RESUMEN
Combination approaches are needed to strengthen and extend the clinical response to KRASG12C inhibitors (KRASG12Ci). Here, we assessed the antitumor responses of KRASG12C mutant lung and colorectal cancer models to combination treatment with a SOS1 inhibitor (SOS1i), BI-3406, plus the KRASG12C inhibitor, adagrasib. We found that responses to BI-3406 plus adagrasib were stronger than to adagrasib alone, comparable to adagrasib with SHP2 (SHP2i) or EGFR inhibitors and correlated with stronger suppression of RAS-MAPK signaling. BI-3406 plus adagrasib treatment also delayed the emergence of acquired resistance and elicited antitumor responses from adagrasib-resistant models. Resistance to KRASG12Ci seemed to be driven by upregulation of MRAS activity, which both SOS1i and SHP2i were found to potently inhibit. Knockdown of SHOC2, a MRAS complex partner, partially restored response to KRASG12Ci treatment. These results suggest KRASG12C plus SOS1i to be a promising strategy for treating both KRASG12Ci naive and relapsed KRASG12C-mutant tumors.
RESUMEN
PURPOSE: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) serve as the standard first-line therapy for EGFR-mutated non-small cell lung cancer (NSCLC). Despite the sustained clinical benefits achieved through optimal EGFR-TKI treatments, including the third-generation EGFR-TKI osimertinib, resistance inevitably develops. Currently, there are no targeted therapeutic options available postprogression on osimertinib. Here, we assessed the preclinical efficacy of BI-4732, a novel fourth-generation EGFR-TKI, using patient-derived preclinical models reflecting various clinical scenarios. EXPERIMENTAL DESIGN: The antitumor activity of BI-4732 was evaluated using Ba/F3 cells and patient-derived cell/organoid/xenograft models with diverse EGFR mutations. Intracranial antitumor activity of BI-4732 was evaluated in a brain-metastasis mouse model. RESULTS: We demonstrated the remarkable antitumor efficacy of BI-4732 as a single agent in various patient-derived models with EGFR_C797S-mediated osimertinib resistance. Moreover, BI-4732 exhibited activity comparable to osimertinib in inhibiting EGFR-activating (E19del and L858R) and T790M mutations. In a combination treatment strategy with osimertinib, BI-4732 exhibited a synergistic effect at significantly lower concentrations than those used in monotherapy. Importantly, BI-4732 displayed potent antitumor activity in an intracranial model, with low efflux at the blood-brain barrier. CONCLUSIONS: Our findings highlight the potential of BI-4732, a selective EGFR-TKI with high blood-brain barrier penetration, targeting a broad range of EGFR mutations, including C797S, warranting clinical development.
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Acrilamidas , Carcinoma de Pulmón de Células no Pequeñas , Indoles , Neoplasias Pulmonares , Pirimidinas , Ratones , Animales , Humanos , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/patología , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , Receptores ErbB/genética , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Mutación , Resistencia a Antineoplásicos/genética , Compuestos de AnilinaRESUMEN
Efforts to improve the anti-tumor response to KRASG12C targeted therapy have benefited from leveraging combination approaches. Here, we compare the anti-tumor response induced by the SOS1-KRAS interaction inhibitor, BI-3406, combined with a KRASG12C inhibitor (KRASG12Ci) to those induced by KRASG12Ci alone or combined with SHP2 or EGFR inhibitors. In lung cancer and colorectal cancer (CRC) models, BI-3406 plus KRASG12Ci induces an anti-tumor response stronger than that observed with KRASG12Ci alone and comparable to those by the other combinations. This enhanced anti-tumor response is associated with a stronger and extended suppression of RAS-MAPK signaling. Importantly, BI-3406 plus KRASG12Ci treatment delays the emergence of acquired adagrasib resistance in both CRC and lung cancer models and is associated with re-establishment of anti-proliferative activity in KRASG12Ci-resistant CRC models. Our findings position KRASG12C plus SOS1 inhibition therapy as a promising strategy for treating both KRASG12C-mutated tumors as well as for addressing acquired resistance to KRASG12Ci.
