Podoplanin Expression Research Articles

Surfactant Protein-C Regulates Alveolar Type 2 Epithelial Cell Lineages via the CD74 Receptor.

Deficiency of surfactant protein-C (SPC) increases susceptibility to lung infections and injury, and suppressed expression of SPC has been associated with the severity of acute respiratory distress syndrome (ARDS). Alveolar type 2 epithelial cells (AT2) are critical for maintenance and repair of the lung. However, the role of the SPC in the regulation of AT2 cell lineage and the underlying mechanisms are not completely understood. This study aimed to investigate the mechanisms by which SPC regulates AT2 lineages. Sftpc-/- mice were used to model the SPC deficiency in ARDS patients. We utilized three-dimensional (3D) organoids to compare AT2 lineage characteristics between wild type (WT) and Sftpc-/- mice by analyzing AT2 proliferation, alveolar type 1 cells (AT1) differentiation and CD74 expression, using colony-formation assay, immunofluorescence, flow cytometry, and immunoblots. The results showed that Sftpc-/- mice demonstrated a reduced AT2 cell population. Influenza A virus subtype H1N1 (H1N1) infected Sftpc-/- mice demonstrated reduced AT2 proliferation and AT1 differentiation. Western blot indicated elevated levels of CD74 protein in AT2 cells of Sftpc-/- mice. Colony-forming efficiency was significantly attenuated in AT2 cells isolated from Sftpc-/- mice compared to the WT controls. Podoplanin (PDPN, a marker of AT1 cells) expression and transient cell count significantly increased in Sftpc-/- organoids. Moreover, siRNA-mediated gene silencing of CD74 in AT2 cells significantly increased AT2 proliferation and AT1 differentiation in Sftpc-/- organoids. This study suggests that SPC regulates AT2 lineage in vitro and in vivo. The SPC might influence AT2 lineage during the lung epithelium repair by activating signaling mechanism involving CD74 receptor.

Functional analysis of fibroblasts and macrophages in head and neck paragangliomas.

Head and neck paragangliomas (HNPGN) are tumours that carry significant morbidity The role of the stroma in the pathogenesis of HNPGN is not completely understood. This study explores the profile of fibroblasts and macrophages in HNPGN. Ten patients undergoing HNPGN surgery were recruited. CD68 and CD163 immunohistochemistry was performed for macrophage analysis; CD90 and podoplanin (PDPN) expression was examined to identify fibroblasts. RT-qPCR was performed on HNPGN tissue for macrophage- and fibroblast-associated molecules. Fibroblast cultures were established from HNPGN were analysed by RT-qPCR and flowcytometry. Confocal microscopy for MCT1 and MCT4 was performed in HNPGN. CD68 and CD163 expressing macrophages were noted in HNPGN. CD90 and PDPN expressing cells were present in HNPGN. RT-qPCR analysis showed expression of phenotypic and functional macrophage- and fibroblast-associated molecules in HNPGN. RT-qPCR analysis of fibroblasts cultured from HNPGN confirmed the expression of several molecules including PDPN at comparable levels to healthy tissue fibroblasts. Expression of FAP, MCT-1, insulin receptor (CD220) and insulin growth factor receptor-2 (CD222) was noted on HNPGN derived fibroblasts on flowcytometry. MCT1 and MCT4 were expressed in HNPGN tumour cells and stromal macrophages in-situ. Fibroblasts and macrophages are present in the HNPGN tumour microenvironment, and several macrophage and fibroblast functional markers are expressed in HNPGN. Macrophages in HNPGN tissue express metabolic markers MCT1 and MCT4. Further analysis of the fibroblast and macrophage function in HNPGN will improve our understanding of their potential roles in tumour pathogenesis.

The prognostic implications of podoplanin in cancer-associated fibroblasts and PD-L1 expression in high-grade neuroendocrine carcinoma of the lung.

