Angiogenesis in the development of head and neck cancer and its inhibition by chemopreventive agents

Comprehensive analysis of angiogenesis subtype of squamous cell carcinoma

Background

Squamous cell carcinoma (SCC) is a disease with distinct management complexities as it displays a remarkably heterogeneous molecular subtype. However, the landscape of angiogenesis for SCC is not fully investigated.

Method and materials

The angiogenesis-related subtypes of SCC were established by using the ConsensusClusterPlus package based on angiogenesis-related genes and TCGA data. We analyzed the alteration of genes and miRNAs as well as pathways associated with angiogenesis subtypes. Next, the regulation network, the correlation with genomic characteristics, immune microenvironment, and clinical features of the angiogenesis subtypes were further investigated. Finally, the prognostic impact of the angiogenesis-related subtypes for SCC was also analyzed.

Results

A total of 1368 SCC samples were included in this study. Two angiogenesis subtypes were then identified based on the one hundred and sixty-three angiogenesis-related genes with subtype1 (angiogenesis subtype) of 951 SCC patients and subtype2 (non-angiogenesis subtype) of 417 SCC. GSEA revealed that angiogenesis and epithelial-mesenchymal transition, inflammatory response, and hypoxia were enriched in the angiogenesis subtype. Eight of the 15 immune checkpoints (ADORA2A, BTLA, CD276, CYBB, HAVCR2, SIGLEC7, SIGLEC9, and VTCN1) were significantly upregulated while C10orf54 were significantly downregulated in the angiogenesis subtype. The survival analysis revealed that the patients in the angiogenesis subtype have poorer survival outcomes than those in the non-angiogenesis subtype (P = 0.017 for disease-free interval and P = 0.00013 for overall survival).

Conclusion

Our analysis revealed a novel angiogenesis subtype classification in SCC and provides new insights into a hallmark of SCC progression.

Ras-Mediated Activation of NF-κB and DNA Damage Response in Carcinogenesis

Cancer is a multi-step process during which cells acquire mutations that eventually lead to uncontrolled cell growth and division and evasion of programmed cell death. The oncogenes such as Ras and c-Myc may be responsible in all three major stages of cancer i.e., early, intermediate, and late. The NF-κB has been shown to control the expression of genes linked with tumor pathways such as chronic inflammation, tumor cell survival, anti-apoptosis, proliferation, invasion, and angiogenesis. In the last few decades, various biomarker pathways have been identified that play a critical role in carcinogenesis such as Ras, NF-κB and DNA damage.

Histomorphometric Analysis of Angiogenesis using CD31 Immunomarker and Mast Cell Density in Oral Premalignant and Malignant Lesions: A Pilot Study

INTRODUCTION

Mast cells have been implicated in promoting angiogenesis in malignant tumors of lung, oesophagus and breast, but there are few studies on Oral Squamous Cell Carcinomas (OSCC). Most oral squamous cell carcinomas arise from pre-existing precancerous lesions exhibiting epithelial dysplasia.

AIM

The present pilot study attempts to compare Mast Cell Density (MCD), Microvessel Density (MVD), Microvessel Area (MVA) histomorphometrically between normal buccal mucosa, severe epithelial dysplasia and OSCC and to correlate the role of mast cells and angiogenesis in tumor progression.

MATERIAL AND METHODS

The retrospective study was conducted on eight cases of OSCC, eight cases of severe epithelial dysplasia and five cases of normal buccal mucosa. Immunohistochemical staining with anti CD-31, to demonstrate angiogenesis and toluidine blue staining for mast cells were employed. MVA, MVD and MCD were calculated using the measurement tools of the image analysis software and compared between the groups. One way ANOVA (Analysis of Variance) was used for comparing the parameter for multiple groups followed by Games Howell test. To assess the relationship between micro vessel density and mast cell density, Karl Pearson's correlation was used.

RESULTS

MCD and MVD increased with disease progression and were statistically higher in OSCC than in severe epithelial dysplasia and normal buccal mucosa (p<0.001). MVA increased from normal to severe dysplasia and decreased from dysplasia to OSCC, may be due to revascularization of tumor tissue. A positive correlation was observed between MCD and MVD in OSCC and dysplasia, though were not statistically significant.

CONCLUSION

These findings suggest that mast cells may up regulate angiogenesis in OSCC. MCD and MVD may be used as indicators for disease progression.

