Tumor lymphangiogenesis and metastasis to lymph nodes induced by cancer cell expression of podoplanin

The role of micrometastasis in high-risk skin cancers

The propensity to metastasize is the most important prognostic indicator for solid cancers. New insights into the mechanisms of early carcinogenesis have revealed micrometastases are generated far earlier than previously thought. Evidence supports a synergistic relationship between vascular and lymphatic seeding which can occur before there is clinical evidence of a primary tumour. Early vascular seeding prepares distal sites for colonisation while regional lymphatics are co-opted to promote facilitative cancer cell mutations. In response, the host mounts a global inflammatory and immunomodulatory response towards these cells supporting the concept that cancer is a systemic disease. Cancer staging systems should be refined to better reflect cancer cell loads in various tissue compartments while clinical perspectives should be broadened to encompass this view when approaching high-risk cancers. Measured adjunctive therapies implemented earlier for low-volume, in-transit cancer offers the prospect of preventing advanced disease and the need for heroic therapeutic interventions. This review seeks to re-appraise how we view the metastatic process for solid cancers. It will explore in-transit metastasis in the context of high-risk skin cancer and how it dictates disease progression. It will also discuss how these implications will influence our current staging systems and its consequences on management.

Expression of PTGS2 along with genes regulating VEGF signalling pathway and association with high-risk factors in locally advanced oral squamous cell carcinoma

BACKGROUND

PTGS2 encodes cyclooxygenase-2 (COX-2), which catalyses the committed step in prostaglandin synthesis. Various in vivo and in vitro data suggest that COX-2 mediates the VEGF signalling pathway. In silico analysis performed in TCGA, PanCancer Atlas for head and neck cancers, demonstrated significant expression and co-expression of PTGS2 and genes that regulate VEGF signalling. This study was designed to elucidate the expression pattern of PTGS2 and genes regulating VEGF signalling in patients with locally advanced oral squamous cell carcinoma (OSCC).

METHODOLOGY

Tumour and normal tissue samples were collected from patients with locally advanced OSCC. RNA was isolated from tissue samples, followed by cDNA synthesis. The cDNA was used for gene expression analysis (RT-PCR) using target-specific primers. The results obtained were compared with the in silico gene expression of the target genes in the TCGA datasets. Co-expression analysis was performed to establish an association between PTGS2 and VEGF signalling genes.

RESULTS

Tumour and normal tissue samples were collected from 24 OSCC patients. Significant upregulation of PTGS2 expression was observed. Furthermore, VEGFA, KDR, CXCR1 and CXCR2 were significantly upregulated in tumour samples compared with paired normal samples, except for VEGFB, whose expression was not statistically significant. A similar expression pattern was observed in silico, except for CXCR2 which was highly expressed in the normal samples. Co-expression analysis showed a significant positive correlation between PTGS2 and VEGF signalling genes, except for VEGFB which showed a negative correlation.

CONCLUSION

PTGS2 and VEGF signalling genes are upregulated in OSCC, which has a profound impact on clinical outcomes.

A novel PDPN antagonist peptide CY12-RP2 inhibits melanoma growth via Wnt/β-catenin and modulates the immune cells

BACKGROUND

Podoplanin (PDPN) is a highly conserved, mucin-type protein specific to the lymphatic system. Overexpression of PDPN is associated with the progression of various solid tumors, and plays an important roles in the tumor microenvironment by regulating the immune system. However, the role of PDPN-mediated signal activation in the progression of melanoma is still unknown.

METHODS

PDPN expression was first analyzed in 112 human melanoma tissue microarrays and melanoma cell lines. Functional experiments including proliferation, clone formation, migration, and metastasis were utilized to identify the suppressive effects of PDPN. The Ph.D.TM-12 Phage Display Peptide Library was used to obtain a PDPN antagonist peptide, named CY12-RP2. The immunofluorescence, SPR assay, and flow cytometry were used to identify the binding specificity of CY12-RP2 with PDPN in melanoma cells. Functional and mechanistic assays in vivo and in vitro were performed for discriminating the antitumor and immune activation effects of CY12-RP2.

RESULTS

PDPN was overexpressed in melanoma tissue and cells, and inhibited melanoma cells proliferation, migration, and metastasis by blocking the EMT and Wnt/β-catenin pathway. PDPN antagonistic peptide, CY12-RP2, could specifically bind with PDPN, suppressing melanoma various functions inducing apoptosis in both melanoma cells and 3D spheroids. CY12-RP2 also enhanced the anti-tumor capacity of PBMC, and inhibited melanoma cells growth both in xenografts and allogeneic mice model. Moreover, CY12-RP2 could inhibit melanoma lung metastasis, and abrogated the immunosuppressive effects of PDPN by increasing the proportion of CD3 + CD4 + T cells, CD3 + CD8 + T cells, CD49b + Granzyme B + NK cells, and CD11b + CD86 + M1-like macrophages and the levels of IL-1β, TNF-α, and IFN-γ.

CONCLUSIONS

This study has demonstrated the important role of PDPN in the progression of melanoma and formation of immunosuppressive environment, and provided a potential approach of treating melanoma using the novel CY12-RP2 peptide. In melanoma, PDPN is overexpressed in the cancer cells, and promotes melanoma cells growth and metastasis through activating the Wnt/β-catenin pathway. Treatment with the PDPN antagonistic peptide CY12-RP2 could not only inhibit the melanoma growth and metastasis both in vitro and in vivo through Wnt/β-catenin pathway blockade, but also abrogate the immunosuppressive effects of PDPN through modulating immune cells.

Genome-wide analyses reveal the contribution of somatic variants to the immune landscape of multiple cancer types

It has been well established that cancer cells can evade immune surveillance by mutating themselves. Understanding genetic alterations in cancer cells that contribute to immune regulation could lead to better immunotherapy patient stratification and identification of novel immune-oncology (IO) targets. In this report, we describe our effort of genome-wide association analyses across 22 TCGA cancer types to explore the associations between genetic alterations in cancer cells and 74 immune traits. Results showed that the tumor microenvironment (TME) is shaped by different gene mutations in different cancer types. Out of the key genes that drive multiple immune traits, top hit KEAP1 in lung adenocarcinoma (LUAD) was selected for validation. It was found that KEAP1 mutations can explain more than 10% of the variance for multiple immune traits in LUAD. Using public scRNA-seq data, further analysis confirmed that KEAP1 mutations activate the NRF2 pathway and promote a suppressive TME. The activation of the NRF2 pathway is negatively correlated with lower T cell infiltration and higher T cell exhaustion. Meanwhile, several immune check point genes, such as CD274 (PD-L1), are highly expressed in NRF2-activated cancer cells. By integrating multiple RNA-seq data, a NRF2 gene signature was curated, which predicts anti-PD1 therapy response better than CD274 gene alone in a mixed cohort of different subtypes of non-small cell lung cancer (NSCLC) including LUAD, highlighting the important role of KEAP1-NRF2 axis in shaping the TME in NSCLC. Finally, a list of overexpressed ligands in NRF2 pathway activated cancer cells were identified and could potentially be targeted for TME remodeling in LUAD.

Modeling lymphangiogenesis: Pairing in vitro and in vivo metrics

Lymphangiogenesis is the mechanism by which the lymphatic system develops and expands new vessels facilitating fluid drainage and immune cell trafficking. Models to study lymphangiogenesis are necessary for a better understanding of the underlying mechanisms and to identify or test new therapeutic agents that target lymphangiogenesis. Across the lymphatic literature, multiple models have been developed to study lymphangiogenesis in vitro and in vivo. In vitro, lymphangiogenesis can be modeled with varying complexity, from monolayers to hydrogels to explants, with common metrics for characterizing proliferation, migration, and sprouting of lymphatic endothelial cells (LECs) and vessels. In comparison, in vivo models of lymphangiogenesis often use genetically modified zebrafish and mice, with in situ mouse models in the ear, cornea, hind leg, and tail. In vivo metrics, such as activation of LECs, number of new lymphatic vessels, and sprouting, mirror those most used in vitro, with the addition of lymphatic vessel hyperplasia and drainage. The impacts of lymphangiogenesis vary by context of tissue and pathology. Therapeutic targeting of lymphangiogenesis can have paradoxical effects depending on the pathology including lymphedema, cancer, organ transplant, and inflammation. In this review, we describe and compare lymphangiogenic outcomes and metrics between in vitro and in vivo studies, specifically reviewing only those publications in which both testing formats are used. We find that in vitro studies correlate well with in vivo in wound healing and development, but not in the reproductive tract or the complex tumor microenvironment. Considerations for improving in vitro models are to increase complexity with perfusable microfluidic devices, co-cultures with tissue-specific support cells, the inclusion of fluid flow, and pairing in vitro models of differing complexities. We believe that these changes would strengthen the correlation between in vitro and in vivo outcomes, giving more insight into lymphangiogenesis in healthy and pathological states.

