Dermcidin Research Articles

Management of the human hair follicle microbiome by a synthetic odorant

BackgroundHuman scalp hair follicles (HFs) engage in olfactory receptor (OR)-dependent chemosensation. Activation of olfactory receptor family 2 subfamily AT member 4 (OR2AT4) by the synthetic, sandalwood-like odorant Sandalore® up-regulated HF antimicrobial peptide expression of dermcidin (DCD), which had previously been thought to be produced exclusively by sweat and sebaceous glands. ObjectivesTo understand if intrafollicular DCD production can be stimulated by a commonly used cosmetic odorant, thus altering human HF microbiome composition in a clinically beneficial manner. MethodsDCD expression was compared between fresh-frozen scalp biopsies and microdissected, full-length scalp HFs, organ-cultured in the presence/absence of the OR2AT4 agonist, Sandalore® and/or antibiotics and/or the competitive OR2AT4 antagonist, Phenirat®. Amplicon-based sequencing and microbial growth assays were performed to assess how this treatment affected the HF microbiome. ResultsSynthetic odorant treatment upregulated epithelial DCD expression and exerted antimicrobial activity in human HFs ex vivo. Combined antibiotic and odorant treatment, during an ex vivo dysbiosis event, prevented HF tissue damage and favoured a more physiological microbiome composition. Sandalore®-conditioned medium, containing higher DCD content, favoured Staphylococcus epidermidis and Malassezia restricta over S. aureus and M. globosa, while exhibiting antimicrobial activity against Cutibacterium acnes. These effects were reversed by co-administration of Phenirat®. ConclusionsWe provide the first proof-of-principle that a cosmetic odorant impacts the human HF microbiome by up-regulating antimicrobial peptide production in an olfactory receptor-dependent manner. Specifically, a synthetic sandalwood-like odorant stimulates intrafollicular DCD production, likely via OR2AT4, and thereby controls microbial overgrowth. Thus, deserving further exploration as an adjuvant therapeutic principle in the management of folliculitis and dysbiosis-associated hair diseases.

Bone Marrow Mesenchymal Stem Cell-Derived Dermcidin-Containing Migrasomes enhance LC3-Associated Phagocytosis of Pulmonary Macrophages and Protect against Post-Stroke Pneumonia.

Pneumonia is one of the leading causes of death in patients with acute ischemic stroke (AIS). Antibiotics fail to improve prognosis of patients with post-stroke pneumonia, albeit suppressing infection, due to adverse impacts on the immune system. The current study reports that bone marrow mesenchymal stem cells (BM-MSC) downregulate bacterial load in the lungs of stroke mice models. RNA-sequencing of the lung from BM-MSC-treated stroke models indicates that BM-MSC modulates pulmonary macrophage activities after cerebral ischemia. Mechanistically, BM-MSC promotes the bacterial phagocytosis of pulmonary macrophages through releasing migrasomes, which are migration-dependent extracellular vesicles. With liquid chromatography-tandem mass spectrometry (LC-MS/MS), the result shows that BM-MSC are found to load the antibacterial peptide dermcidin (DCD) in migrasomes upon bacterial stimulation. Besides the antibiotic effect, DCD enhances LC3-associated phagocytosis (LAP) of macrophages, facilitating their bacterial clearance. The data demonstrate that BM-MSC is a promising therapeutic candidate against post-stroke pneumonia, with dual functions of anti-infection and immunol modulation, which is more than a match for antibiotics treatment.

Melanoma Clinical Decision Support System: An Artificial Intelligence-Based Tool to Diagnose and Predict Disease Outcome in Early-Stage Melanoma Patients.

