Management of de novo metastatic hormone-sensitive prostate cancer: A comprehensive report of a single-center experience.

BACKGROUND: Upfront docetaxel or novel hormonal agents (NHA) such as abiraterone and enzalutamide have become the standard of care for metastatic hormone sensitive prostate cancer (mHSPC). We evaluated real-world management of patients treated with these agents at a single center. PATIENTS AND METHODS: Patients with de novo mHSPC treated with upfront docetaxel or an NHA between January 2014 and April 2019 at Mount Sinai Health System were included. We evaluated time to next treatment (TTNT), PSA progression free survival (PFS) and overall survival (OS) after initial treatment with these drugs. Kaplan Meier method and multivariable Cox proportional hazards models were used for analysis. We additionally assessed the prognostic value of post-treatment PSA. RESULTS: We identified 94 de novo mHSPC patients; 52 and 42 treated with upfront docetaxel and NHAs, respectively. NHAs were associated with a median TTNT of 20.7 months compared to 10.1 months with docetaxel (log-rank p = 0.023). We also observed median PSA PFS of 19 months for NHAs and 13.2 months for docetaxel (p = 0.069). However, OS between the two treatment groups was unchanged. Among docetaxel treated patients, TTNT was shorter among those with high metastasis burden (9.63 vs 25.5 months, p = 0.026) which was not observed among NHA treated patients (25.1 vs 20.7 months, p = 0.79). Regardless of treatment, lower post-treatment PSA levels were associated with improved TTNT (58.95 vs. 11.57 vs. 9.4 months for PSA ≤0.2, 0.2-0.4, >0.4ng/ml, respectively; p<0.001). CONCLUSION: Real world data demonstrated a shorter duration of treatment with docetaxel than NHAs, reflecting the time-limited nature of docetaxel regimens compared to the treat-till-progression approach of NHAs. While TTNT was generally longer for NHAs than docetaxel, some docetaxel-treated patients achieved significant periods of time off treatment. In addition, the depth of PSA response following combination treatment may hold prognostic value for mHSPC outcomes.

Mice Expressing Cosegregating Single Nucleotide Polymorphisms (D298G and N397I) in TLR4 Have Enhanced Responses to House Dust Mite Allergen.

Asthma is a common and ubiquitous chronic respiratory disease that is associated with airway inflammation and hyperreactivity resulting in airway obstruction. It is now accepted that asthma is controlled by a combination of host genetics and environment in a rather complex fashion; however, the link between sensing of the environment and development and exacerbation of allergic lung inflammation is unclear. Human populations expressing cosegregating D299G and T399I polymorphisms in the TLR4 gene are associated with a decreased risk for asthma in adults along with hyporesponsiveness to inhaled LPS, the TLR4 ligand. However, these data do not account for other human genetic or environmental factors. Using a novel mouse strain that expresses homologous human TLR4 polymorphisms (TLR4-single nucleotide polymorphism [SNP]), we directly tested the effect of these TLR4 polymorphisms on in vivo responses to allergens using two models of induction. We report that intact TLR4 is required for allergic inflammation when using the OVA and LPS model of induction, as cellular and pathological benchmarks were diminished in both TLR4-SNP and TLR4-deficent mice. However, in the more clinically relevant model using house dust mite extract for induction, responses were enhanced in the TLR4-SNP mice, as evidenced by greater levels of eosinophilic inflammation, Th2 cytokine production, and house dust mite-specific IgG1 production compared with wild-type mice; however, mucus production and airway hyperreactivity were not affected. These results suggest that the TLR4 polymorphic variants (genes) interact differently with the allergic stimulation (environment).

Targeted Next-Generation Sequencing Reveals Exceptionally High Rates of Molecular Driver Mutations in Never-Smokers With Lung Adenocarcinoma.

