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Caenorhabditis elegans syndecan (SDN-1) is required for normal egg laying and associates with the nervous system and the vulva.

In Caenorhabditis elegans, the identification of many enzymes involved in the synthesis and modification of glycosaminoglycans (GAGs), essential components of proteoglycans, has attained special attention in recent years. Mutations in all the genes that encode for GAG biosynthetic enzymes show defects in the development of the vulva, specifically in the invagination of the vulval epithelium. Mutants for certain heparan sulfate modifying enzymes present axonal and cellular guidance defects in specific neuronal classes. Although most of the enzymes involved in the biosynthesis and modification of heparan sulfate have been characterized in C. elegans, little is known regarding the core proteins to which these GAGs covalently bind in proteoglycans. A single syndecan homologue (sdn-1) has been identified in the C. elegans genome through sequence analysis. In the present study, we show that C. elegans synthesizes sulfated proteoglycans, seen as three distinct species in western blot analysis. In the sdn-1 (ok449) deletion mutant allele we observed the lack of one species, which corresponds to a 50 kDa product after heparitinase treatment. The expression of sdn-1 mRNA and sequencing revealed that sdn-1 (ok449) deletion mutants lack two glycosylation sites. Hence, the missing protein in the western blot analysis probably corresponds to SDN-1. In addition, we show that SDN-1 localizes to the C. elegans nerve ring, nerve cords and to the vulva. SDN-1 is found specifically phosphorylated in nerve ring neurons and in the vulva, in both wild-type worms and sdn-1 (ok449) deletion mutants. These mutants show a defective egg-laying phenotype. Our results show for the first time, the identification, localization and some functional aspects of syndecan in the nematode C. elegans.

Alleles↗

Utility of CD138 (syndecan-1) in distinguishing carcinomas from mesotheliomas.

CD138 (Syndecan-1) is a transmembrane heparan sulfate proteoglycan present on the surface of plasma cells and epithelial cells. CD138 is also expressed in some hematopoietic neoplasms and has recently been observed in carcinomas. We characterized CD138 expression in cell-block preparations of fluids/effusions, focusing on the distinction between carcinoma and mesothelioma. One hundred formalin-fixed, paraffin-embedded cell-block sections of fluids/effusions consisting of 58 metastatic carcinomas, 24 mesotheliomas, 11 reactive mesothelial cell proliferations, 3 lymphomas, 3 metastatic sarcomas, and 1 metastatic melanoma were stained with a monoclonal antibody against CD138. CD138 staining was observed in 32/58 (55%) metastatic carcinomas and 2/24 (8%) mesotheliomas; all reactive mesothelial cells, lymphomas, sarcomas, and melanoma were negative. CD138 is a highly specific marker in the differential diagnosis of carcinoma vs. mesothelioma. Distinct membranous staining without background staining of most inflammatory cells makes CD138 an ideal marker for cell-block preparations of fluids/effusions. It should be an integral component of the epithelial-mesothelial antibody panel.

Biomarkers, Tumor↗

Multiple myeloma cells are killed by syndecan-1-directed superantigen-activated T cells.

Multiple myeloma (MM) is an incurable plasma cell/plasmablast malignancy with a great need for innovative treatment strategies. Since experimental immunotherapy with targeted superantigens (SAg) proved to be effective in other haematopoietic tumours, we investigated whether this would also hold true for MM. We used the bacterial SAg Staphylococcus enterotoxin A (SEA), a potent activator of T cell cytotoxicity by means of its binding to particular T cell receptor Vbeta sequences on effector cells and MHC class II molecules on target cells. To eliminate potentially unspecific binding via MHC class II, SEA was point mutated (SEAm). In a second step SEAm was genetically fused to protein A (PA), resulting in a fusion protein (PA-SEAm). This fusion protein was used together with four different plasma-cell-specific/associated mAbs to direct T cells towards 10 MM target cell lines. Three of these mAbs were directed against syndecan-1/CD138, known to be highly expressed on MM and plasma cells, but absent on other haematopoietic cells. All MM cell lines proved to be sensitive to SAg-activated T cell killing (15-50% lysis), as measured in a 51Cr-release assay. This effect was clearly mediated via the plasma-cell-reactive antibodies, as control antibodies only conferred a low background lysis. MM therapy based on targeted SAgs could in theory be hampered by dysfunctional T cells in MM patients. However, we show that T cells from MM patients and healthy controls responded equally well to activation by SAg.