This study set out to assess the performance of an artificial intelligence (AI) algorithm based on clinical data and dermatoscopic imaging for the early diagnosis of melanoma, and its capacity to define the metastatic progression of melanoma through serological and histopathological biomarkers, enabling dermatologists to make more informed decisions about patient management. Integrated analysis of demographic data, images of the skin lesions, and serum and histopathological markers were analyzed in a group of 196 patients with melanoma. The interleukins (ILs) IL-4, IL-6, IL-10, and IL-17A as well as IFNγ (interferon), GM-CSF (granulocyte and macrophage colony-stimulating factor), TGFβ (transforming growth factor), and the protein DCD (dermcidin) were quantified in the serum of melanoma patients at the time of diagnosis, and the expression of the RKIP, PIRIN, BCL2, BCL3, MITF, and ANXA5 proteins was detected by immunohistochemistry (IHC) in melanoma biopsies. An AI algorithm was used to improve the early diagnosis of melanoma and to predict the risk of metastasis and of disease-free survival. Two models were obtained to predict metastasis (including "all patients" or only patients "at early stages of melanoma"), and a series of attributes were seen to predict the progression of metastasis: Breslow thickness, infiltrating BCL-2 expressing lymphocytes, and IL-4 and IL-6 serum levels. Importantly, a decrease in serum GM-CSF seems to be a marker of poor prognosis in patients with early-stage melanomas.

Application of Topical Sandalore® Increases Epidermal Dermcidin Synthesis in Organ-Cultured Human Skin ex vivo

Introduction: Several olfactory receptors (ORs) are expressed in human skin, where they regulate skin pigmentation, barrier function, wound healing, and hair growth. Previously, we found that the selective activation of OR family 2 subfamily AT member 4 (OR2AT4) by the synthetic, sandalwood-like odorant Sandalore® differentially stimulates the expression of antimicrobial peptides (AMPs) in human scalp hair follicle epithelium ex vivo. As OR2AT4 is also expressed by epidermal keratinocytes, we hypothesized that it may modulate intraepidermal AMP synthesis, thereby contributing to skin microbiome management. Methods: We investigated this hypothesis in organ-cultured human skin in the presence of Sandalore® and antibiotics and evaluated epidermal production of two AMPs, LL37 (cathelicidin) and dermcidin (DCD), as well as OR2AT4, by quantitative immunohistomorphometry. Moreover, we quantified DCD secretion into the culture medium by ELISA and studied the effect of culture medium on selected bacterial and fungal strains. Results: Topical application of Sandalore®to organ-cultured human skin increased OR2AT4 protein expression, the number of DCD-positive intraepidermal cells, and DCD secretion into culture media, without significantly affecting epidermal LL37 expression. In line with the significantly increased secretion of DCD into the culture medium, we demonstrated, in a spectrophotometric assay, that application of conditioned media from Sandalore®-treated skin promotes Staphylococcus epidermidis, Malassezia restricta, and, minimally, Cutibacterium acnes and inhibits Staphylococcus aureus growth. Conclusion: In addition to demonstrating for the first time that DCD can be expressed by epidermal keratinocytes, our pilot study suggests that topical treatment of human skin with a cosmetic odorant (Sandalore®) has the potential to alter the composition of the human skin microbiome through the selective upregulation of DCD. If confirmed, Sandalore® could become an attractive adjuvant, nondrug treatment for dermatoses characterized by dysbiosis due to overgrowth of S. aureus and Malassezia, such as atopic dermatitis and seborrheic dermatitis.

294 Dermcidin: a new player in a familiar case of Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is an inflammatory skin disease with a multifactorial aetiology that involves a strict interplay between genetic factors, immune dysregulation and lifestyle. Familial forms represent 40% of the total HS cases and show an autosomal dominant mode of inheritance of the disease. By studying an HS family we found a rare DCD gene frameshift insertion in heterozygosis (rs538180888); DCD encodes for dermcidin (DCD), an antimicrobial peptide (AMP) produced by sweat glands. AMPs are considered key effectors of cutaneous innate immune responses and are normally constitutively expressed in human epithelia by keratinocytes, neutrophils, sebocytes or sweat glands; deregulation in the expression of AMPs, including DCD, may be associated with the etiology of inflammatory skin diseases, such as HS.

