UBC Theses and Dissertations
Two investigations in molecular pathophysiology Orban, Paul C.
This thesis is in two discrete parts. The first part deals with the mechanism of auto-stimulatory growth in the pathogenesis of malignant neoplasia. Experiments were undertaken to investigate the question of whether antagonism of growth-factor activity can lead to the death of the cells of a murine model of auto-stimulatory leukemia. Although many previous workers have examined the ability of growth-factor antagonists to inhibit the growth of the cells of human leukemias and of animal leukemia models, none have documented the complete blockage of growth, and none have documented the death of such cell populations. A model of auto-stimulatory leukemia was generated by transfecting a mouse IL-2-dependent cell line with vectors designed to cause expression of IL-2 in these cells. One series of clones was derived which grew in the absence of exogenous IL-2, and produced tumours in syngeneic mice. Cells of these clones produced very small amounts of IL-2, but their growth was not completely inhibitable by antibodies to IL-2 or the IL-2 receptor. Another clone was derived, which produced no detectable IL-2, but grew independently of exogenous IL-2. The growth of cells of this clone was completely inhibited by antibody, and death of the cells resulted. The experiments described here represent the first demonstration that antibody antagonists of the growth factor can induce the death of cells that grow by auto-stimulatory mechanisms. They support the hope that cytokine antagonists may find use as therapeutic reagents in the treatment of auto-stimulatory neoplasms. The second part of the thesis presents a new technique in gene targetting, which has broad applications in the study of gene function. Using a bacterial recombinase under the control of a tissue-specific developmentally regulated promoter, transgenic animals were derived, in which a target gene was deleted in thymocytes and their daughter cells, but no other tissues. This technique circumvents the impediment embryonic lethality may present in some gene deletion experiments, and allows questions of tissue-specifc function of genes in pathogenesis and normal development to be addressed.