Podoplanin Expression Research Articles

Podoplanin is Responsible for the Distinct Blood and Lymphatic Capillaries

IntroductionControlling the formation of blood and lymphatic vasculatures is crucial for engineered tissues. Although the lymphatic vessels originate from embryonic blood vessels, the two retain functional and physiological differences even as they develop in the vicinity of each other. This suggests that there is a previously unknown molecular mechanism by which blood (BECs) and lymphatic endothelial cells (LECs) recognize each other and coordinate to generate distinct capillary networks.MethodsWe utilized Matrigel and fibrin assays to determine how cord-like structures (CLS) can be controlled by altering LEC and BEC identity through podoplanin (PDPN) and folliculin (FLCN) expressions. We generated BECΔFLCN and LECΔPDPN, and observed cell migration to characterize loss lymphatic and blood characteristics due to respective knockouts.ResultsWe observed that LECs and BECs form distinct CLS in Matrigel and fibrin gels despite being cultured in close proximity with each other. We confirmed that the LECs and BECs do not recognize each other through paracrine signaling, as proliferation and migration of both cells were unaffected by paracrine signals. On the other hand, we found PDPN to be the key surface protein that is responsible for LEC-BEC recognition, and LECs lacking PDPN became pseudo-BECs and vice versa. We also found that FLCN maintains BEC identity through downregulation of PDPN.ConclusionsOverall, these observations reveal a new molecular pathway through which LECs and BECs form distinct CLS through physical contact by PDPN which in turn is regulated by FLCN, which has important implications toward designing functional engineered tissues.

Podoplanin expression in lymph node metastases of head and neck cancer and cancer of unknown primary patients.

Head and neck squamous cell carcinomas (HNSCCs) are cancers with generally poor prognosis. Outcomes have not improved in decades, with more than half of the patients presenting with lymph node metastases at the time of diagnosis. A unique subtype of HNSCC, cancer of unknown primary of the head and neck (HNCUP) is associated with a poor outcome. Increased expression of the D2-40 gene (podoplanin) has been described for several human malignancies and has been associated with increased metastatic potential of cancer cells. In order to examine the role of podoplanin in lymph node metastasis of HNSCC generally and HNCUP specifically, we evaluated the prognostic impact of podoplanin expression in HNSCC- (n = 68) and HNCUP-associated lymph node metastases (n = 30). The expression of podoplanin was analyzed by immunohistochemical staining of lymph node tissue samples and correlated with clinical and histopathological data. We found a non-significant tendency towards a higher podoplanin expression in HNCUP compared to HNSCC lymph node metastases and a significant correlation between a high podoplanin expression and advanced node-stage classification. Podoplanin expression had no significant impact on overall survival for both groups and did not correlate with human papillomavirus tumor status. Taken together, our results suggest that upregulation of podoplanin may be associated with a stimulation of lymphatic metastasis in head and neck cancer.

Study of Podoplanin Expression in Head and Neck Squamous Cell Carcinoma.

Background & Objective:Head and Neck Squamous cell carcinoma (HNSCC) is one of the leading cancers worldwide. Cervical lymph node metastasis is the most adverse prognostic factor for patients with HNSCC. As there are no reliable factors in predicting lymph node metastasis, recent researchers focus on identifying various metastasis markers that will aid treatment selection. Podoplanin is a recent marker strongly associated with lymph node metastasis, aggressive tumor behavior, and poor prognosis. The expression of podoplanin in human squamous cell cancers and its association with cancer cell motility suggest a possibility that it could be used as a biomarker to predict lymph node metastasis. To study the expression of podoplanin in head and neck squamous cell carcinoma, determine its association with clinicopathological variables, and predict its use as a biomarker in predicting lymph node metastasis. Methods:The present study was conducted in a tertiary care hospital. Podoplanin expression was studied in 45 cases of HNSCC and its association with clinicopathological variables. The predictive power of podoplanin was further analyzed using univariate and multivariate logistic regression analysis. The positive and negative predictive values of podoplanin were determined concerning the presence or absence of lymph node metastasis.Results:Podoplanin expression is significantly associated with histological grade (P=0.03) and lymph node metastasis (P=0.01). In logistic regression analysis, podoplanin expression (Odds Ratio: 5.66, Confidence Interval: 1.23 -25.87, P=0.02) was a significant independent predictor of lymph node metastasis. Conclusion: Our study demonstrates that podoplanin provides prognostic information and predicts lymph node metastasis which was consistent with our studies in the literature. Thus, podoplanin may help better stratify patients selected for elective neck node dissection in early tumor stages and clinically negative regional disease.