Dermcidin-derived polypeptides: DCD(86-103) induced inflammatory reaction in the skin by activation of mast cells via ST2

BackgroundPsoriasis is a chronic inflammatory disease. Mast cells are significantly increased and activated in the lesions of patients with psoriasis, contributing to psoriatic inflammation. Dermcidin (DCD) is a natural antibacterial peptide secreted by sweat glands and is usually transported to the epidermal surface by sweat. Whether DCD is involved in mast cell activation remains unclear and the mechanisms by which DCD is involved in skin inflammatory reactions require further investigation. MethodsWe investigated whether dermcidin-derived polypeptides DCD(86-103) activate mast cells and induce skin inflammatory reactions that contribute to psoriasis. Wild-type mice were treated with DCD(86-103) to observe the inflammatory reactions in the skin and cytokine release in vivo. The release of inflammatory mediators by mouse primary mast cells and LAD2 cells was measured in vitro. Molecular docking analysis, molecular dynamics simulation, and siRNA transfection were used to identify DCD(86-103). ResultsDCD(86-103) caused a skin inflammatory reaction in wild-type mice via cytokine release. Moreover, DCD(86-103) directly activated mast cells and induced cytokine release in vitro. ST2 may be a key receptor that mediates the activation effect of DCD(86-103) on mast cells leading to cytokine release. ConclusionDCD(86-103) may have induced an inflammatory reaction and participated in the occurrence and development of psoriasis.

LB869 Dermcidin derived polypeptides: DCD(86-103) induced inflammatory reaction in skin by activation mast cells via ST2

Psoriasis is a kind of chronic inflammatory skin disease. Mast cells significantly increase and activate in the lesions of psoriasis patients, which involves in psoriatic inflammation. Dermcidin (DCD) is a natural antibacterial peptide secreted by sweat glands and usually transported to the epidermal surface by sweat. Whether DCD is involved in mast cell activation is unclear. However, the mechanisms that DCD involved in skin inflammatory reaction needs to be investigated. To investigate whether Dermcidin derived polypeptides: DCD(86-103) activates MCs and induces skin inflammatory reaction contributing to psoriasis.

Preclinical Development of Seriniquinones as Selective Dermcidin Modulators for the Treatment of Melanoma.

The bioactive natural product seriniquinone was discovered as a potential melanoma drug, which was produced by the as-yet-undescribed marine bacterium of the rare genus Serinicoccus. As part of a long-term research program aimed at the discovery of new agents for the treatment of cancer, seriniquinone revealed remarkable in vitro activity against a diversity of cancer cell lines in the US National Cancer Institute 60-cell line screening. Target deconvolution studies defined the seriniquinones as a new class of melanoma-selective agents that act in part by targeting dermcidin (DCD). The targeted DCD peptide has been recently examined and defined as a “pro-survival peptide” in cancer cells. While DCD was first isolated from human skin and thought to be only an antimicrobial peptide, currently DCD has been also identified as a peptide associated with the survival of cancer cells, through what is believed to be a disulfide-based conjugation with proteins that would normally induce apoptosis. However, the significantly enhanced potency of seriniquinone was of particular interest against the melanoma cell lines assessed in the NCI 60-cell line panel. This observed selectivity provided a driving force that resulted in a multidimensional program for the discovery of a usable drug with a new anticancer target and, therefore, a novel mode of action. Here, we provided an overview of the discovery and development efforts to date.

