The cell adhesion molecule L1 is developmentally regulated in the renal epithelium and is involved in kidney branching morphogenesis

Expression of L1 Cell Adhesion Molecule, a Nephronal Principal Cell Marker, in Nephrogenic Adenoma

Nephrogenic adenoma (NA) is a benign, reactive lesion seen predominantly in the urinary bladder and often associated with antecedent inflammation, instrumentation, or an operative history. Its histopathologic diversity can create diagnostic dilemmas and pathologists use morphologic evaluation along with available immunohistochemical (IHC) markers to navigate these challenges. IHC assays currently do not designate or specify NA's potential putative cell of origin. Leveraging single-cell RNA-sequencing technology, we nominated a principal (P) cell-collecting duct marker, L1 cell adhesion molecule (L1CAM), as a potential biomarker for NA. IHC characterization revealed L1CAM to be positive in all 35 (100%) patient samples of NA; negative expression was seen in the benign urothelium, benign prostatic glands, urothelial carcinoma (UCA) in situ, prostatic adenocarcinoma, majority of high-grade UCA, and metastatic UCA. In the study, we also used single-cell RNA sequencing to nominate a novel compendium of biomarkers specific for the proximal tubule, loop of Henle, and distal tubule (DT) (including P and intercalated cells), which can be used to perform nephronal mapping using RNA in situ hybridization and IHC technology. Employing this technique on NA we found enrichment of both the P-cell marker L1CAM and, the proximal tubule type-A and -B cell markers, PDZKI1P1 and PIGR, respectively. The cell-type markers for the intercalated cell of DTs (LINC01187 and FOXI1), and the loop of Henle (UMOD and IRX5), were found to be uniformly absent in NA. Overall, our findings show that based on cell type-specific implications of L1CAM expression, the shared expression pattern of L1CAM between DT P cells and NA. L1CAM expression will be of potential value in assisting surgical pathologists toward a diagnosis of NA in challenging patient samples.

L1 Cell Adhesion Molecule (L1CAM) Expression and Molecular Alterations Distinguish Low-Grade Oncocytic Tumor From Eosinophilic Chromophobe Renal Cell Carcinoma

Renal low-grade oncocytic tumor (LOT) is a recently recognized renal cell neoplasm designated within the "other oncocytic tumors" category in the 2022 World Health Organization classification system. Although the clinicopathologic, immunohistochemical, and molecular features reported for LOT have been largely consistent, the data are relatively limited. The morphologic overlap between LOT and other low-grade oncocytic neoplasms, particularly eosinophilic chromophobe renal cell carcinoma (E-chRCC), remains a controversial area in renal tumor classification. To address this uncertainty, we characterized and compared large cohorts of LOT (n = 67) and E-chRCC (n = 69) and revealed notable differences between the 2 entities. Clinically, LOT predominantly affected women, whereas E-chRCC showed a male predilection. Histologically, although almost all LOTs were dominated by a small-nested pattern, E-chRCC mainly showed solid and tubular architectures. Molecular analysis revealed that 87% of LOT cases harbored mutations in the tuberous sclerosis complex (TSC)-mTOR complex 1 (mTORC1) pathway, most frequently in MTOR and RHEB genes; a subset of LOT cases had chromosomal 7 and 19q gains. In contrast, E-chRCC lacked mTORC1 mutations, and 60% of cases displayed chromosomal losses characteristic of chRCC. We also explored the cell of origin for LOT and identified L1 cell adhesion molecule (L1CAM), a collecting duct and connecting tubule principal cell marker, as a highly sensitive and specific ancillary test for differentiating LOT from E-chRCC. This distinctive L1CAM immunohistochemical labeling suggests the principal cells as the cell of origin for LOT, unlike the intercalated cell origin of E-chRCC and oncocytoma. The ultrastructural analysis of LOT showed normal-appearing mitochondria and intracytoplasmic lumina with microvilli, different from what has been described for chRCC. Our study further supports LOT as a unique entity with a benign clinical course. Based on the likely cell of origin and its clinicopathologic characteristics, we propose that changing the nomenclature of LOT to "Oncocytic Principal Cell Adenoma of the Kidney" may be a better way to define and describe this entity.

Hybrid Oncocytic Tumors (HOTs) in Birt-Hogg-Dubé Syndrome Patients-A Tale of Two Cities: Sequencing Analysis Reveals Dual Lineage Markers Capturing the 2 Cellular Populations of HOT

Birt-Hogg-Dubé (BHD) syndrome is associated with an increased risk of multifocal renal tumors, including hybrid oncocytic tumor (HOT) and chromophobe renal cell carcinoma (chRCC). HOT exhibits heterogenous histologic features overlapping with chRCC and benign renal oncocytoma, posing challenges in diagnosis of HOT and renal tumor entities resembling HOT. In this study, we performed integrative analysis of bulk and single-cell RNA sequencing data from renal tumors and normal kidney tissues, and nominated candidate biomarkers of HOT, L1CAM, and LINC01187 , which are also lineage-specific markers labeling the principal cell and intercalated cell lineages of the distal nephron, respectively. Our findings indicate the principal cell lineage marker L1CAM and intercalated cell lineage marker LINC01187 to be expressed mutually exclusively in a unique checkered pattern in BHD-associated HOTs, and these 2 lineage markers collectively capture the 2 distinct tumor epithelial populations seen to co-exist morphologically in HOTs. We further confirmed that the unique checkered expression pattern of L1CAM and LINC01187 distinguished HOT from chRCC, renal oncocytoma, and other major and rare renal cell carcinoma subtypes. We also characterized the histopathologic features and immunophenotypic features of oncocytosis in the background kidney of patients with BHD, as well as the intertumor and intratumor heterogeneity seen within HOT. We suggest that L1CAM and LINC01187 can serve as stand-alone diagnostic markers or as a panel for the diagnosis of HOT. These lineage markers will inform future studies on the evolution and interaction between the 2 transcriptionally distinct tumor epithelial populations in such tumors.

CD171 Multi-epitope peptide design based on immuno-informatics approach as a cancer vaccine candidate for glioblastoma

Glioblastoma (GB) is a common primary malignancy of the central nervous system, and one of the highly lethal brain tumors. GB cells can promote therapeutic resistance and tumor angiogenesis. The CD171 is an adhesion molecule in neuronal cells that is expressed in glioma cells as a regulator of brain development during the embryonic period. CD171 is one of the immunoglobulin-like CAMs (cell adhesion molecules) families that can be associated with prognosis in a variety of human tumors. The multi-epitope peptide vaccines are based on synthetic peptides with a combination of both B-cell epitopes and T-cell epitopes, which can induce specific humoral or cellular immune responses. Moreover, Cholera toxin subunit B (CTB), a novel TLR agonist was utilized in the final construct to polarize CD4+ T cells toward T-helper 1 to induce strong cytotoxic T lymphocytes (CTL) responses. In the present study, several immune-informatics tools were used for analyzing the CD171 sequence and studying the important characteristics of a designed vaccine. The results included molecular docking, molecular dynamics simulation, immune response simulation, prediction and validation of the secondary and tertiary structure, physicochemical properties, solubility, conservancy, toxicity as well as antigenicity and allergenicity of the promising candidate for a vaccine against CD171. The immuno-informatic analyze suggested 12 predicted multi-epitope peptides, whose construction consists of 582 residues long. Therewith, cloning adaptation of the designed vaccine was performed, and eventually sequence was inserted into pET30a (+) vector for the application of the anti-glioblastoma vaccine development.Communicated by Ramaswamy H. Sarma.

Parkinson's Disease Derived Exosomes Aggravate Neuropathology in SNCA*A53T Mice

OBJECTIVE

Accumulation of α-synuclein (α-syn) in neurons is a prominent feature of Parkinson's disease (PD). Recently, researchers have considered that extracellular vesicles (EVs) may play an important role in protein exportation and propagation, and α-syn-containing EVs derived from the central nervous system (CNS) have been detected in peripheral blood. However, mechanistic insights into CNS-derived EVs have not been well-described.