Increased expression of podoplanin, a marker of dilated lymphatic vessels in duodenal biopsies is an independent predictor of three-month mortality in patients with cirrhosis

Increased expression of podoplanin, a marker of dilated lymphatic vessels in duodenal biopsies is an independent predictor of three-month mortality in patients with cirrhosis

Role of podoplanin, E-cadherin, Ki-67 in the dissemination of tumor cells in ovarian surface epithelial carcinoma-An immunohistochemical study

Background/aimTo understand the biological behaviour, ovarian carcinoma should be approached as a complex tissue composed of tumor cells, ECM proteins, endothelial cells, fibroblasts, inflammatory cells and lymphatics. We aimed to investigate the role of proliferation index of the tumor cells, cell adheshion molecules and lymphangiogenesis in the dissemination of tumor in ovarian surface epithelial carcinomas using suitable antibodies. Materials and methodsFifty-nine cases of ovarian carcinoma were assessed immunohistochemically to quantify the intratumoral and peritumoral LVD, podoplanin expression in stroma, E-cadherin expression and proliferation index of the tumor cells. Descriptive statistics were done stratifying the cases into early stage(FIGO-I) and advanced stage (FIGO-II,III,IV).Receiver operating curve was applied to determine the cut off of intratumoral LVD, peritumoral LVD, Ki-67 to discriminate early stage and advanced stage disease and the cut offs were validated by generating regression model. ResultsIntratumoral LVD (p = 0.001), peritumoral LVD (p = 0.000), high Ki-67 (p = 0.000), podoplanin expressing cancer associated fibroblasts (p = 0.002) and macrophages expressing podoplanin (p = 0.003) were significantly associated with advanced stage disease. Intratumoral LVD, peritumoral LVD and Ki67 at cut offs of 3.5, 9.5 and 30 % emerged as discriminators of early stage disease from advanced stage disease by ROC curve analysis. Peritumoral LVD > 9.5 had the highest odds of advanced disease (OR-33.948, CI-4.631-38.622). ConclusionOSECs with intratumoral LVD > 3.5, peritumoral LVD > 9.5 and Ki-67 > 30 % should be considered for aggressive chemotherapy and frequent follow-up. Peritumoral LVD and podoplanin expression in components of tumor stroma have a determinant role in tumor dissemination in OSEC.

Oral squamous cell carcinomas: a histopathological review of multiple cases from Western Romania.

Malignant tumors of the oral cavity have a growing incidence, most being squamous cell carcinomas, generally called oral cancers (OCs), clinically detected at various stages of natural evolution. The increased incidence in Romania in recent years and the lack of conclusive data have led to the development of this study. The main purpose of this study was to assess the molecular profile of tumors, the types of blood vessels associated with the tumor, and expression of tumor immunomarkers. Regarding morphological findings, focal epithelial hyperplasia, dysplastic lesions, typical mitoses, perineural invasion, parakeratosis and keratosis beads, intracytoplasmic keratinization were observed. Microvascular density was higher in the tumor area compared to the peritumoral area. Lymphovascular invasion was identified in 13% of cases, which also presented regional lymph node metastases. Podoplanin expression was identified in 79% of cases which were tested positive for the D2-40 immunomarker. All p53-positive cases co-expressed epidermal growth factor receptor (EGFR), half of the EGFR-positive cases co-expressed p53, and co-expression of CD117 and p63 was identified in 80% of EGFR-positive/cytokeratin 5 (CK5)-positive cases being proposed the basal-like subtype of OCs, defined as EGFR-positive/CK5-positive, CD117-positive and p63-positive. Results support the need for molecular classification of OCs based on of tumor immunomarker expression and gene analysis.