INTRODUCTION: Historically, high rates of actionable driver mutations have been reported in never-smokers with lung adenocarcinoma (ADC). In the era of modern, comprehensive cancer mutation sequencing, this relationship necessitates a more detailed analysis. METHODS: All Mount Sinai patients between January 1, 2015, and June 1, 2020, with a diagnosis of ADC of any stage with known smoking status who received genomic testing were included. Most patients were analyzed using the Sema4 hotspot panel or the Oncomine Comprehensive Assay version 3 next-generation sequencing (NGS) panel conducted at Sema4. Patients were considered fully genotyped if they were comprehensively analyzed for alterations in EGFR, KRAS, MET, ALK, RET, ROS1, BRAF, NTRK1-3, and ERBB2, otherwise they were considered partially genotyped. RESULTS: Two hundred and thirty-six never-smokers and 671 smokers met the above criteria. Of the never-smokers, 201 (85%) had a driver mutation with 167 (71%) considered actionable (ie, those with US Food and Drug Administration-approved agents). Among smokers, 439 (65%) had an identified driver mutation with 258 (38%) actionable (P < .0001). When comprehensively sequenced, 95% (70/74) of never-smokers had a driver mutation with 78% (58/74) actionable; whereas, for smokers, 75% (135/180) had a driver with only 47% (74/180) actionable (P < .0001). Within mutations groups, EGFR G719X and KRAS G12Cs were more common to smokers. For stage IV patients harboring EGFR-mutant tumors treated with EGFR-directed therapies, never-smokers had significantly improved OS compared to smokers (hazard ratio = 2.71; P = .025). In multivariable analysis, Asian ancestry and female sex remained significant predictors of (1) OS in stage IV patients and (2) likelihood of harboring a receptor of fusion-based driver. CONCLUSION: Comprehensive NGS revealed driver alterations in 95% of never-smokers, with the majority having an associated therapy available. All efforts should be exhausted to identify or rule out the presence of an actionable driver mutation in all metastatic lung ADC.

Impact of body mass index on the efficacy of aromatase inhibitors in patients with metastatic breast cancer.

PURPOSE: Higher levels of estrogen in obese patients may lead to incomplete inhibition by aromatase inhibitors (AIs). The aim of this study was to determine the impact of body mass index (BMI) on efficacy of AIs in patients with metastatic hormone receptor (HR)-positive breast cancer (BC). METHODS: We performed a retrospective chart review of all female patients with metastatic HR-positive BC on an AI in first- or second-line settings and seen at our academic institution between 2001 and 2020. The primary endpoint was progression-free survival (PFS), defined as the time from start of AI to disease progression or death from any cause. RESULTS: We identified 219 patients who had received an AI in the first- or second-line settings for metastatic HR-positive BC and with documented information on BMI. Of the 219 patients, 56% (123) had a low BMI (defined as < 27 kg/m2) and 44% (96) had a high BMI (≥ 27 kg/m2). The median PFS was 21.9 months (95% CI 14.5 to 28.4) in the low BMI group versus 20.2 months (95% CI 14.3 to 27.5) in the high BMI group (p = 0.73). CONCLUSION: While BMI influences efficacy of AIs in the adjuvant setting, our results suggest that in the metastatic setting, BMI may not impact the efficacy of AIs. This discrepancy could be due to other differences in disease characteristics that make complete aromatase inhibition more important in the adjuvant setting when disease burden is the lowest.

USP8 and TP53 Drivers are Associated with CNV in a Corticotroph Adenoma Cohort Enriched for Aggressive Tumors.

CONTEXT: Pituitary corticotroph adenomas are rare tumors that can be associated with excess adrenocorticotropin (ACTH) and adrenal cortisol production, resulting in the clinically debilitating endocrine condition Cushing disease. A subset of corticotroph tumors behave aggressively, and genomic drivers behind the development of these tumors are largely unknown. OBJECTIVE: To investigate genomic drivers of corticotroph tumors at risk for aggressive behavior. DESIGN: Whole-exome sequencing of patient-matched corticotroph tumor and normal deoxyribonucleic acid (DNA) from a patient cohort enriched for tumors at risk for aggressive behavior. SETTING: Tertiary care center. PATIENTS: Twenty-seven corticotroph tumors from 22 patients were analyzed. Twelve tumors were macroadenomas, of which 6 were silent ACTH tumors, 2 were Crooke's cell tumors, and 1 was a corticotroph carcinoma. INTERVENTION: Whole-exome sequencing. MAIN OUTCOME MEASURE: Somatic mutation genomic biomarkers. RESULTS: We found recurrent somatic mutations in USP8 and TP53 genes, both with higher allelic fractions than other somatic mutations. These mutations were mutually exclusive, with TP53 mutations occurring only in USP8 wildtype (WT) tumors, indicating they may be independent driver genes. USP8-WT tumors were characterized by extensive somatic copy number variation compared with USP8-mutated tumors. Independent of molecular driver status, we found an association between invasiveness, macroadenomas, and aneuploidy. CONCLUSIONS: Our data suggest that corticotroph tumors may be categorized into a USP8-mutated, genome-stable subtype versus a USP8-WT, genome-disrupted subtype, the latter of which has a TP53-mutated subtype with high level of chromosome instability. These findings could help identify high risk corticotroph tumors, namely those with widespread CNV, that may need closer monitoring and more aggressive treatment.

