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

Correlation Between Microvessel Density and Morphological Features in Skin Squamous Cell Carcinoma

INTRODUCTION

Abnormal angiogenesis is described in tumor growth and it facilitates its metastatic spread. Tumors with high angiogenic activity belong to the category of aggressive tumors with poor prognosis for patients. The aim of this study was to determine the blood vessels density (BVD), i.e. neovascularization at the tumor invasive front in skin squamous cell carcinoma (SCC) in order to determine its possible role in the tumor progression, and to correlate it to the blood vessels density of healthy skin and with the prognostic parameters of the TNM classification: T status, depth of tumor invasion (DI) and tumor histological grade (G), which were also correlated between each other.

MATERIAL AND METHODS

The material consisted of surgical specimens obtained from 30 patients with skin SCC, who underwent surgery. Tissue samples were routinely processed by standard paraffin technique stained by Hematoxilin-Eosin and immunohistochemically with antibodies against smooth muscle actin (SMA) and CD34. The BVD in the invasive front of the neoplasms was correlated to the healthy skin, tumor status (pT), depth of invasion and grade of histological differentiation (pG).

RESULTS

The histological analysis has shown a high statistical difference in the density of blood vessels in SCC compared to the healthy skin and statistical difference in BVD in neoplasms with different depth of invasion and different grade of differentiation. The density of neovascularzation increased with the deeper invasion and the worse differentiation.

CONCLUSION

The increased vascularization at the invasive front of SCC with deeper invasion and worse differentiation has pointed out to its possible role in neoplasm progression.

Vascular endothelial growth factor expression in invasive papillary thyroid carcinoma

BACKGROUND

The vascular endothelial growth factor (VEGF) is a major promoter of endothelial growth and migration. Some studies have shown a correlation between expression of this growth factor and prognosis in several cancers, including well-differentiated thyroid cancer.

AIM

We studied VEGF expression, local invasiveness, and other prognostic factors in papillary thyroid carcinoma (PTC) to test the hypothesis that the expression of VEGF is correlated with the degree of invasion of PTC.

PATIENTS AND METHODS

Clinical and pathological data of 76 patients with PTC were retrospectively reviewed. Group 1 consisted of patients with gross locally invasive tumors, group 2 consisted of patients with only invasion of the thyroid capsule, and group 3 consisted of patients with noninvasive PTC.

RESULTS

VEGF expression was noted within the tumor in all groups of PTC patients but was absent in the surrounding normal tissue. Older patients had higher expression of VEGF than younger patients. The age of patients with strong reaction to VEGF was 46 +/- 14 (mean +/- standard deviation), and that in patients with a weaker reaction was 39 +/- 16 (p < 0.05). Only 20% of patients with a follicular variant of PTC had a strong reaction to VEGF compared with 68% of patients with classical PTC (p < 0.01).

CONCLUSIONS

VEGF expression appears to be an early event in the development of PTC. Whether VEGF expression promotes the progression of PTC is not known, but the answer to this question may be important in view of its greater expression in older patients, a group whose prognosis in PTC is worse.

Vascular Endothelial Growth Factor Expression Predicts Outcome after Primary Radiotherapy for Head and Neck Squamous Cell Cancer

AIMS

To establish whether the expression of vascular endothelial growth factors (VEGFs) predicts prognosis in patients treated with primary radiotherapy for cancers of the upper aerodigestive tract.

MATERIALS AND METHODS

A retrospective analysis was undertaken of VEGF and VEGF-D expression in tumour tissue in pre-treatment biopsies from 27 patients who had been treated with primary radiotherapy for stage II-IV squamous head and neck carcinomas. Serial sections (4 microm) were cut from formalin-fixed, paraffin-embedded specimens and stained with monoclonal antibodies using standard immunoperoxidase methods. Two independent investigators assessed the staining intensity in a randomised, blind manner. Both negative and positive controls (placenta and/or tonsil) were included in the staining procedure. All patients were followed for a minimum of 5 years, or until death. Local control and overall survival were taken as end points for the comparative analysis between patients whose tumours expressed low levels and those that expressed high levels of the two growth factors. Comparisons were made using the Log-rank test with Kaplan-Meier actuarial survival analysis.

RESULTS

In patients with tumours expressing low levels of VEGF, 5-year local control was seen in 75% compared with 18% for those with high levels; overall survival was 75 and 23%, respectively. For those with low levels of VEGF-D, 5-year local control was 64% compared with 17% for those with high levels; overall survival was 58 and 20%, respectively.

CONCLUSION

Our results suggest that the expression of endothelial growth factors in squamous head and neck cancers may predict outcome after radiotherapy.

Hypoxia-activated tumor pathways of angiogenesis and pH regulation independent of anemia in head-and-neck cancer

PURPOSE

Anemia is considered a major factor that counteracts the efficacy of radiotherapy, presumably because of reduced oxygen availability that leads to tumor hypoxia. Nevertheless, anemia is not the only factor defining oxygen availability, because a poor and/or immature vascular network may prevent blood flow and tumor oxygenation. Furthermore, the ability of tumors to upregulate hypoxia-regulated molecular pathways may affect radiosensitivity by mechanisms independent of the traditional concept of "oxygen effect."

