Transcriptomic analysis of glucosidase II beta subunit (GluIIß) knockout A549 cells reveals its roles in regulation of cell adhesion molecules (CAMs) and anti-tumor immunity

Glucosidase II beta subunit (GluIIß), encoded from PRKCSH, is a subunit of the glucosidase II enzyme responsible for quality control of N-linked glycoprotein folding and suppression of GluIIß led to inhibitory effect of the receptor tyrosine kinase (RTKs) activities known to be critical for survival and development of cancer. In this study, we investigated the effect of GluIIß knockout on the global gene expression of cancer cells and its impact on functions of immune cells. GluIIß knockout lung adenocarcinoma A549 cell line was generated using CRISPR/Cas9-based genome editing system and subjected to transcriptomic analysis. Among 23,502 expressed transcripts, 1068 genes were significantly up-regulated and 807 genes greatly down-regulated. The KEGG enrichment analysis showed significant down-regulation of genes related extracellular matrix (ECM), ECM-receptor interaction, cytokine-cytokine receptor interaction and cell adhesion molecules (CAMs) in GluIIß knockout cells. Of 9 CAMs encoded DEG identified by KEGG enrichment analysis, real time RT-PCR confirmed 8 genes to be significantly down-regulated in all 3 different GluIIß knockout clones, which includes cadherin 4 (CDH4), cadherin 2 (CDH2), versican (VCAN), integrin subunit alpha 4 (ITGA4), endothelial cell-selective adhesion molecule (ESAM), CD274 (program death ligand-1 (PD-L1)), Cell Adhesion Molecule 1 (CADM1), and Nectin Cell Adhesion Molecule 3 (NECTIN3). Whereas PTPRF (Protein Tyrosine Phosphatase Receptor Type F) was significantly decreased only in 1 out of 3 knockout clones. Microscopic analysis revealed distinctively different cell morphology of GluIIβ knockout cells with lesser cytoplasmic and cell surface area compared to parental A549 cells and non-targeted transfected cells.Further investigations revealed that Jurkat E6.1 T cells or human peripheral blood mononuclear cells (PBMCs) co-cultured with GluIIß knockout A549 exhibited significantly increased viability and tumor cell killing activity compared to those co-cultured with non-target transfected cells. Analysis of cytokine released from Jurkat E6.1 T cells co-cultured with GluIIß knockout A549 cells showed significant increased level of angiogenin and significant decreased level of ENA-78. In conclusion, knockout of GluIIß from cancer cells induced altered gene expression profile that improved anti-tumor activities of co-cultured T lymphocytes and PBMCs thus suppression of GluIIß may represent a novel approach of boosting anti-tumor immunity.

Cell adhesion molecule 1 expression in mycosis fungoides versus parapsoriasis versus inflammatory dermatosis: an immunohistochemical comparative study

Cell adhesion molecule 1 (CADM1) is one of the immunoglobulin super family adhesion molecules, that is proposed to contribute in the pathogenesis of various types of cutaneous T-cell lymphoma, including mycosis fungoides (MF). In this work, we decided to examine the immunohistochemical expression of CADM1 in MF specimens compared to premycotic parapsoriasis, benign inflammatory dermatosis and normal control skin specimens. 125 participants were enrolled (50 MF, 25 parapsoriasis, 25 inflammatory dermatosis, and 25 healthy controls). Patients were selected from the Outpatient Clinic of Dermatology and Venereology Department, Tanta University Hospitals. From all, 4 mm punch skin biopsies were taken and examined for CADM1 immunohistochemical expression. The current study revealed statistically significant upregulation of CADM1 expression in MF specimens in comparison to parapsoriasis, inflammatory dermatosis, and normal control specimens. Additionally, there was statistically significant positive correlation between CADM1 expression and progression of TNMB staging of MF disease. Therefore, it is possible to recommend CADM1 as a beneficial diagnostic immunohistochemical marker for differentiation between early stages of MF and both the premycotic parapsoriasis and benign inflammatory dermatosis. Moreover, it may be of value in early detection of neoplastic transformation of parapsoriasis as well as in assessment of MF progression.

Molecular characterization of the cytotoxic and regulatory T cell coreceptor (CRTAM), and its ligand CADM1, in the European seabass and gilthead seabream

T cell activation is a multifaceted process that depends on the activation of the T cell receptor (TCR). However, other coreceptors are also strictly necessary to provide co-signals and modulate the immune response. However, to date, most of these coreceptors are unknown in fish or their information is very limited. Therefore, in this work, we have identified the cytotoxic and regulatory T cell molecule, CRTAM, and its ligand, the cell adhesion molecule 1, CADM1, in European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata); and evaluated their transcriptional levels. Both putative proteins showed the canonical architecture observed in mammals, where CRTAM exhibited two immunoglobulin domains and CADM1, both the a and b forms, exhibited three of these domains. In addition, phylogeny and synteny analyses showed their conservation throughout vertebrate evolution. We found constitutive expression of all three genes, with crtam and cadm1a being predominant in immune tissues such as spleen, thymus and head-kidney (HK), while cadm1b expression was more limited to the brain. In vitro, only the T cell mitogen phytohemagglutinin (PHA) up-regulated the transcription of crtam and cadm1a in HK leucocytes. Nodavirus (NNV) infection elicited an up-regulation of crtam and cadm1a in brain and HK, appearing earlier in seabream than in seabass, which could explain the resistance of seabream to the development of nodavirus disease. In addition, they are up-regulated during the innate cell-mediated cytotoxic response in seabream but not in seabass. Altogether, our data seem to indicate that CRTAM is more related to the innate cytotoxicity in seabream and more in the specific and T cell-mediated cytotoxicity in seabass. Our results highlight the importance of CRTAM and CADM1 as important molecules in the activation of T lymphocytes in seabass and seabream, but further studies are needed.

HAS-Flow May Be an Adequate Method for Evaluating Human T-Cell Leukemia Virus Type 1 Infected Cells in Human T-Cell Leukemia Virus Type 1-Positive Rheumatoid Arthritis Patients Receiving Antirheumatic Therapies: A Retrospective Cross-Sectional Observation Study

The study aims to assess the usefulness of human T-cell leukemia virus type 1 (HTLV-1)-infected cell analysis using flow cytometry (HAS-Flow) as a monitoring method for adult T-cell leukemia (ATL) development in HTLV-1-positive patients with rheumatoid arthritis (RA) under treatment with antirheumatic therapies. A total of 13 HTLV-1-negative and 57 HTLV-1-positive RA patients participated in this study, which was used to collect clinical and laboratory data, including HAS-Flow and HTLV-1 proviral load (PVL), which were then compared between the two groups. CADM1 expression on CD4+ cells in peripheral blood (PB) was used to identify HTLV-1-infected cells. The population of CADM1+ CD4+ cells was significantly higher in HTLV-1-positive RA patients compared to HTLV-1-negative RA patients. The population of CADM1+ CD4+ cells was correlated with HTLV-1 PVL values. There were no antirheumatic therapies affecting both the expression of CADM1 on CD4+ cells and PVLs. Six HTLV-1-positive RA patients who indicated both high HTLV-1 PVL and a predominant pattern of CADM1+ CD7neg CD4+ cells in HAS-Flow can be classified as high-risk for ATL progression. HAS-Flow could be a useful method for monitoring high-risk HTLV-1-positive RA patients who are at risk of developing ATL during antirheumatic therapies.

Phellopterin cream exerts an anti-inflammatory effect that facilitates diabetes-associated cutaneous wound healing via SIRT1

BACKGROUND

Diabetic ulcers, which are characterized by chronic nonhealing wounds with a long-lasting inflammatory state, are a typical symptom in individuals with diabetes, and there is still no effective treatment for these lesions. Angelica dahurica plays a critical role in inflammatory diseases. Among numerous monomeric compounds, phellopterin has been shown to have anti-inflammatory properties.

PURPOSE

To research the bioactive constituents in Angelica dahurica and their mechanism of action in treating diabetic ulcers.

STUDY DESIGN

Chemical research of Angelica dahurica led to the identification of a new coumarin, dahuricoumarin A (1), along with seven known compounds (2 - 8). All compounds were tested for anti-inflammatory activity, and phellopterin, compound (3), significantly decreased the expression of intercellular cell adhesion molecule-1 (ICAM-1), a representative indicator of inflammation. Phellopterin can also increase SIRT1 protein, a key target for inflammation. In our research, we confirmed the anti-inflammatory effects of phellopterin on diabetic ulcers and explored the underlying mechanism of action.

METHODS

The expression of IFN-γ, SIRT1, and ICAM-1 in human diabetic ulcer tissues was studied using immunohistochemistry. Streptozotocin was used to induce a diabetic model in C57BL/6J mice, and ulcers were surgically introduced. After phellopterin treatment, the skin lesions of diabetic mice were observed over a period of time. The protein and mRNA expression levels of SIRT1 and ICAM-1 were measured using H&E, qRT-PCR and immunohistochemical staining. A HaCaT cell inflammatory model was induced by IFN-γ. Using a lentiviral packaging technique, MTT assay, and Western blotting, the effect of phellopterin on the proliferation of HaCaT cells and the expression of ICAM-1 was evaluated under normal and SIRT1 knockdown conditions.

RESULTS

High levels of ICAM-1 and IFN-γ were identified, but low levels of SIRT1 were found in human diabetic ulcer tissues, and phellopterin showed therapeutic benefits in the healing process by attenuating chronic inflammation and promoting re-epithelialization, along with SIRT1 upregulation and ICAM-1 downregulation. However, inhibiting SIRT1 reversed its proliferative and anti-inflammatory effects.

CONCLUSION

In vitro and in vivo, phellopterin exerts anti-inflammatory and proliferative effects that promote diabetic wound healing, and the potential mechanism depends on SIRT1.

