Radiotherapy and antiangiogenic TM in lung cancer

Copper and Copper Complexes in Tumor Therapy

Copper (Cu), a crucial trace element in physiological processes, has garnered significant interest for its involvement in cancer progression and potential therapeutic applications. The regulation of cellular copper levels is essential for maintaining copper homeostasis, as imbalances can lead to toxicity and cell death. The development of drugs that target copper homeostasis has emerged as a promising strategy for anticancer treatment, with a particular focus on copper chelators, copper ionophores, and novel copper complexes. Recent research has also investigated the potential of copper complexes in cancer therapy.

Copper in Gynecological Diseases

Copper (Cu) is an essential micronutrient for the correct development of eukaryotic organisms. This metal plays a key role in many cellular and physiological activities, including enzymatic activity, oxygen transport, and cell signaling. Although the redox activity of Cu is crucial for enzymatic reactions, this property also makes it potentially toxic when found at high levels. Due to this dual action of Cu, highly regulated mechanisms are necessary to prevent both the deficiency and the accumulation of this metal since its dyshomeostasis may favor the development of multiple diseases, such as Menkes' and Wilson's diseases, neurodegenerative diseases, diabetes mellitus, and cancer. As the relationship between Cu and cancer has been the most studied, we analyze how this metal can affect three fundamental processes for tumor progression: cell proliferation, angiogenesis, and metastasis. Gynecological diseases are characterized by high prevalence, morbidity, and mortality, depending on the case, and mainly include benign and malignant tumors. The cellular processes that promote their progression are affected by Cu, and the mechanisms that occur may be similar. We analyze the crosstalk between Cu deregulation and gynecological diseases, focusing on therapeutic strategies derived from this metal.

The Antitumor Impact of Combining Hepatic Artery Ligation With Copper Chelators for Liver Cancer

Background

Hepatocellular carcinoma (HCC) is one of the main cancer-related mortality worldwide. Thus, there is a constant search for improvement in treatment strategies to enhance the prognosis of this malignancy. The study aims to investigate the combined antitumor activity of ammonium tetrathiomolybdate (TM, copper chelator) combined with hepatic artery ligation (HAL) for liver cancer.

Methods

A total of 40 Sprague-Dawley (SD) rats bearing hepatic tumors were randomly divided into four groups: the control group without any treatment (control), HAL only (HAL), given TM by gavage (TM), and given TM combined with HAL (HAL + TM). The concentrations of serum copper were measured at the predetermined time points. Tumor growth rate, overall survival (OS), expression of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and microvessel density (MVD), as determined by immunohistochemical examination, were compared.

Results

HAL treatment transiently could elevate alanine transaminase (ALT) and aspartate transaminase (AST) but resumed to baseline within 1 week. Serum copper was significantly increased in tumor-bearing animals over time. The values of serum copper in the three treatment groups were significantly lower than those in the control group at different time points, with the lowest values observed in the TM group (P < .05). The average tumor size was 30.33 ± 2.58, 20.83 ± 2.93, 16.80 ± 3.84, and 10.88 ± 1.08 mm in the control, HAL, TM, and HAL + TM groups, respectively (HAL + TM vs other groups, all P < .05). In addition, the expression levels of HIF-1α, VEGF, and MVD were significantly lower in the HAL + TM group than those in the other groups (P < .05). The OS of rats in the combined groups was significantly prolonged combined to the other groups (P < .05), with survival time of 19.1 ± 0.64, 25.4 ± 1.24, 25.3 ± 1.78, and 29.9 ± 2.22 days in the control, HAL, TM, and HAL + TM groups, respectively.

Conclusion

These findings suggest that combined treatment with TM and HAL holds great potential for liver cancer treatment by reducing tumor hypoxia and angiogenesis. The observed results indicate that these combinations may offer a novel target and strategy for interventional therapy of liver cancer.

