RESUMO
Minimal residual disease (MRD) analysis has become a powerful indicator to refine therapy in acute lymphoblastic leukemia (ALL). Here, we present an MRD detection based on the next-generation sequencing of PTEN exon 7 mutations (NGS-PTEN) in 30 pediatric T-cell ALL patients. By comparing the NGS-PTEN results with current quantitative PCR of antigen receptor gene rearrangements (qPCR-Ig/TR), an overall concordance of 80% was found between the two methods. However, the NGS-PTEN qualified a lower number of high-risk patients than qPCR-Ig/TR. These findings suggest that NGS-PTEN is a promising tool that could potentially be used to support current MRD methodologies for T-ALL patients.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Biomarcadores Tumorais/genética , Quimioterapia de Indução/efeitos adversos , Mutação , Neoplasia Residual/diagnóstico , PTEN Fosfo-Hidrolase/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamento farmacológico , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Neoplasia Residual/induzido quimicamente , Neoplasia Residual/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patologia , PrognósticoRESUMO
A main limitation of therapies that selectively target kinase signalling pathways is the emergence of secondary drug resistance. Cetuximab, a monoclonal antibody that binds the extracellular domain of epidermal growth factor receptor (EGFR), is effective in a subset of KRAS wild-type metastatic colorectal cancers. After an initial response, secondary resistance invariably ensues, thereby limiting the clinical benefit of this drug. The molecular bases of secondary resistance to cetuximab in colorectal cancer are poorly understood. Here we show that molecular alterations (in most instances point mutations) of KRAS are causally associated with the onset of acquired resistance to anti-EGFR treatment in colorectal cancers. Expression of mutant KRAS under the control of its endogenous gene promoter was sufficient to confer cetuximab resistance, but resistant cells remained sensitive to combinatorial inhibition of EGFR and mitogen-activated protein-kinase kinase (MEK). Analysis of metastases from patients who developed resistance to cetuximab or panitumumab showed the emergence of KRAS amplification in one sample and acquisition of secondary KRAS mutations in 60% (6 out of 10) of the cases. KRAS mutant alleles were detectable in the blood of cetuximab-treated patients as early as 10 months before radiographic documentation of disease progression. In summary, the results identify KRAS mutations as frequent drivers of acquired resistance to cetuximab in colorectal cancers, indicate that the emergence of KRAS mutant clones can be detected non-invasively months before radiographic progression and suggest early initiation of a MEK inhibitor as a rational strategy for delaying or reversing drug resistance.
Assuntos
Anticorpos Monoclonais/farmacologia , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Receptores ErbB/antagonistas & inibidores , Mutação/genética , Proteínas Proto-Oncogênicas/genética , Proteínas ras/genética , Alelos , Anticorpos Monoclonais/uso terapêutico , Anticorpos Monoclonais Humanizados , Linhagem Celular Tumoral , Cetuximab , Neoplasias Colorretais/patologia , Progressão da Doença , Resistencia a Medicamentos Antineoplásicos/genética , Genes ras/genética , Humanos , Quinases de Proteína Quinase Ativadas por Mitógeno/antagonistas & inibidores , Panitumumabe , Regiões Promotoras Genéticas/genética , Proteínas Proto-Oncogênicas p21(ras)RESUMO
BACKGROUND: Glioblastoma is a highly malignant brain tumor for which no cure is available. To identify new therapeutic targets, we performed a mutation analysis of kinase genes in glioblastoma. METHODS: Database mining and a literature search identified 76 kinases that have been found to be mutated at least twice in multiple cancer types before. Among those we selected 34 kinase genes for mutation analysis. We also included IDH1, IDH2, PTEN, TP53 and NRAS, genes that are known to be mutated at considerable frequencies in glioblastoma. In total, 174 exons of 39 genes in 113 glioblastoma samples from 109 patients and 16 high-grade glioma (HGG) cell lines were sequenced. RESULTS: Our mutation analysis led to the identification of 148 non-synonymous somatic mutations, of which 25 have not been reported before in glioblastoma. Somatic mutations were found in TP53, PTEN, IDH1, PIK3CA, EGFR, BRAF, EPHA3, NRAS, TGFBR2, FLT3 and RPS6KC1. Mapping the mutated genes into known signaling pathways revealed that the large majority of them plays a central role in the PI3K-AKT pathway. CONCLUSIONS: The knowledge that at least 50% of glioblastoma tumors display mutational activation of the PI3K-AKT pathway should offer new opportunities for the rational development of therapeutic approaches for glioblastomas. However, due to the development of resistance mechanisms, kinase inhibition studies targeting the PI3K-AKT pathway for relapsing glioblastoma have mostly failed thus far. Other therapies should be investigated, targeting early events in gliomagenesis that involve both kinases and non-kinases.