METHODS

Likely neurogenic EVs were purified from the plasma of PD patients and healthy controls using a well-established immunoprecipitation assay with anti-L1CAM-coated beads. A Prnp-SNCAA53T transgenic PD mouse model was used to evaluate the neuronal pathology induced by PD-derived L1CAM-purified EVs. EV-associated microRNA (miRNA) profiling was used to screen for altered miRNAs in PD-derived L1CAM-purified EVs.

RESULTS

PD patient-derived L1CAM-purified (likely neurogenic) EVs facilitated α-syn pathology and neuron loss in Prnp-SNCAA53T transgenic PD mice. The miRNA, novel_miR_44438, was significantly increased in the PD group, which promoted α-syn accumulation and neuronal degeneration in a dose-dependent manner. Novel _miR_44438 directly targets NDST1 mRNA and inhibits the function of heparan sulfate, thus preventing exosome biogenesis and α-syn release from exosomes.

INTERPRETATION

Novel_miR_44438 in PD-derived L1CAM-purified EVs inhibits the α-syn efflux from neurons thereby promoting the pathological accumulation and aggregation of α-syn. ANN NEUROL 2022;92:230-245.

TINY IN SIZE, BIG IN IMPACT: EXTRACELLULAR VESICLES AS MODULATORS OF MOOD, ANXIETY AND NEURODEVELOPMENTAL DISORDERS

Extracellular Vesicles (EVs) are tiny vesicles used by cells as means of cellular communication, through which the function and state of a given cell can be changed. A body of evidence has suggested that EVs could be culprits in the development and progression of various types of diseases, including neurodegenerative diseases such as Multiple Sclerosis (MS) and Alzheimer's Disease (AD). Unsurprisingly, EVs have also been implicate in mood, anxiety and neurodevelopmental disorders, such as Major Depressive Disorder (MDD), anxiety disorder and Autism-Spectrum Disorder (ASD), respectively. Here, we review the state-of-art regarding the roles of EVs in the aforementioned diseases and focus on the mechanisms by which they can cause and worsen disease. Harnessing the knowledge of EVs is not only important to deliver different cargos to cells in a specific manner to treat these diseases, but also to establish reliable disease biomarkers, which will aid in the early disease diagnosis and treatment, increasing the chance of successful treatment.

Levels of Receptor for Advanced Glycation End Products and Glyoxalase-1 in the Total Circulating Extracellular Vesicles from Mild Cognitive Impairment and Different Stages of Alzheimer's Disease Patients

BACKGROUND

Growing evidence supports that receptor for advanced glycation end products (RAGE) and glyoxalase-1 (GLO-1) are implicated in the pathophysiology of Alzheimer's disease (AD). Extracellular vesicles (EVs) are nanovesicles secreted by almost all cell types, contribute to cellular communication, and are implicated in AD pathology. Recently, EVs are considered as promising tools to identify reliable biomarkers in AD.

OBJECTIVE

The aim of our study was to determine the levels of RAGE and GLO-1 in circulating EVs from mild cognitive impairment (MCI) and AD patients and to analyze their correlation with the clinical Mini-Mental State Examination and Montreal Cognitive Assessment scores. We have studied the possibility that neuronal cells could release and transfer GLO-1 through EVs.

METHODS

RAGE and GLO-1 levels were measured in circulating EVs, respectively, by Luminex assay and western blot. Released-EVs from SK-N-SH neuronal cells were isolated and GLO-1 levels were determined by western blot.

RESULTS

Our data showed higher levels of RAGE in EVs from late AD patients while GLO-1 levels in EVs from early AD were lower as compared to control and MCI patients. Interestingly, levels of RAGE and GLO-1 in EVs were correlated with the cognitive scores regardless of age. For the first time, we demonstrated that GLO-1 was released from neuronal cells through EVs.

CONCLUSION

Although more samples will be needed, our preliminary results support the use of peripheral EVs cargo as new tools for the discovery of peripheral AD biomarkers.

Neuronal immunoglobulin superfamily cell adhesion molecules in epithelial morphogenesis: insights from Drosophila

In this review, we address the function of immunoglobulin superfamily cell adhesion molecules (IgCAMs) in epithelia. Work in the Drosophila model system in particular has revealed novel roles for calcium-independent adhesion molecules in the morphogenesis of epithelial tissues. We review the molecular composition of lateral junctions with a focus on their IgCAM components and reconsider the functional roles of epithelial lateral junctions. The epithelial IgCAMs discussed in this review have well-defined roles in the nervous system, particularly in the process of axon guidance, suggesting functional overlap and conservation in mechanism between that process and epithelial remodelling. We expand on the hypothesis that epithelial occluding junctions and synaptic junctions are compositionally equivalent and present a novel hypothesis that the mechanism of epithelial cell (re)integration and synaptic junction formation are shared. We highlight the importance of considering non-cadherin-based adhesion in our understanding of the mechanics of epithelial tissues and raise questions to direct future work. This article is part of the discussion meeting issue 'Contemporary morphogenesis'.

Novel Therapeutic Strategies for Ovarian Cancer Stem Cells

Ovarian cancer (OC) is one of the most lethal gynecologic malignancies. Due to the lack of specific symptoms and screening methods, this disease is usually diagnosed only at an advanced and metastatic stage. The gold-standard treatment for OC patients consists of debulking surgery followed by taxane combined with platinum-based chemotherapy. Most patients show complete clinical remission after first-line therapy, but the majority of them ultimately relapse, developing radio- and chemoresistant tumors. It is now proposed that the cause of recurrence and reduced therapy efficacy is the presence of small populations of cancer stem cells (CSCs). These cells are usually resistant against conventional cancer therapies and for this reason, effective targeted therapies for the complete eradication of CSCs are urgently needed. In this review article, we highlight the mechanisms of CSC therapy resistance, epithelial-to-mesenchymal transition, stemness, and novel therapeutic strategies for ovarian CSCs.

Dendrites with specialized glial attachments develop by retrograde extension using SAX-7 and GRDN-1

Dendrites develop elaborate morphologies in concert with surrounding glia, but the molecules that coordinate dendrite and glial morphogenesis are mostly unknown. C. elegans offers a powerful model for identifying such factors. Previous work in this system examined dendrites and glia that develop within epithelia, similar to mammalian sense organs. Here, we focus on the neurons BAG and URX, which are not part of an epithelium but instead form membranous attachments to a single glial cell at the nose, reminiscent of dendrite-glia contacts in the mammalian brain. We show that these dendrites develop by retrograde extension, in which the nascent dendrite endings anchor to the presumptive nose and then extend by stretching during embryo elongation. Using forward genetic screens, we find that dendrite development requires the adhesion protein SAX-7/L1CAM and the cytoplasmic protein GRDN-1/CCDC88C to anchor dendrite endings at the nose. SAX-7 acts in neurons and glia, while GRDN-1 acts in glia to non-autonomously promote dendrite extension. Thus, this work shows how glial factors can help to shape dendrites, and identifies a novel molecular mechanism for dendrite growth by retrograde extension.

Dissecting the Global Dynamic Molecular Profiles of Human Fetal Kidney Development by Single-Cell RNA Sequencing

Healthy renal function depends on normal nephrogenesis during embryonic development. However, a comprehensive gene expression profile of human fetal kidney development remains largely unexplored. Here, using a single-cell RNA-sequencing technique, we analyzed >3,000 human fetal renal cells spanning 4 months of development in utero. Unsupervised analysis identified two progenitor subtypes during cap mesenchyme development, suggesting a mechanism for sustaining their progenitor states. Furthermore, we identified critical transcriptional regulators and signaling pathways involved in the segmentation of nephron tubules. We explored the development of the highly heterogeneous collecting duct epithelia and dissected the metabolic gene repertoire and the extracellular matrix composition of the glomerular mesangium. The results provide insights on the molecular basis and regulatory events in human renal development. Moreover, the cell-type-specific expression features of causal genes in congenital renal diseases may be helpful in the treatment of these diseases.