Exploring the angiographic-biologic phenotype in the IMAGINE study: quantitative UWFA and cytokine expression

BACKGROUND

This study investigates the association of intraocular cytokine expression and ultrawide-field fluorescein angiography (UWFA) quantitative imaging biomarkers and their association with angiographical feature response after antivascular endothelial growth factor (VEGF) therapy in diabetic macular oedema (DME).

METHODS

The IMAGINE DME study is a post hoc imaging biomarker and intraocular cytokine assessment from the DAVE study, a prospective DME clinical trial that included aqueous humour sampling and UWFA imaging. Fifty-four cytokines associated with inflammation and angiogenesis were evaluated through multiplex arrays. UWFA parameters were assessed using an automated feature analysis platform to determine ischaemic and leakage indices and microaneurysm (MA) count. Eyes were classified into UWFA responder or non-responder groups based on longitudinal quantitative UWFA parameter improvement. Cytokine expression was correlated with UWFA metrics and evaluated in the context of therapeutic response.

RESULTS

Twenty-one eyes were included with a mean age of 55±10 years. Increased panretinal leakage index correlated with VEGF (r=0.70, p=0.0005), angiopoietin-like 4 (r=0.77, p=4.6E-5) and interleukin (IL)-6 (r=0.64, p=0.002). Panretinal ischaemic index was associated with tissue inhibitor of metalloproteinases 1 (TIMP-1, r=0.49, p=0.03) and peripheral ischaemia correlated with VEGF (r=0.45, p=0.05). MA count correlated with increased monocyte chemotactic protein-4 (MCP-4, r=0.60, p=0.004) and platelet and endothelial cell adhesion molecule 1 (PECAM-1, r=0.58, p=0.005). Longitudinal MA reduction was associated with decreased baseline VEGF and urokinase receptor (uPAR) (p<0.05). High baseline VEGF and IL-6 were associated with dramatic reduction in macular leakage (p<0.05).

CONCLUSIONS

Baseline and longitudinal quantitative UWFA imaging parameters correlated with multiple aqueous humour cytokine concentrations, including VEGF and IL-6. Further research is needed to assess the possible implications of using these findings for evaluating treatment response.

Non-typeable Haemophilus influenzae airways infection: the next treatable trait in asthma?

Asthma is a complex, heterogeneous condition that affects over 350 million people globally. It is characterised by bronchial hyperreactivity and airways inflammation. A subset display marked airway neutrophilia, associated with worse lung function, higher morbidity and poor response to treatment. In these individuals, recent metagenomic studies have identified persistent bacterial infection, particularly with non-encapsulated strains of the Gram-negative bacterium Haemophilus influenzae. Here we review knowledge of non-typeable H. influenzae (NTHi) in the microbiology of asthma, the immune consequences of mucosal NTHi infection, various immune evasion mechanisms, and the clinical implications of NTHi infection for phenotyping and targeted therapies in neutrophilic asthma. Airway neutrophilia is associated with production of neutrophil chemokines and proinflammatory cytokines in the airways, including interleukin (IL)-1β, IL-6, IL-8, IL-12, IL-17A and tumour necrosis factor. NTHi adheres to and invades the lower respiratory tract epithelium, inducing the NLR family pyrin domain containing 3 (NLRP3) and absent in melanoma 2 (AIM2) inflammasomes. NTHi reduces expression of tight-junction proteins, impairing epithelial integrity, and can persist intracellularly. NTHi interacts with rhinoviruses synergistically via upregulation of intracellular cell adhesion molecule 1 and promotion of a neutrophilic environment, to which NTHi is adapted. We highlight the clinical relevance of this emerging pathogen and its relevance for the efficacy of long-term macrolide therapy in airways diseases, we identify important unanswered questions and we propose future directions for research.

MicroRNA-21: A Critical Pathogenic Factor of Diabetic Nephropathy

Diabetic nephropathy (DN), one of the most common and intractable microvascular complications of diabetes, is the main cause of terminal renal disease globally. MicroRNA-21 (miR-21) is a kind of miRNA early identified in human circulation and tissues. Mounting studies have demonstrated that miR-21 plays an important role in the development and progression of DN. This collaborative review aimed to present a first attempt to capture the current evidence on the relationship between miR-21 and DN. After a systematic search, 29 relevant studies were included for comprehensively and thoroughly reviewing. All these eligible studies reported that miR-21 was up-regulated in DN, whether in serum or renal tissues of human or animal models. MiR-21 exhibited its pathogenic roles in DN by forming a complex network with targeted genes (e.g. MMP-9, Smad7, TIMP3, Cdk6, FOXO1, IMP3, and MMP2) and the signaling cascades (e.g. Akt/TORC1 signaling axis, TGF-β/NF-κB signaling pathways, TGF-β/SMAD pathway, CADM1/STAT3 signaling, and AGE-RAGE regulatory cascade), which resulted in epithelial-to-mesenchymal transition, extracellular matrix deposition, cytoskeletal remodeling, inflammation, and fibrosis. This review highlights that miR-21 is a pivotal pathogenic factor in the development of DN. It may serve as an attractive potential diagnostic, prognostic, and predictive biomarker for DN in clinical practice after further confirmation of the clinicopathological features and molecular mechanisms of miR-21-mediated DN.

Carcinoembryonic antigen-related cell adhesion molecule 1: a key regulatory protein involved in leiomyoma growth

OBJECTIVE

To assess and characterize the role of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) in the development of uterine leiomyoma.

DESIGN

Laboratory study.

SETTING

Academic research center.

PATIENT(S)

Not applicable.

INTERVENTION(S)

Laboratory investigation. In vitro assessment of human leiomyoma and myometrial tissue specimens as well as immortalized leiomyoma and myometrial cell lines.

MAIN OUTCOME MEASURE(S)

Western blotting and immunohistochemical analyses were performed to assess differences in CEACAM1 content between leiomyoma and myometrial samples. Small interfering RNA silencing experiments and transient transfection experiments were performed to characterize the regulatory role of CEACAM1 on downstream signaling cascades.

RESULT(S)

Analysis of RNA sequencing data revealed decreased CEACAM1 expression in human uterine leiomyoma specimens compared with that in myometrial samples. This translated to a significant down-regulation in CEACAM1 protein content in human leiomyoma compared with patient-matched myometrial tissue samples (0.236 ± 0.05-fold). A similar decrease in CEACAM1 protein content was observed in matched immortalized leiomyoma cell (ILC) and immortalized myometrial cell lines (0.21 ± 0.07). Immunohistochemical analysis revealed decreased staining intensity in leiomyoma surgical specimens compared with the matched myometrium of placebo patients. Lower CEACAM1 levels in leiomyoma were associated with increased activation of both the mitogen-activated protein kinase (MAPK) and the phosphoinositide 3-kinase/protein kinase B pathways compared with that in myometrial cells. This is significant because activation of these pathways plays an important role in leiomyoma growth. Treatment of myometrial cells with CEACAM1 small interfering RNA resulted in a significant down-regulation of CEACAM1 at the protein level (0.272 ± 0.06-fold) and was associated with increased activation of the MAPK (1.62 ± 0.21-fold) and phosphoinositide 3-kinase/protein kinase B (1.79 ± 0.35-fold) pathways, as well as increased collagen production (2.1 ± 0.49-fold). Rescue of CEACAM1 expression in leiomyoma cells by transient transfection restored regulatory control and resulted in lower activation of the MAPK pathway (0.58 ± 0.37-fold).

CONCLUSION(S)

CEACAM1 is an important protein involved in regulating many signal transduction pathways. Decreased CEACAM1 expression in leiomyoma allows permissive uncontrolled overactivation and up-regulation of downstream pathways that may contribute to leiomyoma growth.

CEACAM1 and molecular signaling pathways to expand the liver transplant donor pool

Organ shortage continues to limit the lives of patients who require liver transplantation. While extending criteria for liver organs provides a needed resource, tissue damage from prolonged ischemic injury can result in early allograft dysfunction and consequent rejection. In this issue of the JCI, Nakamura et al. used a mouse transplantation model with prolonged ex vivo cold storage to explore liver graft protection. The authors found that liver grafts with absent carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) exhibited increased ischemia-reperfusion injury inflammation and decreased function in wild-type recipients. The authors went on to correlate CEACAM1 levels with postreperfusion damage in human liver transplant recipients. Notably, this study identified a potential biomarker for liver transplant donor graft quality.

[Role of vitamin K-dependent protein Gas6 in the expression of endothelial cell adhesion molecule-1 and chemokines induced by Porphyromonas gingivalis lipopolysaccharide]

OBJECTIVE

Growth-arrest-specific protein 6 (Gas6) is a vitamin K-dependent protein and involved in cell proliferation, survival, adhesion and migration . Also it has been shown to play an important role in the inflammatory response .The aim of present study was to investigate the role of Gas6 in the process of the expression of adhesion molecules and chemokines of human umbilical vein endothelial cells (HUVECs) induced by Porphyromonas gingivalis lipopolysaccharide(P.g-LPS).

METHODS

After up-regulation and down-regulation of the expression of Gas6, the vascular endothelial cells were stimulated with 1 mg/L P.g-LPS for 3 h and 24 h. Real-time quantitative polymerase chain reaction(real-time PCR) was taken to detect the expression of the cell adhesion molecules:intercellular adhesion molecule-1 (ICAM-1) and E-selectin, as well as chemokines:interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1). Wound healing assay was taken to observe the migration ability of endothelium cells in different groups.