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Oncogenic alterations in human epidermal growth factor receptor 2 (HER2) occur in approximately 2% of patients with non-small cell lung cancer and predominantly affect the tyrosine kinase domain and cluster in exon 20 of the ERBB2 gene. Most clinical-grade tyrosine kinase inhibitors are limited by either insufficient selectivity against wild-type (WT) epidermal growth factor receptor (EGFR), which is a major cause of dose-limiting toxicity or by potency against HER2 exon 20 mutant variants. Here we report the discovery of covalent tyrosine kinase inhibitors that potently inhibit HER2 exon 20 mutants while sparing WT EGFR, which reduce tumor cell survival and proliferation in vitro and result in regressions in preclinical xenograft models of HER2 exon 20 mutant non-small cell lung cancer, concomitant with inhibition of downstream HER2 signaling. Our results suggest that HER2 exon 20 insertion-driven tumors can be effectively treated by a potent and highly selective HER2 inhibitor while sparing WT EGFR, paving the way for clinical translation.
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Carcinoma de Pulmón de Células no Pequeñas , Neoplasias Pulmonares , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Receptores ErbB/genética , Exones/genética , Genes erbB-2 , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/farmacología , Receptor ErbB-2/genéticaRESUMEN
KRAS is the most frequently mutated oncogene, harboring mutations in approximately one in seven cancers. Allele-specific KRASG12C inhibitors are currently changing the treatment paradigm for patients with KRASG12C-mutated non-small cell lung cancer and colorectal cancer. The success of addressing a previously elusive KRAS allele has fueled drug discovery efforts for all KRAS mutants. Pan-KRAS drugs have the potential to address broad patient populations, including KRASG12D-, KRASG12V-, KRASG13D-, KRASG12R-, and KRASG12A-mutant or KRAS wild-type-amplified cancers, as well as cancers with acquired resistance to KRASG12C inhibitors. Here, we review actively pursued allele-specific and pan-KRAS inhibition strategies and their potential utility. SIGNIFICANCE: Mutant-selective KRASG12C inhibitors target a fraction (approximately 13.6%) of all KRAS-driven cancers. A broad arsenal of KRAS drugs is needed to comprehensively conquer KRAS-driven cancers. Conceptually, we foresee two future classes of KRAS medicines: mutant-selective KRAS drugs targeting individual variant alleles and pan-KRAS therapeutics targeting a broad range of KRAS alterations.
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Carcinoma de Pulmón de Células no Pequeñas , Neoplasias Pulmonares , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/genética , Humanos , Mutación , Oncogenes , Medicina de Precisión , Proteínas Proto-Oncogénicas p21(ras)/genéticaRESUMEN
Cancer-associated, loss-of-function mutations in genes encoding subunits of the BRG1/BRM-associated factor (BAF) chromatin-remodeling complexes1-8 often cause drastic chromatin accessibility changes, especially in important regulatory regions9-19. However, it remains unknown how these changes are established over time (for example, immediate consequences or long-term adaptations), and whether they are causative for intracomplex synthetic lethalities, abrogating the formation or activity of BAF complexes9,20-24. In the present study, we use the dTAG system to induce acute degradation of BAF subunits and show that chromatin alterations are established faster than the duration of one cell cycle. Using a pharmacological inhibitor and a chemical degrader of the BAF complex ATPase subunits25,26, we show that maintaining genome accessibility requires constant ATP-dependent remodeling. Completely abolishing BAF complex function by acute degradation of a synthetic lethal subunit in a paralog-deficient background results in an almost complete loss of chromatin accessibility at BAF-controlled sites, especially also at superenhancers, providing a mechanism for intracomplex synthetic lethalities.
