Measurement of anti-suprabasin antibodies, multiple cytokines and chemokines as potential predictive biomarkers for neuropsychiatric systemic lupus erythematosus.

Neuropsychiatric systemic lupus erythematosus (NPSLE) varies in presentation and is one of the leading causes of morbidity and mortality among patients with SLE. This study determined the most critical serum biomarkers for the development of NPSLE as they may have clinical utility prior to the onset of neuropsychiatric symptoms. We retrospectively analyzed 35 NPSLE patients, 34 SLE patients, 20 viral meningitis (VM) patients, and 16 relapsing-remitting multiple sclerosis (MS) patients. We measured anti-suprabasin antibodies concentrations in serum by using Luciferase immunoprecipitation system (LIPS) assay. The serum concentrations of cytokines/chemokines were measured by using multiplex bead-based assay. We found serum FGF-2 level was significantly higher in the NPSLE group compared to the SLE group and the healthy control group. The anti-suprabasin antibody relative concentration (SRC) has high positive predictive values for the development of NPSLE. The most essential biomarkers are VEGF, anti-suprabasin antibodies, sCD40L, IL-10, GRO, MDC, IL-8, IL-9, TNF-α, MIP-1α.

Suprabasin: Role in human cancers and other diseases.

Suprabasin (SBSN), a gene with unknown function located in q13 region of chromosome 19, was first found to be expressed in the basal layer of the stratified epithelium in mouse and human tissues and was thought to be a potential precursor of keratinized capsules. However, in recent years, significant progress has been made in the study of SBSN in a variety of human diseases. One common theme appears to be the effect of SBSN on tumor progression, such as invasion, metastasis and resistance. However, the function and mechanism of action of SBSN is still elusive. In this study, we reviewed the literature on SBSN in the PubMed database to identify the basic characteristics, biological functions, and roles of SBSN in cancer and other diseases. In particular, we focused on the potential mechanisms of SBSN activity, to improve our understanding of the complex function of this protein and provide a theoretical basis for further research on the role of SBSN in cancer and other diseases.

Gel-Based Proteomic Identification of Suprabasin as a Potential New Candidate Biomarker in Endometrial Cancer.

Endometrial cancer (EC) is the most frequent gynaecologic cancer in postmenopausal women. We used 2D-DIGE and mass spectrometry to identify candidate biomarkers in endometrial cancer, analysing the serum protein contents of 10 patients versus 10 control subjects. Using gel-based proteomics, we identified 24 candidate biomarkers, considering only spots with a fold change in volume percentage ≥ 1.5 or intensity change ≤ 0.6, which were significantly different between cases and controls (p < 0.05). We used Western blotting analysis both in the serum and tissue of 43 patients for data validation. Among the identified proteins, we selected Suprabasin (SBSN), an oncogene previously associated with poor prognosis in different cancers. SBSN principal isoforms were subjected to Western blotting analysis in serum and surgery-excised tissue: both isoforms were downregulated in the tissue. However, in serum, isoform 1 was upregulated, while isoform 2 was downregulated. Data-mining on the TCGA and GTEx projects, using the GEPIA2.0 interface, indicated a diminished SBSN expression in the Uterine Corpus Endometrial Cancer (UCEC) database compared to normal tissue, confirming proteomic results. These results suggest that SBSN, specifically isoform 2, in tissue or serum, could be a potential novel biomarker in endometrial cancer.

Novel anti-suprabasin antibodies may contribute to the pathogenesis of neuropsychiatric systemic lupus erythematosus.

Neuropsychiatric systemic lupus erythematosus (NPSLE) is often difficult to diagnose and distinguish from other diseases, because no NPSLE-specific antibodies have been identified. We developed a novel proteomic strategy for identifying and profiling antigens in immune complexes in the cerebrospinal fluid (CSF), and applied this strategy to 26 NPSLE patients. As controls, we also included 25 SLE patients without neuropsychiatric manifestations (SLE), 15 with relapsing remitting multiple sclerosis (MS) and 10 with normal pressure hydrocephalus (NPH). We identified immune complexes of suprabasin (SBSN) in the CSF of the NPSLE group. The titer of anti-SBSN antibodies was significantly higher in the CSF of the NPSLE group compared to those of the SLE, MS and NPH groups. Microarray data showed that the senescence and autophagy pathways were significantly changed in astrocytes exposed to anti-SBSN antibodies. Our findings indicate that SBSN could be a novel autoantibody for the evaluation of suspected NPSLE.

Suprabasin as a novel tumor endothelial cell marker.