RESULTS

After 3 h of P.g-LPS stimulation, the expression of adhesion molecules and chemokine in the down-regulation group was not significantly different from that in the control group,while in the up-regulation group the decrease of E-selectin, ICAM-1, IL-8 and MCP-1 was 81%±0%, 47%±3%, 76% ± 3%, 26% ± 6% respectively. After 24 h of P.g-LPS stimulation, the expression of adhesion molecules and chemokine in down-regulation group was significantly higher than that in control group (2.06±0.07, 1.99±0.11, 3.14±0.15, 1.84±0.03 flod), while these molecules in the down-regulation group was significantly lower than in the control group (29%±1%, 62%±3%, 69%±1%, 41%±2%). Differences were statistically significant (P<0.01). Wounding healing assay showed that down-regulation of Gas6 enhanced migration ability of endothelial cells while up-regulation of Gas6 weakened this ability,which was consistent with the trend of real-time PCR result.

CONCLUSION

Down-regulation of the Gas6 gene enhanced the expression of ICAM-1, E-selectin, IL-8 and MCP-1 in HUVECs after P.g- LPS stimulating, while up-regulaiton of the Gas6 gene weakened the expression of ICAM-1, E-selectin, IL-8 and MCP-1 in HUVECs after P.g-LPS stimulating,suggesting that Gas6 may play a role in the process of endothelial cell adhesion.

DNA methylation signatures and coagulation factors in the peripheral blood leucocytes of epithelial ovarian cancer

Solid tumors are increasingly recognized as a systemic disease that is manifested by changes in DNA, RNA, proteins and metabolites in the blood. Whereas many studies have reported gene mutation events in the circulation, few studies have focused on epigenetic DNA methylation markers. To identify DNA methylation biomarkers in peripheral blood for ovarian cancer, we performed a two-stage epigenome-wide association study. In the discovery stage, we measured genome wide DNA methylation for 485 000 CpG sites in peripheral blood in 24 epithelial ovarian cancer (EOC) cases and 24 age-matched healthy controls. We selected 96 significantly differentially methylated CpG sites for validation using Illumina's Custom VeraCode methylation assay in 206 EOC cases and 205 controls and 46 CpG sites validated in the independent replication samples. A set of 6 of these 46 CpG sites was found by the receiver operating characteristic analysis to have a prediction accuracy of 77.3% for all EOC (95% confidence interval: 72.9-81.8%). Pathway analysis of the genes associated with the 46 CpG sites revealed an enrichment of immune system process genes, including LYST (cg16962115, FDR = 1.24E-04), CADM1 (cg21933078, FDR = 1.22E-02) and NFATC1 (cg06784563, FDR = 1.46E-02). Furthermore, DNA methylation status in peripheral blood was correlated with platelet parameters/coagulation factor levels. This study discovered a panel of epigenetic liquid biopsy markers closely associated with overall immunologic conditions and platelet parameters/coagulation systems of the patients for detection of all stages and subtypes of EOC.

Manifestation of osteoblastic phenotypes in the sarcomatous component of epithelial carcinoma and sarcomatoid carcinoma

Epithelial carcinomas occasionally have sarcomatous components that consist primarily of spindle and cuboidal cells, which often resemble osteoblasts. Sarcomatoid carcinomas consist of similar cells. Recent studies have characterized these phenomena as a manifestation of epithelial-mesenchymal transition in carcinoma cells, but the mesenchymal phenotypes that manifest in sarcomatous cells of epithelial carcinomas are not well understood. Here, we examined the expression profiles of four osteoblastic differentiation biomarkers in the sarcomatous components of multiple carcinoma types, including five renal clear cell, four breast invasive ductal, two esophageal, one maxillary squamous cell, three larynx, three lung, one liver, and one skin sarcomatoid carcinoma. Expression was analyzed by immunohistochemistry using antibodies against cell adhesion molecule 1, a member of the IgCAM superfamily, osterix transcription factor (Osterix), cluster of differentiation 151, a transmembrane 4 superfamily member, and alkaline phosphatase. Immunostaining intensity was rated in scale 0 (negative), 0.5 (weak), and 1 (strong) for each marker, and the four scale values were summed to calculate osteoblastic scores. In all, 10 cases had a osteoblastic score ≥3, and all of these 10 cases were cell adhesion molecule 1- and Osterix-positive. Eight and five of the nine samples with a osteoblastic score <3 were negative for cell adhesion molecule 1 ( p < 0.0001) and Osterix ( p = 0.006), respectively. The other markers showed no statistical significance. These results indicate that osteoblastic differentiation can occur in carcinoma cells and that cell adhesion molecule 1 could be a useful marker for identifying this phenomenon in carcinoma tissues.

Negative feedback loop of bone resorption by NFATc1-dependent induction of Cadm1

Trimethylation of histone H3 lysine 4 and lysine 27 (H3K4me3 and H3K27me3) at gene promoter regions critically regulates gene expression. Key developmental genes tend to exhibit changes in histone modification patterns from the H3K4me3/H3K27me3 bivalent pattern to the H3K4me3 monovalent pattern. Using comprehensive chromatin immunoprecipitation followed by sequencing in bone marrow-derived macrophages (BMMs) and mature osteoclasts, we found that cell surface adhesion molecule 1 (Cadm1) is a direct target of nuclear factor of activated T cells 1 (NFATc1) and exhibits a bivalent histone pattern in BMMs and a monovalent pattern in osteoclasts. Cadm1 expression was upregulated in BMMs by receptor activator of nuclear factor kappa B ligand (RANKL), and blocked by a calcineurin/NFATc1 inhibitor, FK506. Cadm1-deficient mice exhibited significantly reduced bone mass compared with wild-type mice, which was due to the increased osteoclast differentiation, survival and bone-resorbing activity in Cadm1-deficient osteoclasts. These results suggest that Cadm1 is a direct target of NFATc1, which is induced by RANKL through epigenetic modification, and regulates osteoclastic bone resorption in a negative feedback manner.

Excitatory Synaptic Drive and Feedforward Inhibition in the Hippocampal CA3 Circuit Are Regulated by SynCAM 1

Select adhesion proteins control the development of synapses and modulate their structural and functional properties. Despite these important roles, the extent to which different synapse-organizing mechanisms act across brain regions to establish connectivity and regulate network properties is incompletely understood. Further, their functional roles in different neuronal populations remain to be defined. Here, we applied diffusion tensor imaging (DTI), a modality of magnetic resonance imaging (MRI), to map connectivity changes in knock-out (KO) mice lacking the synaptogenic cell adhesion protein SynCAM 1. This identified reduced fractional anisotropy in the hippocampal CA3 area in absence of SynCAM 1. In agreement, mossy fiber refinement in CA3 was impaired in SynCAM 1 KO mice. Mossy fibers make excitatory inputs onto postsynaptic specializations of CA3 pyramidal neurons termed thorny excrescences and these structures were smaller in the absence of SynCAM 1. However, the most prevalent targets of mossy fibers are GABAergic interneurons and SynCAM 1 loss unexpectedly reduced the number of excitatory terminals onto parvalbumin (PV)-positive interneurons in CA3. SynCAM 1 KO mice additionally exhibited lower postsynaptic GluA1 expression in these PV-positive interneurons. These synaptic imbalances in SynCAM 1 KO mice resulted in CA3 disinhibition, in agreement with reduced feedforward inhibition in this network in the absence of SynCAM 1-dependent excitatory drive onto interneurons. In turn, mice lacking SynCAM 1 were impaired in memory tasks involving CA3. Our results support that SynCAM 1 modulates excitatory mossy fiber inputs onto both interneurons and principal neurons in the hippocampal CA3 area to balance network excitability.

SIGNIFICANCE STATEMENT

This study advances our understanding of synapse-organizing mechanisms on two levels. First, the data support that synaptogenic proteins guide connectivity and can function in distinct brain regions even if they are expressed broadly. Second, the results demonstrate that a synaptogenic process that controls excitatory inputs to both pyramidal neurons and interneurons can balance excitation and inhibition. Specifically, the study reveals that hippocampal CA3 connectivity is modulated by the synapse-organizing adhesion protein SynCAM 1 and identifies a novel, SynCAM 1-dependent mechanism that controls excitatory inputs onto parvalbumin-positive interneurons. This enables SynCAM 1 to regulate feedforward inhibition and set network excitability. Further, we show that diffusion tensor imaging is sensitive to these cellular refinements affecting neuronal connectivity.

New Developments in Mast Cell Biology: Clinical Implications

Mast cells (MCs) are present in connective tissue and at mucosal surfaces in all classes of vertebrates. In health, they contribute to tissue homeostasis, host defense, and tissue repair via multiple receptors regulating the release of a vast stockpile of proinflammatory mediators, proteases, and cytokines. However, these potentially protective cells are a double-edged sword. When there is a repeated or long-term stimulus, MC activation leads to tissue damage and dysfunction. Accordingly, MCs are implicated in the pathophysiologic aspects of numerous diseases covering all organs. Understanding the biology of MCs, their heterogeneity, mechanisms of activation, and signaling cascades may lead to the development of novel therapies for many diseases for which current treatments are lacking or are of poor efficacy. This review will focus on updates and developments in MC biology and their clinical implications, with a particular focus on their role in respiratory diseases.