Profile of pathogenic proteins in total circulating extracellular vesicles in mild cognitive impairment and during the progression of Alzheimer's disease

Accumulating evidence suggests that the propagation of hyperphosphorylation of tau protein and the amyloid-β peptide can be mediated by extracellular vesicles (EVs) and be associated with the onset and the progression of Alzheimer's disease (AD). As EVs may transfer between the brain and the blood, we have thus hypothesized that the total plasma EVs (pEVs) may contain potential markers to predict the mild cognitive impairment (MCI) and AD progression. We have thus quantified AD-related proteins in isolated pEVs from controls, MCI and AD subjects. In pEVs, we observed early changes of total tau (tTau), amyloid precursor protein levels, and phospho-tau (pTau)-T181/tTau ratio from MCI subjects and late increases of Aβ42 and pTau-T181 levels from patients with moderate AD. Interestingly, abnormal amyloid precursor protein levels and pTau-T181/tTau ratio in pEVs demonstrated a high accuracy to define MCI and AD staging. Although larger samples sizes will be needed to generate well-powered investigations, these preliminary results highlighted the potential of AD-related proteins enriched in pEVs as a sensitive tool for differentiating patients with MCI to patients with AD and monitoring AD progression.

Insulin-signaling abnormalities in drug-naïve first-episode schizophrenia: Transduction protein analyses in extracellular vesicles of putative neuronal origin

BACKGROUND

Metabolic syndrome and impaired insulin sensitivity may occur as side effects of atypical antipsychotic drugs. However, studies of peripheral insulin resistance using the homeostatic model assessment of insulin resistance (HOMA-IR) or oral glucose tolerance tests (OGTT) suggest that abnormal glucose metabolism is already present in drug-naive first-episode schizophrenia (DNFES). We hypothesized impairments of neuronal insulin signaling in DNFES.

METHODS

To gain insight into neuronal insulin-signaling in vivo, we analyzed peripheral blood extracellular vesicles enriched for neuronal origin (nEVs). Phosphorylated insulin signal transduction serine-threonine kinases pS312-IRS-1, pY-IRS-1, pS473-AKT, pS9-GSK3β, pS2448-mTOR, pT389-p70S6K and respective total protein levels were determined in plasma nEVs from 48 DNFES patients and healthy matched controls after overnight fasting.

RESULTS

Upstream pS312-IRS-1 was reduced at trend level (p = 0.071; this condition may amplify IRS-1 signaling). Exploratory omnibus analysis of downstream serine-threonine kinases (AKT, GSK3β, mTOR, p70S6K) revealed lower phosphorylated/total protein ratios in DNFES vs. controls (p = 0.013), confirming decreased pathway activation. Post-hoc-tests indicated in particular a reduced phosphorylation ratio of mTOR (p = 0.027). Phosphorylation ratios of p70S6K (p = 0.029), GSK3β (p = 0.039), and at trend level AKT (p = 0.061), showed diagnosis-dependent statistical interactions with insulin blood levels. The phosphorylation ratio of AKT correlated inversely with PANSS-G and PANSS-total scores, and other ratios showed similar trends.

CONCLUSION

These findings support the hypothesis of neuronal insulin resistance in DNFES, small sample sizes notwithstanding. The counterintuitive trend towards reduced pS312-IRS-1 in DNFES may result from adaptive feedback mechanisms. The observed changes in insulin signaling could be clinically meaningful as suggested by their association with higher PANSS scores.

Development of a Theranostic Convergence Bioradiopharmaceutical for Immuno-PET Based Radioimmunotherapy of L1CAM in Cholangiocarcinoma Model

PURPOSE

Cholangiocarcinoma is a malignancy of bile duct with a poor prognosis. Conventional chemotherapy and radiotherapy are generally ineffective, and surgical resection is the only curative treatment for cholangiocarcinoma. L1-cell adhesion molecule (L1CAM) has been known as a novel prognostic marker and therapeutic target for cholangiocarcinoma. This study aimed to evaluate the feasibility of immuno-PET imaging-based radioimmunotherapy using radiolabeled anti-L1CAM antibody in cholangiocarcinoma xenograft model.

EXPERIMENTAL DESIGN

We prepared a theranostic convergence bioradiopharmaceutical using chimeric anti-L1CAM antibody (cA10-A3) conjugated with 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) chelator and labeled with ⁶⁴Cu or ¹⁷⁷Lu and evaluated the immuno-PET or SPECT/CT imaging and biodistribution with ⁶⁴Cu-/¹⁷⁷Lu-cA10-A3 in various cholangiocarcinoma xenograft models. Therapeutic efficacy and response monitoring were performed by ¹⁷⁷Lu-cA10-A3 and ¹⁸F-FDG-PET, respectively, and immunohistochemistry was done by TUNEL and Ki-67.

RESULTS

Radiolabeled cA10-A3 antibodies specifically recognized L1CAM in vitro, clearly visualized cholangiocarcinoma tumors in immuno-PET and SPECT/CT imaging, and differentiated the L1CAM expression level in cholangiocarcinoma xenograft models. ¹⁷⁷Lu-cA10-A3 (12.95 MBq/100 μg) showed statistically significant reduction in tumor volumes (P < 0.05) and decreased glucose metabolism (P < 0.01). IHC analysis revealed ¹⁷⁷Lu-cA10-A3 treatment increased TUNEL-positive and decreased Ki-67-positive cells, compared with saline, cA10-A3, or ¹⁷⁷Lu-isotype.

CONCLUSIONS

Anti-L1CAM immuno-PET imaging using ⁶⁴Cu-cA10-A3 could be translated into the clinic for characterizing the pharmacokinetics and selecting appropriate patients for radioimmunotherapy. Radioimmunotherapy using ¹⁷⁷Lu-cA10-A3 may provide survival benefit in L1CAM-expressing cholangiocarcinoma tumor. Theranostic convergence bioradiopharmaceutical strategy would be applied as imaging biomarker-based personalized medicine in L1CAM-expressing patients with cholangiocarcinoma.

Prognostic value and clinicopathologic characteristics of L1 cell adhesion molecule (L1CAM) in a large series of vulvar squamous cell carcinomas

Background

Vulvar cancer treatment is mostly curative, but also has high morbidity rates. In a search for markers that can identify patients at risk of metastases, we investigated the prognostic value of L1-cell adhesion molecule (L1CAM) in large series of vulvar squamous cell carcinomas (VSCCs). L1CAM promotes cell motility and is an emerging prognostic factor for metastasis in many cancer subtypes.

Results

L1CAM expression was observed at the invasive front or in spray-patterned parts of 17% of the tumours. L1CAM-positive tumours expressed vimentin more often, but L1CAM expression was not associated with TP53 or CTNNB1 mutations. Five-year survival was worse for patients with L1CAM expression (overall survival 46.1% vs 63.6%, P=.014, disease specific survival 63.8% vs 80.0%, P=.018). Multivariate analysis indicates L1CAM expression as an independent prognostic marker (HR 2.9, 95% CI 1.10–7.68). An in vitro spheroid invasion assay showed decreased invasion of L1CAM-expressing VSCC spindle cells after treatment with L1CAM-neutralising antibodies.

Materials and Methods

Paraffin-embedded tumour tissue from two cohorts (N=103 and 245) of primary VSCCs were stained for L1CAM, vimentin and E-cadherin. Patients of the first cohort were tested for human papilloma virus infection and sequenced for TP53 and CTNNB1 (β-catenin) mutations. The expression of L1CAM was correlated to clinical characteristics and patient survival.

