ETS Proteins Bind with Glucocorticoid Receptors: Relevance for Treatment of Ewing Sarcoma.

The glucocorticoid receptor (GR) acts as a ubiquitous cortisol-dependent transcription factor (TF). To identify co-factors, we used protein-fragment complementation assays and found that GR recognizes FLI1 and additional ETS family proteins, TFs relaying proliferation and/or migration signals. Following steroid-dependent translocation of FLI1 and GR to the nucleus, the FLI1-specific domain (FLS) binds with GR and strongly enhances GR's transcriptional activity. This interaction has functional consequences in Ewing sarcoma (ES), childhood and adolescence bone malignancies driven by fusions between EWSR1 and FLI1. In vitro, GR knockdown inhibited the migration and proliferation of ES cells, and in animal models, antagonizing GR (or lowering cortisol) retarded both tumor growth and metastasis from bone to lung. Taken together, our findings offer mechanistic rationale for repurposing GR-targeting drugs for the treatment of patients with ES.

Phosphorylation of the phosphatase PTPROt at Tyr399 is a molecular switch that controls osteoclast activity and bone mass in vivo.

Bone resorption by osteoclasts is essential for bone homeostasis. The kinase Src promotes osteoclast activity and is activated in osteoclasts by the receptor-type tyrosine phosphatase PTPROt. In other contexts, however, PTPROt can inhibit Src activity. Through in vivo and in vitro experiments, we show that PTPROt is bifunctional and can dephosphorylate Src both at its inhibitory residue Tyr527 and its activating residue Tyr416 Whereas wild-type and PTPROt knockout mice exhibited similar bone masses, mice in which a putative C-terminal phosphorylation site, Tyr399, in endogenous PTPROt was replaced with phenylalanine had increased bone mass and reduced osteoclast activity. Osteoclasts from the knock-in mice also showed reduced Src activity. Experiments in cultured cells and in osteoclasts derived from both mouse strains demonstrated that the absence of phosphorylation at Tyr399 caused PTPROt to dephosphorylate Src at the activating site pTyr416 In contrast, phosphorylation of PTPROt at Tyr399 enabled PTPROt to recruit Src through Grb2 and to dephosphorylate Src at the inhibitory site Tyr527, thus stimulating Src activity. We conclude that reversible phosphorylation of PTPROt at Tyr399 is a molecular switch that selects between its opposing activities toward Src and maintains a coherent signaling output, and that blocking this phosphorylation event can induce physiological effects in vivo. Because most receptor-type tyrosine phosphatases contain potential phosphorylation sites at their C termini, we propose that preventing phosphorylation at these sites or its consequences may offer an alternative to inhibiting their catalytic activity to achieve therapeutic benefit.

SILAC identifies LAD1 as a filamin-binding regulator of actin dynamics in response to EGF and a marker of aggressive breast tumors.

Mutations mimicking growth factor-induced proliferation and motility characterize aggressive subtypes of mammary tumors. To unravel currently unknown players in these processes, we performed phosphoproteomic analysis on untransformed mammary epithelial cells (MCF10A) that were stimulated in culture with epidermal growth factor (EGF). We identified ladinin-1 (LAD1), a largely uncharacterized protein to date, as a phosphorylation-regulated mediator of the EGF-to-ERK pathway. Further experiments revealed that LAD1 mediated the proliferation and migration of mammary cells. LAD1 was transcriptionally induced, phosphorylated, and partly colocalized with actin stress fibers in response to EGF. Yeast two-hybrid, proximity ligation, and coimmunoprecipitation assays revealed that LAD1 bound to actin-cross-linking proteins called filamins. Cosedimentation analyses indicated that LAD1 played a role in actin dynamics, probably in collaboration with the scaffold protein 14-3-3σ (also called SFN). Depletion of LAD1 decreased the expression of transcripts associated with cell survival and inhibited the growth of mammary xenografts in an animal model. Furthermore, LAD1 predicts poor patient prognosis and is highly expressed in aggressive subtypes of breast cancer characterized as integrative clusters 5 and 10, which partly correspond to triple-negative and HER2-positive tumors. Thus, these findings reveal a cytoskeletal component that is critically involved in cell migration and the acquisition of oncogenic attributes in human mammary tumors.

An oligoclonal antibody durably overcomes resistance of lung cancer to third-generation EGFR inhibitors.

