Name: focus formation: a cell-based assay to determine the oncogenic potential of a gene
Uploaded: 2014-12-31T15:00:00.000+00:00
Duration: 8 min 18 s
Description: Watch this Scientific Journal Video about Focus Formation: A Cell-based Assay to Determine the Oncogenic Potential of a Gene at JoVE.com

Este trabajo fue apoyado por una beca del Programa de Premios Nueva Innovador del director del NIH (ED). AA fue financiada en parte por los premios de licenciatura del Instituto Nacional del Cáncer y la Fundación Nacional de Ciencia.

1. Hacer los vectores virales Las secuencias de codificación para el gen de interés, así como los controles positivos y negativos, se insertan en pBabePuro por los métodos tradicionales de clonación (amplificación por PCR, digestión de restricción y ligadura). Hay cuatro sitios de restricción en el vector donde se puede insertar el ADN: BamHI, SnaBI, EcoRI y SalI. <ol><li> Preparar transfección grado plásmido de ADN a partir de células competentes utilizando el kit de plásmido QIAGEN midi. </li><li> Medir la concentración de ADN usando un espectrofotómetro NanoDrop2000. </li></ol> 2. Retrovirus Producción La línea celular de empaquetamiento Plat-E se puede utilizar para producir retrovirus ecotrópico que entregará el ADNc de interés a las células NIH 3T3. <ol><li> Establecer Plat-E culturas de células congeladas <ol><li> Descongelar rápidamente las células Plat-E en un baño de agua ° C 37 y transferir a un tubo cónico de 15 ml. Poco a poco agregue 9 ml de medio Plat-E (DuMedio Eagle Modificado de lbecco (DMEM) + 10% de suero bovino fetal (FBS) + penicilina y estreptomicina). </li><li> Centrifugar el tubo a 180 x g durante 5 min y descartar el sobrenadante. </li><li> Vuelva a suspender las células con 10 ml de medio Plat-E y la transferencia a una placa de cultivo de 10 cm. </li><li> Se incuban las células en un 37 ° C, 5% de CO 2 incubadora hasta que son 80-90% de confluencia (aproximadamente 2 días). </li></ol></li><li> La división celular <ol><li> Aspirar el medio y lavar las células una vez con PBS. </li><li> Añadir 2 ml de 0,05% de tripsina-EDTA y se incuba durante 1 min a TA. </li><li> Separe las células por el dedo de tapping, añadir 10 ml de medio Plat-E, y transferir la suspensión celular a un tubo de 15 ml. </li><li> Centrifugar el tubo a 180 x g durante 5 min y descartar el sobrenadante. </li><li> Resuspender las células con 10 ml de medio Plat-E y sembrar en nuevos platos en 1: 4-1: 6 diluciones. </li></ol></li><li> Plat-E Siembra y transfección <ol><li> Semilla 2 x 10 6células por placa de 10 cm de cultivo utilizando medio Plat-E sin antibióticos. </li><li> Se incuban las células O / N en un 37 ° C, 5% de CO 2 incubadora. </li><li> Al día siguiente, la transferencia de 300 l de Opti-MEM en 1,5 ml tubo de microcentrífuga. </li><li> Añadir 27 l de polietilenimina (PEI), un reactivo de transfección rentable 12, al tubo preparado con Opti-MEM. Mezclar suavemente por el dedo tocando e incubar durante 5 min a TA. </li><li> Añadir 9 g de ADN plásmido de grado de transfección en el tubo de Opti-MEM / PEI, mezclar suavemente mediante agitación con vórtex, y se incuba durante 15 min a TA. </li><li> Añadir el ADN / PEI complejo gota a gota en el plato Plat-E, e incubar O / N a 37 ° C, 5% de CO 2. </li><li> Al día