Extracellular matrix remodeling in tumor progression and immune escape: from mechanisms to treatments

The malignant tumor is a multi-etiological, systemic and complex disease characterized by uncontrolled cell proliferation and distant metastasis. Anticancer treatments including adjuvant therapies and targeted therapies are effective in eliminating cancer cells but in a limited number of patients. Increasing evidence suggests that the extracellular matrix (ECM) plays an important role in tumor development through changes in macromolecule components, degradation enzymes and stiffness. These variations are under the control of cellular components in tumor tissue via the aberrant activation of signaling pathways, the interaction of the ECM components to multiple surface receptors, and mechanical impact. Additionally, the ECM shaped by cancer regulates immune cells which results in an immune suppressive microenvironment and hinders the efficacy of immunotherapies. Thus, the ECM acts as a barrier to protect cancer from treatments and supports tumor progression. Nevertheless, the profound regulatory network of the ECM remodeling hampers the design of individualized antitumor treatment. Here, we elaborate on the composition of the malignant ECM, and discuss the specific mechanisms of the ECM remodeling. Precisely, we highlight the impact of the ECM remodeling on tumor development, including proliferation, anoikis, metastasis, angiogenesis, lymphangiogenesis, and immune escape. Finally, we emphasize ECM "normalization" as a potential strategy for anti-malignant treatment.

Extracellular Vesicles: New Classification and Tumor Immunosuppression

Extracellular vesicles (EVs) are cell-derived membrane-surrounded vesicles carrying various types of molecules. These EV cargoes are often used as pathophysiological biomarkers and delivered to recipient cells whose fates are often altered in local and distant tissues. Classical EVs are exosomes, microvesicles, and apoptotic bodies, while recent studies discovered autophagic EVs, stressed EVs, and matrix vesicles. Here, we classify classical and new EVs and non-EV nanoparticles. We also review EVs-mediated intercellular communication between cancer cells and various types of tumor-associated cells, such as cancer-associated fibroblasts, adipocytes, blood vessels, lymphatic vessels, and immune cells. Of note, cancer EVs play crucial roles in immunosuppression, immune evasion, and immunotherapy resistance. Thus, cancer EVs change hot tumors into cold ones. Moreover, cancer EVs affect nonimmune cells to promote cellular transformation, including epithelial-to-mesenchymal transition (EMT), chemoresistance, tumor matrix production, destruction of biological barriers, angiogenesis, lymphangiogenesis, and metastatic niche formation.

Lymphatic Vascular Density, the Expression of Podoplanin and Tumor Budding in Oral Squamous Cell Carcinoma

BACKGROUND

Notwithstanding recent advances in oral squamous cell carcinoma (OSCC) management, its mortality rate is still high. It is imperative to investigate new parameters that are complementary to clinical staging for OSCC to provide better prognostic insight. The presence of isolated neoplastic cells or small clusters of up to four cells at the tumor's invasive front, called tumor budding, is a morphological marker of OSCC with prognostic value. Increased lymphatic vascular density (LVD) and a high expression of podoplanin in neoplastic cells have also been associated with worse prognosis in OSCC. To investigate these markers in OSCC, we evaluated differences in LVD and the expression of podoplanin in neoplastic cells between tumors with high-intensity tumor budding versus low-intensity or no tumor budding. In the samples of high-intensity budding, differences in those parameters between the​​ budding area and the area outside the budding were also evaluated. Furthermore, the study assessed differences in LVD and in the expression of podoplanin in neoplastic cells concerning OSCC clinicopathological characteristics.

METHODS

To those ends, we subjected 150 samples of OSCC to immunohistochemistry to evaluate the intensity of tumor budding (via multi-cytokeratin immunostaining). Moreover, the 150 samples of OSCC and 15 specimens of normal oral mucosa (used as a control) were employed to assess LVD and the expression of podoplanin (in neoplastic cells of OSCC and in the lining epithelium of normal oral mucosa), both via podoplanin immunostaining. Data were processed into descriptive and analytical statistics.

RESULTS

No differences were observed neither in the LVD nor in the expression of podoplanin in neoplastic cells concerning sex, age, tobacco smoking, tumor location and tumor size. The LVD was greater in OSCC and in tumors with high-intensity budding than in normal mucosa but did not differ between normal mucosa and tumors with low-intensity or no tumor budding. The data analyses also revealed that LVD was greater in tumors with high-intensity tumor budding than in tumors with low-intensity or no budding and showed no difference in LVD between the budding area and the area outside the budding. When compared to the lining epithelium of the normal mucosa, the expression of podoplanin was greater in neoplastic cells of OSCC, tumors with high-intensity budding and tumors with low-intensity or no tumor budding. The expression of podoplanin in neoplastic cells was also greater in tumors with high-intensity budding and, within those tumors, greater in the budding area than in the area outside de budding.

CONCLUSION

Those findings support the hypothesis that tumor budding is a biological phenomenon associated with the progression and biological behavior of OSCC.

Advances on the roles of tenascin-C in cancer

The roles of the extracellular matrix molecule tenascin-C (TNC) in health and disease have been extensively reviewed since its discovery over 40 years ago. Here, we will describe recent insights into the roles of TNC in tumorigenesis, angiogenesis, immunity and metastasis. In addition to high levels of expression in tumors, and during chronic inflammation, and bacterial and viral infection, TNC is also expressed in lymphoid organs. This supports potential roles for TNC in immunity control. Advances using murine models with engineered TNC levels were instrumental in the discovery of important functions of TNC as a danger-associated molecular pattern (DAMP) molecule in tissue repair and revealed multiple TNC actions in tumor progression. TNC acts through distinct mechanisms on many different cell types with immune cells coming into focus as important targets of TNC in cancer. We will describe how this knowledge could be exploited for cancer disease management, in particular for immune (checkpoint) therapies.

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

INTRODUCTION

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.

METHODS

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.

RESULTS

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.

CONCLUSION

Taken together, our results suggest that upregulation of podoplanin may be associated with a stimulation of lymphatic metastasis in head and neck cancer.

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.

Immunohistochemical and immunofluorescence expression profile of lymphatic endothelial cell markers in oral cancer

Lymphangiogenesis makes an important contribution to the tumour microenvironment (TME), but little is known about this in oral squamous cell carcinoma (OSCC). Archival formalin-fixed paraffin-embedded specimens (28 OSCC, 10 inflamed and 6 normal oral mucosa controls) were processed using immunohistochemistry (IHC) with antibodies against lymphatic markers D2-40 (podoplanin), LYVE-1, VEGFR3 and Prox1. After the endothelial cells had been highlighted by the various markers for lymphatic endothelium, the positive stained cells and vessels were identified and counted in a systematic manner to determine microvessel density. Double-labelling immunofluorescence (DLIF) was used to investigate the specificity of D2-40 and LYVE-1 to lymphatic endothelial cells (LECs) as opposed to blood ECs. There was higher D2-40 and Prox1 lymphatic vessel density (P = .001) in the OSCC group when compared with both control groups. Some malignant keratinocytes expressed lymphatic markers, as did a much smaller number of epithelial cells in the control groups. DLIF showed that no vessels co-expressed D2-40/CD34 or LYVE/CD34. Some D2/40⁺ LVs were LYVE^- . D2-40 was the most specific LEC marker in OSCC tissues. These results establish that the OSCC TME contains significantly more lymphatic vessels expressing D2-40 and Prox1 than the control groups, which may play a role in facilitating lymphatic invasion and metastases.

