Expression of CD138 (Syndecan-1) in renal cell carcinoma is reduced with increasing nuclear grade

Syndecan-1 Promotes Hepatocyte-Like Differentiation of Hepatoma Cells Targeting Ets-1 and AP-1

Syndecan-1 is a transmembrane heparan sulfate proteoglycan which is indispensable in the structural and functional integrity of epithelia. Normal hepatocytes display strong cell surface expression of syndecan-1; however, upon malignant transformation, they may lose it from their cell surfaces. In this study, we demonstrate that re-expression of full-length or ectodomain-deleted syndecan-1 in hepatocellular carcinoma cells downregulates phosphorylation of ERK1/2 and p38, with the truncated form exerting an even stronger effect than the full-length protein. Furthermore, overexpression of syndecan-1 in hepatoma cells is associated with a shift of heparan sulfate structure toward a highly sulfated type specific for normal liver. As a result, cell proliferation and proteolytic shedding of syndecan-1 from the cell surface are restrained, which facilitates redifferentiation of hepatoma cells to a more hepatocyte-like phenotype. Our results highlight the importance of syndecan-1 in the formation and maintenance of differentiated epithelial characteristics in hepatocytes partly via the HGF/ERK/Ets-1 signal transduction pathway. Downregulation of Ets-1 expression alone, however, was not sufficient to replicate the phenotype of syndecan-1 overexpressing cells, indicating the need for additional molecular mechanisms. Accordingly, a reporter gene assay revealed the inhibition of Ets-1 as well as AP-1 transcription factor-induced promoter activation, presumably an effect of the heparan sulfate switch.

Involvement of Syndecan-1 and Heparanase in Cancer and Inflammation

The cell surface heparan sulfate proteoglycan Syndecan-1 acts as an important co-receptor for receptor tyrosine kinases and chemokine receptors, and as an adhesion receptor for structural glycoproteins of the extracellular matrix. It serves as a substrate for heparanase, an endo-β-glucuronidase that degrades specific domains of heparan sulfate carbohydrate chains and thereby alters the functional status of the proteoglycan and of Syndecan-1-bound ligands. Syndecan-1 and heparanase show multiple levels of functional interactions, resulting in mutual regulation of their expression, processing, and activity. These interactions are of particular relevance in the context of inflammation and malignant disease. Studies in animal models have revealed a mechanistic role of Syndecan-1 and heparanase in the regulation of contact allergies, kidney inflammation, multiple sclerosis, inflammatory bowel disease, and inflammation-associated tumorigenesis. Moreover, functional interactions between Syndecan-1 and heparanase modulate virtually all steps of tumor progression as defined in the Hallmarks of Cancer. Due to their prognostic value in cancer, and their mechanistic involvement in tumor progression, Syndecan-1 and heparanase have emerged as important drug targets. Data in preclinical models and preclinical phase I/II studies have already yielded promising results that provide a translational perspective.

Serum and tissue syndecan-1 levels in renal cell carcinoma

Background

The proteoglycan syndecan-1 is involved in cell proliferation, adhesion and angiogenesis. It was shown to be involved in cancer progression in different tumor entities. So far, the role of syndecan-1 in renal cell carcinoma (RCC), one of the most common diseases in urologic oncology, was little described. Purpose of the present study was to obtain serum concentrations and tissue expression levels of syndecan-1 in a cohort of patients diagnosed with RCC.

Methods

Clinical and follow-up data were obtained from 413 RCC patients. SDC1 levels were determined in serum samples of 100 patients by enzyme-linked immunosorbent assay and tissue SDC1 expression was measured by immunohistochemistry (IHC) in 343 cases. Results were correlated with clinicopathological and follow-up data.

Results

Five and ten years overall and cancer specific survival were 67% and 56% [overall survival (OS)] and 79% and 76% [cancer-specific survival (CSS)]. In female patients and locally advanced disease (≥T3), tissue SDC1 expression was decreased (female 85.6% vs. male 71.1% low tissue SDC1 expression, P=0.0153 and ≤T2 70.0% vs. ≥T3 87.2% low tissue SDC1 expression, P=0.0055) compared to male patients and organ confined disease. Locally advanced tumor stage, presence of lymph node or distant metastases, high Fuhrman grading and clear cell carcinoma as histopathological subtype were independent prognostic factors for reduced CSS and OS. There was no impact of serum SDC1 (sSDC1) serum concentration or SDC1 tissue protein expression on OS, CSS or recurrence free survival (RFS) in uni- or multivariable analysis.

