RESUMEN
Small cell lung carcinoma (SCLC) is a highly lethal, smoking-associated cancer with few known targetable genetic alterations. Using genome sequencing, we characterized the somatic evolution of a genetically engineered mouse model (GEMM) of SCLC initiated by loss of Trp53 and Rb1. We identified alterations in DNA copy number and complex genomic rearrangements and demonstrated a low somatic point mutation frequency in the absence of tobacco mutagens. Alterations targeting the tumor suppressor Pten occurred in the majority of murine SCLC studied, and engineered Pten deletion accelerated murine SCLC and abrogated loss of Chr19 in Trp53; Rb1; Pten compound mutant tumors. Finally, we found evidence for polyclonal and sequential metastatic spread of murine SCLC by comparative sequencing of families of related primary tumors and metastases. We propose a temporal model of SCLC tumorigenesis with implications for human SCLC therapeutics and the nature of cancer-genome evolution in GEMMs.
Asunto(s)
Carcinogénesis , Modelos Animales de Enfermedad , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , Carcinoma Pulmonar de Células Pequeñas/genética , Carcinoma Pulmonar de Células Pequeñas/patología , Animales , Humanos , Neoplasias Hepáticas/secundario , Metástasis Linfática , Ratones , Fosfohidrolasa PTEN/genética , Fosfohidrolasa PTEN/metabolismo , Carcinoma Pulmonar de Células Pequeñas/secundarioRESUMEN
Genetically engineered mouse models (GEMMs) of cancer are increasingly being used to assess putative driver mutations identified by large-scale sequencing of human cancer genomes. To accurately interpret experiments that introduce additional mutations, an understanding of the somatic genetic profile and evolution of GEMM tumors is necessary. Here, we performed whole-exome sequencing of tumors from three GEMMs of lung adenocarcinoma driven by mutant epidermal growth factor receptor (EGFR), mutant Kirsten rat sarcoma viral oncogene homolog (Kras), or overexpression of MYC proto-oncogene. Tumors from EGFR- and Kras-driven models exhibited, respectively, 0.02 and 0.07 nonsynonymous mutations per megabase, a dramatically lower average mutational frequency than observed in human lung adenocarcinomas. Tumors from models driven by strong cancer drivers (mutant EGFR and Kras) harbored few mutations in known cancer genes, whereas tumors driven by MYC, a weaker initiating oncogene in the murine lung, acquired recurrent clonal oncogenic Kras mutations. In addition, although EGFR- and Kras-driven models both exhibited recurrent whole-chromosome DNA copy number alterations, the specific chromosomes altered by gain or loss were different in each model. These data demonstrate that GEMM tumors exhibit relatively simple somatic genotypes compared with human cancers of a similar type, making these autochthonous model systems useful for additive engineering approaches to assess the potential of novel mutations on tumorigenesis, cancer progression, and drug sensitivity.
Asunto(s)
Adenocarcinoma/genética , Transformación Celular Neoplásica/genética , Receptores ErbB/genética , Genes myc , Genes ras , Neoplasias Pulmonares/genética , Mutación , Adenocarcinoma/patología , Adenocarcinoma del Pulmón , Animales , Carcinógenos , Variaciones en el Número de Copia de ADN , Análisis Mutacional de ADN , Modelos Animales de Enfermedad , Dosificación de Gen , Estudio de Asociación del Genoma Completo , Neoplasias Pulmonares/patología , Ratones , Ratones Transgénicos , Mutación Puntual , Proto-Oncogenes Mas , Curva ROC , Secuenciación del ExomaRESUMEN
Thyroid cancer is the fifth most common cancer in women in the USA, and an estimated over 62â000 new cases occurred in men and women in 2015. The incidence continues to rise worldwide. Differentiated thyroid cancer is the most frequent subtype of thyroid cancer and in most patients the standard treatment (surgery followed by either radioactive iodine or observation) is effective. Patients with other, more rare subtypes of thyroid cancer-medullary and anaplastic-are ideally treated by physicians with experience managing these malignancies. Targeted treatments that are approved for differentiated and medullary thyroid cancers have prolonged progression-free survival, but these drugs are not curative and therefore are reserved for patients with progressive or symptomatic disease.