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Cromatina/genética , ADN Helicasas/metabolismo , Complejos Multiproteicos/genética , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , Acetilación , Animales , Línea Celular , Cromatina/metabolismo , ADN Helicasas/genética , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Drosophila/citología , Elementos de Facilitación Genéticos , Técnicas de Inactivación de Genes , Histonas/genética , Histonas/metabolismo , Humanos , Complejos Multiproteicos/metabolismo , Proteínas Nucleares/genética , Factores de Transcripción/genéticaRESUMEN
KRAS is the most frequently mutated driver of pancreatic, colorectal, and non-small cell lung cancers. Direct KRAS blockade has proved challenging, and inhibition of a key downstream effector pathway, the RAF-MEK-ERK cascade, has shown limited success because of activation of feedback networks that keep the pathway in check. We hypothesized that inhibiting SOS1, a KRAS activator and important feedback node, represents an effective approach to treat KRAS-driven cancers. We report the discovery of a highly potent, selective, and orally bioavailable small-molecule SOS1 inhibitor, BI-3406, that binds to the catalytic domain of SOS1, thereby preventing the interaction with KRAS. BI-3406 reduces formation of GTP-loaded RAS and limits cellular proliferation of a broad range of KRAS-driven cancers. Importantly, BI-3406 attenuates feedback reactivation induced by MEK inhibitors and thereby enhances sensitivity of KRAS-dependent cancers to MEK inhibition. Combined SOS1 and MEK inhibition represents a novel and effective therapeutic concept to address KRAS-driven tumors. SIGNIFICANCE: To date, there are no effective targeted pan-KRAS therapies. In-depth characterization of BI-3406 activity and identification of MEK inhibitors as effective combination partners provide an attractive therapeutic concept for the majority of KRAS-mutant cancers, including those fueled by the most prevalent mutant KRAS oncoproteins, G12D, G12V, G12C, and G13D.See related commentary by Zhao et al., p. 17.This article is highlighted in the In This Issue feature, p. 1.
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Neoplasias Pulmonares , Proteínas Proto-Oncogénicas p21(ras) , Línea Celular Tumoral , Humanos , Quinasas de Proteína Quinasa Activadas por Mitógenos , Mutación , Nucleótidos , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas p21(ras)/genéticaRESUMEN
Loss of WRN, a DNA repair helicase, was identified as a strong vulnerability of microsatellite instable (MSI) cancers, making WRN a promising drug target. We show that ATP binding and hydrolysis are required for genome integrity and viability of MSI cancer cells. We report a 2.2-Å crystal structure of the WRN helicase core (517-1,093), comprising the two helicase subdomains and winged helix domain but not the HRDC domain or nuclease domains. The structure highlights unusual features. First, an atypical mode of nucleotide binding that results in unusual relative positioning of the two helicase subdomains. Second, an additional ß-hairpin in the second helicase subdomain and an unusual helical hairpin in the Zn2+ binding domain. Modelling of the WRN helicase in complex with DNA suggests roles for these features in the binding of alternative DNA structures. NMR analysis shows a weak interaction between the HRDC domain and the helicase core, indicating a possible biological role for this association. Together, this study will facilitate the structure-based development of inhibitors against WRN helicase.
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Dominio Catalítico , Neoplasias Colorrectales/enzimología , Neoplasias Colorrectales/genética , Inestabilidad de Microsatélites , Helicasa del Síndrome de Werner/química , Helicasa del Síndrome de Werner/genética , Adenosina Difosfato/metabolismo , Adenosina Trifosfato/metabolismo , Proteínas de Ciclo Celular/genética , Supervivencia Celular/genética , Cristalización , ADN/metabolismo , Daño del ADN/genética , Silenciador del Gen , Células HCT116 , Humanos , Hidrólisis , Espectroscopía de Resonancia Magnética/métodos , Modelos Moleculares , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Proteínas Serina-Treonina Quinasas/genética , Proteínas Proto-Oncogénicas/genética , Transfección , Zinc/metabolismo , Quinasa Tipo Polo 1RESUMEN
Determining the site of cell cleavage is crucial for cytokinesis and involves precise activation of the RhoGEF ECT2. A new study demonstrates how a non-canonical interaction of ECT2 with centralspindlin underlies cytokinesis in animal cells, solving a mechanistic conundrum.