The Role of Podoplanin in the Immune System and Inflammation.

Podoplanin is a small cell-surface mucin-like glycoprotein that participates in multiple physiological and pathological processes. Podoplanin exerts an important function in the immune response and is upregulated in fibroblasts, macrophages, T helper cells, and epithelial cells during inflammation. Herein, we summarize the latest knowledge on the functional expression of podoplanin in the immune system and review the contribution of podoplanin to several inflammatory diseases. Furthermore, we discuss podoplanin as a novel therapeutic target for various inflammatory diseases.

Effect of Anti-Podoplanin on Malignant Glioma Cell Viability, Invasion and Tumor Cell-Induced Platelet Aggregation

The transmembrane receptor podoplanin (PDPN) is a platelet aggregation-inducing factor, which is widely expressed in various malignant tumors such as squamous cell carcinomas, mesotheliomas, glioblastomas. Podoplanin regulates a pathway leading to cell invasion and migration. Glioblastoma multiforme (GBM) is the most aggressive and invasive tumor of the central nervous system. A high level of PDPN expression has been reported to be associated with reduced survival, cancer aggression and migration. Aim of study to determine the effect of anti-podoplanin antibody on cell-platelet aggregation, cell invasion and viability in Uppsala 87 malignant glioma (U87MG) cell lines. The expression of podoplanin on U87MG cells was measured using flowcytometry. The dimethyl-thiazol diphenyl-tetrazolium bromide (MTT) assay was used to measure U87MG cell proliferation after treatment by anti-podoplanin monoclonal antibody (NZ-1.3). The invasion of cancer cells was assessed by using a novel microfluidic based assay. The results show reduction of cell viability and cell migration after treatment with anti-podoplanin antibody. After co- treatment of U87MG cells and platelets with and without anti-podoplanin antibody, the cell-platelet aggregation was significantly reduced in anti-podoplanin treated cell. Podoplanin is involved in aggregation of gliobastoma cells, and their viability and invasion and its neutralizing antibody can inhibit this process. So, blocking of podoplanin may be representing a promising therapeutic approach to glioblastoma multiform cancer therapy.

Podoplanin Expression Independently and Jointly with Oral Epithelial Dysplasia Grade Acts as a Potential Biomarker of Malignant Transformation in Oral Leukoplakia.

Our aim was to evaluate the expression of biomarkers, CD44v6, CD147, EGFR, p53, p63, p73, p16, and podoplanin in oral leukoplakias (OL) and to assess their potential for prediction of malignant transformation (MT). We analyzed the expression of CD44v6, CD147, EGFR, p53, p63, p73, p16, and podoplanin by immunohistochemistry in 52 OL, comprised of 41 low-grade (LG) dysplasia and 11 high-grade (HG) cases. Twelve healthy normal tissues (NT) were also included. Univariate and multivariate analysis were performed to evaluate any association with MT. Variable expression among the studied markers was observed, with a significant increase of high expression from NT to LG and HG cases in CD44v6 (p = 0.002), P53 (p = 0.002), P73 (p = 0.043), and podoplanin (p < 0.001). In multivariate analysis, cases with high podoplanin score showed a significant increased risk of MT (HR of 10.148 (95% CI of 1.503–68.532; p = 0.017). Furthermore, podoplanin combined with binary dysplasia grade obtained a HR of 10.238 (95% CI of 2.06–50.889; p = 0.004). To conclude, CD44v6, p53, p73, and podoplanin showed an increasing expression along the natural history of oral carcinogenesis. Podoplanin expression independently or combined with dysplasia grade could be useful predictive markers of MT in OL.