Immunohistochemical Expression of CD105 and TGF-β1 in Oral Squamous Cell Carcinoma and Adjacent Apparently Normal Oral Mucosa and its Correlation With Clinicopathologic Features

Angiogenesis in oral squamous cell carcinomas (OSCC) is essential for its growth, invasion, and metastasis. This entails a shift in the balance between proangiogenic and antiangiogenic factors. CD105 and TGF-β1 are 2 such proangiogenic factors wherein CD105 exerts its angiogenic effect by binding to and modulating the TGF-β1 pathway. A total of 50 resected specimens of OSCC were considered. One tissue specimen was taken from tumor proper and another specimen from adjacent apparently normal mucosa (AANM). Both tissues were immunohistochemically stained using CD105 and TGF-β1 antibodies. The expression of each antibody was individually assessed and then compared. Pearson χ test was used for statistical comparison of expression. CD105 was significantly expressed in OSCC as compared with AANM and also correlated with increasing TNM stage. The mean microvessel density was higher in OSCC. TGF-β1 was significantly expressed in epithelium of OSCC as compared with AANM. On comparing expression of TGF-β1 and CD105, 79.54% of endothelial cells expressed positivity for both molecules. Both CD105 and TGF-β1 were increased in OSCC, although based on our results CD105 alone can be used as a prognostic marker. On the basis of immunohistochemical expression of CD105 and TGF-β1 in endothelial cells, our results demonstrate that CD105 acts as one of the receptors of TGF-β1 on endothelial cells and induces the angiogenic pathway in OSCC.

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.

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.

Oncoapoptotic signaling and deregulated target genes in cancers: special reference to oral cancer

Cancer is a class of diseases characterized by uncontrolled cell growth. The development of cancer takes place in a multi-step process during which cells acquire a series of mutations that eventually lead to unrestrained cell growth and division, inhibition of cell differentiation, and evasion of cell death. Dysregulation of oncoapoptotic genes, growth factors, receptors and their downstream signaling pathway components represent a central driving force in tumor development. The detailed studies of signal transduction pathways for mechanisms of cell growth and apoptosis have significantly advanced our understanding of human cancers, subsequently leading to more effective treatments. Oral squamous cell carcinoma represents a classic example of multi-stage carcinogenesis. It gradually evolves through transitional precursor lesions from normal epithelium to a full-blown metastatic phenotype. Genetic alterations in many genes encoding crucial proteins, which regulate cell proliferation, differentiation, survival and apoptosis, have been implicated in oral cancer. As like other solid tumors, in oral cancer these genes include the ones coding for cell cycle regulators or oncoproteins (e.g. Ras, Myc, cyclins, CDKs, and CKIs), tumor suppressors (e.g. p53 and pRb), pro-survival proteins (e.g. telomerase, growth factors or their receptors), anti-apoptotic proteins (e.g. Bcl2 family, IAPs, and NF-kB), pro-apoptotic proteins (e.g. Bax and BH-3 family, Fas, TNF-R, and caspases), and the genes encoding key transcription factors or elements for signal transduction leading to cell growth and apoptosis. Here we discuss the current knowledge of oncoapoptotic regulation in human cancers with special reference to oral cancers.

Improved edge delineation using a low-flow and delayed-phase contrast-enhanced protocol for computed tomography imaging of oral cavity and oropharyngeal malignancies

AIM

To determine whether contrast-enhanced computed tomography (CT) performed with a high flow rate and short delay protocol or a lower flow rate and longer delay protocol resulted in better enhancement of the oral cavity and oropharyngeal tumour and tumour edge delineation.

MATERIALS AND METHODS

Patients with squamous cell carcinomas of the upper aerodigestive tract (UAT) who underwent contrast-enhanced CT using 100 ml contrast material with 300 mg iodine/ml were selected for this comparison study. The protocols studied used a high flow rate and short scan delay (2 ml/s and 50 s) and a lower flow rate and longer delay (1 ml/s and 100 s). Contrast enhancement by radiodensity in Hounsfield units of the tumour site, poorest and clearest tumour boundaries and contralateral lateral pterygoid muscle were measured using a region of interest tool. A t-test statistical analysis was used to compare both protocols.