Asunto(s)
Carcinoma Neuroendocrino/diagnóstico , Carcinoma Neuroendocrino/cirugía , Supervivencia sin Enfermedad , Neoplasias de la Tiroides/diagnóstico , Neoplasias de la Tiroides/cirugía , Carcinoma Neuroendocrino/diagnóstico por imagen , Diagnóstico Diferencial , Humanos , Índice de Severidad de la Enfermedad , Neoplasias de la Tiroides/diagnóstico por imagen , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/fisiopatologíaRESUMEN
Anaplastic thyroid carcinoma (ATC) has among the worst prognoses of any solid malignancy. The low incidence of the disease has in part precluded systematic clinical trials and tissue collection, and there has been little progress in developing effective therapies. v-raf murine sarcoma viral oncogene homolog B (BRAF) and tumor protein p53 (TP53) mutations cooccur in a high proportion of ATCs, particularly those associated with a precursor papillary thyroid carcinoma (PTC). To develop an adult-onset model of BRAF-mutant ATC, we generated a thyroid-specific CreER transgenic mouse. We used a Cre-regulated Braf(V600E) mouse and a conditional Trp53 allelic series to demonstrate that p53 constrains progression from PTC to ATC. Gene expression and immunohistochemical analyses of murine tumors identified the cardinal features of human ATC including loss of differentiation, local invasion, distant metastasis, and rapid lethality. We used small-animal ultrasound imaging to monitor autochthonous tumors and showed that treatment with the selective BRAF inhibitor PLX4720 improved survival but did not lead to tumor regression or suppress signaling through the MAPK pathway. The combination of PLX4720 and the mapk/Erk kinase (MEK) inhibitor PD0325901 more completely suppressed MAPK pathway activation in mouse and human ATC cell lines and improved the structural response and survival of ATC-bearing animals. This model expands the limited repertoire of autochthonous models of clinically aggressive thyroid cancer, and these data suggest that small-molecule MAPK pathway inhibitors hold clinical promise in the treatment of advanced thyroid carcinoma.
Asunto(s)
Carcinoma/patología , Progresión de la Enfermedad , Mutación/genética , Proteínas Proto-Oncogénicas B-raf/genética , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/patología , Proteína p53 Supresora de Tumor/metabolismo , Animales , Carcinoma/sangre , Carcinoma/tratamiento farmacológico , Carcinoma/genética , Carcinoma Papilar , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/genética , Proliferación Celular/efectos de los fármacos , Modelos Animales de Enfermedad , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Homocigoto , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/genética , Ratones , Ratones Transgénicos , Quinasas de Proteína Quinasa Activadas por Mitógenos/antagonistas & inhibidores , Clasificación del Tumor , Inhibidores de Proteínas Quinasas/uso terapéutico , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Cáncer Papilar Tiroideo , Carcinoma Anaplásico de Tiroides , Glándula Tiroides/efectos de los fármacos , Glándula Tiroides/patología , Neoplasias de la Tiroides/sangre , Neoplasias de la Tiroides/tratamiento farmacológico , Tirotropina/sangreRESUMEN
Altered metabolism is a hallmark of cancer; however, it has been difficult to specifically target metabolism in cancer for therapeutic benefit. Cancers with genetically defined defects in metabolic enzymes constitute a subset of cancers where targeting metabolism is potentially accessible. Hürthle cell carcinoma of the thyroid (HTC) tumors frequently harbor deleterious mitochondrial DNA (mtDNA) mutations in subunits of complex I of the mitochondrial electron transport chain (ETC). Previous work has shown that HTC models with deleterious mtDNA mutations exhibit mitochondrial ETC defects that expose lactate dehydrogenase (LDH) as a therapeutic vulnerability. Here, we performed forward genetic screens to identify mechanisms of resistance to small-molecule LDH inhibitors. We identified two distinct mechanisms of resistance: upregulation of an LDH isoform and a compound-specific resistance mutation. Using these tools, we demonstrate that the anticancer activity of LDH inhibitors in cell line and xenograft models of complex I mutant HTC is through on-target LDH inhibition.