Analysis and comparison of podoplanin (D2-40) and p53 as potential predictors of malignant progression in proliferative verrucous leukoplakia (PVL)

<h3>Introduction</h3> p53 overexpression is well documented in premalignant lesions of the oral cavity. However, recent studies have shown increased expression of podoplanin (D2-40) in oral dysplasia. This study aims to evaluate the efficacy of both markers in predicting malignant transformation in cases of proliferative verrucous leukoplakia (PVL), a recalcitrant oral premalignant condition with a high rate of malignant transformation. <h3>Materials and methods</h3> With IRB approval the UF archives were searched from 1994-2019 for cases with clinical diagnosis of PVL with at least one biopsy and follow-up of at least 3 years. Included cases were tested for IHC reactivity to p53 and D2-40. Reactivity was evaluated for basal cell layer nuclear positivity to p53 and cytoplasmic positivity to D2-40. Results for both tests were recorded as either >25% or <25% positivity in the basal cell layer. <h3>Results</h3> A total of 17 cases were included. The mean age was 63.11 years and 76.4% of the patients were females. Locations included gingiva (59%), tongue (17%), buccal mucosa (12%), palate and floor of the mouth (6% each). The histological diagnoses included verruco-papillary hyperkeratosis/verrucous hyperplasia (59%), atypia/dysplasia (18%), hyperkeratosis (17%), and atypical epithelial proliferation (6%). Of the included cases, 7 (41%) subsequently developed malignancy. There was no statistically significant difference in terms of age, gender, location, or histologic diagnosis regarding either p53 or D2-40 positivity. There was no significant difference between p53 positivity between cases with or without malignant transformation; however, cases with subsequent malignant transformation demonstrated significantly higher positivity to D2-40 than those that did not transform (<i>p=0.006</i>, chi-square). <h3>Conclusion</h3> D2-40 IHC testing was more useful in predicting malignant transformation than p53 in this small sample of PVL cases. Additional larger scale studies will likely confirm utility of D2-40 IHC testing in predicting PVL progression.

The Role of CD200-CD200 Receptor in Human Blood and Lymphatic Endothelial Cells in the Regulation of Skin Tissue Inflammation.

CD200 is a cell membrane glycoprotein that interacts with its structurally related receptor (CD200R) expressed on immune cells. We characterized CD200–CD200R interactions in human adult/juvenile (j/a) and fetal (f) skin and in in vivo prevascularized skin substitutes (vascDESS) prepared by co-culturing human dermal microvascular endothelial cells (HDMEC), containing both blood (BEC) and lymphatic (LEC) EC. We detected the highest expression of CD200 on lymphatic capillaries in j/a and f skin as well as in vascDESS in vivo, whereas it was only weakly expressed on blood capillaries. Notably, the highest CD200 levels were detected on LEC with enhanced Podoplanin expression, while reduced expression was observed on Podoplanin-low LEC. Further, qRT-PCR analysis revealed upregulated expression of some chemokines, including CC-chemokine ligand 21 (CCL21) in j/aCD200+ LEC, as compared to j/aCD200− LEC. The expression of CD200R was mainly detected on myeloid cells such as granulocytes, monocytes/macrophages, T cells in human peripheral blood, and human and rat skin. Functional immunoassays demonstrated specific binding of skin-derived CD200+ HDMEC to myeloid CD200R+ cells in vitro. Importantly, we confirmed enhanced CD200–CD200R interaction in vascDESS in vivo. We concluded that the CD200–CD200R axis plays a crucial role in regulating tissue inflammation during skin wound healing.