siguiente, aspirar el medio que contiene el reactivo de transfección y agregar 10 ml de medio Plat-E fresco (sin antibióticos). </li><li> Devolver las células a la incubadora. </li></ol></li></ol> 3. Las células NIH 3T3 y la infección <ol><li> El establecimiento de los NIHCulturas 3T3 y Siembra <ol><li> Descongelar rápidamente las células NIH 3T3 en un baño de agua ° C 37 y transferir a un tubo de 15 ml. Poco a poco agregue 9 ml de medio NIH 3T3 (DMEM + 10% FBS). </li><li> Centrifugar el tubo a 180 x g durante 5 min y descartar el sobrenadante. </li><li> Resuspender las células con 10 ml de medio y la transferencia de NIH 3T3 a una placa de cultivo de 10 cm. </li><li> Se incuban las células en un 37 ° C, 5% de CO 2 incubadora. Es muy importante que las células NIH 3T3 se mantienen siempre underconfluent (50-60%), como la frecuencia de transformación espontánea (y, por tanto, los niveles basales de la formación de focos) aumenta una vez al cultivo alcanza la confluencia. </li><li> Seed 3 x 10 5 células por placa de 10 cm y se incuban O / N para la infección el día siguiente. </li></ol></li><li> Infección <ol><li> Se recoge el sobrenadante retroviral de la placa de Plat-E mediante el uso de una jeringa desechable de 10 ml, filtrándola a través de un filtro de membrana de nylon de 0,45 micras de tamaño de poro, y transferir en un 15 mltubo. </li><li> Añadir 10 ml de medio Plat-E fresco a las células (sin antibióticos), y devolverlos a la incubadora. </li><li> Aspirar el medio de la placa de células NIH 3T3 de estar infectados, y añadir 5 ml de medio regular de NIH 3T3 y 5 ml de sobrenadante filtrado que contiene el virus. </li><li> Añadir al plato polibreno a una concentración de 6 mg / ml. </li><li> Se incuban las células O / N a 37 ° C, 5% de CO 2. </li><li> Al día siguiente, repita los pasos 3.2.1 - 3.2.5 para una segunda ronda de la infección. </li><li> Sustituya el medio que contiene el virus con medio normal NIH 3T3. </li><li> Permitir que las células NIH 3T3 crecer durante 2-3 semanas, reemplazando el medio según sea necesario. Compruebe expresión de la proteína de interés por electroforesis de proteínas convencional y inmunoblot sobre lisados ​​de células enteras de placas de réplica. </li></ol></li></ol> 4. La tinción y cuantificación <ol><li> Tinción con cristal violeta <ol><li> Aspirar el medio NIH 3T3 y coloque los platosen hielo. </li><li> Lavar los platos dos veces con helado de PBS. </li><li> Fijar las células con metanol enfriado con hielo durante 10 min. </li><li> Quitar los platos de hielo, aspirar el metanol, y añadir 3 ml de solución de cristal violeta al 0,5% hechos en 25% de metanol (RT). </li><li> Incubar los platos durante 5 min a RT. </li><li> Aspirar la solución de cristal violeta y enjuague cuidadosamente el plato con Milli-Q H 2 O hasta que no hay color sale en el enjuague. </li><li> Deje que los platos se sequen O / N en una mesa de trabajo (al descubierto). </li></ol></li><li> Focos Cuantificación <ol><li> Una vez que los platos están secos, use una regla para medir las colecciones de color oscuro de las células en el plato. Sólo contar los que son mayores que 5 mm de diámetro como &quot;focos&quot;. Registrar el número de focos y calcular los promedios y la importancia en comparación con los controles. </li></ol></li></ol>