Podoplanin (PDPN) expression in cancer-associated fibroblasts (CAFs) (CAF-PDPN) is considered a poor prognostic factor in nonsmall cell lung cancer, but little is known about its clinical significance in high-grade neuroendocrine carcinoma of the lung (HGNEC). This study examines the association between CAF-PDPN and stromal programmed death-ligand 1 (PD-L1) expression and the prognostic implications of CAF-PDPN and PD-L1 expression status in surgically resected HGNEC patients. Immunohistochemical analyses were performed on 121 resected HGNEC specimens using antibodies against PDPN and PD-L1. Correlations between CAF-PDPN, stromal PD-L1 expression, and clinicopathologic features and their implications for survival were analyzed statistically. There were substantially more large-cell neuroendocrine carcinomas in the stromal PD-L1-positive group and more vascular invasion in the tumoral PD-L1-positive group. PDPN expression in CAF was moderately correlated with stromal PD-L1 expression (ρ = 0.567, p < 0.001). In a survival analysis combining CAF-PDPN and stromal PD-L1 status, the 5-year RFS rates for Group A: CAF-PDPN (+)/stromal PD-L1 (+), Group B: CAF-PDPN (+)/stromal PD-L1 (-), Group C: CAF-PDPN (-)/stromal PD-L1 (+), and Group D: CAF-PDPN (-)/stromal PD-L1 (-) were 62.0%, 46.8%, 17.5%, and 20.2%, respectively, with corresponding 5-year OS rates of 76.6%, 69.2%, 27.0%, and 25.3%. The log-rank test showed statistically significant differences among the groups in RFS (p < 0.001) and OS (p < 0.001). There is a correlation between CAF-PDPN and tumoral/stromal PD-L1 expression, and positive status for either CAF-PDPN or stromal PD-L1 expression could be an independent favorable prognostic factor in surgically resected HGNEC patients.

Podoplanin expression in various types of oral dysplasia and oral squamous cell carcinoma

ObjectiveThis study was aimed at investigating the roles of podoplanin (PDPN) as a marker associated with malignant development, progression, and poor prognosis in oral leukoplakia and various forms of oral squamous cell carcinoma (OSCC), particularly in relation to the extent of invasion. MethodsImmunohistochemical analysis of PDPN was conducted on 77 histologically confirmed, formalin-fixed, paraffin-embedded samples representing various degrees of OSCC invasion and dysplasia grades. ResultsThe samples were analyzed with Fisher's exact test and the Kruskal–Wallis test. Significant associations between sample type and the intensity, percentage, distribution, location, inflammation, and lymphatic vessel involvement according to staining were observed (p < 0.05). The PDPN staining score progressively increased from mild dysplasia to carcinoma in situ within the dysplasia classification, whereas in the OSCC classification, the highest overexpression was observed in the well-differentiated group. ConclusionEarly invasive OSCC exhibited more aggressive behavior than micro-invasive OSCC, although both were less aggressive than invasive OSCC. These findings may aid in improving prognostic accuracy and informing treatment strategies.

Podoplanin Expression in Early-Stage Colorectal Cancer-Associated Fibroblasts and Its Utility as a Diagnostic Marker for Colorectal Lesions.

(Background) Cancer-associated fibroblasts (CAFs) are major cancer stromal components. CAFs have diverse functions and cell origins. Podoplanin (PDPN), a lymphatic vessel marker, is also a CAF marker in certain cancers. On daily diagnosis of early colorectal carcinoma (CRC), PDPN upregulation in the stroma is often encountered, suggesting PDPN-positive CAFs have emerged. However, PDPN-positive CAFs in early CRC have not been studied well. (Methods) On immunohistochemistry, PDPN expression in the lamina propria or stroma of adenomas, early CRCs, and neuroendocrine tumors, their normal neighbors, and non-neoplastic colorectal lesions were compared. Single-cell RNA sequencing (scRNA-seq) of CRC was used to explore PDPNhigh CAFs' cell origins. (Results) Reticular cells or pericryptal fibroblasts in the lamina propria of adenomas and early CRCs showed higher PDPN expression than did normal mucosae and non-neoplastic lesions (p < 0.01). Pericryptal PDPN expression was a diagnostic feature of adenomas and early CRCs. scRNA-seq of CRCs highlighted that PDPNhigh CAFs had distinctly higher COL4A1, COL4A2, and WNT5A expression, unlike well-known CAFs characterized by high FAP, POSTN, or ACTA2 expression. (Conclusions) We demonstrated that pericryptal fibroblasts and reticular cells in the lamina propria are origins of early-stage CRC CAFs and thus have potential as a diagnostic marker for distinguishing colorectal non-neoplastic from neoplastic lesions.

Differential Impact of Tumor Endothelial Angiopoietin-2 and Podoplanin in Lymphatic Endothelial Cells on HCC Outcomes with Tyrosine Kinase Inhibitor Treatment According to Sex.