Withdrawal

Diabetes is common in tobacco-consuming individuals, hypoxia-encountering people, and post-menopausal women. The mechanism behind diabetes-associated vascular-dysfunction remains speculative. Dermcidin (DCD), an 11 kDa-protein plays a detrimental role in acute myocardial-infarction through the impairment of endothelial-nitric-oxide-synthase (eNOS). DCD mediated genesis of diabetes has been manifested in human and rodent-models under various stress-conditions. Here, plasma levels of DCD have been significantly correlated with the diabetic-conditions in postmenopausal-women, in tobacco-consuming individuals and in hypoxia indicating a common pathway. In mice, DCD infusion augmented the blood glucose with a concomitant reduction of nitric oxide levels. DCD triggers the release of glucose from the liver/muscle/kidney and antagonizes the effects of insulin. This has been demonstrated by the glucose tolerance and insulin tolerance test. Herein our studies showed that DCD inhibited GLUT-4 and impaired NO production. We showed that tobacco consumption or hypoxia might provoke DCD-induced hyperglycemia by down-regulation of NO-signaling, GLUT4-function, and insulin sensitivity. Tobacco-induced DCD up-regulation has been shown in RT-PCR and qPCR results and DCD-induced lower insulin-sensitivity has been shown by Western-blot. The insulin, GLUT-4, and GANOS expression were missing in postmenopausal women due to DCD. Our FRET-imaging studies demonstrate that DCD-induced NO deregulation impairs cGMP-mediated cellular-signaling. Molecular-docking experiments (AUTODOCK/PATCHDOCK) decisively showed high-affinity binding of DCD to GLUT-4, insulin, and its receptor (Ectodomain1/2). Synergism of all these effects resulted in the breakdown of glucose homeostasis-machinery i.e. insulin-resistance, and further dermcidin induced NO/cGMP down-regulation in individuals under a variety of stressors.

Human Dermcidin Protects Mice Against Hepatic Ischemia-Reperfusion-Induced Local and Remote Inflammatory Injury.

BackgroundHepatic ischemia and reperfusion (I/R) injury is commonly associated with surgical liver resection or transplantation, and represents a major cause of liver damage and graft failure. Currently, there are no effective therapies to prevent hepatic I/R injury other than ischemic preconditioning and some preventative strategies. Previously, we have revealed the anti-inflammatory activity of a sweat gland-derived peptide, dermcidin (DCD), in macrophage/monocyte cultures. Here, we sought to explore its therapeutic potential and protective mechanisms in a murine model of hepatic I/R.MethodsMale C57BL/6 mice were subjected to hepatic ischemia by clamping the hepatic artery and portal vein for 60 min, which was then removed to initiate reperfusion. At the beginning of reperfusion, 0.2 ml saline control or solution of DCD (0.5 mg/kg BW) or DCD-C34S analog (0.25 or 0.5 mg/kg BW) containing a Cys (C)→Ser (S) substitution at residue 34 was injected via the internal jugular vein. For survival experiments, mice were subjected to additional resection to remove non-ischemic liver lobes, and animal survival was monitored for 10 days. For mechanistic studies, blood and tissue samples were collected at 24 h after the onset of reperfusion, and subjected to measurements of various markers of inflammation and tissue injury by real-time RT-PCR, immunoassays, and histological analysis.ResultsRecombinant DCD or DCD-C34S analog conferred a significant protection against lethal hepatic I/R when given intravenously at the beginning of reperfusion. This protection was associated with a significant reduction in hepatic injury, neutrophilic CXC chemokine (Mip-2) expression, neutrophil infiltration, and associated inflammation. Furthermore, the administration of DCD also resulted in a significant attenuation of remote lung inflammatory injury. Mechanistically, DCD interacted with epidermal growth factor receptor (EGFR), a key regulator of liver inflammation, and significantly inhibited hepatic I/R-induced phosphorylation of EGFR as well as a downstream signaling molecule, protein kinase B (AKT). The suppression of EGFR expression by transducing Egfr-specific shRNA plasmid into macrophages abrogated the DCD-mediated inhibition of nitric oxide (NO) production induced by a damage-associated molecular pattern (DAMP), cold-inducible RNA-binding protein, CIRP.ConclusionsThe present study suggests that human DCD and its analog may be developed as novel therapeutics to attenuate hepatic I/R-induced inflammatory injury possibly by impairing EGFR signaling.