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Adenoma Oxifílico , L-Lactato Deshidrogenasa , Neoplasias de la Tiroides , Humanos , L-Lactato Deshidrogenasa/genética , L-Lactato Deshidrogenasa/metabolismo , Mutación , Mitocondrias/metabolismo , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/metabolismo , Neoplasias de la Tiroides/patología , ADN Mitocondrial/genéticaRESUMEN
Altered metabolism is a hallmark of cancer; however, it has been difficult to specifically target metabolism in cancer for therapeutic benefit. Cancers with genetically defined defects in metabolic enzymes constitute a subset of cancers where targeting metabolism is potentially accessible. Hürthle cell carcinoma of the thyroid (HTC) tumors frequently harbor deleterious mitochondrial DNA (mtDNA) mutations in subunits of complex I of the mitochondrial electron transport chain (ETC). Previous work has shown that HTC models with deleterious mtDNA mutations exhibit mitochondrial ETC defects that expose lactate dehydrogenase (LDH) as a therapeutic vulnerability. Here, we performed forward genetic screens to identify mechanisms of resistance to small molecule LDH inhibitors. We identified two distinct mechanisms of resistance: upregulation of an LDH isoform and a compound-specific resistance mutation. Using these tools, we demonstrate that the anti-cancer activity of LDH inhibitors in cell line and xenograft models of complex I-mutant HTC is through on-target LDH inhibition.
RESUMEN
A metabolic hallmark of cancer identified by Warburg is the increased consumption of glucose and secretion of lactate, even in the presence of oxygen. Although many tumors exhibit increased glycolytic activity, most forms of cancer rely on mitochondrial respiration for tumor growth. We report here that Hürthle cell carcinoma of the thyroid (HTC) models harboring mitochondrial DNA-encoded defects in complex I of the mitochondrial electron transport chain exhibit impaired respiration and alterations in glucose metabolism. CRISPR-Cas9 pooled screening identified glycolytic enzymes as selectively essential in complex I-mutant HTC cells. We demonstrate in cultured cells and a patient-derived xenograft model that small-molecule inhibitors of lactate dehydrogenase selectively induce an ATP crisis and cell death in HTC. This work demonstrates that complex I loss exposes fermentation as a therapeutic target in HTC and has implications for other tumors bearing mutations that irreversibly damage mitochondrial respiration. SIGNIFICANCE: HTC is enriched in somatic mtDNA mutations predicted to affect complex I of the electron transport chain (ETC). We demonstrate that these mutations impair respiration and induce a therapeutically tractable reliance on aerobic fermentation for cell survival. This work provides a rationale for targeting fermentation in cancers harboring irreversible genetically encoded ETC defects. See related article by Gopal et al., p. 1904. This article is highlighted in the In This Issue feature, p. 1749.
Asunto(s)
Adenocarcinoma , Adenoma Oxifílico , Carcinoma , Neoplasias de la Tiroides , Humanos , Fermentación , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/patología , Adenoma Oxifílico/genética , ADN Mitocondrial/genéticaRESUMEN
Orphan cytotoxins are small molecules for which the mechanism of action (MoA) is either unknown or ambiguous. Unveiling the mechanism of these compounds may lead to useful tools for biological investigation and in some cases, new therapeutic leads. In select cases, the DNA mismatch repair-deficient colorectal cancer cell line, HCT116, has been used as a tool in forward genetic screens to identify compound-resistant mutations, which have ultimately led to target identification. To expand the utility of this approach, we engineered cancer cell lines with inducible mismatch repair deficits, thus providing temporal control over mutagenesis. By screening for compound resistance phenotypes in cells with low or high rates of mutagenesis, we increased both the specificity and sensitivity of identifying resistance mutations. Using this inducible mutagenesis system, we implicate targets for multiple orphan cytotoxins, including a natural product and compounds emerging from a high-throughput screen, thus providing a robust tool for future MoA studies.