Recent studies have reported that stromal cells contribute to tumor progression. We previously demonstrated that tumor endothelial cells (TEC) characteristics were different from those of normal endothelial cells (NEC). Furthermore, we performed gene profile analysis in TEC and NEC, revealing that suprabasin (SBSN) was upregulated in TEC compared with NEC. However, its role in TEC is still unknown. Here we showed that SBSN expression was higher in isolated human and mouse TEC than in NEC. SBSN knockdown inhibited the migration and tube formation ability of TEC. We also showed that the AKT pathway was a downstream factor of SBSN. These findings suggest that SBSN is involved in the angiogenic potential of TEC and may be a novel TEC marker.

Insights into Intrinsic Atopic Dermatitis: immunogenicity, Dysbiosis, and Imaging (Reflectance Confocal Microscopy, Optical Coherence Tomography).

Atopic dermatitis (AD) is a frequent inflammatory condition that usually begins during early childhood, but it increasingly starts to debut, even in the elderly. Based on immunoglobulin E (IgE) levels and clinical features, two subsets of this disease have been recognized: intrinsic and extrinsic. When speaking about AD, most specialists think about filaggrin (FLG) mutations resulting in epidermal barrier defects, which is the case in most atopic patients, but some have a normal barrier, as seen by imaging, and still have specific clinical lesions along with metal allergies. Specific molecules (IL-10, IFN-γ, and HBD-3) have been shown to greatly impact the interactions between internal and external factors in this peculiar form of AD. A less-known protein, suprabasin, has been highlighted as a promising explanation for nickel anomalies in intrinsic AD.

Suprabasin enhances the invasion, migration, and angiogenic ability of oral squamous cell carcinoma cells under hypoxic conditions.

Suprabasin (SBSN) is a secreted protein that is isolated as a novel gene expressed in differentiated keratinocytes in mice and humans. It induces various cellular processes such as proliferation, invasion, metastasis, migration, angiogenesis, apoptosis, therapy and immune resistance. The role of SBSN was investigated in oral squamous cell carcinoma (OSCC) under hypoxic conditions using the SAS, HSC­3, and HSC­4 cell lines. Hypoxia induced SBSN mRNA and protein expression in OSCC cells and normal human epidermal keratinocytes (NHEKs), and this was most prominent in SAS cells. The function of SBSN in SAS cells was analyzed using 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide (MTT); 5­bromo­2'­deoxyuridine (BrdU); cell cycle, caspase 3/7, invasion, migration, and tube formation assays; and gelatin zymography. Overexpression of SBSN decreased MTT activity, but the results of BrdU and cell cycle assays indicated upregulation of cell proliferation. Western blot analysis for cyclin­related proteins indicated involvement of cyclin pathways. However, SBSN did not strongly suppress apoptosis and autophagy, as revealed by caspase 3/7 assay and western blotting for p62 and LC3. Additionally, SBSN increased cell invasion more under hypoxia than under normoxia, and this resulted from increased cell migration, not from matrix metalloprotease activity or epithelial­mesenchymal transition. Furthermore, SBSN induced angiogenesis more strongly under hypoxia than under normoxia. Analysis using reverse transcription­quantitative PCR showed that vascular endothelial growth factor (VEGF) mRNA was not altered by the knockdown or overexpression of SBSN VEGF, suggesting that VEGF is not located downstream of SBSN. These results demonstrated the importance of SBSN in the maintenance of survival and proliferation, invasion and angiogenesis of OSCC cells under hypoxia.

Role of suprabasin, a new biomarker in squamous cell carcinoma and basal cell carcinoma.

INTRODUCTION: Suprabasin is a newly discovered protein linked to various human diseases including cancer. It may does have an effect on the development and expression of some non-melanoma skin cancers such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). BCC is the most common non-melanoma skin cancers worldwide, while SCC comes as the second in terms of prevalence. In certain cases, it is very important to distinguish between these two carcinomas from each other and from normal skin samples. This study was aimed at investigating the characteristics of suprabasin expression in squamous cell carcinoma and basal cell carcinoma and whether it can be used as a biomarker. MATERIALS AND METHODS: Thirty control, ninety SCC and thirty BCC cases obtained from the archives of the Department of Pathology, Faculty of Medicine, Firat University, were examined by immunohistochemical staining for suprabasin. RESULTS: Increased suprabasin expression was observed in tumour tissues and normal skin samples in SCC. As the grade increased in SCC, suprabasin expression decreased. No suprabasin expression was observed in the lesion area in BCC. CONCLUSION: Suprabasin can be reported as a biomarker for SCC and used to differentiate SCC from BCC. Expression of suprabasin in SCC can be used to determine grade. Absence of suprabasin expression in BCC can be used for differential diagnosis.

New candidates in the differential diagnosis of malignant mesothelioma from benign mesothelial hyperplasia and adenocarcinoma; DARS2 and suprabasin.