Podoplanin Drives Motility of Active Macrophage via Regulating Filamin C During Helicobacter pylori Infection

Podoplanin (Pdpn) is a mucin-type transmembrane protein that has been implicated in multiple physiological settings including lymphangiogenesis, platelet aggregation, and cancer metastasis. Here, we reported an absence of Pdpn transcript expression in the resting mouse monocytic macrophages, RAW264.7 cells; intriguingly, a substantial upregulation of Pdpn was observed in activated macrophages following Helicobacter pylori or lipopolysaccharide stimulation. Pdpn-knockout macrophages demonstrated intact phagocytic and intracellular bactericidal activities comparable to wild type but exhibited impaired migration due to attenuated filopodia formation. In contrast, an ectopic expression of Pdpn augmented filopodia protrusion in activated macrophages. NanoString analysis uncovered a close dependency of Filamin C gene on the presence of Pdpn, highlighting an involvement of Filamin C in modulation of actin polymerization activity, which controls cell filopodia formation and migration. In addition, interleukin-1β production was significantly declined in the absence of Pdpn, suggesting a role of Pdpn in orchestrating inflammation during H. pylori infection besides cellular migration. Together, our findings unravel the Pdpn network that modulates movement of active macrophages.

CD147 Promotes Tumor Lymphangiogenesis in Melanoma via PROX-1

Simple Summary

Melanoma is one of the most aggressive skin cancers, characterized by metastasis to the lymph nodes and a high capacity to develop drug resistance. There is a lack of knowledge on the mechanisms contributing to lymphatic vessel formation and metastasis regulation in malignant melanoma. We previously reported the involvement of CD147, a transmembrane glycoprotein overexpressed in melanoma, in the regulation of the tumor microenvironment and angiogenesis. The aim of our study was to further determine how CD147 is involved in lymphangiogenesis regulation. Our results revealed that high CD147 expression is correlated with the number of lymphatic vessels in the human melanoma lymph nodes and that paracrine CD147 upregulates lymphangiogenesis through lymphangiogenic mediators in vitro and in vivo, suggesting that CD147 could be a promising target for melanoma-associated lymphangiogenesis inhibition.

Abstract

Malignant melanoma is one of the most aggressive skin cancers and is characterized by early lymph node metastasis and the capacity to develop resistance to therapies. Hence, understanding the regulation of lymphangiogenesis through mechanisms contributing to lymphatic vessel formation represents a treatment strategy for metastatic cancer. We have previously shown that CD147, a transmembrane glycoprotein overexpressed in melanoma, regulates the angiogenic process in endothelial cells. In this study, we show a correlation between high CD147 expression levels and the number of lymphatic vessels expressing LYVE-1, Podoplanin, and VEGFR-3 in human melanoma lymph nodes. CD147 upregulates in vitro lymphangiogenesis and its related mediators through the PROX-1 transcription factor. In vivo studies in a melanoma model confirmed that CD147 is involved in metastasis through a similar mechanism as in vitro. This study, demonstrating the paracrine role of CD147 in the lymphangiogenesis process, suggests that CD147 could be a promising target for the inhibition of melanoma-associated lymphangiogenesis.

Podoplanin is required for tumor cell invasion in cutaneous squamous cell carcinoma

The invasiveness of late-stage cutaneous squamous cell carcinoma (cSCC) is associated with poor patients' prognosis and linked to strong upregulation of the glycoprotein Podoplanin (PDPN) in cancer cells. However, the function of PDPN in these processes in cSCC carcinogenesis has not been characterized in detail yet. Employing a CRISPR/Cas9-based loss-of-function approach on murine cSCC cells, we show that the loss of Pdpn results in decreased migration and invasion in vitro. Complementing these in vitro studies, labelled murine control and Pdpn knockout cells were injected orthotopically into the dermis of nude mice to recapitulate the formation of human cSCC displaying a well-differentiated morphology with a PDPN-positive reaction in fibroblasts in the tumor stroma. Smaller tumors were observed upon Pdpn loss, which is associated with reduced tumor cell infiltration into the stroma. Utilizing Pdpn mutants in functional experiments in vitro, we provide evidence that both the intra- and extracellular domains are essential for cancer cell invasion. These findings underline the critical role of PDPN in cSCC progression and highlight potential therapeutic strategies targeting PDPN-dependent cancer cell invasion, especially in late-stage cSCC patients.

The mechanisms and reversal strategies of tumor radioresistance in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of most lethal malignancies with high aggressive potential in the world. Radiotherapy is used as one curative treatment modality for ESCC patients. Due to radioresistance, the 5-year survival rates of patients after radiotherapy is less than 20%. Tumor radioresistance is very complex and heterogeneous. Cancer-associated fibroblasts (CAFs), as one major component of tumor microenvironment (TME), play critical roles in regulating tumor radioresponse through multiple mechanisms and are increasingly considered as important anti-cancer targets. Cancer stemness, which renders cancer cells to be extremely resistant to conventional therapies, is involved in ESCC radioresistance due to the activation of Wnt/β-catenin, Notch, Hedgehog and Hippo (HH) pathways, or the induction of epithelial-mesenchymal transition (EMT), hypoxia and autophagy. Non-protein-coding RNAs (ncRNAs), which account for more than 90% of the genome, are involved in esophageal cancer initiation and progression through regulating the activation or inactivation of downstream signaling pathways and the expressions of target genes. Herein, we mainly reviewed the role of CAFs, cancer stemness, non-coding RNAs as well as others in the development of radioresistance and clarify the involved mechanisms. Furthermore, we summarized the potential strategies which were reported to reverse radioresistance in ESCC. Together, this review gives a systematic coverage of radioresistance mechanisms and reversal strategies and contributes to better understanding of tumor radioresistance for the exploitation of novel intervention strategies in ESCC.

Molecular Alterations in Metastatic Ovarian Cancer From Gastrointestinal Cancer

Reports indicate that most metastatic ovarian cancer (MOC) originates from gastrointestinal cancer (GIC). Notably, GICs metastasize to the ovary frequently via 3 main routes including hematogenous spread, lymphogenous spread, and transcoelomic spread. Nonetheless, the mechanism of the progression remains unknown, and only a handful of literature exists on the molecular alteration implicated in MOC from GIC. This work collected existing evidence and literature on the vital molecules of the metastatic pathway and systematically analyzed them geared toward exploring the mechanism of the metastatic pathway of MOC. Further, this review described dominating molecular alteration in the metastatic process from cancer cells detaching away from lesions to arrive at the ovary, including factors for regulating signaling pathways in epithelial-interstitial transformation, invading, and surviving in the circulatory system or abdominal cavity. We interrogated the basis of the ovary as a distant metastatic site. This article provides new insights into the metastatic pathway and generates novel therapeutic targets for effective treatment and satisfactory outcomes in GIC patients.

Molecular dissection of CRC primary tumors and their matched liver metastases reveals critical role of immune microenvironment, EMT and angiogenesis in cancer metastasis

Metastasis is the primary cause of cancer mortality. The primary tumors of colorectal cancer (CRC) often metastasize to the liver. In this study, we have collected 122 samples from 45 CRC patients. Among them, 32 patients have primary tumors, adjacent normal tissues, and matched liver metastases. Thirteen patients have primary tumors without distant metastasis and matched normal tissues. Characterization of these samples was conducted by whole-exome and RNA sequencing and SNP6.0 analysis. Our results revealed no significant difference in genetic alterations including common oncogenic mutations, whole genome mutations and copy number variations between primary and metastatic tumors. We then assembled gene co-expression networks and identified metastasis-correlated gene networks of immune-suppression, epithelial–mesenchymal transition (EMT) and angiogenesis as the key events and potentially synergistic drivers associated with CRC metastasis. Further independent cohort validation using published datasets has verified that these specific gene networks are up regulated throughout the tumor progression. The gene networks of EMT, angiogenesis, immune-suppression and T cell exhaustion are closely correlated with the poor patient outcome and intrinsic anti-PD-1 resistance. These results offer insights of combinational strategy for the treatment of metastatic CRC.