Assuntos
Análise Mutacional de DNA , Glioblastoma/enzimologia , Glioblastoma/genética , Fosfotransferases/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Linhagem Celular Tumoral , Feminino , GTP Fosfo-Hidrolases/genética , Humanos , Isocitrato Desidrogenase/genética , Sistema de Sinalização das MAP Quinases , Masculino , Proteínas de Membrana/genética , Pessoa de Meia-Idade , Mutação , PTEN Fosfo-Hidrolase/genética , Proteína Supressora de Tumor p53/genética , Adulto JovemRESUMO
Three genome-wide association studies in Europe and the USA have reported eight urinary bladder cancer (UBC) susceptibility loci. Using extended case and control series and 1000 Genomes imputations of 5 340 737 single-nucleotide polymorphisms (SNPs), we searched for additional loci in the European GWAS. The discovery sample set consisted of 1631 cases and 3822 controls from the Netherlands and 603 cases and 37 781 controls from Iceland. For follow-up, we used 3790 cases and 7507 controls from 13 sample sets of European and Iranian ancestry. Based on the discovery analysis, we followed up signals in the urea transporter (UT) gene SLC14A. The strongest signal at this locus was represented by a SNP in intron 3, rs17674580, that reached genome-wide significance in the overall analysis of the discovery and follow-up groups: odds ratio = 1.17, P = 7.6 × 10(-11). SLC14A1 codes for UTs that define the Kidd blood group and are crucial for the maintenance of a constant urea concentration gradient in the renal medulla and, through this, the kidney's ability to concentrate urine. It is speculated that rs17674580, or other sequence variants in LD with it, indirectly modifies UBC risk by affecting urine production. If confirmed, this would support the 'urogenous contact hypothesis' that urine production and voiding frequency modify the risk of UBC.
Assuntos
Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Proteínas de Membrana Transportadoras/genética , Neoplasias da Bexiga Urinária/genética , População Branca/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Cromossomos Humanos Par 18/genética , Progressão da Doença , Feminino , Loci Gênicos/genética , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética , Reprodutibilidade dos Testes , Fatores de Risco , Adulto Jovem , Transportadores de UreiaRESUMO
We used an approach that we term ancestry-shift refinement mapping to investigate an association, originally discovered in a GWAS of a Chinese population, between rs2046210[T] and breast cancer susceptibility. The locus is on 6q25.1 in proximity to the C6orf97 and estrogen receptor alpha (ESR1) genes. We identified a panel of SNPs that are correlated with rs2046210 in Chinese, but not necessarily so in other ancestral populations, and genotyped them in breast cancer case:control samples of Asian, European, and African origin, a total of 10,176 cases and 13,286 controls. We found that rs2046210[T] does not confer substantial risk of breast cancer in Europeans and Africans (OR = 1.04, P = 0.099, and OR = 0.98, P = 0.77, respectively). Rather, in those ancestries, an association signal arises from a group of less common SNPs typified by rs9397435. The rs9397435[G] allele was found to confer risk of breast cancer in European (OR = 1.15, P = 1.2 x 10(-3)), African (OR = 1.35, P = 0.014), and Asian (OR = 1.23, P = 2.9 x 10(-4)) population samples. Combined over all ancestries, the OR was 1.19 (P = 3.9 x 10(-7)), was without significant heterogeneity between ancestries (P(het) = 0.36) and the SNP fully accounted for the association signal in each ancestry. Haplotypes bearing rs9397435[G] are well tagged by rs2046210[T] only in Asians. The rs9397435[G] allele showed associations with both estrogen receptor positive and estrogen receptor negative breast cancer. Using early-draft data from the 1,000 Genomes project, we found that the risk allele of a novel SNP (rs77275268), which is closely correlated with rs9397435, disrupts a partially methylated CpG sequence within a known CTCF binding site. These studies demonstrate that shifting the analysis among ancestral populations can provide valuable resolution in association mapping.
