Vascular endothelial growth factor expression in head and neck squamous cell carcinoma

The effects of tumor-derived supernatants (TDS) on cancer cell progression: A review and update on carcinogenesis and immunotherapy

Tumors can produce bioactive substances called tumor-derived supernatants (TDS) that modify the immune response in the host body. This can result in immunosuppressive effects that promote the growth and spread of cancer. During tumorigenesis, the exudation of these substances can disrupt the function of immune sentinels in the host and reinforce the support for cancer cell growth. Tumor cells produce cytokines, growth factors, and proteins, which contribute to the progression of the tumor and the formation of premetastatic niches. By understanding how cancer cells influence the host immune system through the secretion of these factors, we can gain new insights into cancer diagnosis and therapy.

How to Treat Today? Oral and Facial Cancer-Associated Venous Thromboembolism

The exact incidence of cancer-associated venous thromboembolism (CA-VTE) in patients with oral and facial cancer (OFC) is not exactly known, and this risk is empirically considered to be low. However, this suggestion may result in disease underdiagnosis, prolong the initiation of adequate therapy, and consecutively increase CA-VTE-related morbidity and mortality. In addition, there might be specific clinical problems in the treatment of CA-VTE in patients with oral and facial cancer, such as swallowing difficulties, that might limit the possibilities of oral anticoagulation. Finally, there are limited data regarding the optimal treatment of CA-VTE in patients with oral and facial cancer, and this includes data on novel therapeutic strategies, including the use of direct oral anticoagulants. This article reviews current data on the optimal treatment strategy for CA-VTE in patients with OFC.

Oral Squamous Cell Carcinoma-Associated Thrombosis: What Evidence?

Venous thromboembolism (VTE) disease is the second leading cause of mortality in cancer patients. In the general population, the annual incidence of a thromboembolic event is about 117 cases per 100,000 persons, but cancer increases this risk about fourfold, while in patients receiving chemotherapy and surgical treatment, it is about sevenfold. Oral squamous cell carcinoma (OSCC) is the most common form of oral cancer and represents a multistep process in which environmental factors and genetic alterations are implicated. Thrombotic risk is considered empirically low in OSCC patients, although few data are available. Having limited information available may result in poor awareness of VTE prevention in OSCC, risking jeopardising the oncologic treatment and increasing the morbidity and mortality among these patients. In this paper, the topic of OSCC-associated thrombosis will be discussed.

MAPK Signaling Pathway in Oral Squamous Cell Carcinoma: Biological Function and Targeted Therapy

Oral squamous cell carcinoma accounts for 95% of human head and neck squamous cell carcinoma cases. It is highly malignant and aggressive, with a poor prognosis and a 5-year survival rate of <50%. In recent years, basic and clinical studies have been performed on the role of the mitogen-activated protein kinase (MAPK) signaling pathway in oral cancer. The MAPK signaling pathway is activated in over 50% of human oral cancer cases. Herein, we review research progress on the MAPK signaling pathway and its potential therapeutic mechanisms and discuss its molecular targeting to explore its potential as a therapeutic strategy for oral squamous cell carcinoma.

Chemokine-Cytokine Networks in the Head and Neck Tumor Microenvironment

Head and neck squamous cell carcinomas (HNSCCs) are aggressive diseases with a dismal patient prognosis. Despite significant advances in treatment modalities, the five-year survival rate in patients with HNSCC has improved marginally and therefore warrants a comprehensive understanding of the HNSCC biology. Alterations in the cellular and non-cellular components of the HNSCC tumor micro-environment (TME) play a critical role in regulating many hallmarks of cancer development including evasion of apoptosis, activation of invasion, metastasis, angiogenesis, response to therapy, immune escape mechanisms, deregulation of energetics, and therefore the development of an overall aggressive HNSCC phenotype. Cytokines and chemokines are small secretory proteins produced by neoplastic or stromal cells, controlling complex and dynamic cell-cell interactions in the TME to regulate many cancer hallmarks. This review summarizes the current understanding of the complex cytokine/chemokine networks in the HNSCC TME, their role in activating diverse signaling pathways and promoting tumor progression, metastasis, and therapeutic resistance development.

Targeting Cellular Metabolism Modulates Head and Neck Oncogenesis

Considering the great energy and biomass demand for cell survival, cancer cells exhibit unique metabolic signatures compared to normal cells. Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent neoplasms worldwide. Recent findings have shown that environmental challenges, as well as intrinsic metabolic manipulations, could modulate HNSCC experimentally and serve as clinic prognostic indicators, suggesting that a better understanding of dynamic metabolic changes during HNSCC development could be of great benefit for developing adjuvant anti-cancer schemes other than conventional therapies. However, the following questions are still poorly understood: (i) how does metabolic reprogramming occur during HNSCC development? (ii) how does the tumorous milieu contribute to HNSCC tumourigenesis? and (iii) at the molecular level, how do various metabolic cues interact with each other to control the oncogenicity and therapeutic sensitivity of HNSCC? In this review article, the regulatory roles of different metabolic pathways in HNSCC and its microenvironment in controlling the malignancy are therefore discussed in the hope of providing a systemic overview regarding what we knew and how cancer metabolism could be translated for the development of anti-cancer therapeutic reagents.

Thrombosis Risk Associated with Head and Neck Cancer: A Review

Venous thromboembolism (VTE) is a common complication for cancer patients. VTE-associated risk varies according to the type of tumor disease. Head and neck cancer is a common cancer worldwide, and most tumors are squamous cell carcinomas due to tobacco and alcohol abuse. The risk of VTE associated with head and neck (H&N) cancer is considered empirically low, but despite the high incidence of H&N cancer, few data are available on this cancer; thus, it is difficult to state the risk of VTE. Our review aims to clarify this situation and tries to assess the real VTE risk associated with H&N cancer. We report that most clinical studies have concluded that there is a very low thrombosis risk associated with H&N cancer. Even with the biases that often exist, this clinical review seems to confirm that the risk of VTE was empirically hypothesized. Furthermore, we highlight that H&N cancer has all the biological features of a cancer associated with a high thrombosis risk, including a strong expression of procoagulant proteins, modified thrombosis/fibrinolysis mechanisms, and secretions of procoagulant microparticles and procoagulant cytokines. Thus, this is a paradoxical situation, and some undiscovered mechanisms that could explain this clinical biological ambivalence might exist.

Clinical immunotherapeutic approaches for the treatment of head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide, accounting for more than 550,000 cases and 380,000 deaths annually. The primary risk factors associated with HNSCC are tobacco use and alcohol consumption; nevertheless genetic predisposition and oncogenic viruses also play important roles in the development of these malignancies. The current treatments for HNSCC patients include surgery, chemotherapy, radiotherapy, and cetuximab, and combinations of these. However, these treatments are associated with significant toxicity, and many patients are either refractory to the treatment or relapse after a short period. Despite improvements in the treatment of patients with HNSCC, the clinical outcomes of those who have been treated with standard therapies have remained unchanged for over three decades and the 5-year overall survival rate in these patients remains around 40-50%. Therefore, more specific and less toxic therapies are needed in order to improve patient outcomes. The tumour microenvironment of HNSCC is immunosuppressive; therefore immunotherapy strategies that can overcome the immunosuppressive environment and produce long-term tumour immunosurveillance will have a significant therapeutic impact in these patients. This review focuses on the current immunological treatment options under investigation or available for clinical use in patients with HNSCC.