Keratinocyte-Expressed Podoplanin is Dispensable for Multi-Step Skin Carcinogenesis

Podoplanin is a small transmembrane mucin-like glycoprotein that plays a crucial role in the development of the lung, heart and lymphatic vascular system. Its expression is upregulated in several types of human carcinomas and podoplanin levels in squamous cell carcinomas (SCCs) of the oral cavity and the lung correlate with cancer invasiveness, lymph node metastasis and shorter survival time of patients, indicating that podoplanin promotes tumor progression. However, its role during the early stages of carcinogenesis remain unclear. We generated mice with a specific deletion of podoplanin in epidermal keratinocytes (K5-Cre;Pdpn^flox/flox mice) and subjected them to a multistep chemical skin carcinogenesis regimen. The rate of tumor initiation; the number, size and differentiation of tumors; and the malignant transformation rate were comparable in K5-Cre;Pdpn^flox/flox mice and Pdpn^flox/flox control mice. However, tumor cell invasion was reduced in K5-Cre;Pdpn^flox/flox mice, in particular single cell invasion. Quantitative immunofluorescence analyses revealed that peritumoral lymphangiogenesis was reduced in K5-Cre;Pdpn^flox/flox mice, whereas there were no major changes of tumor-associated immune cell subpopulations. Thus, keratinocyte-expressed podoplanin is dispensable for the early steps of skin carcinogenesis but contributes to the progression of established tumors.

Neoadjuvant chemoradiation changes podoplanin expression in esophageal cancer patients

BACKGROUND

Locally advanced adenocarcinoma of the esophagus (EAC) and squamous cell carcinoma (ESCC) result in a worse prognosis. Neoadjuvant treatment improves survival, however, only for responders. The transmembrane glycoprotein podoplanin is overexpressed in squamous cell carcinomas, miRNA-363 is associated to its regulation in head and neck cancer.

AIM

To predict therapy response and prognosis markers, and targets for novel therapies would individualize treatments leading to more favourable outcomes.

METHODS

Expression of podoplanin protein has been visualized by immunohistochemistry in surgical specimens of 195 esophageal cancer patients who underwent transthoracic esophagectomy: 90 ESCC and 105 EAC with clinical T2-3, Nx, M0. One hundred and six patients received neoadjuvant chemoradiation. RNA was extracted from paraffin-embedded tissue, and miRNA-363 quantified by real-time TaqMan-real-time-PCR. D2-40 mab staining of > 5% was scored as high podoplanin expression (HPE). We related podoplanin and miRNA-363 expression to histopathologic response after neoadjuvant treatment and clinicopathological characteristics, such as histological tumor type, survival rate or clinical tumor category.

RESULTS

We confirmed expression of membrane-bound podoplanin in 90 ESCC patients. 26% showed HPE of > 5%. In addition, absence in EAC patients (only 2% with HPE) was shown. Lower podoplanin expression has been detected in resection-specimen of 58 ESCC patients after neoadjuvant (RTx/CTx) treatment, only 11% with HPE, compared to 50% HPE of 32 non-pretreated primary surgery patients, P = 0.0001. This difference of podoplanin expression was confirmed comparing pre-treatment biopsies with matching post-treatment surgical specimens, P < 0.001. Podoplanin has been identified as a prognostic marker in 32 patients that underwent primary surgery without neoadjuvant treatment. Low (0-5%) podoplanin expression was associated with better prognosis compared to patients with HPE, P = 0.013. Podoplanin expression has been associated with post-transcriptional regulation by miRNA-363. At a cut-off value of miR-363 < 7, lower miR-363 expression correlated with HPE in surgical tissue specimens of primary surgery patients, P = 0.013. Therefore, ESCC patients with miRNA-363 expression < 7 had a worse prognosis than patients expressing miRNA-363 ≥ 7, P = 0.049.

CONCLUSION

Analysis of the molecular process that leads to decrease in podoplanin expression during neoadjuvant treatment and its regulation may provide novel markers and targets to improve targeted therapy of ESCC.

Podoplanin expression in cutaneous squamous cell carcinomas and its relationship to histopathological prognostic factors

There are several clinicopathological factors associated with the prognosis of cutaneous squamous cell carcinomas (cSCC), but there remains a lack of molecular markers associated with cSCC tumor progression. This study aimed to determine the association between histopathological prognostic parameters and tumoral podoplanin expression in cSCC. This study included 63 paraffin embedded cSCC samples that were evaluated for tumoral podoplanin expression using immunohistochemistry. Among the 63 tumor samples, 27% lacked podoplanin expression, 22% exhibited diffuse podoplanin expression, and 51% exhibited focal podoplanin expression. Tumoral podoplanin expression was correlated with lymphovascular invasion and lymph node metastasis (p value < 0.05, for both). Additional research is needed to further delineate how the tumoral podoplanin expression can be used as a prognostic marker in patients with cSCC.

Membrane dynamics in cell migration

Migration of cells is required in multiple tissue-level processes, such as in inflammation or cancer metastasis. Endocytosis is an extremely regulated cellular process by which cells uptake extracellular molecules or internalise cell surface receptors. While the role of endocytosis of focal adhesions (FA) and plasma membrane (PM) turnover at the leading edge of migratory cells is wide known, the contribution of endocytic proteins per se in migration has been frequently disregarded. In this review, we describe the novel functions of the most well-known endocytic proteins in cancer cell migration, focusing on clathrin, caveolin, flotillins and GRAF1. In addition, we highlight the relevance of the macropinocytic pathway in amoeboid-like cell migration.

Expression of podoplanin correlates with prognosis in nasopharyngeal carcinoma

PURPOSE

Podoplanin is a membrane-bound glycoprotein that plays a role in lymphangiogenesis. Several studies suggest a role of podoplanin in head-and-neck cancer. The purpose of the current study was to evaluate the role of podoplanin as a prognostic marker in nasopharyngeal carcinoma.

METHODS

In a monocentric retrospective analysis, data of 42 patients with primary diagnosis of nasopharyngeal carcinoma (diagnosed between 2004 and 2017) were examined regarding the relationship between the immunohistochemically analyzed podoplanin expression status and corresponding clinical and oncological parameters.

RESULTS

The mean age was 56.6 years. The majority (61.9%) had an advanced tumor stage (T3-T4). The 5-year overall survival was 54%. 33% showed a positive expression of podoplanin. In patients with tumors with podoplanin expression, 5-year overall survival was 15%, while in patients with tumors without podoplanin expression, 5-year overall survival was 75% (p = 0.017, univariate analysis). In multivariate analysis, podoplanin expression was shown to be the only independent prognostic marker for nasopharyngeal carcinoma (p = 0.025).

CONCLUSION

This retrospective study shows that podoplanin expression is a potential prognostic marker for nasopharyngeal carcinomas. In the future, clinical use could filter out more aggressive courses and allow therapy escalation in those cases.

Podoplanin promotes cancer-associated thrombosis and contributes to the unfavorable overall survival in an ectopic xenograft mouse model of oral cancer

Background

Podoplanin (PDPN) is a transmembrane glycoprotein that mediates tumor cell-induced platelets aggregation in different cancer types. Emerging data indicate that PDPN is a marker for poor prognosis of human oral squamous cell carcinoma (OSCC). However, the functional impacts of PDPN on cancer formation and disease progression of OSCC remain to be elucidated.

Methods

The sublines of the OECM-1 oral cancer cells with PDPN knockdown or overexpression were established. The cellular characteristics and the ability to induce platelet aggregation of these cells lines were analyzed. An ectopic xenograft animal model by inoculating cancer cells into the anterior neck region of nude mice was established to investigate the functional impact of PDPN on disease progression and cancer-associated thrombosis of OSCC.