OBJECTIVES: Malignant mesothelioma (MM) is a primary malignant tumour with a very bad prognosis, which develops from the mesothelial cells lining the serosal surfaces. Because MM can show a wide variety of histological patterns and its cytomorphological features are quite extensive, it is often confused with lung adenocarcinomas (LAC) and reactive mesothelial hyperplasia (RMH). The immunohistochemical examination method is the most useful method for discrimination. In this study, we aimed to determine the value of suprabasin and DARS2 markers in the differential diagnosis of RMH, MM and LAC. METHODS: Thirty MM, 30 LAC and 30 RMH samples selected from the archive of Firat University Hospital Pathology Department Laboratory were included in this study. Suprabasin and DARS2 markers were applied to the samples immunohistochemically and their place in the differential diagnosis was examined. RESULTS: Although DARS2 expression was observed in RMH, MM and adenocarcinoma samples, Suprabasin expression was only observed in adenocarcinoma. There was a significant difference between the groups in terms of DARS2 and Suprabasin expression. No suprabasin expression was detected in MM and RMH. CONCLUSION: Suprabasin and DARS2 may be proposed as new biomarkers to differentiate MM from LAC.

Role of Suprabasin in the Dedifferentiation of Follicular Epithelial Cell-Derived Thyroid Cancer and Identification of Related Immune Markers.

Background: Aberrant regulation of suprabasin (SBSN) is associated with the development of cancer and immune disorders. SBSN influences tumor cell migration, proliferation, angiogenesis, and immune resistance. In this study, we investigated the potential correlation between SBSN expression and immune infiltration in thyroid cancer. Methods: The expression of SBSN in 80 papillary thyroid carcinoma (PTC) specimens was determined using quantitative reverse-transcription polymerase chain reaction, western blotting, and immunohistochemical staining. The expression of SBSN in 9 cases of poorly differentiated thyroid carcinoma (PDTC) and 18 cases of anaplastic thyroid carcinoma (ATC) was evaluated by immunohistochemical staining. Comprehensive bioinformatics analysis of SBSN expression was performed using The Cancer Genome Atlas and Gene Expression Omnibus datasets, and the relationship of SBSN expression with M2 macrophages and T regulatory cells (Tregs) in ATC and PTC was verified by immunohistochemical staining. Results: Compared with those in adjacent normal tissues, the expression levels of SBSN mRNA and protein were significantly higher in PTC tissues. SBSN expression level was correlated with that of cervical lymph node metastasis in PTC patients. Immunohistochemical staining results showed statistically significant differences among high-positive expression rates of SBSN in PTC, PDTC, and ATC. Functional enrichment analysis showed that SBSN expression was associated with pathways related to cancer, cell signaling, and immune response. Furthermore, analysis of the tumor microenvironment (using CIBERSORT-ABS and xCell algorithms) showed that SBSN expression affected immune cell infiltration and the cancer immunity cycle, and immunohistochemistry confirmed a significant increase in M2 macrophage and Treg infiltration in tumor tissues with high-positive SBSN expression. Conclusion: These findings reveal that SBSN may be involved in thyroid carcinogenesis, tumor dedifferentiation progression, and immunosuppression as an important regulator of tumor immune cell infiltration.

Suprabasin-A Review.

Among the ~22,000 human genes, very few remain that have unknown functions. One such example is suprabasin (SBSN). Originally described as a component of the cornified envelope, the function of stratified epithelia-expressed SBSN is unknown. Both the lack of knowledge about the gene role under physiological conditions and the emerging link of SBSN to various human diseases, including cancer, attract research interest. The association of SBSN expression with poor prognosis of patients suffering from oesophageal carcinoma, glioblastoma multiforme, and myelodysplastic syndromes suggests that SBSN may play a role in human tumourigenesis. Three SBSN isoforms code for the secreted proteins with putative function as signalling molecules, yet with poorly described effects. In this first review about SBSN, we summarised the current knowledge accumulated since its original description, and we discuss the potential mechanisms and roles of SBSN in both physiology and pathology.

