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Purpose: The focal adhesion kinase (FAK) is a nonreceptor protein tyrosine kinase important in signaling between cells and their extracellular matrix. Studies have shown that FAK expression is up-regulated in several human tumors and is related to tumor progression. We recently found an increase in p125 FAK expression in human neuroblastoma cells lines and wished to determine its expression in human neuroblastoma specimens and evaluate for a possible correlation between p125 FAK expression and known prognostic factors for neuroblastoma. We hypothesized that p125 FAK expression would be up-regulated in advanced human neuroblastomas. Experimental Design: Using immunohistochemical techniques with monoclonal antibody 4.47 specific for p125 FAK expression, we analyzed 70 formalin-fixed, paraffin-embedded human neuroblastoma specimens for p125 FAK staining. In addition, real-time PCR was used to determine the abundance of FAK mRNA in 17 matched human neuroblastoma mRNA specimens. Results: FAK staining was present in 51of the 70 tumor specimens (73%). Immunohistochemical staining of p125 FAK in the ganglion-type tumor cells correlated with advanced International Neuroblastoma Staging System tumor stages and FAK mRNA abundance. In addition, p125FAK staining was significantly increased in stage IV tumors with amplification of the N-MYC oncogene. Conclusions: These novel findings provide evidence that FAK is expressed by advanced-stage neuroblastoma and provide a rationale for targeting FAK in the treatment of this tumor.Focal adhesion kinase (FAK) is a 125-kDa, nonreceptor protein tyrosine kinase that was originally isolated from embryonic chick fibroblasts transformed by v-src (1). FAK is localized to focal adhesions or contact points between cells and their extracellular matrix and has been shown to have important functions in integrin signaling, cellular motility, and cellular apoptosis. Integrins bind to FAK through their h subunits, leading to the phosphorylation of FAK (2), thereby creating a high-affinity binding site for the Src family kinases (3 -5). The FAK-Src complex activates protein kinases that eventually result in the activation of nuclear transcription factors leading to cell differentiation and growth. In addition, phosphorylation of FAK results in the binding and activation of other signaling molecules (6) resulting in decreased apoptosis and increased cellular survival.FAK has been shown to be overexpressed in several human tumors (7), with numerous reports of significantly increased FAK protein expression in primary and metastatic breast cancer (8 -11) and in colon (8, 12, 13), thyroid (14, 15), ovarian (16), and esophageal cancers (17), head and neck tumors (18), and melanoma (19). The expression of FAK mRNA has also been shown to correlate with tumor aggressiveness, with an increased abundance of FAK mRNA being seen during the progression of epithelial tumors to metastatic phenotypes (20) and also in the hepatic metastasis of human colorectal carcinomas (12). Data correlating increased fak...

Purpose-Inhibition of VEGF may effect transient "normalization" of tumor vasculature by pruning immature vessels, resulting in improved tumor perfusion and oxygenation. This may improve the efficacy of adjuvant ionizing radiation (IR). We tested this hypothesis using bevacizumab, an anti-VEGF antibody, in rhabdomyosarcoma (RMS) xenografts.Methods-Mice bearing orthotopic alveolar RMS xenografts were treated with a single dose of bevacizumab, IR, or a combination of the two on different schedules. Tumors were then evaluated for changes in microvessel density, vessel maturity, vessel permeability, intratumoral oxygenation, as well as altered growth.Results-After bevacizumab treatment, a significant decrease in tumor microvessel density and a significant increase in tumor vessel maturity, defined as the ratio of pericytes to endothelial cells, was observed, suggesting pruning of immature vessels lacking pericytes. Tumor vessel permeability was also significantly decreased and intratumoral oxygen tension increased two and five days after bevacizumab due to a transient improvement in tumor perfusion. Treatment with IR 2 or 5 days after bevacizumab resulted in the greatest antitumor activity. Conclusion-Our findings support the hypothesis that VEGF inhibition with bevacizumab transiently normalizes the dysfunctional vasculature of RMS xenografts, improving tumor oxygenation and increasing tumor sensitivity to adjuvant IR.