Hepatocellular carcinoma (HCC) is the second leading cause of cancer death worldwide. Curative treatments are available to a minority of patients, as HCC is often diagnosed at an advanced stage. For patients with unresectable and multifocal HCC, tyrosine kinase inhibitor drugs (TKIs) are the only potential treatment option. Despite extensive research, predictors of response to these therapies remain elusive. This study aimed to analyze the biological and histopathological characteristics of HCC patients treated with TKIs, focusing on angiogenesis and lymphangiogenesis. Immunohistochemistry quantified the expression of angiopoietin-2 (Ang2), lymphatic endothelial cells (LEC) podoplanin, and C-type Lectin Domain Family 2 (CLEC-2), key factors in neoangiogenesis and lymphangiogenesis. An increased expression of endothelial Ang2 and LEC podoplanin predicted a lower risk of metastasis. Female patients had significantly longer overall survival and survival on TKIs, associated with higher tumor expression of endothelial Ang2 and LEC podoplanin. Moreover, LEC podoplanin expression and a longer time on TKIs were independently correlated with improved survival on TKI therapy at Cox regression analysis. These findings suggest that endothelial Ang2 and LEC podoplanin could be potential biomarkers for predicting treatment outcomes and guiding therapeutic strategies in HCC patients treated with TKIs.

Dipeptidyl peptidase 4-positive cancer-associated fibroblasts enhance lung adenocarcinoma growth

Cancer-associated fibroblasts (CAFs) are a heterogeneous population of fibroblasts with various features in the cancer stroma and have been reported to influence cancer progression through cell–cell interactions in various types of malignancies, including lung adenocarcinoma (LUAD). Dipeptidyl peptidase 4 (DPP4) is a transmembrane protein with serine protease activity and is involved in the progression of tumors, metabolic diseases, and autoimmune diseases. In the present study, we focused on the role of DPP4-positive CAFs in LUAD. Immunohistochemistry revealed that 38 of 89 LUAD patients showed DPP4 expression in the fibrous stroma, and patients harboring DPP4-positive CAFs were more often male, had a higher Brinkman index, and had a higher Ki-67 labeling index of tumor cells than those with DPP4-negative CAFs. DPP4-positivity was associated with the expression of other CAF markers, α-SMA, periostin, and podoplanin, as well as a cellular senescence marker, p16. In the in vitro study, conditioned media collected from pulmonary fibroblast (OUS-11, HPF, and HPF-C)-induced overexpression of DPP4 significantly promoted the proliferation of LUAD cells (A549 and PC-9) and increased the expression levels of MCP-1, IL-8, IL-6, and GCSF in the media compared to those in controls. In addition, OUS-11 overexpression in DPP4 overexpression increased periostin expression. In conclusion, DPP4-positive CAFs could promote lung adenocarcinoma cell growth by producing soluble factors, and DPP4 inhibition may inhibit cancer progression.

Lymphangiogenesis in Odontogenic Keratocysts Compared with Dentigerous Cysts.

Podoplanin can indicate the lymphangiogenesis. On the other hand, lymphangiogenesis affects the biological behavior of lesions. The clinical behavior of odontogenic keratocysts (OKC) and dentigerous cysts (DC) is different. This study aimed to evaluate the immunohistochemical expression of podoplanin and to investigate lymphangiogenesis in OKCs as compared to DCs. In this experimental laboratory study, sixty paraffined blocks, including 30 OKC and 30 DC samples, were examined in this study, all of which were histopathologically non-inflamed. To evaluate lymphangiogenesis, the immunohistochemical reaction of D2-40 was evaluated via cytoplasmic and membrane staining of lymphatic endothelial cells. The expression of podoplanin in the epithelial cells of two cyst groups was also examined. To analyze the collected data and compare the results between the two groups of cysts, independent samples t-test, Mann-Whitney U test, and Chi-square test were performed in SPSS version 22. The significance level was set at 0.05. The mean lymph node count and podoplanin expression were significantly higher in the OKC epithelium as compared to DC (p< 0.001). Based on the results, 90% of OKC samples and 43.3% of DC samples showed grade 3 staining. The rate of lymphangiogenesis and podoplanin expression in the epithelium were higher in OKCs compared to DCs. According to the results, the expression of podoplanin may be a useful marker for determining the invasiveness and proliferation of OKC.