Conclusions

sSDC1 concentration or SDC1 tissue protein expression levels had no influence on patients' prognosis in the present cohort of patients diagnosed with RCC.

Prevalence of Syndecan-1 (CD138) Expression in Different Kinds of Human Tumors and Normal Tissues

Syndecan-1 (CD138) is a transmembrane proteoglycan known to be expressed in various normal and malignant tissues. It is of interest because of a possible prognostic role of differential expression in tumors and its role as a target for indatuximab, a monoclonal antibody coupled with a cytotoxic agent. To comprehensively analyze CD138 in normal and neoplastic tissues, we used tissue microarrays (TMAs) for analyzing immunohistochemically detectable CD138 expression in 2,518 tissue samples from 85 different tumor entities and 76 different normal tissue types. The data showed that CD138 expression is abundant in tumors. At least an occasional weak CD138 immunostaining could be detected in 71 of 82 (87%) different tumor types, and 58 entities (71%) had at least one tumor with a strong positivity. In normal tissues, a particularly strong expression was found in normal squamous epithelium of various organs, goblet and columnar cells of the gastrointestinal tract, and in hepatocytes. The highly standardized analysis of most human cancer types resulted in a ranking order of tumors according to the frequency and levels of CD138 expression. CD138 immunostaining was highest in squamous cell carcinomas such as from the esophagus (100%), cervix uteri (79.5%), lung (85.7%), vagina (89.7%) or vulva (73.3%), and in invasive urothelial cancer (76.2%). In adenocarcinomas, CD138 was also high in lung (82.9%) and colorectal cancer (85.3%) but often lower in pancreas (73.3%), stomach (54.2% in intestinal type), or prostate carcinomas (16.3%). CD138 expression was usually low or absent in germ cell tumors, sarcomas, endocrine tumors including thyroid cancer, and neuroendocrine tumors. In summary, the preferential expression in squamous cell carcinomas of various sites makes these cancers prime targets for anti-CD138 treatments once these might become available. Abundant expression in many different normal tissues might pose obstacles to exploiting CD138 as a therapeutic target, however.

Molecular and clinical profiles of syndecan-1 in solid and hematological cancer for prognosis and precision medicine

Syndecan-1 (SDC1, CD138) is a key cell surface adhesion molecule essential for maintaining cell morphology and interaction with the surrounding microenvironment. Deregulation of SDC1 contributes to cancer progression by promoting cell proliferation, metastasis, invasion and angiogenesis, and is associated with relapse through chemoresistance. SDC1 expression level is also associated with responses to chemotherapy and with prognosis in multiple solid and hematological cancers, including multiple myeloma and Hodgkin lymphoma. At the tissue level, the expression levels of SDC1 and the released extracellular domain of SDC1 correlate with tumor malignancy, phenotype, and metastatic potential for both solid and hematological tumors in a tissue-specific manner. The SDC1 expression profile varies among cancer types, but the differential expression signatures between normal and cancer cells in epithelial and stromal compartments are directly associated with aggressiveness of tumors and patient's clinical outcome and survival. Therefore, relevant biomarkers of SDC signaling may be useful for selecting patients that would most likely respond to a particular therapy at the time of diagnosis or perhaps for predicting relapse. In addition, the reciprocal expression signature of SDC between tumor epithelial and stromal compartments may have synergistic value for patient selection and the prediction of clinical outcome.

The role of syndecan-1 in cellular signaling and its effects on heparan sulfate biosynthesis in mesenchymal tumors

Proteoglycans (PGs) and in particular the syndecans are involved in the differentiation process across the epithelial-mesenchymal axis, principally through their ability to bind growth factors and modulate their downstream signaling. Malignant tumors have individual proteoglycan profiles, which are closely associated with their differentiation and biological behavior, mesenchymal tumors showing a different profile from that of epithelial tumors. Syndecan-1 is the main syndecan of epithelial malignancies, whereas in sarcomas its expression level is generally low, in accordance with their mesenchymal phenotype and highly malignant behavior. This proteoglycan is often overexpressed in adenocarcinoma cells, whereas mesothelioma and fibrosarcoma cells express syndecan-2 and syndecan-4 more abundantly. Increased expression of syndecan-1 in mesenchymal tumors changes the tumor cell morphology to an epithelioid direction whereas downregulation results in a change in shape from polygonal to spindle-like morphology. Although syndecan-1 plays major roles on the cell-surface, there are also intracellular functions, which are not very well studied. On the functional level, syndecan-1 affects mesenchymal tumor cell proliferation, adhesion, migration and motility, and the effect varies with the different domains of the core protein. Syndecan-1 may exert stimulatory or inhibitory effects, depending on the concentration of various mitogens, enzymes, and signaling molecules, the ratio between the shed and membrane-associated syndecan-1 and histological grade of the tumour. Growth factor signaling seems to be delicately controlled by regulatory loops involving the syndecan expression levels and their sulfation patterns. Overexpression of syndecan-1 modulates the biosynthesis and sulfation of heparan sulfate and it also affects the expression of other PGs. On transcriptomic level, syndecan-1 modulation results in profound effects on genes involved in regulation of cell growth.