The Proton-Sensing G-Protein Coupled Receptor GPR4 Promotes Angiogenesis in Head and Neck Cancer

Squamous cell carcinoma of the head and neck (SCCHN) is an aggressive disease with poor survival and is the sixth most common cancer worldwide. Gastroesophageal reflux is a common event in SCCHN patients. GPR4 is a proton-sensing G-protein coupled receptor, which can be activated by acidosis. The objective of this study was to explore the role of GPR4 in acid exposure and tumor angiogenesis in SCCHN. In this study, we confirmed that overexpressing GPR4 in SCCHN cells could increase the expression and secretion of IL6, IL8 and VEGFA at pH 5.9. This effect could be inhibited by SB203580 (a p38 inhibitor). Western blot analysis indicated that phosphorylation of p38 increased in GPR4 infected cells at pH 5.9, which could be inhibited by SB203580. In tube formation assay, HMEC-1 cells were incubated with conditioned medium (CM, pH 5.9, 6.5, 7.4) derived from control and GPR4 infected SCCHN cells. Tube length was significantly increased in HMEC-1 cells incubated with CM from GPR4 infected cells compared with control cells at pH5.9, which indicated the pro-angiogenic effect of GPR4 in acidic pH. The neutralizing antibodies of IL6, IL8 and VEGFA could inhibit tube formation of HMEC-1 cells. In vivo, the effect of GPR4 on angiogenesis was investigated with the chick chorioallantoic membrane (CAM) model. Control and GPR4 infected SCCHN cells were seeded onto the upper CAM surface (n = 5 in each group) and 5 μL DMEM/F12 (pH 5.9, 6.5, 7.4) was added to the surface of the cell every 24 h. Four days later, the upper CAM were harvested and the ratio of the vascular area to the CAM area was quantified using Image-Pro Plus 6.0 software. GPR4 infected cells could recruit more vascular than control cells at pH5.9. In conclusion, we suggested that GPR4 induces angiogenesis via GPR4-induced p38-mediated IL6, IL8 and VEGFA secretion at acidic extracellular pH in SCCHN.

Stromal expression of VEGF-A and VEGFR-2 in prostate tissue is associated with biochemical and clinical recurrence after radical prostatectomy

BACKGROUND

There is probably significant overtreatment of patients with prostate cancer due to a lack of sufficient diagnostic tools to predict aggressive disease. Vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) are potent mediators of angiogenesis and tumor proliferation, but have been examined to a limited extent in large prostate cancer studies. Meanwhile, recent promising results on VEGFR-2 inhibition have highlighted their importance, leading to the need for further investigations regarding their expression and prognostic impact.

DESIGN

Using tissue microarray and immunohistochemistry, the expression of VEGFs (VEGF-A and VEGF-C) and their receptors (VEGFR-2 and VEGFR-3) were measured in neoplastic tissue and corresponding stroma from radical prostatectomy specimens in 535 Norwegian patients. Their expression was evaluated semiquantatively and associations with event-free survival were calculated.

RESULTS

High expression of VEGFR-2 in either stroma or epithelium was independently associated with a higher incidence of prostate cancer relapse (HR = 4.56, P = 0.038). A high combined expression of either VEGF-A, VEGFR-2 or both in stroma was independently associated with a higher incidence of biochemical failure (HR = 1.77, P = 0.011).

CONCLUSIONS

This large study highlights the prognostic importance of VEGF-A and VEGFR-2 stromal expression. Analyses of these biomarkers may help distinguish which patients will benefit from radical treatment. Together with previous studies showing efficiency of targeting VEGFR-2 in prostate cancer, this study highlights its potential as a target for therapy, and may aid in future selection of prostate cancer patients for novel anti-angiogenic treatment.

The G protein-coupled receptor GALR2 promotes angiogenesis in head and neck cancer

Squamous cell carcinoma of the head and neck (SCCHN) is an aggressive disease with poor patient survival. Galanin receptor 2 (GALR2) is a G protein-coupled receptor that induces aggressive tumor growth in SCCHN. The objective of this study was to investigate the mechanism by which GALR2 promotes angiogenesis, a critical oncogenic phenotype required for tumor growth. The impact of GALR2 expression on secretion of proangiogenic cytokines in multiple SCCHN cell lines was investigated by ELISA and in vitro angiogenesis assays. Chemical inhibitor and genetic knockdown strategies were used to understand the key regulators. The in vivo impact of GALR2 on angiogenesis was investigated in mouse xenograft, chick chorioallantoic membrane, and the clinically relevant mouse orthotopic floor-of-mouth models. GALR2 induced angiogenesis via p38-MAPK-mediated secretion of proangiogenic cytokines, VEGF, and interleukin-6 (IL-6). Moreover, GALR2 activated small-GTP-protein, RAP1B, thereby inducing p38-mediated inactivation of tristetraprolin (TTP), which functions to destabilize cytokine transcripts. This resulted in enhanced secretion of proangiogenic cytokines and angiogenesis in vitro and in vivo. In SCCHN cells overexpressing GALR2, inactivation of TTP increased secretion of IL-6 and VEGF, whereas inhibition of p38 activated TTP and decreased cytokine secretion. Here, we report that GALR2 stimulates tumor angiogenesis in SCCHN via p38-mediated inhibition of TTP with resultant enhanced cytokine secretion. Given that p38 inhibitors are in clinical use for inflammatory disorders, GALR2/p38-mediated cytokine secretion may be an excellent target for new adjuvant therapy in SCCHN.

Is there a pAkt between VEGF and oral cancer cell migration?

The PI3K-Akt signalling pathway is a well-established driver of cancer progression. One key process promoted by Akt phosphorylation is tumour cell motility; however the mechanism of VEGF-induced Akt phosphorylation leading to motility remains poorly understood. Previously, we have shown that Akt phosphorylation induced by different factors causes both stimulation and inhibition of motility in different cell types. However, differential phosphorylation of Akt at T308 and S473 residues by VEGF and its role in head and neck cancer cell motility and progression is unknown. The cell lines investigated in this study exhibited a change in phosphorylation of Akt in response to VEGF. However, in terms of motility, VEGF stimulated oral cancer and its associated cell lines, but not normal keratinocytes or oral mucosal fibroblasts. The addition of a PI3 kinase and mTOR inhibitor, inhibited the phosphorylation of Akt and also effectively blocked VEGF-induced oral cancer cell motility, whereas only the PI3 kinase inhibitor blocked oral cancer associated fibroblast cell motility. This study therefore discloses that two different mechanisms of Akt phosphorylation control the motility potential of different cell lines. Akt phosphorylated at both residues controls oral cancer cell motility. Furthermore, immunohistochemical analysis of VEGF positive human head and neck tumour tissues showed a significant increase in Akt phosphorylation at the T308 residue, suggesting that pAkt T308 may be associated with tumour progression in vivo.

The expression of LC-3 is related to tumor suppression through angiogenesis in esophageal cancer

Autophagy is important in the development and remodeling of cells. It is required for cellular adaptation to nutrient deprivation and elimination of damaged organelles. Recently, autophagy has been implicated in carcinogenesis and metastasis. We hypothesized that autophagy-related proteins are initiated until nutrition is supplied by angiogenesis. We evaluated the clinicopathological significance of LC3, an autophagic marker, and its relationship to angiogenesis in patients with esophageal squamous cell carcinoma (ESCC). We immunohistochemically investigated the expression of LC3 as well as endoglin (CD105), a microvessel marker, and vascular endothelial growth factor A (VEGF-A) in 142 patients with ESCC. The high, moderate, and low expression rates of LC3 were 40, 31, and 29 %. LC3 expression inversely correlated with depth of invasion, lymph node metastasis, lymphatic invasion, MVD, VEGF-A expression, and poor prognosis. The overall survival rate was better in patients with high LC3 expression compared to patients with low LC3 expression. We demonstrate that low LC3 expression is related to tumor development as facilitated by angiogenesis and that alteration in LC3 expression is closely related to prognosis. Expression of LC3 proteins is a useful marker for determining tumor prognostic behavior in patients with ESCC.