Regulatory roles of copper metabolism and cuproptosis in human cancers

Copper is an essential micronutrient for human body and plays a vital role in various biological processes including cellular respiration and free radical detoxification. Generally, copper metabolism in the body is in a stable state, and there are specific mechanisms to regulate copper metabolism and maintain copper homeostasis. Dysregulation of copper metabolism may have a great connection with various types of diseases, such as Wilson disease causing copper overload and Menkes disease causing copper deficiency. Cancer presents high mortality rates in the world due to the unlimited proliferation potential, apoptosis escape and immune escape properties to induce organ failure. Copper is thought to have a great connection with cancer, such as elevated levels in cancer tissue and serum. Copper also affects tumor progression by affecting angiogenesis, metastasis and other processes. Notably, cuproptosis is a novel form of cell death that may provide novel targeting strategies for developing cancer therapy. Copper chelators and copper ionophores are two copper coordinating compounds for the treatment of cancer. This review will explore the relationship between copper metabolism and cancers, and clarify copper metabolism and cuproptosis for cancer targeted therapy.

High-Affinity Cu(I)-Chelator with Potential Anti-Tumorigenic Action-A Proof-of-Principle Experimental Study of Human H460 Tumors in the CAM Assay

Human lung cancer ranks among the most frequently treated cancers worldwide. As copper appears critical to angiogenesis and tumor growth, selective removal of copper represents a promising strategy to restrict tumor growth. To this end, we explored the activity of the novel high-affinity membrane-permeant Cu(I) chelator PSP-2 featuring a low-zeptomolar dissociation constant. Using H460 human lung cancer cells, we generated small tumors on the chorioallantoic membrane of the chicken embryo (CAM assay) and studied the effects of topical PSP-2 application on their weight and vessel density after one week. We observed a significant angiosuppression along with a marked decrease in tumor weight under PSP-2 application compared to controls. Moreover, PSP-2 exposure resulted in lower ki67⁺ cell numbers at a low dose but increased cell count under a high dose. Moreover, HIF-1α⁺ cells were significantly reduced with low-dose PSP-2 exposure compared to high-dose and control. The total copper content was considerably lower in PSP-2 treated tumors, although statistically not significant. Altogether, PSP-2 shows promising potential as an anti-cancer drug. Nevertheless, further animal experiments and application to different tumor types are mandatory to support these initial findings, paving the way toward clinical trials.

The molecular and cellular basis of copper dysregulation and its relationship with human pathologies

Copper (Cu) is an essential micronutrient required for the activity of redox-active enzymes involved in critical metabolic reactions, signaling pathways, and biological functions. Transporters and chaperones control Cu ion levels and bioavailability to ensure proper subcellular and systemic Cu distribution. Intensive research has focused on understanding how mammalian cells maintain Cu homeostasis, and how molecular signals coordinate Cu acquisition and storage within organs. In humans, mutations of genes that regulate Cu homeostasis or facilitate interactions with Cu ions lead to numerous pathologic conditions. Malfunctions of the Cu⁺ -transporting ATPases ATP7A and ATP7B cause Menkes disease and Wilson disease, respectively. Additionally, defects in the mitochondrial and cellular distributions and homeostasis of Cu lead to severe neurodegenerative conditions, mitochondrial myopathies, and metabolic diseases. Cu has a dual nature in carcinogenesis as a promotor of tumor growth and an inducer of redox stress in cancer cells. Cu also plays role in cancer treatment as a component of drugs and a regulator of drug sensitivity and uptake. In this review, we provide an overview of the current knowledge of Cu metabolism and transport and its relation to various human pathologies.

A dicyanomethylene-4H-pyran-based fluorescence probe with high selectivity and sensitivity for detecting copper (II) and its bioimaging in living cells and tissue

Copper (Cu) plays a significant role in the process of oxygenic photosynthesis in living systems. The detection of copper ion (Cu²⁺) is valuable and meaningful for further investigating the functions of Cu²⁺ under physiological and pathological conditions. In this paper, a novel fluorescence probe DCM-Cu based on the near-infrared (NIR) fluorophore dicyanomethylene-4H-pyran (DCM) was designed for Cu²⁺ detection. The probe DCM-Cu possessed characteristic of "turn-on" fluorescent signal in the presence of Cu²⁺ through the enhanced ICT process. It exhibited satisfactory sensitivity and selectivity toward Cu²⁺. A good linear correlation was observed between the concentrations of Cu²⁺ and the fluorescence intensities at 700 nm. The detection limit (LOD) of DCM-Cu toward Cu²⁺ was calculated to be 2.54 × 10^-8 M. Importantly, DCM-Cu was successfully applied in the detection of Cu²⁺ in living MCF-7 cells and tumor tissue with low cytotoxicity. Therefore, this probe would have the potential to monitor cellular Cu²⁺ in the living system and be applied to the diagnosis of related diseases.