RESUMEN
Orphan cytotoxins are small molecules for which the mechanism of action (MoA) is either unknown or ambiguous. Unveiling the mechanism of these compounds may lead to useful tools for biological investigation and new therapeutic leads. In selected cases, the DNA mismatch repair-deficient colorectal cancer cell line, HCT116, has been used as a tool in forward genetic screens to identify compound-resistant mutations, which have ultimately led to target identification. To expand the utility of this approach, we engineered cancer cell lines with inducible mismatch repair deficits, thus providing temporal control over mutagenesis. By screening for compound resistance phenotypes in cells with low or high rates of mutagenesis, we increased both the specificity and sensitivity of identifying resistance mutations. Using this inducible mutagenesis system, we implicate targets for multiple orphan cytotoxins, including a natural product and compounds emerging from a high-throughput screen, thus providing a robust tool for future MoA studies.
Asunto(s)
Antineoplásicos , Neoplasias del Colon , Humanos , Reparación de la Incompatibilidad de ADN , Antineoplásicos/farmacología , Mutagénesis , CitotoxinasRESUMEN
Ewing sarcoma (EWS) is a pediatric malignancy driven by the EWSR1-FLI1 fusion protein formed by the chromosomal translocation t(11; 22). The small molecule TK216 was developed as a first-in-class direct EWSR1-FLI1 inhibitor and is in phase II clinical trials in combination with vincristine for patients with EWS. However, TK216 exhibits anti-cancer activity against cancer cell lines and xenografts that do not express EWSR1-FLI1, and the mechanism underlying cytotoxicity remains unresolved. We apply a forward-genetics screening platform utilizing engineered hypermutation in EWS cell lines and identify recurrent mutations in TUBA1B, encoding âº-tubulin, that prove sufficient to drive resistance to TK216. Using reconstituted microtubule (MT) polymerization in vitro and cell-based chemical probe competition assays, we demonstrate that TK216 acts as an MT destabilizing agent. This work defines the mechanism of cytotoxicity of TK216, explains the synergy observed with vincristine, and calls for a reexamination of ongoing clinical trials with TK216.
Asunto(s)
Antineoplásicos , Sarcoma de Ewing , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Línea Celular Tumoral , Niño , Regulación Neoplásica de la Expresión Génica , Humanos , Microtúbulos/metabolismo , Sarcoma de Ewing/tratamiento farmacológico , Sarcoma de Ewing/genética , Sarcoma de Ewing/patología , Vincristina/farmacología , Vincristina/uso terapéuticoRESUMEN
Mitochondrial electron transport chain (ETC) dysfunction due to mutations in the nuclear or mitochondrial genome is a common cause of metabolic disease in humans and displays striking tissue specificity depending on the affected gene. The mechanisms underlying tissue-specific phenotypes are not understood. Complex I (cI) is classically considered the entry point for electrons into the ETC, and in vitro experiments indicate that cI is required for basal respiration and maintenance of the NAD+/NADH ratio, an indicator of cellular redox status. This finding has largely not been tested in vivo. Here, we report that mitochondrial complex I is dispensable for homeostasis of the adult mouse liver; animals with hepatocyte-specific loss of cI function display no overt phenotypes or signs of liver damage, and maintain liver function, redox and oxygen status. Further analysis of cI-deficient livers did not reveal significant proteomic or metabolic changes, indicating little to no compensation is required in the setting of complex I loss. In contrast, complex IV (cIV) dysfunction in adult hepatocytes results in decreased liver function, impaired oxygen handling, steatosis, and liver damage, accompanied by significant metabolomic and proteomic perturbations. Our results support a model whereby complex I loss is tolerated in the mouse liver because hepatocytes use alternative electron donors to fuel the mitochondrial ETC.
