Value of podoplanin as an immunohistochemical marker in tumor diagnosis: a review and update

Periarterial or perivenous invasion is an independent indicator of lymph node metastasis in invasive breast carcinoma of no special type

Pathological diagnosis of breast cancer often includes cases of lymph node metastases without lymphatic or lymphovascular invasion by the primary tumor. In this study, to resolve this discrepancy, we designed a sensitive method to detect lymphatic invasion and correlate it with lymph node metastasis. Elastica van Gieson (EVG) staining and D2-40 immunohistochemistry revealed the abundant distribution of lymphatic vessels around blood vessels in the mammary tissue in close proximity to the elastic fibers around the arteries and veins. Based on the histological location of the blood and lymphatic vessels, we hypothesized that, in breast cancer, perivascular invasion is similar to lymphatic invasion and correlates with the presence of lymph node metastasis. Using EVG staining, perivascular invasion was histologically classified into periarterial invasion (periA), perivenous invasion (periV), and periarterial or perivenous invasion (periA/V). We tested our method and compared it to other methods commonly used for identifying lymphatic invasion in 105 patients with invasive breast carcinoma of no special type (IBC-NST) who received minimal preoperative therapy. The correlation between perivascular invasion and lymph node metastasis in these patients was statistically analyzed, including findings related to lymphatic invasion, such as retractile artifacts and perineural invasion. PeriA, periV, and periA/V showed significant correlations with lymph node metastasis. PeriA/V had high sensitivity and negative predictive value. The odds ratio (OR) for periV was significantly high in the univariate analysis, while the ORs for periA/V, retraction artifacts, and perineural invasion were significantly high in both the univariate and multivariate analyses. In particular, periA/V revealed a strong correlation with lymph node metastasis (OR: 61.8). These findings indicate that the IBC-NST periA/V ratio is a sensitive pointer of lymphatic invasion and could be an independent and reliable indicator of lymph node metastasis.

Mechanisms of platelet activation in cancer-associated thrombosis: a focus on myeloproliferative neoplasms

Platelets are anucleate blood cells that play key roles in thrombosis and hemostasis. Platelets are also effector cells in malignancy and are known to home into the microenvironment of cancers. As such, these cells provide central links between the hemostatic system, inflammation and cancer progression. Activation of platelets by cancers has been postulated to contribute to metastasis and progression of local tumor invasion. Similarly, cancer-activated platelets can increase the risk of development of both arterial and venous thrombosis; a major contributor to cancer-associated morbidity. Platelet granules secretion within the tumor environment or the plasma provide a rich source of potential biomarkers for prediction of thrombotic risk or tumor progression. In the case of myeloproliferative neoplasms (MPNs), which are characterized by clonal expansion of myeloid precursors and abnormal function and number of erythrocytes, leukocytes and platelets, patients suffer from thrombotic and hemorrhagic complications. The mechanisms driving this are likely multifactorial but remain poorly understood. Several mouse models developed to recapitulate MPN phenotype with one of the driving mutations, in JAK2 (JAK2V617F) or in calreticulin (CALR) or myeloproliferative leukemia virus oncogene receptor (MPL), have been studied for their thrombotic phenotype. Variability and discrepancies were identified within different disease models of MPN, emphasizing the complexity of increased risk of clotting and bleeding in these pathologies. Here, we review recent literature on the role of platelets in cancer-associated arterial and venous thrombosis and use MPN as case study to illustrate recent advances in experimental models of thrombosis in a malignant phenotype. We address major mechanisms of tumor-platelet communication leading to thrombosis and focus on the role of altered platelets in promoting thrombosis in MPN experimental models and patients with MPN. Recent identification of platelet-derived biomarkers of MPN-associated thrombosis is also reviewed, with potential therapeutic implications.

Giant cavernous malformation of the posterior fossa with lymphangiomatous phenotype, associated with orbital venolymphatic anomaly in an 11-month-old patient: case report and literature review

The synchronous presentation of venolymphatic anomalies of the orbit and noncontiguous intracranial cavernous malformations is uncommon. Herein, we present a case of an 11-month-old female patient diagnosed with orbital venolymphatic anomaly associated with a large cavernous malformation in the posterior fossa, who underwent complete surgical resection of the latter. The immunohistochemical analysis was positive for podoplanin, a marker expressed by lymphatic endothelial cells, but not vascular endothelium. This exceptional finding suggests lymphatic involvement in the etiology of the lesion. In our review of the literature, we did not find similar cases in patients under 1 year of age.

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 <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.