Dermcidin Enhances the Migration, Invasion, and Metastasis of Hepatocellular Carcinoma Cells In Vitro and In Vivo

Background and AimsHepatocellular carcinoma (HCC) is a common primary liver neoplasm with high mortality. Dermcidin (DCD), an antimicrobial peptide, has been reported to participate in oncogenesis. This study assessed the effects and underlying molecular events of DCD overexpression and knockdown on the regulation of HCC progression in vitro and in vivo.MethodsThe serum DCD level was detected using enzyme-linked immunosorbent assay. DCD overexpression, knockdown, and Ras-related C3 botulinum toxin substrate 1 (Rac1) rescue were performed in SK-HEP-1 cells using plasmids. Immunofluorescence staining, quantitative PCR, and Western blotting were used to detect the expression of different genes and proteins. Differences in HCC cell migration and invasion were detected by Transwell migration and invasion assays. A nude mouse HCC cell orthotopic model was employed to verify the in vitro data.ResultsThe level of serum DCD was higher in patients with HCC and in SK-HEP-1 cells. DCD overexpression caused upregulation of DCD, fibronectin, Rac1, and cell division control protein 42 homologue (Cdc42) mRNA and proteins as well as actin-related protein 2/3 (Arp2/3) protein (but reduced Arp2/3 mRNA levels) and activated Rac1 and Cdc42. Phenotypically, DCD overexpression induced HCC cell migration and invasion in vitro, whereas knockout of DCD expression had the opposite effects. A Rac1 rescue experiment in DCD-knockdown HCC cells increased HCC cell migration and invasion and increased the levels of active Rac1/total Rac1, Wiskott-Aldrich syndrome family protein (WASP), Arp2/3, and fibronectin. DCD overexpression induced HCC cell metastasis to the abdomen and liver in vivo.ConclusionsDCD promotes HCC cell migration, invasion, and metastasis through upregulation of noncatalytic region of tyrosine kinase adaptor protein 1 (Nck1), Rac1, Cdc42, WASP, and Arp2/3, which induce actin cytoskeletal remodeling and fibronectin-mediated cell adhesion in HCC cells.

Cell surface GRP78 and Dermcidin cooperate to regulate breast cancer cell migration through Wnt signaling.

The heat shock protein GRP78 typically resides in the endoplasmic reticulum in normal tissues, but it has been shown to be expressed on the cell surface of several cancer cells, and some stem cells, where it can act as a signaling molecule by not-yet-fully defined mechanisms. Although cell surface GRP78 (sGRP78) has emerged as an attractive chemotherapeutic target, understanding how sGRP78 is functioning in cancer has been complicated by the fact that sGRP78 can function in a cell-context dependent manner, with a diverse array of reported binding partners, to regulate a variety of cellular responses. We had previously shown that sGRP78 was important in regulating pluripotent stem cell (PSC) functions, and hypothesized that embryonic-like mechanisms of GRP78 were critical to regulating aggressive breast cancer cell functions. Here, using proteomics we identify Dermcidin (DCD) as a novel sGRP78 binding partner common to both PSCs and breast cancer cells. We show that GRP78 and DCD cooperate to regulate stem cell and cancer cell migration that is dependent on the cell surface functions of these proteins. Finally, we identify Wnt/β-catenin signaling, a critical pathway in stem cell and cancer cell biology, as an important downstream intermediate in regulating this migration phenotype.

Serum markers improve current prediction of metastasis development in early-stage melanoma patients: a machine learning-based study.