Giardia lamblia: Laboratory Maintenance, Lifecycle Induction, and Infection of Murine Models.

Giardia lamblia is a protozoan parasite that is found ubiquitously throughout the world and is a major contributor to diarrheal disease. Giardia exhibits a biphasic lifestyle existing as either a dormant cyst or a vegetative trophozoite. Infections are typically initiated through the consumption of cyst-contaminated water or food. Giardia was first axenized in the 1970s and can be readily maintained in a laboratory setting. Additionally, Giardia is one of the few protozoans that can be induced to complete its complete lifecycle using laboratory methods. In this article, we outline protocols to maintain Giardia and induce passage through its lifecycle. We also provide protocols for infecting and quantifying parasites in an animal infection model. © 2020 Wiley Periodicals LLC. Basic Protocol 1: In vitro maintenance and growth of Giardia trophozoites Basic Protocol 2: In vitro encystation of Giardia cysts Basic Protocol 3: In vivo infections using Giardia trophozoites.

Recent insights into innate and adaptive immune responses to Giardia.

Infection with Giardia produces a wide range of clinical outcomes. Acutely infected patients may have no overt symptoms or suffer from severe cramps, diarrhea, nausea and even urticaria. Recently, post-infectious irritable bowel syndrome and chronic fatigue syndrome have been identified as long-term sequelae of giardiasis. Frequently, recurrent and chronic Giardia infection is considered a major contributor to stunting in children from low and middle income countries. Perhaps the most unusual outcome of infection with Giardia is the apparent reduced risk of developing moderate-to-severe diarrhea due to other enteric infections which has been noted in several recent studies. The goal of understanding immune responses against Giardia is therefore to identify protective mechanisms which could become targets for vaccine development, but also to identify mechanisms whereby infections lead to these other diverse outcomes. Giardia induces a robust adaptive immune response in both humans and animals. It has been known for many years that there is production of large amounts of parasite-specific IgA following infection and that CD4+ T cell responses contribute to this IgA production and control of the infection. In the past decade, there have been advances in our understanding of the non-antibody effector mechanisms used by the host to fight Giardia infections, in particular the importance of the cytokine interleukin (IL)-17 in orchestrating these responses. There have also been major advances in understanding how the innate response to Giardia infection is initiated and how it contributes to the development of adaptive immunity. Finally, there here have been significant increases in our knowledge of how the resident microbial community influences the immune response and how these responses contribute to the development of some of the symptoms of giardiasis. In this article, we will focus on data generated in the last 10 years and how it has advanced our knowledge about this important parasitic disease.

Proliferation of Resident Macrophages Is Dispensable for Protection during Giardia duodenalis Infections.