Conclusion

This is the first study to show high L1CAM-expression at the infiltrating margin of VSCC's. L1CAM-expressing VSCCs had a significantly worse prognosis compared to L1CAM-negative tumours. The highest expression was observed in spindle-shaped cells, where it might be correlated to their invasive capacity.

Expression of neural cell adhesion molecule L1 (CD171) in neuroectodermal and other tumors: An immunohistochemical study of 5155 tumors and critical evaluation of CD171 prognostic value in gastrointestinal stromal tumors

The neural cell adhesion molecule L1 (CD171) is a multidomain type 1 membrane glycoprotein of the immunoglobulin superfamily important in the nervous system development, kidney morphogenesis, and maintenance of the immune system. Recent studies reported CD171 expression being associated with adverse clinical outcome in different types of cancer and there has been a growing interest in targeting this cell membrane molecule on neoplastic cells by chimeric antigen receptor redirected T lymphocytes or specific antibodies. Nevertheless, conflicting results regarding the prognostic value of CD171 expression in renal cell carcinomas and gastrointestinal stromal tumors were published. In this study, CD171 expression was immunohistochemically analyzed in 5155 epithelial, mesenchymal, melanocytic, and lymphohematopoietic tumors to assess its utility in diagnostic pathology and to pinpoint potential targets for CD171-targeting therapy. A newly developed anti-CD171 rabbit monoclonal antibody, clone 014, was selected from the panel of commercially available CD171 antibodies. Immunohistochemistry was performed using Leica Bond Max automation and multitumor blocks containing up to 60 tumor samples. CD171 was constitutively and strongly expressed in neuroectodermal tumors such as schwannoma, neuroblastoma, and paraganglioma, whereas other mesenchymal tumors including schwannoma mimics showed only rarely CD171 positivity. Frequent CD171-expression was also detected in ovarian serous carcinoma, malignant mesothelioma, and testicular embryonal carcinoma. CD171 immunohistochemistry may have some role in immunophenotypic differential diagnosis of neurogenic tumors and pinpointing potential candidates for anti-CD171 therapy. Though, because of its rare expression and lack of predictive value, CD171 is neither a diagnostic nor prognostic marker for gastrointestinal stromal tumors.

L1CAM promotes epithelial to mesenchymal transition and formation of cancer initiating cells in human endometrial cancer

Identification of novel factors critical for epithelial to mesenchymal transition (EMT) and cancer initiating cell (CIC) formation may aid in the identification of novel therapeutics for the treatment of endometrial cancer. The present study demonstrated that L1 cell adhesion molecule (CAM) is critical for EMT and formation of CICs in endometrial cancer. Overexpression of L1CAM may promote EMT with increased formation of CICs in HEC-1A endometrial cancer cells. CICs and mesenchymal status resist chemotherapeutic drugs and may regenerate the various cell types in tumors, thereby resulting in relapse of the disease. The present study demonstrated that overexpressing L1CAM promoted paclitaxel resistance and regulated paclitaxel resistance-associated microRNA expression in HEC-1A cells. Furthermore, it was demonstrated that overexpressing L1CAM promoted anoikis resistance in HEC-1A cells. This link between L1CAM and EMT/CICs may provide a novel target for advancing anticancer therapy.

Transcriptomes of major renal collecting duct cell types in mouse identified by single-cell RNA-seq

Prior RNA sequencing (RNA-seq) studies have identified complete transcriptomes for most renal epithelial cell types. The exceptions are the cell types that make up the renal collecting duct, namely intercalated cells (ICs) and principal cells (PCs), which account for only a small fraction of the kidney mass, but play critical physiological roles in the regulation of blood pressure, extracellular fluid volume, and extracellular fluid composition. To enrich these cell types, we used FACS that employed well-established lectin cell surface markers for PCs and type B ICs, as well as a newly identified cell surface marker for type A ICs, c-Kit. Single-cell RNA-seq using the IC- and PC-enriched populations as input enabled identification of complete transcriptomes of A-ICs, B-ICs, and PCs. The data were used to create a freely accessible online gene-expression database for collecting duct cells. This database allowed identification of genes that are selectively expressed in each cell type, including cell-surface receptors, transcription factors, transporters, and secreted proteins. The analysis also identified a small fraction of hybrid cells expressing aquaporin-2 and anion exchanger 1 or pendrin transcripts. In many cases, mRNAs for receptors and their ligands were identified in different cells (e.g., Notch2 chiefly in PCs vs. Jag1 chiefly in ICs), suggesting signaling cross-talk among the three cell types. The identified patterns of gene expression among the three types of collecting duct cells provide a foundation for understanding physiological regulation and pathophysiology in the renal collecting duct.

Combination of anti-L1 cell adhesion molecule antibody and gemcitabine or cisplatin improves the therapeutic response of intrahepatic cholangiocarcinoma

Cholangiocarcinoma has a poor prognosis and is refractory to conventional chemotherapy and radiation therapy. Improving survival of patients with advanced cholangiocarcinoma urgently requires the development of new effective targeted therapies in combination with chemotherapy. We previously developed a human monoclonal antibody (mAb) Ab417 that binds to both the human and mouse L1 cell adhesion molecule (L1CAM) with high affinities. In the present study, we observed that Ab417 exhibited tumor targeting ability in biodistribution studies and dose-dependent tumor growth inhibition in an intrahepatic cholangiocarcinoma (Choi-CK) xenograft mouse model. Regarding the mechanism of action, Ab417 was internalized into the tumor cells and thereby down-regulated membrane L1CAM, and inhibited tumor growth by reducing tumor cell proliferation in vivo. Gemcitabine inhibited the tumor growth in a dose-dependent manner in the Choi-CK xenograft model. However, cisplatin inhibited the tumor growth moderately and not in a dose-dependent way, suggesting that the tumors may have developed resistance to apoptosis induced by cisplatin. Combined treatment with Ab417 and gemcitabine or cisplatin exerted enhanced tumor growth inhibition compared to treatment with antibody or drug alone. The results suggest that Ab417 in combination with chemotherapy may have potential as a new therapeutic regimen for cholangiocarcinoma. Our study is the first to show an enhanced therapeutic effect of a therapeutic antibody targeting L1CAM in combination with chemotherapy in cholangiocarcinoma models.

The Pleiotropic Role of L1CAM in Tumor Vasculature

Angiogenesis, the formation of new vessels, is a key step in the development, invasion, and dissemination of solid tumors and, therefore, represents a viable target in the context of antitumor therapy. Indeed, antiangiogenic approaches have given promising results in preclinical models and entered the clinical practice. However, in patients, the results obtained so far with antiangiogenic drugs have not completely fulfilled expectations, especially because their effect has been transient with tumors developing resistance and evasion mechanisms. A better understanding of the mechanisms that underlie tumor vascularization and the functional regulation of cancer vessels is a prerequisite for the development of novel and alternative antiangiogenic treatments. The L1 cell adhesion molecule (L1CAM), a cell surface glycoprotein previously implicated in the development and plasticity of the nervous system, is aberrantly expressed in the vasculature of various cancer types. L1CAM plays multiple pro-angiogenic roles in the endothelial cells of tumor-associated vessels, thus emerging as a potential therapeutic target. In addition, L1CAM prevents the maturation of cancer vasculature and its inhibition promotes vessel normalization, a process that is thought to improve the therapeutic response of tumors to cytotoxic drugs. We here provide an overview on tumor angiogenesis and antiangiogenic therapies and summarize the current knowledge on the biological role of L1CAM in cancer vasculature. Finally, we highlight the clinical implications of targeting L1CAM as a novel antiangiogenic and vessel-normalizing approach.