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La FFA proporciona un método rápido y fácil de evaluar la transformación maligna in vitro. Es susceptible a la detección de un número relativamente grande de genes candidatos, y sus requisitos técnicos modestos que sea rentable. Además, dos o más genes pueden ser coexpressed (a veces conocido como un ensayo de la &quot;cooperación&quot;) para evaluar el potencial tumorigénico de la combinación. Las ventajas de este ensayo se basan en su técnica sencilla, su facilidad de cuantificación y su relativ...

Las células tumorales se pueden distinguir de sus homólogos normales por una amplia gama de alteraciones, a partir de patrones de expresión génica a epigenomics a cambios morfológicos y proliferativas. Entre estos últimos, la reducción de la dependencia de suero, la pérdida de contacto (densidad) la inhibición, la adquisición de la proliferación independiente de anclaje y, en última instancia, la capacidad de formar tumores cuando se inyectan en animales son útiles, indicadores medibles de la transformación maligna 3. Varios in vitro y en ensayos in vivo se han desarrollado para la transformación celular. Los ensayos in vitro como objetivo la identificación y medición de los cambios en la morfología de cultivo (ensayo de formación de foco), la dinámica de cultivo (tasa de crecimiento, densidad de saturación) y factor de crecimiento (crecimiento en el suero reducida) o fondeadero (crecimiento en agar blando) requisitos. El estándar de oro para la determinación de la naturaleza maligna de un tipo de célula sigue siendo la formación de tumores (xenoinjertos) en animales de experimentación. Sin embargo, tl costo y la duración de los estudios in vivo no siempre hacen justificable como un primer paso de validación o screening de oncogenes candidatos. Aunque no hay ensayo in vitro proporciona una evaluación definitiva de la potencial oncogénico de un gen, que no proporcionan información sobre potencial oncogénico que pueden reducir futuro en estudios in vivo. Uno de los sistemas más utilizados para evaluar el potencial oncogénico in vitro es la formación de ensayo Focus 2. Este enfoque se basa en el uso de NIH 3T3 de fibroblastos de ratón, una línea de células no transformadas que muestra la inhibición por contacto fuerte. La sobreexpresión de un oncogén resultados en pérdida de crecimiento dependiente de la densidad; a continuación, las células transformadas pueden crecer en múltiples capas, formando &quot;focos&quot;, fácil de visualizar contra la monocapa de fondo de células no transformadas. La formación de focos de ensayo, a continuación, mide la capacidad de un oncogén candidato para inducir la transformación maligna, como lo demuestra la pérdida de contacto inhibition como un fenotipo medible. El FFA ha sido utilizado para evaluar la transformación por la sobreexpresión de las proteínas quinasas (por ejemplo, Src 4, 5 BRAF), factores de transcripción (por ejemplo, N-myc 6) receptores, G acoplados a la proteína (por ejemplo, P2RY8 7) y GTPasas (por ejemplo, , Ras 1), entre otros. La relativa facilidad de este ensayo hace que sea una buena opción que proporcionará una respuesta rápida y visualmente claro si la sobreexpresión del gen es suficiente para transformar células de fibroblastos de ratón NIH 3T3 in vitro. El FFA se describe en este protocolo utiliza la línea celular de empaquetamiento Plat-E 8, que proporciona proteínas de empaquetamiento virales, y el vector retroviral pBabePuro 9 (Addgene plásmido 1764) para producir retrovirus. Después de la transfección con el constructo de pBabePuro que contiene el gen de interés, la línea celular Plat-E producirá retrovirus ecotrópico que se puede utilizar para infectar células NIH 3T3. Tsu método viral del suministro de genes es más eficiente que los métodos de transfección química tradicionales y ofrece una manera de expresar el gen sostenible 10. Una vez incorporado en el genoma de las células NIH 3T3, la sobreexpresión del gen de interés es impulsado por el promotor viral repeticiones terminales largas (LTR) 11. Esta expresión constante se puede utilizar para determinar si el gen de interés tiene actividad oncogénica, medida por la formación de focos, en las células NIH 3T3.