Copper homeostasis: Emerging target for cancer treatment

Copper (Cu) is an essential micronutrient involved in a variety of fundamental biological processes. Recently, disorder of Cu homeostasis can be observed in many malignancies. Elevated Cu levels in serum and tissue are correlated with cancer progression. Hence, targeting Cu has emerged as a novel strategy in cancer treatment. This review provides an overview of physiological Cu metabolism and its homeostasis, followed by a discussion of the dysregulation of Cu homeostasis in cancer and the effects of Cu on cancer progression. Finally, recent therapeutic advances using Cu coordination complexes as anticancer agents, as well as the mechanisms of their anti-cancer action are discussed. This review contributes full comprehension to the role of Cu in cancer and demonstrates the broad application prospect of Cu coordination compounds as potential therapeutic agents.

Redox cycling of copper by coumarin-di(2-picolyl)amine hybrid molecule leads to ROS-mediated modulation of redox scavengers, DNA damage and cell death in diethylnitrosamine induced hepatocellular carcinoma

Targeted therapy is a new strategy for cancer treatment that targets chemical entities specific to cancer cells than normal ones. One of the features associated with malignancy is the elevated copper which plays an integral role in angiogenesis. Work is in progress in our lab to identify new copper chelators to target elevated copper under targeted therapy for the killing of cancer cells. Recently, a coumarin-based copper chelator, di(2-picolyl)amine-3(bromoacetyl)coumarin hybrid molecule (ligand-L) has been synthesized by us, and also studied its copper-dependent macromolecular damage response in copper overloaded lymphocytes. The present study investigates the anticancer activity of ligand-L and its mode of action in rat model of diethylnitrosamine (DEN) induced hepatocellular carcinoma. It has been found that liver tissue has a marked increase in copper levels in DEN induced hepatocellular carcinoma. Ex vivo results showed that ligand-L inhibited cell viability, induced reactive oxygen species (ROS) generation, DNA damage, loss of mitochondrial membrane potential and caspase-3 activation in isolated hepatocellular carcinoma cells (HCC). All these effects induced by ligand-L were abrogated by neocuproine and N-acetylcysteine (ROS scavenger). Further, ligand-L treatment of animals bearing hepatocellular carcinoma results in an increment in the cellular redox scavengers, lipid peroxidation and DNA breakage in malignant hepatocytes. In vivo studies using ligand-L also showed that ligand-L possesses anticancer properties as evidenced by improvement in liver marker enzymes and liver surface morphology, and reduced alpha-fetoprotein in the treated group compared to untreated cancer-induced group. Overall, this study suggests that copper-ligand-L interaction leads to ROS generation which caused DNA damage and apoptosis in malignant cells. This study provides enough support to establish ligand-L as a clinically relevant lead molecule for the treatment of different malignancies.

Current Biomedical Use of Copper Chelation Therapy

Copper is an essential microelement that plays an important role in a wide variety of biological processes. Copper concentration has to be finely regulated, as any imbalance in its homeostasis can induce abnormalities. In particular, excess copper plays an important role in the etiopathogenesis of the genetic disease Wilson's syndrome, in neurological and neurodegenerative pathologies such as Alzheimer's and Parkinson's diseases, in idiopathic pulmonary fibrosis, in diabetes, and in several forms of cancer. Copper chelating agents are among the most promising tools to keep copper concentration at physiological levels. In this review, we focus on the most relevant compounds experimentally and clinically evaluated for their ability to counteract copper homeostasis deregulation. In particular, we provide a general overview of the main disorders characterized by a pathological increase in copper levels, summarizing the principal copper chelating therapies adopted in clinical trials.

Anti-cancer activities of metal-based complexes by regulating the VEGF/VEGFR2 signaling pathway and apoptosis-related factors Bcl-2, Bax, and caspase-9 to inhibit angiogenesis and induce apoptosis

Copper-based complexes exhibited multiple anti-cancer functions by regulating the expressions of Bcl-2, Bax, and caspase-9 and activating the VEGF/VEGFR2 signaling pathway.