Epidermal growth factor receptor (EGFR) mutations identify patients with lung cancer who derive benefit from kinase inhibitors. However, most patients eventually develop resistance, primarily due to the T790M second-site mutation. Irreversible inhibitors (e.g., osimertinib/AZD9291) inhibit T790M-EGFR, but several mechanisms, including a third-site mutation, C797S, confer renewed resistance. We previously reported that a triple mixture of monoclonal antibodies, 3×mAbs, simultaneously targeting EGFR, HER2, and HER3, inhibits T790M-expressing tumors. We now report that 3×mAbs, including a triplet containing cetuximab and trastuzumab, inhibits C797S-expressing tumors. Unlike osimertinib, which induces apoptosis, 3×mAbs promotes degradation of the three receptors and induces cellular senescence. Consistent with distinct mechanisms, treatments combining 3×mAbs plus sub-inhibitory doses of osimertinib synergistically and persistently eliminated tumors. Thus, oligoclonal antibodies, either alone or in combination with kinase inhibitors, might preempt repeated cycles of treatment and rapid emergence of resistance.

A new role of the membrane-type matrix metalloproteinase 16 (MMP16/MT3-MMP) in neural crest cell migration.

Neural crest cells (NCCs) are a transient population of neuroectodermal-originated cells that populate the dorsal neural tube (dNT), before migrating and giving rise to multiple cell lineages in the developing embryo. Prior to their migration, NCCs undergo epithelial-to-mesenchymal-transition (EMT) through which they lose cell contacts and detach from the dNT to invade their surrounding environment. Multiple signals and transcription factors have been identified to regulate these events. Yet, less is known regarding effectors that act downstream to execute the actual NCC separation and migration. Matrix metalloproteinases (MMPs) are a family of proteases that degrade the extracellular matrix as well as other pericellular proteins during processes of tissue remodeling, angiogenesis and metastasis. Previously, we and others have demonstrated the role of the gelatinases MMP2 and MMP9 during the onset of NCC migration. Several evidences link the cleavage and activation of these secreted gelatinases to the activity of membrane-type MMPs (MT-MMP), such as MMP14 and MMP16, which are tethered to plasma membrane and affect various cellular behaviors. The aim of this study was to investigate whether MMP16 acts in NCCs. Here we demonstrate the expression of MMP16 mRNA and protein in cranial NCCs in avian embryos. Knockdown of MMP16 inhibited NCC migration. This inhibition was rescued by the addition of recombinant MMP16, which was also sufficient to increase proper NCC migration. Furthermore, excess MMP16 caused enhanced NCC EMT, concomitant with degradation of dNT-related proteins, laminin and N-cadherin. Altogether, these results uncover MMP16 as a new effector participating in EMT and in the migration of NCCs.

A module of inflammatory cytokines defines resistance of colorectal cancer to EGFR inhibitors.

Epidermal Growth Factor Receptor (EGFR) activates a robust signalling network to which colon cancer tumours often become addicted. Cetuximab, one of the monoclonal antibodies targeting this pathway, is employed to treat patients with colorectal cancer. However, many patients are intrinsically refractory to this treatment, and those who respond develop secondary resistance along time. Mechanisms of cancer cell resistance include either acquisition of new mutations or non genomic activation of alternative signalling routes. In this study, we employed a colon cancer model to assess potential mechanisms driving resistance to cetuximab. Resistant cells displayed increased ability to grow in suspension as colonspheres and this phenotype was associated with poorly organized structures. Factors secreted from resistant cells were causally involved in sustaining resistance, indeed administration to parental cells of conditioned medium collected from resistant cells was sufficient to reduce cetuximab efficacy. Among secreted factors, we report herein that a signature of inflammatory cytokines, including IL1A, IL1B and IL8, which are produced following EGFR pathway activation, was associated with the acquisition of an unresponsive phenotype to cetuximab in vitro. This signature correlated with lack of response to EGFR targeting also in patient-derived tumour xenografts. Collectively, these results highlight the contribution of inflammatory cytokines to reduced sensitivity to EGFR blockade and suggest that inhibition of this panel of cytokines in combination with cetuximab might yield an effective treatment strategy for CRC patients refractory to anti-EGFR targeting.

Yield of screening colonoscopy in renal transplant candidates.