Assuntos
Neoplasias da Mama/genética , Receptor alfa de Estrogênio/genética , Predisposição Genética para Doença/genética , Estudo de Associação Genômica Ampla/estatística & dados numéricos , Grupos Raciais/genética , Neoplasias da Mama/epidemiologia , Cromossomos Humanos Par 6 , Feminino , Loci Gênicos , Predisposição Genética para Doença/epidemiologia , Humanos , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Only a small proportion of cancers result from familial cancer syndromes with Mendelian inheritance. Nonfamilial, 'sporadic' cancers, which represent most cancer cases, also have a significant hereditary component, but the genes involved have low penetrance and are extremely difficult to detect. Therefore, mapping and cloning of quantitative trait loci (QTLs) for cancer susceptibility in animals could help identify homologous genes in humans. Several cancer-susceptibility QTLs have been mapped in mice and rats, but none have been cloned so far. Here we report the positional cloning of the mouse gene Scc1 (Susceptibility to colon cancer 1) and the identification of Ptprj, encoding a receptor-type protein tyrosine phosphatase, as the underlying gene. In human colon, lung and breast cancers, we show frequent deletion of PTPRJ, allelic imbalance in loss of heterozygosity (LOH) and missense mutations. Our data suggest that PTPRJ is relevant to the development of several different human cancers.
Assuntos
Adenocarcinoma/genética , Proteínas de Ciclo Celular/genética , Neoplasias do Colo/genética , Proteínas Tirosina Fosfatases/genética , Adenocarcinoma/patologia , Animais , Neoplasias da Mama/genética , Proteínas de Ciclo Celular/química , Proteínas Cromossômicas não Histona , Mapeamento Cromossômico , Neoplasias do Colo/induzido quimicamente , Dimetilidrazinas , Deleção de Genes , Inativação Gênica , Marcadores Genéticos , Humanos , Perda de Heterozigosidade , Neoplasias Pulmonares/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos , Proteínas Nucleares , Fosfoproteínas , Polimorfismo Genético , Característica Quantitativa Herdável , Proteínas Tirosina Fosfatases Classe 3 Semelhantes a Receptores , Proteínas de Saccharomyces cerevisiae , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido NucleicoRESUMO
A key challenge for the discovery of novel molecular targets and therapeutics against pediatric bone metastatic disease is the lack of bona fide in vitro cell models. Here, we show that a beta-tricalcium phosphate (ß-TCP) multicellular 3D in vitro bone microtissue model reconstitutes key phenotypic and transcriptional patterns of native metastatic tumor cells while promoting their stemness and proinvasive features. Comparing planar with interconnected channeled scaffolds, we identified geometry as a dominant orchestrator of proangiogenic traits in neuroblastoma tumor cells. On the other hand, the ß-TCP-determined gene signature was DNA replication related. Jointly, the geometry and chemical impact of ß-TCP revealed a prometastatic landscape of the engineered tumor microenvironment. The proposed 3D multicellular in vitro model of pediatric bone metastatic disease may advance further analysis of the molecular, genetic and metabolic bases of the disease and allow more efficient preclinical target validations.
RESUMO
Although a rare disease, rhabdomyosarcoma (RMS) is one of the most common cancers in children the more aggressive and metastatic subtype is the alveolar RMS (ARMS). Survival outcomes with metastatic disease remain dismal and the need for new models that recapitulate key pathological features, including cell-extracellular matrix (ECM) interactions, is warranted. Here, we report an organotypic model that captures cellular and molecular determinants of invasive ARMS. We cultured the ARMS cell line RH30 on a collagen sponge in a perfusion-based bioreactor (U-CUP), obtaining after 7 days a 3D construct with homogeneous cell distribution. Compared to static culture, perfusion flow induced higher cell proliferation rates (20% vs. 5%), enhanced secretion of active MMP-2, and upregulation of the Rho pathway, associated with cancer cell dissemination. Consistently, the ECM genes LAMA1 and LAMA2, the antiapoptotic gene HSP90, identified in patient databases as hallmarks of invasive ARMS, were higher under perfusion flow at mRNA and protein level. Our advanced ARMS organotypic model mimics (1) the interactions cells-ECM, (2) the cell growth maintenance, and (3) the expression of proteins that characterize tumor expansion and aggressiveness. In the future, the perfusion-based model could be used with primary patient-derived cell subtypes to create a personalized ARMS chemotherapy screening system.
