Vasculogenic Mimicry in Head and Neck Squamous Cell Carcinoma—Time to Take Notice

Head and neck squamous cell carcinoma (HNSCC) is a group of common cancers characterized by a swift growth pattern, early metastasis, and dismal 5-year survival rates. Despite the recent advances in cancer management, the multimodality approach is not effective in eradicating HNSCC. Moreover, the clinical response to the antiangiogenic therapy remains considerably limited in HNSCC patients, suggesting that tumour perfusion can take place through other non-angiogenic pathways. Tumour cell-induced angiogenesis is one of the main hallmarks of cancer. However, at the end of the previous millennium, a new paradigm of tumour cell-associated neovascularization has been reported in human melanoma cells. This new phenomenon, which was named “vasculogenic mimicry” or “vascular mimicry” (VM), describes the ability of aggressively growing tumour cells to form perfusable, matrix-rich, vessel-like networks in 3-dimenstional matrices in vitro. Similar matrix-rich VM networks were also identified in tissue samples obtained from cancer patients. To date, myriad studies have reported intriguing features of VM in a wide variety of cancers including HNSCC. We aim in this mini-review to summarize the current evidence regarding the phenomenon of VM in HNSCC—from the available detection protocols and potentially involved mechanisms, to its prognostic value and the present limitations.Peer reviewe

Commentary: Pathophysiological Role of Histamine H4 Receptor in Cancer: Therapeutic Implications

Peer reviewe

Histamine H4 Receptor : A Potential Novel Therapeutic Target in Oral Lichen Planus and Oral Tongue Cancer