Extracellular CADM1 interactions influence insulin secretion by rat and human islet β-cells and promote clustering of syntaxin-1

Contact between β-cells is necessary for their normal function. Identification of the proteins mediating the effects of β-cell-to-β-cell contact is a necessary step toward gaining a full understanding of the determinants of β-cell function and insulin secretion. The secretory machinery of the β-cells is nearly identical to that of central nervous system (CNS) synapses, and we hypothesize that the transcellular protein interactions that drive maturation of the two secretory machineries upon contact of one cell (or neural process) with another are also highly similar. Two such transcellular interactions, important for both synaptic and β-cell function, have been identified: EphA/ephrin-A and neuroligin/neurexin. Here, we tested the role of another synaptic cleft protein, CADM1, in insulinoma cells and in rat and human islet β-cells. We found that CADM1 is a predominant CADM isoform in β-cells. In INS-1 cells and primary β-cells, CADM1 constrains insulin secretion, and its expression decreases after prolonged glucose stimulation. Using a coculture model, we found that CADM1 also influences insulin secretion in a transcellular manner. We asked whether extracellular CADM1 interactions exert their influence via the same mechanisms by which they influence neurotransmitter exocytosis. Our results suggest that, as in the CNS, CADM1 interactions drive exocytic site assembly and promote actin network formation. These results support the broader hypothesis that the effects of cell-cell contact on β-cell maturation and function are mediated by the same extracellular protein interactions that drive the formation of the presynaptic exocytic machinery. These interactions may be therapeutic targets for reversing β-cell dysfunction in diabetes.

CADM1/TSLC1 Identifies HTLV-1-Infected Cells and Determines Their Susceptibility to CTL-Mediated Lysis

Human T cell lymphotropic virus-1 (HTLV-1) primarily infects CD4⁺ T cells, causing inflammatory disorders or a T cell malignancy in 5% to 10% of carriers. The cytotoxic T lymphocyte (CTL) response is a key factor that controls the viral load and thus the risk of disease. The ability to detect the viral protein Tax in primary cells has made it possible to estimate the rate at which Tax-expressing infected cells are eliminated by CTLs in persistently infected people. However, most HTLV-1-infected cells are Tax^–at a given time, and their immunophenotype is poorly defined. Here, we aimed to identify a cell-surface molecule expressed by both Tax⁺ and Tax^–HTLV-1-infected cells and use it to analyse the CTL response in fresh peripheral blood mononuclear cells. Cell adhesion molecule 1 (CADM1/TSLC1) was the best single marker of HTLV-1 infection, identifying HTLV-1-infected cells with greater sensitivity and specificity than CD25, CCR4 or ICAM-1. CADM1⁺CD4⁺ T cells carried a median of 65% of proviral copies in peripheral blood. In a cohort of 23 individuals, we quantified the rate of CTL-mediated killing of Tax⁺ and Tax⁻CADM1⁺ cells. We show that CADM1 expression is associated with enhanced susceptibility of infected cells to CTL lysis: despite the immunodominance of Tax in the CTL response, Tax⁺CADM1^– cells were inefficiently lysed by CTLs. Upregulation of the CADM1 ligand CRTAM on CD8⁺ T cells correlated with efficient lysis of infected cells. Tax^–CADM1⁺ cells were lysed at a very low rate by autologous CTLs, however, were efficiently killed when loaded with exogenous peptide antigen. High expression of CADM1 on most HTLV-1-infected cells in the face of enhanced CTL counterselection implies that CADM1 confers a strong benefit on the virus.

Human T cell lymphotropic virus-1 (HTLV-1) infects white blood cells (CD4⁺ T cells) for the lifetime of the host. The immune response limits viral spread, and people with a weak immune response have a high risk of developing an aggressive blood cancer, or a condition involving irreversible spinal cord damage. Virus and host are engaged in a constant battle: virus proteins drive the host cell to divide or infect new cells. We know that the viral protein Tax is an important target of the immune response, and cells which produce Tax are killed quickly. Infected cells which do not produce Tax are difficult to detect, so we have no idea how quickly they are killed. In this paper we show that most infected cells have a host protein ‘CADM1’ on their surface. We measured killing of CADM1 cells and saw that Tax⁺CADM1⁺ cells are the only infected cells which are strongly targeted by the immune response. We also found that infected cells which did not have CADM1 on the surface escaped killing, showing that CADM1 aids in immune control of HTLV-1. These findings are an important step forward in our understanding of cellular turnover and immune control in chronic infection.

Topographic Mapping of the Synaptic Cleft into Adhesive Nanodomains

The cleft is an integral part of synapses, yet its macromolecular organization remains unclear. We show here that the cleft of excitatory synapses exhibits a distinct density profile as measured by cryoelectron tomography (cryo-ET). Aiming for molecular insights, we analyzed the synapse-organizing proteins Synaptic Cell Adhesion Molecule 1 (SynCAM 1) and EphB2. Cryo-ET of SynCAM 1 knockout and overexpressor synapses showed that this immunoglobulin protein shapes the cleft's edge. SynCAM 1 delineates the postsynaptic perimeter as determined by immunoelectron microscopy and super-resolution imaging. In contrast, the EphB2 receptor tyrosine kinase is enriched deeper within the postsynaptic area. Unexpectedly, SynCAM 1 can form ensembles proximal to postsynaptic densities, and synapses containing these ensembles were larger. Postsynaptic SynCAM 1 surface puncta were not static but became enlarged after a long-term depression paradigm. These results support that the synaptic cleft is organized on a nanoscale into sub-compartments marked by distinct trans-synaptic complexes.

Methylation Levels of CADM1, MAL, and MIR124-2 in Cervical Scrapes for Triage of HIV-Infected, High-Risk HPV-Positive Women in Kenya

OBJECTIVES

To evaluate the value of cervical cell methylation markers in screening HIV-infected women also positive for high-risk human papillomavirus (hrHPV).

DESIGN

Cross-sectional and prospective.

METHODS

Two hundred forty-eight HIV-infected hrHPV-positive women enrolled in a cervical cancer screening study in Nairobi, Kenya, had colposcopy-directed biopsy and histological diagnoses. Exfoliated cervical cells were used to measure methylation levels of the CADM1, MAL, and MIR124-2 genes using quantitative methylation-specific polymerase chain reaction. Methylation levels were summarized as cycle threshold (Ct) ratios compared with the β-actin gene. Median Ct ratios were compared across histological diagnoses, with 95% confidence intervals calculated by bootstrapping. Methylation levels at 6 months were assessed in 128 women who remained hrHPV positive.

RESULTS

All 3 methylation markers showed significantly (P < 0.001) raised median Ct ratios in women with cervical intraepithelial neoplasia (CIN) grade 3 compared with women with a normal cervix. When markers were combined into a single test, the area under the receiver operating characteristic curve for prediction of CIN2 or worse (CIN2+) was 0.80. When the test was calibrated to have similar specificity, sensitivity of the combined tri-marker test for CIN2+ was comparable with cytology [atypical squamous cells of undetermined significance or worse] (89% and 95%, respectively) and superior to visual inspection with acetic acid (85% vs 70%) and HPV16/18 genotyping (65% vs 40%). Among women with no CIN2+ at baseline and persistent hrHPV at 6-month follow-up, MAL-m1 and MIR124-2 Ct ratios increased significantly.

CONCLUSIONS

Methylation markers in combination with HPV testing may offer a full molecular screening strategy to the many HIV-infected women who are also hrHPV positive.

MicroRNA-126 regulates migration and invasion of gastric cancer by targeting CADM1

OBJECTIVE

The aberrant expression of microRNAs has been demonstrated to play a crucial role in the initiation and progression of gastric cancer (GC). We here aimed to investigate the mechanism of microRNAs in the regulation of GC pathogenesis.

METHODS

Transwell chambers (8-μM pore size; Costar) were used in the in vitro migration and in vision assay. Dual luciferase reporter gene construct and dual luciferase reporter assay to identify the target of miR-126. CADM1 expression was evaluated by immunohistochemical staining. The clinical manifestations, treatments and survival were collected for statistical analysis.

RESULTS

Inhibition of miR-126 effectively reduced migration and invasion of gastric cancer cell lines. Bioinformatics and luciferase reporter assay revealed that miR-126 specifically targeted the 3'UTR of cell adhesion molecule 1 (CADM1) and regulated its expression. Down-regulation of CADM1 enhanced migration and invasion of GC cell lines. Furthermore, in tumor tissues obtained from gastric cancer patients, the expression of miR-126 was negatively correlated with CADM1 and the high expression of miR-126 combined with low expression of CADM1 might serve as a risk factor for stage1 gastric cancer patients.

CONCLUSIONS

Our study showed that miR-126, by down-regulation CADM1, enhances migration and invasion in GC cells.

[Significance of TSLC1 gene methylation and TSLC1 protein expression in the progression of cervical lesions]

OBJECTIVE

To study the expression and significance of tumor suppressor in lung cancer 1 (TSLC1) gene methylation, the expression of TSLC1 protein in cervix cancer and precancerous lesions as well as their relationship with HR-HPV DNA infection.

METHODS

The clinicopathological data of 92 cases of different cervical lesions during March 2011 to August 2012 treated in our hospital were collected. There were pathologically confirmed 10 cases of normal cervix, 26 cases of cervical intraepithelial neoplasia (CIN) I, 20 cases of CIN II, 15 cases of CIN III, and 21 cases of cervical cancer. Methylation-specific polymerase chain reaction (MSP) was used to detect the TSLC1 gene methylation status in cervical lesions, immunohistochemistry (SP) was used to detect the expressions of TSLC1 protein in cervical lesions, and the second generation hybrid capture (HC2) method was used to detect the high-risk HPV in cervical lesions.

RESULTS

The expression rate of TSLC1 gene methylation in normal cervical tissue, CIN I, CIN II, CIN III and SCC were 10.0%, 30.8%, 55.0%, 60.0%, 66.7%, respectively, showing a statistically significant difference (P = 0.004). The positive expression rate of TSLC1 protein in normal cervical tissue, CIN I, CIN II, CIN III and SCC were 100.0%, 80.8%, 65.0%, 33.3%, and 23.8%, respectively, with a significant difference (P = 0.004). In the progression from CIN to invasive cervical cancer, there was no significant correlation between TSLC1 gene methylation and HR-HPV DNA infection (P = 0.919), TSLC1 protein expression and HR-HPV DNA infection (P = 0.664). The correlation analysis showed a negative correlation between TSLC1 gene methylation and TSLC1 protein expression (r = -0.674, P < 0.001).