<table><tbody><tr><td>pBABE-puro vector</td><td>Addgene</td><td>Plasmid 1764</td><td>cloning vector</td></tr><tr><td>Platinum-E Retroviral Packaging Cell Line, Ecotropic</td><td>Cell Biolabs, Inc.</td><td>RV-101</td><td>cell line for viral production</td></tr><tr><td>NIH 3T3 Cell Line murine</td><td>Sigma-Aldrich</td><td>93061524</td><td>cell line for focus formation assay</td></tr><tr><td>10 ml BD Luer-Lok tip syringe</td><td>BD Biosciences</td><td>309604</td><td>viral production reagent</td></tr><tr><td>0.45 &amp;mu;m Puradisc Syringe Filter</td><td>Whatman</td><td>6750-2504</td><td>viral production reagent</td></tr><tr><td>Polyethylenimine (PEI)</td><td>Polysciences, Inc.</td><td>23966-2</td><td>cell transfection reagent</td></tr><tr><td>Polybrene Infection / Transfection Reagent</td><td>EMD Millipore</td><td>TR-1003-G</td><td>cell transfection reagent</td></tr><tr><td>Crystal Violet</td><td>Fisher Scientific</td><td>C581-25</td><td>cell stain reagent</td></tr><tr><td>Plasmid Plus Midi Kit</td><td>QIAGEN</td><td>12945</td><td>plasmid purification</td></tr><tr><td>BD Falcon Tissue Culture Dishes</td><td>BD Biosciences</td><td>353003</td><td>cell culture supplies</td></tr><tr><td>Dulbecco&#039;s Modified Eagle Medium (DMEM)</td><td>Gibco</td><td>11995-065</td><td>cell culture media</td></tr><tr><td>0.05% Trypsin-EDTA</td><td>Gibco</td><td>25300-054</td><td>cell culture supplies</td></tr><tr><td>Opti-MEM I Reduced Serum Medium</td><td>Gibco</td><td>31985-062</td><td>cell culture media</td></tr><tr><td>Fetal Bovine Serum (FBS)</td><td>Gibco</td><td>16000-044</td><td>cell culture media</td></tr></tbody></table>

focus formation: a cell-based assay to determine the oncogenic potential of a gene

Malignant transformation of cells is typically associated with increased proliferation, loss of contact inhibition, acquisition of anchorage-independent growth potential, and the ability to form tumors in experimental animals1. In NIH 3T3 cells, the Ras signal transduction pathway is known to trigger many of these events, what is known as Ras transformation. The introduction of an overexpressed gene in NIH 3T3 cells may promote morphological transformation and loss of contact inhibition, which can help determine the oncogenic potential of that gene of interest. An assay that provides a straightforward method to assess one aspect of the transforming potential of an oncogene is the Focus Formation Assay (FFA)2. When NIH 3T3 cells divide normally in culture, they do so until they reach a confluent monolayer. However, in the presence of an overexpressed oncogene, these cells can begin to grow in dense, multilayered foci1 that can be visualized and quantified by crystal violet or Hema 3 staining. In this article we describe the FFA protocol with retroviral transduction of the gene of interest into NIH 3T3 cells, and how to quantify the number of foci through staining. Retroviral transduction offers a more efficient method of gene delivery than transfection, and the use of an ecotropic murine retrovirus provides a biosafety control when working with potential human oncogenes.

MXD3 es un factor de transcripción de la cremallera de leucina básica hélice-bucle-hélice (bHLHZ) que es un miembro de la MYC / MAX / MAD red. Es un miembro atípico de la familia MAD 13-15, y se ha informado a participar en la carcinogénesis 16,17. Cuando se compara con pBabePuro (control negativo) y MYC (control positivo), los platos NIH 3T3 donde se sobreexpresa MXD3 tuvieron significativamente menos focos (Figura 1A). Los datos en la Figura 1B se recogiero...

Watch this Scientific Journal Video about Focus Formation: A Cell-based Assay to Determine the Oncogenic Potential of a Gene at JoVE.com

Focus Formation: A Cell-based Assay to Determine the Oncogenic Potential of a Gene

El ensayo Focus Formación ofrece un método sencillo para evaluar el potencial de transformación de un oncogén candidato.

Enfoque Formación: Un análisis basado en células para determinar el potencial oncogénico de un gen

Malignant transformation of cells is typically associated with increased proliferation, loss of contact inhibition, acquisition of anchorage-independent ...

focus-formation-cell-based-assay-to-determine-oncogenic-potential

Research

JoVE Journal

Medicine

27.8K vistas.  University of California, Davis.  El ensayo Focus Formación ofrece un método sencillo para evaluar el potencial de transformación de un oncogén candidato. 