Expression Profile of CD157 Reveals Functional Heterogeneity of Capillaries in Human Dermal Skin

CD157 acts as a receptor, regulating leukocyte trafficking and the binding of extracellular matrix components. However, the expression pattern and the role of CD157 in human blood (BEC) and the lymphatic endothelial cells (LEC) of human dermal microvascular cells (HDMEC), remain elusive. We demonstrated constitutive expression of CD157 on BEC and LEC, in fetal and juvenile/adult skin, in situ, as well as in isolated HDMEC. Interestingly, CD157 epitopes were mostly localized on BEC, co-expressing high levels of CD31 (CD31High), as compared to CD31Low BEC, whereas the podoplanin expression level on LEC did not affect CD157. Cultured HDMEC exhibited significantly higher numbers of CD157-positive LEC, as compared to BEC. Interestingly, separated CD157− and CD157+ HDMEC demonstrated no significant differences in clonal expansion in vitro, but they showed distinct expression levels of cell adhesion molecules, before and after cytokine stimulation in vitro. In particular, we proved the enhanced and specific adherence of CD11b-expressing human blood myeloid cells to CD157+ HDMEC fraction, using an in vitro immune-binding assay. Indeed, CD157 was also involved in chemotaxis and adhesion of CD11b/c monocytes/neutrophils in prevascularized dermo–epidermal skin substitutes (vascDESS) in vivo. Thus, our data attribute specific roles to endothelial CD157, in the regulation of innate immunity during inflammation.

Metabolic reprogramming of synovial fibroblasts in osteoarthritis by inhibition of pathologically overexpressed pyruvate dehydrogenase kinases

Osteoarthritis (OA) is the most common degenerative joint disease and a major cause of age-related disability worldwide, mainly due to pain, the disease's main symptom. Although OA was initially classified as a non-inflammatory joint disease, recent attention has been drawn to the importance of synovitis and fibroblast-like synoviocytes (FLS) in the pathogenesis of OA. FLS can be divided into two major populations: thymus cell antigen 1 (THY1)- FLS are currently classified as quiescent cells and assumed to destroy bone and cartilage, whereas THY1+ FLS are invasively proliferative cells that drive synovitis. Both THY1- and THY1+ FLS share many characteristics with fibroblast-like progenitors – mesenchymal stromal cells (MSC). However, it remains unclear whether synovitis-induced metabolic changes exist in FLS from OA patients and whether metabolic differences may provide a mechanistic basis for the identification of approaches to precisely convert the pathologically proliferative synovitis-driven FLS phenotype into a healthy one. To identify novel pathological mechanisms of the perpetuation and manifestation of OA, we analyzed metabolic, proteomic, and functional characteristics of THY1+ FLS from patients with OA. Proteome data and pathway analysis revealed that an elevated expression of pyruvate dehydrogenase kinase (PDK) 3 was characteristic of proliferative THY1+ FLS from patients with OA. These FLS also had the highest podoplanin (PDPN) expression and localized to the sublining but also the lining layer in OA synovium in contrast to the synovium of ligament trauma patients. Inhibition of PDKs reprogrammed metabolism from glycolysis towards oxidative phosphorylation and reduced FLS proliferation and inflammatory cytokine secretion. This study provides new mechanistic insights into the importance of FLS metabolism in the pathogenesis of OA. Given the selective overexpression of PDK3 in OA synovium and its restricted distribution in synovial tissue from ligament trauma patients and MSC, PDKs may represent attractive selective metabolic targets for OA treatment. Moreover, targeting PDKs does not affect cells in a homeostatic, oxidative state. Our data provide an evidence-based rationale for the idea that inhibition of PDKs could restore the healthy THY1+ FLS phenotype. This approach may mitigate the progression of OA and thereby fundamentally change the clinical management of OA from the treatment of symptoms to addressing causes.

Clinical significance of CD34, podoplanin and Ki-67 expression in patients with locally advanced squamous cell cervical carcinoma