Metastasis development represents an important threat for melanoma patients, even when diagnosed at early stages and upon removal of the primary tumor. In this scenario, determination of prognostic biomarkers would be of great interest. Serum contains information about the general status of the organism and therefore represents a valuable source for biomarkers. Thus, we aimed to define serological biomarkers that could be used along with clinical and histopathological features of the disease to predict metastatic events on the early‐stage population of patients. We previously demonstrated that in stage II melanoma patients, serum levels of dermcidin (DCD) were associated with metastatic progression. Based on the relevance of the immune response on the cancer progression and the recent association of DCD with local and systemic immune response against cancer cells, serum DCD was analyzed in a new cohort of patients along with interleukin 4 (IL‐4), IL‐6, IL‐10, IL‐17A, interferon γ (IFN‐γ), transforming growth factor‐β (TGF‐ β), and granulocyte–macrophage colony‐stimulating factor (GM‐CSF). We initially recruited 448 melanoma patients, 323 of whom were diagnosed as stages I‐II according to AJCC. Levels of selected cytokines were determined by ELISA and Luminex, and obtained data were analyzed employing machine learning and Kaplan–Meier techniques to define an algorithm capable of accurately classifying early‐stage melanoma patients with a high and low risk of developing metastasis. The results show that in early‐stage melanoma patients, serum levels of the cytokines IL‐4, GM‐CSF, and DCD together with the Breslow thickness are those that best predict melanoma metastasis. Moreover, resulting algorithm represents a new tool to discriminate subjects with good prognosis from those with high risk for a future metastasis.

Plasma dermcidin levels in acne patients, and the effect of isotretinoin treatment on dermcidin levels.

Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit. Dermcidin (DCD) is an antimicrobial peptide released from eccrine sweat glands and sebaceous glands. Studies investigating the role of DCD expression in acne development are scarce. The aim of this study was to determine the relationship between DCD expression and acne vulgaris and the effect of oral isotretinoin treatment on DCD levels. Two groups (one patient group and one control group) were included in the study. The patient group consisted of 30 patients with acne vulgaris who were given oral isotretinoin treatment for 6 months until the cumulative dose was attained. Plasma DCD levels were investigated before and 6 months after treatment. The control group comprised 30 volunteer individuals without acne vulgaris or any inflammatory dermatosis. Of the patients, 24 (80%) had Grade 3, 3 (10%) had Grade 1, and 3 (10%) had Grade 4 acne vulgaris, as determined according to the Pillsbury scoring method. The DCD levels in the control group were significantly higher than those in pretreatment patients (39.53 ± 20.2 vs. 28.60 ± 20.12, p = .004). Additionally, pretreatment DCD levels were significantly increased after 6 months of isotretinoin treatment in the patient group (28.60 ± 20.12 vs. 35.07 ± 24.02, p = .012). The mean pretreatment global acne grading system score of 20.86 ± 4.43 was decreased to 5.17 ± 1.91 in patients after treatment (p < .001). This study indicated that DCD plays an important role in the pathogenesis of acne. It demonstrates anti-inflammatory properties in acne vulgaris. Moreover, it was shown that isotretinoin treatment may improve acne vulgaris by increasing DCD levels.

Lipid Bilayer Composition Influences the Activity of the Antimicrobial Peptide Dermcidin Channel

Antimicrobial peptides (AMPs) carry great potential as new antibiotics against “superbugs.” Dermcidin (DCD), a broad-spectrum AMP in human sweat, has been recently crystallized in its oligomeric state and showed channel-like properties. In this work, we performed multiscale molecular dynamics simulations to study how the membrane composition influences the behavior of a transmembrane pore formed by the DCD oligomer in the hope of revealing the origin of the membrane selectivity of this AMP toward bacteria. Our results indicate that bilayers composed of various lipids (DMPC, DPPC, and DSPC) with different thicknesses result in different orientations of the DCD oligomer when embedded in lipid bilayers. The thicker the bilayer, the less tilted the channel. Cholesterol makes the bilayers more rigid and thicker, which also affects the orientation of the channel. Furthermore, we observed that the predicted conductance of the channel from computational electrophysiology simulations is related to its orientation in the lipid bilayer: the larger the tilt, the larger the conductance. Our results indicate that the membrane composition has a significant influence on the activity of the DCD channel, with thicker, cholesterol-rich membranes showing lower conductance than that of thinner membranes.

