistance to Targeted Therapies: If You Hit Them Harder, Do They Get Up Differently?

Targeted therapies have revolutionized treatment of several different types of cancers. However, in almost an invariable fashion, cancers eventually regrow in the presence of the targeted therapy, a phenomenon referred to as acquired resistance. In this issue of , Finn and colleagues demonstrate that modeling acquired resistance to MET tyrosine kinase inhibition in a -amplified gastric cancer cell line by a single, high exposure of the targeted therapy reveals clinically relevant acquired resistant mechanisms, which may be more faithful and comprehensive than the ones revealed through traditional ramp-up approaches.

The Ewing Family of Tumors Relies on BCL-2 and BCL-X to Escape PARP Inhibitor Toxicity.

Purpose: It was recently demonstrated that the translocation contributes to the hypersensitivity of Ewing sarcoma to PARP inhibitors, prompting clinical evaluation of olaparib in a cohort of heavily pretreated Ewing sarcoma tumors. Unfortunately, olaparib activity was disappointing, suggesting an underappreciated resistance mechanism to PARP inhibition in patients with Ewing sarcoma. We sought to elucidate the resistance factors to PARP inhibitor therapy in Ewing sarcoma and identify a rational drug combination capable of rescuing PARP inhibitor activity.

One gene to rule them all…and in the darkness bind them.

Pharmaceutical inhibition of the Human Epidermal growth factor Receptor 2 ( oncogene has dramatically improved outcomes in -amplified breast cancers. However, monotherapy HER2 inhibitors are not effective. We have recently reported that a co-amplified microRNA within the amplicon, leads to activation of the oncogene Myeloid Cell Leukemia-1 (), tempering cell death responses to HER2 inhibitors.

Targeted inhibition of histone H3K27 demethylation is effective in high-risk neuroblastoma.

High-risk neuroblastoma is often distinguished by amplification of and loss of differentiation potential. We performed high-throughput drug screening of epigenetic-targeted therapies across a large and diverse tumor cell line panel and uncovered the hypersensitivity of neuroblastoma cells to GSK-J4, a small-molecule dual inhibitor of lysine 27 of histone 3 (H3K27) demethylases ubiquitously transcribed tetratricopeptide repeat, X chromosome (UTX), and histone demethylase Jumonji D3 (JMJD3). Mechanistically, GSK-J4 induced neuroblastoma differentiation and endoplasmic reticulum (ER) stress, with accompanying up-regulation of p53 up-regulated modulator of apoptosis (PUMA) and induction of cell death.

Coamplification of protects -amplified breast cancers from targeted therapy.

() amplification is a driving oncogenic event in breast cancer. Clinical trials have consistently shown the benefit of HER2 inhibitors (HER2i) in treating patients with both local and advanced HER2+ breast cancer. Despite this benefit, their efficacy as single agents is limited, unlike the robust responses to other receptor tyrosine kinase inhibitors like EGFR inhibitors in -mutant lung cancer.

Venetoclax Is Effective in Small-Cell Lung Cancers with High BCL-2 Expression.

Small-cell lung cancer (SCLC) is an often-fatal neuroendocrine carcinoma usually presenting as extensive disease, carrying a 3% 5-year survival. Despite notable advances in SCLC genomics, new therapies remain elusive, largely due to a lack of druggable targets. We used a high-throughput drug screen to identify a venetoclax-sensitive SCLC subpopulation and validated the findings with multiple patient-derived xenografts of SCLC.

Epithelial-to-Mesenchymal Transition Antagonizes Response to Targeted Therapies in Lung Cancer by Suppressing BIM.

Epithelial-to-mesenchymal transition (EMT) confers resistance to a number of targeted therapies and chemotherapies. However, it has been unclear why EMT promotes resistance, thereby impairing progress to overcome it. We have developed several models of EMT-mediated resistance to EGFR inhibitors (EGFRi) in -mutant lung cancers to evaluate a novel mechanism of EMT-mediated resistance.