The aim of the study was to assess immunohistochemical CD34, podoplanin and Ki-67 expression in cervical tumour of patients with cervical squamous cell carcinoma (SCC) staged IIB and IIIB, a relationship with selected clinical and histological parameters and its prognostic significance. This prospective study included 52 patients. Microvessel density (MVD) by CD34, lymphatic vessel density (LVD) by podoplanin and the Ki-67 index in specimens from paraffin blocks with cervical SCC tissues were examined. The relationship between these data and selected clinical and histological parameters was analysed. Positive correlation of MVD and the Ki-67 index was observed. No correlation was observed for MVD, LVD and the Ki-67 index in the tumour with staging, grading, length of treatment and squamous cell carcinoma antigen (SCC-Ag) concentration before and after treatment. The expression of MVD, LVD and the Ki-67 index in cervical SCC did not contribute to the risk of relapse and cancer-related death. No relationship was found for MVD, LVD and the Ki-67 index in cervical tumour of patients with locally advanced cervical SCC with staging, grading and serum SCC-Ag level. MVD, LVD and the Ki-67 index in the tumour did not contribute to the risk of relapse or cervical SCC-related death. Impact Statement What is already known on this subject? In many patients, invasive cervical squamous cell carcinoma (SCC) is diagnosed in a locally advanced stage, when the prognosis depends on many well-known factors connected with tumour biology, staging and general condition of the patient. Despite numerous studies, the value of immunohistochemical CD34, podoplanin and Ki-67 expression in cervical tumour of these patients is still not well defined. What do the results of this study add? In our prospective study, no relationship for microvessel density (MVD), lymphatic vessel density (LVD) and the Ki-67 index in cervical tumour of patients with locally advanced cervical SCC with staging, grading and serum squamous cell carcinoma antigen (SCC-Ag) level was found. Additionally, MVD, LVD and the Ki-67 index in the tumour did not contribute to the risk of relapse or cervical SCC-related death. What are the implications of these findings for clinical practice and/or further research? Our study underlines the limited value of immunohistochemical CD34, podoplanin and Ki-67 expression in cervical tumour of patients with locally advanced cervical SCC. Further research should be focussed on identifying and validating novel prognostic and predictive factors.

Differential expression of podoplanin in metastatic lymph node is associated with extranodal extension in oropharyngeal cancer

This study aimed to investigate the spatial distribution and clinical significance of podoplanin expression in the metastatic lymph nodes of oropharyngeal squamous cell carcinomas (OPSCCs). The immunohistochemical podoplanin expression in the metastatic lymph nodes was evaluated in the pathologic specimens of 47 consecutive OPSCC patients. Clinicopathologic factors, including podoplanin expression and extranodal extension (ENE) status, were analyzed. Podoplanin was significantly expressed in the perinodal stroma (p = 0.001), and the average score of podoplanin was higher (p = 0.008) in ENE-positive lymph nodes than ENE-negative lymph nodes, although intranodal podoplanin expression did not differ significantly between the groups. Multivariable analysis revealed perinodal podoplanin expression as an independent marker of ENE in all the patients and the human papilloma virus (HPV)-positive group (p = 0.007 and p = 0.018, respectively). Podoplanin is differentially expressed in the metastatic lymph nodes in OPSCC, and its expression in perinodal stroma is associated with ENE, suggesting that podoplanin can be used clinically as a diagnostic biomarker.

Expression of Podoplanin in Hepatocellular Carcinoma in a Sample of Egyptian Population – Immunohistopathological Study

BACKGROUND: Hepatocellular carcinoma (HCC) is a highly incident malignancy with a dreadful prognosis. It evolves through a multistep process, with a contribution from different stromal cells like cancer associated fibroblasts. Podoplanin is a glycoprotein that influences epithelial mesenchymal interplay facilitating the tumor invasion. AIM: The aim of the study was to evaluate the immunohistochemical expression of Podoplanin in HCC in cancer associated fibroblasts (CAFs) and malignant hepatocytes as well as assessing the lymphovascular density, and correlating them with the clinicopathological parameters. METHODS: Sixty formalin-fixed paraffin-embedded HCC tissue blocks were retrieved from the pathology Department of the National Hepatology and Tropical Medicine Research Institute and Kasr Al-aini Hospital during the period of January 2012 till December 2019. The specimens were obtained through partial or total hepatectomy inclusion criteria included HCC cases obtained through resection type biopsy and those having no history of pre-operative cancer therapy, while cases with insufficient data, core biopsy, and marked necrosis were excluded from the study. Tumor tissue blocks were immunostained for Podoplanin and its expression was interpreted in lymphatic vessels, CAFs, and malignant hepatocytes. RESULTS: Podoplanin expression in CAFs and malignant hepatocytes was detected in the majority of HCC cases (81.7%) and (88.3%), respectively. The malignant hepatocytes showed increased expression of Grade 1 immunostaining (36.7%). High lymphovascular density was detected over the majority of the cases (73.3%). Podoplanin expression was significantly correlated with higher mean age, male gender, presence of viral infection, cirrhosis, and higher tumor grade. Unifocal tumor mass, tumor size &lt;5 cm, and presence of invasion showed a significant correlation with Podoplanin in malignant hepatocytes and CAFs for the formers and the later, respectively. CONCLUSION: Podoplanin is highly expressed in HCC, which could be used as a prognostic marker for lymphangiogenesis. Furthermore, within the malignant hepatocytes and CAFs suggesting a role in hepatocellular tumorigenesis. Podoplanin targeted therapy can be investigated to slow down the tumor progression and metastasis.