Infection with the intestinal parasite Giardia duodenalis is one of the most common causes of diarrheal disease in the world. Previous work has demonstrated that the cells and mechanisms of the adaptive immune system are critical for clearance of this parasite. However, the innate system has not been as well studied in the context of Giardia infection. We have previously demonstrated that Giardia infection leads to the accumulation of a population of CD11b+, F4/80+, ARG1+, and NOS2+ macrophages in the small intestinal lamina propria. In this report, we sought to identify the accumulation mechanism of duodenal macrophages during Giardia infection and to determine if these cells were essential to the induction of protective Giardia immunity. We show that F4/80+, CD11b+, CD11cint, CX3CR1+, MHC class II+, Ly6C-, ARG1+, and NOS2+ macrophages accumulate in the small intestine during infections in mice. Consistent with this resident macrophage phenotype, macrophage accumulation does not require CCR2, and the macrophages incorporate EdU, indicating in situ proliferation rather than the recruitment of monocytes. Depletion of macrophages using anti-CSF1R did not impact parasite clearance nor development of regulatory T cell or Th17 cellular responses, suggesting that these macrophages are dispensable for protective Giardia immunity.

Distinction of Fly Artifacts from Human Blood using Immunodetection.

Insect stains produced by necrophagous flies are indistinguishable morphologically from human bloodstains. At present, no diagnostic tests exist to overcome this deficiency. As the first step toward developing a chemical test to recognize fly artifacts, polyclonal antisera were generated in rats against three distinct antigenic sequences of fly cathepsin D-like proteinase, an enzyme that is structurally distinct in cyclorrhaphous Diptera from other animals. The resulting rat antisera bound to artifacts produced by Protophormia terraenovae and synthetic peptides used to generate the polyclonal antisera, but not with any type of mammalian blood tested in immunoassays. Among the three antisera, anti-md3 serum displayed the highest reactivity for fly stains, demonstrated cross-reactivity for all synthetic peptides representing antigenic sequences of the mature fly enzyme, and bound artifacts originating from the fly digestive tract. Further work is needed to determine whether the antisera are suitable for non-laboratory conditions.

The Intersection of Immune Responses, Microbiota, and Pathogenesis in Giardiasis.

Giardia lamblia is one of the most common infectious protozoans in the world. Giardia rarely causes severe life-threatening diarrhea, and may even have a slight protective effect in this regard, but it is a major contributor to malnutrition and growth faltering in children in the developing world. Giardia infection also appears to be a significant risk factor for postinfectious irritable bowel and chronic fatigue syndromes. In this review we highlight recent work focused on the impact of giardiasis and the mechanisms that contribute to the various outcomes of this infection, including changes in the composition of the microbiota, activation of immune responses, and immunopathology.

Identification of a novel RASD1 somatic mutation in a USP8-mutated corticotroph adenoma.

Cushing's disease (CD) is caused by pituitary corticotroph adenomas that secrete excess adrenocorticotropic hormone (ACTH). In these tumors, somatic mutations in the gene USP8 have been identified as recurrent and pathogenic and are the sole known molecular driver for CD. Although other somatic mutations were reported in these studies, their contribution to the pathogenesis of CD remains unexplored. No molecular drivers have been established for a large proportion of CD cases and tumor heterogeneity has not yet been investigated using genomics methods. Also, even in USP8-mutant tumors, a possibility may exist of additional contributing mutations, following a paradigm from other neoplasm types where multiple somatic alterations contribute to neoplastic transformation. The current study utilizes whole-exome discovery sequencing on the Illumina platform, followed by targeted amplicon-validation sequencing on the Pacific Biosciences platform, to interrogate the somatic mutation landscape in a corticotroph adenoma resected from a CD patient. In this USP8-mutated tumor, we identified an interesting somatic mutation in the gene RASD1, which is a component of the corticotropin-releasing hormone receptor signaling system. This finding may provide insight into a novel mechanism involving loss of feedback control to the corticotropin-releasing hormone receptor and subsequent deregulation of ACTH production in corticotroph tumors.

Genomic profiling reveals mutational landscape in parathyroid carcinomas.

Parathyroid carcinoma (PC) is an extremely rare malignancy lacking effective therapeutic intervention. We generated and analyzed whole-exome sequencing data from 17 patients to identify somatic and germline genetic alterations. A panel of selected genes was sequenced in a 7-tumor expansion cohort. We show that 47% (8 of 17) of the tumors harbor somatic mutations in the CDC73 tumor suppressor, with germline inactivating variants in 4 of the 8 patients. The PI3K/AKT/mTOR pathway was altered in 21% of the 24 cases, revealing a major oncogenic pathway in PC. We observed CCND1 amplification in 29% of the 17 patients, and a previously unreported recurrent mutation in putative kinase ADCK1. We identified the first sporadic PCs with somatic mutations in the Wnt canonical pathway, complementing previously described epigenetic mechanisms mediating Wnt activation. This is the largest genomic sequencing study of PC, and represents major progress toward a full molecular characterization of this rare malignancy to inform improved and individualized treatments.

