RESUMEN
The PI3K signaling pathway is frequently mutated in head and neck squamous cell carcinoma (HNSCC), often via gain-of-function (GOF) mutations in the PIK3CA gene. Here, we present novel genetically engineered mouse models (GEMM) carrying a GOF allele Loxp-STOP-Loxp(LSL)-PIK3CAH1047R (E20) alone or in combination with heterozygous LSL-p53+/R172H (p53) mutation with tissue-specific expression to interrogate the role of oncogenic PIK3CA in transformation of upper aerodigestive track epithelium. We demonstrated that the GOF PIK3CA mutation promoted progression of 4-nitroquinoline 1-oxide-induced oral squamous cell carcinoma (OSCC) in both E20 single mutant and E20/p53 double mutant mice, with frequent distal metastasis detected only in E20/p53 GEMM. Similar to in human OSCC, loss of p16 was associated with progression of OSCC in these mice. RNA-seq analyses revealed that among the common genes differentially expressed in primary OSCC cell lines derived from E20, p53, and E20/p53 GEMMs compared with those from the wild-type mice, genes associated with proliferation and cell cycle were predominantly represented, which is consistent with the progressive loss of p16 detected in these GEMMs. Importantly, all of these OSCC primary cell lines exhibited enhanced sensitivity to BYL719 and cisplatin combination treatment in comparison with cisplatin alone in vitro and in vivo, regardless of p53 and/or p16 status. Given the prevalence of mutations in p53 and the PI3K pathways in HNSCC in conjunction with loss of p16 genetically or epigenetically, this universal increased sensitivity to cisplatin and BYL719 combination therapy in cancer cells with PIK3CA mutation represents an opportunity to a subset of patients with HNSCC. IMPLICATIONS: Our results suggest that combination therapy of cisplatin and PI3K inhibitor may be worthy of consideration in patients with HNSCC with PIK3CA mutation.
Asunto(s)
4-Nitroquinolina-1-Óxido/toxicidad , Fosfatidilinositol 3-Quinasa Clase I/genética , Neoplasias de Cabeza y Cuello/patología , Mutación , Carcinoma de Células Escamosas de Cabeza y Cuello/secundario , Proteína p53 Supresora de Tumor/genética , Animales , Carcinógenos/toxicidad , Progresión de la Enfermedad , Neoplasias de Cabeza y Cuello/inducido químicamente , Neoplasias de Cabeza y Cuello/genética , Ratones , Ratones Desnudos , Carcinoma de Células Escamosas de Cabeza y Cuello/inducido químicamente , Carcinoma de Células Escamosas de Cabeza y Cuello/genéticaRESUMEN
Regulation of RNA polymerase II (RNAPII)-mediated transcription controls cellular phenotypes such as cancer. Phosphatase and tensin homologue deleted on chromosome ten (PTEN), one of the most commonly altered tumor suppressors in cancer, affects transcription via its role in antagonizing the PI3K/AKT signaling pathway. Using co-immunoprecipitations and proximal ligation assays we provide evidence that PTEN interacts with AFF4, RNAPII, CDK9, cyclin T1, XPB and CDK7. Using ChIP-seq, we show that PTEN co-localizes with RNAPII and binds to chromatin in promoter and putative enhancer regions identified by histone modifications. Furthermore, we show that loss of PTEN affects RNAPII occupancy in gene bodies and further correlates with gene expression changes. Interestingly, PTEN binds to promoters and negatively regulates the expression of genes involved in transcription including AFF4 and POL2RA, which encodes a subunit of RNAPII. Loss of PTEN also increased cells' sensitivity to transcription inhibition via small molecules, which could provide a strategy to target PTEN-deficient cancers. Overall, our work describes a previously unappreciated role of nuclear PTEN, which by interacting with the transcription machinery in the context of chromatin exerts an additional layer of regulatory control on RNAPII-mediated transcription.