CONCLUSIONS

TSLC1 gene promoter methylation may be an early event in the cervical carcinogenesis, become an early sensitive marker, and serve the early prevention and prognostic prediction for cervical cancer.

Dynamic regulation of a cell adhesion protein complex including CADM1 by combinatorial analysis of FRAP with exponential curve-fitting

Protein components of cell adhesion machinery show continuous renewal even in the static state of epithelial cells and participate in the formation and maintenance of normal epithelial architecture and tumor suppression. CADM1 is a tumor suppressor belonging to the immunoglobulin superfamily of cell adhesion molecule and forms a cell adhesion complex with an actin-binding protein, 4.1B, and a scaffold protein, MPP3, in the cytoplasm. Here, we investigate dynamic regulation of the CADM1-4.1B-MPP3 complex in mature cell adhesion by fluorescence recovery after photobleaching (FRAP) analysis. Traditional FRAP analysis were performed for relatively short period of around 10 min. Here, thanks to recent advances in the sensitive laser detector systems, we examine FRAP of CADM1 complex for longer period of 60 min and analyze the recovery with exponential curve-fitting to distinguish the fractions with different diffusion constants. This approach reveals that the fluorescence recovery of CADM1 is fitted to a single exponential function with a time constant (τ) of approximately 16 min, whereas 4.1B and MPP3 are fitted to a double exponential function with two τs of approximately 40-60 sec and 16 min. The longer τ is similar to that of CADM1, suggesting that 4.1B and MPP3 have two distinct fractions, one forming a complex with CADM1 and the other present as a free pool. Fluorescence loss in photobleaching analysis supports the presence of a free pool of these proteins near the plasma membrane. Furthermore, double exponential fitting makes it possible to estimate the ratio of 4.1B and MPP3 present as a free pool and as a complex with CADM1 as approximately 3:2 and 3:1, respectively. Our analyses reveal a central role of CADM1 in stabilizing the complex with 4.1B and MPP3 and provide insight in the dynamics of adhesion complex formation.

Neuron membrane trafficking and protein kinases involved in autism and ADHD

A brain-enriched multi-domain scaffolding protein, neurobeachin has been identified as a candidate gene for autism patients. Mutations in the synaptic adhesion protein cell adhesion molecule 1 (CADM1) are also associated with autism spectrum disorder, a neurodevelopmental disorder of uncertain molecular origin. Potential roles of neurobeachin and CADM1 have been suggested to a function of vesicle transport in endosomal trafficking. It seems that protein kinase B (AKT) and cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) have key roles in the neuron membrane trafficking involved in the pathogenesis of autism. Attention deficit hyperactivity disorder (ADHD) is documented to dopaminergic insufficiencies, which is attributed to synaptic dysfunction of dopamine transporter (DAT). AKT is also essential for the DAT cell-surface redistribution. In the present paper, we summarize and discuss the importance of several protein kinases that regulate the membrane trafficking involved in autism and ADHD, suggesting new targets for therapeutic intervention.

Increased ectodomain shedding of cell adhesion molecule 1 from pancreatic islets in type 2 diabetic pancreata: correlation with hemoglobin A1c levels

Pulmonary emphysema and type 2 diabetes mellitus (T2DM), both caused by lifestyle factors, frequently concur. Respectively, the diseases affect lung alveolar and pancreatic islet cells, which express cell adhesion molecule 1 (CADM1), an immunoglobulin superfamily member. Protease-mediated ectodomain shedding of full-length CADM1 produces C-terminal fragments (CTFs) with proapoptotic activity. In emphysematous lungs, the CADM1 shedding rate and thus the level of CTFs in alveolar cells increase. In this study, CADM1 expression in islet cells was examined by western blotting. Protein was extracted from formalin-fixed, paraffin-embedded sections of pancreata isolated from patients with T2DM (n = 12) or from patients without pancreatic disease (n = 8) at autopsy. After adjusting for the number of islet cells present in the adjacent section, we found that full-length CADM1 decreased in T2DM islets, while ectodomain shedding increased. Hemoglobin A1c levels, measured when patients were alive, correlated inversely with full-length CADM1 levels (P = 0.041) and positively with ectodomain shedding rates (P = 0.001). In immunofluorescence images of T2DM islet cells, CADM1 was detected in the cytoplasm, but not on the cell membrane. Consistently, when MIN6-m9 mouse beta cells were treated with phorbol ester and trypsin to induce shedding, CADM1 immunostaining was diffuse in the cytoplasm. When a form of CTFs was exogenously expressed in MIN6-m9 cells, it localized diffusely in the cytoplasm and increased the number of apoptotic cells. These results suggest that increased CADM1 ectodomain shedding contributes to blood glucose dysregulation in T2DM by decreasing full-length CADM1 and producing CTFs that accumulate in the cytoplasm and promote apoptosis of beta cells. Thus, this study has identified a molecular alteration shared by pulmonary emphysema and T2DM.

Combined CADM1/MAL methylation and cytology testing for colposcopy triage of high-risk HPV-positive women

Primary screening for high-risk human papillomavirus (hrHPV) requires a triage protocol. Repeat cytology testing at baseline and after 6 to 12 months has emerged as a reasonable triage approach, but carries the risk of loss to follow-up. Repeat cytology testing may be omitted if cytology is supplemented with another, complementary triage test at baseline. In this study, the performance of combined triage by cytology and DNA methylation analysis was assessed. In hrHPV-positive cervical scrapes (n = 250), cytology [threshold: atypical squamous cells of undetermined significance (ASCUS)], bi-marker CADM1/MAL methylation testing (at different assay thresholds), and combinations of both were evaluated for endpoints cervical intraepithelial neoplasia grade 2 or worse (CIN2(+)) and grade 3 or worse (CIN3(+)). At a predefined methylation threshold of 70% specificity for CIN3(+), combined triage revealed a CIN3(+) sensitivity of 86.8% [95% confidence interval (CI), 76.1-97.6] compared with 65.8% (95% CI, 50.7-80.9) for sole cytology triage testing. Corresponding CIN3(+) specificity was 64.8% (95% CI, 58.1-71.5) for combined triage and 78.6% (95% CI, 72.8-84.3) for sole cytology triage testing. For CIN2(+), the sensitivity of combined triage testing was 84.5% (95% CI, 75.2-93.8) compared with 65.5% (95% CI, 53.3-77.7) for sole cytology triage, with corresponding specificities of 69.9% (95% CI, 63.1-76.6) and 83.5% (95% CI, 78.0-89.0), respectively. In conclusion, combined triage reached substantially higher CIN2(+)/3(+) sensitivities compared with sole cytology at a slight drop in specificity. Therefore, it is an attractive triage strategy for colposcopy of hrHPV-positive women with a high reassurance for cervical cancer and advanced CIN lesions.

LncRNA TSLC1-AS1 is a novel tumor suppressor in glioma

Growing evidence demonstrates that long non coding RNAs (lncRNAs) play an important role in cancer origination and progression. A novel lncRNA, TSLC1-AS1, is the antisense transcript of tumor suppressor TSLC1. The expression profile and function of TSLC1-AS1 in glioma were investigated using Real-Time Quantitative PCR and siRNA knockdown. The data showed that TSLC1-AS1 expression was down-regulated in tumor tissues compared with that in adjacent normal tissues, and negatively associated with the WHO criteria of the tumors. Overexpression of TSLC1-AS1 resulted in up-regulation of TSLC1 and significant inhibition of cell proliferation, migration and invasion in U87 cells, while knockdown of TSLC1-AS1 in SNB-19 cells showed the opposite effect. The expression of TSLC1-AS1 was also positively correlated with other tumor suppressors NF1, VHL, PIK3R1 and negatively correlated with the oncogene BRAF. The results suggested that TSLC1-AS1 was a tumor suppressor of glioma and a mediator of TSLC1 expression. LncRNA TSLC1-AS1 may serve as a potential biomarker and therapeutic target for glioma.

Decreased expression of a novel lncRNA CADM1-AS1 is associated with poor prognosis in patients with clear cell renal cell carcinomas

The clear cell renal cell carcinoma (ccRCC) is the most common subtype in renal cell carcinomas. Rapidly accumulating studies show that the long non-coding RNAs (lncRNAs) may play essential roles in cancers. In this study, we investigated the expression pattern of a novel lncRNA CADM1-AS1 in ccRCC by quantitative real time PCR. The results showed that CADM1-AS1 expression was down-regulated in tumor tissues in 64 patients with ccRCC compared with adjacent non-tumor tissues. Furthermore, the expression of CADM1-AS1 was positively correlated with the expression of mRNA CADM1 in ccRCC specimens (R = 0.611, P <0.0001). Decreased CADM1-AS1 expression was correlated with the progression of AJCC stage (P = 0.039) and worse survival of ccRCC patients (P <0.05). Also, multivariate analysis identified low CADM1-AS1 expression as an independent prognostic factor for ccRCC (P <0.001, HR = 0.211, 95% CI = 0.088-0.504). In addition, we used small interfering RNA (siRNA) to evaluate the biological function of CADM1-AS1 in vitro. The results showed that CADM1-AS1 expression was positively associated with CADM1 mRNA expression in 786-O cells and ACHN cells. Functional experiments demonstrated markedly enhanced ability of growth and migration, and reduced apoptotic rate in CADM1-AS1 knocking down in 786-O cells. Conversely, overexpression of CADM1-AS1 showed a significant decrease in growth and migration, along with an increase in apoptotic rate in ACHN cells. In conclusion, our data demonstrated CADM1-AS1 is a new tumor suppressor in ccRCC which regulates cell proliferation, apoptosis and migration via the expression pattern of "CADM1-AS1/CADM1 mRNA gene pairs". CADM1-AS1 may be a potential biomarker and therapeutic target in patients with ccRCC.