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Citocinesis , Fosfopéptidos , Animales , División Celular , Células HeLa , Humanos , Proteínas Proto-Oncogénicas/metabolismo , Proteína de Unión al GTP rhoARESUMEN
The cohesin subunit STAG2 has emerged as a recurrently inactivated tumor suppressor in human cancers. Using candidate approaches, recent studies have revealed a synthetic lethal interaction between STAG2 and its paralog STAG1 To systematically probe genetic vulnerabilities in the absence of STAG2, we have performed genome-wide CRISPR screens in isogenic cell lines and identified STAG1 as the most prominent and selective dependency of STAG2-deficient cells. Using an inducible degron system, we show that chemical genetic degradation of STAG1 protein results in the loss of sister chromatid cohesion and rapid cell death in STAG2-deficient cells, while sparing STAG2-wild-type cells. Biochemical assays and X-ray crystallography identify STAG1 regions that interact with the RAD21 subunit of the cohesin complex. STAG1 mutations that abrogate this interaction selectively compromise the viability of STAG2-deficient cells. Our work highlights the degradation of STAG1 and inhibition of its interaction with RAD21 as promising therapeutic strategies. These findings lay the groundwork for the development of STAG1-directed small molecules to exploit synthetic lethality in STAG2-mutated tumors.
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Proteínas de Ciclo Celular/deficiencia , Proteínas de Ciclo Celular/genética , Proteínas Cromosómicas no Histona/genética , Neoplasias/genética , Proteínas Nucleares/genética , Mutaciones Letales Sintéticas , Sistemas CRISPR-Cas , Proteínas de Ciclo Celular/metabolismo , Línea Celular Tumoral , Susceptibilidad a Enfermedades , Silenciador del Gen , Marcación de Gen , Estudio de Asociación del Genoma Completo , Humanos , Modelos Moleculares , Neoplasias/metabolismo , Neoplasias/patología , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Unión Proteica , Proteolisis , Relación Estructura-Actividad , CohesinasRESUMEN
In mammalian cell lines, the endosomal sorting complex required for transport (ESCRT)-III mediates abscission, the process that physically separates daughter cells and completes cell division. Cep55 protein is regarded as the master regulator of abscission, because it recruits ESCRT-III to the midbody (MB), the site of abscission. However, the importance of this mechanism in a mammalian organism has never been tested. Here we show that Cep55 is dispensable for mouse embryonic development and adult tissue homeostasis. Cep55-knockout offspring show microcephaly and primary neural progenitors require Cep55 and ESCRT for survival and abscission. However, Cep55 is dispensable for cell division in embryonic or adult tissues. In vitro, division of primary fibroblasts occurs without Cep55 and ESCRT-III at the midbody and is not affected by ESCRT depletion. Our work defines Cep55 as an abscission regulator only in specific tissue contexts and necessitates the re-evaluation of an alternative ESCRT-independent cell division mechanism.
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Proteínas de Ciclo Celular/metabolismo , Citocinesis , Células-Madre Neurales/citología , Células-Madre Neurales/metabolismo , Animales , Animales Recién Nacidos , Apoptosis , Proteínas de Ciclo Celular/deficiencia , Proteínas de Ciclo Celular/genética , Células Cultivadas , Corteza Cerebral/anomalías , Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Fibroblastos/metabolismo , Eliminación de Gen , Genotipo , Riñón/anomalías , Ratones Endogámicos C57BL , Ratones Noqueados , Microcefalia/patología , MitosisRESUMEN
Most metazoan cells entering mitosis undergo characteristic rounding, which is important for accurate spindle positioning and chromosome separation. Rounding is driven by contractile tension generated by myosin motors in the sub-membranous actin cortex. Recent studies highlight that alongside myosin activity, cortical actin organization is a key regulator of cortex tension. Yet, how mitotic actin organization is controlled remains poorly understood. To address this, we characterized the F-actin interactome in spread interphase and round mitotic cells. Using super-resolution microscopy, we then screened for regulators of cortex architecture and identified the intermediate filament vimentin and the actin-vimentin linker plectin as unexpected candidates. We found that vimentin is recruited to the mitotic cortex in a plectin-dependent manner. We then showed that cortical vimentin controls actin network organization and mechanics in mitosis and is required for successful cell division in confinement. Together, our study highlights crucial interactions between cytoskeletal networks during cell division.