Results

PDPN promoted OSCC cell migration and invasion, but had no effect on cell proliferation in vitro and tumor growth in vivo. Co-incubation of PDPN-positive (PDPN⁺) OSCC cells with platelets induced platelet activation and aggregation. The mice bearing PDPN⁺ tumor had a decrease in overall survival despite that there was no gross appearance of distant metastasis. A speckled immunofluorescence staining pattern of platelet marker mCD41 was defined in the PDPN⁺ tumor sections and the intensity was greater than in the PDPN-low or negative tumor sections. Co-immunofluorescence staining of the tumor sections with mCD41 and the endothelial cell marker mCD31 further demonstrated that platelet aggregates were located in the lumen of blood vessel and were also distributed intratumorally in the mice bearing PDPN⁺ tumors.

Conclusions

These data demonstrated that PDPN expression in the cancer cells is associated with high risk of thrombosis, leading to unfavorable overall survival of the mice. This study provides new insights into the functions of PDPN in cancer-associated thrombosis and in the pathophysiology of OSCC.

Inflammation and Progression of Cholangiocarcinoma: Role of Angiogenic and Lymphangiogenic Mechanisms

Cholangiocarcinoma (CCA), or cancer of the biliary epithelium is a relatively rare but aggressive form of biliary duct cancer which has a 5-year survival rate post metastasis of 2%. Although a number of risk factors are established for CCA growth and progression, a careful evaluation of the existing literature on CCA reveals that an inflammatory environment near the biliary tree is the most common causal link between the risk factors and the development of CCA. The fact that inflammation predisposes affected individuals to CCA is further bolstered by multiple observations where the presence and maintenance of an inflammatory microenvironment at the site of the primary tumor plays a significant role in the development and metastasis of CCA. In addition, mechanisms activating the tumor vasculature and enhancing angiogenesis and lymphangiogenesis significantly contribute to CCA aggressiveness and metastasis. This review aims to address the role of an inflammatory microenvironment-CCA crosstalk and will present the basic concepts, observations, and current perspectives from recent research studies in the field of tumor stroma of CCA.

Association of high PDPN expression with pulmonary metastasis of osteosarcoma and patient prognosis

Podoplanin (PDPN) is an important positive regulator of platelet aggregation and functions as a lymphatic endothelial marker. PDPN has been observed to be expressed in human tumor tissues and various cancer cell lines. In the present study, PDPN expression in patients with primary osteosarcoma was assessed at the mRNA and protein levels, and the associations between PDPN expression and pulmonary metastasis (PM) and prognosis were examined. Reverse transcription-quantitative PCR (RT-qPCR) analysis was used to detect the expression levels of PDPN in primary osteosarcoma tissues and paired normal bone tissues (n=20 pairs). In addition, immunohistochemical analysis of PDPN expression was performed in 168 paraffin-embedded osteosarcoma tissue specimens and 23 matched normal tissues. The RT-qPCR results revealed higher mRNA expression levels of PDPN in patients with PM compared with patients without PM. Further survival analyses identified Enneking stage and PM as two independent prognostic indicators. Finally, univariate analysis revealed that high PDPN protein expression was significantly associated with Enneking stage and PM in patients with osteosarcoma.

Podoplanin-Expressing Macrophages Promote Lymphangiogenesis and Lymphoinvasion in Breast Cancer

Among mammary tumor-infiltrating immune cells, the highest expression of podoplanin (PDPN) is found in a subset of tumor-associated macrophages (TAMs). We hereby demonstrate that PDPN is involved in the attachment of this TAM subset to lymphatic endothelial cells (LECs). Mechanistically, the binding of PDPN to LEC-derived galectin 8 (GAL8) in a glycosylation-dependent manner promotes the activation of pro-migratory integrin β1. When proximal to lymphatics, PDPN-expressing macrophages (PoEMs) stimulate local matrix remodeling and promote vessel growth and lymphoinvasion. Anti-integrin β1 blockade, macrophage-specific Pdpn knockout, or GAL8 inhibition impairs TAM adhesion to LECs, restraining lymphangiogenesis and reducing lymphatic cancer spread. In breast cancer patients, association of PoEMs with tumor lymphatic vessels correlates with incidences of lymph node and distant organ metastasis.

The role of extracellular matrix in mouse and human corneal neovascularization

Corneal neo-vascularization (CNV) is a highly prevalent medical condition which impairs visual acuity. The role of specific proteins in modulating CNV has been extensively reported, although no studies have described the entire human proteome in CNV corneas. In this paper, we performed a proteomic analysis of vascularized vs healthy corneal stroma, in a CNV mouse model and in CNV-affected patients, with a specific focus on extracellular matrix (ECM) proteins. We identified and quantified 2315 murine proteins, 691 human proteins and validated 5 proteins which are differentially expressed in vascularized samples and conserved in mice and humans: tenascin-C and fibronectin-1 were upregulated, while decorin, lumican and collagen-VI were downregulated in CNV samples. Interestingly, among CNV patients, those affected with Acanthamoeba keratitis showed the highest levels of fibronectin-1 and tenascin-C, suggesting a specific role of these two proteins in Acanthamoeba driven corneal CNV. On a broader picture, our findings support the hypothesis that the corneal stroma in CNV samples is disorganized and less compact. We are confident that the dissection of the human corneal proteome may shed new light on the complex pathophysiology of human CNV, and finally lead to improved treatments.

Specific immune cell and lymphatic vessel signatures identified by image analysis in renal cancer

Anti-angiogenic therapy and immune checkpoint inhibition are novel treatment strategies for patients with renal cell carcinoma. Various components and structures of the tumor microenvironment are potential predictive biomarkers and also attractive treatment targets. Macrophages, tumor infiltrating lymphocytes, vascular and lymphatic vessels represent an important part of the tumor immune environment, but their functional phenotypes and relevance for clinical outcome are yet ill defined. We applied Tissue Phenomics methods including image analysis for the standardized quantification of specific components and structures within the tumor microenvironment to profile tissue sections from 56 clear cell renal cell carcinoma patients. A characteristic composition and unique spatial relationship of CD68+ macrophages and tumor infiltrating lymphocytes correlated with overall survival. An inverse relationship was found between vascular (CD34) and lymphatic vessel (LYVE1) density. In addition, outcome was significantly better in patients with high blood vessel density in the tumors, whereas increased lymphatic vessel density in the tumors was associated with worse outcome. The Tissue Phenomics imaging analysis approach allowed visualization and simultaneous quantification of immune environment components, adding novel contextual information, and biological insights with potential applications in treatment response prediction.

Comparing progression molecular mechanisms between lung adenocarcinoma and lung squamous cell carcinoma based on genetic and epigenetic networks: big data mining and genome-wide systems identification

Non-small-cell lung cancer (NSCLC) is the predominant type of lung cancer in the world. Lung adenocarcinoma (LADC) and lung squamous cell carcinoma (LSCC) are subtypes of NSCLC. We usually regard them as different disease due to their unique molecular characteristics, distinct cells of origin and dissimilar clinical response. However, the differences of genetic and epigenetic progression mechanism between LADC and LSCC are complicated to analyze. Therefore, we applied systems biology approaches and big databases mining to construct genetic and epigenetic networks (GENs) with next-generation sequencing data of LADC and LSCC. In order to obtain the real GENs, system identification and system order detection are conducted on gene regulatory networks (GRNs) and protein-protein interaction networks (PPINs) for each stage of LADC and LSCC. The core GENs were extracted via principal network projection (PNP). Based on the ranking of projection values, we got the core pathways in respect of KEGG pathway. Compared with the core pathways, we found significant differences between microenvironments, dysregulations of miRNAs, epigenetic modifications on certain signaling transduction proteins and target genes in each stage of LADC and LSCC. Finally, we proposed six genetic and epigenetic multiple-molecule drugs to target essential biomarkers in each progression stage of LADC and LSCC, respectively.