Prognostic and predictive value of serum vascular endothelial growth factor (VEGF) in squamous cell carcinoma of the head and neck

INTRODUCTION

This study aimed to investigate the prognostic and predictive value of serum vascular endothelial growth factor (VEGF) in head and neck squamous cell carcinoma (HNSCC).

METHOD

Preoperative and 6-month postoperative serum VEGF levels were measured using a quantitative sandwich enzyme immunoassay technique in 55 consecutive patients with HNSCC and two control groups. The first control group included normal, healthy, age- and sex-matched individuals (n = 20), while the second control group included the patients who had history of HNSCC and were free of disease for at least 5 years (n = 25).

RESULTS

The mean baseline serum VEGF concentrations of the 55 patients with HNSCC and the first and the second control groups were 437.86, 42.56, and 48.03 pg/ml, respectively (P < 0.001). After a median follow-up of 75 months, 15 patients of the study group developed recurrent disease and 40 patients remained free of disease. The mean preoperative and 6-month postoperative serum VEGF levels for the 40 patients who did not have recurrent disease were respectively 327.69 and 153.50 pg/ml compared to 731.72 and 692.96 pg/ml for the 15 patients with recurrent disease (P < 0.001). High (≥540 pg/ml) serum VEGF level was associated with poor overall survival (P < 0.001). Moreover, multivariate analysis showed node stage (P < 0.001) and preoperative serum VEGF level (P = 0.020) as significant, independent prognostic factors for overall survival.

CONCLUSION

Preoperative or postoperative elevated serum levels of VEGF are highly predictive for disease recurrence and are associated with poor disease-free and overall survival of patients with HNSCC.

Established and novel NF-κB inhibitors lead to downregulation of TLR3 and the proliferation and cytokine secretion in HNSCC

The transcriptional activation of NF-κB signalling has been identified as a major pathway involved in inflammation and tumor aggressiveness in a number of human cancers. Here we identify the impact of miscellaneous known and so far unknown NF-κB inhibitors originating from different drug classes on the function and proliferation of HNSCC. In detail: HNSCC cell lines were exposed to Acetylsalicylic Acid (ASA), Celecoxib, Dexamethasone, Curcumin and EPs 7630. Our major interest was to detect upstream alterations in cell signalling after applying NF-κB inhibiting substances. The inhibition of NF-κB signalling leads to an upstream regulation of Toll-like-receptor 3 (TLR3), a predominant receptor driving cell expansion. We find a marked downregulation of TLR3 and IKK complex, documenting upstream responses to NF-κB inhibition by every agent tested. In a second step we further analyse proliferation, cytokine production and alterations in the expression of downstream proteins such as cyclin D1 and c-Myc. Our data demonstrate decreased proliferation in response to incubation with aforementioned agents. Modulation of TLR3 and NF-κB expression is accompanied by altered profiles of IL-6 and IL-8 which are relevant cytokines in HNSCC progression. Proto-oncogenes cyclin D1 and c-myc are downregulated by all substances. Apart from the interplay of cytokines and TLR3, we substantiated EPs 7630 as a new and natural NF-κB inhibitor.

VEGF expression and angiogenesis in oral squamous cell carcinoma: an immunohistochemical and morphometric study

Angiogenesis is involved in tumor progression of oral squamous cell carcinoma (OSCC). In this study, we have investigated by immunohistochemistry vascular endothelial growth factor (VEGF) expression in tumor cells and we have correlated VEGF expression to microvessel area, evaluated by using CD105 as a marker of endothelial cells, in bioptic specimens of 54 human OSCC. Results demonstrated that VEGF is highly expressed in OSCC tumor specimens when compared to pre-neoplastic and normal tissues, without differences between the edge and inside the tumor. Moreover, VEGF expression is reduced in poor differentiated OSCC tumors when compared to moderate and good differentiated forms, and tumor microvessel area is higher in tumors when compared to pre-neoplastic lesions and normal tissues. Finally, VEGF and CD105 may be considered as reliable markers of tumor angiogenesis and progression in OSCC, even if we did not demonstrate any correlation between VEGF expression, tumor microvascular area, clinical stage, and lymph node status.

Cross talk initiated by endothelial cells enhances migration and inhibits anoikis of squamous cell carcinoma cells through STAT3/Akt/ERK signaling

It is well known that cancer cells secrete angiogenic factors to recruit and sustain tumor vascular networks. However, little is known about the effect of endothelial cell-secreted factors on the phenotype and behavior of tumor cells. The hypothesis underlying this study is that endothelial cells initiate signaling pathways that enhance tumor cell survival and migration. Here, we observed that soluble mediators from primary human dermal microvascular endothelial cells induce phosphorylation of signal transducer and activator of transcription 3 (STAT3), Akt, and extracellular signal-regulated kinase (ERK) in a panel of head and neck squamous cell carcinoma (HNSCC) cells (OSCC-3, UM-SCC-1, UM-SCC-17B, UM-SCC-74A). Gene expression analysis demonstrated that interleukin-6 (IL- 6), interleukin-8 (CXCL8), and epidermal growth factor (EGF) are upregulated in endothelial cells cocultured with HNSCC. Blockade of endothelial cell-derived IL-6, CXCL8, or EGF by gene silencing or neutralizing antibodies inhibited phosphorylation of STAT3, Akt, and ERK in tumor cells, respectively. Notably, activation of STAT3, Akt, and ERK by endothelial cells enhanced migration and inhibited anoikis of tumor cells. We have previously demonstrated that Bcl-2 is upregulated in tumor microvessels in patients with HNSCC. Here, we observed that Bcl-2 signaling induces expression of IL-6, CXCL8, and EGF, providing a mechanism for the upregulation of these cytokines in tumor-associated endothelial cells. This study expands the contribution of endothelial cells to the pathobiology of tumor cells. It unveils a new mechanism in which endothelial cells function as initiators of molecular crosstalks that enhance survival and migration of tumor cells.

Systemic therapies for squamous cell carcinoma of the head and neck

OBJECTIVES

To discuss current clinical recommendations for treatment of squamous cell carcinoma of the head and neck (SCCHN), to identify common toxicities associated with combined chemoradiotherapy or chemotherapy alone, and describe strategies for management of the most common treatment-related toxicities.

DATA SOURCES

Current research, published literature, National Comprehensive Cancer Network Clinical Practice Guidelines, American Society of Clinical Oncology, and Oncology Nursing Society.

CONCLUSION

Advances in options for systemic therapy for SCCHN have provided hope for patients with this disease. However, effective management of these patients requires a proactive and persistent multidisciplinary treatment approach, including toxicity management.

IMPLICATIONS FOR NURSING PRACTICE

Careful evaluation of each patient before initiating treatment with the goals of therapy reviewed by the multidisciplinary team, the patient, and the caregivers, will allow selection of the most appropriate treatment plan. The goals of therapy should provide guidance in balancing tumor response, toxicity (both acute and late effects), survival, and quality of life.