Combining RNAscope, Immunohistochemistry (IHC) and Digital Image Analysis to Assess Podoplanin (PDPN) Protein and PDPN_mRNA Expression on Formalin-Fixed Paraffin-Embedded Normal Human Placenta Tissues.

The expression and function of podoplanin (PDPN) in the normal human placenta has been debated in placental evaluation. This study emphasizes the importance of a multimodal approach of PDPN expression in normal human placentas. A complete examination is performed using immunohistochemistry, RNAscope and automated Digital Image examination (DIA) interpretation. QuPath DIA-based analysis automatically generated the stromal and histological scores of PDPN expression for immunohistochemistry and RNAscope stains. The umbilical cord's isolated fibroblasts and luminal structures expressed PDPN protein and PDPN_mRNA. RNAscope detected PDPN_mRNA upregulation in syncytial placental knots trophoblastic cells, but immunohistochemistry did not certify this at the protein level. The study found a significant correlation between the IHC and RNAscope H-Score (p = 0.033) and Allred Score (p = 0.05). A successful multimodal strategy for PDPN assessment in human placentas confirmed PDPN expression heterogeneity in the full-term human normal placenta and umbilical cord at the protein and mRNA level. In placental syncytial knots trophoblastic cells, PDPN showed mRNA overexpression, suggesting a potential role in placenta maturation.

Association of podoplanin expression to histopathological grades of oral epithelial dysplasia and oral squamous cell carcinoma.

To determine the expression of podoplanin, and to correlate it with histopathological grades in oral epithelial dysplasia and oral squamous cell carcinoma cases. The retrospective, analytical, cross-sectional study was conducted at the City Laboratory, Peshawar, Pakistan, and comprised specimen block data of histologically diagnosed cases of oral benign lesions, dysplastic lesions and oral squamous cell carcinoma from January 2017 to August 2021. Two sections (4um) were cut from each specimen block for Haematoxylin and Eosin staining and immunohistochemistry. The slides were re-evaluated by two pathologists for confirmation of the diagnosis, and podoplanin marker was applied to cases selected using immunohistochemistry. Data was analysed using SPSS 22. Of the 80 cases identified, 68(85%) were analysed. There were 20(29.4%) benign cases; 11(55%) females and 9(45%) males with mean age 39.90±16.23 years, 20(29.4%) oral dysplastic cases; 14(70%) males and 6(30%) females with mean age 57.75±12.02 years, and 28(41.2%) oral squamous cell carcinoma cases; 17(61%) males and 11(39%) females with mean age 50.55±14.80 years. Podoplanin expression in oral epithelial dysplasia cases was significant (p=0.028), while it was not significant in the other 2 groups (p>0.05). Podoplanin when used along with histopathological evaluation could aid as an adjuvant technique in the diagnosis and grading of oral epithelial dysplasia.

Abstract LB156: Targeting epigenetic activity of beta-catenin/CBP impedes oral cancer progression

Abstract Head and neck cancer is a complex malignancy with its major anatomical subsite, cancer of the oral cavity, ranking among the most deadly and disfiguring cancers. Oral cancer presents primarily as HPV-negative oral squamous cell carcinoma (OSCC) whose etiology is associated with tobacco and alcohol use and for which there are limited treatments. Whereas immunotherapies, such as anti-PD-1 antibodies, have become a promising therapeutic option, only ~20% of head neck cancer patients benefit from anti-PD-1 immunotherapy. We and others have shown that non-mutational epigenetic reprogramming mediated by the β-catenin/CBP complex promotes aggressive cell phenotypes in OSCC by establishing open chromatin at the transcription start sites of genes associated with cancer stemness. Accordingly, pharmacological inhibition of this complex dramatically inhibits OSCC evolution in a syngeneic mouse model of OSCC. Here, we evaluated whether the inhibition of β-catenin/CBP epigenetic activity would enhance the effects of anti-PD-1 immunotherapy. We adapted a syngeneic mouse model of tobacco-associated oral carcinogenesis that utilizes a mouse cell line, 4MOSC1, derived from 4-nitroquinoline-1 oxide- (4NQO)-induced tongue tumors of C57BL/6J mice. After tumors developed for 7 days, mice were blindly separated into treatment cohorts (n=13, each) to receive vehicle control (PBS), monotherapy (either 10 mg/kg anti-PD-1 EOD IP, or 100 mg/kg E7386, a Wnt signaling pathway modulator, QD oral gavage) or combination therapy (anti-PD-1 + E7386). Tumor isografts were harvested 11 days post initiation of treatments and processed for histopathology, immunohistochemistry, and immunofluorescence analyses. Measurements of tumor volumes showed that combination therapy resulted in a statistically significant reduction by ~80% compared to control mice and that it surpassed tumor decrease by either monotherapy. These results were confirmed by histopathology analyses. Evaluation of tumor tissues by immunofluorescence revealed statistically significant decreases in Cbp, H3K4me3, Keratin 14, and Podoplanin expression in response to E7386 alone and in combination with anti PD-1. Collectively our results suggest that a combination therapy comprising anti PD-1 treatment with E7386-targeting β-catenin/CBP epigenetic signaling is likely to impede OSCC evolution to advanced disease. Supported by Eisai, Co Ltd Research Award (MAK), NIH 5R01 DE030350 (MAK, SM, XV) and 5R01 DE031413 (MVB). Citation Format: Emily Fisher, Anthony Spinella, Junji Matsui, Kenichi Nomoto, Xaralabos Varelas, Manish Bais, Maria Kukuruzinska. Targeting epigenetic activity of beta-catenin/CBP impedes oral cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB156.