Assuntos
Rabdomiossarcoma Alveolar , Rabdomiossarcoma , Criança , Humanos , Rabdomiossarcoma Alveolar/metabolismo , Linhagem Celular , Perfusão , Técnicas de Cultura de Células em Três Dimensões , Linhagem Celular TumoralRESUMO
The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has fueled the COVID-19 pandemic with its enduring medical and socioeconomic challenges because of subsequent waves and long-term consequences of great concern. Here, we chart the molecular basis of COVID-19 pathogenesis by analyzing patients' immune responses at single-cell resolution across disease course and severity. This approach confirms cell subpopulation-specific dysregulation in COVID-19 across disease course and severity and identifies a severity-associated activation of the receptor for advanced glycation endproducts (RAGE) pathway in monocytes. In vitro THP1-based experiments indicate that monocytes bind the SARS-CoV-2 S1-receptor binding domain (RBD) via RAGE, pointing to RAGE-Spike interaction enabling monocyte infection. Thus, our results demonstrate that RAGE is a functional receptor of SARS-CoV-2 contributing to COVID-19 severity.
Assuntos
COVID-19 , Humanos , Monócitos , Pandemias , Receptor para Produtos Finais de Glicação Avançada/genética , SARS-CoV-2RESUMO
BACKGROUND: Maintaining healthy mitochondria is mandatory for muscle viability and function. An essential surveillance mechanism targeting defective and harmful mitochondria to degradation is the selective form of autophagy called mitophagy. Ambra1 is a multifaceted protein with well-known autophagic and mitophagic functions. However, the study of its role in adult tissues has been extremely limited due to the embryonic lethality caused by full-body Ambra1 deficiency. METHODS: To establish the role of Ambra1 as a positive regulator of mitophagy, we exploited in vivo overexpression of a mitochondria-targeted form of Ambra1 in skeletal muscle. To dissect the consequence of Ambra1 inactivation in skeletal muscle, we generated muscle-specific Ambra1 knockout (Ambra1fl/fl :Mlc1f-Cre) mice. Mitochondria-enriched fractions were obtained from muscles of fed and starved animals to investigate the dynamics of the mitophagic flux. RESULTS: Our data show that Ambra1 has a critical role in the mitophagic flux of adult murine skeletal muscle and that its genetic inactivation leads to mitochondria alterations and myofibre remodelling. Ambra1 overexpression in wild-type muscles is sufficient to enhance mitochondria clearance through the autophagy-lysosome system. Consistently with this, Ambra1-deficient muscles display an abnormal accumulation of the mitochondrial marker TOMM20 by +76% (n = 6-7; P < 0.05), a higher presence of myofibres with swollen mitochondria by +173% (n = 4; P < 0.05), and an alteration in the maintenance of the mitochondrial membrane potential and a 34% reduction in the mitochondrial respiratory complex I activity (n = 4; P < 0.05). Lack of Ambra1 in skeletal muscle leads to impaired mitophagic flux, without affecting the bulk autophagic process. This is due to a significantly decreased recruitment of DRP1 (n = 6-7 mice; P < 0.01) and Parkin (n = 6-7 mice; P < 0.05) to the mitochondrial compartment, when compared with controls. Ambra1-deficient muscles also show a marked dysregulation of the endolysosome compartment, as the incidence of myofibres with lysosomal accumulation is 20 times higher than wild-type muscles (n = 4; P < 0.05). Histologically, Ambra1-deficient muscles of both 3- and 6-month-old animals display a significant decrease of myofibre cross-sectional area and a 52% reduction in oxidative fibres (n = 6-7; P < 0.05), thus highlighting a role for Ambra1 in the proper structure and activity of skeletal muscle. CONCLUSIONS: Our study indicates that Ambra1 is critical for skeletal muscle mitophagy and for the proper maintenance of functional mitochondria.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Mitocôndrias , Mitofagia , Músculo Esquelético , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Autofagia , Lisossomos/metabolismo , Camundongos , Mitocôndrias/metabolismo , Mitofagia/genética , Músculo Esquelético/metabolismoRESUMO
Patients with acute myeloid leukemia (AML) carrying high-risk genetic lesions or high residual disease levels after therapy are particularly exposed to the risk of relapse. Here, we identified the long non-coding RNA CDK6-AS1 able to cluster an AML subgroup with peculiar gene signatures linked to hematopoietic cell differentiation and mitochondrial dynamics. CDK6-AS1 silencing triggered hematopoietic commitment in healthy CD34+ cells, whereas in AML cells the pathological undifferentiated state was rescued. This latter phenomenon derived from RUNX1 transcriptional control, responsible for the stemness of hematopoietic precursors and for the block of differentiation in AML. By CDK6-AS1 silencing in vitro, AML mitochondrial mass decreased with augmented pharmacological sensitivity to mitochondria-targeting drugs. In vivo, the combination of tigecycline and cytarabine reduced leukemia progression in the AML-PDX model with high CDK6-AS1 levels, supporting the concept of a mitochondrial vulnerability. Together, these findings uncover CDK6-AS1 as crucial in myeloid differentiation and mitochondrial mass regulation.
