6 research outputs found
Efecto del 谩cido retinoico sobre la apoptosis, proliferaci贸n y migraci贸n de c茅lulas de c谩ncer de pulm贸n, a trav茅s de las v铆as PI3K-Akt y MAPK
El ATRA ha sido utilizado como agente anti-neopl谩sico por su capacidad de inducir diferenciaci贸n, principalmente en leucemias, mientras que en otros tipos de c谩ncer es capaz de promover la inhibici贸n de la proliferaci贸n; sin embargo, en pacientes con c谩ncer de pulm贸n el efecto inhibitorio de proliferaci贸n no se puede apreciar en todos los casos y no se sabe a qu茅 se debe esta resistencia al tratamiento con ATRA. Por otro lado, las v铆as de se帽alizaci贸n PI3K-Akt y ERK se encuentran constitutivamente activas en c茅lulas cancerosas promoviendo sobrevivencia, proliferaci贸n e invasi贸n celular, sugiriendo su participaci贸n en la resistencia al tratamiento con ATRA en c谩ncer de pulm贸n. En este trabajo demostramos que el ATRA es capaz de activar a las v铆as de se帽alizaci贸n PI3K-Akt y ERK por un mecanismo independiente de la transcripci贸n y que, la activaci贸n de Akt y ERK est谩 relacionada con el mecanismo de resistencia a ATRA, provocando efectos desfavorables, ya que promueve sobrevivencia y migraci贸n en c茅lulas de c谩ncer de pulm贸n. La inhibici贸n de estas v铆as de se帽alizaci贸n restaura el efecto ben茅fico del ATRA, disminuyendo la proliferaci贸n, aumentando la apoptosis y evitando el proceso de migraci贸n celular. Por lo tanto, este trabajo propone el uso del ATRA en combinaci贸n con inhibidores de PI3K y ERK como posible tratamiento para ser evaluado en estudios cl铆nicos para que, en un futuro, pueda ser usado como terapia en pacientes con c谩ncer de pulm贸n que son resistentes al tratamiento con ATRA
The regulatory role of ELK-1 ubiquitination in cell proliferation and prostate cancer
Early stage Prostate Cancer (PC) is usually androgen-dependent and androgen ablation therapies have been used with good results in the destruction of androgen-dependent cells. However, anti-androgens are associated with systemic side effects and selection for tumour cells that survive in the absence of androgens, leading to androgen-independent PC.
ELK-1 is a member of the ETS-domain transcription factor family. In response to mitogens, ERKs phosphorylate and activate ELK-1 to stimulate the expression of Immediate Early Genes (IEGs) such as CFOS and EGR1, thereby promoting cell cycle entry and proliferation. In PC cells, ELK-1 expression is frequently up-regulated and androgen receptor (AR) was found to function as a constitutive coactivator for ELK-1, up-regulating a major subset of its target genes involved in cell proliferation and migration. Removal or inactivation of ELK-1 could therefore serve to suppress PC tumour growth.
Mono-ubiquitination modulates ELK-1 activity. De-ubiquitination of ELK-1 by USP17, a de-ubiquitinase over-expressed in multiple tumour types, increases ELK-1 target gene expression and cell proliferation, indicating that mono-ubiquitination of ELK-1 suppresses its activity (Ducker et al., 2019).
This project aims to identify the ubiquitin E3 ligase responsible for ELK-1 mono-ubiquitination and evaluate its role in PC.
Using a combination of gene knockdown experiments and ubiquitination assays, as well as an in silico gene expression analysis to identify ubiquitin E3 ligases that were significantly down-regulated in PC cells, I have tested candidates including FBXW7, FBXO25, SPOP and UBR5, for their ability to modify ELK-1 and suppress its activity. Moreover, using the BioID screening I was able to identify ELK-1 partners under starved and mitogen-stimulated conditions.