BACKGROUND: Cardiovascular disease is the most common cause of death among patients with end-stage renal disease undergoing maintenance dialysis. Renal transplantation offers a survival advantage to patients with end-stage renal disease; it is also associated with a three- to fivefold increase in the risk of developing a neoplasm. OBJECTIVE: To determine the yield of screening colonoscopy among patients with chronic kidney disease who were considered for renal transplantation. METHODS: Patients were included if they were ≥50 years of age, had chronic kidney disease and were being considered for renal transplantation. They underwent a screening colonoscopy that was performed as part of their pretransplant workup. Data from December 2008 to May 2014 were collected retrospectively for all eligible patients. RESULTS: During the study period, 433 patients were considered for renal transplantation. Of these, 170 underwent colonoscopies as part of their pretransplant workup. One was excluded because of previous history of colon cancer. Of the 169 procedures performed, ≥1 polyp(s) was diagnosed in 24%. The most common pathological diagnoses were hyperplastic polyp or normal colonic tissue. Fifteen (37%) patients had tubular adenomas and one patient had a sessile serrated adenoma. Advanced adenomas, defined as villous, tubulovillous or high-grade dysplasia, were found in four patients. Adenocarcinoma was diagnosed in one patient. CONCLUSION: In a population of asymptomatic potential kidney transplant recipients ≥50 years of age, the prevalence of colorectal adenomatous polyps was 24%. Colonoscopy appeared to be useful as a screening tool in potential transplant recipients.

Navigator-3, a modulator of cell migration, may act as a suppressor of breast cancer progression.

Dissemination of primary tumor cells depends on migratory and invasive attributes. Here, we identify Navigator-3 (NAV3), a gene frequently mutated or deleted in human tumors, as a regulator of epithelial migration and invasion. Following induction by growth factors, NAV3 localizes to the plus ends of microtubules and enhances their polarized growth. Accordingly, NAV3 depletion trimmed microtubule growth, prolonged growth factor signaling, prevented apoptosis and enhanced random cell migration. Mathematical modeling suggested that NAV3-depleted cells acquire an advantage in terms of the way they explore their environment. In animal models, silencing NAV3 increased metastasis, whereas ectopic expression of the wild-type form, unlike expression of two, relatively unstable oncogenic mutants from human tumors, inhibited metastasis. Congruently, analyses of > 2,500 breast and lung cancer patients associated low NAV3 with shorter survival. We propose that NAV3 inhibits breast cancer progression by regulating microtubule dynamics, biasing directionally persistent rather than random migration, and inhibiting locomotion of initiated cells.

Diurnal suppression of EGFR signalling by glucocorticoids and implications for tumour progression and treatment.

Signal transduction by receptor tyrosine kinases (RTKs) and nuclear receptors for steroid hormones is essential for body homeostasis, but the cross-talk between these receptor families is poorly understood. We observed that glucocorticoids inhibit signalling downstream of EGFR, an RTK. The underlying mechanism entails suppression of EGFR's positive feedback loops and simultaneous triggering of negative feedback loops that normally restrain EGFR. Our studies in mice reveal that the regulation of EGFR's feedback loops by glucocorticoids translates to circadian control of EGFR signalling: EGFR signals are suppressed by high glucocorticoids during the active phase (night-time in rodents), while EGFR signals are enhanced during the resting phase. Consistent with this pattern, treatment of animals bearing EGFR-driven tumours with a specific kinase inhibitor was more effective if administered during the resting phase of the day, when glucocorticoids are low. These findings support a circadian clock-based paradigm in cancer therapy.

Sargramostim (GM-CSF) for induction of remission in Crohn's disease: a cochrane inflammatory bowel disease and functional bowel disorders systematic review of randomized trials.

BACKGROUND: We planned to systematically review the efficacy of sargramostim (granulocyte colony stimulating factor [GM-CSF]) for remission induction in patients with Crohn's disease (CD). METHODS: A literature search to April 2011 was performed to identify all randomized trials studying sargramostim in patients with CD. The Cochrane risk of bias tool was used to evaluate study quality and the GRADE criteria were utilized to assess the overall quality of the evidence. RESULTS: Three randomized studies (total 537 patients) were identified. The risk of bias was low for the three included studies. There was no statistically significant difference in the proportion of patients who achieved clinical remission (GM-CSF 25.3%; placebo 17.5%; relative risk [RR] 1.67; 95% confidence interval [CI] 0.80-3.50; P = 0.17), or 100-point clinical response (GM-CSF 38.3%; placebo 24.8%; RR 1.71 95% CI 0.98-2.97; P = 0.06). There was no statistically significant difference in the proportion of patients (GM-CSF 95.8%; placebo 89.3%) who experienced adverse events (RR 1.07; 95% CI 0.99-1.16; P = 0.08), or serious adverse events (GM-CSF 12.0% vs. placebo 4.8%; RR 2.21; 95% CI 0.84-5.81; P = 0.11). CONCLUSIONS: Sargramostim does not appear to be more effective than placebo for induction of clinical remission or improvement in active CD. However, the GRADE analysis indicates that the overall quality of the evidence for the primary and secondary outcomes was low due to sparse data and heterogeneity, indicating that further research likely would have a significant impact on the effect estimates.