Asunto(s)
Cromatina/metabolismo , Fosfohidrolasa PTEN/metabolismo , ARN Polimerasa II/metabolismo , Transcripción Genética , Animales , Línea Celular , Células Cultivadas , Cromatina/genética , Células HEK293 , Células HeLa , Humanos , Ratones Endogámicos C57BL , Ratones Noqueados , Fosfohidrolasa PTEN/genética , Regiones Promotoras Genéticas/genética , Unión Proteica , ARN Polimerasa II/genética , Transducción de Señal/genética , Factores de Elongación Transcripcional/genética , Factores de Elongación Transcripcional/metabolismoRESUMEN
Estrogen dependence is major driver of ER + breast cancer, which is associated with PI3K mutation. PI3K inhibition (PI3Ki) can restore dependence on ER signaling for some hormone therapy-resistant ER + breast cancers, but is ineffective in others. Here we show that short-term supplementation with estrogen strongly enhanced Pik3caH1047R-induced mammary tumorigenesis in mice that resulted exclusively in ER + tumors, demonstrating the cooperation of the hormone and the oncogene in tumor development. Similar to human ER + breast cancers that are endocrine-dependent or endocrine-independent at diagnosis, tumor lines from this model retained ER expression but were sensitive or resistant to hormonal therapies. PI3Ki did not induce cell death but did cause upregulation of the pro-apoptotic gene BIM. BH3 mimetics or PI3Ki were unable to restore hormone sensitivity in several resistant mouse and human tumor lines. Importantly however, combination of PI3Ki and BH3 mimetics had a profound, BIM-dependent cytotoxic effect in PIK3CA-mutant cancer cells while sparing normal cells. We propose that addition of BH3 mimetics offers a therapeutic strategy to markedly improve the cytotoxic activity of PI3Ki in hormonal therapy-resistant and ER-independent PIK3CA-mutant breast cancer.
Asunto(s)
Compuestos de Anilina/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Proteínas Reguladoras de la Apoptosis/antagonistas & inhibidores , Apoptosis/efectos de los fármacos , Proteína Proapoptótica que Interacciona Mediante Dominios BH3/antagonistas & inhibidores , Proteína 11 Similar a Bcl2/agonistas , Estradiol , Receptor alfa de Estrógeno/fisiología , Neoplasias Mamarias Experimentales/tratamiento farmacológico , Proteínas de Neoplasias/fisiología , Neoplasias Hormono-Dependientes/tratamiento farmacológico , Neuropéptidos/antagonistas & inhibidores , Inhibidores de las Quinasa Fosfoinosítidos-3 , Sulfonamidas/farmacología , Tiazoles/farmacología , Compuestos de Anilina/administración & dosificación , Animales , Antineoplásicos Hormonales/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Proteína 11 Similar a Bcl2/biosíntesis , Proteína 11 Similar a Bcl2/genética , Proteína 11 Similar a Bcl2/fisiología , Línea Celular Tumoral , Fosfatidilinositol 3-Quinasa Clase I , Cocarcinogénesis , Resistencia a Antineoplásicos , Ensayos de Selección de Medicamentos Antitumorales , Sinergismo Farmacológico , Estradiol/toxicidad , Receptor alfa de Estrógeno/efectos de los fármacos , Femenino , Fulvestrant/administración & dosificación , Fulvestrant/farmacología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Técnicas de Sustitución del Gen , Neoplasias Mamarias Experimentales/inducido químicamente , Neoplasias Mamarias Experimentales/genética , Neoplasias Mamarias Experimentales/patología , Ratones , Ratones Desnudos , Mutación Missense , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/genética , Neoplasias Hormono-Dependientes/inducido químicamente , Neoplasias Hormono-Dependientes/genética , Neoplasias Hormono-Dependientes/patología , Fosfatidilinositol 3-Quinasas/genética , Fosfatidilinositol 3-Quinasas/fisiología , Sulfonamidas/administración & dosificación , Tiazoles/administración & dosificaciónRESUMEN
The PI3K signaling pathway is a complex and tightly regulated network that is critical for many physiologic processes, such as cell growth, proliferation, metabolism, and survival. Aberrant activation of this pathway can occur through mutation of almost any of its major nodes and has been implicated in a number of human diseases, including cancer. The high frequency of mutations in this pathway in multiple types of cancer has led to the development of small-molecule inhibitors of PI3K, several of which are currently in clinical trials. However, several feedback mechanisms either within the PI3K pathway or in compensatory pathways can render tumor cells resistant to therapy. Recently, targeting proteins of the bromodomain and extraterminal (BET) family of epigenetic readers of histone acetylation has been shown to effectively block adaptive signaling response of cancer cells to inhibitors of the PI3K pathway, which at least in some cases can restore sensitivity. BET inhibitors also enforce blockade of the MAPK, JAK/STAT, and ER pathways, suggesting they may be a rational combinatorial partner for divergent oncogenic signals that are subject to homeostatic regulation. Here, we review the PI3K pathway as a target for cancer therapy and discuss the potential use of BET inhibition to enhance the clinical efficacy of PI3K inhibitors. Clin Cancer Res; 22(11); 2605-10. ©2016 AACR.