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Citoesqueleto de Actina/fisiología , Actinas/metabolismo , Fenómenos Fisiológicos Celulares , Filamentos Intermedios/fisiología , Interfase/fisiología , Mitosis , Vimentina/metabolismo , Segregación Cromosómica , Células HeLa , HumanosRESUMEN
The epidermal growth factor receptor (EGFR), when carrying an activating mutation like del19 or L858R, acts as an oncogenic driver in a subset of lung tumors. While tumor responses to tyrosine kinase inhibitors (TKIs) are accompanied by marked tumor shrinkage, the response is usually not durable. Most patients relapse within two years of therapy often due to acquisition of an additional mutation in EGFR kinase domain that confers resistance to TKIs. Crucially, oncogenic EGFR harboring both resistance mutations, T790M and C797S, can no longer be inhibited by currently approved EGFR TKIs. Here, we describe the discovery of BI-4020, which is a noncovalent, wild-type EGFR sparing, macrocyclic TKI. BI-4020 potently inhibits the above-described EGFR variants and induces tumor regressions in a cross-resistant EGFRdel19â¯T790Mâ¯C797S xenograft model. Key was the identification of a highly selective but moderately potent benzimidazole followed by complete rigidification of the molecule through macrocyclization.
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Antineoplásicos/química , Antineoplásicos/farmacología , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacología , Animales , Antineoplásicos/farmacocinética , Bencimidazoles/química , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/patología , Línea Celular Tumoral , Cristalografía por Rayos X , Ciclización , Entropía , Receptores ErbB/antagonistas & inhibidores , Receptores ErbB/química , Receptores ErbB/genética , Femenino , Hepatocitos , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , Ratones , Ratones Transgénicos , Mutación , Conformación Proteica , Inhibidores de Proteínas Quinasas/farmacocinética , Relación Estructura-Actividad , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Aberrations in genes coding for subunits of the BRG1/BRM associated factor (BAF) chromatin remodeling complexes are highly abundant in human cancers. Currently, it is not understood how these mostly loss-of-function mutations contribute to cancer development and how they can be targeted therapeutically. The cancer-type-specific occurrence patterns of certain subunit mutations suggest subunit-specific effects on BAF complex function, possibly by the formation of aberrant residual complexes. Here, we systematically characterize the effects of individual subunit loss on complex composition, chromatin accessibility and gene expression in a panel of knockout cell lines deficient for 22 BAF subunits. We observe strong, specific and sometimes discordant alterations dependent on the targeted subunit and show that these explain intracomplex codependencies, including the synthetic lethal interactions SMARCA4-ARID2, SMARCA4-ACTB and SMARCC1-SMARCC2. These data provide insights into the role of different BAF subcomplexes in genome-wide chromatin organization and suggest approaches to therapeutically target BAF-mutant cancers.
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Ensamble y Desensamble de Cromatina/genética , ADN Helicasas/metabolismo , Proteínas de Unión al ADN/metabolismo , Mutación , Neoplasias/patología , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , ADN Helicasas/genética , Proteínas de Unión al ADN/genética , Humanos , Neoplasias/genética , Neoplasias/metabolismo , Proteínas Nucleares/genética , Factores de Transcripción/genética , TranscriptomaRESUMEN
SMARCA4/BRG1 and SMARCA2/BRM, the two mutually exclusive catalytic subunits of the BAF complex, display a well-established synthetic lethal relationship in SMARCA4-deficient cancers. Using CRISPR-Cas9 screening, we identify SMARCA4 as a novel dependency in SMARCA2-deficient esophageal squamous cell carcinoma (ESCC) models, reciprocal to the known synthetic lethal interaction. Restoration of SMARCA2 expression alleviates the dependency on SMARCA4, while engineered loss of SMARCA2 renders ESCC models vulnerable to concomitant depletion of SMARCA4. Dependency on SMARCA4 is linked to its ATPase activity, but not to bromodomain function. We highlight the relevance of SMARCA4 as a drug target in esophageal cancer using an engineered ESCC cell model harboring a SMARCA4 allele amenable to targeted proteolysis and identify SMARCA4-dependent cell models with low or absent SMARCA2 expression from additional tumor types. These findings expand the concept of SMARCA2/SMARCA4 paralog dependency and suggest that pharmacological inhibition of SMARCA4 represents a novel therapeutic opportunity for SMARCA2-deficient cancers.