RESULTS

The lower flow and longer delay protocol maximized contrast differences at both the poorest and clearest definition boundaries of the tumour (p ≤ 0.01 and p ≤ 0.05, respectively) and the pterygoid muscle (p ≤ 0.01). There was no significant difference in contrast enhancement within the central homogeneous tumour site.

CONCLUSION

A lower flow and longer delay protocol (1 ml/s and 100 s) provided better enhancement of the delineation of the tumour edge and surrounding musculature than a high flow rate and short delay protocol (2 ml/s and 50 s). Both protocols achieved similar central tumour enhancement.

Parylene peel-off arrays to probe the role of cell-cell interactions in tumour angiogenesis

Microenvironmental conditions impact tumour angiogenesis, but the role of cell-cell interactions in modulating the angiogenic capability of tumour cells is not well understood. We have microfabricated a peel-off cell-culture array (PeelArray) chip to spatiotemporally control interactions between tumour cells in a large array format and to analyse angiogenic factor secretion in response to these conditions. The PeelArray chip consists of a polyethylene glycol (PEG) treated glass coverslip coated with a parylene-C template that can be easily peeled off to selectively micropattern biomolecules and cells. We have designed the PeelArray chip to reproducibly deposit large uniform arrays of isolated single cells or isolated cell clusters on fibronectin features of defined surface areas. We have utilised this microfabricated culture system to study the secretion of angiogenic factors by tumour cells, in the presence or absence of cell-cell contact as controlled by micropatterning. Our results indicate that cell-cell interactions play a synergistic role in regulating the expression of angiogenic factors (i.e., vascular endothelial growth factor [VEGF] and interleukin-8 [IL-8]) in various cancer cell lines, independent of other more complex microenvironmental cues (e.g. hypoxia). Our PeelArray chip is a simple and adaptable micropatterning method that enables quantitative profiling of protein secretions and hence, a better understanding of the mechanisms by which cell-cell interactions regulate tumour cell behaviour and angiogenesis.

Angiogenesis in pre-malignant conditions

Angiogenesis is an essential process involved in the normal growth and differentiation. In its defective and excessive form, angiogenesis is a crucial event in the progression of many human diseases. Excessive angiogenesis was largely investigated in psoriasis, arthritis, diabetic retinopathy and malignant tumours. Soon after the discovery of angiogenic factors and their inhibitors, the angiogenesis jumped from the experimental studies to clinical application. Tumour-associated angiogenesis is nowadays considered as a priority in oncology based on numerous evidences that showed a significant reduction in tumour growth following anti-angiogenic therapy. However, few data are available on pre-malignant conditions. First evidences on angiogenesis in pre-malignant lesions came from the evaluation of microvessel density (MVD). MVD was found to be significantly increased in a relatively large spectrum of pre-malignant squamous cell lesions, such as in the oral mucosa, skin, uterine cervix, vulva and anal canal. For many of them, a correlation was found between MVD and the expression of vascular endothelial growth factor (VEGF). Based on these data, it was suggested that tumour angiogenesis is not necessarily a characteristic of invasive tumour, but may be an early event during tumourigenesis. Additional evidences came from pre-malignant lesions of glandular epithelia, in which the angiogenic switch was demonstrated by the immunohistochemical expression of VEGF in gastric metaplasia and dysplasia, in atypical adenoma of the colon, atypical hyperplasia and carcinoma in situ of the breast and others. Actually, there are convincing evidences for an active angiogenesis in many cases with pre-malignant conditions, and this supports a more accurate evaluation of different chemopreventive agents.

ABT-510 is an effective chemopreventive agent in the mouse 4-nitroquinoline 1-oxide model of oral carcinogenesis