Expression of podoplanin in various types of feline tumor tissues

Podoplanin is expressed in various human tumors where it promotes tumor progression, epithelial-mesenchymal transition, and distant metastasis. Podoplanin is also expressed in cancer-associated fibroblasts and induces tumor malignancy. The objective of this study was to evaluate podoplanin expression in various types of feline tumor tissues. Immunohistochemical analysis revealed that podoplanin was expressed in cells of 13/15 (87%) squamous cell carcinomas and 5/19 (26%) fibrosarcomas. Moreover, cancer-associated fibroblasts expressed podoplanin in most tumor types, including 18/21 (86%) mammary adenocarcinoma tissues. Our findings demonstrate that various types of feline tumor tissues expressed podoplanin, indicating the importance of the comparative aspects of podoplanin expression, which may be used as a novel research model for podoplanin biology.

Podoplanin is indispensable for cell motility and platelet-induced epithelial-to-mesenchymal transition-related gene expression in esophagus squamous carcinoma TE11A cells

Background

The transmembrane glycoprotein podoplanin (PDPN) is upregulated in some tumors and has gained attention as a malignant tumor biomarker. PDPN molecules have platelet aggregation-stimulating domains and, are therefore, suggested to play a role in tumor-induced platelet activation, which in turn triggers epithelial-to-mesenchymal transition (EMT) and enhances the invasive and metastatic activities of tumor cells. In addition, as forced PDPN expression itself can alter the propensity of certain tumor cells in favor of EMT and enhance their invasive ability, it is also considered to be involved in the cell signaling system. Nevertheless, underlying mechanisms of PDPN in tumor cell invasive ability as well as EMT induction, especially by platelets, are still not fully understood.

Methods

Subclonal TE11A cells were isolated from the human esophageal squamous carcinoma cell line TE11 and the effects of anti-PDPN neutralizing antibody as well as PDPN gene knockout on platelet-induced EMT-related gene expression were measured. Also, the effects of PDPN deficiency on cellular invasive ability and motility were assessed.

Results

PDPN-null cells were able to provoke platelet aggregation, suggesting that PDPN contribution to platelet activation in these cells is marginal. Nevertheless, expression of platelet-induced EMT-related genes, including vimentin, was impaired by PDPN-neutralizing antibody as well as PDPN deficiency, while their effects on TGF-β-induced gene expression were marginal. Unexpectedly, PDPN gene ablation, at least in either allele, engendered spontaneous N-cadherin upregulation and claudin-1 downregulation. Despite these seemingly EMT-like alterations, PDPN deficiency impaired cellular motility and invasive ability even after TGF-β-induced EMT induction.

Conclusions

These results suggested that, while PDPN seems to function in favor of maintaining the epithelial state of this cell line, it is indispensable for platelet-mediated induction of particular mesenchymal marker genes as well as the potentiation of motility and invasion capacity.

Integrative approach to cytologic and molecular diagnosis of malignant pleural mesothelioma

The global incidence of malignant mesothelioma (MM) causes considerable disease burden, suffering and health care costs. Beside preventive measures and ban the use of asbestos, early diagnosis would largely improve the chance of curative treatment. Current histologic criteria, however, requiring presence of invasion in the surrounding fatty tissue fail to identify MM in sufficiently early stage. Unilateral accumulation of pleural effusion is one of the earliest clinical manifestations of MM that occurs in approximately 90% of the patients. Therapeutic thoracocenthesis is necessary to remove the fluid and to relieve patients’ symptoms. This effusion is easily accessible and offers early and minimally invasive diagnosis by combining cytology with immunologic, molecular- and biomarker analyses. Typically, the fluid is rich in malignant cells and cell groups, but incipient stages of the disease may be difficult to recognize as the malignant cells can be masked by presence of inflammatory or reactive mesothelial cells. Recurrent, hemorrhagic and cell rich effusion should always be suspicious for MM and adequately prepared and analyzed to provide necessary information for subsequent therapy. Importantly, early detection of MM by integrating cytology and molecular approaches has high sensitivity and positive predictive value and has a major impact on patient survival. Thus, a conclusive positive MM cytology should lead to treatment without delay. This review summarizes molecular and diagnostic criteria of MM diagnosis.

[Cancer-associated fibroblasts and their significance in tumor progression]

Carcinogenesis and tumor progression are not caused not only by malignant epithelial cells, but also by the tumor stroma around cancer stem cells which performs regulatory, nutritional and 'framework' functions. It is represented by mesenchymal cells of various types predominantly by cancer-associated fibroblasts (CAF). αSMA, FAP-1, desmin, podoplanin, neuron-glial antigen 2 (NG2), PDGFR-α and -β are used for CAF identification but there is no universal markers due to the plasticity of the cell population that underlies the subpopulation division CAF. CAF subpopulations are not described for many tumor types. Recently, evidence has accumulated that CAFs mediate many adverse processes in the tumor, including can support stromal inflammation and cause fibrosis. By forming a niche in cancer stem cells, CAFs mediate chemoresistance and the appearance of dormant metastases. The study of the role of CAF will allow not only to form a fundamentally new understanding of the mechanisms of carcinogenesis, but also to create new diagnostic and therapeutic targets for treating tumors.