Video: Focus Formation: A Cell-based Assay to Determine the Oncogenic Potential of a Gene

Utilizing Functional Genomics Screening to Identify Potentially Novel Drug Targets in Cancer Cell Spheroid Cultures

The identification of functional driver events in cancer is central to furthering our understanding of cancer biology and indispensable for the discovery of the next generation of novel drug targets. It is becoming apparent that more complex models of cancer are required to fully appreciate the contributing factors that drive tumorigenesis in vivo and increase the efficacy of novel therapies that make the transition from pre-clinical models to clinical trials.
Here we present a methodology for generating uniform and reproducible tumor spheroids that can be subjected to siRNA functional screening. These spheroids display many characteristics that are found in solid tumors that are not present in traditional two-dimension culture. We show that several commonly used breast cancer cell lines are amenable to this protocol. Furthermore, we provide proof-of-principle data utilizing the breast cancer cell line BT474, confirming their dependency on amplification of the epidermal growth factor receptor HER2 and mutation of phosphatidylinositol-4,5-biphosphate 3-kinase (PIK3CA) when grown as tumor spheroids. Finally, we are able to further investigate and confirm the spatial impact of these dependencies using immunohistochemistry.

Identifying novel drug targets that transition from pre-clinical testing to human trials is a scientific priority. To that end, here we describe a functional genomics approach for examining the impact of gene depletion on cancer cell line spheroids, which more appropriately model human cancers in vivo.

La utilización de la genómica funcional de selección para identificar dianas farmacológicas potencialmente nueva en la celda cáncer culturas Esferoide

The identification of functional driver events in cancer is central to furthering our understanding of cancer biology and indispensable for the discovery ...

Investigación

Investigación sobre el cáncer

Colony Forming Cell (CFC) Assay for Human Hematopoietic Cells

Human hematopoietic stem/progenitor cells are usually obtained from bone marrow, cord blood, or peripheral blood and are used to study hematopoiesis and leukemogenesis. They have the capacity to differentiate into lymphoid and myeloid lineages. The colony forming cell (CFC) assay is used to study the proliferation and differentiation pattern of hematopoietic progenitors by their ability to form colonies in a semisolid medium. The number and the morphology of the colonies formed by a fixed number of input cells provide preliminary information about the ability of progenitors to differentiate and proliferate. Cells can be harvested from individual colonies or from the whole plate to further assess their numbers and differentiation states using flow cytometry and morphologic evaluation of Giemsa-stained slides. This assay is useful for assessing myeloid but not lymphoid differentiation. The term myeloid in this context is used in its wider sense to encompass granulocytic, monocytic, erythroid, and megakaryocytic lineages.

We have used this assay to assess the effects of oncogenes on the differentiation of primary human CD34+ cells derived from peripheral blood. For this purpose cells are transduced with either control retroviral construct or a construct expressing the oncogene of interest, in this case NUP98-HOXA9. We employ a commonly used retroviral vector, MSCV-IRES-GFP, that expresses a bicistronic mRNA that produces the gene of interest and a GFP marker. Cells are pre-activated by growing in the presence of cytokines for two days prior to retroviral transduction. After another two days, GFP+ cells are isolated by fluorescence-activated cell sorting (FACS) and mixed with a methylcellulose-containing semisolid medium supplemented with cytokines and incubated till colonies appear on the surface, typically 14 days. The number and morphology of the colonies are documented. Cells are then removed from the plates, washed, counted, and subjected to flow cytometry and morphologic examination. Flow cytometry with antibodies specific to the cell surface markers expressed during hematopoiesis provides information about lineage and maturation stage. Morphological studies of individual cells under a microscope after Wright- Giemsa staining provide further information with regard to lineage and maturation. Comparison of cells transduced with control empty vector to those transduced with an oncogene reveals the effects of the oncogene on hematopoietic differentiation.

Colony Forming Cell CFC Assay for Human Hematopoietic Cells

The colony forming cell (CFC) assay is an in vitro assay in which hematopoietic progenitors form colonies in a semi-solid medium. A combination of colony morphology, cell morphology, and flow cytometry are used to assess the ability of the progenitors to proliferate and differentiate along the different hematopoietic lineages.