Mechanisms and Targets Involved in Dissemination of Ovarian Cancer

Ovarian carcinoma is associated with the highest death rate of all gynecological tumors. On one hand, its aggressiveness is based on the rapid dissemination of ovarian cancer cells to the peritoneum, the omentum, and organs located in the peritoneal cavity, and on the other hand, on the rapid development of resistance to chemotherapeutic agents. In this review, we focus on the metastatic process of ovarian cancer, which involves dissemination of, homing to and growth of tumor cells in distant organs, and describe promising molecular targets for possible therapeutic intervention. We provide an outline of the interaction of ovarian cancer cells with the microenvironment such as mesothelial cells, adipocytes, fibroblasts, endothelial cells, and other stromal components in the context of approaches for therapeutic interference with dissemination. The targets described in this review are discussed with respect to their validity as drivers of metastasis and to the availability of suitable efficient agents for their blockage, such as small molecules, monoclonal antibodies or antibody conjugates as emerging tools to manage this disease.

L1CAM in the Early Enteric and Urogenital System

L1 cell adhesion molecule (L1CAM) is a transmembrane molecule belonging to the L1 protein family. It has shown to be a key player in axonal guidance in the course of neuronal development. Furthermore, L1CAM is also crucial for the establishment of the enteric and urogenital organs and is aberrantly expressed in cancer originating in these organs. Carcinogenesis and embryogenesis follow a lot of similar molecular pathways, but unfortunately, comprehensive data on L1CAM expression and localization in human developing organs are lacking so far. In the present study we, therefore, examined the spatiotemporal distribution of L1CAM in the early human fetal period (weeks 8-12 of gestation) by means of immunohistochemistry and in situ hybridization (ISH). In the epithelia of the gastrointestinal organs, L1CAM localization cannot be observed in the examined stages most likely due to their advanced polarization and differentiation. Despite these results, our ISH data indicate weak L1CAM expression, but only in few epithelial cells. The genital tracts, however, are distinctly L1CAM positive throughout the entire fetal period. We, therefore, conclude that in embryogenesis L1CAM is crucial for further differentiation of epithelia.

CNS tau efflux via exosomes is likely increased in Parkinson's disease but not in Alzheimer's disease

INTRODUCTION

Alzheimer's disease (AD) and Parkinson's disease (PD) involve tau pathology. Tau is detectable in blood, but its clearance from neuronal cells and the brain is poorly understood.

METHODS

Tau efflux from the brain to the blood was evaluated by administering radioactively labeled and unlabeled tau intracerebroventricularly in wild-type and tau knock-out mice, respectively. Central nervous system (CNS)-derived tau in L1CAM-containing exosomes was further characterized extensively in human plasma, including by single molecule array technology with 303 subjects.

RESULTS

The efflux of Tau, including a fraction via CNS-derived L1CAM exosomes, was observed in mice. In human plasma, tau was explicitly identified within L1CAM exosomes. In contrast to AD patients, L1CAM exosomal tau was significantly higher in PD patients than controls and correlated with cerebrospinal fluid tau.

CONCLUSIONS

Tau is readily transported from the brain to the blood. The mechanisms of CNS tau efflux are likely different between AD and PD.

The Genetic Basis of Hydrocephalus

Studies of syndromic hydrocephalus have led to the identification of >100 causative genes. Even though this work has illuminated numerous pathways associated with hydrocephalus, it has also highlighted the fact that the genetics underlying this phenotype are more complex than anticipated originally. Mendelian forms of hydrocephalus account for a small fraction of the genetic burden, with clear evidence of background-dependent effects of alleles on penetrance and expressivity of driver mutations in key developmental and homeostatic pathways. Here, we synthesize the currently implicated genes and inheritance paradigms underlying hydrocephalus, grouping causal loci into functional modules that affect discrete, albeit partially overlapping, cellular processes. These in turn have the potential to both inform pathomechanism and assist in the rational molecular classification of a clinically heterogeneous phenotype. Finally, we discuss conceptual methods that can lead to enhanced gene identification and dissection of disease basis, knowledge that will potentially form a foundation for the design of future therapeutics.

L1 cell adhesion molecule as a therapeutic target in cancer

L1 cell adhesion molecule (L1CAM) is the prototype member of the L1-family of closely related neural adhesion molecules. L1CAM is differentially expressed in the normal nervous system as well as pathological tissues and displays a wide range of biological activities. In human malignancies, L1CAM plays a vital role in tumor growth, invasion and metastasis. Recently, increasing evidence has suggested that L1CAM exerts a variety of functions at different steps of tumor progression through a series of signaling pathways. In addition, L1CAM has been identified as a promising target for cancer therapy by using synthetic and natural inhibitors. In this review, we provide an up-to-date overview of the role of L1CAM involved in cancers and the rationale for L1CAM as a novel molecular target for cancer therapy.

Generation, characterization and preclinical studies of a human anti-L1CAM monoclonal antibody that cross-reacts with rodent L1CAM

L1 cell adhesion molecule (L1CAM) is aberrantly expressed in malignant tumors and plays important roles in tumor progression. Thus, L1CAM could serve as a therapeutic target and anti-L1CAM antibodies may have potential as anticancer agents. However, L1CAM is expressed in neural cells and the druggability of anti-L1AM antibody must be validated at the earliest stages of preclinical study. Here, we generated a human monoclonal antibody that is cross-reactive with mouse L1CAM and evaluated its pharmacokinetic properties and anti-tumor efficacy in rodent models. First, we selected an antibody (Ab4) that binds human and mouse L1CAM from the human naïve Fab library using phage display, then increased its affinity 45-fold through mutation of 3 residues in the complementarity-determining regions (CDRs) to generate Ab4M. Next, the affinity of Ab4M was increased 1.8-fold by yeast display of single-chain variable fragment containing randomly mutated light chain CDR3 to generate Ab417. The affinities (K_D) of Ab417 for human and mouse L1CAM were 0.24 nM and 79.16 pM, respectively. Ab417 specifically bound the Ig5 domain of L1CAM and did not exhibit off-target activity, but bound to the peripheral nerves embedded in normal human tissues as expected in immunohistochemical analysis. In a pharmacokinetics study, the mean half-life of Ab417 was 114.49 h when a single dose (10 mg/kg) was intravenously injected into SD rats. Ab417 significantly inhibited tumor growth in a human cholangiocarcinoma xenograft nude mouse model and did not induce any adverse effect in in vivo studies. Thus, Ab417 may have potential as an anticancer agent.

L1cam promotes tumor progression and metastasis and is an independent unfavorable prognostic factor in gastric cancer

Background

Previous reports have demonstrated that L1cam is aberrantly expressed in various tumors. The potential role of L1cam in the progression and metastasis of gastric cancer is still not clear and needs exploring.

Methods

Expression of L1cam was evaluated in gastric cancer tissues and cell lines by immunohistochemistry and Western blot. The relationship between L1cam expression and clinicopathological characteristics was analyzed. The effects of L1cam on cell proliferation, migration and invasion were investigated in gastric cancer cell lines both in vitro and in vivo. The impact of L1cam on PI3K/Akt pathway was also evaluated.

Results

L1cam was overexpressed in gastric cancer tissues and cell lines. L1cam expression was correlated with aggressive tumor phenotype and poor overall survival in gastric cancer patients. Ectopic expression of L1cam in gastric cell lines significantly promoted cell proliferation, migration and invasion whereas knockdown of L1cam inhibited cell proliferation, migration and invasion in vitro as well as tumorigenesis and metastasis in vivo. The low level of phosphorylated Akt in HGC27 cells was up-regulated after ectopic expression of L1cam, whereas the high level of phosphorylated Akt in SGC7901 cells was suppressed by knockdown of L1cam. Moreover, the migration and invasion promoted by L1cam overexpression in gastric cancer cells could be abolished by either application of LY294002 (a phosphoinositide-3-kinase inhibitor) or knockdown of endogenous Akt by small interfering RNA.

Conclusions

Our study demonstrated that L1cam, overexpressed in gastric cancer and associated with poor prognosis, plays an important role in the progression and metastasis of gastric cancer.