Graphene-based biosensors for the detection of prostate cancer protein biomarkers: a review

Prostate cancer (PC) is the sixth most common cancer type in the world, which causes approximately 10% of total cancer fatalities. The detection of protein biomarkers in body fluids is the key topic for the diagnosis and prognosis of PC. Highly sensitive screening of PC is the most effective approach for reducing mortality. Thus, there are a growing number of literature that recognizes the importance of new technologies for early diagnosis of PC. Graphene is playing an important role in the biosensor field with remarkable physical, optical, electrochemical and magnetic properties. Many recent studies demonstrated the potential of graphene materials for sensitive detection of protein biomarkers. In this review, the graphene-based biosensors toward PC analysis are mainly discussed in two groups: Firstly, novel biosensor interfaces were constructed through the modification of graphene materials onto sensor surfaces. Secondly, ingenious signal amplification strategies were developed using graphene materials as catalysts or carriers. Graphene-based biosensors have exhibited remarkable performance with high sensitivities, wide detection ranges, and long-term stabilities.

Podoplanin in Inflammation and Cancer

Podoplanin is a small cell-surface mucin-like glycoprotein that plays a crucial role in the development of the alveoli, heart, and lymphatic vascular system. Emerging evidence indicates that it is also involved in the control of mammary stem-cell activity and biogenesis of platelets in the bone marrow, and exerts an important function in the immune response. Podoplanin expression is upregulated in different cell types, including fibroblasts, macrophages, T helper cells, and epithelial cells, during inflammation and cancer, where it plays important roles. Podoplanin is implicated in chronic inflammatory diseases, such as psoriasis, multiple sclerosis, and rheumatoid arthritis, promotes inflammation-driven and cancer-associated thrombosis, and stimulates cancer cell invasion and metastasis through a variety of strategies. To accomplish its biological functions, podoplanin must interact with other proteins located in the same cell or in neighbor cells. The binding of podoplanin to its ligands leads to modulation of signaling pathways that regulate proliferation, contractility, migration, epithelial⁻mesenchymal transition, and remodeling of the extracellular matrix. In this review, we describe the diverse roles of podoplanin in inflammation and cancer, depict the protein ligands of podoplanin identified so far, and discuss the mechanistic basis for the involvement of podoplanin in all these processes.

Podoplanin and SOX2 Expression in CIN 3-like Squamous Cell Carcinoma of the Cervix

Squamous cell carcinoma (SCC) of the uterine cervix occasionally demonstrates a deceptive growth pattern that mimics endocervical crypt involvement by cervical intraepithelial neoplasia, grade 3 (CIN 3). Such CIN 3-like SCCs may be misinterpreted as noninvasive or minimally invasive leading to delays in diagnosis. Little is known of the factors that influence the growth patterns of cervical SCC but we suggested recently that CIN 3-like tumors might demonstrate "collective cellular invasion," which is characterized by a retained epithelial phenotype. This contrasts with the more overtly infiltrative growth of conventional SCC, which exhibits features suggestive of epithelial-mesenchymal transition. In the current study we investigated podoplanin (PP) and SOX2 expression in normal squamous epithelium, in CIN 3 and in 16 CIN 3-like SCCs 11 of which also showed a conventional invasive component. Compared with normal epithelium, CIN 3 often showed a focal loss of basal PP staining and most cases showed increased, typically diffuse, SOX2 expression. Although the immunohistochemical findings were not uniform, they generally supported collective cellular invasion in CIN 3-like tumor areas as these were often PP positive and showed diffuse SOX2 expression. In contrast, most conventional SCCs showed only focal SOX2 staining and they were typically negative, or only focally positive, for PP. The staining patterns did not reliably distinguish CIN 3 from CIN 3-like SCC. Small infiltrative tumor nests around the margins of CIN 3 or deeply invasive CIN 3-like SCC often showed a localized reduction in SOX2 expression suggesting SOX2 downregulation during the transition to invasive growth.