RESUMO
Neuroblastoma (NB) is the most common extra-cranial malignancy in preschool children. To portray the genetic landscape of an overly aggressive NB leading to a rapid clinical progression of the disease, tumor DNA collected pre- and post-treatment has been analyzed. Array comparative genomic hybridization (aCGH), whole-exome sequencing (WES), and pharmacogenetics approaches, respectively, have identified relevant copy number alterations (CNAs), single nucleotide variants (SNVs), and polymorphisms (SNPs) that were then combined into an integrated analysis. Spontaneously formed 3D tumoroids obtained from the recurrent mass have also been characterized. The results prove the power of combining CNAs, SNVs, and SNPs analyses to assess clonal evolution during the disease progression by evidencing multiple clones at disease onset and dynamic genomic alterations during therapy administration. The proposed molecular and cytogenetic integrated analysis empowers the disease follow-up and the prediction of tumor recurrence.
Assuntos
Hibridização Genômica Comparativa , Sequenciamento do Exoma , Neuroblastoma/genética , Pré-Escolar , Progressão da Doença , Resistencia a Medicamentos Antineoplásicos/genética , Evolução Fatal , Humanos , Imunofenotipagem , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
The members of the BCL-2 associated athanogene (BAG) family participate in the regulation of a variety of interrelated physiological processes, such as autophagy, apoptosis, and protein homeostasis. Under normal circumstances, the six BAG members described in mammals (BAG1-6) principally assist the 70 kDa heat-shock protein (HSP70) in protein folding; however, their role as oncogenes is becoming increasingly evident. Deregulation of the BAG multigene family has been associated with cell transformation, tumor recurrence, and drug resistance. In addition to BAG overexpression, BAG members are also involved in many oncogenic protein-protein interactions (PPIs). As such, either the inhibition of overloading BAGs or of specific BAG-client protein interactions could have paramount therapeutic value. In this review, we will examine the role of each BAG family member in different malignancies, focusing on their modular structure, which enables interaction with a variety of proteins to exert their pro-tumorigenic role. Lastly, critical remarks on the unmet needs for proposing effective BAG inhibitors will be pointed out.
Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Neoplasias/genética , Neoplasias/metabolismo , Domínios e Motivos de Interação entre Proteínas/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Animais , Antineoplásicos/administração & dosagem , Antineoplásicos/metabolismo , Autofagia/fisiologia , Proteínas de Ligação a DNA/química , Humanos , Proteínas de Membrana/química , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Neoplasias/tratamento farmacológico , Oncogenes/fisiologia , Estrutura Secundária de Proteína , Fatores de Transcrição/químicaRESUMO
To overcome the lack of effective pharmacological treatments for high-risk neuroblastoma (HR-NB), the development of novel in vitro and in vivo models that better recapitulate the disease is required. Here, we used an in vitro multiclonal cell model encompassing NB cell differentiation stages, to identify potential novel pharmacological targets. This model allowed us to identify, by low-density RT-PCR arrays, two gene sets, one over-expressed during NB cell differentiation, and the other up-regulated in more malignant cells. Challenging two HR-NB gene expression datasets, we found that these two gene sets are related to high and low survival, respectively. Using mouse NB cisplatin-treated xenografts, we identified two genes within the list associated to the malignant stage (MCM2 and carbonic anhydrase 9), whose expression is positively correlated with tumor growth. Thus, we tested their pharmacological targeting as potential therapeutic strategy. We measured mice survival and tumor growth rate after xenografts of human NB treated with cisplatin in the presence of MCM2/carbonic anhydrase 9 inhibitors (ciprofloxacin and acetazolamide). MCM2 or carbonic anhydrase 9 inhibition significantly increased cisplatin activity, supporting their possible testing for NB therapy.