Bevacizumab for the treatment of advanced non-small-cell lung cancer

Until recently, advances in non-small-cell lung cancer (NSCLC) care have been limited; new chemotherapy regimens have not significantly impacted patient survival. With our improved understanding of tumor biology, novel biological therapies targeting key tumorigenic processes targeting factors essential for tumor growth, such as angiogenesis, have been developed that improve patient outcomes beyond those achieved with chemotherapy alone. One of these, bevacizumab (Avastin), specifically targets VEGF, which is key to the malignant growth and progression of solid tumors. Bevacizumab-based therapy until progression significantly delays disease progression, has a well-characterized and acceptable safety profile in bevacizumab-eligible patients and was the first treatment to improve the overall survival of patients with advanced NSCLC beyond 1 year, a significant breakthrough in advanced NSCLC care. Furthermore, bevacizumab-based therapy significantly delays disease progression and has a well-characterized and acceptable safety profile. Based on these data, bevacizumab has received approval for the first-line treatment of NSCLC in the USA and Europe. A number of ongoing trials will potentially expand the eligible patient population for bevacizumab and further define its role in NSCLC treatment.

Vascular endothelial growth factor (VEGF), VEGF receptors expression and microvascular density in benign and malignant thyroid diseases

Angiogenesis is critical for the growth and metastatic spread of tumours. Vascular endothelial growth factor (VEGF) is the most potent inducer of neovasculature, and its increased expression has been related to a worse clinical outcome in many diseases. The purpose of this study was to evaluate the relation between VEGF, its receptors (VEGFR-1 and VEGFR-2) and microvessel density (MVD) in thyroid diseases. Immunostaining for VEGF and VEGF receptors was performed in 66 specimens of thyroid tissue, comprising 17 multinodular goitre (MNG), 14 Graves' disease, 10 follicular adenoma, 8 Hashimoto's thyroiditis, 7 papillary carcinoma and 10 normal thyroid specimens. Thyrocyte positivity for VEGF and VEGF receptors was scored 0-3. Immunohistochemistry for CD31, and CD34 on the same sections was performed to evaluate MVD. Immunohistochemical staining of VEGF in thyrocytes was positive in 92% of all the thyroid tissues studied. Using an immunostaining intensity cut off of 2, increased thyrocyte staining was seen in follicular adenoma specimens, MNG and normal thyroids compared with Hashimoto's thyroiditis and Graves' disease (P < 0.05). Similarly, VEGF thyrocyte expression in Graves' disease was less than other pathologies (P < 0.05). VEGFR-1 expression and the average MVD score did not differ between the different thyroid pathologies. VEGF expression was lower in autoimmune pathologies compared to autonomous growth processes. Conversely, both VEGFR-1 and VEGFR-2 were widely expressed in benign and neoplastic thyroid disease, suggesting that the up-regulation of VEGF and not its receptors occurs as tissue becomes autonomous. There was no clear relationship between MVD measurement and thyroid pathology.

Combination of radiotherapy with EGFR antagonists for head and neck carcinoma

The introduction of biologically sound radiation fractionation regimens and combinations of radiotherapy with chemotherapy have gradually improved both the survival of patients with locally advanced head and neck squamous cell carcinoma (HNSCC) and the prospect of organ preservation. Long-term follow-up, however, has shown that some of the radiation-chemotherapy combinations are associated with increased late toxicity. This observation, in conjunction with advances in tumor biology, has led to the launch of investigations into molecular markers and targets for therapeutic interventions. Research on the epidermal growth factor receptor (EGFR)-mediated signaling pathway has enriched our understanding of the biology of HNSCC, in terms of carcinogenesis and cellular processes governing tumor response to therapy. The finding that the addition of an antibody-based inhibitor of the EGFR pathway to radiotherapy significantly improves locoregional control and overall survival rates in patients with locally advanced HNSCC, without increasing radiation-induced toxicity, has resulted in the growing acceptance of such combined regimens as a frontline therapy option for locally advanced HNSCC. Because such therapy has benefited only an additional 10%-15% of patients, studies are being undertaken to identify markers and mechanisms of resistance to EGFR antagonists that are essential for the further refinement of therapy. Overall, preclinical and clinical studies on EGFR have validated the concept that selective tumor radiation sensitization can be achieved by modulating a specific perturbed signaling pathway, and these studies have increased the enthusiasm for developing and investigating other novel agents targeting other cellular processes.

Challenges for patient selection with VEGF inhibitors

As targeted therapies for cancer become increasingly integrated into standard practice, appropriate selection of the patients most likely to benefit from these therapies is now receiving critical scrutiny. Early experience with therapies directed at targets that are definitively overactive (e.g. the bcr-abl tyrosine kinase targeted by imatinib) or over-expressed [e.g. the human epidermal growth factor receptor 2 (HER2) targeted by trastuzumab] has generated the perception that pre-treatment target assessment is a pre-requisite for therapy with all targeted agents. However, emerging evidence suggests that this is not presently feasible for anti-angiogenic agents. Despite considerable evidence for the association of intratumoral and/or plasma vascular endothelial growth factor (VEGF) levels with tumor progression and/or poor prognosis, pre-treatment VEGF levels do not appear to be predictive of response to anti-angiogenic therapy. This may possibly be due to the complexity of the angiogenic pathways and the limitations associated with current methods of VEGF detection and quantification; e.g. low assay sensitivity and lack of standardized methods could prevent detection of very small increases in VEGF, which may be clinically important in patients with tumors that are highly dependent on this growth factor. In addition to a general lack of agreement as to the relative clinical relevance of circulating versus tumor VEGF levels, the absence of a 'gold standard' VEGF detection assay and the lack of a predefined, clinically relevant cut-off pose a significant hindrance to the clinical utility of VEGF measurements for therapy selection. Given the fundamental importance of angiogenesis for tumor growth and progression, and the key role of VEGF in these processes, presently it seems appropriate to view anti-VEGF agents such as bevacizumab (Avastin) as having potential utility, independently of pre-treatment screening. Further research is needed to define the relationship between potential surrogate markers of VEGF pathway activity and clinical outcomes.

Serum vascular endothelial growth factor in patients with pharyngeal and laryngeal squamous cell carcinoma treated with radiotherapy

The aim of this study was to assess the impact of radiotherapy on serum vascular endothelial growth factor (VEGF) levels in patients with pharyngeal and laryngeal cancer. Serum VEGF concentrations were determined in 37 patients before, during, and after radiotherapy by using a quantitative sandwich enzyme immunoassay technique. Most (25 patients [68%]) of the studied population were found to have high pretreatment VEGF concentration (of >700 pg/mL; median, 796.3 pg/mL). During radiotherapy, after receiving the total dose of 40 Gy, the median level of serum VEGF remained unchanged (795.2 pg/mL). Regardless of the treatment results, 2 months after completing irradiation the median VEGF level decreased to 448.9 pg/mL, and the difference between pre- and posttreatment medians was statistically significant (P < .05). No association between pretreatment serum VEGF concentrations and the size of tumor, lymph node status, and patients' age was found. The findings that radiotherapy produces serum VEGF decline in primary pharyngeal and laryngeal carcinomas (P = .065) may be related to the blocking effect of radiation on local angiogenesis.

Influence of L-thyroxine administration on poor-platelet plasma VEGF concentrations in patients with induced short-term hypothyroidism, monitored for thyroid carcinoma

Angiogenesis is a process of new blood vessel development from pre-existing vasculature. It is a crucial process in normal physiology, as well as in several pathological conditions. The vascular endothelial growth factor (VEGF) represents a family of specific endothelial cell mitogens, involved in normal angiogenesis and in tumour development. The aim of the present study was to estimate the influence of L-thyroxine (L-T4) administration on poor-platelet plasma (P-PP) VEGF concentrations in patients with induced short-term hypothyroidism, monitored for differentiated thyroid carcinoma. In the present study, P-PP concentrations of VEGF, thyroglobulin, thyrotropin and free thyroid hormones were investigated in a population of 24 hypothyroid patients, who were withdrawn from L-T4 treatment for 5 weeks and studied before and after 2 months of L-T4 therapy. Only healthy female patients with no evidence of metastasis in whole body scintigraphy were included in the study. They were then compared with 20 healthy control subjects, matched for age, sex and body mass index (BMI). The patients had significantly lower plasma VEGF concentrations before treatment with L-T4 than after administration of that hormone. There was no significant difference in plasma VEGF levels, either between the patients treated with L-T4, and the controls, or between the patients untreated with L-T4, and the controls. Even short-time changes in thyrometabolic profile exert an important influence on P-PP VEGF concentrations, even if there is no thyroid tissue.