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ADN Helicasas/antagonistas & inhibidores , Neoplasias Esofágicas/tratamiento farmacológico , Carcinoma de Células Escamosas de Esófago/tratamiento farmacológico , Proteínas Nucleares/antagonistas & inhibidores , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/genética , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Sistemas CRISPR-Cas/genética , Línea Celular Tumoral , Supervivencia Celular/genética , ADN Helicasas/genética , Epigénesis Genética , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/patología , Carcinoma de Células Escamosas de Esófago/genética , Carcinoma de Células Escamosas de Esófago/patología , Edición Génica , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Técnicas de Silenciamiento del Gen , Técnicas de Inactivación de Genes , Humanos , Mutación con Pérdida de Función , Terapia Molecular Dirigida/métodos , Proteínas Nucleares/genética , ARN Guía de Kinetoplastida/genética , ARN Interferente Pequeño/metabolismo , Mutaciones Letales Sintéticas , Factores de Transcripción/deficienciaRESUMEN
Here, we report the fragment-based discovery of BI-9321, a potent, selective and cellular active antagonist of the NSD3-PWWP1 domain. The human NSD3 protein is encoded by the WHSC1L1 gene located in the 8p11-p12 amplicon, frequently amplified in breast and squamous lung cancer. Recently, it was demonstrated that the PWWP1 domain of NSD3 is required for the viability of acute myeloid leukemia cells. To further elucidate the relevance of NSD3 in cancer biology, we developed a chemical probe, BI-9321, targeting the methyl-lysine binding site of the PWWP1 domain with sub-micromolar in vitro activity and cellular target engagement at 1 µM. As a single agent, BI-9321 downregulates Myc messenger RNA expression and reduces proliferation in MOLM-13 cells. This first-in-class chemical probe BI-9321, together with the negative control BI-9466, will greatly facilitate the elucidation of the underexplored biological function of PWWP domains.
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N-Metiltransferasa de Histona-Lisina/antagonistas & inhibidores , Proteínas Nucleares/antagonistas & inhibidores , Sistemas CRISPR-Cas , Línea Celular , Proliferación Celular/efectos de los fármacos , Supervivencia Celular , Regulación de la Expresión Génica/efectos de los fármacos , N-Metiltransferasa de Histona-Lisina/genética , N-Metiltransferasa de Histona-Lisina/metabolismo , Humanos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Dominios Proteicos , Proteínas Proto-Oncogénicas c-myc/genética , Proteínas Proto-Oncogénicas c-myc/metabolismoRESUMEN
Targeted cancer therapy is based on exploiting selective dependencies of tumor cells. By leveraging recent functional screening data of cancer cell lines we identify Werner syndrome helicase (WRN) as a novel specific vulnerability of microsatellite instability-high (MSI-H) cancer cells. MSI, caused by defective mismatch repair (MMR), occurs frequently in colorectal, endometrial and gastric cancers. We demonstrate that WRN inactivation selectively impairs the viability of MSI-H but not microsatellite stable (MSS) colorectal and endometrial cancer cell lines. In MSI-H cells, WRN loss results in severe genome integrity defects. ATP-binding deficient variants of WRN fail to rescue the viability phenotype of WRN-depleted MSI-H cancer cells. Reconstitution and depletion studies indicate that WRN dependence is not attributable to acute loss of MMR gene function but might arise during sustained MMR-deficiency. Our study suggests that pharmacological inhibition of WRN helicase function represents an opportunity to develop a novel targeted therapy for MSI-H cancers.