The stem cell markers expression CD44v6 and podoplanin in lip cancer: clinical significance

This study aimed to analyze the immunoexpression of cancer stem cell markers, CD44v6, and podoplanin in 91 patients with lip squamous cell carcinomas (LSCC). The immunostaining of podoplanin and CD44v6 was evaluated in ten high-power fields (× 400 magnification) at the invasive front of LSCC, using a semi-quantitative score method. Chi-square test or Fisher's exact test was used to verify the association of podoplanin and CD44v6 expressions with clinicopathologic variables. Spearman's correlation test was used to analyze the correlation between the two antibodies in lip cancer. Disease-free survival probabilities in 5 and 10 years were estimated according to the Kaplan-Meier method and compared using the log-rank test. The independent effects of the significant variables were analyzed by Cox proportional hazards regression model. A strong podoplanin expression was observed in the membrane and cytoplasm of most lip tumor cells, and this was inversely associated with locoregional recurrence (p = 0.028) and with histopathological grade of malignancy (p = 0.026). Additionally, CD44v6 immunostaining was strongly expressed in the membrane of tumor cells in 95.4% of the LSCC. Patients with strong membranous (p = 0.016) or strong cytoplasmic (p = 0.030) podoplanin-positive tumors resulted in significantly better disease-free survival than those who had podoplanin weak/negative tumors, confirming podoplanin expression as a favorable independent prognostic factor. Podoplanin and CD44v6 were strongly expressed by tumor cells and podoplanin immunoexpression can help to determine lip cancer patients with lower risk for disease recurrence.

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 (PDPN) affects the invasiveness of thyroid carcinoma cells by inducing ezrin, radixin and moesin (E/R/M) phosphorylation in association with matrix metalloproteinases

Background

Podoplanin (PDPN) is a mucin-type transmembrane glycoprotein specific to the lymphatic system. PDPN expression has been found in various human tumors and is considered to be a marker of cancer. We had previously shown that PDPN expression contributes to carcinogenesis in the TPC1 papillary thyroid cancer-derived cell line by enhancing cell migration and invasiveness. The aim of this study was to determine the effect of PDPN down-regulation in another thyroid cancer-derived cell line: BcPAP.

Methods

In order to determine the effects of PDPN on malignant features of BcPAP cells (harboring the BRAFV600E mutated allele) and TPC1 cells (carrying the RET/PTC1 rearrangement), we silenced PDPN in these cells using small interfering RNA (siRNA). The efficacy of PDPN silencing was confirmed by qRT-PCR and Western blotting. Then, we tested the motility and invasiveness of these cells (using scratch test and Transwell assay), their growth capacities F(cell cycle analysis, viability, clonogenic activity) and apoptosis assays), adhesion-independent colony-formation capacities, as well as the effect of PDPN silencing on MMPs expression and activity (zymography).

Results

We found that PDPN-induced cell phenotype depended on the genetic background of thyroid tumor cells. PDPN down-regulation in BcPAP cells was negatively correlated with the migration and invasion, in contrast to TPC1 cells in which PDPN depletion resulted in enhanced migration and invasiveness. Moreover, our results suggest that in BcPAP cells, PDPN may be involved in the epithelial-mesenchymal transition (EMT) through regulating the expression of the ezrin, radixin and moesin (E/R/M) proteins, MMPs 9 and MMP2, remodeling of actin cytoskeleton and cellular protrusions. We also demonstrated that PDPN expression is associated with the MAPK signaling pathway. The inhibition of the MAPK pathway resulted in a decreased PDPN expression, increased E/R/M phosphorylation and reduced cell migration. Additionally, PDPN depleted BcPAP cells treated with inhibitors of MEK1/2 kinases (U0126) or of the BRAF V600E protein (PLX4720) had reduced motility, similar to that previously observed in TPC1 cells after PDPN knock-down.

Conclusions

Altogether, our data suggest that PDPN may play an important role in the control of invasion and migration of papillary thyroid carcinoma cells in association with the E/R/M, MMPs and MAPK kinases.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5239-z) contains supplementary material, which is available to authorized users.

LpMab-23-recognizing cancer-type podoplanin is a novel predictor for a poor prognosis of early stage tongue cancer

Purpose

We report that the reactivity of a novel monoclonal antibody LpMab-23 for human cancer-type podoplanin (PDPN) is a predictor for a poor prognosis of tongue cancer.

Patients and Methods

The association between LpMab-23-recognizing cancer-type PDPN expression and clinical/pathological features were analyzed on 60 patients with stage I and II tongue cancer treated with transoral resection of the primary tumor.

Results

In the mode of invasion, the LpMab-23-dull/negative cases were significantly larger in cases with low-grade malignancies and without late cervical lymph node metastasis, than in cases with high-grade malignancies and the metastasis. In the high-grade malignant cases, LpMab-23-positive cases were significantly larger than LpMab-23-dull/negative cases. The Kaplan–Meier curves of the five-year metastasis-free survival rate (MFS) were significantly lower in the LpMab-23 positive patients than in LpMab-23 dull/negative patients. The LpMab-23-dull/negative cases showed the highest MFS in all of the clinical/pathological features and particularly, the MFS of the LpMab-23 positive cases decreased to less than 60% in the first year. In the Cox proportional hazard regression models a comparison of the numbers of LpMab-23 dull/negative with positive cases showed the highest hazard ratio with statistical significance in all of the clinical/pathological features.

Conclusions

LpMab-23 positive cases may be considered to present a useful predictor of poor prognosis for early stage tongue cancer.

Tumor hypoxia modulates podoplanin/CCL21 interactions in CCR7+ NK cell recruitment and CCR7+ tumor cell mobilization

Podoplanin (PDPN), an O-glycosylated, transmembrane, mucin-type glycoprotein, is expressed by cancer associated fibroblasts (CAFs). In malignant transformation, PDPN is subjected to changes and its role is yet to be established. Here we show that it is involved in modulating the activity of the CCL21/CCR7 chemokine/receptor axis in a hypoxia-dependent manner. In the present model, breast cancer MDA-MB-231 cells and NKL3 cells express the surface CCR7 receptor for CCL21 chemokine which is a potent chemoattractant able to bind to PDPN. The impact of the CCL21/CCR7 axis in the molecular mechanism of the adhesion of NKL3 cells and of MDA-MB-231 breast cancer cells was reduced in a hypoxic tumor environment. In addition to its known effect on migration, CCL21/CCR7 interaction was shown to allow NK cell adhesion to endothelial cells (ECs) and its reduction by hypoxia. A PDPN expressing model of CAFs made it possible to demonstrate the same CCL21/CCR7 axis involvement in the tumor cells to CAFs recognition mechanism through PDPN binding of CCL21. PDPN was induced by hypoxia and its overexpression undergoes a reduction of adhesion, making it an anti-adhesion molecule in the absence of CCL21, in the tumor. CCL21/CCR7 modulated NK cells/ECs and MDA-MB-231 cells/CAF PDPN-dependent interactions were further shown to be linked to hypoxia-dependent microRNAs as miRs: miR-210 and specifically miR-21, miR-29b which influence PDPN expression.

Podoplanin regulates mammary stem cell function and tumorigenesis by potentiating Wnt/β-catenin signaling

Stem cells (SCs) drive mammary development, giving rise postnatally to an epithelial bilayer composed of luminal and basal myoepithelial cells. Dysregulation of SCs is thought to be at the origin of certain breast cancers; however, the molecular identity of SCs and the factors regulating their function remain poorly defined. We identified the transmembrane protein podoplanin (Pdpn) as a specific marker of the basal compartment, including multipotent SCs, and found Pdpn localized at the basal-luminal interface. Embryonic deletion of Pdpn targeted to basal cells diminished basal and luminal SC activity and affected the expression of several Wnt/β-catenin signaling components in basal cells. Moreover, Pdpn loss attenuated mammary tumor formation in a mouse model of β-catenin-induced breast cancer, limiting tumor-initiating cell expansion and promoting molecular features associated with mesenchymal-to-epithelial cell transition. In line with the loss-of-function data, we demonstrated that mechanistically Pdpn enhances Wnt/β-catenin signaling in mammary basal cells. Overall, this study uncovers a role for Pdpn in mammary SC function and, importantly, identifies Pdpn as a new regulator of Wnt/β-catenin signaling, a key pathway in mammary development and tumorigenesis.