Despite numerous advances, the 5-year survival rate for head and neck squamous cell cancer (HNSCC) has remained largely unchanged. This poor outcome is due to several variables, including the development of multiple primary tumors. Therefore, it is essential to supplement early detection with preventive strategies. Using the 4-nitroquinoline 1-oxide (4-NQO) mouse model, we sought to define an appropriate dose and duration of administration that would predict the histologic timeline of HNSCC progression. Additionally, we sought to determine the timing of the onset of the angiogenic phenotype. Finally, using ABT-510 as a proof-of-principle drug, we tested the hypothesis that inhibitors of angiogenesis can slow/delay the development of HNSCC. We determined that 8 weeks of 100 microg/mL 4-NQO in the drinking water was the optimal dosage and duration to cause a sufficient incidence of hyperkeratoses, dysplasias, and HNSCC over a period of 32 weeks with minimal morbidity and mortality. Increased microvessel density and vascular endothelial growth factor expression in hyperkeratotic lesions provided evidence that the initiation of the angiogenic phenotype occurred before the development of dysplasia. Importantly, ABT-510 significantly decreased the overall incidence of HNSCC from 37.3% to 20.3% (P = 0.021) as well as the combined incidence of dysplasia and HNSCC from 82.7% to 50.6% (P < 0.001). These findings suggest that our refinement of the 4-NQO model allows for the investigation of the histologic, molecular, and biological alterations that occur during the premalignant phase of HNSCC. In addition, these data support the hypothesis that inhibitors of angiogenesis may be promising chemopreventive agents.

Cancer cell angiogenic capability is regulated by 3D culture and integrin engagement

Three-dimensional culture alters cancer cell signaling; however, the underlying mechanisms and importance of these changes on tumor vascularization remain unclear. A hydrogel system was used to examine the role of the transition from 2D to 3D culture, with and without integrin engagement, on cancer cell angiogenic capability. Three-dimensional culture recreated tumor microenvironmental cues and led to enhanced interleukin 8 (IL-8) secretion that depended on integrin engagement with adhesion peptides coupled to the polymer. In contrast, vascular endothelial growth factor (VEGF) secretion was unaffected by 3D culture with or without substrate adhesion. IL-8 diffused greater distances and was present in higher concentrations in the systemic circulation, relative to VEGF. Implantation of a polymeric IL-8 delivery system into GFP bone marrow-transplanted mice revealed that localized IL-8 up-regulation was critical to both the local and systemic control of tumor vascularization in vivo. In summary, 3D integrin engagement within tumor microenvironments regulates cancer cell angiogenic signaling, and controlled local and systemic blockade of both IL-8 and VEGF signaling may improve antiangiogenic therapies.

Effect of PTK/ZK on the angiogenic switch in head and neck tumors

Transformation of small avascular masses of tumor cells into rapidly progressive cancers is triggered by the angiogenic switch, a process that involves vascular endothelial growth factor (VEGF) signaling. We have shown that VEGF enhances the survival and angiogenic potential of endothelial cells by activating the Bcl-2-CXCL8 signaling axis. The purpose of this study was to evaluate the effect of a small-molecule inhibitor of VEGF receptors (PTK/ZK) on the initial stages of head and neck tumor angiogenesis. In vitro, PTK/ZK blocked head and neck tumor cell (OSCC3 or UM-SCC-17B)-induced Bcl-2 and CXCL8 expression in endothelial cells. Oral administration of PTK/ZK decreased xenograft head and neck tumor microvessel density, and inhibited Bcl-2 and CXCL8 expression in tumor-associated endothelial cells. Analysis of these data demonstrates that PTK/ZK blocks downstream targets of VEGF signaling in endothelial cells, and suggests that PTK/ZK may inhibit the angiogenic switch in head and neck tumors.

Angiogenic heterogeneity in head and neck squamous cell carcinoma: biological and therapeutic implications

The literature contains numerous references describing heterogeneity for tumor phenotypes including cell proliferation, invasiveness, metastatic potential, and response to therapies. However, data regarding angiogenic heterogeneity are limited. In this study, we investigated the degree of intertumoral angiogenic heterogeneity present in head and neck squamous cell carcinomas (HNSCC). In addition, we investigated the biological relevance that this heterogeneity may have in the context of cytokine directed antiangiogenic therapy. Keratinocytes were harvested from HNSCC specimens using laser capture microdissection (LCM). Gene expression profiling of the RNA extracted from these specimens demonstrated variability in the expression of angiogenesis-related genes. Hierarchical clustering and principal component analyses (PCA) demonstrated the presence of unique patient clusters, suggesting that there may be two potentially distinct pathways by which HNSCC induce angiogenesis. Immunohistochemistry for VEGF, IL-8/CXCL8, HGF, and FGF-2, cytokines that play functional roles in HNSCC angiogenesis was performed on the original patient samples as well as a larger panel of normal, dysplastic and HNSCC specimens to validate the heterogeneous expression observed in the gene expression profiling studies. Finally, the therapeutic response of HNSCC tumor xenografts to anti-VEGF therapy was found to be dependent on the amount of VEGF produced by the tumor cells. These findings support the hypothesis of intertumoral angiogenic heterogeneity. They imply that there are differences with regard to the specific molecular mechanisms by which individual tumors within the same histological type induce angiogenesis. Moreover, they demonstrate the need for a more in-depth understanding of the variability of the angiogenic phenotype within a given type of neoplasm when designing cytokine targeted antiangiogenic therapies. Finally, they suggest that studies in conjunction with the ongoing clinical trials that explore the correlation between target expression and clinical outcome are warranted.