My findings suggest that an ubiquitin E3 ligase previously reported to target ELK-1 is unlikely to promote ELK-1 ubiquitination and transactivation. Furthermore, the BioID analysis found some potential E3 ligase candidates that need to be evaluated to elucidate their role in promoting ELK-1 ubiquitination. Additionally, the BioID analysis concluded that ELK-1 interacts with transcriptional regulators to modulate ELK-1 target genes expression
ELK-1 ubiquitination status and transcriptional activity are modulated independently of F-Box protein FBXO25
The mitogen-responsive, ETS-domain transcription factor ELK-1 stimulates the expression of immediate early genes at the onset of the cell cycle and participates in early developmental programming. ELK-1 is subject to multiple levels of posttranslational control, including phosphorylation, SUMOylation, and ubiquitination. Recently, removal of monoubiquitin from the ELK-1 ETS domain by the Ubiquitin Specific Protease USP17 was shown to augment ELK-1 transcriptional activity and promote cell proliferation. Here we have used coimmunoprecipitation experiments, protein turnover and ubiquitination assays, RNA-interference and gene expression analyses to examine the possibility that USP17 acts antagonistically with the F-box protein FBXO25, an E3 ubiquitin ligase previously shown to promote ELK-1 ubiquitination and degradation. Our data confirm that FBXO25 and ELK-1 interact in HEK293T cells and that FBXO25 is active toward Hand1 and HAX1, two of its other candidate substrates. However, our data indicate that FBXO25 neither promotes ubiquitination of ELK-1 nor impacts on its transcriptional activity and suggest that an E3 ubiquitin ligase other than FBXO25 regulates ELK-1 ubiquitination and function
EFECTO DEL ACIDO RETINOICO SOBRE LA APOPTOSIS, PROLIFERACION Y MIGRACION DE CELULAS DE CANCER DE PULMON, A TRAVES DE LAS VIAS PI3K-AKT Y MAPK
The regulatory role of ELK-1 ubiquitination in cell proliferation and prostate cancer
Early stage Prostate Cancer (PC) is usually androgen-dependent and androgen ablation therapies have been used with good results in the destruction of androgen-dependent cells. However, anti-androgens are associated with systemic side effects and selection for tumour cells that survive in the absence of androgens, leading to androgen-independent PC.
ELK-1 is a member of the ETS-domain transcription factor family. In response to mitogens, ERKs phosphorylate and activate ELK-1 to stimulate the expression of Immediate Early Genes (IEGs) such as CFOS and EGR1, thereby promoting cell cycle entry and proliferation. In PC cells, ELK-1 expression is frequently up-regulated and androgen receptor (AR) was found to function as a constitutive coactivator for ELK-1, up-regulating a major subset of its target genes involved in cell proliferation and migration. Removal or inactivation of ELK-1 could therefore serve to suppress PC tumour growth.
Mono-ubiquitination modulates ELK-1 activity. De-ubiquitination of ELK-1 by USP17, a de-ubiquitinase over-expressed in multiple tumour types, increases ELK-1 target gene expression and cell proliferation, indicating that mono-ubiquitination of ELK-1 suppresses its activity (Ducker et al., 2019).
This project aims to identify the ubiquitin E3 ligase responsible for ELK-1 mono-ubiquitination and evaluate its role in PC.
Using a combination of gene knockdown experiments and ubiquitination assays, as well as an in silico gene expression analysis to identify ubiquitin E3 ligases that were significantly down-regulated in PC cells, I have tested candidates including FBXW7, FBXO25, SPOP and UBR5, for their ability to modify ELK-1 and suppress its activity. Moreover, using the BioID screening I was able to identify ELK-1 partners under starved and mitogen-stimulated conditions.
My findings suggest that an ubiquitin E3 ligase previously reported to target ELK-1 is unlikely to promote ELK-1 ubiquitination and transactivation. Furthermore, the BioID analysis found some potential E3 ligase candidates that need to be evaluated to elucidate their role in promoting ELK-1 ubiquitination. Additionally, the BioID analysis concluded that ELK-1 interacts with transcriptional regulators to modulate ELK-1 target genes expression