Background and objective: Oral lichen planus (OLP) is a common immune disorder of the oral mucosa, which is categorized as an oral potentially malignant disorder (OPMD) to highlight its potential progression to oral cancer. Oral cancer commonly affects the mobile tongue as oral tongue squamous cell carcinoma (OTSCC), which has dismal prognosis. Histamine signals via four G protein-coupled histamine receptors (H1R-H4R). Classical H1R and H2R medications are ineffective in treating OLP or OTSCC patients. The discovery of H4R has paved the way for novel perspectives in histamine research by modulating immune responses. We therefore hypothesized that H4R is involved in the pathogenesis of OLP and may contribute to oral carcinogenesis. Materials and methods: Tissue samples from OLP, oral epithelial dysplasia (OED) and OTSCC patients, and from healthy control participants were utilized. The in vitro experiments were performed on normal human oral keratinocytes (HOKs), two OTSCC-derived cell lines (HSC-3 and SCC-25), normal salivary gland cells, in addition to supernatants from activated human mast cells (MCs). For in vitro internalization and functional assays, two specific H4R ligands (agonist HST-10, and inverse agonist ST-1007) were used. Protein expression of histamine receptors, transporters and metabolizing enzymes, and other antigens were assessed in tissue samples and cell lines by immunohistochemistry and immunofluorescence staining. The expression levels of mRNA were quantified by qRT-PCR and the highly-sensitive droplet-digital PCR technology. Western blotting assays were performed to assess apoptotic markers following H4R stimulation, while flow cytometry was used to study Annexin-V and PI labelling of dead cells. Histamine levels were analysed using high-performance liquid chromatography. Results: Briefly, H4R is expressed in healthy oral epithelial cells on mRNA and protein levels, and they were able to fully internalize H4R-ligands in a time-dependent manner. In contrast, samples from OLP, OED and OTSCC patients exhibited lower H4R level, which was negatively correlated with MC-count and OTSCC-grade. We also reported that normal HOKs are histamine-producing cells—fully equipped with histamine synthesizing, transporting and degrading molecules. Interestingly, OLP samples exhibit high levels of the histamine synthesizing and transporting molecules, whereas histamine degrading enzyme was strongly inhibited. HOKs showed a dose-dependent Lipopolysaccharides (LPS)-driven release of histamine, while high histamine levels inhibited epithelial adhesion molecules. We next showed that toll-like receptors (TLRs) are essential players in OLP. TLRs were upregulated in OLP lesions, particularly for TLR4, which is necessary for LPS signalling. Importantly, LPS and MC-mediators regulated several oral oncogenes, while H4R-stimulated cells revealed a marked resistance to apoptosis. Furthermore, LPS and histamine influenced human beta defensin 2 (hBD-2) expression, which was highly induced in OLP. Unexpectedly, hBD-2 protein was subsided in OTSCC tissues with a marked downregulation of its transcript in cancer cells. Histamine synergistically induced TNF-α- and IFN-γ-mediated hBD-2 production in HOKs. Interestingly, targeting H4R seems to regulate TNFα- and LPS-mediated expression of hBD-2. Conclusions: Briefly, human oral epithelial cells are “non-professional” histamine producing cells—capable to synthesize, release, and degrade low levels of endogenic histamine. High levels of histamine may downregulate H4R as well as key integrity molecules in HOKs and may enhance subsequent bacterial invasion in OLP. In this regard, our findings suggest a potential role of TLRs in OLP pathogenesis, by mediating LPS signalling and enhancing further immune response and histamine production. In addition, our results indicate that histamine/H4R crosstalk signalling with LPS and MCs could in part be involved in OLP and the potential inflammation-driven tumorigenesis. This was further supported by the ability of H4R to regulate cell apoptosis and modulate antibacterial response in HOKs. Further functional and preclinical studies are therefore warranted.Punajäkälä on tavallinen suun limakalvolla esiintyvä tulehdustauti, joka aiheutuu elimistön immuunijärjestelmän häiriöstä. Perinteiset antihistamiinit ovat osoittautuneet tehottomiksi punajäkälän hoidossa, mutta histamiini 4 -reseptorin (H4R) löytyminen on avannut uusia tutkimusmahdollisuuksia aiheesta. Tämän työn hypoteesina oli, että H4R saattaisi vaikuttaa sekä punajäkälän että kielisyövän syntymiseen. Työn ensimmäisessä vaiheessa osoitimme, että terveet suun limakalvon epiteelisolut ilmensivät H4-reseptoria voimakkaammin verrattuna punajäkälän vaurioittamiin kudosnäytteisiin. Näistä näytteistä löysimme sen sijaan suuria määriä histamiinin tuottamiseen ja kuljettamiseen liittyviä molekyylejä ja vain vähän histamiinia hajottavaa entsyymiä. Tässä yhteydessä pystyimme todentamaan limakalvon keratinosyyttien itsessään toimivan histamiinia tuottavina soluina. Lipopolysakkaridit (LPS) kiihdyttivät histamiinin vapautumista näistä soluista, mutta korkeat histamiinipitoisuudet heikensivät epiteelisolujen kiinnittymisrakenteiden toimintaa. Tutkimuksen seuraavassa vaiheessa havaitsimme Tollin kaltaisten reseptoreiden (TLR) yhdistyvän keskeisesti punajäkälän taudinkuvaan, sillä näiden esiintyminen oli korostunut punajäkälälle altistuneella limakalvolla. Pystyimme myös todentamaan, että LPS ja syöttösolujen tulehdusvälittäjät säätelivät useita epiteelisolujen syöpägeenejä H4R:n osallistuessa näiden apoptoosin säätelyyn. Tämän lisäksi LPS ja histamiini vaikuttivat defensiinien ilmentymiseen limakalvon pintasolukossa. Epiteelisolut pystyivät siis tuottamaan ja hajottamaan histamiinia, joka suurina pitoisuuksina laski histamiini 4-resetorin ja lisäsi bakteerirakenteiden esiintymistä suun punajäkälässä. Tutkimuksemme mukaan H4R vaikuttaa lupaavalta kohteelta, jonka toimintaan vaikuttamalla voitaisiin auttaa punajäkälän ja suusyövän hoidossa. Tarkentavat jatkotutkimukset aiheesta ovat näin ollen perusteltuja

