Robert D. Dick

Bio: Robert D. Dick is an academic researcher from University of Michigan. The author has contributed to research in topics: Wilson's disease & Penicillamine. The author has an hindex of 21, co-authored 23 publications receiving 2573 citations. Previous affiliations of Robert D. Dick include Wayne State University & Veterans Health Administration.

Copper deficiency induced by tetrathiomolybdate suppresses tumor growth and angiogenesis.

Abstract: Copper plays an essential role in promoting angiogenesis. Tumors that become angiogenic acquire the ability to enter a phase of rapid growth and exhibit increased metastatic potential, the major cause of morbidity in cancer patients. We report that copper deficiency induced by tetrathiomolybdate (TM) significantly impairs tumor growth and angiogenesis in two animal models of breast cancer: an inflammatory breast cancer xenograft in nude mice and Her2/neu cancer-prone transgenic mice. In vitro, TM decreases the production of five proangiogenic mediators: (a) vascular endothelial growth factor; (b) fibroblast growth factor 2/basic fibroblast growth factor; (c) interleukin (IL)-1alpha; (d) IL-6; and (e) IL-8. In addition, TM inhibits vessel network formation and suppresses nuclear factor (NF)kappaB levels and transcriptional activity. Our study suggests that a major mechanism of the antiangiogenic effect of copper deficiency induced by TM is suppression of NFkappaB, contributing to a global inhibition of NFkappaB-mediated transcription of proangiogenic factors.

Treatment of Metastatic Cancer with Tetrathiomolybdate, an Anticopper, Antiangiogenic Agent: Phase I Study

Abstract: Preclinical and in vitro studies have determined that copper is an important cofactor for angiogenesis. Tetrathiomolybdate (TM) was developed as an effective anticopper therapy for the initial treatment of Wilson’s disease, an autosomal recessive disorder that leads to abnormal copper accumulation. Given the potency and uniqueness of the anticopper action of TM and its lack of toxicity, we hypothesized that TM would be a suitable agent to achieve and maintain mild copper deficiency to impair neovascularization in metastatic solid tumors. Following preclinical work that showed efficacy for this anticopper approach in mouse tumor models, we carried out a Phase I clinical trial in 18 patients with metastatic cancer who were enrolled at three dose levels of oral TM (90, 105, and 120 mg/day) administered in six divided doses with and in-between meals. Serum ceruloplasmin (Cp) was used as a surrogate marker for total body copper. Because anemia is the first clinical sign of copper deficiency, the goal of the study was to reduce Cp to 20% of baseline value without reducing hematocrit below 80% of baseline. Cp is a reliable and sensitive measure of copper status, and TM was nontoxic when Cp was reduced to 15–20% of baseline. The level III dose of TM (120 mg/day) was effective in reaching the target Cp without added toxicity. TM-induced mild copper deficiency achieved stable disease in five of six patients who were copper deficient at the target range for at least 90 days.

A novel role for XIAP in copper homeostasis through regulation of MURR1

Abstract: XIAP is a potent suppressor of apoptosis that directly inhibits specific members of the caspase family of cysteine proteases. Here we demonstrate a novel role for XIAP in the control of intracellular copper levels. XIAP was found to interact with MURR1, a factor recently implicated in copper homeostasis. XIAP binds to MURR1 in a manner that is distinct from that utilized by XIAP to bind caspases, and consistent with this, MURR1 did not affect the antiapoptotic properties of XIAP. However, cells and tissues derived from Xiap-deficient mice were found to contain reduced copper levels, while suppression of MURR1 resulted in increased intracellular copper in cultured cells. Consistent with these opposing effects, XIAP was observed to negatively regulate MURR1 protein levels by the formation of K48 polyubiquitin chains on MURR1 that promote its degradation. These findings represent the first described phenotypic alteration in Xiap-deficient mice and demonstrate that XIAP can function through MURR1 to regulate copper homeostasis.

Initial therapy of patients with Wilson's disease with tetrathiomolybdate.

Abstract: Patients with Wilson's disease who present with acute neurological symptoms often become clinically worse when initially treated with penicillamine. Other available anticopper drug therapies do not appear to offer a solution to this treatment problem. We are developing and evaluating a new drug, ammonium tetrathiomolybdate for this purpose. Theoretically, tetrathiomolybdate has optimal properties, including an immediate blockade of copper absorption and the property of forming complexes with copper in the blood, rendering the copper nontoxic. In this article, we present results from six patients treated with tetrathiomolybdate for up to 8 weeks as initial therapy. None of the five patients who had presented with acute neurological symptoms worsened. Also presented are methods of assay, preliminary stability studies, and methods of evaluating therapeutic end points with respect to copper metabolism.