RESUMO
BACKGROUND: Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma in children. The Hedgehog (HH) pathway is known to develop an oncogenic role in RMS. However, the molecular mechanism that drives activation of the pathway in RMS is not well understood. METHODS: The expression of HH ligands was studied by qPCR, western blot and immunohistochemistry. Functional and animal model studies were carried out with cells transduced with shRNAs against HH ligands or treated with HH-specific inhibitors (Vismodegib and MEDI-5304). Finally, the molecular characterisation of an off-target effect of Vismodegib was also made. RESULTS: The results showed a prominent expression of HH ligands supporting an autocrine ligand-dependent activation of the pathway. A comparison of pharmacologic Smoothened inhibition (Vismodegib) and HH ligand blocking (MEDI-5304) is also provided. Interestingly, a first description of pernicious off-target effect of Vismodegib is also reported. CONCLUSIONS: The clarification of the HH pathway activation mechanism in RMS opens a door for targeted therapies against HH ligands as a possible alternative in the future development of better treatment protocols. Moreover, the description of a pernicious off-target effect of Vismodegib, via unfolded protein response activation, may mechanistically explain its previously reported inefficiency in several ligand-dependent cancers.
Assuntos
Carcinogênese/patologia , Proliferação de Células , Proteínas Hedgehog/metabolismo , Rabdomiossarcoma/patologia , Fatores de Transcrição/metabolismo , Animais , Apoptose , Carcinogênese/genética , Carcinogênese/metabolismo , Movimento Celular , Feminino , Proteínas Hedgehog/genética , Humanos , Ligantes , Camundongos , Camundongos SCID , Rabdomiossarcoma/genética , Rabdomiossarcoma/metabolismo , Transdução de Sinais , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The use of preclinical models is essential in translational cancer research and especially important in pediatric cancer given the low incidence of each particular type of cancer. Cell line cultures have led to significant advances in cancer biology. However, cell lines have adapted to growth in artificial culture conditions, thereby undergoing genetic and phenotypic changes which may hinder the translational application. Tumor grafts developed in mice from patient tumor tissues, generally known as patient-derived xenografts (PDXs), are interesting alternative approaches to reproducing the biology of the original tumor. This review is focused on highlighting the interest of PDX models in pediatric cancer research and supporting strategies of personalized medicine. This review provides: (1) a description of the background of PDX in cancer, (2) the particular case of PDX in pediatric cancer, (3) how PDX can improve personalized medicine strategies, (4) new methods to increase engraftment, and, finally, (5) concluding remarks.
Assuntos
Antineoplásicos/farmacologia , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Medicina de Precisão , Ensaios Antitumorais Modelo de Xenoenxerto , Animais , Humanos , Camundongos , Neoplasias/genética , Pesquisa Translacional BiomédicaRESUMO
Neuroblastoma (NB) is a neoplasm of the sympathetic nervous system, and is the most common solid tumor of infancy. NBs are very heterogeneous, with a clinical course ranging from spontaneous regression to resistance to all current forms of treatment. High-risk patients need intense chemotherapy, and only 30-40% will be cured. Relapsed or metastatic tumors acquire multi-drug resistance, raising the need for alternative treatments. Owing to the diverse mechanisms that are responsible of NB chemoresistance, we aimed to target epigenetic factors that control multiple pathways to bypass therapy resistance. We found that the SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4 (SMARCA4/BRG1) was consistently upregulated in advanced stages of NB, with high BRG1 levels being indicative of poor outcome. Loss-of-function experiments in vitro and in vivo showed that BRG1 is essential for the proliferation of NB cells. Furthermore, whole-genome transcriptome analysis revealed that BRG1 controls the expression of key elements of oncogenic pathways such as PI3K/AKT and BCL2, which offers a promising new combination therapy for high-risk NB.
Assuntos
Sobrevivência Celular/genética , DNA Helicases/genética , Neuroblastoma/genética , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Transcriptoma/genética , Morte Celular/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Neuroblastoma/patologia , Fosfatidilinositol 3-Quinases/genética , Proteínas Proto-Oncogênicas c-bcl-2/genética , Transdução de Sinais/genéticaRESUMO
BACKGROUND: Rhabdomyosarcoma (RMS) is the commonest type of soft-tissue sarcoma in children. Patients with metastatic RMS continue to have very poor prognosis. Recently, several works have demonstrated a connection between Notch pathway activation and the regulation of cell motility and invasiveness. However, the molecular mechanisms of this possible relationship remain unclear. METHODS: The Notch pathway was manipulated pharmacologically and genetically. The mRNA changes were analysed by quantitative PCR and protein variations by western blot and immunofluorescence. Finally, the capabilities of RMS cells to adhere, heal a wound and invade were assessed in the presence of neuronal cadherin (N-cadherin)- and α9-integrin-blocking antibodies. RESULTS: Cells treated with γ-secretase inhibitor showed lower adhesion capability and downregulation of N-cadherin and α9-integrin. Genetic manipulation of the Notch pathway led to concomitant variations in N-cadherin and α9-integrin. Treatment with anti-N-cadherin-blocking antibody rendered marked inhibition of cell adhesion and motility, while anti-α9-integrin-blocking antibody exerted a remarkable effect on cell adhesion and invasiveness. CONCLUSION: Neuronal cadherin and α9-integrin are postulated as leading actors in the association between the Notch pathway and promotion of cell adhesion, motility and invasion, pointing to these proteins and the Notch pathway itself as interesting putative targets for new molecular therapies against metastases in RMS.
Assuntos
Caderinas/genética , Integrinas/genética , Receptores Notch/genética , Rabdomiossarcoma/genética , Sarcoma/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/biossíntese , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Caderinas/biossíntese , Adesão Celular/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proteínas de Homeodomínio/biossíntese , Proteínas de Homeodomínio/genética , Humanos , Integrinas/biossíntese , Invasividade Neoplásica/genética , Fenótipo , Receptores Notch/antagonistas & inibidores , Transdução de Sinais , Fatores de Transcrição HES-1 , Cicatrização/genéticaRESUMO
Recent advances in the knowledge of the molecular biology of paediatric sarcomas, especially the characterisation of chromosomal translocations associated specifically with particular types of cancer, have established bases for the introduction of new diagnostic tools. This article reviews the main chromosomal translocations associated with paediatric tumours, and summarises their molecular characteristics regarding their oncogenic capabilities, possible usefulness as a differential diagnostic tools and possible correlation with clinical parameters.