Aberrantly elevated suprabasin in the bone marrow as a candidate biomarker of advanced disease state in myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are preleukemic disorders characterized by clonal growth of mutant hematopoietic stem and progenitor cells. MDS are associated with proinflammatory signaling, dysregulated immune response, and cell death in the bone marrow (BM). Aging, autoinflammation and autoimmunity are crucial features of disease progression, concordant with promoting growth of malignant clones and accumulation of mutations. Suprabasin (SBSN), a recently proposed proto-oncogene of unknown function, physiologically expressed in stratified epithelia, is associated with poor prognosis of several human malignancies. Here, we showed that SBSN is expressed in the BM by myeloid cell subpopulations, including myeloid-derived suppressor cells, and is secreted into BM plasma and peripheral blood of MDS patients. The highest expression of SBSN was present in a patient group with poor prognosis. SBSN levels in the BM correlated positively with blast percentage and negatively with CCL2 chemokine levels and lymphocyte count. In vitro treatment of leukemic cells with interferon-gamma and demethylating agent 5-azacytidine (5-AC) induced SBSN expression. This indicated that aberrant cytokine levels in the BM and epigenetic landscape modifications in MDS patients may underlie ectopic expression of SBSN. Our findings suggest SBSN as a candidate biomarker of high-risk MDS with a possible role in disease progression and therapy resistance.

Decreased expression of suprabasin induces aberrant differentiation and apoptosis of epidermal keratinocytes: Possible role for atopic dermatitis.

BACKGROUND: Suprabasin (SBSN), a secreted protein, is expressed in various epithelial tissues. The role of SBSN in epidermal differentiation and atopic dermatitis (AD) pathology remains largely unknown. OBJECTIVE: To evaluate the effects of SBSN on epidermal keratinocytes and its role in AD. METHODS: We examined the SBSN expression levels in the stratum corneum and the epidermis by proteome analysis and immunohistochemistry, respectively. The serum SBSN concentration was measured by ELISA. These values were compared between AD and healthy control. Morphological changes in the epidermis were investigated in SBSN-knockdown three-dimensional human living skin equivalent (LSE) model with or without IL-4/IL-13. RESULTS: Epidermal SBSN expression was decreased in AD lesional skin compared to healthy skin, as assessed by the stratum corneum proteome analysis and immunohistochemistry. The SBSN serum levels were significantly lower in AD patients than in normal subjects (P<0.05). The SBSN-deficient LSE exhibited compact stratum corneum, immature stratum granulosum, and increased keratinocyte apoptosis. Th2 cytokines, IL-4 and IL-13, did not affect SBSN expression in LSE. There were no differentiation-associated makers that were affected by the SBSN knockdown. SBSN deficiency-induced apoptosis of keratinocytes was exaggerated by IL-4/IL-13, and accordingly, the addition of recombinant SBSN induced significant keratinocyte proliferation (P<0.05). CONCLUSION: Our data demonstrated that SBSN regulates normal epidermal barrier. Th2 cytokines unaffect SBSN expression in keratinocytes, but promote SBSN deficiency-induced apoptosis. It is suggested that SBSN has an anti-apoptotic activity, and its deficiency is involved in the pathogenesis of AD.

Interferon-regulated suprabasin is essential for stress-induced stem-like cell conversion and therapy resistance of human malignancies.

Radiation and chemotherapy represent standard-of-care cancer treatments. However, most patients eventually experience tumour recurrence, treatment failure and metastatic dissemination with fatal consequences. To elucidate the molecular mechanisms of resistance to radio- and chemotherapy, we exposed human cancer cell lines (HeLa, MCF-7 and DU145) to clinically relevant doses of 5-azacytidine or ionizing radiation and compared the transcript profiles of all surviving cell subpopulations, including low-adherent stem-like cells. Stress-mobilized low-adherent cell fractions differed from other survivors in terms of deregulation of hundreds of genes, including those involved in interferon response. Exposure of cancer cells to interferon-gamma but not interferon-beta resulted in the development of a heterogeneous, low-adherent fraction comprising not only apoptotic/necrotic cells but also live cells exhibiting active Notch signalling and expressing stem-cell markers. Chemical inhibition of mitogen-activated protein kinase/ERK kinase (MEK) or siRNA-mediated knockdown of extracellular signal-regulated kinase 1/2 (Erk1/2) and interferon responsible factor 1 (IRF1) prevented mobilization of the surviving low-adherent population, indicating that interferon-gamma-mediated loss of adhesion and anoikis resistance required an active Erk pathway interlinked with interferon signalling by transcription factor IRF1. Notably, a skin-specific protein suprabasin (SBSN), a recently identified oncoprotein, was among the top scoring genes upregulated in surviving low-adherent cancer cells induced by 5-azacytidine or irradiation. SBSN expression required the activity of the MEK/Erk pathway, and siRNA-mediated knockdown of SBSN suppressed the low-adherent fraction in irradiated, interferon-gamma- and 5-azacytidine-treated cells, respectively, implicating SBSN in genotoxic stress-induced phenotypic plasticity and stress resistance. Importantly, SBSN expression was observed in human clinical specimens of colon and ovarian carcinomas, as well as in circulating tumour cells and metastases of the 4T1 mouse model. The association of SBSN expression with progressive stages of cancer development indicates its role in cancer evolution and therapy resistance.