Trans-homophilic interaction of CADM1 activates PI3K by forming a complex with MAGuK-family proteins MPP3 and Dlg

CADM1 (Cell adhesion molecule 1), a cell adhesion molecule belonging to the immunoglobulin superfamily, is involved in cell-cell interaction and the formation and maintenance of epithelial structure. Expression of CADM1 is frequently down-regulated in various tumors derived from epithelial cells. However, the intracellular signaling pathways activated by CADM1-mediated cell adhesion remain unknown. Here, we established a cell-based spreading assay to analyze the signaling pathway specifically activated by the trans-homophilic interaction of CADM1. In the assay, MDCK cells expressing exogenous CADM1 were incubated on the glass coated with a recombinant extracellular fragment of CADM1, and the degree of cell spreading was quantified by measuring their surface area. Assay screening of 104 chemical inhibitors with known functions revealed that LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), efficiently suppressed cell spreading in a dose-dependent manner. Inhibitors of Akt and Rac1, downstream effectors of PI3K, also partially suppressed cell spreading, while the addition of both inhibitors blocked cell spreading to the same extent as did LY294002. Furthermore, MPP3 and Dlg, membrane-associated guanylate kinase homologs (MAGuK) proteins, connect CADM1 with p85 of PI3K by forming a multi-protein complex at the periphery of cells. These results suggest that trans-homophilic interaction mediated by CADM1 activates the PI3K pathway to reorganize the actin cytoskeleton and form epithelial cell structure.

CADM1 controls actin cytoskeleton assembly and regulates extracellular matrix adhesion in human mast cells

CADM1 is a major receptor for the adhesion of mast cells (MCs) to fibroblasts, human airway smooth muscle cells (HASMCs) and neurons. It also regulates E-cadherin and alpha6beta4 integrin in other cell types. Here we investigated a role for CADM1 in MC adhesion to both cells and extracellular matrix (ECM). Downregulation of CADM1 in the human MC line HMC-1 resulted not only in reduced adhesion to HASMCs, but also reduced adhesion to their ECM. Time-course studies in the presence of EDTA to inhibit integrins demonstrated that CADM1 provided fast initial adhesion to HASMCs and assisted with slower adhesion to ECM. CADM1 downregulation, but not antibody-dependent CADM1 inhibition, reduced MC adhesion to ECM, suggesting indirect regulation of ECM adhesion. To investigate potential mechanisms, phosphotyrosine signalling and polymerisation of actin filaments, essential for integrin-mediated adhesion, were examined. Modulation of CADM1 expression positively correlated with surface KIT levels and polymerisation of cortical F-actin in HMC-1 cells. It also influenced phosphotyrosine signalling and KIT tyrosine autophosphorylation. CADM1 accounted for 46% of surface KIT levels and 31% of F-actin in HMC-1 cells. CADM1 downregulation resulted in elongation of cortical actin filaments in both HMC-1 cells and human lung MCs and increased cell rigidity of HMC-1 cells. Collectively these data suggest that CADM1 is a key adhesion receptor, which regulates MC net adhesion, both directly through CADM1-dependent adhesion, and indirectly through the regulation of other adhesion receptors. The latter is likely to occur via docking of KIT and polymerisation of cortical F-actin. Here we propose a stepwise model of adhesion with CADM1 as a driving force for net MC adhesion.

Detection of methylation of the promoter region of the MAL and CADM1 genes by pyrosequencing in cervical carcinoma

OBJECTIVE

Cervical cancer is the second most common cancer disease affecting the female population. A key factor in development of the disease is the human papillomavirus infection (HPV). The disease is also impacted by epigenetic changes such as DNA methylation, which causes activation or exclusion of certain genes, and simultaneously the hypermethylation of cytosines in the promoters and turn-off of previously active genes occur. In this study, we focused on the introduction of pyrosequencing for the detection of DNA methylation of the selected CADM1 and MAL genes.

METHODS

DNA was isolated from cytological cervical smear of patients with different types of dysplasia [L-SIL (n=14), ASC-US (n=15), H-SIL (n=1)] and four control samples from healthy women. Prepared samples were further analyzed by bisulfite conversion and subsequent pyrosequencing (Pyromark Q96 ID, Qiagen, Germany). We examined the extent of methylation of CpG islands and as control samples of this method we used a fully methylated and unmethylated DNA. Methylation level (Met level) from each sample was quantified as the mean value [sum of all methylated CpG islands in %/total number of CpG islands (MAL n=4; CADM1 n=3)].

RESULTS

In total, 30 clinical samples and 4 control samples from healthy women were analyzed. By means of the analysis of the CADM1promoter region, the values of the Met level were obtained [fully methylated DNA (94.83 and 88); completely unmethylated DNA (0 and 0); and control samples from healthy patients (6.825 and 0.825), L-SIL (2.107 and 2.778), ASC-US (7.313 and 3.626), H-SIL (0 and 0)]. By means of the analysis of the MAL promoter region, the values of Met level were obtained [fully methylated DNA (53.25); completely unmethylated DNA (0.875); and control samples from healthy patients (2.925), L-SIL (1.517), ASC-US (2.833), and H-SIL (4)].

CONCLUSION

We introduced a pyrosequencing method for quantification of methylation of CADM1, MAL promoter regions, and detected methylations in clinical samples and also some basal methylation in healthy women.

Tumor suppressor in lung cancer 1 (TSLC1), a novel tumor suppressor gene, is implicated in the regulation of proliferation, invasion, cell cycle, apoptosis, and tumorigenicity in cutaneous squamous cell carcinoma

Tumor suppressor in lung cancer 1 (TSLC1) is tightly implicated in a variety of biological processes and plays critical roles in tumor development and progression. However, the roles of TSLC1 in cutaneous squamous cell carcinoma (CSCC) remain to be unraveled. Here, we reported the TSLC1 gene that was significantly downregulated in CSCC tissues and cells, and survival times of patients with TSLC1 at a low level were markedly lower than that at a high level (P = 0.0070). A stepwise investigation demonstrated that an elevated TSLC1 level evoked obvious proliferation and invasion inhibitions and arrested cell cycle at G0/G1 phase in A431 cells. Moreover, increase of caspase-3 activity mediated by elevated TSLC1 level induced cell apoptosis in A431 cells. Most notably, upregulation of TSLC1 expression reduced the numbers of colony formation and tumorigenicity. Collectively, our results presented herein suggest that TSLC1 as tumor suppressor may play prominent roles in development and progression of CSCC via regulation of different biological processes.

Necl-4/SynCAM-4 is expressed in myelinating oligodendrocytes but not required for axonal myelination

The timing and progression of axonal myelination are precisely controlled by intercellular interactions between neurons and glia in development. Previous in vitro studies demonstrated that Nectin like 4 (Necl-4, also known as cell adhesion molecule Cadm-4 or SynCAM-4) plays an essential role in axonal myelination by Schwann cells in the peripheral nervous system (PNS). However, the role of Necl-4 protein in axonal myelination in the developing central nervous system (CNS) has remained unknown. In this study, we discovered upregulation of Necl-4 expression in mature oligodendrocytes at perinatal stages when axons undergo active myelination. We generated Necl4 gene knockout mice, but found that disruption of Necl-4 gene did not affect oligodendrocyte differentiation and myelin formation in the CNS. Surprisingly, disruption of Necl-4 had no significant effect on axonal myelination in the PNS either. Therefore, our results demonstrated that Necl-4 is dispensable for axonal myelination in the developing nervous system.

CADM1 is a key receptor mediating human mast cell adhesion to human lung fibroblasts and airway smooth muscle cells

Background

Mast cells (MCs) play a central role in the development of many diseases including asthma and pulmonary fibrosis. Interactions of human lung mast cells (HLMCs) with human airway smooth muscle cells (HASMCs) are partially dependent on adhesion mediated by cell adhesion molecule-1 (CADM1), but the adhesion mechanism through which HLMCs interact with human lung fibroblasts (HLFs) is not known. CADM1 is expressed as several isoforms (SP4, SP1, SP6) in HLMCs, with SP4 dominant. These isoforms differentially regulate HLMC homotypic adhesion and survival.

Objective

In this study we have investigated the role of CADM1 isoforms in the adhesion of HLMCs and HMC-1 cells to primary HASMCs and HLFs.

Methods

CADM1 overexpression or downregulation was achieved using adenoviral delivery of CADM1 short hairpin RNAs or isoform-specific cDNAs respectively.

Results

Downregulation of CADM1 attenuated both HLMC and HMC-1 adhesion to both primary HASMCs and HLFs. Overexpression of either SP1 or SP4 isoforms did not alter MC adhesion to HASMCs, whereas overexpression of SP4, but not SP1, significantly increased both HMC-1 cell and HLMC adhesion to HLFs. The expression level of CADM1 SP4 strongly predicted the extent of MC adhesion; linear regression indicated that CADM1 accounts for up to 67% and 32% of adhesion to HLFs for HMC-1 cells and HLMCs, respectively. HLFs supported HLMC proliferation and survival through a CADM1-dependent mechanism. With respect to CADM1 counter-receptor expression, HLFs expressed both CADM1 and nectin-3, whereas HASMCs expressed only nectin-3.

Conclusion and Clinical Relevance

Collectively these data indicate that the CADM1 SP4 isoform is a key receptor mediating human MC adhesion to HASMCs and HLFs. The differential expression of CADM1 counter-receptors on HLFs compared to HASMCs may allow the specific targeting of either HLMC-HLF or HLMC-HASMC interactions in the lung parenchyma and airways.