Suppression of the tumorigenic phenotype in human oral squamous cell carcinoma cells by an ethanol extract derived from freeze-dried black raspberries

Despite focused efforts to improve therapy, 5-yr survival rates for persons with advanced-stage oral squamous cell carcinoma (SCC) remain discouragingly low. Clearly, early detection combined with strategies for local intervention, such as chemoprevention prior to SCC development, could dramatically improve clinical outcomes. Previously conducted oral cavity human chemoprevention trials, however, have provided mixed results. Although some therapies showed efficacy, they were often accompanied by either significant toxicities or circulating antiadenoviral antibodies. It is clearly apparent that identification of nontoxic, effective treatments is essential to prevent malignant transformation of oral epithelial dysplasias. This study employed cell lines isolated from human oral SCC tumors to investigate the effects of a freeze-dried black raspberry ethanol extract (RO-ET) on cellular growth characteristics often associated with a transformed phenotype such as sustained proliferation, induction of angiogenesis, and production of high levels of reactive species. Our results demonstrate that RO-ET suppresses cell proliferation without perturbing viability, inhibits translation of the complete angiogenic cytokine vascular endothelial growth factor, suppresses nitric oxide synthase activity, and induces both apoptosis and terminal differentiation. These data imply that RO-ET is a promising candidate for use as a chemopreventive agent in persons with oral epithelial dysplasia.

Computed tomography perfusion of squamous cell carcinoma of the upper aerodigestive tract. Initial results

OBJECTIVE

To define the computed tomography (CT) perfusion characteristics of head and neck squamous cell carcinoma.

METHODS

Fourteen consecutive patients with untreated squamous cell cancers of head and neck underwent CT of the head and neck along with CT perfusion imaging through the primary site. For the perfusion studies, CT density changes in blood and tissues were kinetically analyzed using the commercially available CT Perfusion 2 software (General Electric Medical Systems. Milwaukee, WI) on a GE Advantage Windows workstation. This yielded parameter maps of fractional tissue blood volume (mL/100 g), blood flow (mL x 100 g(-1) x min(-1)), mean transit time (s), and microvascular permeability surface area product (mL x 100 g(-1) x min(-1)). One head and neck radiologist analyzed perfusion data. Regions of interest (ROI) were placed over the primary tumor site, tongue base, and adjacent muscle groups. The average values of tissue blood volume (BV), blood flow (BF), mean transit time (MTT), and capillary permeability surface area product (CP) were then calculated for the tumor and compared with the average values for the tongue base and adjacent musculature. To determine a statistically significant difference between the tumor and muscle parameters, the Wilcoxon sign test, a nonparametric test for paired data, was employed.

RESULTS

The average values of CP, BF, and BV were higher in primary tumor (41.9, 132.9, 6.2, respectively) than in tongue base or adjacent muscular structures. The MTT was reduced in primary tumors (4.0) compared with adjacent normal structures. The above differences were statistically significant (P<0.05).

CONCLUSIONS

We obtained baseline perfusion data for head and neck squamous cell cancers and compared it with adjacent normal structures. Our initial results suggest that CT perfusion parameters (CP, BF, BV, and MTT) can be used to help differentiate head and neck squamous cell carcinoma (SCCA) from adjacent normal tissue.

The effectiveness of community-based visual screening and utility of adjunctive diagnostic aids in the early detection of oral cancer

A systematic review of community-based oral cancer screening programmes published between 1966 and March 2002 was undertaken. Data relating to study design, sampling and characteristics of the study group, interventions, and reported outcomes and diagnostic value of visual screening or adjunctive diagnostic aids were abstracted from 36 articles meeting inclusion and exclusion criteria. From these reports, there is insufficient evidence to demonstrate the effectiveness of community-based oral cancer visual screening in enhancing the early detection of oral cancer, due to small effect size. While the evidence is fair to support use of toluidine blue as an aid in diagnosis of oral cancer, there is insufficient evidence to determine whether the use of this or other adjunctive techniques will increase the detection of oral malignancies in community screening programmes. Targeted clinical examination of high-risk individuals may be more effective than mass screening in facilitating early detection of oral cancers.