RESUMO
The RNA-binding protein LIN28B regulates developmental timing and determines stem cell identity by suppressing the let-7 family of microRNAs. Postembryonic reactivation of LIN28B impairs cell commitment to differentiation, prompting their transformation. In this study, we assessed the extent to which ectopic lin28b expression modulates the physiological behavior of neural crest cells (NCC) and governs their transformation in the trunk region of developing embryos. We provide evidence that the overexpression of lin28b inhibits sympathoadrenal cell differentiation and accelerates NCC migration in two vertebrate models, Xenopus leavis and Danio rerio. Our results highlight the relevance of ITGA5 and ITGA6 in the LIN28B-dependent regulation of the invasive motility of tumor cells. The results also establish that LIN28B overexpression supports neuroblastoma onset and the metastatic potential of malignant cells through let-7a-dependent and let-7a-independent mechanisms.
Assuntos
Movimento Celular , Crista Neural/citologia , Proteínas de Ligação a RNA/metabolismo , Células-Tronco/metabolismo , Sistema Simpático-Suprarrenal/citologia , Tronco/fisiologia , Proteínas de Xenopus/metabolismo , Proteínas de Peixe-Zebra/metabolismo , Animais , Diferenciação Celular , Linhagem Celular Tumoral , Transição Epitelial-Mesenquimal , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Adesões Focais/metabolismo , Humanos , Integrinas/metabolismo , Neurônios/citologia , Neurônios/metabolismo , Fenótipo , Transdução de Sinais , Xenopus laevis , Peixe-ZebraRESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
Plexins are transmembrane high-affinity receptors for semaphorins, regulating cell guidance, motility, and invasion. Functional evidences implicate semaphorin signals in cancer progression and metastasis. Yet, it is largely unknown whether plexin genes are genetically altered in human tumors. We performed a comprehensive gene copy analysis and mutational profiling of all nine members of the plexin gene family (plexinome), in melanomas and pancreatic ductal adenocarcinomas (PDACs), which are characterized by high metastatic potential and poor prognosis. Gene copy analysis detected amplification of PLXNA4 in melanomas, whereas copy number losses of multiple plexin genes were seen in PDACs. Somatic mutations were detected in PLXNA4, PLXNB3, and PLXNC1; providing the first evidence that these plexins are mutated in human cancer. Functional assays in cellular models revealed that some of these missense mutations result in loss of plexin function. For instance, c.1613G>A, p.R538H mutation in the extracellular domain of PLXNB3 prevented binding of the ligand Sema5A. Moreover, although PLXNA4 signaling can inhibit tumor cell migration, the mutated c.5206C>T, p.H1736Y allele had lost this activity. Our study is the first systematic analysis of the "plexinome" in human tumors, and indicates that multiple mutated plexins may be involved in cancer progression.