Role of cytokines in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma is one of the most frequent cancers and standard treatment has only marginally improved the 5-year survival rate of patients with this disease in the last few decades. It is supposed that cytokine alterations in immune, inflammatory and angiogenetic regulatory routes within the head and neck squamous cell carcinoma microenvironment play a critical role in tumor aggressiveness, its response to chemo- and radiation therapies, as well as the development of immune escape mechanisms.

Epidermal growth factor receptor biology in head and neck cancer

Epidermal growth factor receptor (EGFR) is overexpressed in several epithelial malignancies, including head and neck squamous cell carcinoma (HNSCC), which exhibits EGFR overexpression in up to 90% of tumors. EGFR ligands such as transforming growth factor alpha are also overexpressed in HNSCC. EGFR plays a critical role in HNSCC growth, invasion, metastasis and angiogenesis. However, EGFR inhibitors as monotherapy have yielded only modest clinical outcomes. Potential mechanisms for lack of response to EGFR inhibition in HNSCC include constitutive activation of signaling pathways independent of EGFR, as well as genetic aberrations causing dysregulation of the cell cycle. EGFR-directed therapy may be optimized by identifying and selecting those HNSCC patients most likely to benefit from EGFR inhibition. Resistance to EGFR inhibition may be circumvented by combination therapy employing EGFR inhibitors together with other treatment modalities.

Molecular markers of head and neck squamous cell carcinoma: promising signs in need of prospective evaluation

BACKGROUND

The aim of this article is to review recent developments in the biological understanding of head and neck squamous cell carcinomas.

METHODS AND RESULTS

We describe the markers according to their function and their prognostic or predictive roles. Some associations can be found between molecular markers and invasiveness, aggressiveness, degree of differentiation, and tumor stage, but only a few clinical studies have shown an impact on prognosis. In addition, despite an increasing number of articles relating to this topic, the small number of patients included in the studies reported reduces the clinical implications of these results. Few studies applied a more comprehensive molecular analysis approach, such as DNA microarrays or differential expression profiling by polymerase chain reaction, to identify a combination of markers that could be more informative than a single molecular marker.

CONCLUSION

Some progress has been made with respect to molecular markers and head and neck cancers. Translational and prospective, hypothesis-driven research must proceed with sufficient rigor to facilitate the clinical applicability of such results.

Vascular endothelial growth factor-A and Poly(A) binding protein-interacting protein 2 expression in human head and neck carcinomas: correlation and prognostic significance

Vascular endothelial growth factor-A (VEGF-A) has been demonstrated to play an important role in tumour angiogenesis and to influence prognosis in many cancers. However its prognostic value in head and neck squamous cell carcinomas (HNSCCs) remains controversial. Therefore, we investigated the clinical relevance of VEGF-A expression in HNSCCs and analysed whether its expression was associated with PAIP2 protein levels, a VEGF-A mRNA-binding partner that strongly regulates VEGF-A expression in tissue culture. We determined the correlation of VEGF-A and PAIP2 protein levels, quantitatively evaluated in tumour tissue homogenates from 54 patients with HNSCC, to clinicopathological parameters. We showed that VEGF-A expression in HNSCC is correlated to the stage of tumour differentiation (P=0.050) and is an independent prognostic factor for progression-free survival (P=0.001) and overall survival (P=0.0004). In a pharynx carcinoma cell line, we demonstrated by RNA interference that VEGF-A expression is closely controlled by PAIP2. Moreover, in human HNSCCs, VEGF-A expression is significantly correlated to PAIP2 protein levels (P=0.0018). Nevertheless, PAIP2 expression is associated with neither clinicopathological factors nor patient's survival. Our data suggest that, in contrast to PAIP2 protein levels, which are unrelated to tumour prognosis, VEGF-A expression could serve as a prognostic marker in head and neck cancer and may be helpful for targeted therapies.

IGF-1 induced vascular endothelial growth factor secretion in head and neck squamous cell carcinoma

Elevated vascular endothelial growth factor (VEGF) levels correlate with increased progression and poor prognosis of head and neck squamous cell carcinomas (HNSCC). VEGF expression is regulated by hypoxia and cytokines, including insulin-like growth factor-1 (IGF-1). In this report, we examined IGF-1 signaling and VEGF expression in SCC-9 cells. IGF-1 and the chemical hypoxia agent, cobalt chloride, each stimulated VEGF secretion and VEGF promoter activation. Cobalt chloride increased Hif-1alpha protein levels and HIF-1 dependent activation of the enolase promoter. IGF-1 increased these parameters only in the presence of cobalt chloride. IGF-1 stimulated PI-3K/Akt and Erk/MAPK pathways in SCC-9 cells, each contributing to Hif-1alpha expression and VEGF secretion. SCC-9 cells express the VEGF receptors Flk-1 and neuropilin-1, with VEGF treatment increasing VEGF promoter activity and VEGF secretion that was attenuated by the Flk-1 tyrosine kinase inhibitor, ZM 323881. These results demonstrate the presence of an IGF-1 regulated VEGF autocrine loop in HNSCC.

Prognostic significance of vascular endothelial growth factor immunohistochemical expression in head and neck squamous cell carcinoma: a meta-analysis

PURPOSE

Vascular endothelial growth factor (VEGF) is considered as a prime mediator of angiogenesis. Various studies examining the relationship between VEGF protein overexpression with the clinical outcome in patients with head and neck squamous cell carcinoma have yielded inconclusive results.

EXPERIMENTAL DESIGN

We conducted a meta-analysis of 12 studies (n = 1.002 patients) that evaluated the correlation between VEGF (detected by immunohistochemistry) and 2-year overall survival. The relation between VEGF and lymph node involvement (11 studies, n = 722) was also examined. Data were synthesized with random effect and fixed effect risk ratios.

RESULTS

The estimated risk of death in 2 years was 1.88-fold higher in the VEGF-positive patients [95% confidence interval, 1.43-2.45; P < 0.001 random effect calculations]. Between-study heterogeneity was nonsignificant (P = 0.15) but larger studies tended to provide more conservative estimates (P = 0.097). VEGF overexpression was not significantly associated with the presence of lymph node metastasis (risk ratio, 1.20; 95% confidence interval, 0.97-1.49; P = 0.087) and there was significant between-study heterogeneity (P = 0.08).

CONCLUSIONS

Although some modest bias cannot be excluded, VEGF positivity seems to be associated with worse overall survival in patients with head and neck squamous cell carcinoma.

Stromelysin 3, Ets-1, and vascular endothelial growth factor expression in oral precancerous and cancerous lesions: correlation with microvessel density, progression, and prognosis

PURPOSE

Identification of molecular changes characteristic of development and progression of oral cancer are of paramount importance for effective intervention. Stromelysin 3 (MMP11) is a unique matrix metalloproteinase shown to have dual function during cancer progression. The transcription factor Ets-1 and vascular endothelial growth factor (VEGF) are important proangiogenic factors in cancer. This study was designed to test the hypothesis that concomitant expression of stromelysin 3, Ets-1, and/or VEGF affects the development, progression, and prognosis of oral cancer.

