N-Myc and GCN5 regulate significantly overlapping transcriptional programs in neural stem cells.

Here we examine the functions of the Myc cofactor and histone acetyltransferase, GCN5/KAT2A, in neural stem and precursor cells (NSC) using a conditional knockout approach driven by nestin-cre. Mice with GCN5-deficient NSC exhibit a 25% reduction in brain mass with a microcephaly phenotype similar to that observed in nestin-cre driven knockouts of c- or N-myc. In addition, the loss of GCN5 inhibits precursor cell proliferation and reduces their populations in vivo, as does loss of N-myc.

Histone-modifying enzymes: regulators of developmental decisions and drivers of human disease.

Precise transcriptional networks drive the orchestration and execution of complex developmental processes. Transcription factors possessing sequence-specific DNA binding properties activate or repress target genes in a step-wise manner to control most cell lineage decisions. This regulation often requires the interaction between transcription factors and subunits of massive protein complexes that bear enzymatic activities towards histones.

Selecting and isolating colonies of human induced pluripotent stem cells reprogrammed from adult fibroblasts.

Herein we present a protocol of reprogramming human adult fibroblasts into human induced pluripotent stem cells (hiPSC) using retroviral vectors encoding Oct3/4, Sox2, Klf4 and c-myc (OSKM) in the presence of sodium butyrate (1-3). We used this method to reprogram late passage (>p10) human adult fibroblasts derived from Friedreich's ataxia patient (GM03665, Coriell Repository). The reprogramming approach includes highly efficient transduction protocol using repetitive centrifugation of fibroblasts in the presence of virus-containing media.

Evaluating survivorship care plans: results of a randomized, clinical trial of patients with breast cancer.

Purpose: An Institute of Medicine report recommends that patients with cancer receive a survivorship care plan (SCP). The trial objective was to determine if an SCP for breast cancer survivors improves patient-reported outcomes.

Patients And Methods: Women with early-stage breast cancer who completed primary treatment at least 3 months previously were eligible.

Gcn5 loss-of-function accelerates cerebellar and retinal degeneration in a SCA7 mouse model.

Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disease caused by expansion of a CAG repeat encoding a polyglutamine tract in ATXN7, a component of the SAGA histone acetyltransferase (HAT) complex. Previous studies provided conflicting evidence regarding the effects of polyQ-ATXN7 on the activity of Gcn5, the HAT catalytic subunit of SAGA. Here, we report that reducing Gcn5 expression accelerates both cerebellar and retinal degeneration in a mouse model of SCA7.

Randomized trial of tamoxifen versus combined tamoxifen and octreotide LAR Therapy in the adjuvant treatment of early-stage breast cancer in postmenopausal women: NCIC CTG MA.14.

Purpose: Somatostatin analogs act directly on breast cancer cells and indirectly on insulin and insulin-like growth factor 1 (IGF-1) levels. This trial was undertaken to assess whether octreotide would lower insulin and IGF-1 levels and reduce risk of breast cancer recurrence.

Patients And Methods: The NCIC CTG MA.

Chromatin signaling to kinetochores: transregulation of Dam1 methylation by histone H2B ubiquitination.

Histone H3K4 trimethylation by the Set1/MLL family of proteins provides a hallmark for transcriptional activity from yeast to humans. In S. cerevisiae, H3K4 methylation is mediated by the Set1-containing COMPASS complex and is regulated in trans by prior ubiquitination of histone H2BK123.

USP22 regulates cell proliferation by deubiquitinating the transcriptional regulator FBP1.

Ubiquitin-specific protease 22 (USP22) edits the histone code by deubiquitinating H2A and H2B as part of the mammalian SAGA (Spt-Ada-Gcn5) complex, and is required for transcriptional regulation and normal cell-cycle progression. Here, we show that USP22 affects the expression of p21 by altering far upstream element (FUSE)-binding protein 1 (FBP1) ubiquitination, as ablation of USP22 leads to increased FBP1 ubiquitination and decreased FBP1 protein occupancy at the p21 gene. Surprisingly, increased polyubiquitination of FBP1 does not alter its protein stability, but instead modulates the stable recruitment of FBP1 to target loci.

Hyperexpansion of GAA repeats affects post-initiation steps of FXN transcription in Friedreich's ataxia.