Serum podoplanin expression and frequency of thrombosis in adult de novo acute myeloid leukemia patients: An Egyptian single center study

Background Cancer-associated thrombosis although represents a significant disease worse prognosis, understanding its underlying pathophysiology remains obscure. Podoplanin and its platelet ligand C-type lectin receptor type-2 have been investigated in the past few years for their potential role as procoagulant substances as it has been shown in many studies that binding of podoplanin with platelet C-type lectin receptor type-2 results in enhancement of platelet aggregation and thrombotic insults. Aim In this study, serum podoplanin was measured in newly diagnosed acute myeloid leukemia (AML) patients and its relation to the incidence of thrombosis in these patients in addition to its relation to other clinical, laboratory, and prognostic outcomes. Patients and methods This study included 80 participants (60 newly diagnosed adult AML patients and 20 age-matched and sex-matched healthy controls). Blood counts and flow cytometry using an acute leukemia panel were performed in addition to serum podoplanin, and cytogenetic studies including conventional karyotyping and fluorescence in-situ hybridization were performed to determine the risk group. The clinical status of the patients, particularly the incidence of thrombotic events in the following 6 months, as well as the D28 outcome and 6-month survival, were determined and reported. Results Serum podoplanin was highly expressed in AML patients compared with control samples, with a highly significant difference (P=0.001). There was a significant inverse relation between serum podoplanin level, hemoglobin level, and white blood cell count (P=0.006 and 0.036, respectively). Those with thrombotic events during the course of the disease did not show statistically significant results when compared with the control group with regard to serum podoplanin levels (P=0.546). Conclusion Serum podoplanin was much higher in AML patients than in the control group (P=0.000), and it was inversely related to platelet level (P=0.036) and total leukocyte count (P=0.006). However, there was no statistically significant link between podoplanin level and the incidence of thrombotic events (P=0.546).

Prognostic significance of tumor budding in patients with pancreatic invasive ductal carcinoma who received neoadjuvant therapy

Neoadjuvant therapy is commonly used for invasive pancreatic ductal carcinoma (PDAC). Tumor budding and high podoplanin expression in cancer-associated fibroblasts (CAFs) are prognostic factors in patients with various carcinomas including PDAC who have not received neoadjuvant therapy. In this study, we investigated whether tumor budding and podoplanin-positive CAFs are associated with outcomes in Japanese PDAC patients with neoadjuvant therapy. Histopathological findings of surgically resected PDACs with neoadjuvant therapy from 2005 to 2018 were reviewed (n = 97). With reference to International Tumor Budding Consensus Conference recommendations, tumors were evaluated for budding at 20 × magnification (/0.785 mm2) and at 40 × magnification (/0.237 mm2; mean number of fields: 3) for podoplanin expression in CAFs (%). Overall survival, disease-free survival, and disease-specific survival (DSS) were analyzed using the log-rank test and Cox proportional hazards model. After adjusting for T category, N category, resection margin, and adjuvant therapy, multivariate analyses demonstrated that tumor budding at 40 × magnification was an independent prognostic factor for worse DSS (hazard ratio: 2.41, p = 0.022). Tumor budding at 20 × magnification and podoplanin-positive CAFs tended to be associated with worse DSS; however, these findings were not statistically significant. Our findings indicate that tumor budding is an independent prognostic factor in PDAC patients with neoadjuvant therapy.

