Abstract
The ERG (ETS-related gene) transcription factor is linked to various types of cancer, including leukemia. However, the specific ERG domains and co-factors contributing to leukemogenesis are ...poorly understood. Drug targeting a transcription factor such as ERG is challenging. Our study reveals the critical role of a conserved amino acid, proline, at position 199, located at the 3’ end of the PNT (pointed) domain, in ERG’s ability to induce leukemia. P199 is necessary for ERG to promote self-renewal, prevent myeloid differentiation in hematopoietic progenitor cells, and initiate leukemia in mouse models. Here we show that P199 facilitates ERG’s interaction with the NCoR-HDAC3 co-repressor complex. Inhibiting HDAC3 reduces the growth of ERG-dependent leukemic and prostate cancer cells, indicating that the interaction between ERG and the NCoR-HDAC3 co-repressor complex is crucial for its oncogenic activity. Thus, targeting this interaction may offer a potential therapeutic intervention.
Summary
Children with constitutional trisomy 21 (cT21, Down Syndrome, DS) are at a higher risk for both myeloid and B‐lymphoid leukaemias. The myeloid leukaemias are often preceded by a transient ...neonatal pre‐leukaemic syndrome, Transient Abnormal Myelopoiesis (TAM). TAM is caused by cooperation between cT21 and acquired somatic N‐terminal truncating mutations in the key haematopoietic transcription factor GATA1. These mutations, which are not leukaemogenic in the absence of cT21, are found in almost one‐third of neonates with DS. Analysis of primary human fetal liver haematopoietic cells and of human embryonic stem cells demonstrates that cT21 itself substantially alters human fetal haematopoietic development. Consequently, many haematopoietic developmental defects are observed in neonates with DS even in the absence of TAM. Although studies in mouse models have suggested a pathogenic role of deregulated expression of several chromosome 21‐encoded genes, their role in human leukaemogenesis remains unclear. As cT21 exists in all embryonic cells, the molecular basis of cT21‐associated leukaemias probably reflects a complex interaction between deregulated gene expression in haematopoietic cells and the fetal haematopoietic microenvironment in DS.
The STIL protein is essential for centriole replication and for the non-templated, de novo centriole biogenesis that is required for mammalian embryogenesis. Here we performed quantitative ...biophysical and structural analysis of the central short coiled coil domain (CCD) of STIL that is critical for its function. Using biophysical, biochemical and cell biology approaches, we identified the specific residues in the CCD that mediate the oligomerization, centrosomal localization and protein interactions of STIL. We characterized the structural properties of the coiled coil peptide using circular dichroism spectroscopy and size exclusion chromatography. We identified two regions in this domain, containing eight hydrophobic residues, which mediate the coiled coil oligomerization. Mutations in these residues destabilized the coiled coil thermodynamically but in most cases did not affect its secondary structure. Reconstituting mouse embryonic fibroblasts lacking endogenous Stil, we show that STIL oligomerization mediated by these residues is not only important for the centrosomal functions of STIL during the canonical duplication process but also for de-novo formation of centrosomes.
Hematopoietic-specific microRNA-142 is a critical regulator of various blood cell lineages, but its role in erythrocytes is unexplored. Herein, we characterize the impact of microRNA-142 on ...erythrocyte physiology and molecular cell biology, using a mouse loss-of-function allele. We report that microRNA-142 is required for maintaining the typical erythrocyte biconcave shape and structural resilience, for the normal metabolism of reactive oxygen species, and for overall lifespan. microRNA-142 further controls ACTIN filament homeostasis and membrane skeleton organization. The analyses presented reveal previously unappreciated functions of microRNA-142 and contribute to an emerging view of small RNAs as key players in erythropoiesis. Finally, the work herein demonstrates how a housekeeping network of cytoskeletal regulators can be reshaped by a single micro-RNA denominator in a cell type specific manner.
