The malignant progression of pancreatic ductal adenocarcinoma (PDAC) is accompanied by a profound desmoplasia, which forces proliferating tumor cells to metabolically adapt to this new microenvironment. We established the PDAC metabolic signature to highlight the main activated tumor metabolic pathways. Comparative transcriptomic analysis identified lipid-related metabolic pathways as being the most highly enriched in PDAC, compared with a normal pancreas. Our study revealed that lipoprotein metabolic processes, in particular cholesterol uptake, are drastically activated in the tumor. This process results in an increase in the amount of cholesterol and an overexpression of the low-density lipoprotein receptor (LDLR) in pancreatic tumor cells. These findings identify LDLR as a novel metabolic target to limit PDAC progression. Here, we demonstrate that shRNA silencing of LDLR, in pancreatic tumor cells, profoundly reduces uptake of cholesterol and alters its distribution, decreases tumor cell proliferation, and limits activation of ERK1/2 survival pathway. Moreover, blocking cholesterol uptake sensitizes cells to chemotherapeutic drugs and potentiates the effect of chemotherapy on PDAC regression. Clinically, high PDAC Ldlr expression is not restricted to a specific tumor stage but is correlated to a higher risk of disease recurrence. This study provides a precise overview of lipid metabolic pathways that are disturbed in PDAC. We also highlight the high dependence of pancreatic cancer cells upon cholesterol uptake, and identify LDLR as a promising metabolic target for combined therapy, to limit PDAC progression and disease patient relapse.is one of the deadliest cancers, rated as the fourth leading cause of cancerrelated death in the United States and Europe, with a 5-y survival rate of about 4% and a median survival of less than 6 mo (1). In the absence of early warning signs, only 15% of patients with localized PDAC can be cured by surgical resection. For the remaining patients diagnosed with late-stage pancreatic cancer with metastatic disease, the current chemotherapy with gemcitabine (GEM) is mainly palliative and remains the standard treatment despite limited benefits (5.6-mo survival) (2). Recent advances in treatment, such as combined regimens using fluorouracil, leucovorin, irinotecan, and oxaliplatin, or Nab-paclitaxel plus GEM, conferred a survival advantage compared with GEM alone (2).The low response rate to chemotherapy is a result, in part, to the presence of a dense stroma, characterized by fibrillar networks around tumoral cells that compress vasculature and limit oxygen, nutrient, and drug delivery to the cells. A fundamental feature of tumoral cells is that they undergo metabolic reprogramming in response to these environmental constraints. Advances in tumor metabolism research reveal that PDAC cells primarily rely on glucose and glutamine catabolism to fulfill bioenergetic need and provide macromolecules required for growth and proliferation (3-5). However, metabolic reprogramming is a complex...

Breast cancer stem cells (bCSCs) have been implicated in tumor progression and therapeutic resistance; however, the molecular mechanisms that define this state are unclear. We have performed two microRNA (miRNA) gain- and loss-of-function screens to identify miRNAs that regulate the choice between bCSC self-renewal and differentiation. We find that micro-RNA (miR)-600 silencing results in bCSC expansion, while its overexpression reduces bCSC self-renewal, leading to decreased in vivo tumorigenicity. miR-600 targets stearoyl desaturase 1 (SCD1), an enzyme required to produce active, lipid-modified WNT proteins. In the absence of miR-600, WNT signaling is active and promotes self-renewal, whereas overexpression of miR-600 inhibits the production of active WNT and promotes bCSC differentiation. In a series of 120 breast tumors, we found that a low level of miR-600 is correlated with active WNT signaling and a poor prognosis. These findings highlight a miR-600-centered signaling network that governs bCSC-fate decisions and influences tumor progression.

a b s t r a c tTo further characterize the molecular events supporting the tumor suppressor activity of Scrib in mammals, we aim to identify new binding partners. We isolated MCC, a recently identified binding partner for b-catenin, as a new interacting protein for Scrib. MCC interacts with both Scrib and the NHERF1/NHERF2/Ezrin complex in a PDZ-dependent manner. In T47D cells, MCC and Scrib proteins colocalize at the cell membrane and reduced expression of MCC results in impaired cell migration. By contrast to Scrib, MCC inhibits cell directed migration independently of Rac1, Cdc42 and PAK activation. Altogether, these results identify MCC as a potential scaffold protein regulating cell movement and able to bind Scrib, b-catenin and NHERF1/2.

Highlights d Murine peri-sinusoidal stromal cells co-express HSC and early B cell niche genes d HSCs and early B cells form specific interaction networks with PSS cells d Nidogen-1 is involved in pro-B cell retention in the perisinusoidal niche d Stromal cells with similar characteristics are present in human bone marrow

BackgroundInflammatory breast cancer (IBC) is an aggressive form of BC poorly defined at the molecular level. We compared the molecular portraits of 63 IBC and 134 non-IBC (nIBC) clinical samples.Methodology/FindingsGenomic imbalances of 49 IBCs and 124 nIBCs were determined using high-resolution array-comparative genomic hybridization, and mRNA expression profiles of 197 samples using whole-genome microarrays. Genomic profiles of IBCs were as heterogeneous as those of nIBCs, and globally relatively close. However, IBCs showed more frequent “complex” patterns and a higher percentage of genes with CNAs per sample. The number of altered regions was similar in both types, although some regions were altered more frequently and/or with higher amplitude in IBCs. Many genes were similarly altered in both types; however, more genes displayed recurrent amplifications in IBCs. The percentage of genes whose mRNA expression correlated with CNAs was similar in both types for the gained genes, but ∼7-fold lower in IBCs for the lost genes. Integrated analysis identified 24 potential candidate IBC-specific genes. Their combined expression accurately distinguished IBCs and nIBCS in an independent validation set, and retained an independent prognostic value in a series of 1,781 nIBCs, reinforcing the hypothesis for a link with IBC aggressiveness. Consistent with the hyperproliferative and invasive phenotype of IBC these genes are notably involved in protein translation, cell cycle, RNA processing and transcription, metabolism, and cell migration.ConclusionsOur results suggest a higher genomic instability of IBC. We established the first repertory of DNA copy number alterations in this tumor, and provided a list of genes that may contribute to its aggressiveness and represent novel therapeutic targets.