10091-COT-12 ELUCIDATING THE PATHOPHYSIOLOGY OF POST-OPERATIVE VENOUS THROMBOEMBOLISM IN IDH-WILDTYPE MALIGNANT GLIOMAS

Abstract BACKGROUND We have previously reported elevated expression of podoplanin and high incidence of post-operative venous thromboembolism (VTE) in IDH-wildtype gliomas (Watanabe et al., World Neurosurgery, 2019). Podoplanin binds to C-type lectin-like receptor-2 (CLEC-2) on the surface of platelets and induces platelet aggregation, potentially leading to the development of VTE. In the present report, we monitor serum podoplanin and CLEC-2 after surgery in malignant glioma patients to directly determine if this is the cause of post-operative VTE. METHODS Fourty-four malignant glioma patients undergoing surgery at the Department of Neurosurgery, Niigata University Hospital between April, 2018 and August, 2020 were assessed. Platelet counts as well as serum D-dimer, podoplanin, soluble CLEC-2, and C2PAC index (soluble CLEC-2 divided by platelet count) were measured within 10 days after surgery. Serum podoplanin and soluble CLEC-2 were assessed by enzyme-linked immunosorbent assay (ELISA). Values for IDH-wildtype glioma patients and IDH-mutant glioma patients were compared to patients undergoing microvascular decompression (MVD) and healthy volunteers (HV). RESULTS Post-operative VTE was observed in 8 out of 35 (23%) IDH-wildtype glioma patients, compared to 1 out of 9 (11%) IDH-mutant glioma patients. Serum soluble CLEC-2 levels (p = 0.0004) and C2PAC index (p = 0.0002) were significantly elevated in IDH-wildtype glioma patients compared to IDH-mutant glioma, MVD and HV groups. A C2PAC index threshold of 3.7 provide an 87.5% sensitivity and 51.9% specificity to predict post-operative VTE in IDH-wildtype gliomas. We serially monitored podoplanin and soluble CLEC-2 in select patients, and found that podoplanin is transiently elevated, followed by soluble CLEC-2 after surgery. CONCLUSION Platelet aggregation due to the activation of podoplanin-CLEC2 axis leads to post-operative VTE in IDH-wildtype malignant glioma patients. The C2PAC index is a potential biomarker for the early detection of VTE after surgery in these patients.

Podoplanin Expression Measured By Flow Cytometry Accurately Identifies Patients with Acute Promyelocytic Leukemia at Diagnosis

Acute promyelocytic leukemia (APL) is a hematological emergency associated with high early mortality rates, thus requiring prompt diagnosis and treatment initiation. Currently, diagnostic suspicion relies on morphological criteria, which can be further corroborated by immunophenotypic analyses, until results based on molecular techniques confirm the diagnosis. However, while both cytology and immunophenotypic analyses are very important in this setting, their accuracy can be influenced by inherent morphological variation of blasts, as well as by gating and other technical issues related to flow cytometry. In this context, novel parameters that could contribute to the segregation of APL from other forms of acute myeloid leukemia (AML) would be desirable. Recently, Lavallée et al demonstrated that the aberrant expression of podoplanin (PDPN), a protein that mediates platelet activation in inflammatory contexts, by leukemic cells is as a relevant mediator of the coagulopathy of APL, as well potential biomarker of this condition based on the analysis of primary cells from patients with AML. The aim of this study was to prospectively and independently validate whether the surface expression of PDPN by leukemic promyelocytes measured by flow cytometry can contribute to the differential diagnosis between APL and other forms of AML. We also explored the association of PDPN expression with clinical and laboratory characteristics of these patients. The study population consisted of all consecutive patients diagnosed with APL by cytological, immunophenotypical and molecular techniques in our adult academic hematology hospital from 2020 to 2023. Exclusion criteria included the presence of hemodynamic instability or refusal to participate. The expression of PDPN was measured by flow cytometry using BD FACSCanto II™ cytometer. Analysis was performed in accordance with EuroFlow protocols, with a panel that includes CD45, CD33, CD34, MPO, CD117, CD13, HLA-DR, as well as an antibody against PDPN (PE anti-human Podoplanin Antibody - Catalog# 337004 - BioLegend). Lymphocytes were used as internal negative control for PDPN expression. Data were analyzed with Infinicyt™ software and reported both as the % of PDPN + cells or according to mean fluorescence intensity (MFI). Patients with other forms of AML diagnosed during the same period and matched for age, gender and peripheral blast count were used to compare the diagnostic accuracy of PDPN measurement. Clinical and laboratory data were obtained from the medical records. The study was approved by the Institutional Review Board and all participants provided written informed consent. In total, 19 consecutive patients with confirmed diagnosis of APL were compared with 18 patients with non-APL AML. Clinical and laboratory data from the study population are shown in table 1. The expression of PDPN in leukemic blasts was significantly higher in APL compared to non-APL AML, considering either the percentage of PDPN + cells or the MFI (table 1; figure 1a-b). When considered as a categorical variable, the expression of PDPN was strongly associated with the diagnosis of APL (Chi-square test= 19.169; P&amp;lt;0.001). PDPN expression was inversely correlated with platelet count (R S= -0.47; P=0.003) and fibrinogen (R S= -0.51; P=0.001), but not with other laboratory parameters such as PT and aPTT. No association of PDPN expression with the available clinical variables was observed, although it should be noted that our study is underpowered to confirm these findings. We next estimated the diagnostic accuracy of PDPN expression by flow cytometry by ROC analysis. As shown in figures 1c-d, the area under the ROC curve was higher than 0.9 for both analytical strategies. In conclusion, our prospective study demonstrated that measurement of the expression of PDPN by flow cytometry at diagnosis is capable to accurately segregate APL from other forms of AML. Additional studies are warranted to explore the clinical association of PDPN expression in larger and independent cohorts.