Lymphangiogenesis contributes to exercise-induced physiological cardiac growth

BackgroundPromoting cardiac lymphangiogenesis exerts beneficial effects for the heart. Exercise can induce physiological cardiac growth with cardiomyocyte hypertrophy and increased proliferation markers in cardiomyocytes. However, it remains unclear whether and how lymphangiogenesis contributes to exercise-induced physiological cardiac growth. We aimed to investigate the role and mechanism of lymphangiogenesis in exercise-induced physiological cardiac growth. MethodsAdult C57BL6/J mice were subjected to 3 weeks of swimming exercise to induce physiological cardiac growth. Oral treatment with vascular endothelial growth factor receptor 3 (VEGFR3) inhibitor SAR131675 was used to investigate whether cardiac lymphangiogenesis was required for exercise-induced physiological cardiac growth by VEGFR3 activation. Furthermore, human dermal lymphatic endothelial cell (LEC)-conditioned medium was collected to culture isolated neonatal rat cardiomyocytes to determine whether and how LECs could influence cardiomyocyte proliferation and hypertrophy. ResultsSwimming exercise induced physiological cardiac growth accompanied by a remarkable increase of cardiac lymphangiogenesis as evidenced by increased density of lymphatic vessel endothelial hyaluronic acid receptor 1–positive lymphatic vessels in the heart and upregulated LYVE-1 and Podoplanin expressions levels. VEGFR3 was upregulated in the exercised heart, while VEGFR3 inhibitor SAR131675 attenuated exercise-induced physiological cardiac growth as evidenced by blunted myocardial hypertrophy and reduced proliferation marker Ki67 in cardiomyocytes, which was correlated with reduced lymphatic vessel density and downregulated LYVE-1 and Podoplanin in the heart upon exercise. Furthermore, LEC-conditioned medium promoted both hypertrophy and proliferation of cardiomyocytes and contained higher levels of insulin-like growth factor-1 and the extracellular protein Reelin, while LEC-conditioned medium from LECs treated with SAR131675 blocked these effects. Functional rescue assays further demonstrated that protein kinase B (AKT) activation, as well as reduced CCAAT enhancer-binding protein beta (C/EBPβ) and increased CBP/p300-interacting transactivators with E (glutamic acid)/D (aspartic acid)–rich-carboxylterminal domain 4 (CITED4), contributed to the promotive effect of LEC-conditioned medium on cardiomyocyte hypertrophy and proliferation. ConclusionOur findings reveal that cardiac lymphangiogenesis is required for exercise-induced physiological cardiac growth by VEGFR3 activation, and they indicate that LEC-conditioned medium promotes both physiological hypertrophy and proliferation of cardiomyocytes through AKT activation and the C/EBPβ-CITED4 axis. These results highlight the essential roles of cardiac lymphangiogenesis in exercise-induced physiological cardiac growth.

Direct Contact with Platelets Induces Podoplanin Expression and Invasion in Human Oral Squamous Cell Carcinoma Cells.