Abstract 1990: Aberrant cell surface expression of GRP78 in breast cancer cells marks a stem-like population that has increased metastatic potential in vivo

Abstract Reliable approaches to identify and target stem-cell mechanisms that mediate aggressive cancer could have great therapeutic value, based on the growing evidence of embryonic signatures in metastatic cancers. However, how to best identify and target stem-like mechanisms aberrantly utilized by cancer cells has been challenging. We harnessed the power of induced pluripotent stem cells (iPSCs) to identify embryonic mechanisms exploited by cancer. A screen comparing the cell surface proteome of iPSCs and breast cancer cells identified GRP78, a heat shock protein that is normally ER-restricted, but has been shown to be aberrantly expressed on the cell surface of several cancers, where it can act as a signaling molecule by poorly understood mechanisms. Although cell surface GRP78 (sGRP78) has emerged as an attractive chemotherapeutic target, understanding how sGRP78 is functioning in cancer has been complicated by the fact that GRP78 can function to regulate a variety of cellular responses, using a diverse array of reported binding partners, which can vary by cell type. Therefore, without insight into the specific GRP78-dependent mechanisms that are responsible for mediating aggressive cancer, it will be difficult to determine how to best target GRP78. We have discovered that (1) sGRP78 is expressed on iPSCs (but not their somatic parental populations) and plays an important role in reprogramming, (2) sGRP78 promotes cellular functions such as proliferation/survival and migration in both stem cells and breast cancer cells (3) overexpression of GRP78 in breast cancer cells leads to an induction of a previously established CD24-/CD44+ 'cancer stem cell' (CSC) population (4) sGRP78+ breast cancer cell populations are enriched for genes involved in stemness and appear to be a subset of previously established CSCs (5) sGRP78+ breast cancer cell populations show a significantly enhanced ability to seed metastatic organ sites in vivo (6) GRP78 interacts with Dermcidin (DCD) at the cell surface of cancer cells and iPSCs, where it is important in regulating stem cell and cancer cell migration and survival/proliferation. These collective findings suggest that sGRP78 marks a stem-like population in breast cancer cells that has increased metastatic potential in vivo, and that sGRP78 and DCD cooperate to regulate key cellular functions important in mediating tumorigenesis. Overall, this work has implications for understanding how cancer cells exploit embryonic-like mechanisms, which could provide novel strategies for chemotherapeutic targeting of aggressive breast cancer cell populations. Citation Format: Tyson W. Lager, Henry C. Conner, Ian H. Guldner, Michael Z. Wu, Yuriko Hishida, Tomoaki Hishida, Sergio Ruiz, Amanda E. Yamasaki, Juan Carlos Izpisua Belmonte, Peter C. Gray, Jonathan A. Kelber, Siyuan Zhang, Athanasia D. Panopoulos. Aberrant cell surface expression of GRP78 in breast cancer cells marks a stem-like population that has increased metastatic potential in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1990.

The Role of Dermcidin in the Diagnosis and Staging of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a major contributor to cancer-related deaths due to its often late stage diagnosis. Our previous study showed that dermcidin (DCD) may have the potential to be used as a serum biomarker for HCC for more timely diagnoses. In this study, we measured serum DCD and alpha-fetoprotein (AFP) levels in 87 HCC patients; 33 liver cirrhosis (LC); and 44 normal controls (NC), evaluated the relationship between DCD levels and clinicopathological parameters. Serum DCD levels in HCC patients (27.03 ng/mL) were significantly higher than in LC patients (24.78 ng/mL, p < 0.05), and NC subjects (18.98 ng/mL, p < 0.001). The optimum cutoff values were 25.75 ng/mL for DCD and 9.86 ng/mL for AFP. DCD had a greater area under the receiver operating characteristic curve (AUC) for differentiating HCC from the controls than AFP (AUC = 0.769 vs. 0.729, respectively). Importantly, our cohort revealed that serum DCD levels were positively correlated with metastasis in HCC patients versus HCC patients without metastatic disease (32.31 vs. 23.95, p < 0.001). Western blot results showed that DCD expression was significantly upregulated in seven tumor tissues compared with the noncancerous adjacent tissues. Immunohistochemistry performed in four paired samples confirmed the upregulation of DCD expression in the tumor tissues. Our results showed that serum DCD levels were significantly increased in HCC patients and in cancerous tissue. DCD could potentially be used as a biomarker for the diagnosis of HCC.