The synaptic adhesion molecule SynCAM 1 contributes to cocaine effects on synapse structure and psychostimulant behavior

Drugs of abuse have acute and persistent effects on synapse structure and addiction-related behaviors. Trans-synaptic interactions can control synapse development, and synaptic cell adhesion molecule (SynCAM) proteins (also named nectin-like molecules) are immunoglobulin adhesion proteins that span the synaptic cleft and induce excitatory synapses. Our studies now reveal that the loss of SynCAM 1 in knockout (KO) mice reduces excitatory synapse number in nucleus accumbens (NAc). SynCAM 1 additionally contributes to the structural remodeling of NAc synapses in response to the psychostimulant cocaine. Specifically, we find that cocaine administration increases the density of stubby spines on medium spiny neurons in NAc, and that maintaining this increase requires SynCAM 1. Furthermore, mushroom-type spines on these neurons are structurally more plastic when SynCAM 1 is absent, and challenging drug-withdrawn mice with cocaine shortens these spines in SynCAM 1 KO mice. These effects are correlated with changes on the behavioral level, where SynCAM 1 contributes to the psychostimulant effects of cocaine as measured after acute and repeated administration, and in drug-withdrawn mice. Together, our results provide evidence that the loss of a synapse-organizing adhesion molecule can modulate cocaine effects on spine structures in NAc and increases vulnerability to the behavioral actions of cocaine. SynCAM-dependent pathways may therefore represent novel points of therapeutic intervention after exposure to drugs of abuse.

Cadm1 is a metastasis susceptibility gene that suppresses metastasis by modifying tumor interaction with the cell-mediated immunity

Metastasis is a complex process utilizing both tumor-cell-autonomous properties and host-derived factors, including cellular immunity. We have previously shown that germline polymorphisms can modify tumor cell metastatic capabilities through cell-autonomous mechanisms. However, how metastasis susceptibility genes interact with the tumor stroma is incompletely understood. Here, we employ a complex genetic screen to identify Cadm1 as a novel modifier of metastasis. We demonstrate that Cadm1 can specifically suppress metastasis without affecting primary tumor growth. Unexpectedly, Cadm1 did not alter tumor-cell-autonomous properties such as proliferation or invasion, but required the host's adaptive immune system to affect metastasis. The metastasis-suppressing effect of Cadm1 was lost in mice lacking T cell–mediated immunity, which was partially phenocopied by depleting CD8⁺ T cells in immune-competent mice. Our data show a novel function for Cadm1 in suppressing metastasis by sensitizing tumor cells to immune surveillance mechanisms, and this is the first report of a heritable metastasis susceptibility gene engaging tumor non-autonomous factors.

Metastasis, the dissemination and growth of tumor cells in organs distinct from which they originated, is the most common cause of cancer-related death. Accumulating evidence indicates that an individual's genetic background, the heritable complement of genetic variations that distinguish individuals, not only contributes to overall cancer risk, but also specifically influences metastatic potential. Using a mouse model of metastatic breast cancer and complex genetic analysis, we have identified Cadm1 as a metastasis susceptibility gene. Cadm1 was previously identified as a tumor suppressor in lung adenocarcinoma, and reductions in its expression have been associated with poor survival in numerous cancer types. In this manuscript, we use in vivo modeling to show that high expression of Cadm1 inhibits pulmonary metastasis, while knockdown of Cadm1 promotes the metastatic capability of tumor cells. We further show that the metastasis-suppressive effect of Cadm1 expression is lost in mice lacking T cell–mediated immunity and that this effect is partially mediated by CD8⁺ T-lymphocytes. Our data suggest that the inverse correlation between Cadm1 expression and disease-free survival in humans is a result of a metastasis-suppressive interaction of Cadm1 with the cell-mediated immunity.

Cell adhesion molecule 1 (CADM1) is ubiquitously present in the endothelium and smooth muscle cells of the human macro- and micro-vasculature

Cell adhesion molecule 1 (CADM1) is a member of the immunoglobulin cell adhesion molecule family. Recently, we identified CADM1 to be a novel risk factor for venous thrombosis in a large, protein C deficient, thrombophilic family and showed, for the first time, the expression of CADM1 in endothelial cells (Hasstedt et al. in Blood 114:3084-3091, 2009). To further investigate its role in venous thrombosis, as well as other vasculopathies, we undertook a systematic confocal microscopic investigation for the presence of CADM1 in the vasculature of 28 different human tissues. Paraffin embedded tissue sections were dual immunostained with an antibody against CADM1, together with an antibody against either von Willebrand factor (to identify endothelial cells), or α-smooth muscle actin (to identify smooth muscle cells). The results showed that CADM1 was ubiquitously present in endothelial cells and smooth muscle cells in the vasculature from all 28 tissues, though its representation in the various classes of vessels was tissue dependent.

Dissecting epigenetic silencing complexity in the mouse lung cancer suppressor gene Cadm1

Disease-oriented functional analysis of epigenetic factors and their regulatory mechanisms in aberrant silencing is a prerequisite for better diagnostics and therapy. Yet, the precise mechanisms are still unclear and complex, involving the interplay of several effectors including nucleosome positioning, DNA methylation, histone variants and histone modifications. We investigated the epigenetic silencing complexity in the tumor suppressor gene Cadm1 in mouse lung cancer progenitor cell lines, exhibiting promoter hypermethylation associated with transcriptional repression, but mostly unresponsive to demethylating drug treatments. After predicting nucleosome positions and transcription factor binding sites along the Cadm1 promoter, we carried out single-molecule mapping with DNA methyltransferase M.SssI, which revealed in silent promoters high nucleosome occupancy and occlusion of transcription factor binding sites. Furthermore, M.SssI maps of promoters varied within and among the different lung cancer cell lines. Chromatin analysis with micrococcal nuclease also indicated variations in nucleosome positioning to have implications in the binding of transcription factors near nucleosome borders. Chromatin immunoprecipitation showed that histone variants (H2A.Z and H3.3), and opposing histone modification marks (H3K4me3 and H3K27me3) all colocalized in the same nucleosome positions that is reminiscent of epigenetic plasticity in embryonic stem cells. Altogether, epigenetic silencing complexity in the promoter region of Cadm1 is not only defined by DNA hypermethylation, but high nucleosome occupancy, altered nucleosome positioning, and ‘bivalent’ histone modifications, also likely contributed in the transcriptional repression of this gene in the lung cancer cells. Our results will help define therapeutic intervention strategies using epigenetic drugs in lung cancer.

Astrocyte-specific disruption of SynCAM1 signaling results in ADHD-like behavioral manifestations

SynCAM1 is an adhesion molecule involved in synaptic differentiation and organization. SynCAM1 is also expressed in astroglial cells where it mediates astrocyte-to astrocyte and glial-neuronal adhesive communication. In astrocytes, SynCAM1 is functionally linked to erbB4 receptors, which are involved in the control of both neuronal/glial development and mature neuronal and glial function. Here we report that mice carrying a dominant-negative form of SynCAM1 specifically targeted to astrocytes (termed GFAP-DNSynCAM1 mice) exhibit disrupted diurnal locomotor activity with enhanced and more frequent episodes of activity than control littermates during the day (when the animals are normally sleeping) accompanied by shorter periods of rest. GFAP-DNSynCAM1 mice also display high levels of basal activity in the dark period (the rodent's awake/active time) that are attenuated by the psychostimulant D,L-amphetamine, and reduced anxiety levels in response to both avoidable and unavoidable provoking stimuli. These results indicate that disruption of SynCAM1-dependent astroglial function results in behavioral abnormalities similar to those described in animals model of attention-deficit hyperactive disorder (ADHD), and suggest a hitherto unappreciated contribution of glial cells to the pathophysiology of this disorder.

Cadm1-expressing synapses on Purkinje cell dendrites are involved in mouse ultrasonic vocalization activity

Foxp2(R552H) knock-in (KI) mouse pups with a mutation related to human speech-language disorders exhibit poor development of cerebellar Purkinje cells and impaired ultrasonic vocalization (USV), a communication tool for mother-offspring interactions. Thus, human speech and mouse USV appear to have a Foxp2-mediated common molecular basis in the cerebellum. Mutations in the gene encoding the synaptic adhesion molecule CADM1 (RA175/Necl2/SynCAM1/Cadm1) have been identified in people with autism spectrum disorder (ASD) who have impaired speech and language. In the present study, we show that both Cadm1-deficient knockout (KO) pups and Foxp2(R552H) KI pups exhibit impaired USV and smaller cerebellums. Cadm1 was preferentially localized to the apical-distal portion of the dendritic arbor of Purkinje cells in the molecular layer of wild-type pups, and VGluT1 level decreased in the cerebellum of Cadm1 KO mice. In addition, we detected reduced immunoreactivity of Cadm1 and VGluT1 on the poorly developed dendritic arbor of Purkinje cells in the Foxp2(R552H) KI pups. However, Cadm1 mRNA expression was not altered in the Foxp2(R552H) KI pups. These results suggest that although the Foxp2 transcription factor does not target Cadm1, Cadm1 at the synapses of Purkinje cells and parallel fibers is necessary for USV function. The loss of Cadm1-expressing synapses on the dendrites of Purkinje cells may be associated with the USV impairment that Cadm1 KO and Foxp2(R552H) KI mice exhibit.