Podoplanin: An emerging cancer biomarker and therapeutic target

Podoplanin (PDPN) is a transmembrane receptor glycoprotein that is upregulated on transformed cells, cancer associated fibroblasts and inflammatory macrophages that contribute to cancer progression. In particular, PDPN increases tumor cell clonal capacity, epithelial mesenchymal transition, migration, invasion, metastasis and inflammation. Antibodies, CAR-T cells, biologics and synthetic compounds that target PDPN can inhibit cancer progression and septic inflammation in preclinical models. This review describes recent advances in how PDPN may be used as a biomarker and therapeutic target for many types of cancer, including glioma, squamous cell carcinoma, mesothelioma and melanoma.

Podoplanin expression in peritumoral keratinocytes predicts aggressive behavior in extramammary Paget's disease

BACKGROUND

Recent studies have demonstrated podoplanin expression in several tumors, which has been associated with lymph node metastasis and poor prognosis. Podoplanin expression in peritumoral cells such as cancer-associated fibroblasts also correlates with tumor progression in several cancers. However, podoplanin expression and its association with extramammary Paget's disease (EMPD) remain unclear.

OBJECTIVE

In this study, we examined whether the presence of podoplanin expression in tumor cells or peritumoral basal keratinocytes correlated with aggressive behavior in patients with EMPD and investigated the mechanisms of podoplanin-mediated tumor invasion in this disorder.

METHODS

Skin samples of 37 patients with EMPD were investigated by immunohistochemical analysis. The functions of podoplanin in keratinocytes were examined in vitro by RT-PCR and with invadopodia gelatin-degradation assays using HaCaT cells.

RESULTS

Podoplanin was not identified in tumor cells in all cases. Podoplanin expression in peritumoral basal keratinocytes was observed in 25 patients (67.6%). In in situ EMPD, 50% of cases (9 in 18) exhibited podoplanin-positive keratinocytes, whereas 84.2% (16 in 19) demonstrated positive staining in invasive EMPD (P<0.05). Podoplanin expression in peritumoral keratinocytes was also associated with tumor thickness (P<0.005). By immunohistochemical analysis, podoplanin-positive peritumoral keratinocytes were found to be negative for E-cadherin, one of the major adhesion molecules of keratinocytes, which might contribute to tumor invasion into the dermis through a crack in the basal cell layer induced by down-regulation of cell adhesion therein. We further found that podoplanin-positive keratinocytes exhibited invadopodia, which are thought to function in the migration of cancer cells through tissue barriers, indicating that podoplanin-positive peritumoral basal keratinocytes might assist tumor invasion by degrading the extracellular matrix.

CONCLUSION

The presence of podoplanin expression in peritumoral keratinocytes correlates with aggressive behavior in EMPD and might therefore serve as a useful prognostic marker for patients with EMPD.

Altered Dermal Fibroblasts in Systemic Sclerosis Display Podoplanin and CD90

Tissue injury triggers the activation and differentiation of multiple cell types to minimize damage and initiate repair processes. In systemic sclerosis, these repair processes appear to run unchecked, leading to aberrant remodeling and fibrosis of the skin and multiple internal organs, yet the fundamental pathological defect remains unknown. We describe herein a transition wherein the abundant CD34(+) dermal fibroblasts present in healthy human skin disappear in the skin of systemic sclerosis patients, and CD34(-), podoplanin(+), and CD90(+) fibroblasts appear. This transition is limited to the upper dermis in several inflammatory skin diseases, yet in systemic sclerosis, it can occur in all regions of the dermis. In vitro, primary dermal fibroblasts readily express podoplanin in response to the inflammatory stimuli tumor necrosis factor and IL-1β. Furthermore, we show that on acute skin injury in both human and murine settings, this transition occurs quickly, consistent with a response to inflammatory signaling. Transitioned fibroblasts partially resemble the cells that form the reticular networks in organized lymphoid tissues, potentially linking two areas of fibroblast research. These results allow for the visualization and quantification of a basic stage of fibroblast differentiation in inflammatory and fibrotic diseases in the skin.

Dual use of E-cadherin and D2-40 immunostaining in unusual meningioma subtypes

OBJECTIVES

Meningiomas usually can be readily diagnosed on H&E alone, although occasionally immunohistochemistry (IHC) confirmation is desirable. Studies exploring the diagnostic utility of either podoplanin (D2-40) or E-cadherin IHC in meningiomas have conflicted, and no studies exist in which the two IHCs have been used in combination for diagnosis.

METHODS

E-cadherin and D2-40 IHC was performed on 77 meningiomas (31 ordinary; eight microcystic; four rare myxoid; six metaplastic; six invasive of orbit, muscle, and/or soft tissue; two metastatic; six brain-invasive World Health Organization [WHO] grade II, nine non-brain-invasive WHO grade II; and five anaplastic WHO grade III), with semi-quantitative scoring on a three-tier scale (0, focal [1+], strong/diffuse [2+]).