The Human Antimicrobial Peptides Dermcidin and LL-37 Show Novel Distinct Pathways in Membrane Interactions.

Mammals protect themselves from inflammation triggered by microorganisms through secretion of antimicrobial peptides (AMPs). One mechanism by which AMPs kill bacterial cells is perforating their membranes. Membrane interactions and pore formation were investigated for α-helical AMPs leading to the formulation of three basic mechanistic models: the barrel stave, toroidal, and carpet model. One major drawback of these models is their simplicity. They do not reflect the real in vitro and in vivo conditions. To challenge and refine these models using a structure-based approach we set out to investigate how human cathelicidin (LL-37) and dermcidin (DCD) interact with membranes. Both peptides are α-helical and their structures have been solved at atomic resolution. DCD assembles in solution into a hexameric pre-channel complex before the actual membrane targeting and integration step can occur, and the complex follows a deviation of the barrel stave model. LL-37 interacts with lipids and shows the formation of oligomers generating fibril-like supramolecular structures on membranes. LL-37 further assembles into transmembrane pores with yet unknown structure expressing a deviation of the toroidal pore model. Both of their specific targeting mechanisms will be discussed in the context of the “old” models propagated in the literature.

Structural basis for the bacterial membrane insertion of dermcidin peptide, DCD-1L

Human dermcidin (DCD) is an antimicrobial peptide secreted constitutively by sweat glands. The anionic derivative, DCD-1L, comprises of the N-terminal 47 residues of DCD and one additional leucine residue. A previous NMR structure of DCD-1L in 50% TFE showed a partial helical conformation, and its crystal structure in the presence of Zn2+ outlined a hexameric linear α-helical bundle. Three different models to describe membrane insertion were proposed but no conclusion was drawn. In the current study, the NMR structure of DCD-1L in SDS micelles showed an “L-shaped” molecule with three fully formed α-helices connected by flexible turns. Formation of these helices in DCD-1L in the presence of POPG vesicles suggests that the acidic C-terminal region of DCD-1L can suppress the binding of DCD-1L to POPG vesicles at basic but not acidic pH. Mutation of charged residues on the N-terminal and C-terminal regions of DCD-1L cause differences in POPG binding, suggesting distinct functional roles for these two regions. Charged residues from these two regions are also found to differentially affect Zn2+ coordination and aggregation of DCD-1L in the absence or presence of SDS, as monitored by 1D NMR. Our data agrees with one of the three models proposed.

A novel protein peptide associated with ischemic heart disease: dermcidin

Dermcidin (DCD) was found in isolated human skin sweat glands with antimicrobial effect, and was defined as a kind of new small molecule antimicrobial peptide. It was a part of human sweat glands in the skin as the immune system's innate defense. With the studies of DCD, its extensive biological functions are gradually discovered. Since 2010, a number of studies have shown that DCD may be a new risk factor for atherosclerosis. And the role of DCD in ischemic heart disease has drawn increasing attention in particular its relationship with insulin secretion and glycemic control, nitric oxide (NO) synthesis and hypertension, platelet aggregation and acute myocardial infarction (AMI). In those experiments, it was also confirmed that aspirin had antagonistic and reverse effects on various biological functions of DCD. Further research on the role of DCD in cardiovascular and cerebrovascular diseases may lead to the prevention, early warning, prognosis evaluation and treatment breakthrough of cardiovascular and cerebrovascular events.