Antibodies, Monoclonal↗

Shift of syndecan-1 expression from epithelial to stromal cells during progression of solid tumours.

Syndecan-1 (SDC-1), a protein found on cells and in the extracellular matrix, participates in cell proliferation, cell migration and cell-matrix interactions. SDC-1 expression correlates with the maintenance of epithelial morphology and inhibition of invasiveness. In the present study, a second SDC-1 mRNA isoform was identified and the expression of both transcripts was investigated in various normal and malignant tissues. Both transcripts were coexpressed at equal levels in all tissues and organs analysed. Cancer-profiling array (CPA) analysis of 241 non-enriched tumour and normal cDNAs revealed stronger upregulation of SDC-1 in tumour tissues as compared with oligonucleotide array-based expression analysis of SDC-1 in microdissected breast, prostate, lung, and colon carcinoma cells. With in situ hybridisation and immunohistochemistry it was demonstrated that this difference in SDC-1 expression originates from stromal cells present in tumour connective tissue. But only the cells in connective tissue surrounding breast, lung, colon and bladder carcinoma showed upregulation of SDC-1. These stromal cells were characterised as spindle cells with myofibroblastic differentiation and they may contribute to the dedifferentiation of tumour cells and the development of metastasis.

Breast Neoplasms↗

Physiological degradation converts the soluble syndecan-1 ectodomain from an inhibitor to a potent activator of FGF-2.

The activity of fibroblast growth factor 2 (FGF-2) is stringently controlled. Inactive in undisturbed tissues, it is activated during injury and is critical for tissue repair. We find that this control can be imposed by the soluble syndecan-1 ectodomain, a heparan sulfate proteoglycan shed from cell surfaces into wound fluids. The ectodomain potently inhibits heparin-mediated FGF-2 mitogenicity because of the poorly sulfated domains in its heparin sulfate chains. Degradation of these regions by platelet heparanase produces heparin-like heparin sulfate fragments that markedly activate FGF-2 mitogenicity and are found in wound fluids. These results establish a novel physiological control for FGF-2 and suggest new ways to modulate FGF activity.

Binding Sites↗

Mammary gland development requires syndecan-1 to create a beta-catenin/TCF-responsive mammary epithelial subpopulation.

Mice with a null mutation in the cell surface heparan sulfate (HS) proteoglycan, syndecan-1 (Sdc1), develop almost normally, but resist mammary tumor development in response to Wnt-1. Here, we test the hypothesis that Sdc1 promotes Wnt-1-induced tumor development by interacting with the Wnt cell surface signaling complex. Thus, the response of Sdc1-/- mammary epithelial cells (mecs) to the intracellular, activated Wnt signal transducer, DeltaNbeta-catenin, was assayed both in vitro and in vivo, to test whether beta-catenin/TCF transactivation was Sdc1-independent. Surprisingly, we found that the expression of a canonical Wnt pathway reporter, TOP-FLASH, was reduced by 50% in both unstimulated Sdc1-/- mecs and in stimulated cells responding to Wnt1 or DeltaNbeta-catenin. Tumor development in response to DeltaNbeta-catenin was also significantly delayed on a Sdc1-/- background. Furthermore, the average beta-catenin/TCF transactivation per cell was normal in Sdc1-/- mec cultures, but the number of responsive cells was reduced by 50%. Sdc1-/- mecs show compensatory changes that maintain the number of HS chains, hence these experiments cannot test the coreceptor activity of HS for Wnt signaling. We propose that TCF-dependent transactivational activity is suppressed in 50% of cells in Sdc1-/- glands, and conclude that the major effect of Sdc1 does not map to the activity of the Wnt signaling complex, but to another pathway to create or stabilize the beta-catenin/TCF-responsive tumor precursor cells in mouse mammary gland.

Animals↗

Syndecan-1 expression by stromal fibroblasts promotes breast carcinoma growth in vivo and stimulates tumor angiogenesis.