Role of Cyclooxygenase-2 in Head and Neck Tumorigenesis

The cyclooxygenase-2 (COX-2) is a potent enzyme that converts arachidonic acid to prostaglandins (PG), including PGE2, a key mediator of inflammation and angiogenesis. Importantly, COX-2 is activated in response to inflammatory stimuli, where it is also believed to promote the development and progression of head and neck cancers (HNC). COX-2 can mediate its protumorigenic effect through various mechanisms, such as inducing cell proliferation, inhibition of apoptosis, and suppressing the host’s immune response. Furthermore, COX-2 can induce the production of vascular endothelial growth factors, hence, promoting angiogenesis. Indeed, the ability of COX-2 inhibitors to selectively restrict the proliferation of tumor cells and mediating apoptosis provides promising therapeutic targets for cancer patients. Thus, in this comprehensive review, we summarized the reported differential expression patterns of COX-2 in different stages of head and neck carcinogenesis—from potentially premalignant lesions to invasive carcinomas. Furthermore, we examined the available meta-analysis evidence for COX-2 role in the carcinogenesis of HNC. Finally, further understanding of the biological processes of COX-2 and its role in orchestrating cell proliferation, apoptosis, and angiogenesis may give therapeutically beneficial insight to develop the management plan of HNC patients and improve their clinical outcomes

Oral Microbiota—A New Frontier in the Pathogenesis and Management of Head and Neck Cancers

Head and neck squamous cell carcinoma (HNSCC) comprises the majority of tumors in head and neck tissues. The prognosis of HNSCC has not significantly improved for decades, signifying the need for new diagnostic and therapeutic targets. Recent evidence suggests that oral microbiota is associated with carcinogenesis. Thus, we conducted a comprehensive systematic review to evaluate the current evidence regarding the role of oral microbiota in HNSCC and whether their targeting may confer diagnostic, prognostic or therapeutic utility. Following the screening of 233 publications retrieved from multiple databases, 34 eligible studies comprising 2469 patients were compiled and critically appraised. Importantly, many oral pathogens, such as Porphyromonas gingivalis and Fusobacterium nucleatum were linked to certain oral potentially malignant lesions and various types of HNSCC. Furthermore, we summarized the association between the expression profiles of different oral bacterial species and their tumorigenic and prognostic effects in cancer patients. We also discussed the current limitations of this newly emerging area and the potential microbiota-related strategies for preventing and treating HNSCC. Whilst many clinical studies are underway to unravel the role of oral microbiota in cancer, the limited available data and experimental approaches reflect the newness of this promising yet challenging field

The Prognostic Influence of Lymphatic Endothelium-specific Hyaluronan Receptor 1 In Cancer—A Systematic Review

Lymphangiogenesis is a key process in cancer development and metastasis. Lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) is a widely used marker for lymphatic endothelial cells (LEC), which also mediates immune and cancer cell migration. Recently, LYVE-1-positive tumor cells were shown to acquire LEC-like phenotype and exploit this receptor for lymphatic dissemination. Furthermore, selective targeting of LYVE-1 impaired the growth of cancer-related vasculature and reduced metastasis in vivo, signifying its role in therapeutic and prognostic applications. Although numerous studies have investigated the role of LYVE-1 in cancer, a unifying detailed review of its prognostic utility is lacking to date. Thus, we compiled and critically appraised evidence from clinical studies comprising a total of 2352 patients diagnosed with different types of cancer and using a variety of experimental approaches. Collectively, most studies revealed a significant association between LYVE-1 overexpression and dismal outcome of at least one survival estimate. Furthermore, the importance of vasculature location, intra- or peritumoral, and the influence of various lymphangiogenesis-related parameters, such as lymphatic vessel density and invasion, were discussed. However, the specificity of LYVE-1 staining is challenged by its expression in non-LEC cells, implying the need for double labelling to better estimate its prognostic significance. In conclusion, this is to our knowledge the first comprehensive systematic review on the prognostic value of LYVE-1 in cancer. More well-designed studies across different populations and the development of standardized protocols would be paramount for the consistency of LYVE-1 findings and for its potential transferability to clinical practice in future.Peer reviewe