Illustration of extensive extracellular matrix at the epithelial-mesenchymal interface within the renal stem/progenitor cell niche

BACKGROUND

Stem/progenitor cells are promising candidates to treat diseased renal parenchyma. However, implanted stem/progenitor cells are exposed to a harmful atmosphere of degenerating parenchyma. To minimize hampering effects after an implantation investigations are in progress to administer these cells within an artificial polyester interstitum supporting survival. Learning from nature the renal stem/progenitor cell niche appears as a valuable model. At this site epithelial stem/progenitor cells within the collecting duct ampulla face mesenchymal stem/progenitor cells. Both cell types do not have close contact but are separated by a wide interstitium.

METHODS

To analyze extracellular matrix in this particular interstitium, special contrasting for transmission electron microscopy was performed. Kidneys of neonatal rabbits were fixed in solutions containing glutaraldehyde (GA) or in combination with cupromeronic blue, ruthenium red and tannic acid.

RESULTS

GA revealed a basal lamina at the ampulla and a bright but inconspicuously looking interstitial space. In contrast, GA containing cupromeronic blue exhibits numerous proteoglycan braces lining from the ampulla towards the interstitial space. GA containing ruthenium red or tannic acid demonstrates clouds of extracellular matrix protruding from the basal lamina of the ampulla to the surface of mesenchymal stem/progenitor cells.

CONCLUSIONS

The actual data show that the interstitium between epithelial and mesenchymal stem/progenitor cells contains much more and up to date unknown extracellular matrix than earlier observed by classical GA fixation.

Aberrant l1 cell adhesion molecule affects tumor behavior and chemosensitivity in anaplastic thyroid carcinoma

PURPOSE

Anaplastic thyroid carcinoma (ATC) is one of the most invasive human cancers and has a poor prognosis. Molecular targets of ATC that determine its highly aggressive nature remain unidentified. This study investigated L1 cell adhesion molecule (L1CAM) expression and its role in tumorigenesis of ATCs.

EXPERIMENTAL DESIGN

Expression of L1CAM in thyroid cancer was evaluated by immunohistochemical analyses of tumor samples from patients with thyroid cancer. We investigated the role of L1CAM in proliferation, migration, invasion, and chemoresistance using short hairpin RNA (shRNA) knockdown experiments in human ATC cell lines. Finally, we evaluated the role of L1CAM on tumorigenesis with ATC xenograft assay in a nude mouse model.

RESULTS

L1CAM expression was not detectable in normal follicular epithelial cells of the thyroid or in differentiated thyroid carcinoma. In contrast, analysis of ATC samples showed specifically higher expression of L1CAM in the invasive area of the tumor. Specific knockdown of L1CAM in the ATC cell lines, FRO and 8505C, caused a significant decrease in the proliferative, migratory, and invasive capabilities of the cells. Suppression of L1CAM expression in ATC cell lines increased chemosensitivity to gemcitabine or paclitaxel. Finally, in an ATC xenograft model, depletion of L1CAM markedly reduced tumor growth and increased the survival of tumor-bearing mice.

CONCLUSIONS

We report that L1CAM is highly expressed in the samples taken from patients with ATCs. L1CAM plays an important role in determining tumor behavior and chemosensitivity in cell lines derived from ATCs. Therefore, we suggest that L1CAM may be an important therapeutic target in patients with ATCs.

Peculiarities of the extracellular matrix in the interstitium of the renal stem/progenitor cell niche

The development of the nephron is piloted by interactions between epithelial and surrounding mesenchymal stem/progenitor cells. Data show that an astonishingly wide interstitial space separates both kinds of stem/progenitor cells. A simple contrasting procedure was applied to visualize features that keep renal epithelial and mesenchymal stem/progenitor cells in distance. The kidney of neonatal rabbits was fixed in solutions containing glutaraldehyde (GA) in combination with alcian blue, lanthanum, ruthenium red, or tannic acid. To obtain a comparable view to the renal stem/progenitor cell niche, the tissue was exactly orientated along the axis of collecting ducts. Fixation with GA or in combination with alcian blue or lanthanum revealed an inconspicuous interstitial space. In contrast, fixation with GA containing ruthenium red exhibits strands of extracellular matrix lining from epithelial stem/progenitor cells through the interstitium up to the surface of mesenchymal stem/progenitor cells. Fixation with GA containing tannic acid shows that the basal lamina of epithelial stem/progenitor cells, the adjacent interstitial space and also the surface of mesenchymal stem/progenitor cells are connected over a net of extracellular matrix. The applied technique appears to be a suitable method to illuminate the interstitium in stem/progenitor cell niches of specialized tissues, the microenvironment of tumors and extension of degeneration.

L1 cell adhesion molecule as a novel independent poor prognostic factor in gallbladder carcinoma

Gallbladder carcinoma is a lethal malignancy and is hard to cure by current treatment. Thus, identification of molecular prognostic markers to predict gallbladder carcinoma as therapeutic targets is urgently needed. Recent studies have demonstrated that L1 cell adhesion molecule is associated with the prognosis of variable malignancy. Here, we investigated L1 cell adhesion molecule expression in gallbladder carcinoma and its prognostic significance. In this study, we examined L1 cell adhesion molecule expression in tumor specimens from 69 patients with gallbladder carcinoma by immunohistochemistry and analyzed the correlation between L1 cell adhesion molecule expression and clinicopathologic factors or survival. L1 cell adhesion molecule was not expressed in the normal epithelium of the gallbladder but in 63.8% of gallbladder carcinomas, remarkably at the invasive front of the tumors. In addition, L1 cell adhesion molecule expression was significantly associated with high histologic grade, advanced pathologic T stage and clinical stage, and positive venous/lymphatic invasion. Multivariate analyses showed that L1 cell adhesion molecule expression (hazard ratio, 3.503; P = .028) and clinical stage (hazard ratio, 3.091; P = .042) were independent risk factor for disease-free survival. L1 cell adhesion molecule expression in gallbladder carcinoma was significantly correlated with tumor progression and unfavorable clinicopathologic features. L1 cell adhesion molecule expression was an independent poor prognostic factor for disease-free survival in patients with gallbladder carcinoma. Taken together, our findings suggest that L1 cell adhesion molecule expression could be used as a novel prognostic factor for patient survival and might be a potential therapeutic target in gallbladder carcinomas.

Structural mechanism of the antigen recognition by the L1 cell adhesion molecule antibody A10-A3

The L1CAM antibody A10-A3 efficiently reduces tumor growth in a nude mouse model. Here, we describe the crystal structure of the Fab fragment of A10-A3 determined at 2.0 angstrom resolution. The A10-A3 antibody H3 loop reveals a characteristic arrangement of exposed aromatic residues that may play an important role in antigen binding. A structure model of the complex between L1CAM Ig1-4 and A10-A3 Fab indicates that the Fab binds to three small loops outside Ig1 and a residue between Ig1 and Ig2, consistent with an epitope mapping result. The data presented here should contribute to the design of high-affinity antibody for therapeutic purposes as well as to the understanding of neural cell remodeling and cancer progression mechanism mediated by L1CAM.

Developmental changes of cell adhesion molecule expression in the fetal mouse liver

Developmental changes of cell adhesion molecule expression, especially in nonparenchymal cells, have hardly ever been analyzed in the murine liver. The present study was undertaken to immunohistochemically examine the expression of NCAM, ICAM, VCAM, and N-cadherin during mouse liver development and in fetal liver cell cultures. NCAM was transiently expressed in mesenchymal cells of the septum transversum and sinusoidal cells in liver development. In vitro studies demonstrated that desmin-positive stellate cells expressed this cell adhesion molecule. NCAM expression in periportal biliary epithelial cells and connective tissue cells also coincided well with bile duct remodeling processes in the perinatal periods. Expression of ICAM and VCAM was transiently restricted to hepatoblasts, hepatocytes and hemopoietic cells in fetal stages. N-cadherin was expressed not only in hepatoblasts and hepatocytes, but also in nonparenchymal cells such as endothelial cells, stellate cells and connective tissue cells, however the expression was weak. These results suggest that each cell adhesion molecule may play an important role during development in hepatic histogenesis, including hepatoblast/hepatocyte-stellate cell interactions, hemopoiesis, and bile duct morphogenesis.