METHODS AND MATERIALS

In this study, we investigated whether the preoperative blood hemoglobin levels affect the activation status of hypoxia/angiogenic pathways (hypoxia inducible factors [HIF1 alpha and HIF2 alpha], carbonic anhydrase 9, differentiated embryo-chondrocyte protein, vascular endothelial growth factor, and microvessel density), in squamous cell head-and-neck cancer.

RESULTS

Hypoxia/angiogenesis pathways were equally activated in tumors, independent of the patient's hemoglobin levels. The expression of HIF alphas was associated with microvessel density (p = 0.01).

CONCLUSION

In the present study, we failed to show that a patient's anemia is a main contributor to the activation of hypoxia-regulated molecular pathways in squamous cell head-and-neck cancer. Impaired intratumoral blood flow or tumor-related gene/protein pathologic features may account for this finding. Targeting the hypoxia-regulated molecular cascade emerged as a complementary radiosensitization strategy for a large group of patients with hypoxic tumors, who are unlikely to benefit from conventional approaches aiming to improve intratumoral oxygen delivery through anemia correction.

The vascular network of tumours--what is it not for?

It is becoming almost a dogma that tumours cannot grow beyond 1-2 mm(3) unless they are supported by a rich vascular supply 1. It is true that tumours promote angiogenesis and that highly vascularized carcinomas have, in general, a more aggressive clinical course than carcinomas of low vascularization 23. However, a study of intratumoral angiogenesis reveals that the newly formed vessels are commonly deprived of those structural qualities that would allow them to perform an optimal oxygenation function 3. Thus, most tumours, irrespective of their angiogenic status, behave as if they were 'hypoxic', urging (via angiogenic mediators) for, what would look paradoxical at first sight, more defective angiogenesis. It is hypothesized that tumour cells can grow into solid neoplasms by exploiting the host's pre-existing vessels, without the need for new blood vessel formation. Neovascularization, however, may be important for tumours with an exophytic pattern of growth as these, by their very nature, lose the host's sheltering stroma. Shifting to anaerobic glycolysis and activation of anti-apoptotic pathways are complementary mechanisms for tumour cell survival and growth. Besides, continuous and indiscriminate production of a defective vascular network ensures an increased metastatic potential since the newly formed intratumoral vessels, simulating venular-like spaces, are easily permeable to tumour cells, facilitating metastases.

The angiogenic "vascular endothelial growth factor/flk-1(KDR) receptor" pathway in patients with endometrial carcinoma: prognostic and therapeutic implications

BACKGROUND

Vascular endothelial growth factor (VEGF) is an important endothelial cell mitogen associated with increased angiogenesis and aggressive tumor behavior. Its stimulating effect on endothelial cells basically is dependent on the presence of specific VEGF receptors, such as the flk-1(KDR) receptor. This study investigates the roles of VEGF and of a functionally intact angiogenic pathway, "VEGF/flk-1(KDR)," in patients with endometrial carcinoma and their significance in prognosis and therapy.

METHODS

A series of 121 endometrial carcinomas were studied. The expression of VEGF by endometrial tumor cells was assessed using the monoclonal antibody (MoAb) VG1. VEGF/KDR complexes on tumor endothelium or activated microvessel density (aMVD) were identified using the MoAb 11B5. In addition, the standard microvessel density (sMVD) was assessed with anti-CD31. In all tumors, the alkaline phosphatase/antialkaline phosphatase technique was employed. A Fisher exact test or an unpaired, two-tailed t test was used for testing correlations between categoric tumor variables, whereas a log-rank test was used to determine statistical differences between life tables. A Cox proportional hazards model was used to assess the effect of tumor variables on overall survival.

RESULTS

Cytoplasmic VEGF expression in > 50% of tumor cells was associated significantly with aMVD (P < 0.0001) and with sMVD (P < 0.003). In univariate survival analysis, VEGF (P = 0.0002), aMVD (P = 0.001), and sMVD (P = 0.0009) were significant prognostic variables. Equally important were the histologic parameters tumor type (P = 0.03), tumor grade (P = 0.003), and disease stage (P < 0.0001). In multivariate analysis, disease stage was the most important independent prognostic factor (P < 0.0001), followed by VEGF/KDR (P < 0.01), and VEGF (P < 0.04). Furthermore, VEGF and VEGF/KDR were the only independent prognostic variables for patients with Stage I endometrioid adenocarcinoma.

CONCLUSIONS

sMVD and the angiogenic factor VEGF are important indicators of a poor prognosis in patients with endometrial carcinoma. VEGF/KDR complexes define a subgroup of patients with endometrial carcinoma with an even worse prognosis.