Antineoplastic Effect of a Combined Mitotane Treatment/Ionizing Radiation in Adrenocortical Carcinoma: A Preclinical Study

Mitotane (MTT) is an adrenolytic drug used in adjuvant and advanced treatments of adrenocortical carcinoma (ACC). Ionizing radiation (IR) is also used in adrenal cancer treatment, even though its biological action remains unknown. To provide a reliable in vivo preclinical model of ACC, we used mouse xenografts bearing human ACC to test the effects of MTT and IR alone and in combination. We evaluated tumor growth inhibition by the RECIST criteria and analyzed the cell cycle by flow cytometry (FCM). In the xenograft ACC model treated with MTT/IR in combination, we observed a marked inhibition of tumor growth, with strong tumor regression (p < 0.0001) compared to MTT and IR given alone (p < 0.05). The MTT results confirm its antisteroidogenic activity (p < 0.05) in the xenograft ACC model, revealing its ability to render cancer cells more prone to radiotherapy treatment. In addition, to explain the biological effect of these treatments on the Mismatch Repair System (MMR), we interfered with the MSH2 gene expression in untreated and MTT/IR-treated H295R and SW13 cell lines. Moreover, we observed that upon treatment with MTT/IR to induce DNA damage, MSH2 gene inhibition in both the H295R and SW13 cell lines did not allow DNA damage repair, thus inducing cell death. In conclusion, MTT seems to have a radiosensitizing property and, when given in combination with IR, is able to promote neoplastic growth inhibition, leading to a significant reduction in tumor size due to cell death.

Systematic analysis of concentrations of 52 elements in tumor and counterpart normal tissues of patients with non-small cell lung cancer

BACKGROUND

Many studies have documented the abnormal concentrations of major/trace elements in serum or malignant tissues of patients, but very few works systematically tested the concentrations of elements in tumor tissues in comparison with paired adjacent normal tissues from the same patients.

METHODS

Tumor and adjacent normal lung tissues were obtained from 93 patients with previously untreated NSCLC, and 43 patients whose tumor and paired normal lung tissues reached 200 mg or more were selected for measurement of the elements' concentrations using an inductively coupled plasma-atomic emission spectrometer.

RESULTS

We found that the concentrations of the 52 elements varied from 0.4 ng/g tissue (Lu, Pd, and Tm) to 1 658 000 ng/g (Na), 1 951 000 ng/g (P), and 2 495 000 ng/g (K). Thirty eight of the 52 (73.1%) elements showed approximately equal concentrations in tumor and adjacent normal lung tissues of the patients. The concentrations of nine elements (K, P, Mg, Zn, Rb, Cu, Se, Cs, and Tl) in tumor samples were significantly higher than their paired normal lung tissues, and five elements (Na, Fe, Cr, Cd, and Ge) exhibited decreased concentrations in cancer samples compared to counterpart normal lung tissues. Low Fe in tumor samples was associated with smoking history, whereas low Cr was associated with histology (squamous cell carcinoma) of the patients.

CONCLUSIONS

Our results demonstrate that measurement of elements' concentrations in both cancer and paired normal tissues is important to get insights into the roles of these elements in carcinogenesis, and therapeutic approaches to normalize the elements are warranted to treat NSCLCs.

Synthesis, characterization, and anticancer activity of two mixed ligand copper(ii) complexes by regulating the VEGF/VEGFR2 signaling pathway

Two mixed-ligand copper-based complexes significantly exhibit anti-cervical cancer activity by regulating the important signalling molecules downstream of the VEGF/VEGFR2 signalling pathway.

Tetrathiomolybdate Therapy Protects Against Concanavalin a and Carbon Tetrachloride Hepatic Damage in Mice