Podoplanin emerges as a functionally relevant oral cancer biomarker and therapeutic target

Oral cancer has become one of the most aggressive types of cancer, killing 140,000 people worldwide every year. Current treatments for oral cancer include surgery and radiation therapies. These procedures can be very effective; however, they can also drastically decrease the quality of life for survivors. New chemotherapeutic treatments are needed to more effectively combat oral cancer. The transmembrane receptor podoplanin (PDPN) has emerged as a functionally relevant oral cancer biomarker and chemotherapeutic target. PDPN expression promotes tumor cell migration leading to oral cancer invasion and metastasis. Here, we describe the role of PDPN in oral squamous cell carcinoma progression, and how it may be exploited to prevent and treat oral cancer.

Moesin expression by tumor cells is an unfavorable prognostic biomarker for oral cancer

Background

Moesin is a member of the ERM (ezrin, radixin and moesin) proteins that participate in cell migration and tumor invasion through transductional signals sent to actin filaments by glycoproteins, such as podoplanin.

Methods

This study aimed to evaluate the participation of moesin and podoplanin in the invasive tumor front of oral squamous cell carcinomas, and their influence on patients’ prognosis. Podoplanin and moesin immunoexpressions were evaluated by a semi-quantitative score method, based on the capture of 10 microscopic fields, at 400X magnification, in the invasive tumor front of oral squamous cell carcinomas. The association of moesin and podoplanin expression with clinicopathological variables was analyzed by the chi-square, or Fisher’s exact test. The 5 and 10 years survival rates were calculated by the Kaplan-Meier method and the survival curves were compared by using the log-rank test.

Results

The immunohistochemical expression of moesin in the invasive front of oral squamous cell carcinomas was predominantly strong, homogenously distributed on the membrane and in the cytoplasm of tumor cells. The expression of moesin was not associated with clinical, demographic and microscopic features of the patients. Otherwise, podoplanin expression by malignant epithelial cells was predominantly strong and significantly associated with radiotherapy (p = 0.004), muscular invasion (p = 0.006) and lymph node involvement (p = 0.013). Strong moesin expression was considered an unfavorable prognostic factor for patients with oral squamous cell carcinomas, clinical stage II and III (p = 0.024).

Conclusions

These results suggested that strong moesin expression by malignant cells may help to determine patients with oral squamous cell carcinoma and poor prognosis.

Tumor vascularization and clinicopathologic parameters as prognostic factors in merkel cell carcinoma

PURPOSE

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine tumor of the skin with an increasing incidence. The clinical course is variable and reliable prognostic factors are scarce. Tumor angiogenesis has been shown to have prognostic impact in different types of cancer. The aim of our study was to determine potential prognostic factors, including tumor vascularization, for clinical outcome of MCC.

METHODS

The medical records of 46 patients with MCC diagnosed between 1997 and 2010 were analyzed retrospectively. Tissue samples were immune-stained for the lymphatic endothelial vessel marker podoplanin/D2-40 and the panvascular marker CD31. These immunostained sections were analyzed using computer-assisted morphometric image analyses. Aside from the parameters of tumor vascularization, clinicopathologic features were investigated, and progression-free survival (PFS) and tumor-specific survival (TSS) were assessed. Univariate and multivariate analyses were performed to determine prognostic factors.

RESULTS

Male sex of the MCC patients and a high cross-sectional whole vessel area (WVA) in relation to the entire tumor area as determined on CD31-stained tumor sections were found to be negative prognostic factors for PFS in a univariate and multivariate regression analysis. Ulceration of the primary tumor was significantly associated with both impaired PFS and TSS.

CONCLUSIONS

Our results indicate a high prognostic impact of tumor vascularization on the clinical outcome of MCC patients. Male sex and ulceration of the primary MCC were identified as independent unfavorable prognostic markers for the clinical outcome. As an outlook, MCC patients with increased angiogenesis might be identified and subjected to a targeted anti-angiogenic treatment.

Co-expression of podoplanin and fibroblast growth factor 1 predicts poor prognosis in patients with lung squamous cell carcinoma

Podoplanin and fibroblast growth factor (FGF) 1 have been detected more frequently in lung squamous cell carcinoma (SQCC) compared with lung adenocarcinoma. Furthermore, it has been previous demonstrated that FGF1 is located on the edge of tumor nests in certain lung SQCC sections, which resembles the characteristic expression pattern of podoplanin. Podoplanin and FGF1 have roles in lymphangiogenesis and angiogenesis. Based on their consistently specific expression in lung SQCC and similar localization patterns, the present study aimed to investigate whether the expression of podoplanin in tumor cells is correlated with FGF1 expression in lung SQCC and whether their co-expression has clinicopathological significance, particularly for lymphangiogenesis/angiogenesis. The correlation between podoplanin and FGF1 expression in tumor cells of 82 lung SQCC cases was investigated by immunohistochemical staining and the association between the co-expression of podoplanin and FGF1, and clinicopathological factors such as microvessel density (MVD), was examined in these samples. In addition, the prognostic value of co-expression of podoplanin and FGF1 in tumor cells was determined, and the regulation of FGF1 expression and angiogenesis by podoplanin was examined in vitro in a human lung SQCC cell line. Immunohistochemical analysis demonstrated that there was a significant correlation between podoplanin and FGF1 expression in lung SQCC tumor cells (R=0.591; P<0.0001). Co-expression of podoplanin and FGF1 was significantly associated with larger primary tumor size, advanced TNM stage and higher intratumoral MVD. Survival analysis demonstrated that cases with podoplanin and FGF1 double-positive staining had a significantly lower survival rate compared with cases with double-negative staining. In vitro experiments revealed that podoplanin regulated FGF1 expression and affected tube formation of human umbilical vein endothelial cells. Combined, the results demonstrated that podoplanin was co-expressed with FGF1 in lung SQCC and this co-expression was correlated with poor prognosis.

For robust big data analyses: a collection of 150 important pro-metastatic genes

Metastasis is the greatest contributor to cancer-related death. In the era of precision medicine, it is essential to predict and to prevent the spread of cancer cells to significantly improve patient survival. Thanks to the application of a variety of high-throughput technologies, accumulating big data enables researchers and clinicians to identify aggressive tumors as well as patients with a high risk of cancer metastasis. However, there have been few large-scale gene collection studies to enable metastasis-related analyses. In the last several years, emerging efforts have identified pro-metastatic genes in a variety of cancers, providing us the ability to generate a pro-metastatic gene cluster for big data analyses. We carefully selected 285 genes with in vivo evidence of promoting metastasis reported in the literature. These genes have been investigated in different tumor types. We used two datasets downloaded from The Cancer Genome Atlas database, specifically, datasets of clear cell renal cell carcinoma and hepatocellular carcinoma, for validation tests, and excluded any genes for which elevated expression level correlated with longer overall survival in any of the datasets. Ultimately, 150 pro-metastatic genes remained in our analyses. We believe this collection of pro-metastatic genes will be helpful for big data analyses, and eventually will accelerate anti-metastasis research and clinical intervention.

Identification of a novel platelet antagonist that binds to CLEC-2 and suppresses podoplanin-induced platelet aggregation and cancer metastasis

Podoplanin (PDPN) enhances tumor metastases by eliciting tumor cell-induced platelet aggregation (TCIPA) through activation of platelet C-type lectin-like receptor 2 (CLEC-2). A novel and non-cytotoxic 5-nitrobenzoate compound 2CP was synthesized that specifically inhibited the PDPN/CLEC-2 interaction and TCIPA with no effect on platelet aggregation stimulated by other platelet agonists. 2CP possessed anti-cancer metastatic activity in vivo and augmented the therapeutic efficacy of cisplatin in the experimental animal model without causing a bleeding risk. Analysis of the molecular action of 2CP further revealed that Akt1/PDK1 and PKCμ were two alternative CLEC-2 signaling pathways mediating PDPN-induced platelet activation. 2CP directly bound to CLEC-2 and, by competing with the same binding pocket of PDPN in CLEC-2, inhibited PDPN-mediated platelet activation. This study provides evidence that 2CP is the first defined platelet antagonist with CLEC-2 binding activity. The augmentation in the therapeutic efficacy of cisplatin by 2CP suggests that a combination of a chemotherapeutic agent and a drug with anti-TCIPA activity such as 2CP may prove clinically effective.