Retinoic acid modulates the ability of macrophages to participate in the induction of the angiogenic phenotype in head and neck squamous cell carcinoma

Angiogenesis, an essential step in the development of neoplasia, is a complex process that involves the interaction of tumor cells with stromal cells. Tumor-associated macrophages (TAMs) can participate in the induction of angiogenesis and are of prognostic value in some neoplasms. Specimens from head and neck squamous cell carcinomas (HNSCC) often contain large numbers of TAMs. In addition, experimental evidence has demonstrated that HNSCC tumor cells can attract and activate macrophages to participate in the expression of the angiogenic phenotype. These findings suggest that antiangiogenic therapies for HNSCC must include strategies that will block the recruitment of macrophages into the tumor microenvironment. We investigated the ability of retinoic acid (RA) to modulate the ability of tumor cells to recruit and activate monocytes for participation in tumor angiogenesis. Owing to a decrease in the secretion of MCP-1 and transforming growth factor-beta 1 (TGF-beta 1), tumor cells treated with RA were unable to induce peripheral blood monocyte (PBM) chemotaxis. Also, as a result of the decrease in TGF-beta 1 secretion, RA-treated tumor cells were unable to activate macrophages for secretion of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8). In addition to its affects on tumor cells, RA also directly altered the ability of monocytes to participate in the tumor angiogenesis process. PBM exposed to RA were unable to migrate toward inducers of PBM such as MCP-1 and TGF-beta 1. Finally, RA decreased the ability of tumor-activated macrophages to secrete IL-8 and VEGF. These data demonstrate alternative mechanisms by which RA may modulate angiogenesis in the tumor microenvironment. In addition, it underscores the necessity to develop antiangiogenic treatment protocols that can block each of the ways in which new blood vessel growth is induced in tumor microenvironments.

Computer-assisted image analysis of neovascularization in thyroid neoplasms from dogs

OBJECTIVE

To develop a computer-assisted image analysis procedure for quantitation of neovascularization in formalin-fixed paraffin-embedded specimens of thyroid gland tissue from dogs with and without thyroid gland neoplasia.

SAMPLE POPULATION

47 thyroid gland carcinomas, 8 thyroid gland adenomas, and 8 specimens of thyroid tissue from dogs without thyroid gland abnormalities (normal).

PROCEDURE

Serial tissue sections were prepared and stained with antibodies against human CD31 or factor VIII-related antigen (factor VIII-rag). The areas of highest vascularity were identified in CD31-stained sections, and corresponding areas were then identified in factor VIII-rag-stained sections. Image analysis was used to calculate the total vascular density in each section, and neovascularization, expressed as a percentage, was determined as the absolute value of the total vascular density derived from factor VIII-rag-stained sections minus the vascular density derived from CD31-stained sections.

RESULTS

Mean vascular density of thyroid gland carcinomas derived from CD31-stained sections was significantly greater than density derived from factor VII I-rag-stained sections. This incremental difference was presumed to represent degree of neovascularization. However, significant differences were not detected between vascular densities derived from CD31 and factor VIII-rag-stained sections for either normal thyroid gland tissue or thyroid gland adenomas. No significant correlations were found between vascular density in thyroid gland carcinomas and survival time following surgery.

CONCLUSION AND CLINICAL RELEVANCE

A computer-assisted image analysis method was developed for quantifying neovascularization in thyroid gland tumors of dogs. This method may allow identification of dogs with tumors that are most likely to respond to treatment with novel antiangiogenesis agents.