The induction of the cell surface heparan sulfate proteoglycan syndecan-1 (Sdc1) in stromal fibroblasts is observed in more than 70% of human breast carcinomas. Using a coculture model, we have recently shown that stromal cell-derived Sdc1 stimulates carcinoma cell proliferation in vitro, and that this activity requires Sdc1 glycanation. In the present study, we investigated the effect of stromal cell Sdc1 on breast carcinoma growth in vivo. MDA-MB-231 human breast carcinoma cells were inoculated into the flanks of athymic nude mice either alone, or as mixed suspensions with Sdc1-transfected or mock-transfected 3T3 mouse fibroblasts. The mixed tumors showed an intimate association between carcinoma cells and stromal fibroblasts and histologically closely resembled poorly differentiated human breast carcinomas. The presence of fibroblasts led to significantly accelerated tumor growth, which was further augmented (88% increase) by forced expression of stromal Sdc1. The hyperemic macroscopic appearance of tumors containing Sdc1-positive stromal cells contrasted with pale tumors developing in the presence of mock-transfected fibroblasts, which prompted us to examine tumor microvessels. Stromal Sdc1 expression was associated with a significantly elevated microvessel density (36% increase) and a larger vessel area (153% increase). To evaluate the relevance of this finding in human breast cancer, the relationship between stromal Sdc1 and tumor vascularity was also examined in a tissue array containing 207 human breast carcinoma samples. Similar to the xenografts, stromal Sdc1 expression correlated with both vessel density (P=0.013) and total vessel area (P=0.0026). In conclusion, stromal fibroblast-derived Sdc1 stimulates breast carcinoma growth and angiogenesis in vivo.

Animals↗

A plasmocyte selective monoclonal antibody (B-B4) recognizes syndecan-1.

We developed a new monoclonal antibody. B-B4, which specifically identifies human plasma cells. It strongly reacts with all multiple myeloma cell lines and with malignant plasma cells of all tumour samples of the multiple myeloma patients tested. B-B4 does not react with any peripheral blood, bone marrow or tonsil cells. Cloning of the B-B4 antigen reveals that the monoclonal antibody recognizes syndecan-1. It appears that the monoclonal antibody B-B4 is a suitable marker for human plasmocyte identification among haemopoietic cells and a useful probe for the diagnosis of haematological malignancies. Furthermore, this monoclonal antibody can be used for depletions prior to CD34 grafting.

Antibodies, Monoclonal↗

Syndecan-1 expression is regulated in an isoform-specific manner by the farnesoid-X receptor.

Syndecan-1 (SDC1), a transmembrane heparan sulfate proteoglycan that participates in the binding and internalization of extracellular ligands, was identified in a screen designed to isolate genes that are regulated by the farnesoid X-receptor (FXR, NR1H4). Treatment of human hepatocytes with either naturally occurring (chenodeoxycholic acid) or synthetic (GW4064) FXR ligands resulted in both induction of SDC1 mRNA and enhanced binding, internalization, and degradation of low density lipoprotein. Transient transfection assays, using wild-type and mutant SDC1 promoter-luciferase genes, led to the identification of a nuclear hormone receptor-binding hexad arranged as a direct repeat separated by one nucleotide (DR-1) in the proximal promoter that was necessary and sufficient for activation by FXR. The wild-type, but not a mutated DR-1 element, conferred FXR responsiveness to a heterologous thymidine kinase promoter-reporter gene. Four murine FXR isoforms have been identified recently that differ either at their amino terminus and/or by the presence or absence of four amino acids in the hinge region. Interestingly, the activities of the human SDC1 promoter-reporter constructs were highly induced by the two FXR isoforms that do not contain the four-amino acid insert and were unresponsive to the isoforms containing the four amino acids. Thus, current studies demonstrate that hepatic SDC1 is induced in an FXR isoform-specific manner. Increased expression of SDC1 may account in part for the hypotriglyceridemic effect that can result from the administration of chenodeoxycholic acid to humans.

Base Sequence↗

Heparanase deglycanation of syndecan-1 is required for binding of the epithelial-restricted prosecretory mitogen lacritin.

Cell surface heparan sulfate (HS) proteoglycans are carbohydrate-rich regulators of cell migratory, mitogenic, secretory, and inflammatory activity that bind and present soluble heparin-binding growth factors (e.g., fibroblast growth factor, Wnt, Hh, transforming growth factor beta, amphiregulin, and hepatocyte growth factor) to their respective signaling receptors. We demonstrate that the deglycanated core protein of syndecan-1 (SDC1) and not HS chains nor SDC2 or -4, appears to target the epithelial selective prosecretory mitogen lacritin. An important and novel step in this mechanism is that binding necessitates prior partial or complete removal of HS chains by endogenous heparanase. This limits lacritin activity to sites where heparanase appears to predominate, such as sites of exocrine cell migration, secretion, renewal, and inflammation. Binding is mutually specified by lacritin's C-terminal mitogenic domain and SDC1's N terminus. Heparanase modification of the latter transforms a widely expressed HS proteoglycan into a highly selective surface-binding protein. This novel example of cell specification through extracellular modification of an HS proteoglycan has broad implications in development, homeostasis, and disease.

