NITRIC OXIDE AND FERRITIN MEDIATED TUMOR CELL RESISTANCE

点击翻译按钮获取中文摘要

In August 1994, I took a faculty position in the Department of Medicine at the Medical College of Wisconsin (MCW) to begin a career in academic medicine under the sponsorship of Owen W. Griilith Ph.D., Chairman and Professor of the Department of Biochemistry. I completed a fellowship at the University of Minnesota (U of M) which included 2 yrs. in the laboratory of Drs. Harry S. Jacob and Greg M. Vercellotti. The fellowship is unequivically academically oriented; I attended classes and seminars in the basic sciences, presented at scientific meetings (3 national, 3 regional), and generated 3 manuscripts (1 published, 1 accepted, 1 submitted). Because my experience in the lab has been brief, accepting the position at MCW was contingent on establishing a sponsor. Dr. Griffith has trained numerous post-doc's, and has agreed to sponsor the early phase of my career. He has facilitated the acquisition of space, equipment and technical support for my laboratory, reviewed and critiqued my proposal extensively, and has helped establish contacts with individuals that have expertise in areas in which I need further training. My laboratory adjoins Dr. Chris Chitamber, a faculty member within my division, who has published extensively in the field of iron metabolism, and with whom I interact daily. The proposal is an exciting opportunity because of the chance to develop new skills under expert guidance. The goal of the proposal is to define the role of ferritin and nitric oxide (NO) in tumor cell resistance to chemotherapy. Studies suggest that these substances may defend cells against oxidative injury. While at the U of M, we found that endothelial cells exposed to iron compounds and incubated to allow ferritin synthesis, became resistant to activated neutrophils, H202, and oxidized LDL. Tumor cells similarly treated with iron compounds became resistance to bleomycin. We examined the ability of NO to modulate ferritin synthesis and found that NO, itself, induced resistance to oxidants, particularly in hemin exposed cells. As an extension of this work, we will study whether ferritin protects tumor cells against oxidative injury from chemotherapy. With help from Dr. Jennifer Morris, transfection studies will be conducted to address the scope of ferritin protection, the effect of ferritin on iron in the injured cell, and the features of ferritin that are necessary for protection. Dr. Albert Girotti and Dr. Chitamber will assist with studies of iron kinetics and cellular injury. We will investigate whether chemotherapy induces ferritin synthesis in tumor cells. Studies have shown that actinomycin D and UV irradiation induce ferritin synthesis, and there is reason to speculate that chemotherapeutic drugs may also. Dr. Mary Claire Kennedy has published extensively in the field of iron-sulfur clusters and ferritin regulation and will provide guidance in our studies of chemotherapy induced alterations of ferritin metabolism. Drug resistant tumor cells will be studied to determine whether alterations in ferritin regulation may contribute to resistance. Finally, we will study the effects of NO production by lymphoma cells on susceptibility to chemotherapy. With the guidance of Dr. William Antholine, we will use ESR to determine if heme-oxygenase (HO) catalyzes the formation of NO-heme adducts as a protective mechanism. The proposal is an extension of work that I performed as a fellow, but includes methodology that is beyond my training. My requests for assistance with these studies have been granted with enthusiasm and I expect to develop many new skills.