Tetrathiomolybdate, an anticopper drug, has been shown to protect mice against pulmonary fibrosis from bleomycin. Our hypothesis is that it does so by inhibiting fibrosis-inducing cytokines. Indeed, we have good evidence, not yet published, that tetrathiomolybdate inhibits pulmonary levels of transforming growth factor–β and tumor necrosis factor-α expression in these bleomycin experiments. Herein, we evaluate tetrathiomolybdate's effectiveness in mitigating hepatitis and fibrosis in mice from the hepatotoxins, concanavalin A and carbon tetrachloride, and its inhibition of cytokines as a possible mechanism. In short-term experiments, concanavalin A elevated serum amino leucine transferase levels several fold, and tetrathiomolybdate completely prevented this increase. In additional experiments, tetrathiomolybdate therapy reversed the elevated serum transaminase levels despite continued concanavalin A injections, with nearly significant serum interleukin-1β inhibition. Concanavalin A given for 12 weeks produced mild fibrosis, whereas concomitant tetrathiomolybdate treatment resulted in normal histology. Carbon tetrachloride given for 12 weeks resulted in very high serum amino leucine transferase levels, high serum transforming growth factor–β levels, cirrhosis as seen histologically, and increase in liver hydroxyproline, a measure of fibrosis. Concomitant tetrathiomolybdate partially and significantly protected against increases in amino leucine transferase and transforming growth factor–β, fully protected against the increase in hydroxyproline, and resulted in normal histology. In conclusion, tetrathiomolybdate protects against the hepatitis and fibrosis produced by these hepatotoxins, probably by inhibiting the excessive increase in inflammatory and fibrotic cytokines.

Copper suppression as cancer therapy: the rationale for copper chelating agents in BRAFV600 mutated melanoma

The successful targeting of oncogenic BRAF^V600 represents one of the landmark breakthroughs in therapy for advanced melanoma. While the initial clinical benefit can be dramatic, resistance is common due to a number of mechanisms, including MAPK pathway reactivation. Recent data have revealed a novel role for copper (Cu) in BRAF signaling with potential clinical implications. The history, preclinical data and efficacy of Cu chelating agents in cancer, specifically tetrathiomolybdate, will be reviewed with a focus on the rationale for targeting the MAPK cascade in melanoma through novel combination strategies.

Tetrathiomolybdate mediates cisplatin-induced p38 signaling and EGFR degradation and enhances response to cisplatin therapy in gynecologic cancers

Cisplatin and its analogs are among the most widely used chemotherapeutic agents against various types of cancer. It is known that cisplatin can activate epidermal growth factor receptor (EGFR), which may provide a survival benefit in cancers. Tetrathiomolybdate (TM) is a potent anti-cancer and anti-angiogenic agent and has been investigated in a number of clinical trials for cancer. In this study, we explore the therapeutic potential of TM on cisplatin-mediated EGFR regulation. Our study shows that TM is not cytotoxic, but exerts an anti-proliferative effect in ECC-1 cells. However, TM treatment prior to cisplatin markedly improves cisplatin-induced cytotoxicity. TM suppressed cisplatin-induced activation of EGFR while potentiating activation of p38; the activation of p38 signaling appeared to promote cisplatin-induced EGFR degradation. These results are in contrast to what we saw when cells were co-treated with cisplatin plus an EGFR tyrosine kinase inhibitor, where receptor activation was inhibited but receptor degradation was also blocked. Our current study is in agreement with previous findings that TM may have a therapeutic benefit by inhibiting EGFR activation. We furthermore provide evidence that TM may provide an additional benefit by potentiating p38 activation following cisplatin treatment, which may in turn promote receptor degradation by cisplatin.

Targeting copper in cancer therapy: 'Copper That Cancer'

Copper is an essential micronutrient involved in fundamental life processes that are conserved throughout all forms of life. The ability of copper to catalyze oxidation-reduction (redox) reactions, which can inadvertently lead to the production of reactive oxygen species (ROS), necessitates the tight homeostatic regulation of copper within the body. Many cancer types exhibit increased intratumoral copper and/or altered systemic copper distribution. The realization that copper serves as a limiting factor for multiple aspects of tumor progression, including growth, angiogenesis and metastasis, has prompted the development of copper-specific chelators as therapies to inhibit these processes. Another therapeutic approach utilizes specific ionophores that deliver copper to cells to increase intracellular copper levels. The therapeutic window between normal and cancerous cells when intracellular copper is forcibly increased, is the premise for the development of copper-ionophores endowed with anticancer properties. Also under investigation is the use of copper to replace platinum in coordination complexes currently used as mainstream chemotherapies. In comparison to platinum-based drugs, these promising copper coordination complexes may be more potent anticancer agents, with reduced toxicity toward normal cells and they may potentially circumvent the chemoresistance associated with recurrent platinum treatment. In addition, cancerous cells can adapt their copper homeostatic mechanisms to acquire resistance to conventional platinum-based drugs and certain copper coordination complexes can re-sensitize cancer cells to these drugs. This review will outline the biological importance of copper and copper homeostasis in mammalian cells, followed by a discussion of our current understanding of copper dysregulation in cancer, and the recent therapeutic advances using copper coordination complexes as anticancer agents.