RESULTS

All meningiomas were either E-cadherin or D2-40 IHC+, with 69 of 77 showing dual immunostaining, most at the 2+ level. No downregulation of E-cadherin IHC was found in invasive or high-grade meningiomas.

CONCLUSIONS

Dual E-cadherin/D2-40 IHC can supplement diagnosis of meningioma.

Multiple congenital granular cell epulis: case report and immunohistochemical profile with emphasis on vascularization

Congenital granular cell epulis is a rare benign soft tissue lesion arising from the alveolar ridge in neonates. A rare case of multiple congenital granular cell epulis is reported, alongside a description of its vascular immunohistochemical profile. A female newborn presented with two exophytic pedunculated red nodules located on the alveolar ridge between the future eruption sites of the incisors and canines of the mandible and maxilla. A conservative surgical excision was performed on the second day of life. Histology revealed proliferation of round granular cells containing an abundant eosinophilic cytoplasm with basophilic nuclei, ranging from round to oval in shape. Numerous blood vessels were also seen. Immunohistochemical analysis of the granular cells revealed positivity for CD68, D2-40, Ki67, VEGF, and FGF and negativity for S100, CD34, and CD105. Immunostaining for CD34, CD105, and D2-40 confirmed the presence of a large number of blood and lymphatic vessels. Although rare, an understanding of this lesion is paramount for correct diagnosis and appropriate treatment. In the present report, the immunohistochemical profile confirmed increased vascularization, proving that these lesions are composed of not only new and preexisting blood vessels, but also lymphatic vessels.

Expression of mesothelioma-related markers in meningiomas: an immunohistochemical study

Background. Meningiomas are common intracranial tumors. Recently, histogenetic and phenotypic similarities between meningiomas and mesotheliomas have been proposed. We were interested in whether these similarities are reflected on the immunohistochemical level, which would add new potentially diagnostic markers for meningiomas. Methods. The expression of mesothelioma-related markers (D2-40, Calretinin, Keratin 5/6, WT1, and Methotheioma-Ab1) was investigated in 87 cases of meningiomas and compared to EMA expression. Results. 73.6% of meningioma cases were grade I, 20.7% were grade II, and 5.7% were grade III. 83.9% of meningioma cases were classical and 16.1% had special nonmeningothelial features. D2-40 was expressed in 37.9% of cases and was significantly restricted to classical meningiomas. Calretinin and WT1 were negative while Keratin 5/6 and Mesothelioma-Ab1 were weakly expressed in classical variants (5.7% and 3.4%, resp.). EMA was consistently expressed in all cases. Its expression was significantly higher than that of mesothelioma-related markers; this held true also when D2-40 expression was considered separately. Conclusions. Mesothelioma-related markers are not extensively expressed in meningiomas, a finding that argues against their proposed histogenetic and phenotypic similarities. Compared to EMA, the significantly lower expression of mesothelioma-related markers and their restricted expression to classical meningioma variants hamper their potential future use as diagnostic markers for meningioma.

Podoplanin expression in cancer-associated fibroblasts predicts aggressive behavior in melanoma

BACKGROUND

Recent studies have showed podoplanin expression in several tumors, which has been associated with lymph node metastasis and poor prognosis. Podoplanin expression in cancer-associated fibroblasts also correlates with tumor progression. However, the association of podoplanin expression with melanomas remains unclear.

METHODS

To clarify the prognostic significance of podoplanin in melanoma, podoplanin expression in tumor cells and cancer-associated fibroblasts was examined by immunohistochemistry in tissue samples collected from 55 melanoma patients.

RESULTS

Podoplanin expression in tumor cells was identified in 38 patients (69.1%) but did not show correlation with characteristics of tumor progression such as tumor thickness (p = 0.52) and sentinel lymph node (SLN) metastasis (p = 0.79). Podoplanin expression in cancer-associated fibroblasts was observed in 25 patients (45.5%), 11 of whom (44.0%) had SLN metastasis. In contrast, only 4 of 30 patients (13.3%) with podoplanin-negative cancer-associated fibroblasts exhibited SLN metastasis. Podoplanin-positive cancer-associated fibroblasts were associated with increased tumor thickness and SLN metastasis. Furthermore, patients with podoplanin-positive cancer-associated fibroblasts had poorer survival than those with podoplanin-negative cancer-associated fibroblasts (p = 0.0148).

CONCLUSION

The presence of podoplanin expression in cancer-associated fibroblasts correlates with aggressive behavior in melanoma and might therefore serve as a useful prognostic factor for patients with melanoma.