Podoplanin, ezrin, and Rho-A proteins may have joint participation in tumor invasion of lip cancer

INTRODUCTION

Podoplanin and ezrin connection through Rho-A phosphorylation have been suggested as part of the activation pathway, in the process of tumor invasion and cell movement in oral squamous cell carcinomas.

OBJECTIVE

The aim of this study was to evaluate the correlation among podoplanin, ezrin, and Rho-A immunoexpressions in 91 squamous cells carcinomas of the lower lip and their influence in patient's prognosis.

MATERIAL AND METHODS

The immunoexpressions of podoplanin, ezrin, and Rho-A were evaluated through a semi-quantitative score method, based on the capture of 10 microscopic fields at the front of tumor invasion. The association and correlation of these proteins with the clinicopathological features were verified by Fischer's exact test and Spearman's test. The prognostic values were analyzed by Kaplan-Meier method and log-rank test.

RESULTS

A statistically significant association between strong cytoplasmic podoplanin expression and alcohol (p = 0.024), loco-regional recurrences (p = 0.028), and lymph node metastasis (pN+) (p = 0.010) was found. The membranous (p = 0.000 and r = 0.384) and cytoplasmic (p = 0.000 and r = 0.344) podoplanin expression was statistically correlated with ezrin expression. Also, membranous podoplanin was significantly correlated with Rho-A expression (p = 0.006 and r = 0.282). The expressions of podoplanin, ezrin, and Rho-A were not significant prognostic factors for patients with squamous cell carcinomas of the lower lip.

CONCLUSIONS

Therefore, our results confirm a correlation among podoplanin, ezrin, and Rho-A expressions in squamous cell carcinoma of the lip suggesting a cooperative participation of these proteins in cell movement and invasion.

CLINICAL RELEVANCE

Furthermore, strong cytoplasmic podoplanin expression could be helpful to identify patients with squamous cell carcinoma of the lip and lower risk of loco-regional recurrences.

Correlation between podoplanin expression and extracapsular spread in squamous cell carcinoma of the oral cavity using subjective immunoreactivity scores and semiquantitative image analysis

BACKGROUND

The correlation between podoplanin expression and extracapsular spread in head and neck squamous cell carcinoma (HNSCC) has never been reported. The purpose of this study was to assess the predictive value of podoplanin expression for this parameter.

METHODS

Subjective immunoreactivity scores and semiquantitative image analysis of podoplanin expression were performed in 67 patients with primary oral squamous cell carcinoma and in their corresponding lymph nodes. Neck classification showed 34 cases (51%) of pN0 and 33 cases (49%) of pN+. Correlation between the levels of podoplanin expression and the histopathological data was established.

RESULTS

In lymph nodes, a high level of podoplanin expression correlated with the presence of extracapsular spread by multivariate analysis (p = .03). A strong correlation between subjective and semiquantitative image analysis was observed (r = 0.77; p < .001).

CONCLUSION

A high level of podoplanin expression in lymph node metastases of oral squamous cell carcinoma is independently associated with extracapsular spread. © 2016 Wiley Periodicals, Head Neck 39: 98-108, 2017.

Prognostic significance of CD44v6, p63, podoplanin and MMP-9 in oral squamous cell carcinomas

OBJECTIVES

To analyse the expression of the CD44v6, p63, podoplanin and MMP-9, and their prognostic significance in patients with oral squamous cell carcinomas (OSCC).

MATERIAL AND METHODS

Immunohistochemistry technique was performed on 60 OSCC for detection of CD44v6, p63, podoplanin and MMP-9 proteins. Extent and intensity of staining were evaluated in tumour cells and were compared with patients' clinical-pathological characteristics and survival.

RESULTS

CD44v6 expression was detected at the membrane of tumour cells of 94% cases. Nuclear expression of p63 protein was present in 96.5%. Podoplanin was observed at the membrane of tumour cells of 94% cases. MMP-9 was found in the cytoplasm of tumour cells in 83.7% cases. A high level of expression (67%-89%) in all four proteins was noted. Podoplanin was associated with the expression of MMP-9 (P = 0.010) and both were associated with lymph node metastasis (P = 0.011 and P = 0.018, respectively). Co-expression of podoplanin/MMP-9 was an adverse independent prognostic factor for cancer-specific survival (P = 0.008) and recurrence-free survival (P = 0.042).

CONCLUSION

Podoplanin and MMP-9 together could contribute to tumour progression and dissemination of OSCC. Their combined overexpression showed an adverse effect on survival, suggesting that they could be regarded as important prognostic biomarkers in OSCC.

Podoplanin - a small glycoprotein with many faces

Podoplanin is a small membrane glycoprotein with a large number of O-glycoside chains and therefore it belongs to mucin-type proteins. It can be found on the surface of many types of normal cells originating from various germ layers. It is present primarily on the endothelium of lymphatic vessels, type I pneumocytes and glomerular podocytes. Increased levels of podoplanin or its neo-expression have been found in numerous types of human carcinomas, but it is especially common in squamous cell carcinomas, such as cervical, larynx, oral cavity, skin and lung cancer. This small sialomucin is also seen on the surface of cancer-associated fibroblasts (CAFs) in lung adenocarcinomas, as well as in breast and pancreatic tumors. In most cancers, a high level of podoplanin expression, both in cancer cells, as well as in CAFs, is correlated with an increased incidence of metastasis to lymph nodes and shorter survival time of patients. Little is known about the biological role of podoplanin, however research carried out on mice with a knock-out gene of this glycoprotein shows that the presence of podoplanin determines normal development of lungs, the lymphatic system and heart. Podoplanin on cancer cells and CAFs seems to play an important role in the development and progression of various cancers. However, its role in these processes is both unclear and controversial. In this review, the role of podoplanin in both physiological processes and carcinogenesis is discussed.

Phosphorylated mTOR expression correlates with podoplanin expression and high tumor grade in esophageal squamous cell carcinoma

Mechanistic (or mammalian) target of rapamycin (mTOR) plays important roles in cell growth and proliferation. In esophageal squamous cell carcinoma (SCC), high expression of phosphorylated (activated) mTOR (p-mTOR) has been reported as an adverse prognostic factor in some but not all studies. The signals of mTOR pathway and mitogen-activated protein kinase (MAPK) pathway converge on 4E-binding protein 1 (4EBP1), which drives the downstream proliferative signals. We previously found that high expression of phosphorylated 4EBP1 (p-4EBP1) is an adverse prognostic factor in esophageal SCC. Podoplanin is a type-1 transmembrane glycoprotein expressed in various normal human tissues, including lymphatic endothelium. Our previous study showed that high podoplanin expression correlates with clinical nodal metastasis, which is associated with short survival in esophageal SCC. In current study, we investigated p-mTOR expression by immunohistochemistry in 75 cases of surgically resected esophageal SCC. The result was correlated with p-4EBP1 expression, podoplanin expression, clinicopathologic features and patient survival. We found that high p-mTOR expression was significantly associated with high podoplanin expression (P = 0.0030) and high tumor grade (P = 0.0014). No correlation with p-4EBP1 expression, patient survival or other clinicopathologic features was found. Recently, podoplanin expression in astrocytic brain tumors was found to be regulated by the phosphatidylinositol 3-kinase (PI3K)/AKT/activator protein-1 (AP-1) pathway. Similarly, mTOR is activated by a PI3K/AKT/mTOR pathway. The association of p-mTOR and podoplanin expression in our study could be due to a common upstream pathway. Since both mTOR and podoplanin are potential therapeutic targets, the possible benefit of combined targeted therapy warrants further investigation.