Somatostatin analogues for the treatment of enterocutaneous fistulas: a systematic review and meta-analysis.

BACKGROUND: Enterocutaneous fistulas are abnormal connections between the skin and gastrointestinal tract that most commonly occur after surgery. Somatostatin analogues have been used in their treatment. The objective of the present study was to determine if somatostatin analogues shorten the time to closure of postoperative enterocutaneous fistulas compared to placebo. METHODS: We searched Medline, EMBase, the Cochrane Central Register of Controlled Trials, as well as reference lists of textbooks and relevant articles for randomized controlled trials (RCT) comparing somatostatin analogues to control in the treatment of postoperative enterocutaneous fistulas. We systematically assessed trials for eligibility and validity, and extracted data in duplicate. We pooled data across studies using a random effects model. RESULTS: Our initial search yielded 720 studies, of which eight RCT ultimately met eligibility criteria and were included in this review. Somatostatin analogues significantly decreased the time to closure of fistulas compared to placebo {weighted mean difference (WMD)--6.37 days [95% confidence interval (CI) -8.33, -4.42]}. The duration of hospital stay was also significantly decreased with somatostatin analogue treatment [WMD--4.53 days (95% CI -8.29, -0.77)]. No difference in mortality was identified with somatostatin treatment [RR 0.87 (95% CI 0.49-1.55)]. CONCLUSIONS: Somatostatin analogues appear to decrease the duration of enterocutaneous fistulas and duration of hospital stay, but no mortality benefit was identified. The quality of evidence for outcomes in this review ranged from low to moderate. Future large, blinded, RCT would be useful in improving the confidence in the treatment effects identified in this systematic review and meta-analysis.

Matrix metalloproteinase 9/gelatinase B is required for neural crest cell migration.

This study determined the role of MMP9/gelatinase B during the migration onset of Neural Crest Cells (NCC) in avian embryos. NCC are neuroepithelial progenitors that convert into mesenchyme and migrate along defined paths throughout the embryo. To engage in migration, NCC loose cell contacts, detach from the neural tube and invade the surrounding environment. Multiple signals and transcription factors that regulate these events have been identified. Nevertheless, little is known regarding effectors that act downstream to execute the actual NCC migration. Matrix metalloproteinases (MMPs) compose a large family of enzymes whose principal substrates are basement membranes, adhesion proteins and the extracellular matrix (ECM) components. A major subgroup of MMPs, the gelatinases (MMP9 and 2) are central to many adult physiological and pathological processes, such as tumor metastasis and angiogenesis, in which cell-cell and cell-matrix contacts are degraded to allow migration. As NCC undergo similar processes during development, we hypothesized that MMP9 may also promote the migration of NCC. MMP9 was found to be expressed in delaminating and migrating NCC of both cranial and trunk axial levels. Blocking MMP9 resulted in a dramatic inhibition of NCC delamination and migration, without perturbing specification or survival. This inhibition occurred at regions containing both premigratory and migrating cells, indicative for the central role of MMP9 in executing the detachment of NCC from the neural tube as well as their migration. Conversely, excess MMP9 enhanced mesenchymalization and delamination of NCC and accelerated progenitors to undergo precocious migration. Examination of the mechanistic activity of MMP9 revealed its capability to degrade the adhesion molecule N-cadherin as well as the basement-membrane protein laminin within or around NCC, respectively. Altogether, our study reveals MMP9 as a novel effector which is required for NCC delamination and migration.

Sargramostim (GM-CSF) for induction of remission in Crohn's disease.