Mitochondria are specialised structures inside cells that help to convert nutrients into energy. They take electrons from nutrients and use them to power biochemical reactions that supply chemical fuel. Previous studies of cells grown in the laboratory have found that electrons enter this process via a large assembly of proteins in mitochondria called complex I. Understanding the mechanism of energy production is important, as issues with mitochondria can lead to a variety of metabolic diseases. However, it is still unclear how complex I acts in living animals. Lesner et al. addressed this knowledge gap by genetically removing a key protein from complex I in the liver of mice. Surprisingly, the animals did not develop any detectable symptoms and maintained healthy liver function. Mice did not seem to compensate by making energy in a different way, suggesting that complex I is not normally used by the mouse liver for this process. This research suggests that biologists should reconsider the mechanism that mitochondria use to power cells in animals. While the role of Complex I in electron transfer is well established in laboratory-grown cells and some organs, like the brain, it cannot be assumed this applies to the whole body. Understanding energy production in specific organs could help researchers to develop nutrient-based therapies for metabolic diseases.
Asunto(s)
Complejo I de Transporte de Electrón , Proteómica , Animales , Ratones , Transporte de Electrón , Complejo I de Transporte de Electrón/genética , Complejo I de Transporte de Electrón/metabolismo , Hígado/metabolismo , Oxígeno/metabolismoRESUMEN
Muscle stem cells (MuSCs) experience age-associated declines in number and function, accompanied by mitochondrial electron transport chain (ETC) dysfunction and increased reactive oxygen species (ROS). The source of these changes, and how MuSCs respond to mitochondrial dysfunction, is unknown. We report here that in response to mitochondrial ROS, murine MuSCs directly fuse with neighboring myofibers; this phenomenon removes ETC-dysfunctional MuSCs from the stem cell compartment. MuSC-myofiber fusion is dependent on the induction of Scinderin, which promotes formation of actin-dependent protrusions required for membrane fusion. During aging, we find that the declining MuSC population accumulates mutations in the mitochondrial genome, but selects against dysfunctional variants. In the absence of clearance by Scinderin, the decline in MuSC numbers during aging is repressed; however, ETC-dysfunctional MuSCs are retained and can regenerate dysfunctional myofibers. We propose a model in which ETC-dysfunctional MuSCs are removed from the stem cell compartment by fusing with differentiated tissue.
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Músculos , Células Madre , Animales , Ratones , Transporte de Electrón , Especies Reactivas de Oxígeno/metabolismo , Células Madre/metabolismo , Músculos/metabolismoRESUMEN
Hürthle cell lesions have been a diagnostic conundrum in pathology since they were first recognized over a century ago. Controversy as to the name of the cell, the origin of the cell, and even which cells in particular may be designated as such still challenge pathologists and confound those treating patients with a diagnosis of "Hürthle cell" anything within the diagnosis, especially if that anything is a sizable mass lesion. The diagnosis of Hürthle cell adenoma (HCA) or Hürthle cell carcinoma (HCC) has typically relied on a judgement call by pathologists as to the presence or absence of capsular and/or vascular invasion of the adjacent thyroid parenchyma, easy to note in widely invasive disease and a somewhat subjective diagnosis for minimally invasive or borderline invasive disease. Diagnostic specificity, which has incorporated a sharp increase in molecular genetic studies of thyroid tumor subtypes and the integration of molecular testing into preoperative management protocols, continues to be challenged by Hürthle cell neoplasia. Here, we provide the improving yet still murky state of what is known about Hürthle cell tumor genetics, clinical management, and based upon what we are learning about the genetics of other thyroid tumors, how to manage expectations, by pathologists, clinicians, and patients, for more actionable, precise classifications of Hürthle cell tumors of the thyroid.
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Adenoma Oxifílico , Neoplasias de la Tiroides , Adenoma Oxifílico/diagnóstico , Adenoma Oxifílico/genética , Adenoma Oxifílico/patología , Adenoma Oxifílico/terapia , Biopsia , Genoma Mitocondrial/genética , Humanos , Mutación , Células Oxífilas/patología , Células Oxífilas/fisiología , Neoplasias de la Tiroides/diagnóstico , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/patología , Neoplasias de la Tiroides/terapia , TiroidectomíaRESUMEN
Mitochondria play an essential role in cellular metabolism, generation of reactive oxygen species (ROS), and the initiation of apoptosis. These properties enable mitochondria to be crucial integrators in the pathways of tumorigenesis. An open question is to what extent variation in the mitochondrial genome (mtDNA) contributes to the biological heterogeneity observed in human tumors. In this review, we summarize our current understanding of the role of mtDNA genetics in relation to human cancers.