Cell Line↗

Increased plasma cell frequency and accumulation of abnormal syndecan-1plus T-cells in Igmu-deficient/lpr mice.

The expression of muH chain is an important checkpoint in B cell development. In mice deficient for IgM transmembrane tail exons (muMT mice) B cell development is blocked at the pro-B stage. However, we showed that Fas-deficient muMT mice (muMT/lpr) develop a very small population of isotype-switched B cells and produce high titers of self-reactive serum antibodies. In addition, muMT/lpr mice develop severe lymphoproliferation and both pathologic processes occur at young ages. This may suggest that lack of Fas-Fas ligand signaling exacerbates murine lupus in B cell lymphopenic mice. To test this we analyzed antibody and plasma cell formation, and accumulation of abnormal T cells in muMT/lpr mice. Our results show that the muMT/lpr mouse is particularly permissive for the development and accumulation of antibody-producing cells, thereby explaining the high titers of serum antibodies in these mice. In addition, we found that accumulating cells in spleen and lymph nodes of muMT/lpr mice are alphabeta T cells expressing the abnormal B220+/CD3+ surface markers, a phenotype also described for other Fas-deficient mouse models. Strikingly, we found that accumulating cells in muMT/lpr mice express the membrane proteoglycan syndecan-1, a known plasma cell marker. Development of these cells is blocked in mice deficient for TCRbeta and TCRdelta. We also found that both antibody production and lymphoproliferation in muMT/lpr mice are Th1 regulated. Our results, therefore, suggest that in the muMT/lpr mouse model a small population of isotype-switched B cells is sufficient for the initiation and propagation of Th1-regulated murine lupus.

Animals↗

Activation of an enhancer on the syndecan-1 gene is restricted to fibroblast growth factor family members in mesenchymal cells.

Fibroblast growth factors (FGFs) induce a variety of biological effects on different cell types. They activate a number of genes, including immediate-early genes, such as the transcription factors Fos and Jun, which are also common targets for other tyrosine kinase receptor-activating growth factors. Here we describe a secondary far-upstream enhancer on the syndecan-1 gene that is activated only by members of the FGF family in NIH 3T3 cells, not by other receptor tyrosine kinase-activating growth factors (e.g., epidermal growth factor, platelet-derived growth factor, insulin-like growth factor, or serum). This FGF-inducible response element (FiRE) consists of a 170-bp array of five DNA motifs which bind two FGF-inducible Fos-Jun heterodimers, one inducible AP-2-related protein, a constitutively expressed upstream stimulatory factor, and one constitutive 46-kDa transcription factor. Mutational analysis showed that both AP-1 binding motifs are required, but not sufficient, for FiRE activation. Moreover, agents such as 12-O-tetradecanoylphorbol-13-acetate, okadaic acid, or forskolin, which are known to activate AP-1 complexes and AP-1-driven promoters, fail to activate FiRE. However, FiRE can be activated by the tyrosine kinase phosphatase inhibitor orthovanadate. Taken together, this data implies a differential activation of growth factor-initiated signaling on AP-1-driven regulatory elements.

3T3 Cells↗

Induction of syndecan-1 expression in stromal fibroblasts promotes proliferation of human breast cancer cells.

Infiltrating carcinomas characteristically elicit a reactive stromal response, and accumulating evidence indicates that tumor stroma fibroblasts reciprocally promote tumor development and growth. The cell surface heparan sulfate proteoglycan, syndecan-1 (Sdc1), is thought to function as a coreceptor for growth factor and extracellular matrix interactions, and Sdc1 expression is induced in reactive stromal cells in both mice and man. Mice with a targeted mutation in Sdc1 show reduced tumor development in response to oncogene expression and altered responses to other pathological stimuli that are associated with the induction of stromal Sdc1. Here, we test the hypothesis that Sdc1 is required for the growth-promoting activities of reactive stroma. We found that when highly invasive carcinoma cells (MDA-MB-231) were placed in contact with mouse embryonic fibroblasts (MEFs) in a coculture model, Sdc1 expression was induced. Sdc1 was not induced by less invasive or normal cell lines (T47D and NMuMG). Furthermore, the growth of MDA-MB-231 cells was enhanced by 42% when cocultured with Sdc1+/+ MEFs compared with Sdc1-/- MEFs. When T47D cells were cocultured with fibroblasts that expressed transfected Sdc1, these Sdc1-positive fibroblasts stimulated growth of the breast epithelial cells by 85% compared with untransfected controls. The growth-promoting effect was completely abolished when fibroblasts were transfected with mutant Sdc1 lacking heparan sulfate attachment sites. In conclusion, we have demonstrated that a growth-promoting loop exists between breast cancer cells and their stroma that depends on the activity of glycanated Sdc1.