Friedreich's ataxia (FRDA) is caused by biallelic expansion of GAA repeats leading to the transcriptional silencing of the frataxin (FXN) gene. The exact molecular mechanism of inhibition of FXN expression is unclear. Herein, we analyze the effects of hyperexpanded GAA repeats on transcription status and chromatin modifications proximal and distal to the GAA repeats.

Real-world experience with adjuvant fec-d chemotherapy in four Ontario regional cancer centres.

Background: The efficacy of adjuvant chemotherapy with fec-d (5-fluorouracil-epirubicin-cyclophosphamide followed by docetaxel) is superior to that with fec-100 alone in women with early-stage breast cancer. As the use of fec-d increased in clinical practice, health care providers anecdotally noted higher-than-expected toxicity rates and frequent early treatment discontinuations because of toxicity. In the present study, we compared the rates of serious adverse events in patients who received adjuvant fec-d chemotherapy in routine clinical practice with the rates reported in the pacs-01 trial.

Ubp8 and SAGA regulate Snf1 AMP kinase activity.

Posttranslational modifications of histone proteins play important roles in the modulation of gene expression. The Saccharomyces cerevisiae (yeast) 2-MDa SAGA (Spt-Ada-Gcn5) complex, a well-studied multisubunit histone modifier, regulates gene expression through Gcn5-mediated histone acetylation and Ubp8-mediated histone deubiquitination. Using a proteomics approach, we determined that the SAGA complex also deubiquitinates nonhistone proteins, including Snf1, an AMP-activated kinase.

Chromatin "prepattern" and histone modifiers in a fate choice for liver and pancreas.

Transcriptionally silent genes can be marked by histone modifications and regulatory proteins that indicate the genes' potential to be activated. Such marks have been identified in pluripotent cells, but it is unknown how such marks occur in descendant, multipotent embryonic cells that have restricted cell fate choices. We isolated mouse embryonic endoderm cells and assessed histone modifications at regulatory elements of silent genes that are activated upon liver or pancreas fate choices.

Protein-arginine methyltransferase 1 (PRMT1) methylates Ash2L, a shared component of mammalian histone H3K4 methyltransferase complexes.

Multiple enzymes and enzymatic complexes coordinately regulate the addition and removal of post-translational modifications on histone proteins. The oncoprotein Ash2L is a component of the mixed lineage leukemia (MLL) family members 1-4, Setd1A, and Setd1B mammalian histone H3K4 methyltransferase complexes and is essential to maintain global trimethylation of histone H3K4. However, regulation of these complexes at the level of expression and activity remains poorly understood.

Aromatase inhibitor therapy: toxicities and management strategies in the treatment of postmenopausal women with hormone-sensitive early breast cancer.

Aromatase inhibitors (AIs) have been shown to reduce the risk of breast cancer recurrence and are widely used today as adjuvant therapy in women with early stage endocrine-responsive breast cancer. Aromatase inhibitors may be prescribed as initial hormonal therapy, sequentially following 2-3 years of tamoxifen, or as extended adjuvant therapy (following 5 years of tamoxifen). Aromatase inhibitors are generally well tolerated; however, certain side effects, particularly arthralgia/musculoskeletal symptoms and gynecologic effects, may result in poor adherence to treatment.

Distinct roles of GCN5/PCAF-mediated H3K9ac and CBP/p300-mediated H3K18/27ac in nuclear receptor transactivation.

Histone acetyltransferases (HATs) GCN5 and PCAF (GCN5/PCAF) and CBP and p300 (CBP/p300) are transcription co-activators. However, how these two distinct families of HATs regulate gene activation remains unclear. Here, we show deletion of GCN5/PCAF in cells specifically and dramatically reduces acetylation on histone H3K9 (H3K9ac) while deletion of CBP/p300 specifically and dramatically reduces acetylations on H3K18 and H3K27 (H3K18/27ac).

Acquisition of metastatic tissue from patients with bone metastases from breast cancer.

Biopsies of metastatic tissue are increasingly being performed. Bone is the most frequent site of metastasis in breast cancer patients, but bone remains technically challenging to biopsy. Difficulties with both tissue acquisition and techniques for analysis of hormone receptor status are well described.

