In Drosophila, dosage compensation is controlled by the male-specific lethal (MSL) complex consisting of MSL proteins and roX RNAs. The MSL complex is specifically localized on the male X chromosome to increase its expression approximately 2-fold. We recently proposed a model for the targeted assembly of the MSL complex, in which initial binding occurs at approximately 35 dispersed chromatin entry sites, followed by spreading in cis into flanking regions. Here, we analyze one of the chromatin entry sites, the roX1 gene, to determine which sequences are sufficient to recruit the MSL complex. We found association and spreading of the MSL complex from roX1 transgenes in the absence of detectable roX1 RNA synthesis from the transgene. We mapped the recruitment activity to a 217 bp roX1 fragment that shows male-specific DNase hypersensitivity and can be preferentially cross-linked in vivo to the MSL complex. When inserted on autosomes, this small roX1 segment is sufficient to produce an ectopic chromatin entry site that can nucleate binding and spreading of the MSL complex hundreds of kilobases into neighboring regions.

Highlights d NF1 is a GAP-independent estrogen receptor transcription co-repressor d Somatic NF1 loss causes tamoxifen/aromatase inhibitor resistance in ER + breast cancer d A MEK inhibitor plus a SERD is effective in NF1 -ER + PDX and cell line models

Introduction:A Cochrane review of seven randomised trials (N=1571) comparing surgery and primary endocrine therapy (PET) (oestrogen receptor (ER) unselected) shows no difference in overall survival (OS). We report outcome of a large series with ER-positive (ER+) early invasive primary breast cancer.Methods:Between 1973 and 2009, 1065 older (⩾70 years) women (median age 78 years (70–99)) had either surgery (N=449) or PET (N=616) as initial treatment.Results:At 49-month median follow-up (longest 230 months), the 5-year breast cancer-specific survival (BCSS) and OS were 90 and 62%, respectively. Majority (74.2%) died from causes other than breast cancer. The rates (per annum) of local/regional recurrence (<1%) (following surgery), contralateral tumour (<1%) and metastases (<3%) were low. For patients on PET, 97.9% achieved clinical benefit (CB) at 6 months, with median time to progression of 49 months (longest 132 months) and significantly longer BCSS when compared with those who progressed (P<0.001). All patients with strongly ER+ (H-score >250) tumours achieved CB and had better BCSS (P<0.01). Patients with tumours having an H-score >250 were found to have equivalent BCSS regardless of treatment (surgery or PET; P=0.175), whereas for those with H-score ⩽250, surgery produced better outcome (P<0.001).Conclusion:Older women with ER+ breast cancer appear to have excellent long-term outcome regardless of initial treatment. Majority also die from non-breast cancer causes. Although surgery remains the treatment of choice, patients with ER-rich (H-score >250) tumours tend to do equally well when treated by PET. This should be taken into account when therapies are considered.

In the recent decade, while surgery became the predominant treatment, a significant proportion of patients had non-operative therapies, selection of which was based on multidisciplinary assessment in the clinic. This management approach appears to produce excellent clinical outcome, which is significantly better than that in earlier period.

Background Ductal carcinoma in situ (DCIS) is the most common type of in situ premalignant breast cancers. What drives DCIS to invasive breast cancer is unclear. Basal-like invasive breast cancers are aggressive. We have previously shown that NRAS is highly expressed selectively in basal-like subtypes of invasive breast cancers and can promote their growth and progression. In this study, we investigated whether NRAS expression at the DCIS stage can control transition from luminal DCIS to basal-like invasive breast cancers. Methods Wilcoxon rank-sum test was performed to assess expression of NRAS in DCIS compared to invasive breast tumors in patients. NRAS mRNA levels were also determined by fluorescence in situ hybridization in patient tumor microarrays (TMAs) with concurrent normal, DCIS, and invasive breast cancer, and association of NRAS mRNA levels with DCIS and invasive breast cancer was assessed by paired Wilcoxon signed-rank test. Pearson’s correlation was calculated between NRAS mRNA levels and basal biomarkers in the TMAs, as well as in patient datasets. RNA-seq data were generated in cell lines, and unsupervised hierarchical clustering was performed after combining with RNA-seq data from a previously published patient cohort. Results Invasive breast cancers showed higher NRAS mRNA levels compared to DCIS samples. These NRAShigh lesions were also enriched with basal-like features, such as basal gene expression signatures, lower ER, and higher p53 protein and Ki67 levels. We have shown previously that NRAS drives aggressive features in DCIS-like and basal-like SUM102PT cells. Here, we found that NRAS-silencing induced a shift to a luminal gene expression pattern. Conversely, NRAS overexpression in the luminal DCIS SUM225 cells induced a basal-like gene expression pattern, as well as an epithelial-to-mesenchymal transition signature. Furthermore, these cells formed disorganized mammospheres containing cell masses with an apparent reduction in adhesion. Conclusions These data suggest that elevated NRAS levels in DCIS are not only a marker but can also control the emergence of basal-like features leading to more aggressive tumor activity, thus supporting the therapeutic hypothesis that targeting NRAS and/or downstream pathways may block disease progression for a subset of DCIS patients with high NRAS.

No abstract

Background and Objectives Activation of ghrelin receptor growth hormone secretagogue receptor (GHS-R) by endogenous or synthetic ligands amplifies pulsatile release of growth hormone (GH) and enhances food intake, very relevant to development and growth. GHS-R is a G-protein coupled receptor that has great druggable potential. Understanding the precise ligand and receptor interactions is crucial to advance the application of GHS-R. Materials and Methods We used radiolabeled ligand-binding assay and growth hormone release assay to assess the binding and functional characteristics of GHS-R to synthetic agonists MK-0677 and GHS-25, as well as to endogenous peptide ligand ghrelin. We analyzed the ligand-dependent activity of GHS-R by measuring aequorin-based [Ca++]i responses. To define a ligand-binding pocket of GHS-R, we generated a series of human/puffer fish GHS-R chimeras by domain swapping, as well as a series of mutants by site-directed mutagenesis. Results We found that the synthetic ligands have high binding affinity to GHS-R in the in vitro competitive binding assay. Remarkably, the in vivo GH secretagogue activity is higher with the synthetic agonists MK-0677 and GHS-25 than that of ghrelin. Importantly, the activity was completely abolished in GHS-R knockout mice. In GHS-R chimera analysis, we identified the C-terminal region, particularly the transmembrane domain 6 (TM6), to be critical for the ligand-dependent activity. Our site-directed mutagenesis study further revealed that amino acid residues D99 and W276 in GHS-R are essential for ligand binding. Interestingly, critical residues distinctively interact with different ligands, MK-0677 activation depends on E124, while ghrelin and GHS-25 preferentially interact with F279. Conclusion The ligand-binding pocket of human GHS-R is mainly defined by interactive residues in TM6 and the adjacent region of the receptor. This novel finding in GHS-R binding domains advances the structural/ functional understanding of GHS-R, which will help to select/design better GHS-R agonists/ antagonists for future therapeutic applications.

No abstract