Development and clinical application of an integrative genomic approach to personalized cancer therapy.

BACKGROUND: Personalized therapy provides the best outcome of cancer care and its implementation in the clinic has been greatly facilitated by recent convergence of enormous progress in basic cancer research, rapid advancement of new tumor profiling technologies, and an expanding compendium of targeted cancer therapeutics. METHODS: We developed a personalized cancer therapy (PCT) program in a clinical setting, using an integrative genomics approach to fully characterize the complexity of each tumor. We carried out whole exome sequencing (WES) and single-nucleotide polymorphism (SNP) microarray genotyping on DNA from tumor and patient-matched normal specimens, as well as RNA sequencing (RNA-Seq) on available frozen specimens, to identify somatic (tumor-specific) mutations, copy number alterations (CNAs), gene expression changes, gene fusions, and also germline variants. To provide high sensitivity in known cancer mutation hotspots, Ion AmpliSeq Cancer Hotspot Panel v2 (CHPv2) was also employed. We integrated the resulting data with cancer knowledge bases and developed a specific workflow for each cancer type to improve interpretation of genomic data. RESULTS: We returned genomics findings to 46 patients and their physicians describing somatic alterations and predicting drug response, toxicity, and prognosis. Mean 17.3 cancer-relevant somatic mutations per patient were identified, 13.3-fold, 6.9-fold, and 4.7-fold more than could have been detected using CHPv2, Oncomine Cancer Panel (OCP), and FoundationOne, respectively. Our approach delineated the underlying genetic drivers at the pathway level and provided meaningful predictions of therapeutic efficacy and toxicity. Actionable alterations were found in 91 % of patients (mean 4.9 per patient, including somatic mutations, copy number alterations, gene expression alterations, and germline variants), a 7.5-fold, 2.0-fold, and 1.9-fold increase over what could have been uncovered by CHPv2, OCP, and FoundationOne, respectively. The findings altered the course of treatment in four cases. CONCLUSIONS: These results show that a comprehensive, integrative genomic approach as outlined above significantly enhanced genomics-based PCT strategies.

Altered Transcriptional Control Networks with Trans-Differentiation of Isogenic Mutant-KRas NSCLC Models.

BACKGROUND: The capacity of cancer cells to undergo epithelial mesenchymal trans-differentiation has been implicated as a factor driving metastasis, through the acquisition of enhanced migratory/invasive cell programs and the engagement of anti-apoptotic mechanisms promoting drug and radiation resistance. Our aim was to define molecular signaling changes associated with mesenchymal trans-differentiation in two KRas mutant NSCLC models. We focused on central transcription and epigenetic regulators predicted to be important for mesenchymal cell survival. EXPERIMENTAL DESIGN: We have modeled trans-differentiation and cancer stemness in inducible isogenic mutant-KRas H358 and A549 non-small cell lung cell backgrounds. As expected, our models show mesenchymal-like tumor cells acquire novel mechanisms of cellular signaling not apparent in their epithelial counterparts. We employed large-scale quantitative phosphoproteomic, proteomic, protein-protein interaction, RNA-Seq, and network function prediction approaches to dissect the molecular events associated with the establishment and maintenance of the mesenchymal state. RESULTS: Gene-set enrichment and pathway prediction indicated BMI1, KDM5B, RUNX2, MYC/MAX, NFκB, LEF1, and HIF1 target networks were significantly enriched in the trans-differentiation of H358 and A549 NSCLC models. Physical overlaps between multiple networks implicate NR4A1 as an overlapping control between TCF and NFκB pathways. Enrichment correlations also indicated marked decrease in cell cycling, which occurred early in the EMT process. RNA abundance time course studies also indicated early expression of epigenetic and chromatin regulators within 8-24 h, including CITED4, RUNX3, CMBX1, and SIRT4. CONCLUSION: Multiple transcription and epigenetic pathways where altered between epithelial and mesenchymal tumor cell states, notably the polycomb repressive complex-1, HP1γ, and BAF/Swi-Snf. Network analysis suggests redundancy in the activation and inhibition of pathway regulators, notably factors controlling epithelial cell state. Through large-scale transcriptional and epigenetic cell reprograming, mesenchymal trans-differentiation can promote diversification of signaling networks potentially important in resistance to cancer therapies.

