The heterogeneous nature of metastatic neoplasms: implications for the treatment of cancer

Physiological Capillary Regression is not Dependent on Reducing VEGF Expression

Investigations into physiologically controlled capillary regression report the provocative finding that microvessel regression occurs in the face of persistent elevation of skeletal muscle VEGF expression. TSP-1, a negative angiogenic regulator, is increasingly being observed to temporally correlate with capillary regression, suggesting that increased TSP-1 (and not reduction in VEGF per se) is needed to initiate, and likely regulate, capillary regression. Based on evidence being gleaned from physiologically mediated regression of capillaries, it needs to be recognized that capillary regression (and perhaps capillary rarefaction with disease) is not simply the reversal of factors used to stimulate angiogenesis. Rather, the conceptual understanding that angiogenesis and capillary regression each have specific and unique requirements that are biologically constrained to opposite sides of the balance between positive and negative angioregulatory factors may shed light on why anti-VEGF therapies have not lived up to the promise in reversing angiogenesis and providing the cure that many had hoped toward fighting cancer. Emerging evidence from physiological controlled angiogenesis suggest that cases involving excessive or uncontrolled capillary expansion may be best treated by therapies designed to increase expression of negative angiogenic regulators, whereas those involving capillary rarefaction may benefit from inhibiting negative regulators (like TSP-1).

Monoclonal antibodies for characterization of the heterogeneity of normal and malignant transitional cells

We present two monoclonal antibodies (mab), Mano 4/4 and 486 P3/12, directed against tumor-associated antigens of different subpopulations of transitional cell bladder carcinoma tumors. A detailed description is given concerning their reactivity patterns in an ELISA assay against different cell lines. Using immunohistochemical staining against normal bladder mucosa, mab Mano 4/4 reacts with distinct cells in the basal layer and mab 486 P 3/12 recognizes single cells in the superficial layer. Analysing different transitional-cell carcinomas, mab Mano 4/4 reacts with 17 of 20 and mab 486 P 3/12 with 17 of 19 bladder tumors. It is emphasized that both mabs may add new information in respect to a better characterization of the heterogeneity of bladder carcinoma. A biochemical characterization of the mabs and their corresponding antigens is given. Mab Mano 4/4 is directed against a 28 kD glycoprotein and mab 486 P 3/12 is reacting with a 200 kD glycoprotein belonging to the family of CEA-like proteins.