La formación de colonias de células (CFC) para el ensayo de células hematopoyéticas humanas

Human hematopoietic stem/progenitor cells are usually obtained from bone marrow, cord blood, or peripheral blood and are used to study hematopoiesis and ...

Inmunología e Infección

Methods for Evaluating the Role of c-Fos and Dusp1 in Oncogene Dependence

The demonstration of tyrosine kinase inhibitors (TKIs) in treating chronic myeloid leukemia (CML) has heralded a new era in cancer therapeutics. However, a small population of cells does not respond to TKI treatment, resulting in minimal residual disease (MRD); even the most potent TKIs fail to eradicate these cells. These MRD cells serve as a reservoir to develop resistance to therapy. Why TKI treatment is ineffective against MRD cells is not known. Growth factor signaling is implicated in supporting the survival of MRD cells during TKI treatment, but a mechanistic understanding is lacking. Recent studies demonstrated that an elevated c-Fos and Dusp1 expression as a result of convergent oncogenic and growth factor signaling in MRD cells mediate TKI resistance. The genetic and chemical inhibition of c-Fos and Dusp1 renders CML exquisitely sensitive to TKIs and cures CML in both genetic and humanized mouse models. We identified these target genes using multiple microarrays from TKI-sensitive and -resistant cells. Here, we provide methods for target validation using in vitro and in vivo mouse models. These methods can easily be applied to any target for genetic validation and therapeutic development.

Here, we describe protocols for the genetic and chemical validation of c-Fos and Dusp1 as a drug target in leukemia using in vitro and in vivo genetic and humanized mouse models. This method can be applied to any target for genetic validation and therapeutic development.

Métodos para evaluar el papel de c-Fos y Dusp1 en dependencia del oncogén

The demonstration of tyrosine kinase inhibitors (TKIs) in treating chronic myeloid leukemia (CML) has heralded a new era in cancer therapeutics. However, ...

Oncogenic Gene Fusion Detection Using Anchored Multiplex Polymerase Chain Reaction Followed by Next Generation Sequencing

Gene fusions frequently contribute to the oncogenic phenotype of many different types of cancer. Additionally, the presence of certain fusions in samples from cancer patients often directly influences diagnosis, prognosis, and/or therapy selection. As a result, the accurate detection of gene fusions has become a critical component of clinical management for many disease types. Until recently, clinical gene fusion detection was predominantly accomplished through the use of single-gene assays. However, the ever-growing list of gene fusions with clinical significance has created a need for assessing fusion status of multiple genes simultaneously. Next generation sequencing (NGS)-based testing has met this demand through the ability to sequence nucleic acid in massively parallel fashion. Multiple NGS-based approaches that employ different strategies for gene target enrichment are now available for use in clinical molecular diagnostics, each with its own strengths and weaknesses. This article describes the use of anchored multiplex PCR (AMP)-based target enrichment and library preparation followed by NGS to assess for gene fusions in clinical solid tumor specimens. AMP is unique among amplicon-based enrichment approaches in that it identifies gene fusions regardless of the identity of the fusion partner. Detailed here are both the wet-bench and data analysis steps that ensure accurate gene fusion detection from clinical samples.

This article details the use of an anchored multiplex polymerase chain reaction-based library preparation kit followed by next-generation sequencing to assess for oncogenic gene fusions in clinical solid tumor samples. Both wet-bench and data analysis steps are described.

Detección de fusión genética oncogénica mediante reacción en cadena de polimerasa múltiplex anclada seguida de secuenciación de próxima generación

Gene fusions frequently contribute to the oncogenic phenotype of many different types of cancer. Additionally, the presence of certain fusions in samples ...