PATIENTS AND METHODS

Immunohistochemical analysis of stromelysin 3, Ets-1, VEGF, and platelet/endothelial cell adhesion molecule 1 (a marker for intratumoral microvessel density) was carried out in serial paraffin embedded tissue sections of 220 oral squamous cell carcinomas (OSCC), 90 precancerous lesions (59 hyperplasias and 31 dysplasias), and 81 matched histologically normal oral tissues.

RESULTS

Ets-1, VEGF, and stromelysin 3 expression independently correlated with increased intratumoral microvessel density in precancerous lesions (P = 0.05, 0.001, and 0.026, respectively) as well as in SCCs (P = 0.005, 0.01, and 0.031, respectively). Logistic regression analysis revealed that concomitant expression of stromelysin 3 and Ets-1 (stromelysin 3(+)/ Ets-1(+) phenotype; odds ratio, 3.7; P = 0.001) was the most significant predictor for transition to precancerous stage, whereas dual expression of stromelysin 3 and VEGF (stromelysin 3(+)/ VEGF(+) phenotype; odds ratio, 2.07; P = 0.004) was the most important predictor for progression from precancerous stage to frank malignancy. Intriguingly, Ets-1 expression was significantly associated with VEGF expression and stromelysin 3 expression in precancerous tissues as well as OSCCs. Follow-up data for 144 patients for a maximum period of 115 months showed that VEGF [hazards ratio (HR), 4.532; P = 0.004] and Ets-1 (HR = 2.182; P = 0.049) expression significantly correlated with reduced disease-free survival in univariate analysis. In bivariate analysis, patients harboring Ets-1(+)/VEGF(+) phenotype had the worst survival (median disease-free survival, 50 months; HR, 2.943; P = 0.003). Multivariate analysis using Cox's proportional hazards model showed that increased VEGF expression was the most significant adverse prognosticator in OSCC patients (HR, 4.470; P = 0.004).

CONCLUSIONS

In conclusion, this study provides the first evidence of concomitant expression of stromelysin 3, VEGF, and Ets-1 in clinical specimens in different stages of development of oral cancer. In early stages, concomitant expression of stromelysin 3 and Ets-1 favors the development of a precancerous state, whereas dual expression of stromelysin 3 and VEGF is associated with progression from precancerous to cancerous state. VEGF expression is an adverse prognosticator for disease-free survival.

Imaging hypoxia and angiogenesis in tumors

There is a clear need in cancer treatment for a noninvasive imaging assay that evaluates the oxygenation status and heterogeneity of hypoxia and angiogenesis in individual patients. Such an assay could be used to select alternative treatments and to monitor the effects of treatment. Of the several methods available, each imaging procedure has at least one disadvantage. The limited quantitative potential of single-photon emission CT and MR imaging always limits tracer imaging based on these detection systems. PET imaging with FMISO and Cu-ATSM is ready for coordinated multicenter trials, however, that should move aggressively forward to resolve the debate over the importance of hypoxia in limiting response to cancer therapy. Advances in radiation treatment planning, such as intensity-modulated radiotherapy, provide the ability to customize radiation delivery based on physical conformity. With incorporation of regional biologic information, such as hypoxia and proliferating vascular density in treatment planning, imaging can create a biologic profile of the tumor to direct radiation therapy. Presence of widespread hypoxia in the tumor benefits from a systemic hypoxic cell cytotoxin. Angiogenesis is also an important therapeutic target. Imaging hypoxia and angiogenesis complements the efforts in development of antiangiogenesis and hypoxia-targeted drugs. The complementary use of hypoxia and angiogenesis imaging methods should provide the impetus for development and clinical evaluation of novel drugs targeted at angiogenesis and hypoxia. Hypoxia imaging brings in information different from that of FDG-PET but it will play an important niche role in oncologic imaging in the near future. FMISO, radioiodinated azamycin arabinosides, and Cu-ATSM are all being evaluated in patients. The Cu-ATSM images show the best contrast early after injection but these images are confounded by blood flow and their mechanism of localization is one step removed from the intracellular O2 concentration. FMISO has been criticized as inadequate because of its clearance characteristics, but its uptake after 2 hours is probably the most purely reflective of regional PO2 at the time the radiopharmaceutical is used. The FMISO images show less contrast than those of Cu-ATSM because of the lipophilicity and slower clearance of FMISO but attempts to increase the rate of clearance led to tracers whose distribution is contaminated by blood flow effects. For single-photon emission CT the only option is radioiodinated azamycin arabinosides, because the technetium agents are not yet ready for clinical evaluation. Rather than develop new and improved hypoxia agents, or even quibbling about the pros and cons of alternative agents, the nuclear medicine community needs to convince the oncology community that imaging hypoxia is an important procedure that can lead to improved treatment outcome.

The novel targets for anti-angiogenesis of genistein on human cancer cells

Genistein has been reported to be a natural chemopreventive in several types of human cancer. In our prior study, soy isoflavones were shown to induce cell cycle arrest and apoptosis of bladder cancer cells in the range of human urine excretion. This study was designed to identify the novel molecular basis underlying anti-angiogenic activities of soy isoflavones. An immortalized E6 and five human bladder cancer cell lines were studied by immunoassay, flow cytometry, functional activity, reverse transcription-polymerase chain reaction, immunoblotting, and transwell co-culture in vitro. The efficacy of soy isoflavones on angiogenesis inhibition in vivo was examined by nude mice xenograft and chick chorioallantoic membrane bioassay. Factors analyzed included angiogenic factors, matrix-degrading enzymes, and angiogenesis inhibitors. Genistein was the most potent inhibitor of angiogenesis in vitro and in vivo among the isoflavone compounds tested. It may also account for most of the reduced microvessel density of xenografts observed and the suppressed endothelial migration by soy isoflavones. Genistein exhibited a dose-dependent inhibition of expression/excretion of vascular endothelial growth factor165, platelet-derived growth factor, tissue factor, urokinase plasminogen activator, and matrix metalloprotease-2 and 9, respectively. On the other hand, there was an up-regulation of angiogenesis inhibitors-plasminogen activator inhibitor-1, endostatin, angiostatin, and thrombospondin-1. In addition, a differential inhibitory effect between immortalized uroepithelial cells and most cancer cell lines was also observed. Altogether, we discovered that tissue factor, endostatin, and angiostatin are novel molecular targets of genistein. The current investigation provides further evidence in support of soy-based foods as natural dietary inhibitors of tumor angiogenesis.

Identification of a gene expression signature associated with recurrent disease in squamous cell carcinoma of the head and neck

Molecular studies of squamous cell carcinoma of the head and neck (HNSCC) have demonstrated multiple genetic abnormalities such as activation of various oncogenes (Ras, Myc, epidermal growth factor receptor, and cyclin D1), tumor suppressor gene inactivation (TP53 and p16), and loss of heterozygosity at numerous chromosomal locations. Despite these observations, accurate and reliable biomarkers that predict patients at highest risk for local recurrence have yet to be defined. In an effort to identify gene expression signatures that may serve as biomarkers, we studied 41 squamous cell carcinoma tumors (25 primary and 16 locally recurrent) from various anatomical sites and 13 normal oral mucosal biopsy samples from healthy volunteers with microarray analysis using Affymetrix U133A GeneChip arrays. Differentially expressed genes were identified by calculating generalized t tests (P < 0.001) and applying a series of filtering criteria to yield a highly discriminant list of 2890 genes. Hierarchical clustering and image generation using standard software were used to visualize gene expression signatures. Several gene expression signatures were readily identifiable in the HNSCC tumors, including signatures associated with proliferation, extracellular matrix production, cytokine/chemokine expression, and immune response. Of particular interest was the association of a gene expression signature enriched for genes involved in tumor invasion and metastasis with patients experiencing locally recurrent disease. Notably, these tumors also demonstrated a marked absence of an immune response signature suggesting that modulation of tumor-specific immune responses may play a role in local treatment failure. These data provide evidence for a new gene expression-based biomarker of local treatment failure in HNSCC.