Oral Microbiota—A New Frontier in the Pathogenesis and Management of Head and Neck Cancers

Head and neck squamous cell carcinoma (HNSCC) comprises the majority of tumors in head and neck tissues. The prognosis of HNSCC has not significantly improved for decades, signifying the need for new diagnostic and therapeutic targets. Recent evidence suggests that oral microbiota is associated with carcinogenesis. Thus, we conducted a comprehensive systematic review to evaluate the current evidence regarding the role of oral microbiota in HNSCC and whether their targeting may confer diagnostic, prognostic or therapeutic utility. Following the screening of 233 publications retrieved from multiple databases, 34 eligible studies comprising 2469 patients were compiled and critically appraised. Importantly, many oral pathogens, such as Porphyromonas gingivalis and Fusobacterium nucleatum were linked to certain oral potentially malignant lesions and various types of HNSCC. Furthermore, we summarized the association between the expression profiles of different oral bacterial species and their tumorigenic and prognostic effects in cancer patients. We also discussed the current limitations of this newly emerging area and the potential microbiota-related strategies for preventing and treating HNSCC. Whilst many clinical studies are underway to unravel the role of oral microbiota in cancer, the limited available data and experimental approaches reflect the newness of this promising yet challenging field

Editorial: Angiogenesis and Angiogenesis Inhibitors in Oral Cancer

Non peer reviewe

No detection of TSH or TSHR in oral lichen planus lesions in patients with or without hypothyroidism

Objective: An association between hypothyroidism (HT) and oral lichen planus (OLP) has been reported. However, the mechanisms that could explain this association remain unresolved. This study aimed to evaluate the expression of thyroid-stimulating hormone (TSH) and thyroid-stimulating hormone receptor (TSHR) in healthy oral mucosa and in OLP lesions of individuals with and without HT. Material and methods: Immunohistochemical expression of TSH and TSHR was studied in oral mucosal biopsies obtained from 14 OLP patients with HT, 14 OLP patients without HT and 10 healthy controls without oral mucosal lesions. Gene expression of TSHR was investigated by using three different PCR techniques in oral mucosal samples from 7 OLP patients with HT, 3 OLP patients without HT, 9 healthy controls and in cultured human oral epithelial cells. Gene expression of TSH was examined by employing 2 PCR techniques in oral mucosal samples from 2 OLP patients with HT, 2 OLP patients without HT and 4 healthy controls. Results: TSH and TSHR stainings were negative in the studied oral mucosal specimens. Gene quantification assays demonstrated negative gene expression of TSH and TSHR in clinical and in vitro samples. Conclusions: These results suggest that TSH and TSHR may not be commonly involved in the pathogenetic mechanism that could explain the association between OLP and hypothyroidism.Peer reviewe

The Prognostic Value of Toll-Like Receptors in Head and Neck Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

Head and neck squamous cell carcinoma (HNSCC) is a group of tumours which exhibit low 5 year survival rates. Thus, there is an urgent need to identify biomarkers that may improve the clinical utility of patients with HNSCC. Emerging studies support a role of toll-like receptors (TLRs) in carcinogenesis. Therefore, this systematic review and meta-analysis was performed to assess the prognostic value of TLR immunoexpression in HNSCC patients. We compiled the results of thirteen studies comprising 1825 patients, of which six studies were deemed qualified for quantitative synthesis. The higher immunoexpression of TLR-1 to 5 and 9 was associated with a worsening of the clinical parameters of patients with HNSCC. Furthermore, induced levels of TLR-3, 4, 5, 7 and 9 were found to predict the patients’ survival time. The meta-analysis revealed that TLR-7 overexpression is associated with a decreased mortality risk in HNSCC patients (HR 0.51; 95%CI 0.13–0.89; I2 34.6%), while a higher expression of TLR-5 predicted shorter, but non-significant, survival outcome. In conclusion, this review suggests that TLRs may represent some prognostic value for patients with HNSCC. However, due to small sample sizes and other inherent methodological limitations, more well designed studies across different populations are still needed before TLRs can be recommended as a reliable clinical risk-stratification tool