ABSTRACT
The structure-based design and progression of a screening lead to a 3nM factor VIIa/TF inhibitor with improved selectivity versus related enzymes is described.
Subject(s)
Amidines/chemistry , Amidines/pharmacology , Factor VIIa/antagonists & inhibitors , Phenylacetates/chemistry , Phenylacetates/pharmacology , Serine Proteinase Inhibitors/chemistry , Serine Proteinase Inhibitors/pharmacology , Amidines/metabolism , Binding Sites , Crystallography, X-Ray , Drug Design , Drug Evaluation, Preclinical , Factor VIIa/chemistry , Factor VIIa/metabolism , Humans , Hydrogen Bonding , Models, Molecular , Phenylacetates/metabolism , Prothrombin Time , Serine Proteinase Inhibitors/metabolism , Structure-Activity RelationshipABSTRACT
We have grown 7 bona fide non-HeLa contaminated cell lines in the cheek pouch of immunosuppressed adult hamsters. Six of the cell lines studied produced or continued to express the chorionic form of alkaline phosphatase under these conditions. The Regan isoenzyme produced in culture by the J82, T24, HCT-8, and COLO 16 cell lines disappeared in vivo with a concomitant appearance of the chorionic isoenzyme. The other cell lines, however, maintained the expression of the Regan isoenzyme when grown as a xenograft: the C41 line produced the Regan isoenzyme in culture, and continued to do so in vivo, while the BeWo cells, which synthesized the chorionic enzyme in culture were induced by in vivo growth to produce both the Regan and chorionic isoenzymes. No expression of the oncoamniotic (FL) isoenzyme was observed in any of the lines studied. Our results indicate a convergence of human tumor xenografts with respect to the production of the chorionic form of alkaline phosphatase. Furthermore, the loss of production of the Regan isoenzyme was seen in most, but not all cell lines studied. Since the oncoamniotic (FL) isoenzyme was only observed by HeLa cells growing as a xenograft, the expression of this enzyme form may be a HeLa specific phenomenon. We must now look to the regulation of the chorionic isoenzyme as the most promising avenue of approach to understanding the biological significance of altered isoenzyme expression in human tumor xenografts.
Subject(s)
Alkaline Phosphatase/biosynthesis , Isoenzymes/biosynthesis , Neoplasms/enzymology , Alkaline Phosphatase/immunology , Animals , Cell Line , Cricetinae , Homoarginine/pharmacology , Humans , Isoenzymes/immunology , Neoplasm Transplantation , Phenylalanine/pharmacology , Stereoisomerism , Transplantation, HeterologousABSTRACT
The nude mouse has been successfully employed for the propagation of human tumors, without the need for immunosuppression. In light of the limited data on embryonic gene expression in such tumors, we undertook a study of fetal isoenzyme expression during tumor growth. HeLa TCRC-1 which has been shown to produce the placental Regan isoenzyme was used in these studies. The isoenzyme produced by these cells in culture is initially replaced by an isoenzyme referred to as chorionic. In the later stages of tumor growth, the so-called oncoamniotic (FL) isoenzyme then becomes the dominant enzyme form. The chorionic isoenzyme is produced by the early chorionic membranes of the developing conceptus, while the oncoamniotic (FL) isoenzyme is most similar to that found in the fetal human intestine. The alteration in the expression of fetal isoenzymes in tumors growing in the nude mouse is similar to that seen in the immunosuppressed rat and hamster host animals, indicating that the phenomenon is not related to immunosuppression per se.