Vascular endothelial growth factor C and vascular endothelial growth factor receptor 3 expression in squamous cell carcinomas of the head and neck

BACKGROUND AND METHODS

VEGF proteins and their receptors are involved in tumor vessel neoformation. The third VEGF receptor, VEGFR3 (flt-4) is important during both blood vessel development and lymphatic vessel formation. Because HNSCC preferentially metastasizes to regional lymph nodes, we investigated the expression of VEGFR3 and its ligand VEGF-C in head and neck squamous cell carcinomas by semiquantitative RT-PCR (4 HNSCC cells lines and 6 HNSCC specimens) and by immunohistochemistry (18 HNSCC specimens). VEGFR3 protein expression was confirmed by Western blotting in four HNSCC cell lines and six HNSCC specimens.

RESULTS

Semiquantitative mRNA analysis showed VEGF-C mRNA expression in three (SCC9, SCC25, LFFR) of four HNSCC cell lines and all six HNSCC specimens. VEGFR3 mRNA was found in two HNSCC cell lines (JPPA and SCC25) and only weakly detected in the other two HNSCC cell lines (SCC9 and LFFR). High amounts of VEGFR3 mRNA were shown in all six patients' tumor specimens. VEGFR3 Western blot analysis yielded a distinct band at the predicted size of 210 kD in JPPA and SCC9 and hardly detectable bands in SCC25 and LFFR cell lines. All six HNSCC specimens displayed strong VEGFR3 protein bands. Immunohistochemistry in 18 HNSCC specimens assigned strong to mediate VEGF-C IR and minor VEGFR3 IR to tumor cells and strong VEGF-C and VEGFR3 IR to tumor surrounding vessels. In addition, intense VEGF-C immunostaining was observed on perivascular and mononuclear cells in the tumor surrounding stroma. Subtyping of VEGFR3+ microvascular tumor vessels revealed partially double immunolabeling with CD34 and flk-1, indicating a common origin of blood and lymphatic vessels. The expression of VEGF-C on tumor cells could be correlated with recurrences, and larger primary tumors had more VEGF-C-positive vessels.

CONCLUSIONS

The broad expression of VEGF C and VEGFR3 in HNSCC suggests involvement in tumor lymph angiogenesis and vascular angiogenesis, promoting tumor growth and propagation of cancer cells. This implies that inhibitors of lymph angiogenesis could become effective therapeutic options similar to classical angiogenesis inhibitors.

Angiogenesis in epithelian ovarian cancer

Angiogenesis, the development of new blood vessels from the existing vasculature, is an essential component of solid tumour growth and metastasis. Several angiogenic factors are expressed by many tumours, suggesting that tumours promote their own vascularisation by activating the host endothelium. This review will discuss various angiogenic stimulators and inhibitors in epithelian ovarian cancer (EOC), including vascular endothelial growth factor and platelet derived endothelial cell growth factor/thymidine phosphorylase. The analysis of tumour vascularisation by microvessel density will also be discussed and the relevance of these markers of angiogenesis in the prognosis of EOC will be assessed.

Expression of vascular endothelial growth factor in basal cell carcinoma and cutaneous squamous cell carcinoma of the head and neck

BACKGROUND

Basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) can both arise from any cutaneous epithelial surface. BCC are slow growing and rarely metastasise, whereas SCC are usually more aggressive. It is likely that the angiogenic process plays a key role in determining rate of growth and propensity for dissemination. Angiogenesis is a complex process requiring many factors and a pivotal group of proteins involved in this process is vascular endothelial growth factor (VEGF).

METHODS

Immunohistochemical expression of VEGF was assessed in 44 cases of BCC and 41 cases of cutaneous SCC from the head and neck region.

RESULTS

VEGF was expressed by blood vessel endothelial cells in both adjacent skin and tumour, and in the basal keratinocyte layer of epidermis. In BCC, VEGF was expressed by tumour epithelial cells, predominantly at the invasive tumour front, in 24/44 cases and its expression was significantly greater than in adjacent skin (p = 0.038). More widespread VEGF expression was found in 32/41 cases of SCC, and it was significantly associated with the degree of tumour differentiation (p < 0.001).

CONCLUSIONS

The patterns of VEGF expression in BCC and SCC may help to explain the different behaviour that is usually seen with these tumours.

CDK4 coexpression with Ras generates malignant human epidermal tumorigenesis

Ras acts with other proteins to induce neoplasia. By itself, however, strong Ras signaling can suppress proliferation of normal cells. In primary epidermal cells, we found that oncogenic Ras transiently decreases cyclin-dependent kinase (CDK) 4 expression in association with cell cycle arrest in G1 phase. CDK4 co-expression circumvents Ras growth suppression and induces invasive human neoplasia resembling squamous cell carcinoma. Tumorigenesis is dependent on CDK4 kinase function, with cyclin D1 required but not sufficient for this process. In facilitating escape from G1 growth restraints, Ras and CDK4 alter the composition of cyclin D and cyclin E complexes and promote resistance to growth inhibition by INK4 cyclin-dependent kinase inhibitors. These data identify a new role for oncogenic Ras in CDK4 regulation and highlight the functional importance of CDK4 suppression in preventing uncontrolled growth.

VEGF in the culture of PMN and the serum in oral cavity cancer patients

Vascular endothelial growth factor (VEGF) is a multifunctional cytokine that plays a pivotal role in angiogenesis in vivo. In the present study we examined the ability of polymorphonuclear neutrophils (PMN) to secrete VEGF confronted with the serum levels in oral cavity cancer patients. To investigate whether VEGF may have a prognostic importance, its value in the serum and the culture supernatants was related to the clinical course of patients. The levels of VEGF in the culture supernatant of PMN from patients were significantly higher than those from control. Increased VEGF production by PMN according to clinical progression disease, observed in the present study, seems to suggest a stimulating role of tumour cells in VEGF production by PMN. Additionally, a decrease in the ability of PMN to VEGF release after surgery may be caused by a removal of the tumour mass and then the lack the effects of tumour cells on PMN function. Results obtained appear to suggest that PMN can contribute significantly to the initiation and amplification of tumour angiogenesis and metastasis in oral cavity cancer patients. Increased values of VEGF with progression of disease and decreased values after surgery treatment clearly suggest that VEGF can play a role as a tumour marker in oral cavity cancer patients.

Inhibition of vascular endothelial growth factor in the treatment of solid tumors

Vascular endothelial growth factor (VEGF) is the term used for a family of tumor-derived angiogenic factors that mediate endothelial proliferation and vascular permeability. Preclinical models have demonstrated the essential nature of VEGF in the angiogenesis of solid tumor growth and metastasis, whereas pathologic investigations have revealed strong correlations between VEGF production, microvessel density, and overall aggressiveness of many human solid tumors. Recent advances in the understanding of the molecular mechanisms of VEGF action have led to successful models for intervention in VEGF-mediated pathways in therapy for solid tumors. These include antibodies to block the binding of VEGF to its cellular receptors, small-molecule chemical inhibitors of the tyrosine kinase functions of the VEGF receptors, and antisense nucleic acids to interfere with cellular production of VEGF. Clinical investigations are ongoing to test the value of VEGF-based intervention alone or in combination with other anticancer agents.