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Carcinogénesis/genética , ADN Mitocondrial/genética , Genes Modificadores , Genoma Mitocondrial , Neoplasias/genética , Apoptosis/genética , Heterogeneidad Genética , Haplotipos , Humanos , Mutación con Pérdida de Función , Neoplasias/patología , Especies Reactivas de Oxígeno/metabolismoRESUMEN
A phenotypic high-throughput screen identified a benzamide small molecule with activity against small cell lung cancer cells. A "clickable" benzamide probe was designed that irreversibly bound a single 50 kDa cellular protein, identified by mass spectrometry as ß-tubulin. Moreover, the anti-cancer potency of a series of benzamide analogs strongly correlated with probe competition, indicating that ß-tubulin was the functional target. Additional evidence suggested that benzamides covalently modified Cys239 within the colchicine binding site. Consistent with this mechanism, benzamides impaired growth of microtubules formed with ß-tubulin harboring Cys239, but not ß3 tubulin encoding Ser239. We therefore designed an aldehyde-containing analog capable of trapping Ser239 in ß3 tubulin, presumably as a hemiacetal. Using a forward genetics strategy, we identified benzamide-resistant cell lines harboring a Thr238Ala mutation in ß-tubulin sufficient to induce compound resistance. The disclosed chemical probes are useful to identify other colchicine site binders, a frequent target of structurally diverse small molecules.
Asunto(s)
Antineoplásicos/farmacología , Benzamidas/química , Colchicina/metabolismo , Microtúbulos/efectos de los fármacos , Carcinoma Pulmonar de Células Pequeñas/tratamiento farmacológico , Moduladores de Tubulina/farmacología , Tubulina (Proteína)/química , Antineoplásicos/química , Sitios de Unión , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/patología , Microtúbulos/metabolismo , Conformación Proteica , Carcinoma Pulmonar de Células Pequeñas/patología , Relación Estructura-Actividad , Tubulina (Proteína)/genética , Tubulina (Proteína)/metabolismo , Moduladores de Tubulina/químicaRESUMEN
Hürthle cell tumors (HCT), including Hürthle cell adenomas (HCA) and Hürthle cell carcinomas (HCCs), arise in the thyroid gland and are defined in part by an accumulation of mitochondria. These neoplasms were long considered a subtype of follicular neoplasm, although HCT is now generally considered a distinct entity. HCTs exhibit overlapping but distinct clinical features compared to follicular tumors, and several studies have demonstrated that HCTs harbor distinct genomic alterations compared to other forms of thyroid cancer. Two studies recently reported the most complete characterization of the HCC genome to date. These studies assessed complementary cohorts of HCC specimens. The study by Ganly et al. consisted of a large panel of primary HCCs, including 32 widely invasive and 24 minimally invasive primary tumors. Exome and RNA sequencing of material isolated from fresh-frozen tumor specimens was performed. The study by Gopal et al. utilized exome and targeted sequencing to characterize the nuclear and mitochondrial genomes of 32 primary tumors and 38 resected regional and distant metastases using DNA isolated from formalin-fixed paraffin-embedded tissues. Here, HCC is briefly reviewed in the context of these studies.
Asunto(s)
Adenoma Oxifílico/genética , Biomarcadores de Tumor/genética , Neoplasias de la Tiroides/genética , Adenoma Oxifílico/diagnóstico por imagen , Adenoma Oxifílico/patología , Adenoma Oxifílico/terapia , Cromosomas Humanos , ADN Mitocondrial/genética , Reordenamiento Génico , Predisposición Genética a la Enfermedad , Humanos , Pérdida de Heterocigocidad , Mutación , Fenotipo , Pronóstico , Factores de Riesgo , Neoplasias de la Tiroides/diagnóstico por imagen , Neoplasias de la Tiroides/patología , Neoplasias de la Tiroides/terapiaRESUMEN
Target identification for biologically active small molecules remains a major barrier for drug discovery. Cancer cells exhibiting defective DNA mismatch repair (dMMR) have been used as a forward genetics system to uncover compound targets. However, this approach has been limited by the dearth of cancer cell lines that harbor naturally arising dMMR. Here, we establish a platform for forward genetic screening using CRISPR/Cas9 to engineer dMMR into mammalian cells. We demonstrate the utility of this approach to identify mechanisms of drug action in mouse and human cancer cell lines using in vitro selections against three cellular toxins. In each screen, compound-resistant alleles emerged in drug-resistant clones, supporting the notion that engineered dMMR enables forward genetic screening in mammalian cells.