Advanced diagnostic methods in oral and maxillofacial pathology. Part II: immunohistochemical and immunofluorescent methods

The practice of pathology is currently undergoing significant change, in large part due to advances in the analysis of DNA, RNA, and proteins in tissues. These advances have permitted improved biologic insights into many developmental, inflammatory, metabolic, infectious, and neoplastic diseases. Moreover, molecular analysis has also led to improvements in the accuracy of disease diagnosis and classification. It is likely that, in the future, these methods will increasingly enter into the day-to-day diagnosis and management of patients. The pathologist will continue to play a fundamental role in diagnosis and will likely be in a pivotal position to guide the implementation and interpretation of these tests as they move from the research laboratory into diagnostic pathology. The purpose of this 2-part series is to provide an overview of the principles and applications of current molecular biologic and immunologic tests. In Part I, the biologic fundamentals of DNA, RNA, and proteins and methods that are currently available or likely to become available to the pathologist in the next several years for their isolation and analysis in tissue biopsies were discussed. In Part II, advances in immunohistochemistry and immunofluorescence methods and their application to modern diagnostic pathology are reviewed.

Paracrine angiogenic loop between head-and-neck squamous-cell carcinomas and macrophages

Angiogenesis, an essential step in the development of neoplasia, is a complex process that involves the interaction of tumor cells with stromal cells. Tumor-associated macrophages (TAMs) can participate in the induction of tumor angiogenesis and are thought to be of prognostic value in some neoplasms. We have investigated how macrophages contribute to angiogenesis in head-and-neck squamous-cell carcinoma (HNSCC) and have found that tumor cells attract monocytes and activate them to secrete angiogenic factors. The attraction of macrophages was due to the secretion of monocyte chemotactic protein-1 and TGF-beta1 by tumor cells, while tumor production of TGF-beta1 was responsible for activating macrophages. In addition, activated macrophages produced cytokines that acted in a paracrine fashion by secreting both TNF-alpha and IL-1, which in turn stimulated tumor cells to secrete increased levels of IL-8 and VEGF. These data demonstrate that TAMs play an important role in the in vivo induction of angiogenesis in HNSCC and suggest that anti-angiogenic therapies for HNSCC and perhaps other neoplasms must include strategies that will block the ability of tumor cells to recruit macrophages into the tumor micro-environment.

Pulsed-dye laser and retinoic acid delay progression of oral squamous cell carcinoma: a murine model

OBJECTIVES/HYPOTHESIS

This study examined the role of the pulsed-dye laser (PDL) at 585 nm coupled with retinoic acid at therapeutic (5.0 mg/kg) and nontherapeutic (0.5 mg/kg) doses to delay the progression of cancer with a two-hit approach. The existing vasculature is selectively targeted by the laser, whereas retinoic acid inhibits future angiogenesis.

STUDY DESIGN

Randomized, prospective study in a murine model.

METHODS

Twenty-five athymic nude mice were inoculated with oral squamous cell cancers on six flank sites and randomly divided into five groups: 1) control subjects, 2) treatment with 0.5 mg/kg retinoic acid (RA 0.5), 3) treatment with 5.0 mg/kg retinoic acid (RA 5.0), 4) treatment with RA 0.5 + PDL, and 5) treatment with RA 5.0 + PDL. The PDL groups received irradiation after inoculation. The retinoic acid was administered daily. The tumors were counted and measured for 14 days.

RESULTS

The control group developed visible tumors in 50% of the inoculation sites at 3 days compared with 3 days (RA 0.5) and 4 days (RA 5.0) for the retinoic acid groups and 9 days (RA 0.5 + PDL) and 10 days (RA 5.0 + PDL) for the laser treatment groups. There was no tumor growth until day 7 in the RA 5.0 + PDL group. The tumor volume was statistically different between the treatment groups.

CONCLUSION

This study demonstrated the superiority of a single treatment with the PDL coupled with retinoic acid to delay the progression of cancer when compared with treatment with retinoic acid alone, thus introducing a novel strategy in cancer control.

Genetic mechanisms in squamous cell carcinoma of the head and neck

This review aims to explore the genetic mechanisms involved in the development of squamous cell carcinoma of the head and neck (SCCHN). The epidemiology of SCCHN is complex due to the multiple molecular events that occur and the number of environmental agents to which individuals may have been exposed. It is clear that the major aetiological agents are tobacco and alcohol but it is also becoming apparent that other factors such as an underlying genetic susceptibility may also be important. An inherited predisposition may occur as a consequence of increased mutagen sensitivity, inability to metabolize carcinogens or pro-carcinogens or repair DNA damage. The current advances in understanding of the roles of somatic mutations, viral infection and angiogenesis are discussed. The final part of this review focuses on the way in which molecular changes may be used for prevention, early diagnosis and treatment of SCCHN.