Purpose: Brain metastases affect 25% of patients with non–small cell lung cancer (NSCLC). We hypothesized that the expression of genes
in primary NSCLC tumors could predict brain metastasis and be ...used for identification of high-risk patients, who may benefit
from prophylactic therapy.
Experimental Design: The expression of 12 genes was measured by real-time quantitative reverse transcriptase PCR in 142 frozen NSCLC tissue samples.
Univariate and multivariate Cox regression analysis was used to analyze the correlation between gene expression and the occurrence
of brain metastasis. Immunohistochemistry on independent samples was used to verify the findings.
Results: A score based on the expression levels of three genes, CDH2 (N-cadherin), KIFC1 , and FALZ , was highly predictive of brain metastasis in early and advanced lung cancer. The probability of remaining brain metastasis–free
at 2 years after diagnosis was 90.0 ± 9.5% for patients with stage I/stage II tumors and low score compared with 62.7 ± 12%
for patients with high score ( P < 0.01). In patients with more advanced lung cancer, the brain metastasis–free survival at 24 months was 89% for patients
with low score compared with only 37% in patients with high score ( P < 0.02). These results were confirmed by immunohistochemical detection of N-cadherin in independent cohort of primary NSCLC.
Conclusions: The expression levels of three genes in primary NSCLC tumors may be used to identify patients at high risk for brain metastasis
who may benefit from prophylactic therapy to the central nervous system.
ERG Is a Megakaryocytic Oncogene SALEK-ARDAKANI, Samira; SMOOHA, Gil; DE BOER, Jasper ...
Cancer research (Chicago, Ill.),
06/2009, Letnik:
69, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Ets-related gene (ERG) is a member of the ETS transcription factor gene family located on Hsa21. ERG is known to have a crucial role in establishing definitive hematopoiesis and is required for ...normal megakaryopoiesis. Truncated forms of ERG are associated with multiple cancers such as Ewing's sarcoma, prostate cancer, and leukemia as part of oncogenic fusion translocations. Increased expression of ERG is highly indicative of poor prognosis in acute myeloid leukemia and ERG is expressed in acute megakaryoblastic leukemia (AMKL); however, it is unclear if expression of ERG per se has a leukemogenic activity. We show that ectopic expression of ERG in fetal hematopoietic progenitors promotes megakaryopoiesis and that ERG alone acts as a potent oncogene in vivo leading to rapid onset of leukemia in mice. We observe that the endogenous ERG is required for the proliferation and maintenance of AMKL cell lines. ERG also strongly cooperates with the GATA1s mutated protein, found in Down syndrome AMKL, to immortalize megakaryocyte progenitors, suggesting that the additional copy of ERG in trisomy 21 may have a role in Down syndrome AMKL. These data suggest that ERG is a hematopoietic oncogene that may play a direct role in myeloid leukemia pathogenesis.
Gain-of-function somatic mutations introducing cysteines to either the extracellular or to the transmembrane domain (TMD) in interleukin-7 receptor α (IL7R) or cytokine receptor-like factor 2 (CRLF2) ...have been described in acute lymphoblastic leukemias. Here we report noncysteine in-frame mutations in IL7R and CRLF2 located in a region of the TMD closer to the cytosolic domain. Biochemical and functional assays showed that these are activating mutations conferring cytokine-independent growth of progenitor lymphoid cells in vitro and are transforming in vivo. Protein fragment complementation assays suggest that despite the absence of cysteines, the mechanism of activation is through ligand-independent dimerization. Mutagenesis experiments and ConSurf calculations suggest that the mutations stabilize the homodimeric conformation, positioning the cytosolic kinases in predefined orientation to each other, thereby inducing spontaneous receptor activation independently of external signals. Hence, type I cytokine receptors may be activated in leukemia through 2 types of transmembrane somatic dimerizing mutations.
•Two distinct regions of transmembrane somatic mutations in type I cytokine receptors IL7R and CRLF2 exist in acute lymphoblastic leukemias.•Noncysteine transmembrane mutations cause functional receptor dimerization and activation transforming pro-B cells.
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