The role of podoplanin in tumor-associated thrombosis

Venous thromboembolism (VTE) is highly consequential for patients with cancer, it is the second leading cause of death in these patients. The literature describes several mechanisms leading to these complications. One of these is the interaction of podoplanin (PDPN), which is the subject of this article, with its receptor on platelets CLEC-2 (C-type lectin-like type II transmembrane receptor). This interaction leads to platelet activation and promotes hematogenous metastasis and thrombosis associated with cancer. Podoplanin is expressed in gliomas, squamous cell carcinoma, osteosarcoma by cancer cells, and it is also normally expressed in podocytes and lymphatic endothelial cells, but not in vascular endothelium. Thrombus inflammation initiates ectopic expression of podoplanin in vascular endothelial cells, which promotes thrombosis. It has been shown that podoplanin expression correlates with the incidence of VTE, as well as with cancer metastasis. Violation of the PDPN-CLEC-2 interaction may become a new direction in the development of drugs for the prevention of thrombosis for patients with cancer.

Fibroblasts Derived From Vestibular Schwannoma Express Protumorogenic Markers.

Vestibular schwannomas (VSs), despite being histologically benign, cause significant morbidity because of their challenging intracranial location and the propensity for growth. The role of the stroma and particularly fibroblasts, in the progression of VS, is not completely understood. This study examines the profile of fibroblasts in VS. Seventeen patients undergoing surgical excision of VS were recruited into the study. Reverse transcription with quantitative polymerase chain reaction (RT-qPCR) was performed on VS tissue samples and fibroblast-associated molecules examined. Immunofluorescence and immunohistochemistry in VS tissue were used to study the expression of fibroblast markers CD90 and podoplanin in situ. Fibroblast cultures were established from VS, and RT-qPCR analysis was performed on a panel of fibroblast markers on VS and control tissue fibroblasts. Several fibroblast-associated molecules including members of galectin family and matrix metalloproteinases were found to be expressed in VS tissue on RT-qPCR analysis. In situ, expression of CD90 and podoplanin was observed in VS tissue both on immunohistochemistry and immunofluorescence. RT-qPCR analysis of fibroblasts from VS and control vestibular neuroepithelium (NE) showed a higher expression of several molecules of the galectin and matrix metalloproteinases family on VS fibroblasts compared with NE fibroblasts. This work examines fibroblasts from VS and shows qualitative differences from NE fibroblasts on RT-qPCR. Further understanding of the fibroblast function in the progression of VS will potentially unveil new targets to manage VS growth.