Syndecan-1 overexpression is associated with nonluminal subtypes and poor prognosis in advanced breast cancer

OBJECTIVES

Syndecan-1 expression is decreased in diverse tumor types but remains controversial in breast carcinomas. The goal of the study was to examine syndecan-1 expression in breast carcinoma and its prognostic significance.

METHODS

The epithelial expression of syndecan-1 was examined in tissue microarrays constructed from 62 consecutive breast carcinoma cases diagnosed between 1997 and 2004 with distant organ metastasis and 10 consecutive control cases (breast carcinoma with no distant metastasis after at least 8 years of follow-up). The prognostic significance of syndecan-1 was estimated by utilizing a Cox proportional hazards regression model.

RESULTS

Among tumors with distant metastasis, syndecan-1 expression was significantly associated with a higher histologic grade and inversely related to hormonal receptor status. The HER2 subtype and triple-negative carcinomas exhibited markedly higher syndecan-1 levels than those of luminal subtypes, while the latter remained significantly higher than nonmetastatic control cases. Furthermore, high syndecan-1 expression had a negative impact on both overall and disease-free survival rates.

CONCLUSIONS

These findings suggest that syndecan-1 may regulate breast cancer cell behavior and thus deserves further investigation to ascertain its potential as a therapeutic target, especially in metastatic, triple-negative carcinomas.

Syndecan-1 expression in human glioma is correlated with advanced tumor progression and poor prognosis

Syndecan-1 has been implicated in tumorigenesis and progression of various human malignancies. Recent studies have demonstrated that syndecan-1 may have a different function and biological activity depending on the specific tumor type. Therefore, the aim of this study was to investigate the clinical significance of syndecan-1 in human gliomas. One hundred and sixteen glioma patients (26 World Health Organization (WHO) grade I, 30 WHO grade II, 30 WHO grade III, and 30 WHO grade IV) and 15 normal brain specimens acquired from 15 patients undergoing surgery for epilepsy as control were collected. Immunohistochemistry assay, quantitative real-time PCR and Western blot analysis were carried out to detect the expression of syndecan-1 at gene and protein levels in glioma samples with different WHO grades. Syndecan-1 gene and protein levels were both higher in glioma tissues compared to controls (both P < 0.001). In addition, its expression levels increased with ascending tumor WHO grades according to the results of immunohistochemistry assay, quantitative real-time PCR and Western blot analysis. Moreover, the survival rate of syndecan-1-positive patients was significantly lower than that of syndecan-1-negative patients (P = 0.006). We further confirmed that the increased expression of syndecan-1 was an independent prognostic indicator in glioma by multivariate analysis (P = 0.01). Our data suggest for the first time that the increased expression of syndecan-1 at gene and protein levels is correlated with advanced tumor progression and poor outcome in patients with glioma. Syndecan-1 might serve as a potential prognosis predictor of this dismal tumor.

CD138 (syndecan-1) expression in bone-forming tumors

CD138 (syndecan-1), a cell surface proteoglycan, is sensitive and specific for plasmacytic differentiation in hematologic disorders. Expression of CD138 has been observed in a majority of epithelial neoplasms and, rarely, soft tissue tumors. However, its expression in bone tumors has not been evaluated. We studied CD138 expression in 27 osteosarcomas, 12 benign bone-forming tumors (osteoid osteoma and osteoblastoma), and 17 reactive bone cases. CD138 expression was also evaluated in a tissue microarray (TMA) constructed from 24 osteosarcomas, 24 chondrosarcomas, 12 giant cell tumors of bone, and 9 normal bone samples. Membranous expression of CD138 was found in an average of 31% of osteosarcoma cases (16/51; 14/27 [52%] in in-house cases; 2/24 [8%] in TMA cases) and in 83% of osteoid osteoma/osteoblastoma cases (10/12). Subsequent immunoglobulin κ and λ stains were negative in the CD138+ cases. All cases of chondrosarcoma, giant cell tumor of bone, and normal/reactive bone tested were nonreactive with anti-CD138. Our results show that CD138 reactivity for neoplastic cells in bone is not a definitive marker for plasmacytic origin, and caution is required to interpret CD138+ cells from a bony lesion for which a hematologic etiology has not been established.