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Inestabilidad de Microsatélites , Neoplasias/terapia , Helicasa del Síndrome de Werner/antagonistas & inhibidores , Línea Celular Tumoral , Supervivencia Celular , Reparación de la Incompatibilidad de ADN , Humanos , Modelos Teóricos , Helicasa del Síndrome de Werner/genéticaRESUMEN
While the development of EGFR-targeted tyrosine kinase inhibitors (TKIs) has revolutionized treatment of EGFR mutation-positive non-small-cell lung cancer, acquired resistance to therapy is inevitable, reflecting tumor evolution. Recent studies show that EGFR mutation-positive non-small-cell lung cancer is highly heterogeneous at the cellular level, facilitating clonal expansion of resistant tumors via multiple molecular mechanisms. Here, we review the mechanistic differences between first-, second- and third-generation EGFR-targeted TKIs and speculate how these features could explain differences in clinical activity between these agents from a clonal evolution perspective. We hypothesize that the molecular dissection of tumor resistance mechanisms will facilitate optimal sequential use of EGFR TKIs in individual patients, thus maximizing the duration of chemotherapy-free treatment and survival benefit.
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Carcinoma de Pulmón de Células no Pequeñas/genética , Evolución Clonal/genética , Resistencia a Antineoplásicos/genética , Neoplasias Pulmonares/genética , Mutación , Animales , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Carcinoma de Pulmón de Células no Pequeñas/diagnóstico , Carcinoma de Pulmón de Células no Pequeñas/terapia , Receptores ErbB/genética , Heterogeneidad Genética , Humanos , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/terapia , Terapia Molecular DirigidaRESUMEN
Genotype specific vulnerabilities of cancer cells constitute a promising strategy for the development of new therapeutics. Deletions of non-essential genes in tumors can generate unique vulnerabilities which could be exploited therapeutically. The MTAP gene is recurrently deleted in human cancers because of its chromosomal proximity to the tumor suppressor gene CDKN2A. Recent studies have uncovered an increased dependency of MTAP-deleted cancer cells on the function of a PRMT5 containing complex, including WDR77, PRMT5 and the kinase RIOK1. As RIOK1 kinase activity constitutes a potential therapeutic target, we wanted to test if MTAP deletion confers increased sensitivity to RIOK1 inhibition. Using CRISPR/Cas9-mediated genome engineering we generated analog sensitive alleles of RIOK1 in isogenic cell lines differing only by MTAP status. While we were able to independently confirm an increased dependency of MTAP-deleted cells on PRMT5, we did not detect a differential requirement for RIOK1 kinase activity between MTAP-proficient and deficient cells. Our results reveal that the kinase activity of RIOK1 is required for the survival of cancer cell lines irrespective of their MTAP status and cast doubt on the therapeutic exploitability of RIOK1 in the context of MTAP-deleted cancers.
RESUMEN
Altered nuclear shape is a defining feature of cancer cells. The mechanisms underlying nuclear dysmorphia in cancer remain poorly understood. Here we identify PPP1R12A and PPP1CB, two subunits of the myosin phosphatase complex that antagonizes actomyosin contractility, as proteins safeguarding nuclear integrity. Loss of PPP1R12A or PPP1CB causes nuclear fragmentation, nuclear envelope rupture, nuclear compartment breakdown and genome instability. Pharmacological or genetic inhibition of actomyosin contractility restores nuclear architecture and genome integrity in cells lacking PPP1R12A or PPP1CB. We detect actin filaments at nuclear envelope rupture sites and define the Rho-ROCK pathway as the driver of nuclear damage. Lamin A protects nuclei from the impact of actomyosin activity. Blocking contractility increases nuclear circularity in cultured cancer cells and suppresses deformations of xenograft nuclei in vivo. We conclude that actomyosin contractility is a major determinant of nuclear shape and that unrestrained contractility causes nuclear dysmorphia, nuclear envelope rupture and genome instability.