RESUMEN
Hematopoietic insufficiency is the hallmark of acute myeloid leukemia (AML) and predisposes patients to life-threatening complications such as bleeding and infections. Addressing the contribution of mesenchymal stromal cells (MSC) to AML-induced hematopoietic failure we show that MSC from AML patients (n=64) exhibit significant growth deficiency and impaired osteogenic differentiation capacity. This was molecularly reflected by a specific methylation signature affecting pathways involved in cell differentiation, proliferation and skeletal development. In addition, we found distinct alterations of hematopoiesis-regulating factors such as Kit-ligand and Jagged1 accompanied by a significantly diminished ability to support CD34+ hematopoietic stem and progenitor cells in long-term culture-initiating cells (LTC-ICs) assays. This deficient osteogenic differentiation and insufficient stromal support was reversible and correlated with disease status as indicated by Osteocalcin serum levels and LTC-IC frequencies returning to normal values at remission. In line with this, cultivation of healthy MSC in conditioned medium from four AML cell lines resulted in decreased proliferation and osteogenic differentiation. Taken together, AML-derived MSC are molecularly and functionally altered and contribute to hematopoietic insufficiency. Inverse correlation with disease status and adoption of an AML-like phenotype after exposure to leukemic conditions suggests an instructive role of leukemic cells on bone marrow microenvironment.
Asunto(s)
Regulación Leucémica de la Expresión Génica , Leucemia Mieloide Aguda/genética , Células Madre Mesenquimatosas/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Antígenos CD34/genética , Antígenos CD34/metabolismo , Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Estudios de Casos y Controles , Diferenciación Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Medios de Cultivo Condicionados/farmacología , Femenino , Hematopoyesis/genética , Humanos , Péptidos y Proteínas de Señalización Intercelular/genética , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Proteína Jagged-1 , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patología , Masculino , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/patología , Persona de Mediana Edad , Osteocalcina/genética , Osteocalcina/metabolismo , Osteogénesis/efectos de los fármacos , Fenotipo , Proteínas Serrate-Jagged , Transducción de Señal , Factor de Células Madre/genética , Factor de Células Madre/metabolismoRESUMEN
Disruption of the histone modification patterns is one of the most common features of human tumors. However, few genetic alterations in the histone modifier genes have been described in tumorigenesis. Herein we show that the histone methyltransferase SETDB1 undergoes gene amplification in non-small and small lung cancer cell lines and primary tumors. The existence of additional copies of the SETDB1 gene in these transformed cells is associated with higher levels of the corresponding mRNA and protein. From a functional standpoint, the depletion of SETDB1 expression in amplified cells reduces cancer growth in cell culture and nude mice models, whereas its overexpression increases the tumor invasiveness. The increased gene dosage of SETDB1 is also associated with enhanced sensitivity to the growth inhibitory effect mediated by the SETDB1-interfering drug mithramycin. Overall, the findings identify SETDB1 as a bona fide oncogene undergoing gene amplification-associated activation in lung cancer and suggest its potential for new therapeutic strategies.
Asunto(s)
Adenocarcinoma/genética , Carcinoma de Células Escamosas/genética , Amplificación de Genes , Neoplasias Pulmonares/genética , Proteína Metiltransferasas/genética , Adenocarcinoma/enzimología , Adenocarcinoma/patología , Animales , Carcinogénesis/genética , Carcinoma de Células Escamosas/enzimología , Carcinoma de Células Escamosas/patología , Línea Celular Tumoral , Dosificación de Gen , N-Metiltransferasa de Histona-Lisina , Humanos , Neoplasias Pulmonares/enzimología , Neoplasias Pulmonares/patología , Ratones , Ratones Desnudos , Invasividad Neoplásica , Trasplante de Neoplasias , Proteína Metiltransferasas/metabolismoRESUMEN
CHD8 is a chromatin remodeling ATPase of the SNF2 family. We found that depletion of CHD8 impairs cell proliferation. In order to identify CHD8 target genes, we performed a transcriptomic analysis of CHD8-depleted cells, finding out that CHD8 controls the expression of cyclin E2 (CCNE2) and thymidylate synthetase (TYMS), two genes expressed in the G1/S transition of the cell cycle. CHD8 was also able to co-activate the CCNE2 promoter in transient transfection experiments. Chromatin immunoprecipitation experiments demonstrated that CHD8 binds directly to the 5' region of both CCNE2 and TYMS genes. Interestingly, both RNA polymerase II (RNAPII) and CHD8 bind constitutively to the 5' promoter-proximal region of CCNE2, regardless of the cell-cycle phase and, therefore, of the expression of CCNE2. The tandem chromodomains of CHD8 bind in vitro specifically to histone H3 di-methylated at lysine 4. However, CHD8 depletion does not affect the methylation levels of this residue. We also show that CHD8 associates with the elongating form of RNAPII, which is phosphorylated in its carboxy-terminal domain (CTD). Furthermore, CHD8-depleted cells are hypersensitive to drugs that inhibit RNAPII phosphorylation at serine 2, suggesting that CHD8 is required for an early step of the RNAPII transcription cycle.