Spatial characterization of proteolytic enzyme activity in the foregut region of the adult necrophagous fly, Protophormia terraenovae.

The spatial distribution of proteolytic enzymes in the adult foregut of Protophormia terraenovae was studied in the context of protein digestion and regurgitation. Based on substrate specificity, pH optima, and use of specific protease inhibitors, all adults tested displayed enzyme activity in the foregut consistent with pepsin, trypsin and chymotrypsin. Chymotrypsin-like and trypsin-like enzyme activity were detected in all gut fluids and tissues tested, with chymotrypsin displaying the highest activity in saliva and salivary gland tissue, whereas maximal trypsin activity was evident in the crop. Pepsin-like activity was only evident in crop fluids and tissues. The activity of all three enzymes was low or undetectable (pepsin) in the fluids and tissue homogenates derived from the esophagus and cardia of any of the adults assayed. Fed adult females displayed higher enzyme activities than fed males, and the activity of all three enzymes were much more prevalent in fed adults than starved. The pH optimum of the trypsin-like enzyme was between pH 7.0 and 8.0; chymotrypsin was near pH 8.0; and maximal pepsin-like activity occurred between pH 1.0 and 2.0. Regurgitate from fed adult females displayed enzyme activity consistent with the proteolytic enzymes detected in crop gut fluids. Enzymes in regurgitate were not derived from food sources based on assays of bovine liver samples. These latter observations suggest that adult flies release fluids from foregut when encountering dry foods, potentially as a means to initiate extra-oral digestion.

Survival of HER2-Positive Breast Cancer Cells: Receptor Signaling to Apoptotic Control Centers.

HER2 is overexpressed in a subset of breast cancers and controls an oncogenic signaling network that inhibits tumor cell death through the specific biochemical regulation of apoptotic pathways. In particular, the mitochondrial pathway for apoptosis is important for death induced by inhibitors of HER2. This review focuses on the connections between this oncogenic signaling network and individual components of the mitochondrial pathway. A comprehensive view of this signaling network is crucial for developing novel drugs in this area and to gain an understanding of how these regulatory interactions are altered in drug-refractory cancers.

Research resource: Gonadotropin-releasing hormone receptor-mediated signaling network in LbetaT2 cells: a pathway-based web-accessible knowledgebase.

The GnRH receptor (GnRHR), expressed at the cell surface of the anterior pituitary gonadotrope, is critical for normal secretion of gonadotropins LH and FSH, pubertal development, and reproduction. The signaling network downstream of the GnRHR and the molecular bases of the regulation of gonadotropin expression have been the subject of intense research. The murine LbetaT2 cell line represents a mature gonadotrope and therefore is an important model for the study of GnRHR-signaling pathways and modulation of the gonadotrope cell by physiological regulators. In order to facilitate access to the information contained in this complex and evolving literature, we have developed a pathway-based knowledgebase that is web hosted. At present, using 106 relevant primary publications, we curated a comprehensive knowledgebase of the GnRHR signaling in the LbetaT2 cell in the form of a process diagram. Positive and negative controls of gonadotropin gene expression, which included GnRH itself, hypothalamic factors, gonadal steroids and peptides, as well as other hormones, were illustrated. The knowledgebase contains 187 entities and 206 reactions. It was assembled using CellDesigner software, which provides an annotated graphic representation of interactions, stored in Systems Biology Mark-up Language. We then utilized Biological Pathway Publisher, a software suite previously developed in our laboratory, to host the knowledgebase in a web-accessible format as a public resource. In addition, the network entities were linked to a public wiki, providing a forum for discussion, updating, and error correction. The GnRHR-signaling network is openly accessible at http://tsb.mssm.edu/pathwayPublisher/GnRHR_Pathway/GnRHR_Pathway_ index.html.