L1CAM malfunction in the nervous system and human carcinomas

Research over the last 25 years on the cell adhesion molecule L1 has revealed its pivotal role in nervous system function. Mutations of the human L1CAM gene have been shown to cause neurodevelopmental disorders such as X-linked hydrocephalus, spastic paraplegia and mental retardation. Impaired L1 function has been also implicated in the aetiology of fetal alcohol spectrum disorders, defective enteric nervous system development and malformations of the renal system. Importantly, aberrant expression of L1 has emerged as a critical factor in the development of human carcinomas, where it enhances cell proliferation, motility and chemoresistance. This discovery promoted collaborative work between tumour biologists and neurobiologists, which has led to a substantial expansion of the basic knowledge about L1 function and regulation. Here we provide an overview of the pathological conditions caused by L1 malfunction. We further discuss how the available data on gene regulation, molecular interactions and posttranslational processing of L1 may contribute to a better understanding of associated neurological and cancerous diseases.

ADAM10 is expressed in human podocytes and found in urinary vesicles of patients with glomerular kidney diseases

Background

The importance of the Notch signaling in the development of glomerular diseases has been recently described. Therefore we analyzed in podocytes the expression and activity of ADAM10, one important component of the Notch signaling complex.

Methods

By Western blot, immunofluorescence and immunohistochemistry analysis we characterized the expression of ADAM10 in human podocytes, human urine and human renal tissue.

Results

We present evidence, that differentiated human podocytes possessed increased amounts of mature ADAM10 and released elevated levels of L1 adhesion molecule, one well known substrate of ADAM10. By using specific siRNA and metalloproteinase inhibitors we demonstrate that ADAM10 is involved in the cleavage of L1 in human podocytes. Injury of podocytes enhanced the ADAM10 mediated cleavage of L1. In addition, we detected ADAM10 in urinary podocytes from patients with kidney diseases and in tissue sections of normal human kidney. Finally, we found elevated levels of ADAM10 in urinary vesicles of patients with glomerular kidney diseases.

Conclusions

The activity of ADAM10 in human podocytes may play an important role in the development of glomerular kidney diseases.

L1 cell adhesion molecule is a novel independent poor prognostic factor of extrahepatic cholangiocarcinoma

PURPOSE

Cholangiocarcinomas (CC) are associated with poor survival, but diagnostic markers and therapeutic targets have not yet been elucidated. We previously found aberrant expression of L1 cell adhesion molecule in intrahepatic CC and a role for L1 in the progression of intrahepatic CC. Here, we analyzed L1 expression in extrahepatic CC (ECC) and evaluated its prognostic significance.

EXPERIMENTAL DESIGN

We examined L1 expression in tumors from 75 ECC patients by immunohistochemistry. We analyzed the correlations between L1 expression and clinicopathologic factors as well as patient survival.

RESULTS

L1 was not expressed in normal extrahepatic bile duct epithelium but was aberrantly expressed in 42.7% of ECC tumors. High expression of L1 was detected at the invasive front of tumors and was significantly associated with perineural invasion (P < 0.01). Univariate analysis indicated that various prognostic factors such as histologic grade 3, advanced pathologic T stage and clinical stage, perineural invasion, nodal metastasis, and high expression of L1 were risk factors predicting patient survival. Multivariate analyses done by Cox's proportional hazards model showed that high expression of L1 (hazard ratio, 2.171; 95% confidence interval, 1.162-4.055; P = 0.015) and nodal metastasis (hazard ratio, 2.088; 95% confidence interval, 1.159-3.764; P = 0.014) were independent risk factors for patient death.

CONCLUSIONS

L1 was highly expressed in 42.7% of ECC and its expression was significantly associated with perineural invasion. High expression of L1 and nodal metastasis were independent poor prognostic factors predicting overall survival in patients with ECC.

Stimulation of glioma cell motility by expression, proteolysis, and release of the L1 neural cell recognition molecule

Background

Malignant glioma cells are particularly motile and can travel diffusely through the brain parenchyma, apparently without following anatomical structures to guide their migration. The neural adhesion/recognition protein L1 (L1CAM; CD171) has been implicated in contributing to stimulation of motility and metastasis of several non-neural cancer types. We explored the expression and function of L1 protein as a stimulator of glioma cell motility using human high-grade glioma surgical specimens and established rat and human glioma cell lines.

Results

L1 protein expression was found in 17 out of 18 human high-grade glioma surgical specimens by western blotting. L1 mRNA was found to be present in human U-87/LacZ and rat C6 and 9L glioma cell lines. The glioma cell lines were negative for surface full length L1 by flow cytometry and high resolution immunocytochemistry of live cells. However, fixed and permeablized cells exhibited positive staining as numerous intracellular puncta. Western blots of cell line extracts revealed L1 proteolysis into a large soluble ectodomain (~180 kDa) and a smaller transmembrane proteolytic fragment (~32 kDa). Exosomal vesicles released by the glioma cell lines were purified and contained both full-length L1 and the proteolyzed transmembrane fragment. Glioma cell lines expressed L1-binding αvβ5 integrin cell surface receptors. Quantitative time-lapse analyses showed that motility was reduced significantly in glioma cell lines by 1) infection with an antisense-L1 retroviral vector and 2) L1 ectodomain-binding antibodies.

Conclusion

Our novel results support a model of autocrine/paracrine stimulation of cell motility in glioma cells by a cleaved L1 ectodomain and/or released exosomal vesicles containing L1. This mechanism could explain the diffuse migratory behavior of high-grade glioma cancer cells within the brain.

Cancer genomics identifies regulatory gene networks associated with the transition from dysplasia to advanced lung adenocarcinomas induced by c-Raf-1

BACKGROUND

Lung cancer is a leading cause of cancer morbidity. To improve an understanding of molecular causes of disease a transgenic mouse model was investigated where targeted expression of the serine threonine kinase c-Raf to respiratory epithelium induced initially dysplasia and subsequently adenocarcinomas. This enables dissection of genetic events associated with precancerous and cancerous lesions.

METHODOLOGY/PRINCIPAL FINDINGS

By laser microdissection cancer cell populations were harvested and subjected to whole genome expression analyses. Overall 473 and 541 genes were significantly regulated, when cancer versus transgenic and non-transgenic cells were compared, giving rise to three distinct and one common regulatory gene network. At advanced stages of tumor growth predominately repression of gene expression was observed, but genes previously shown to be up-regulated in dysplasia were also up-regulated in solid tumors. Regulation of developmental programs as well as epithelial mesenchymal and mesenchymal endothelial transition was a hall mark of adenocarcinomas. Additionally, genes coding for cell adhesion, i.e. the integrins and the tight and gap junction proteins were repressed, whereas ligands for receptor tyrosine kinase such as epi- and amphiregulin were up-regulated. Notably, Vegfr- 2 and its ligand Vegfd, as well as Notch and Wnt signalling cascades were regulated as were glycosylases that influence cellular recognition. Other regulated signalling molecules included guanine exchange factors that play a role in an activation of the MAP kinases while several tumor suppressors i.e. Mcc, Hey1, Fat3, Armcx1 and Reck were significantly repressed. Finally, probable molecular switches forcing dysplastic cells into malignantly transformed cells could be identified.

CONCLUSIONS/SIGNIFICANCE

This study provides insight into molecular pertubations allowing dysplasia to progress further to adenocarcinoma induced by exaggerted c-Raf kinase activity.

