BackgroundThe T-cell inhibitory molecule PD-L1 (B7-H1, CD274) is expressed on tumor cells of a subset of breast cancer patients. However, the mechanism that regulates PD-L1 expression in this group of patients is still not well-identified.MethodsWe have used loss and gain of function gene manipulation approach, multi-parametric flow cytometry, large scale gene expression dataset analysis and immunohistochemistry of breast cancer tissue sections.ResultsInduction of epithelial to mesenchymal transition (EMT) in human mammary epithelial cells upregulated PD-L1 expression, which was dependent mainly on the activation of the PI3K/AKT pathway. Interestingly, gene expression signatures available from large cohort of breast tumors showed a significant correlation between EMT score and the PD-L1 mRNA level (p < 0.001). Strikingly, very strong association (p < 0.0001) was found between PD-L1 expression and claudin-low subset of breast cancer, which is known to have high EMT score. On the protein level, significant correlation was found between PD-L1 expression and standard markers of EMT (p = 0.005) in 67 breast cancer patients. Importantly, specific downregulation of PD-L1 in claudin-low breast cancer cells showed signs of EMT reversal as manifested by CD44 and Vimentin downregulation and CD24 upregulation.ConclusionsWe have demonstrated a bidirectional effect between EMT status and PD-L1 expression especially in claudin-low subtype of breast cancer cells. Our findings highlights the potential dual benefit of anti-PD-L1 particularly in this subset of breast cancer patients that will likely benefit more from anti-PD-L1 targeted therapy as well as in monitoring biological changes upon treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-015-0421-2) contains supplementary material, which is available to authorized users.

Hypogonadism, alopecia, diabetes mellitus, mental retardation, and extrapyramidal syndrome (also referenced as Woodhouse-Sakati syndrome) is a rare autosomal recessive multisystemic disorder. We have identified a founder mutation consisting of a single base-pair deletion in C2orf37 in eight families of Saudi origin. Three other loss-of-function mutations were subsequently discovered in patients of different ethnicities. The gene encodes a nucleolar protein of unknown function, and the cellular phenotype observed in patient lymphoblasts implicates a role for the nucleolus in the pathogenesis of this disease. Our findings expand the list of human disorders linked to the nucleolus and further highlight the developmental and/or maintenance functions of this organelle.

MERTK is an essential component of the signaling network that controls phagocytosis in retinal pigment epithelium (RPE), the loss of which results in photoreceptor degeneration. Previous proof-of-concept studies have demonstrated the efficacy of gene therapy using human MERTK (hMERTK) packaged into adeno-associated virus (AAV2) in treating RCS rats and mice with MERTK deficiency. The purpose of this study was to assess the safety of gene transfer via subretinal administration of rAAV2-VMD2-hMERTK in subjects with MERTK-associated retinitis pigmentosa (RP). After a preclinical phase confirming the safety of the study vector in monkeys, six patients (aged 14 to 54, mean 33.3 years) with MERTK-related RP and baseline visual acuity (VA) ranging from 20/50 to <20/6400 were entered in a phase I open-label, dose-escalation trial. One eye of each patient (the worse-seeing eye in five subjects) received a submacular injection of the viral vector, first at a dose of 150 µl (5.96 × 10(10)vg; 2 patients) and then 450 µl (17.88 × 10(10)vg; 4 patients). Patients were followed daily for 10 days at 30, 60, 90, 180, 270, 365, 540, and 730 days post-injection. Collected data included (1) full ophthalmologic examination including best-corrected VA, intraocular pressure, color fundus photographs, macular spectral domain optical coherence tomography and full-field stimulus threshold test (FST) in both the study and fellow eyes; (2) systemic safety data including CBC, liver and kidney function tests, coagulation profiles, urine analysis, AAV antibody titers, peripheral blood PCR and ASR measurement; and (3) listing of ophthalmological or systemic adverse effects. All patients completed the 2-year follow-up. Subretinal injection of rAAV2-VMD2-hMERTK was associated with acceptable ocular and systemic safety profiles based on 2-year follow-up. None of the patients developed complications that could be attributed to the gene vector with certainty. Postoperatively, one patient developed filamentary keratitis, and two patients developed progressive cataract. Of these two patients, one also developed transient subfoveal fluid after the injection as well as monocular oscillopsia. Two patients developed a rise in AAV antibodies, but neither patient was positive for rAAV vector genomes via PCR. Three patients also displayed measurable improved visual acuity in the treated eye following surgery, although the improvement was lost by 2 years in two of these patients. Gene therapy for MERTK-related RP using careful subretinal injection of rAAV2-VMD2-hMERTK is not associated with major side effects and may result in clinical improvement in a subset of patients.

BACKGROUND Primordial dwarfism (PD) is an extremely rare, clinicallyheterogeneous condition characterised by profound prenatal and postnatal growth restriction among other manifestations that are helpful in the clinical classification. Recently, mutation of PCNT was reported in the context of two overlapping forms of PD: Seckel syndrome and Majewskiosteodysplastic primordial dwarfism type II (MOPDII). AIM To clinically and molecularly characterise a consanguineous family with Seckel syndrome. METHODS Clinical evaluation, linkage analysis, homozygosity mapping and mutation analysis. RESULTS Unexpectedly, linkage analysis led to the identification of a novel splice-site mutation in CENPJ that segregates with the phenotype in this family. CONCLUSION This report establishes for the first time that mutation of CENPJ can lead to Seckel syndrome and calls for further investigation of the role played by other microcephaly related genes in the pathogenesis of PD.

The expression of PD‐L1 in breast cancer is associated with estrogen receptor negativity, chemoresistance and epithelial‐to‐mesenchymal transition (EMT), all of which are common features of a highly tumorigenic subpopulation of cancer cells termed cancer stem cells (CSCs). Hitherto, the expression and intrinsic role of PD‐L1 in the dynamics of breast CSCs has not been investigated. To address this issue, we used transcriptomic datasets, proteomics and several in vitro and in vivo assays. Expression profiling of a large breast cancer dataset (530 patients) showed statistically significant correlation (p < 0.0001, r = 0.36) between PD‐L1 expression and stemness score of breast cancer. Specific knockdown of PD‐L1 using ShRNA revealed its critical role in the expression of the embryonic stem cell transcriptional factors: OCT‐4A, Nanog and the stemness factor, BMI1. Conversely, these factors could be induced upon PD‐L1 ectopic expression in cells that are normally PD‐L1 negative. Global proteomic analysis hinted for the central role of AKT in the biology of PD‐L1 expressing cells. Indeed, PD‐L1 positive effect on OCT‐4A and Nanog was dependent on AKT activation. Most importantly, downregulation of PD‐L1 compromised the self‐renewal capability of breast CSCs in vitro and in vivo as shown by tumorsphere formation assay and extreme limiting dilution assay, respectively. This study demonstrates a novel role for PD‐L1 in sustaining stemness of breast cancer cells and identifies the subpopulation and its associated molecular pathways that would be targeted upon anti‐PD‐L1 therapy.