BrdUR abeling index (%)

FIGURE 7.7 Relative extent of bFGF-positive tumor areas as a function of overall labeling index in 10 different human SCC. Adapted from Schultz-Hectpr amd Haghayegh, Cancer Res. 53, 1444-1449 (1993).

Forootan and colleagues [144] analyzed the expression of bFGF in relation to the angiogenic degree in specimens from 51 patients affected by HNSCC of the tongue. Although bFGF was expressed heterogeneously in different regions of the tumor, in agreement with observations of others [105, 141-143], no significant correlation between raw or volume-weighted vessel counts and intensity of bFGF expression in primary carcinomas or in metastatic deposits was established. These latest data were in support of previous findings in which the high expression of bFGF in differentiated areas of 11 HNSCCs was not linked to the vascular count [145]. Contradictory results were reported in a simultaneous study conducted on 50 patients affected by oral cavity, oropharynx, larynx and hypopharynx primary HNSCC. A significantly higher expression of bFGF was found in the tumor samples compared to noral control tissues. This expresión was correlated with the mean number of microvessels, and increased vessel density in the tumors was associated with strong bFGF expression [146] (Fig. 7.8).

The ubiquitous presence of bFGF in squamous cell carcinomas of the head and neck underlines the importance of bFGF in the resulting growth of the carcinoma and its supporting stroma. However, even though the effect of bFGF on neoangiogenesis in HNSCC is still a conflicting topic, it is noteworthy that incongruities in the experimental results may arise not only from differences in the types of tumors being studied, but also in the specimens being selected, such as cultured cell lines or tumor tissues.

2. Vascular Endothelial Growth Factor

Vascular endothelial growth factor, also known as vascular permeability factor (VPF), is a multifunctional 46-kDa

200 t

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