Asunto(s)
Descubrimiento de Drogas/métodos , Ingeniería Genética/métodos , Pruebas Genéticas/métodos , Animales , Sistemas CRISPR-Cas/genética , Línea Celular Tumoral , Repeticiones Palindrómicas Cortas Agrupadas y Regularmente Espaciadas/genética , Reparación de la Incompatibilidad de ADN/genética , Humanos , Ratones , Neoplasias/genéticaRESUMEN
Congenital heart disease in humans results from abnormal morphogenesis of the embryonic cardiovascular system. The characterization of mutations affecting cardiovascular development in animal models ranging from flies to mice has identified many of the key signaling molecules and transcriptional regulators of heart formation. Many of these molecules are also mutated in familial forms of human congenital heart disease. Through the use of animal models combined with analysis of human pedigrees, a molecular framework that controls formation of the vertebrate heart is beginning to emerge.
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Corazón/embriología , Animales , Linaje de la Célula , Humanos , Cresta Neural/embriologíaRESUMEN
Hürthle cell carcinoma of the thyroid (HCC) is a form of thyroid cancer recalcitrant to radioiodine therapy that exhibits an accumulation of mitochondria. We performed whole-exome sequencing on a cohort of primary, recurrent, and metastatic tumors, and identified recurrent mutations in DAXX, TP53, NRAS, NF1, CDKN1A, ARHGAP35, and the TERT promoter. Parallel analysis of mtDNA revealed recurrent homoplasmic mutations in subunits of complex I of the electron transport chain. Analysis of DNA copy-number alterations uncovered widespread loss of chromosomes culminating in near-haploid chromosomal content in a large fraction of HCC, which was maintained during metastatic spread. This work uncovers a distinct molecular origin of HCC compared with other thyroid malignancies.
Asunto(s)
Aberraciones Cromosómicas , ADN Mitocondrial/genética , Mutación , Neoplasias de la Tiroides/genética , Variaciones en el Número de Copia de ADN , Haploidia , Humanos , Metástasis de la Neoplasia , Telomerasa/genética , Neoplasias de la Tiroides/patología , Secuenciación del ExomaRESUMEN
PURPOSE: To determine whether the selective BRAF inhibitor, dabrafenib, can stimulate radioiodine uptake in BRAF V600E-mutated unresectable or metastatic iodine-refractory papillary thyroid cancer (PTC). EXPERIMENTAL DESIGN: Ten patients with BRAF V600E-mutant iodine-refractory PTC were enrolled. Absence of radioiodine uptake on iodine-131 whole body scan obtained within 14 months of study entry was required. Each patient received dabrafenib (150 mg twice daily) for 25 days before thyrotropin α-stimulated iodine-131 whole body scan (4 mCi/148 MBq). Patients whose scan showed new sites of radioiodine uptake remained on dabrafenib for 17 more days, and then were treated with 150 mCi (5.5 GBq) iodine-131. The primary endpoint of the study was the percentage of patients with new radioiodine uptake after treatment with dabrafenib. RESULTS: Six of 10 patients (60%) demonstrated new radioiodine uptake on whole body scan after treatment with dabrafenib. All 6 were treated with 5.5 GBq iodine-131. Two patients had partial responses and 4 patients had stable disease on standard radiographic restaging at 3 months. Thyroglobulin decreased in 4 of 6 treated patients. One patient developed squamous cell carcinoma of the skin. There were no other significant adverse events attributed to dabrafenib. CONCLUSIONS: Dabrafenib can stimulate radioiodine uptake in patients with metastatic BRAF V600E-mutant iodine-refractory PTC, representing a potential new therapeutic approach for these patients.