Role of copper in regression of cardiac hypertrophy

Pressure overload causes an accumulation of homocysteine in the heart, which is accompanied by copper depletion through the formation of copper-homocysteine complexes and the excretion of the complexes. Copper supplementation recovers cytochrome c oxidase (CCO) activity and promotes myocardial angiogenesis, along with the regression of cardiac hypertrophy and the recovery of cardiac contractile function. Increased copper availability is responsible for the recovery of CCO activity. Copper promoted expression of angiogenesis factors including vascular endothelial growth factor (VEGF) in endothelial cells is responsible for angiogenesis. VEGF receptor-2 (VEGFR-2) is critical for hypertrophic growth of cardiomyocytes and VEGFR-1 is essential for the regression of cardiomyocyte hypertrophy. Copper, through promoting VEGF production and suppressing VEGFR-2, switches the VEGF signaling pathway from VEGFR-2-dependent to VEGFR-1-dependent, leading to the regression of cardiomyocyte hypertrophy. Copper is also required for hypoxia-inducible factor-1 (HIF-1) transcriptional activity, acting on the interaction between HIF-1 and the hypoxia responsible element and the formation of HIF-1 transcriptional complex by inhibiting the factor inhibiting HIF-1. Therefore, therapeutic targets for copper supplementation-induced regression of cardiac hypertrophy include: (1) the recovery of copper availability for CCO and other critical cellular events; (2) the activation of HIF-1 transcriptional complex leading to the promotion of angiogenesis in the endothelial cells by VEGF and other factors; (3) the activation of VEGFR-1-dependent regression signaling pathway in the cardiomyocytes; and (4) the inhibition of VEGFR-2 through post-translational regulation in the hypertrophic cardiomyocytes. Future studies should focus on target-specific delivery of copper for the development of clinical application.

The promise of copper lowering therapy with tetrathiomolybdate in the cure of cancer and in the treatment of inflammatory disease

Tetrathiomolybdate (TM) is a unique anticopper drug developed for the treatment of the neurologic presentation of Wilson's disease, for which it is excellent. Since it was known copper was required for angiogenesis, TM was tested on mouse cancer models to see if it would inhibit tumor growth based on an antiangiogenic effect. TM was extremely effective in these models, but all the tumors in the models started small in size - micrometastatic in size. Later, TM was tested in numerous human cancer trials, where it showed only modest effects. However, the mouse lesson of efficacy against micro disease was forgotten - all the trials were against bulky, advanced cancer. Now, the mouse evidence is coming back to life. Three groups are curing, or having major efficacy of TM, against advanced human cancers, heretofore virtually incurable, particularly if the cancer has been reduced to no evidence of disease (NED) status by conventional therapy. In that situation, where the remaining disease is micrometastatic, TM therapy appears to be curative. We have designed and initiated a study of TM in canine osteosarcoma at the micrometastatic phase to help put these findings on a firm scientific basis. TM also has major anti-inflammatory properties by inhibiting copper dependent cytokines involved in inflammation. This anti-inflammatory effect may be involved in TM's anticancer effect because cancers, as they advance, attract inflammatory cells that provide a plethora of additional proangiogenic agents.

Using canine osteosarcoma as a model to assess efficacy of novel therapies: can old dogs teach us new tricks?

Since its domestication more than 10,000 years ago, the dog has been the animal that most intimately shares our work and homelife. Interestingly, the dog also shares many of our diseases including cancer such as osteosarcoma. Like the human, osteosarcoma is the most common bone malignancy of the dog and death from pulmonary metastasis is the most common outcome. The incidence of this spontaneous bone neoplasm occurs ten times more frequently that it does so in children with about 8,000-10,000 cases estimated to occur in dogs in the USA. Because there is no "standard of care" in veterinary medicine, the dog can also serve us by being a model for this disease in children. Although the most common therapy for the dog with osteosarcoma is amputation followed by chemotherapy, not all owners choose this route. Consequently, novel therapeutic interventions can be attempted in the dog with or without chemotherapy that could not be done in humans with osteosarcoma due to ethical concerns. This chapter will focus on the novel therapies in the dog that have been reported or are in veterinary clinical trials at the author's institution. It is hoped that collaboration between veterinary oncologists and pediatric oncologists will lead to the development of novel therapies for (micro- or macro-) metastatic osteosarcoma that improve survival and might ultimately lead to a cure in both species.