Epithelial-to-Mesenchymal Transition Defines Feedback Activation of Receptor Tyrosine Kinase Signaling Induced by MEK Inhibition in KRAS-Mutant Lung Cancer.

Unlabelled: KRAS is frequently mutated in lung cancer. Whereas MAPK is a well-known effector pathway of KRAS, blocking this pathway with clinically available MAPK inhibitors is relatively ineffective. Here, we report that epithelial-to-mesenchymal transition rewires the expression of receptor tyrosine kinases, leading to differential feedback activation of the MAPK pathway following MEK inhibition.

Exploitation of the Apoptosis-Primed State of MYCN-Amplified Neuroblastoma to Develop a Potent and Specific Targeted Therapy Combination.

Fewer than half of children with high-risk neuroblastoma survive. Many of these tumors harbor high-level amplification of MYCN, which correlates with poor disease outcome. Using data from our large drug screen we predicted, and subsequently demonstrated, that MYCN-amplified neuroblastomas are sensitive to the BCL-2 inhibitor ABT-199.

Mitochondrial shape governs BAX-induced membrane permeabilization and apoptosis.

Proapoptotic BCL-2 proteins converge upon the outer mitochondrial membrane (OMM) to promote mitochondrial outer membrane permeabilization (MOMP) and apoptosis. Here we investigated the mechanistic relationship between mitochondrial shape and MOMP and provide evidence that BAX requires a distinct mitochondrial size to induce MOMP. We utilized the terminal unfolded protein response pathway to systematically define proapoptotic BCL-2 protein composition after stress and then directly interrogated their requirement for a productive mitochondrial size.

BAK/BAX activation and cytochrome c release assays using isolated mitochondria.

The mitochondrial pathway of apoptosis proceeds when the outer mitochondrial membrane (OMM) is compromised by the pro-apoptotic BCL-2 family members, BAK and BAX. Once activated, BAK and BAX form proteolipid pores in the OMM leading to mitochondrial outer membrane permeabilization (MOMP), and the release of inner membrane space proteins, such as cytochrome c, which promotes caspase activation. The use of isolated mitochondria has been instrumental to understanding the key interactions necessary to engage BAK and BAX activation, MOMP, and apoptosis.

Overexpression of the novel member of the BCL2 gene family, BCL2L12, is associated with the disease outcome in patients with acute myeloid leukemia.

Objectives: BCL2L12 is a recently discovered and cloned gene from members of our research team. It is a novel member of the BCL2 gene family, members of which are implicated in different hematological malignancies. In the present study, we investigated and studied the expression profile of BCL2L12 in acute myeloid leukemia (AML).

The Role of BH3-Only Proteins in Tumor Cell Development, Signaling, and Treatment.

Tumor cells have devised several strategies to block the mitochondrial pathway of apoptosis despite endogenous or pharmacological cues to die. This process of cell death proceeds through the coordinated regulation of multiple anti-apoptotic and pro-apoptotic BCL-2 family proteins that ultimately impinge on the integrity of the outer mitochondrial membrane. Once compromised, mitochondria release pro-apoptotic factors to promote caspase activation and the apoptotic phenotype.

Molecular response of HL-60 cells to mitotic inhibitors vincristine and taxol visualized with apoptosis-related gene expressions, including the new member BCL2L12.

Taxol and vincristine belong to a group of anticancer drugs that target microtubules, subsequently arresting cells at the mitotic phase of the cell cycle and inducing programmed cell death. The BCL2 (bcl-2) family of genes is of known implication in apoptosis induced by various stimuli, among which BCL2L12, a new member of the family, cloned by our group. For further insights into the mechanisms and molecular targets implicated and modified as a result of apoptosis induced by these two mitosis-arresting drugs, we studied the possible alterations, at the mRNA level, of various apoptosis-related genes (BCL2, BAX, BCL2L12, CASPASE-3, FAS) after leukemia cell (HL-60) treatment with these drugs.