Animals↗

Syndecan-1 mediates internalization of apoE-VLDL through a low density lipoprotein receptor-related protein (LRP)-independent, non-clathrin-mediated pathway.

BACKGROUND: Triacylglyerol-rich very low density lipoprotein (VLDL) particles are the primary carriers of fatty acids in the circulation and as such serve as a rich energy source for peripheral tissues. Receptor-mediated uptake of these particles is dependent upon prior association with apolipoprotein E (apoE-VLDL) and is brought about by cell surface heparan sulfate proteoglycans (HSPG) in some cell types and by the low density lipoprotein receptor-related protein (LRP) in others. Although LRP's role in apoE-VLDL uptake has been well studied, the identity of the HSPG family member that mediates apoE-VLDL uptake has not been established. We investigated if syndecan-1 (Syn-1), a transmembrane cell surface HSPG, is able to mediate the internalization of apoE-VLDL and examined the relationship between Syn-1 and LRP toward apoE-VLDL uptake. For this study, we used a human fibroblast cell line (GM00701) that expresses large amounts of LRP, but possesses no LDL receptor activity to eliminate its contributions toward apoE-VLDL uptake. RESULTS: Although LRP in these cells is fully active as established by substantial alpha2macroglobulin binding and internalization, uptake of apoE-VLDL is absent. Expression of human Syn-1 cDNA restored apoE-VLDL binding and uptake by these cells. Competition for this uptake with an LRP ligand-binding antagonist had little or no effect, whereas co-incubation with heparin abolished apoE-VLDL internalization. Depleting Syn-1 expressing cells of K+, to block clathrin-mediated endocytosis, showed no inhibition of Syn-1 internalization of apoE-VLDL. By contrast, treatment of cells with nystatin to inhibit lipid raft function, prevented the uptake of apoE-VLDL by Syn-1. CONCLUSION: These data demonstrate that Syn-1 is able to mediate apoE-VLDL uptake in human fibroblasts with little or no contribution from LRP and that the endocytic path taken by Syn-1 is clathrin-independent and relies upon lipid raft function. These data are consistent with previous studies demonstrating Syn-1 association with lipid raft domains.

3T3-L1 Cells↗

Binding of syndecan-like cell surface proteoglycan receptors is required for Neisseria gonorrhoeae entry into human mucosal cells.

Bacterial invasion of human mucosal cells is considered to be a primary event in the pathogenesis of a gonococcal infection. Here we report that cell surface heparan sulfate proteoglycans may play a role in the establishment of an infection, by functioning as receptors for the invasion-promoting gonococcal opacity protein adhesin. Chemical modification and enzymatic removal of proteoglycan receptors from cultured epithelial cells abolished opacity protein-associated gonococcal invasion, and mutant cell lines defective in proteoglycan synthesis were poor substrates for gonococcal attachment. The addition of purified receptor and receptor analogues totally blocked gonococcal entry into the cells. Heparin-affinity chromatography and receptor binding assays using recombinant bacteria producing defined opacity proteins and reconstituted receptor or purified receptor fragments as probes, identified one particular member of the opacity protein family (MS11-Opa30) as the primary ligand for this novel class of receptors for bacteria. Heparan sulfate proteoglycans with gonococcal binding activity were purified from various cell types derived from target tissues of gonococcal infection, including ME-180 endocervical cells and primary cultures of human corneal epithelium. The physico-chemical properties of the receptor indicate that it may belong to the syndecan proteoglycan family.

Animals↗

Modulation of microvascular signaling by heparan sulfate matrix: studies in syndecan-4 transgenic mice.