The Use of Mouse Mammary Tumor Cells in an In Vitro Invasion Assay as a Measure of Oncogenic Cell Behavior

The in vitro invasion assay uses a protein-rich matrix in a Boyden chamber to measure the ability of cultured cells to pass through the matrix and a porous membrane in a process analogous to the initial steps of cancer cell metastasis. The tested cells can be altered for the gene expression or treated with inhibitors to test for changes in the invasion potential. This experiment tests the aggressive phenotype of the mouse mammary tumor cells to discover and characterize the potential oncogenes that promote cell invasion. This technique, however, can be versatile and adapted to many different applications. The experiment itself can be done in one day and the results are acquired by light microscopy in less than a day. The results include counts of the number of invading cells for comparison and analysis. The in vitro invasion assay is a rapid, inexpensive, and clear-cut method for determining cell behavior in a culture that can be used as an initial assessment before more involved in vivo assays.

The in vitro cell invasion assay is used to measure the potential of cancer metastasis by quantifying the cellular potential for invasion and migration using cell culture inserts containing protein matrix. Cells are challenged to migrate through the protein matrix and a porous membrane, towards a chemoattractant, and then quantified by light microscopy.

El uso de células tumorales mamarias de ratón en un ensayo de invasión in vitro como medida del comportamiento de las células oncogénicas

The in vitro invasion assay uses a protein-rich matrix in a Boyden chamber to measure the ability of cultured cells to pass through the matrix and a ...

Genética

Tumorsphere Derivation and Treatment from Primary Tumor Cells Isolated from Mouse Rhabdomyosarcomas

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Although significant efforts have enabled the identification of common mutations associated with RMS and allowed discrimination of different RMS subtypes, major challenges still exist for the development of novel treatments to further improve prognosis. Although identified by the expression of myogenic markers, there is still significant controversy over whether RMS has myogenic or non-myogenic origins, as the cell of origin is still poorly understood. In the present study, a reliable method is provided for the tumorsphere assay for mouse RMS. The assay is based on functional properties of tumor cells and allows the identification of rare populations in the tumor with tumorigenic functions. Also described are procedures for testing recombinant proteins, integrating transfection protocols with the tumorsphere assay, and evaluating candidate genes involved in tumor development and growth. Described further is a procedure for allograft transplantation of tumorspheres into recipient mice to validate tumorigenic function in vivo. Overall, the described method allows reliable identification and testing of rare RMS tumorigenic populations that can be applied to RMS arising in different contexts. Finally, the protocol can be utilized as a platform for drug screening and future development of therapeutics.

This protocol describes a reproducible method for isolation of mouse rhabdomyosarcoma primary cells, tumorsphere formation and treatment, and allograft transplantation starting from tumorspheres cultures.

Derivación y tratamiento de tumoresferas a partir de células tumorales primarias aisladas de Rhabdomyosarcomas de ratón

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Although significant efforts have enabled the identification of common ...

Mapping the Structure-Function Relationships of Disordered Oncogenic Transcription Factors Using Transcriptomic Analysis

Many cancers are characterized by chromosomal translocations which result in the expression of oncogenic fusion transcription factors. Typically, these proteins contain an intrinsically disordered domain (IDD) fused with the DNA-binding domain (DBD) of another protein and orchestrate widespread transcriptional changes to promote malignancy. These fusions are often the sole recurring genomic aberration in the cancers they cause, making them attractive therapeutic targets. However, targeting oncogenic transcription factors requires a better understanding of the mechanistic role that low-complexity, IDDs play in their function. The N-terminal domain of EWSR1 is an IDD involved in a variety of oncogenic fusion transcription factors, including EWS/FLI, EWS/ATF, and EWS/WT1. Here, we use RNA-sequencing to investigate the structural features of the EWS domain important for transcriptional function of EWS/FLI in Ewing sarcoma. First shRNA-mediated depletion of the endogenous fusion from Ewing sarcoma cells paired with ectopic expression of a variety of EWS-mutant constructs is performed. Then RNA-sequencing is used to analyze the transcriptomes of cells expressing these constructs to characterize the functional deficits associated with mutations in the EWS domain. By integrating the transcriptomic analyses with previously published information about EWS/FLI DNA binding motifs, and genomic localization, as well as functional assays for transforming ability, we were able to identify structural features of EWS/FLI important for oncogenesis and define a novel set of EWS/FLI target genes critical for Ewing sarcoma. This paper demonstrates the use of RNA-sequencing as a method to map the structure-function relationship of the intrinsically disordered domain of oncogenic transcription factors.