Pre-operative incisional biopsy of oral squamous cell carcinoma: high podoplanin expression is related to perineural invasion and may be a useful predictor of disease progression

Immunohistochemical analysis of podoplanin expression as a pre-operative molecular marker for perineural invasion (PNI) may represent an attractive strategy for surgical management of oral squamous cell cancer (OSCC). We evaluated the relationship between podoplanin expression and PNI in pre-operative incisional biopsies of OSCC. After performing pathological staging and histologic and immunohistochemical evaluation of 83 surgical specimens, we performed multivariable logistic regression analysis to examine the relationship between PNI and independent variables. To evaluate the utility of podoplanin immunopositivity for discrimination of PNI status pre-operatively, we calculated the sensitivity, specificity, positive predictive value, and negative predictive value. We performed receiver operating characteristic curve analysis to evaluate the diagnostic accuracy of podoplanin immunopositivity for predicting PNI alone and in combination with age, T stage, N stage, and index site. We observed podoplanin expression in 42 (50.6%) of all the 83 pre-operative incisional biopsies and 29 of the pre-operative biopsies of the 31 (93.5%) postoperative specimens with PNI. The rate of podoplanin expression was significantly higher in patients with pT3 to pT4 stage and pN+ stage disease. Podoplanin positivity in the pre-operative biopsy showed high sensitivity in predicting PNI in the surgical specimen. Podoplanin expression appears to be an independent pre-operative variable significantly related to PNI and a possibly valuable prognostic marker for therapeutical planning and surgical treatment of OSCC.

Reduction in disialyl-T antigen levels in mice deficient for both St6galnac3 and St6galnac4 results in blood filling of lymph nodes

Sialic acid (SA) is present at the terminal ends of carbohydrate chains in glycoproteins and glycolipids and is involved in various biological phenomena. The biological function of the disialyl-T (SAα2-3Galβ1-3(SAα2-6)GalNAcα1-O-Ser/Thr) structure is largely unknown. To elucidate the role of disialyl-T structure and determine the key enzyme from the N-acetylgalactosaminide α2,6-sialyltransferase (St6galnac) family involved in its in vivo synthesis, we generated St6galnac3- and St6galnac4-deficient mice. Both single-knockout mice developed normally without any prominent phenotypic abnormalities. However, the St6galnac3::St6galnact4 double knockout (DKO) mice showed spontaneous hemorrhage of the lymph nodes (LN). To identify the cause of bleeding in the LN, we examined podoplanin, which modifies the disialyl-T structures. The protein expression of podoplanin in the LN of DKO mice was similar to that in wild-type mice. However, the reactivity of MALII lectin, which recognizes disialyl-T, in podoplanin immunoprecipitated from DKO LN was completely abolished. Moreover, the expression of vascular endothelial cadherin was reduced on the cell surface of high endothelial venule (HEV) in the LN, suggesting that hemorrhage was caused by the structural disruption of HEV. These results suggest that podoplanin possesses disialyl-T structure in mice LN and that both St6galnac3 and St6galnac4 are required for disialyl-T synthesis.

Expression Profile of Microenvironmental Factors in the Interface Zone of Colorectal Cancer: Histological-Stromal Biomarkers and Cancer Cell-Cancer-Associated Fibroblast-Related Proteins Combined for the Assessment of Tumor Progression

Introduction: The characterization of tumor microenvironment (TME) related factors and their impact on tumor progression have attracted much interest. We investigated cancer cells and cancer-associated fibroblasts (CAFs) to evaluate biomarkers that are associated with neoplastic progression, observing them in different interface zones of colorectal cancer. Methods: On 357 CRC tissue microarrays, using immunohistochemistry, we examined the associations of podoplanin and α-SMA expressed in cancer cells and CAFs and evaluated them in different areas: tumor core, invasive front, tumor budding, tumor-stroma ratio (TSR) scoring, and desmoplastic stroma. Results: CAFs expressing α-SMA were found in more than 90% of the cases. Podoplanin+ was detected in cancer cells and CAFs, with positivities of 38.6% and 70%, respectively. Higher α-SMA+ CAFs and podoplanin+ cancer cells were observed predominantly at the TSR score area: 94.3% and 64.3% of cases, respectively. The status of podoplanin in CAFs+ was higher in the desmoplastic area (71.6%). Stroma-high tumors showed increased expression of α-SMA and podoplanin in comparison with stroma-low tumors. The status of podoplanin in cancer cells was observed in association with lymphatic invasion and distant metastasis. Conclusion: The substance of the CRC was composed predominantly of the surrounding stroma-α-SMA+ CAFs. Podoplanin expressed in the prognosticator zones was associated with unfavorable pathological features. The combination of histologic and protein-related biomarkers can result in a tool for the stratification of patients with CRC.