Pancreatic ductal adenocarcinoma (PDA) is a critical health issue in the field of cancer, with few therapeutic options. Evidence supports an implication of the intratumoral microenvironment (stroma) on PDA progression. However, its contribution to the role of neuroplastic changes within the pathophysiology and clinical course of PDA, through tumor recurrence and neuropathic pain, remains unknown, neglecting a putative, therapeutic window. Here, we report that the intratumoral microenvironment is a mediator of PDA-associated neural remodeling (PANR), and we highlight factors such as 'SLIT2' (an axon guidance molecule), which is expressed by cancer-associated fibroblasts (CAFs), that impact on neuroplastic changes in human PDA. We showed that 'CAF-secreted SLIT2' increases neurite outgrowth from dorsal root ganglia neurons as well as from Schwann cell migration/ proliferation by modulating N-cadherin/β-catenin signaling. Importantly, SLIT2/ROBO signaling inhibition disrupts this stromal/ neural connection. Finally, we revealed that SLIT2 expression and CAFs are correlated with neural remodeling within human and mouse PDA. All together, our data demonstrate the implication of CAFs, through the secretion of axon guidance molecule, in PANR. Furthermore, it provides rationale to investigate the disruption of the stromal/neural compartment connection with SLIT2/ROBO inhibitors for the treatment of pancreatic cancer recurrence and pain. Cell Death and Disease (2015) 6, e1592; doi:10.1038/cddis.2014.557; published online 15 January 2015Even after significant efforts from the scientific community in the past decade, pancreatic ductal adenocarcinoma (PDA) remains one of the most lethal cancers with worrying predictions.1 Median survival stagnates around 5 months, together with a 5-year survival at 5%. For 5-20% of patients treated surgically, the 5-year survival reaches 20%, with a median survival of 16 months. Metastasis onset and high prevalence of local tumor recurrence after potential curative resection influence patient's survival. A recent study revealed that the overall survival of patients with tumor recurrence was 9.3, versus 26.3 months for patients without early relapse. 2,3 Although several causes are attributed to local recurrence, reports highlight intrapancreatic nerve invasion as a predictor for recurrence 4 by playing the role of a specific niche for scattered tumoral cells. In light of such epidemiologic data, there is a crucial need to develop optimal therapeutic strategies, taking into account the tumoral cellular composition, over the next decade.

One of the earliest events in epithelial carcinogenesis is the dissolution of tight junctions and cell polarity signals that are essential for normal epithelial barrier function. Here, we report that EFA6B, a guanine nucleotide exchange factor for the Ras superfamily protein Arf6 that helps assemble and stabilize tight junction, is required to maintain apico-basal cell polarity and mesenchymal phenotypes in mammary epithelial cells. In organotypic three-dimensional cell cultures, endogenous levels of EFA6B were critical to determine epithelial-mesenchymal status. EFA6B downregulation correlated with a mesenchymal phenotype and ectopic expression of EFA6B hampered TGFb-induced epithelial-to-mesenchymal transition (EMT). Transcriptomic and immunohistochemical analyses of human breast tumors revealed that the reduced expression of EFA6B was associated with loss of tight junction components and with increased signatures of EMT, cancer stemness, and poor prognosis. Accordingly, tumors with low levels of EFA6B were enriched in the aggressive triple-negative and claudin-low breast cancer subtypes. Our results identify EFA6B as a novel antagonist in breast cancer and they point to its regulatory and signaling pathways as rational therapeutic targets in aggressive forms of this disease.

Natural-killer (NK) cells are important immune effectors during a viral infection. Latent CMV infection is widely spread and was demonstrated to shape the NK cell repertoire through the NKG2C receptor. An expansion of NKG2C+ NK cells has been reported during primary HIV infection (PHI), but their role is not known. We previously found a correlation between the maturation state of the NK cell compartment and a lower viral load by studying patients from the ANRS 147 Optiprim trial. We investigated here extensively the NKG2C+ NK cells at the time of PHI and its evolution after 3 months of early antiretroviral therapy (combination antiretroviral therapy (cART)). Multiparametric cytometry combined with bioinformatics was used to determine subsets. NKbright NKG2C+ progenitor, NKdim NKG2C+ effector and NKdim NKG2C+CD57+ memory-like populations were identified. Two groups of patients were unraveled according to the distribution of the NKG2C+ subsets skewed toward either progenitor/effector or memory-like phenotype. Patients with high NKG2C+CD57+ NK cell frequencies showed lower HIV-RNA, lower immune activation, higher pDC counts and reached more rapidly undetectable levels of HIV-RNA at M1 under cART. NKG2C+CD57+ NK cell frequency was the only factor strongly correlated to low viral load among other clinical features. While the patients were cytomegalovirus (CMV) infected, there was no sign of reactivation of CMV during PHI suggesting that memory-like NK cells were already present at the time of HIV infection and constituted a preexisting immune response able to contribute to natural control of HIV. This parameter appears to be a good candidate in the search of predictive markers to monitor HIV remission.