Intrinsically disordered domains are important for oncogenic fusion transcription factor function. To therapeutically target these proteins, a more detailed understanding of the regulatory mechanisms employed by these domains is required. Here, we use transcriptomics to map important structural features of the intrinsically disordered EWS domain in Ewing sarcoma.

Mapeo de las relaciones estructura-función de los factores de transcripción oncogénicos desordenados utilizando el análisis transcriptómico

Many cancers are characterized by chromosomal translocations which result in the expression of oncogenic fusion transcription factors. Typically, these ...

A Multiplexed Luciferase-based Screening Platform for Interrogating Cancer-associated Signal Transduction in Cultured Cells

Genome-scale interrogation of gene function using RNA interference (RNAi) holds tremendous promise for the rapid identification of chemically tractable cancer cell vulnerabilities. Limiting the potential of this technology is the inability to rapidly delineate the mechanistic basis of phenotypic outcomes and thus inform the development of molecularly targeted therapeutic strategies. We outline here methods to deconstruct cellular phenotypes induced by RNAi-mediated gene targeting using multiplexed reporter systems that allow monitoring of key cancer cell-associated processes. This high-content screening methodology is versatile and can be readily adapted for the screening of other types of large molecular libraries.

Achieving a systems level understanding of cellular processes is a goal of modern-day cell biology. We describe here strategies for multiplexing luciferase reporters of various cellular function end-points to interrogate gene function using genome-scale RNAi libraries.

Una plataforma de detección de luciferasa basado multiplexado para interrogar cáncer asociado transducción de señales en las células cultivadas

Genome-scale interrogation of gene function using RNA interference (RNAi)  holds tremendous promise for the rapid identification of chemically tractable  ...

Medicina

The Soft Agar Colony Formation Assay

Anchorage-independent growth is the ability of transformed cells to grow independently of a solid surface, and is a hallmark of carcinogenesis. The soft agar colony formation assay is a well-established method for characterizing this capability in vitro and is considered to be one of the most stringent tests for malignant transformation in cells. This assay also allows for semi-quantitative evaluation of this capability in response to various treatment conditions. Here, we will demonstrate the soft agar colony formation assay using a murine lung carcinoma cell line, CMT167, to demonstrate the tumor suppressive effects of two members of the Wnt signaling pathway, Wnt7A and Frizzled-9 (Fzd-9). Concurrent overexpression of Wnt7a and Fzd-9 caused an inhibition of colony formation in CMT167 cells. This shows that expression of Wnt7a ligand and its Frizzled-9 receptor is sufficient to suppress tumor growth in a murine lung carcinoma model.

The soft agar colony formation assay is a method used to confirm cellular anchorage-independent growth in vitro. The goal of this protocol is to illustrate a stringent method for the detection of the tumorigenic potential of transformed cells and the tumor suppressive effects of proteins on transformed cells.

El ensayo de formación de colonias en agar blando

Anchorage-independent growth is the ability of transformed cells to grow independently of a solid surface, and is a hallmark of carcinogenesis. The soft ...

Biología

Methyl Cellulose-Based CFU Assay: A Method to Determine the Effect of Anti-cancer Compounds on Colony Formation in Leukemic Cells

Source: Kesarwani, M., et al. <a href="https://www.jove.com/t/58194">Methods for Evaluating the Role of c-Fos and Dusp1 in Oncogene Dependence.</a> J. Vis. Exp. (2019).
This video describes the protocol for methyl cellulose-based colony formation unit or CFU assay, which helps identify and count the number of colonies formed by leukemic cells in response to the treatment with anticancer compounds.

Ensayo de UFC basado en metilcelulosa: un método para determinar el efecto de los compuestos anticancerígenos en la formación de colonias en células leucémicas

Source: Kesarwani, M., et al. Methods for Evaluating the Role of c-Fos and Dusp1 in Oncogene Dependence. J. Vis. Exp. (2019).
This video describes the ...