Different fibronectin (FN) isoforms are generated by the alternative splicing of 3 regions (ED-A, ED-B and IIICS) of the primary transcript. The FN isoform containing the ED-B sequence, a complete type-III-homology repeat, while having extremely restricted distribution in normal adult tissues, reveals high expression in fetal and tumor tissues. Using the monoclonal antibody (MAb) BC-I, specific for the FN isoform containing the ED-B sequence (B+.FN), we demonstrated here, using immunohistochemical techniques, that while this FN isoform is undetectable in mature vessels, it is highly expressed during angiogenesis both in neoplastic and in normal tissues, as in the case of the functional layer of endometrium during the proliferative phase. B+.FN is thus a marker for the formation of new vessels, and the BC-I MAb may be a useful reagent for evaluating the level of the angiogenetic process in different neoplasms.

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Purpose: Hypothalamic or locally produced growth factors and cytokines control pituitary development, functioning, and cell division. We evaluated the expression of the chemokine stromal cell^derived factor 1 (SDF1) and its receptor CXCR4 in human pituitary adenomas and normal pituitary tissues and their role in cell proliferation. Experimental Design: The expression of SDF1 and CXCR4 in 65 human pituitary adenomas and 4 human normal pituitaries was determined by reverse transcription-PCR, immunohistochemistry, and confocal immunofluorescence. The proliferative effect of SDF1 was evaluated in eight fibroblast-free human pituitary adenoma cell cultures. Results: CXCR4 mRNA was expressed in 92% of growth hormone (GH)-secreting pituitary adenomas (GHoma) and 81% of nonfunctioning pituitary adenomas (NFPA), whereas SDF1 was identified in 63% and 78% of GHomas and NFPAs, respectively. Immunostaining for CXCR4 and SDF1 showed a strong homogenous labeling in all tumoral cells in both GHomas and NFPAs. In normal tissues, CXCR4 and SDF1were expressed only in a subset of anterior pituitary cells, with a lower expression of SDF1 compared with its cognate receptor. CXCR4 and SDF1 were not confined to a specific cell population in the anterior pituitary but colocalized with discrete subpopulations of GH-, prolactin-, and adrenocorticorticotropic hormone^secreting cells. Conversely, most of the SDF1-containing cells expressed CXCR4. In six of eight pituitary adenoma primary cultures, SDF1 induced a statistically significant increase in DNA synthesis that was prevented by the treatment with the CXCR4 antagonist AMD3100 or somatostatin. Conclusions: CXCR4 and SDF1 are overexpressed in human pituitary adenomas and CXCR4 activation may contribute to pituitary cell proliferation and, possibly, to adenoma development 'in humans.

Different fibronectin (FN) isoforms are generated by the alternative splicing of the primary FN transcript.We previously demonstrated that the isoform containing the extra domain B sequence of fibronectin (B-FN), a complete type-III-homology repeat, is a marker of angiogenesis that accumulates around neovasculature only during angiogenic processes. We produced a single-chain human recombinant antibody (scFv), L19, which reacts specifically with B-FN and selectively targets tumor vasculature in vivo. We used this scFv and an antibody against a pan-endothelial marker (Factor VIII) in a double-staining procedure on specimens of low-and high-grade astrocytomas to determine the percentage of B-FN-positive vessels, (denominating the resulting value angiogenic index [AI]). Compared to vascular density and proliferative activity (evaluated using antibodies to Factor VIII and Ki67, respectively), AI correlated better with tumor grade (1.6 ؎ 2.6% and 92.0 ؎ 8.7% of B-FNpositive vessels in low-and high-grade astrocytomas, respectively) and was a more precise diagnostic tool than either of the two conventional methods. In fact, discriminating analysis using these three parameters showed that only AI accurately classified 100% of the cases studied, compared to 64% and 89% correctly diagnosed by vascular density and of proliferating cells, respectively. Tumors cannot grow without a pronounced remodeling of the extracellular matrix (ECM) of the surrounding normal tissue in which the tumor grows. Remodeling of the ECM takes place through two main processes: proteolytic degradation of the normal tissue's pre-existing ECM components, and neo-synthesis of new ECM components by both neoplastic and stromal cells. The interplay between these two processes results in the generation of a neoplastic ECM whose components may differ, qualitatively and quantitatively, from their nonneoplastic counterparts. Moreover, this provisional ECM also provides a permissive environment for tumor progression of which angiogenesis is a pivotal step.

Tenascin-C exists in several polymorphic isoforms due to alternative splicing of nine fibronectin-like type III repeats. Large Tenascin-C isoforms are present in almost all normal adult tissues but are upregulated in fetal , regenerating , and neoplastic tissues. Here , we report a human antibody fragment, TN11 , derived from a phage library with high affinity for the spliced repeat C and demonstrate that this repeat is undetectable in normal adult tissues , barely detectable or undetectable in breast , lung and gastric carcinomas , meningioma , and low grade astrocytoma , but extremely abundant in high grade astrocytoma (grade III and glioblastoma) , especially around vascular structures and proliferating cells. During tumor progression, the extracellular matrix (EM) of the tissues in which a tumor grows is remodeled through proteolytic degradation and through neosynthesis of new EM components by both neoplastic cells and stromal cells. The EM generated by these processes differs from that found in normal tissues and seems to provide an environment that is more conducive for tumor progression (inductive and/or instructive), of which angiogenesis is a crucial step.