Expression of syndecan-1 and cathepsins D and K in advanced esophageal squamous cell carcinoma

The key features of malignant neoplasms are their local invasiveness and metastatic potential. Syndecan-1 - integral membrane heparan sulfate proteoglycan and cathepsins D and K - lysosomal proteases are important factors influencing different aspects of these processes. The study was undertaken to determine their expression in esophageal squamous cell carcinoma, and analyze relationship to selected clinicopathological features as well as to survival. Formalin-fixed, paraffin-embedded sections from 39 advanced esophageal squamous cell carcinoma were used for immunohistochemical staining. The epithelial and stromal staining were evaluated separately and compared to conventional clinicopathological features and one-year survival. Positive epithelial immunostaining for syndecan-1, cathepsin D and K were observed in 82.05%, 56.41% and 30.77% of tumors, respectively. However, stromal staining was noted in 51.28%, 51.28% and 46.15% ones, respectively. Epithelial syndecan-1-positive cases were significantly more frequent in well- and moderately differentiated carcinomas. Stromal cathepsin D expression predominated in tumors with infiltrative growth pattern. However, there were no statistically significant differences between any marker-positive and -negative groups with respect to other clinicopathological features studied. The only factors significantly influencing one-year survival were epithelial cathepsin D staining and distant metastasis. In a group of patients who survived one year post surgery, the percentage of cases with negative epithelial cathepsin D staining and without features of distant metastasis were higher. The results may suggest a relationship between syndecan-1 and cathepsins D and K with growth and invasiveness of esophageal squamous cell carcinoma, but such thesis requires further study on a larger and more heterogeneous population.

Sdc1 negatively modulates carcinoma cell motility and invasion

During cancer progression, tumor cells eventually invade the surrounding collagen-rich extracellular matrix. Here we show that squamous cell carcinoma cells strongly adhere to Type I collagen substrates but display limited motility and invasion on collagen barriers. Further analysis revealed that in addition to the alpha2beta1 integrin, a second collagen receptor was identified as Syndecan-1 (Sdc1), a cell surface heparan sulfate proteoglycan. We demonstrate that siRNA-mediated depletion of Sdc1 reduced adhesion efficiency to collagen I, whereas knockdown of Sdc4 was without effect. Importantly, silencing Sdc1 expression caused reduced focal adhesion plaque formation and enhanced cell spreading and motility on collagen I substrates, but did not alter cell motility on other ECM substrates. Sdc1 depletion ablated adhesion-induced RhoA activation. In contrast, Rac1 was strongly activated following Sdc1 knockdown, suggesting that Sdc1 may mediate the link between integrin-induced actin remodeling and motility. Taken together, these data substantiate the existence of a co-adhesion receptor system in tumor cells, whereby Sdc1 functions as a key regulator of cell motility and cell invasion by modulating RhoA and Rac activity. Downregulation of Sdc1 expression during carcinoma progression may represent a mechanism by which tumor cells become more invasive and metastatic.

Metastatic hepatocellular carcinoma with CD138 positivity: an unusual mimic of multiple myeloma?

CD138 is a monoclonal anti-syndecan-1 antibody that is often used to identify plasma cells in the bone marrow of patients with multiple myeloma (MM). Several carcinomas may also express CD138 including prostate, colon, renal cell, and hepatocellular carcinoma (HCC). We report a case of metastatic HCC that presented as a soft tissue mass on the back of a 67-year-old male. Based on the clinical and radiologic findings, MM was strongly suspected. In addition, fine-needle aspiration biopsy (FNAB) of the mass revealed neoplastic cells that were positive for CD138, both by immunohistochemistry (IHC) and flow cytometry. The cytomorphologic features however did not support a diagnosis of MM, but were consistent with metastatic HCC. Our case highlights the potential problems that may arise by over-reliance on IHC and flow cytometry. Careful morphologic assessment as well as clinical and radiologic correlation are very important when evaluating any CD138-positive neoplasm. This approach should improve diagnostic accuracy and reduce the risk of erroneous interpretation of aberrant IHC results. In addition, we examined the expression of CD138 in known cases of HCC.