The onset of tissue ischemia is associated with significant changes in the expression of heparan sulfate- (HS) carrying core proteins that, in turn, lead to alterations in composition of the extracellular HS matrix. Since HS can bind numerous growth factors and cytokines, such changes in the HS matrix content can have profound effects on the ability of these factors to interact with their target cells. To investigate the role of increased HS matrix content on microvascular function, we used alpha-myosin heavy chain (MHC) promoter to overexpress a HS-carrying core protein, syndecan-4, in cardiac myocytes in mice. Mice expressing the transgene (alpha MHC-S4) demonstrated a significant increase in nitric oxide (NO) release in the coronary effluent in response to fibroblast growth factor 2 (FGF2, 1 microg/mL) administration despite similar expression levels of NO synthase genes II and III (iNOS and eNOS, respectively). In vitro studies of coronary microvessels derived from alpha MHC-S4 mice demonstrated increased relaxation response to FGF2 compared to control mice. At the same time, vasodilator response to adenosine diphosphate (ADP) was significantly impaired in alpha MHC-S4 mice-derived microvessels. Addition of exogenous HS to microvessels derived from control mice enhanced FGF2-induced vasodilation while inhibiting ADP-induced vasomotion. The vasomotor activity of the endothelial receptor-independent agent (A23187) and the endothelium-independent agent (sodium nitroprusside) was not affected by heparan sulfate. These results demonstrate that alterations in HS production have a profound and heterogeneous effect on endothelial receptor-dependent vasodilators and point to a novel role of the HS matrix in regulation of microvascular homeostasis.

Adenosine Diphosphate↗

The heparan sulfate proteoglycans Dally-like and Syndecan have distinct functions in axon guidance and visual-system assembly in Drosophila.

Heparan sulfate proteoglycans (HSPGs), a class of glycosaminoglycan-modified proteins, control diverse patterning events via their regulation of growth-factor signaling and morphogen distribution. In C. elegans, zebrafish, and the mouse, heparan sulfate (HS) biosynthesis is required for normal axon guidance, and mutations affecting Syndecan (Sdc), a transmembrane HSPG, disrupt axon guidance in Drosophila embryos. Glypicans, a family of glycosylphosphatidylinositol (GPI)-linked HSPGs, are expressed on axons and growth cones in vertebrates, but their role in axon guidance has not been determined. We demonstrate here that the Drosophila glypican Dally-like protein (Dlp) is required for proper axon guidance and visual-system function. Mosaic studies revealed that Dlp is necessary in both the retina and the brain for different aspects of visual-system assembly. Sdc mutants also showed axon guidance and visual-system defects, some that overlap with dlp and others that are unique. dlp+ transgenes were able to rescue some sdc visual-system phenotypes, but sdc+ transgenes were ineffective in rescuing dlp abnormalities. Together, these findings suggest that in some contexts HS chains provide the biologically critical component, whereas in others the structure of the protein core is also essential.

Animals↗

Exploring the impact of syndecans in prostate cancer: Stage-specific roles and therapeutic implications.

Syndecans (SDCs) 1-4 are a family of transmembrane heparan sulfate proteoglycans (HSPGs) that regulate cell-cell communication, adhesion, extracellular matrix organization, and signaling pathways involved in tumor biology. In prostate cancer (PCa), accumulating evidence suggests that SDCs contribute to tumor progression, therapeutic resistance, and interactions within the tumor microenvironment. However, their specific, stage-dependent roles remain incompletely understood. This review provides an integrated synthesis of current experimental and clinical evidence on SDC1-SDC4 in PCa, complemented by exploratory analyses of publicly available transcriptomic, genomic, and proteomic datasets. In contrast, copy-number alteration (CNA) strata dichotomized by the mean for SDC1, SDC2, and SDC4 showed differences in progression-free interval. Specific CNA subclasses and relationships between CNA values and SDC mRNA or protein abundance could not be determined. Proteomic pseudotime analysis further suggested that SDC4 expression increases during PCa progression, supporting its potential involvement in advanced disease. We discuss the regulation and modulation of SDCs by androgen deprivation therapy (ADT), enzymatic shedding, integrin-mediated signaling, extracellular matrix interactions, lipid signaling pathways, and microRNA networks. In particular, SDC1-microRNA interactions may influence PCa cell proliferation, cellular senescence, epithelial-mesenchymal transition (EMT), and intracellular signaling pathways. Overall, this review highlights SDCs as context-dependent regulators of PCa biology with potential relevance as biomarkers or therapeutic targets. However, clinical translation will require independent validation, standardized assays, compartment-resolved analyses, and mechanistic confirmation.

Prognosis↗