Asunto(s)
Antineoplásicos/farmacología , Neoplasias/tratamiento farmacológico , Proteínas/antagonistas & inhibidores , Transducción de Señal , Antineoplásicos/uso terapéutico , Sinergismo Farmacológico , Epigénesis Genética/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Terapia Molecular Dirigida , Fosfatidilinositol 3-Quinasas/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéuticoRESUMEN
Unsustained enzyme inhibition is a barrier to targeted therapy for cancer. Here, resistance to a class I PI3K inhibitor in a model of metastatic breast cancer driven by PI3K and MYC was associated with feedback activation of tyrosine kinase receptors (RTKs), AKT, mTOR, and MYC. Inhibitors of bromodomain and extra terminal domain (BET) proteins also failed to affect tumor growth. Interestingly, BET inhibitors lowered PI3K signaling and dissociated BRD4 from chromatin at regulatory regions of insulin receptor and EGFR family RTKs to reduce their expression. Combined PI3K and BET inhibition induced cell death, tumor regression, and clamped inhibition of PI3K signaling in a broad range of tumor cell lines to provide a strategy to overcome resistance to kinase inhibitor therapy.
Asunto(s)
Neoplasias de la Mama/tratamiento farmacológico , Proteínas Nucleares/antagonistas & inhibidores , Inhibidores de las Quinasa Fosfoinosítidos-3 , Inhibidores de Proteínas Quinasas/farmacología , Factores de Transcripción/antagonistas & inhibidores , Animales , Apoptosis/efectos de los fármacos , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Proteínas de Ciclo Celular , Línea Celular , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Fosfatidilinositol 3-Quinasa Clase I , Sinergismo Farmacológico , Femenino , Humanos , Neoplasias Mamarias Experimentales/tratamiento farmacológico , Neoplasias Mamarias Experimentales/genética , Neoplasias Mamarias Experimentales/metabolismo , Ratones , Ratones Transgénicos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fosfatidilinositol 3-Quinasas/genética , Fosfatidilinositol 3-Quinasas/metabolismo , Dominios y Motivos de Interacción de Proteínas , Distribución Aleatoria , Transducción de Señal , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
BACKGROUND: The Tephritidae family of insects includes the most important agricultural pests of fruits and vegetables, belonging mainly to four genera (Bactrocera, Ceratitis, Anastrepha and Rhagoletis). The olive fruit fly, Bactrocera oleae, is the major pest of the olive fruit. Currently, its control is based on chemical insecticides. Environmentally friendlier methods have been attempted in the past (Sterile Insect Technique), albeit with limited success. This was mainly attributed to the lack of knowledge on the insect's behaviour, ecology and genetic structure of natural populations. The development of molecular markers could facilitate the access in the genome and contribute to the solution of the aforementioned problems. We chose to focus on microsatellite markers due to their abundance in the genome, high degree of polymorphism and easiness of isolation. RESULTS: Fifty-eight microsatellite-containing clones were isolated from the olive fly, Bactrocera oleae, bearing a total of sixty-two discrete microsatellite motifs. Forty-two primer pairs were designed on the unique sequences flanking the microsatellite motif and thirty-one of them amplified a PCR product of the expected size. The level of polymorphism was evaluated against wild and laboratory flies and the majority of the markers (93.5%) proved highly polymorphic. Thirteen of them presented a unique position on the olive fly polytene chromosomes by in situ hybridization, which can serve as anchors to correlate future genetic and cytological maps of the species, as well as entry points to the genome. Cross-species amplification of these markers to eleven Tephritidae species and sequencing of thirty-one of the amplified products revealed a varying degree of conservation that declines outside the Bactrocera genus. CONCLUSION: Microsatellite markers are very powerful tools for genetic and population analyses, particularly in species deprived of any other means of genetic analysis. The presented set of microsatellite markers possesses all features that would render them useful in such analyses. This could also prove helpful for species where SIT is a desired outcome, since the development of effective SIT can be aided by detailed knowledge at the genetic and molecular level. Furthermore, their presented efficacy in several other species of the Tephritidae family not only makes them useful for their analysis but also provides tools for phylogenetic comparisons among them.
Asunto(s)
Repeticiones de Microsatélite/genética , Tephritidae/genética , Animales , Evolución Molecular , Variación Genética , Genoma de los Insectos , Genotipo , Olea/parasitología , Filogenia , Polimorfismo Genético/genética , Especificidad de la EspecieRESUMEN
A genetic map based on microsatellite polymorphisms and visible mutations of the Mediterranean fruit fly (medfly), Ceratitis capitata is presented. Genotyping was performed on single flies from several backcross families. The map is composed of 67 microsatellites and 16 visible markers distributed over four linkage groups. Fluorescence in situ hybridization of selected microsatellite markers on salivary gland polytene chromosomes allowed the alignment of these groups to the second, fourth, fifth and sixth chromosome. None of the markers tested showed segregation either with the X or the third chromosome. However, this map constitutes a substantial starting point for a detailed genetic map of C. capitata. The construction of an integrated map covering the whole genome should greatly facilitate genetic studies and future genome sequence projects of the species.