Adhesion molecule CADM1 contributes to gap junctional communication among pancreatic islet α-cells and prevents their excessive secretion of glucagon

Cell adhesion molecule-1 (CADM1) is a recently identified adhesion molecule of pancreatic islet α-cells that mediates nerve-α-cell interactions via trans-homophilic binding and serves anatomical units for the autonomic control of glucagon secretion. CADM1 also mediates attachment between adjacent α-cells. Since gap junctional intercellular communication (GJIC) among islet cells is essential for islet hormone secretion, we examined whether CADM1 promotes GJIC among α-cells and subsequently participates in glucagon secretion regulation. Dye transfer assays using αTC6 mouse α-cells, which endogenously express CADM1, supported this possibility; efficient cell-to-cell spread of gap junction-permeable dye was detected in clusters of αTC6 cells transfected with nonspecific, but not with CADM1-targeting, siRNA. Immunocytochemical analysis of connexin 36, a major component of the gap junction among αTC6 cells, revealed that it was localized exclusively to the cell membrane in CADM1-non-targeted αTC6 cells, but diffusely to the cytoplasm in CADM1-targeted cells. Next, we incubated CADM1-targeted and non-targeted αTC6 cells in a medium containing 1 mM glucose and 200 mM arginine for 30 min to induce glucagon secretion, and found that the targeted cells secreted three times more glucagon than did the non-targeted. We conducted similar experiments using pancreatic islets that were freshly isolated from wild-type and CADM1-knockout mice, and expressed glucagon secretion as ratios relative to baseline values. The increase in ratio was larger in CADM1-knockout islets than in wild-type islets. These results suggest that CADM1 may serve as a volume limiter of glucagon secretion by sustaining α-cell attachment necessary for efficient GJIC.

Alterations of ATM and CADM1 in chromosomal 11q22.3-23.2 region are associated with the development of invasive cervical carcinoma

To understand the importance of chr11q22.3-23.2 region in the development of cervical cancer, we have studied the genetic and epigenetic alterations of the candidate genes ATM, PPP2R1B, SDHD and CADM1 in cervical intraepithelial neoplasia (CIN) and cervical carcinoma (CACX) samples. Our study revealed low expression and high alterations (methylation/deletion) (55-59%) of ATM and CADM1 genes along with poor patient outcome. The alterations of ATM and CADM1 are associated with the progression of tumor from CIN to Stage I/II, thus implying their role in early invasiveness. The two genes, PPP2R1B and SDHD, lying in between ATM and CADM1, have low frequency of alterations, and majority of the alterations are in CACX samples, indicating that their alterations might be associated with disease progression. Expressions (mRNA/protein) of the genes showed concordance with their molecular alterations. Significant co-alteration of ATM and CADM1 points to their synergic action for the development of CACX. Mutation is, however, a rare phenomenon for inactivation of ATM. Association between the alteration of ATM and CHEK1 and poor survival of the patients having co-alterations of ATM and CHEK1 points to the DNA damage response pathway disruption in development of CACX. Thus, our data suggest that inactivation of ATM-CHEK1-associated DNA damage response pathway and CADM1-associated signaling network might have an important role in the development of CACX.

The synaptic cell adhesion molecule, SynCAM1, mediates astrocyte-to-astrocyte and astrocyte-to-GnRH neuron adhesiveness in the mouse hypothalamus

We previously identified synaptic cell adhesion molecule 1 (SynCAM1) as a component of a genetic network involved in the hypothalamic control of female puberty. Although it is well established that SynCAM1 is a synaptic adhesion molecule, its contribution to hypothalamic function is unknown. Here we show that, in addition to the expected neuronal localization illustrated by its presence in GnRH neurons, SynCAM1 is expressed in hypothalamic astrocytes. Cell adhesion assays indicated that SynCAM is recognized by both GnRH neurons and astrocytes as an adhesive partner and promotes cell-cell adhesiveness via homophilic, extracellular domain-mediated interactions. Alternative splicing of the SynCAM1 primary mRNA transcript yields four mRNAs encoding membrane-spanning SynCAM1 isoforms. Variants 1 and 4 are predicted to be both N and O glycosylated. Hypothalamic astrocytes and GnRH-producing GT1-7 cells express mainly isoform 4 mRNA, and sequential N- and O-deglycosylation of proteins extracted from these cells yields progressively smaller SynCAM1 species, indicating that isoform 4 is the predominant SynCAM1 variant expressed in astrocytes and GT1-7 cells. Neither cell type expresses the products of two other SynCAM genes (SynCAM2 and SynCAM3), suggesting that SynCAM-mediated astrocyte-astrocyte and astrocyte-GnRH neuron adhesiveness is mostly mediated by SynCAM1 homophilic interactions. When erbB4 receptor function is disrupted in astrocytes, via transgenic expression of a dominant-negative erbB4 receptor form, SynCAM1-mediated adhesiveness is severely compromised. Conversely, SynCAM1 adhesive behavior is rapidly, but transiently, enhanced in astrocytes by ligand-dependent activation of erbB4 receptors, suggesting that erbB4-mediated events affecting SynCAM1 function contribute to regulate astrocyte adhesive communication.

Changes in gene expression in human meibomian gland dysfunction

PURPOSE

Meibomian gland dysfunction (MGD) may be the leading cause of dry eye syndrome throughout the world. However, the precise mechanism(s) underlying the pathogenesis of this disease is unclear. This study was conducted to identify meibomian gland genes that may promote the development and/or progression of human MGD.

METHODS

Lid tissues were obtained from male and female MGD patients and age-matched controls after eyelid surgeries (e.g., to correct entropion or ectropion). Meibomian glands were isolated and processed for RNA extraction and the analysis of gene expression.

RESULTS

The results show that MGD is associated with significant alterations in the expression of almost 400 genes in the human meibomian gland. The levels of 197 transcripts, including those encoding various small proline-rich proteins and S100 calcium-binding proteins, are significantly increased, whereas the expression of 194 genes, such as claudin 3 and cell adhesion molecule 1, is significantly decreased. These changes, which cannot be accounted for by sex differences, are accompanied by alterations in many gene ontologies (e.g., keratinization, cell cycle, and DNA repair). The findings also show that the human meibomian gland contains several highly expressed genes that are distinct from those in an adjacent tissue (i.e., conjunctival epithelium).

CONCLUSIONS

The results demonstrate that MGD is accompanied by multiple changes in gene expression in the meibomian gland. The nature of these alterations, including the upregulation of genes encoding small proline-rich proteins and S100 calcium-binding proteins, suggest that keratinization plays an important role in the pathogenesis of MGD.

Impairment of social and emotional behaviors in Cadm1-knockout mice

Cell adhesion molecule 1 (CADM1), a member of the immunoglobulin superfamily, mediates synaptic cell adhesion. Missense mutations in the CADM1 gene have been identified in autism spectrum disorder (ASD) patients. In the present study, we examined emotional behaviors, social behaviors and motor performances in Cadm1-knockout (KO) mice. Cadm1-KO mice showed increased anxiety-related behavior in open-field and light-dark transition tests. Social behaviors of Cadm1-KO mice were impaired in social interaction, resident-intruder and social memory/recognition tests. Furthermore, motor coordination and gait of Cadm1-KO mice were impaired in rotarod and footprint tests. Our study demonstrates that CADM1 plays roles in regulating emotional behaviors, social behaviors and motor performances, and that CADM1 has important implications for psychiatric disorders with disruptions in social behavior, such as autism.

Aberrant DNA methylation occurs in colon neoplasms arising in the azoxymethane colon cancer model

Mouse models of intestinal tumors have advanced our understanding of the role of gene mutations in colorectal malignancy. However, the utility of these systems for studying the role of epigenetic alterations in intestinal neoplasms remains to be defined. Consequently, we assessed the role of aberrant DNA methylation in the azoxymethane (AOM) rodent model of colon cancer. AOM induced tumors display global DNA hypomethylation, which is similar to human colorectal cancer. We next assessed the methylation status of a panel of candidate genes previously shown to be aberrantly methylated in human cancer or in mouse models of malignant neoplasms. This analysis revealed different patterns of DNA methylation that were gene specific. Zik1 and Gja9 demonstrated cancer-specific aberrant DNA methylation, whereas, Cdkn2a/p16, Igfbp3, Mgmt, Id4, and Cxcr4 were methylated in both the AOM tumors and normal colon mucosa. No aberrant methylation of Dapk1 or Mlt1 was detected in the neoplasms, but normal colon mucosa samples displayed methylation of these genes. Finally, p19(Arf), Tslc1, Hltf, and Mlh1 were unmethylated in both the AOM tumors and normal colon mucosa. Thus, aberrant DNA methylation does occur in AOM tumors, although the frequency of aberrantly methylated genes appears to be less common than in human colorectal cancer. Additional studies are necessary to further characterize the patterns of aberrantly methylated genes in AOM tumors.

Dispensable role of protein 4.1B/DAL-1 in rodent adrenal medulla regarding generation of pheochromocytoma and plasmalemmal localization of TSLC1

Protein 4.1B is a membrane skeletal protein expressed in various organs, and is associated with tumor suppressor in lung cancer-1 (TSLC1) in vitro. Although involvement of 4.1B in the intercellular junctions and tumor-suppression was suggested, some controversial results posed questions to the general tumor-suppressive function of 4.1B and its relation to TSLC1 in vivo. In this study, the expression of 4.1B and its interaction with TSLC1 were examined in rodent adrenal gland, and the involvement of 4.1B in tumorigenesis and the effect of 4.1B deficiency on TSLC1 distribution were also investigated using rodent pheochromocytoma and 4.1B-knockout mice. Although plasmalemmal immunolocalization of 4.1B was shown in chromaffin cells of rodent adrenal medulla, expression of 4.1B was maintained in developed pheochromocytoma, and morphological abnormality or pheochromocytoma generation could not be found in 4.1B-deficient mice. Furthermore, molecular interaction and colocalization of 4.1B and TSLC1 were observed in mouse adrenal gland, but the immunolocalization of TSLC1 along chromaffin cell membranes was not affected in the 4.1B-deficient mice. These results suggest that the function of 4.1B as tumor suppressor might significantly differ among organs and species, and that plasmalemmal retention of TSLC1 would be maintained by molecules other than 4.1B interacting in rodent chromaffin cells.