Hypoxia and VEGF mRNA expression in human tumors

High expression of circulating plasma vascular endothelial growth factor (VEGF) in patients with cancer is an indicator of poor treatment response. Similarly, hypoxia in tumors, as measured by oxygen needle electrodes, has been found to predict for tumor-treatment failure. These two predictors may be related because hypoxia is a potent stimulator of VEGF expression in vitro. However, the demonstration of a relationship between hypoxia and VEGF in human tumors has, to date, been indirect or even negative. The purpose of this study was to test whether this unexpected result was caused by factors unique to human tumors, or whether the prior results could have been influenced by the known complexities of VEGF regulation. Therefore, we undertook a direct assessment of VEGF induction in human tumors using in situ hybridization and compared its distribution with that of hypoxia, as measured by the distribution of adducts of the hypoxia marker EF5. The distribution of both markers was assessed in relationship to the distribution of blood vessels, as measured by antibodies to CD31. Our hypothesis was that VEGF mRNA and hypoxia would colocalize, assuming that detectability of the former was not limiting. Four squamous cell carcinomas, three sarcomas and one glioblastoma multiforme were studied. When VEGF mRNA signal was detectable, its maxima colocalized with regional maxima of EF5 binding. The strongest levels of both signals were sometimes adjacent to regions of tissue necrosis. However, we were unable to predict absolute levels of EF5 binding based on absolute levels of VEGF mRNA. Conversely, for all tumors studied, regions with relatively low levels of EF5 binding had relatively low or undetectable VEGF mRNA. We found moderate EF5 binding in some keratinized cells but VEGF mRNA was not expressed by these differentiated cells. The paradigm that hypoxia and VEGF expression are linked in human tumors is supported by the data presented herein. A better understanding of the biology behind VEGF expression, including its modulation by hypoxia, is important for optimizing its use as a prognostic indicator and/or modulating its presence with biologic therapies.

Expression of vascular endothelial growth factor family members in head and neck squamous cell carcinoma correlates with lymph node metastasis

BACKGROUND

The expression of vascular endothelial growth factor (VEGF)-A isoforms (121, 165, 189, 206), VEGF-B, VEGF-C and VEGF-D in both experimental and clinical models of head and neck squamous cell carcinoma (HNSCC) was determined and correlated with conventional clinicopathologic parameters, with particular reference to cervical nodal metastasis.

METHODS

The mRNA expression of VEGFs in 14 HNSCC cell lines was compared with 4 normal keratinocyte cultures and 10 fibroblast cultures using a semiquantitative reverse transcription polymerase chain reaction (RT-PCR) assay. Protein levels were determined by Western blotting and enzyme-linked immunosorbent assay (ELISA). The authors then examined the expression of VEGFs in tissues from 54 patients including histologically normal epithelium (n = 32), early invasive squamous cell carcinomas (SCCs) (n = 23), advanced primary SCCs (n = 31), and lymph node metastases (n = 27).

RESULTS

Increased levels of VEGF-A (all four isoforms) and VEGF-C were found in tumor cell lines compared with normal cells, whereas no differences in VEGF-B levels were found. VEGF-D expression, however, was lower in HNSCC cells. Studies in clinical samples showed highly significant increases in mRNA expression of all four isoforms of VEGF-A and VEGF-C in tumors versus normal epithelium. In contrast, the levels of VEGF-D were significantly decreased in tumors, and VEGF-B expression appeared similar in both normal and malignant tissues. Multivariate analysis demonstrated that an infiltrative mode of invasion and enhanced expression of VEGF-A (isoforms 121 and 165) and VEGF-C had predictive value for the presence of cervical nodal metastases.

CONCLUSIONS

Up-regulation of VEGF-A (two isoforms) and VEGF-C and down-regulation of VEGF-D have been common features in HNSCC. Thus VEGF-A and VEGF-C appeared to play a vital role in the metastatic process of HNSCC.

Tumor specific activation of the VEGF/KDR angiogenic pathway in a subset of locally advanced squamous cell head and neck carcinomas

Vascular endothelial growth factor (VEGF) and its receptors, Flt-1 and flk-1(KDR), constitute an important angiogenic pathway which, under hypoxic conditions, is up-regulated in many solid tumours. We used the monoclonal antibody 11B5, specific for recognizing VEGF expression and the 'VEGF/flk-1(KDR) complex' on tumour endothelium, to assess free VEGF protein expression and VEGF/receptor activated microvessel density (aMVD) in a series of 104 inoperable locally advanced squamous cell carcinomas of the head and neck, treated with chemo-radiotherapy. High VEGF expression in cancer cells was strongly associated with high VEGF/receptor expression in the vasculature. The high VEGF expression and the aMVD were not associated with the standard microvessel density (sMVD), as assessed with the monoclonal antibody anti-CD31 and, were not detected in normal tissue. An increased sMVD, however, was significantly related with the expression thymidine phosphorylase (TP), and also with the nuclear accumulation of the oncoprotein p53, but neither p53 nor TP was associated with VEGF expression by cancer cells or VEGF/receptor complex aMVD. In 35% of cancer cases examined, more than 20% of the microvessels assessed with anti-CD31 also expressed the VEGF/KDR complex. The vasculature of the normal head and neck mucosa did not express the VEGF/KDR complex. There was no association between VEGF expression or VEGF/receptor complex aMVD and response to chemo-radiotherapy or patient's survival. It is concluded that activation of the angiogenic pathway VEGF/flk-1(KDR) is tumor specific in a subgroup of locally advanced squamous cell carcinomas of the head and neck. Selective destruction of this type of vasculature, using immunoconjugates directed against the VEGF/receptor complex, may prove therapeutically useful for patients with a high tumoral VEGF/flk-1(KDR) activated microvessel fraction.

Expression of vascular endothelial growth factor in normal and tumour oral tissues assessed with different antibodies

Expression of vascular endothelial growth factor (VEGF) in oral tissues was assessed using different antibodies. Quantitative and topographical differences were observed between paraffin and cryostat sections. Two polyclonal antibodies (PC36, PC37) differing in their cross-reactivity with VEGF121 (not recognized by PC36), were used to stain serial cryostat sections of normal oral mucosa (n = 8) and squamous cell carcinoma (n = 7). The expression of VEGF in the epithelium was overall higher with PC37 than with PC36, the difference being significant in normal oral mucosa (p = 0.001) but not in squamous cell carcinoma samples (p = 0.094). With PC36, VEGF expression was significantly higher in squamous cell carcinoma than in normal oral mucosa specimens, whereas the opposite was true with PC37. Our results suggest that the relative levels of isoform 121 to that of 165 (and possibly others) may be different in the tissues examined, with VEGF121 preferentially expressed in normal oral mucosa. Previously published conflicting results may, therefore, be due to the presence of variable ratios of VEGF isoforms in the tissues examined, combined with differences in the cross-reactivity of the antibodies used. VEGF isoforms 121, 165 and (for the first time) 189 were detected in two frozen oral tissues by polymerase chain reaction amplification. Quantification of specific VEGF isoforms will be required in future studies concerned with the clinical value of VEGF expression.

Molecular markers in head and neck squamous cell carcinoma: their biological function and prognostic significance

Head and neck squamous cell carcinoma affects more than 500,000 people worldwide each year. Despite optimal treatment with surgery, irradiation, and chemotherapy, disease recurrence and progression remains a common and challenging oncological problem. Recently, interest has developed in identifying novel molecular markers that allow identification of those patients at increased risk for locoregional recurrence and death. This article reviews several such molecular markers studied in head and neck cancer, including p53, angiogenesis-related markers, cyclin D1, and epidermal growth factor receptor. The biological function of these markers and the potential clinical implications are discussed. The purpose of this review is to update the otolaryngologist on a rapidly emerging segment of applied translational research in our field.