Oral squamous cell carcinoma (OSCC) is mostly diagnosed at an advanced stage, with local and/or distal metastasis. Thus, locoregional and/or local control of the primary tumor is crucial for a better prognosis in patients with OSCC. Platelets have long been considered major players in cancer metastasis. Traditional antiplatelet agents, such as aspirin, are thought to be potential chemotherapeutics, but they need to be used with caution because of the increased bleeding risk. Podoplanin (PDPN)-expressing cancer cells can activate platelets and promote OSCC metastasis. However, the reciprocal effect of platelets on PDPN expression in OSCC has not been investigated. In this study, we found that direct contact with platelets upregulated PDPN and integrin β1 at the protein level and promoted invasiveness of human OSCC Ca9.22 cells that express low levels of PDPN. In another human OSCC HSC3 cell line that express PDPN at an abundant level, silencing of the PDPN gene reduced cell invasiveness. Analysis of the public database further supported the co-expression of PDPN and integrin β1 and their increased expression in metastatic tissues compared to normal and tumor tissues of the oral cavity. Taken together, these data suggest that PDPN is a potential target to regulate platelet-tumor interaction and metastasis for OSCC treatment, which can overcome the limitations of traditional antiplatelet drugs.

The Role of Podoplanin in Skin Diseases.

Podoplanin is a sialomucin-like type I transmembrane receptor glycoprotein that is expressed specifically in lymphatic vessels, sebaceous glands, and hair follicles in normal skin. However, under pathological conditions podoplanin expression is upregulated in various cells, such as keratinocytes, fibroblasts, tumor cells, and inflammatory cells, and plays pivotal roles in different diseases. In psoriasis, podoplanin expression is induced in basal keratinocytes via the JAK-STAT pathway and contributes toward epidermal hyperproliferation. Podoplanin expression on keratinocytes can also promote IL-17 secretion from lymphocytes, promoting chronic inflammation. During wound healing, the podoplanin/CLEC-2 interaction between keratinocytes and platelets regulates re-epithelialization at the wound edge. In skin cancers, podoplanin expresses on tumor cells and promotes their migration and epithelial-mesenchymal transition, thereby accelerating invasion and metastasis. Podoplanin is also expressed in normal peritumoral cells, such as cancer-associated fibroblasts in melanoma and keratinocytes in extramammary Paget’s disease, which promote tumor progression and predict aggressive behavior and poor prognosis. This review provides an overview of our current understanding of the mechanisms via which podoplanin mediates these pathological skin conditions.

Podoplanin expression in salivary gland carcinomas and its clinical significance. An immunohistochemical study.

Podoplanin (D2-40) is alymphatic endothelial marker that is considered as aspecific marker for lymphatic endothelial cells and lymphangiogenesis in salivary gland carcinomas (SGCs). Aim: thepresent study aimed to investigate theimmunohistochemical expression ofpodoplanin in SGCs and to correlate its expression with theclinicopathological parameters and patients' survival. Forty-nine SGC cases were electronically selected. Demographic, clinical, laboratory, and survival data were reviewed and tabulated. Immunohistochemistry was performed using antipodoplanin. Cases were divided into low and high expression based on ascoring system. Ascore of0 and 1 was considered low expression, while > 1 was considered high expression. Podoplanin high expression was seen in 46.9% ofcases, and 53.1% ofcases showed low expression. Significant statistical associations were seen between podoplanin expression and tumour grade ( p ≤ 0.001), tumour-nodal- metastasis (TNM) stage (p ≤ 0.001), tumour size (p ≤ 0.001), nodal metastasis (p ≤ 0.001), tumour type (p = 0.03), prognosis (p ≤ 0.001), and mortality (p ≤ 0.001). The overall survival and progression-free survival differed significantly in cases with high and low expression (p ≤ 0.001). Podoplanin overexpression might be asignificant prognostic indicator for patients with SGCs, implicating that it is apotential therapeutic target to improve survival in these cancer patients.