Assuntos
Adenocarcinoma/genética , Perfilação da Expressão Gênica , Melanoma/genética , Neoplasias Pancreáticas/genética , Receptores de Superfície Celular/genética , Humanos , Mutação , Filogenia , Reação em Cadeia da PolimeraseRESUMO
Monoclonal antibodies (mAbs) against the extracellular domain of the epidermal growth factor receptor (EGFR) have been introduced for the treatment of metastatic colorectal cancer (mCRC). We have reported recently that increased copy number of the EGFR can predict response to anti-EGFR mAbs and that patients might be selected for treatment based on EGFR copy number. Here, we show that mutations activating the RAS/RAF signaling pathway are also predictive and prognostic indicators in mCRC patients, being inversely correlated with response to anti-EGFR mAbs. In cellular models of CRCs, activation of the RAS signaling pathway by introduction of an activated K-RAS allele (Gly(12)Val) impairs the therapeutic effect of anti-EGFR mAbs. In cancer cells carrying constitutively active RAS, the pharmacologic inhibition of the mitogen-activated protein kinase (MAPK) signaling cascade improves anti-EGFR treatment based on mAbs. These results have implications for the identification of patients who are likely to respond to anti-EGFR treatment. They also provide the rationale for combination therapies, targeted simultaneously to the EGFR and RAS/RAF/MAPK signaling pathways in CRC patients.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Neoplasias Colorretais/genética , Quinases raf/genética , Quinases raf/metabolismo , Proteínas ras/genética , Proteínas ras/metabolismo , Adulto , Idoso , Alelos , Anticorpos Monoclonais Humanizados , Antineoplásicos/uso terapêutico , Cetuximab , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/terapia , Receptores ErbB/genética , Receptores ErbB/imunologia , Receptores ErbB/metabolismo , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Genes ras , Humanos , Sistema de Sinalização das MAP Quinases/genética , Masculino , Pessoa de Meia-Idade , PanitumumabeRESUMO
A recent systematic sequence analysis of well-annotated human protein coding genes or consensus coding sequences led to the identification of 189 genes displaying somatic mutations in breast and colorectal cancers. Based on their mutation prevalence, a subset of these genes was identified as cancer candidate (CAN) genes as they could be potentially involved in cancer. We evaluated the mutational profiles of 19 CAN genes in the highly aggressive tumors: glioblastoma, melanoma, and pancreatic carcinoma. Among other changes, we found novel somatic mutations in EPHA3, MLL3, TECTA, FBXW7, and OBSCN, affecting amino acids not previously found to be mutated in human cancers. Interestingly, we also found a germline nucleotide variant of OBSCN that was previously reported as a somatic mutation. Our results identify specific genetic lesions in glioblastoma, melanoma, and pancreatic cancers and indicate that CAN genes and their mutational profiles are tumor specific. Some of the mutated genes, such as the tyrosine kinase EPHA3, are clearly amenable to pharmacologic intervention and could represent novel therapeutic targets for these incurable cancers. We also speculate that similar to other oncogenes and tumor suppressor genes, mutations affecting OBSCN could be involved in cancer predisposition.
Assuntos
Glioblastoma/genética , Melanoma/genética , Neoplasias Pancreáticas/genética , Adulto , Idoso , Linhagem Celular Tumoral , Feminino , Genes Supressores de Tumor , Mutação em Linhagem Germinativa , Glioblastoma/patologia , Humanos , Masculino , Melanoma/patologia , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Oncogenes , Neoplasias Pancreáticas/patologia , Reação em Cadeia da PolimeraseRESUMO
HIF-1α has been suggested to interplay with Wnt signaling components in order to activate a neuronal differentiation process in both normal brain and glioblastoma (GBM). Based on these data, we explored the molecular mechanisms underlying the observed capability of GBM cells to acquire a neuronal phenotype upon Wnt signaling stimulation and how the microenvironment, particularly hypoxia, modulates this process. Methods: here, the employment of ChIP-seq techniques together with co-immunoprecipitation approaches allowed to reconstruct the molecular interactions responsible for activating specific pro-differentiating transcriptional programs in GBM cells. Moreover, gene silencing/over-expression approaches coupled with the functional analysis of cell phenotype were applied to confirm ChIP-driven hypotheses. Finally, we combined the use of publicly available gene expression datasets with protein expression data by immunohistochemistry to test the clinical relevance of obtained results. Results: our data clearly suggest that HIF-1α is recruited by the ß-catenin/TCF1 complex to foster neuronal differentiation gene transcription in hypoxic GBM cells. Conversely, at higher oxygen levels, the increased expression of TCF4 exerts a transcriptional inhibitory function on the same genomic regions, thus counteracting differentiation. Moreover, we demonstrate the existence of a positive correlation between the expression levels of HIF-1α, TCF1 and neuronal phenotype in GBM tumors, accompanied by the over-expression of several Wnt signaling components, finally affecting patient prognosis. Conclusion: we unveiled a peculiar mechanism by which TCF1 and HIF-1α can induce a reminiscent neuronal differentiation of hypoxic GBM cells, which is hampered, in normoxia, by high levels of TCF4, thus not only de facto controlling the balance between differentiation and stemness, but also impacting on intra-tumoral heterogeneity and eventually patient outcome.