Endocrine therapy for male breast cancer: rates of toxicity and adherence.

Purpose: Most male breast cancer tumours are hormone receptor-positive; the patients therefore receive endocrine therapy. There is, however, a paucity of published data on toxicities experienced by male breast cancer patients who are prescribed endocrine therapy. In the present study, we examined rates of adherence to and toxicity from endocrine treatments in male breast cancer patients treated at a single institution.

The role of deubiquitinating enzymes in chromatin regulation.

Post-translational modifications of the histones are centrally involved in the regulation of all DNA-templated processes, including gene transcription, DNA replication, recombination, and repair. These modifications are often dynamic, and their removal is just as important as their addition in proper regulation of cellular functions. Although histone acetylation/deacetylation and histone methylation/demethylation are highly studied, the functions and regulation of histone ubiquitination and deubiquitination are less well understood.

Optimizing the management of HER2-positive early breast cancer: the clinical reality.

Breast cancer positive for HER2 (human epidermal growth factor receptor 2) is associated with a poor prognosis for patients with both early-stage and metastatic breast cancer. Trastuzumab has been shown to be effective and is now considered the standard of care for early-stage patients with HER2-positive breast cancer. In that population, trastuzumab has been studied in six randomized clinical trials.

A phase II study of pazopanib in patients with recurrent or metastatic invasive breast carcinoma: a trial of the Princess Margaret Hospital phase II consortium.

Purpose: Angiogenesis is an important hallmark of breast cancer growth and progression. Pazopanib, an oral small molecule inhibitor of vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and KIT, has activity across a range of solid tumors. We evaluated the activity of single-agent pazopanib in recurrent or metastatic breast cancer (MBC).

Multiple faces of the SAGA complex.

The SAGA complex provides a paradigm for multisubunit histone modifying complexes. Although first characterized as a histone acetyltransferase, because of the Gcn5 subunit, SAGA is now known to contain a second activity, a histone deubiquitinase, as well as subunits important for interactions with transcriptional activators and the general transcription machinery. The functions of SAGA in transcriptional activation are well-established in Saccharomyces cerevisiae.

R loops stimulate genetic instability of CTG.CAG repeats.

Transcription stimulates the genetic instability of trinucleotide repeat sequences. However, the mechanisms leading to transcription-dependent repeat length variation are unclear. We demonstrate, using biochemical and genetic approaches, that the formation of stable RNA.

Phase I/II trial of metronomic chemotherapy with daily dalteparin and cyclophosphamide, twice-weekly methotrexate, and daily prednisone as therapy for metastatic breast cancer using vascular endothelial growth factor and soluble vascular endothelial growth factor receptor levels as markers of response.

PURPOSE Preclinical studies indicate that metronomic chemotherapy is antiangiogenic and synergistic with other antiangiogenic agents. We designed a phase I/II study to evaluate the safety and activity of adding dalteparin and prednisone to metronomic cyclophosphamide and methotrexate in women with measurable metastatic breast cancer (MBC). PATIENTS AND METHODS Patients received daily dalteparin and oral cyclophosphamide, twice-weekly methotrexate, and daily prednisone (dalCMP).

Regulation of the osteoblast-specific transcription factor Osterix by NO66, a Jumonji family histone demethylase.

Osterix (Osx) is an osteoblast-specific transcription factor required for osteoblast differentiation and bone formation. Osx null mice develop a normal cartilage skeleton but fail to form bone and to express osteoblast-specific marker genes. To better understand the control of transcriptional regulation by Osx, we identified Osx-interacting proteins using proteomics approaches.

The role of neoadjuvant (HER)2-targeted therapies in (HER)2-overexpressing breast cancers.

Women receiving neoadjuvant systemic therapy for primary operable or inoperable breast cancer can potentially benefit in a number of ways, but the main advantage, which has been consistently demonstrated, is improved tumour resectability. Given the improvement in outcomes with the adjuvant use of trastuzumab in patients with early-stage breast cancer positive for the human epidermal growth factor receptor 2 (HER2), questions have been raised about the use of trastuzumab in the neoadjuvant setting. The present paper reviews the currently available data and outlines suggestions from a panel of Canadian oncologists about the use of trastuzumab and other HER2-targeted agents in the neoadjuvant setting.