Immunohistochemical localization of barx2 in the developing fetal mouse submandibular glands

The development of mouse submandibular gland (SMG) begins at embryonic day 11.5-12 (E11.5-12), during which successive rounds of epithelial clefting and branching create complex epithelial tree-like structures. Homeobox genes regulate place-dependent morphogenesis, including epithelial-mesenchymal interactions, and control the expression patterns of signaling molecules. The Barx2 containing Homeobox exerts several key roles in development. Some studies have shown that the Barx2 plays important roles in the epithelial-mesenchymal interactions of organogenesis. However, the mechanisms of Barx2 associated with the development of SMG are obscure. In this study, we demonstrated for the first time the exact spatial and temporal Barx2 expression pattern in SMG epithelial tissue during development using immunohistochemical staining and Real-Time quantitative PCR. Barx2 was expressed in the nucleus of the epithelial cells located in the proliferative and differentiative regions of the developing SMG during the early development stages (E11.5-E13.5). After the E14.5-time period, the expression gradually decreased, and at E16.5, expression mostly disappeared despite the fact that evidence of cytodifferentiation, such as the appearance of proacinar cells, distinct lumen formation, and secretory products, was beginning to be observed. Results of Real-Time PCR demonstrated that the amount of Barx2 mRNA expression in SMG was maximal on E14.5, and gradually decreased by E18.5. These results indicate that Barx2 is associated with early stage epithelial tissue development, and can be a useful epithelial marker of the SMG during early developmental stages.

The intracellular interactions of the L1 family of cell adhesion molecules

The L1 family of CAMs (cell adhesion molecules) has long aroused the interest of researchers, but primarily the extracellular interactions of these proteins have been elucidated. More recently, attention has turned to the intracellular signalling potentiated by transmembrane proteins and the cytoplasmic proteins with which they can interact. The present review brings up to date the current body of published knowledge for the intracellular interactions of L1-CAM family proteins and the potential importance of these interactions for the mechanisms of L1-CAM action.

Diagnostic and prognostic markers for gastrointestinal stromal tumors in Norway

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor in the gastrointestinal tract. The diagnosis of GIST is based on histology together with a panel of immunohistochemical markers; the most important is KIT (CD117). A total of 434 cases of GISTs were confirmed by histology and immunohistochemistry, and incorporated into tissue microarrays. Validation of histological features as well as the prognostic value of two immunohistochemical biomarkers (p16 and L1) was assessed. High mitotic rate, large tumor size, nuclear atypia, and small bowel primary site were all validated as negative prognostic factors in GISTs. Expression of p16 was significantly correlated with unfavorable prognosis, whereas L1 expression was not.

The L1 cell adhesion molecule is a potential biomarker of human distal nephron injury in acute tubular necrosis

The L1 cell adhesion molecule (CD171) is a multidomain membrane glycoprotein of the immunoglobulin superfamily. We evaluated its expression in human acute kidney injury and assessed its use as a tissue and urinary marker of acute tubular injury. Using immunohistochemical studies with antibodies to the extracellular or cytoplasmic domains, we compared L1 expression in normal kidneys in 24 biopsies taken from patients with acute tubular necrosis. L1 was found at the basolateral and the lateral membrane in all epithelial cells of the collecting duct in the normal kidney except for intercalated cells. In acute tubular necrosis, L1 lost its polarized distribution being found in both the basolateral and apical domains of the collecting duct. Further, it was induced in thick ascending limb and distal tubule cells. Apically expressed L1 found only when the cytoplasmic domain antibody was used in biopsy specimens of patients with acute tubular necrosis. The levels of urinary L1, normalized for creatinine, were significantly higher in all 24 patients with acute tubular necrosis compared to five patients with prerenal azotemia or to six patients with other causes of acute kidney injury. Our study shows that a soluble form of human L1 can be detected in the urine of patients with acute tubular necrosis and that this may be a marker of distal nephron injury.

The L1 cell adhesion molecule as a target for radioimmunotherapy

Monoclonal antibodies directed against the L1 cell adhesion molecule were shown recently to inhibit growth of target tumor cells in vitro and the growth of tumor cells in vivo in nude mice. The biologic functions of L1 in tumor cells, which include growth-promoting activity linked to endocytosis and cellular processing of the L1 cell surface protein, make this protein an attractive target for antibodies. This update deals with recent results on L1 expression in normal tissues and in the tumors that were investigated until now. L1 expression outside of the nervous system is highly restricted to peripheral nerve bundles and kidney-collecting tubule cells. In tumors, L1 overexpression is not ubiquitous. It is prevalent in neuroblastomas and in malignant ovarian tumors, and is also found in certain subtypes of other nonneuroendocrine and nongynecologic tumors, such as renal-cell carcinomas. The structure of the L1 protein and what is known about its functional role in tumors will be described in this paper. L1 is not only a novel tumor marker, but it appears to have growth-promoting and antiapoptotic functions and may contribute to a more malignant phenotype. The preclinical studies and the clinical study to evaluate tumor-targeting properties and potential for therapy of radiolabeled anti-L1 antibodies will be described to date. Some of these studies underline the importance of L1 endocytosis for the targeting of radiolabeled antibodies.

L1CAM mutation in a boy with hydrocephalus and duplex kidneys

Mutations in the X-chromosomal gene (L1CAM) for cell adhesion molecule L1 are associated with a heterogeneous group of conditions that include agenesis of the corpus callosum, hydrocephalus, spastic paraplegia, adducted thumbs and mental retardation (L1-spectrum disease, CRASH or MASA syndrome). Although L1CAM is expressed during renal development and L1cam-deficient mice have congenital malformations of the kidney and the urinary tract, L1CAM mutations have not been associated with renal anomalies in men. We report on a boy with prenatally detected hydrocephalus. After his birth, bilateral duplex kidneys and ureters, with a unilateral mega-ureter serving a hydronephrotic upper pole, as well as agenesis of the corpus callosum, adducted thumbs, spasticity, and mental retardation were recognized, fulfilling the criteria of an L1-spectrum disease. Genetic testing of the patient and his mother identified a 2 bp deletion in the invariant splice consensus sequence of intron 18 of L1CAM, predicting a largely truncated or absent protein. At the age of 9 years, 7 years after heminephrectomy, the boy has normal renal function. This observation suggests that patients with L1CAM mutations may have renal abnormalities as seen in the L1cam-deficient mouse model. L1CAM might, therefore, also be considered a possible candidate gene for renal malformations.

Cell adhesion molecule L1 disrupts E-cadherin-containing adherens junctions and increases scattering and motility of MCF7 breast carcinoma cells

The first steps of invasion and metastasis include the dissociation of adherens junctions and the induction of migratory phenotype, through a program that resembles epithelial-mesenchymal transition (EMT). The L1 cell adhesion molecule, which is normally found primarily in the brain, was recently shown to be expressed in different types of cancer and to have tumor-promoting activity. We now find that L1 mediates EMT-like events in MCF7 breast carcinoma cells. MCF7 predominantly expresses the nonneuronal isoform of L1, as do 16 of 17 other cell lines derived from different types of cancer. L1 protein expression in MCF7 cells, which form E-cadherin-containing adherens junctions, is inversely related to cell density. Analysis of MCF7 cells with overexpression or knockdown of nonneuronal L1 isoform revealed that L1 expression leads to the disruption of adherens junctions and increases beta-catenin transcriptional activity. As a result, L1 expression promotes the scattering of epithelial cells from compact colonies. Expression of the full-length L1 protein, but not of its soluble extracellular moiety, increases the motility of the MCF7 epithelial monolayer in a wound-healing assay, in which L1 expression is preferentially observed and required in cells leading the movement of the monolayer. Based on these results, we propose a model for the role of L1 as a trigger of EMT-like events in transformed epithelial cells.