BACKGROUND: Crohn's disease is an inflammatory condition of the gut, thought to involve an overactive immune response to gut flora. A novel theory postulates possible immunodeficiency as a cause, and aims to use sargramostim (granulocyte macrophage colony stimulating factor, GM-CSF) to boost the immune system in an effort to test this hypothesis. OBJECTIVES: The primary objectives were to determine the efficacy and safety of sargramostim for induction of remission in patients with clinically active Crohn's disease. SEARCH METHODS: A systematic search of MEDLINE, EMBASE, and CENTRAL was conducted from inception to April 2011. Reference lists of relevant review articles were also searched. Trial registries and abstract databases including Digestive Diseases Week (1980-2010) and United European Gastroenterology Week (2005-2009) were searched to identify studies published in abstract form. SELECTION CRITERIA: Randomized controlled trials of sargramostim for the treatment of patients with active Crohn's disease were considered for inclusion. DATA COLLECTION AND ANALYSIS: Data from selected articles were extracted and the Cochrane Risk of Bias tool applied independently by two authors. The primary outcome was induction of clinical remission as defined by a Crohn's Disease Activity Index (CDAI) of < 150 at the end of treatment. Secondary outcomes included clinical responses measures on the CDAI and safety outcomes. Pooled risk ratios (RR) and 95% confidence intervals (CI) were calculated for dichotomous outcomes, in most cases using a random effects model due to high heterogeneity. MAIN RESULTS: Three studies were identified, 2 published as full papers and one in abstract form (537 patients). The risk of bias was low for the 3 included studies. There was no statistically significant difference in the proportion of patients (GM-CSF 25.3% versus placebo 17.5%) who achieved clinical remission (RR 1.67; 95% CI 0.80 to 3.50; P = 0.17; 3 studies; 537 patients). There was no statistically significant difference in the proportion of patients (GM-CSF 38.3% versus placebo 24.8%) who achieved a 100-point clinical response (RR 1.71 95% CI 0.98 to 2.97; P = 0.06; 3 studies; 537 patients). There was no statistically significant difference in the proportion of patients (GM-CSF 54.3% versus placebo 44.2%) who achieved a 70 point clinical response (RR 1.23; 95% CI 0.83 to 1.82; P = 0.30; 1 study; 124 patients). There was no statistically significant difference in the proportion of patients (GM-CSF 95.8% versus placebo 89.3%) who experienced at least one adverse event (RR 1.07; 95% CI 0.99 to 1.16; P = 0.08; 2 studies; 251 patients), or serious adverse events (GM-CSF 12.0% versus placebo 4.8%; RR 2.21; 95% CI 0.84 to 5.81; P = 0.11; 2 studies; 251 patients). The incidence of bone pain, musculoskeletal chest pain, and dyspnea were higher in patients treated with sargramostim compared to placebo. Other adverse events commonly associated with sargramostim such as pulmonary capillary leak syndrome, pulmonary edema, heart failure, fever, and neurotoxicity were not reported in these studies. AUTHORS' CONCLUSIONS: Sargramostim does not appear to be more effective than placebo for induction of clinical remission or clinical improvement in patients with active Crohn's disease. However, the GRADE analysis indicates that the overall quality of the evidence for the primary (clinical remission) and secondary outcomes (clinical response) was low indicating that further research is likely to have an impact on the effect estimates.

Predictors of disease severity in ulcerative colitis patients from Southwestern Ontario.

AIM: To understand the demographic characteristics of patients in Southwestern Ontario, Canada with ulcerative colitis (UC) in order to predict disease severity. METHODS: Records from 1996 to 2001 were examined to create a database of UC patients seen in the London Health Sciences Centre South Street Hospital Inflammatory Bowel Disease Clinic. To be included, patients' charts were required to have information of their disease presentation and a minimum of 5 years of follow-up. Charts were reviewed using standardized data collection forms. Disease severity was generated during the chart review process, and non-endoscopic Mayo Score criteria were collected into a composite. RESULTS: One hundred and two consecutive patients' data were entered into the database. Demographic analyses revealed that 51% of the patients were male, the mean age at diagnosis was 39 years, 13.7% had a first degree relative with inflammatory bowel disease (IBD), 61.8% were nonsmokers and 24.5% were ex-smokers. In 22.5% of patients the disease was limited to the rectum, in 21.6% disease was limited to the sigmoid colon, in 22.5% disease was limited to the left colon, and 32.4% of patients had pancolitis. Standard multiple regression analysis which regressed a composite of physician global assessment of disease severity, average number of bowel movements, and average amount of blood in bowel movements on year of diagnosis and age at time of diagnosis was significant, R(2) = 0.306, F (7, 74) = 4.66, P < 0.01. Delay from symptoms to diagnosis of UC, gender, family history of IBD, smoking status and disease severity at the time of diagnosis did not significantly predict the composite measure. CONCLUSION: UC severity is associated with younger age at diagnosis and year of diagnosis in a longitudinal cohort of UC patients, and may identify prognostic UC indicators.