Plato's cave algorithm: inferring functional signaling networks from early gene expression shadows.

Improving the ability to reverse engineer biochemical networks is a major goal of systems biology. Lesions in signaling networks lead to alterations in gene expression, which in principle should allow network reconstruction. However, the information about the activity levels of signaling proteins conveyed in overall gene expression is limited by the complexity of gene expression dynamics and of regulatory network topology. Two observations provide the basis for overcoming this limitation: a. genes induced without de-novo protein synthesis (early genes) show a linear accumulation of product in the first hour after the change in the cell's state; b. The signaling components in the network largely function in the linear range of their stimulus-response curves. Therefore, unlike most genes or most time points, expression profiles of early genes at an early time point provide direct biochemical assays that represent the activity levels of upstream signaling components. Such expression data provide the basis for an efficient algorithm (Plato's Cave algorithm; PLACA) to reverse engineer functional signaling networks. Unlike conventional reverse engineering algorithms that use steady state values, PLACA uses stimulated early gene expression measurements associated with systematic perturbations of signaling components, without measuring the signaling components themselves. Besides the reverse engineered network, PLACA also identifies the genes detecting the functional interaction, thereby facilitating validation of the predicted functional network. Using simulated datasets, the algorithm is shown to be robust to experimental noise. Using experimental data obtained from gonadotropes, PLACA reverse engineered the interaction network of six perturbed signaling components. The network recapitulated many known interactions and identified novel functional interactions that were validated by further experiment. PLACA uses the results of experiments that are feasible for any signaling network to predict the functional topology of the network and to identify novel relationships.

Structure of the GnRH receptor-stimulated signaling network: insights from genomics.

The GnRH receptor influences gene expression in the gonadotrope through activating signaling cascades that modulate transcription factor expression and activity. A longstanding question in neuroendocrinology is how instructions received at the membrane in the form of the pattern of receptor stimulation are processed into specific biosynthetic changes at each gonadotropin promoter. Signal transduction from the membrane to preformed transcription factors relies on recognition of altered conformations. Signal transduction through the layers of the gene network also requires the biosynthesis of new transcription factors. The signal processing of this system depends on its molecular connectivity map and its feedback and feed-forward loops. Review of signal transduction, gene control, and genomic studies provide evidence of key loops that cross between cellular and nuclear compartments. Genomic studies suggest that the signal transduction and gene network form a continuum. We propose that information transfer in the gonadotrope depends on robust signaling modules that serve to integrate events at different time scales across cytoplasmic and nuclear compartments.

Ankyrin binding mediates L1CAM interactions with static components of the cytoskeleton and inhibits retrograde movement of L1CAM on the cell surface.

The function of adhesion receptors in both cell adhesion and migration depends critically on interactions with the cytoskeleton. During cell adhesion, cytoskeletal interactions stabilize receptors to strengthen adhesive contacts. In contrast, during cell migration, adhesion proteins are believed to interact with dynamic components of the cytoskeleton, permitting the transmission of traction forces through the receptor to the extracellular environment. The L1 cell adhesion molecule (L1CAM), a member of the Ig superfamily, plays a crucial role in both the migration of neuronal growth cones and the static adhesion between neighboring axons. To understand the basis of L1CAM function in adhesion and migration, we quantified directly the diffusion characteristics of L1CAM on the upper surface of ND-7 neuroblastoma hybrid cells as an indication of receptor-cytoskeleton interactions. We find that cell surface L1CAM engages in diffusion, retrograde movement, and stationary behavior, consistent with interactions between L1CAM and two populations of cytoskeleton proteins. We provide evidence that the cytoskeletal adaptor protein ankyrin mediates stationary behavior while inhibiting the actin-dependent retrograde movement of L1CAM. Moreover, inhibitors of L1CAM-ankyrin interactions promote L1CAM-mediated axon growth. Together, these results suggest that ankyrin binding plays a crucial role in the anti-coordinate regulation of L1CAM-mediated adhesion and migration.