Toward a molecular understanding of the photosensitizer-copper interaction for tumor destruction

The aim of this study was to shown that the photosensitizer in photodynamic therapy (PDT) can contribute to the dark toxicity and phototoxicity of the tumor by binding with copper. This binding process can remove the copper from the body, stopping angiogenesis as well as activating the mechanisms of cell death, such as apoptosis and necrosis. In PDT, this coupling may be considered a new route for fighting cancer in addition to those already known which involve reactive oxygen species.

A role for the copper transporter Ctr1 in the synergistic interaction between hyperthermia and cisplatin treatment

PURPOSE

Hyperthermia enhances cytotoxic effects of chemotherapeutic agents such as cisplatin. However, the underlying molecular mechanisms remain unclear. We hypothesised that hyperthermia increases cisplatin accumulation and efficacy by modulating function of copper transport protein 1 (Ctr1), a major regulator of cellular cisplatin uptake. We examined the significance of Ctr1 in the synergistic interaction between hyperthermia and cisplatin. We assessed the importance of cisplatin- and hyperthermia-induced Ctr1 multimerisation in sensitising cells to cisplatin cytotoxicity.

MATERIALS AND METHODS

Ctr1 protein levels and cisplatin sensitivities were assessed in bladder cancer cell lines with immunoblotting and clonogenic survival assays. Using Myc-tagged-Ctr1 HEK293 cells, we assessed the effect of hyperthermia on Ctr1 multimerisation with immunoblotting. The effect of hyperthermia on cisplatin sensitivity and accumulation was assessed in wild-type (WT) and Ctr1 knockout (Ctr1-/-) mouse embryonic fibroblasts (MEFs) with clonogenic assays and inductively coupled plasma-mass spectrometry (ICP-MS).

RESULTS

Increased Ctr1 protein expression was observed for the most cisplatin-sensitive bladder cancer cell lines and MEFs. Heat-induced increase in Ctr1 multimerisation with cisplatin was observed in Myc-tagged Ctr1 cells. Hyperthermia enhanced cisplatin-mediated cytotoxicity in WT more than Ctr1-/- cells (dose modifying factors 1.75 versus 1.4, respectively). WT cells accumulated more platinum versus Ctr1-/- cells; this was further increased by hyperthermia in WT cells.

CONCLUSIONS

Hyperthermia enhanced cisplatin uptake and cytotoxicity in WT cells. Heat increased Ctr1 activity by increasing multimerisation, enhancing drug cytotoxicity. Furthermore, Ctr1 protein profiles of bladder tumours, as well as other tumour types, may predict their response to cisplatin and overall efficacy of treatment.

Atorvastatin inhibits RhoC function and limits head and neck cancer metastasis

OBJECTIVE

RhoC oncogene is a well characterized marker of metastasis in a majority of invasive cancers, including HNSCC. Elevated RhoC expression has been found to be associated with distant metastasis. Statins are a class of drugs that are used to reduce cholesterol levels by inhibiting HMG-CoA reductase activity which in turns prevents mevalonate synthesis, which is a precursor for synthesis of cholesterol and prenylation. Interestingly, the proper function of Rho proteins depends on prenylation. Significantly, it has been reported that metastasis in human melanoma can be reduced by atorvastatin which inhibits RhoC activity by preventing its geranylgeranylation. Given that RhoC is a key oncogene involved in metastasis, we hypothesized Atorvastatin can reduce head and neck metastasis by inhibiting RhoC activity.

METHODS

In vitro and in vivo studies were carried out to evaluate the ability of Atorvastatin to inhibit RhoC function and HNSCC metastasis. Cell motility, proliferation, cell invasion, and colony formation assays were performed according to the standard protocols.

RESULTS

Atorvastatin treatment significantly reduced the active form of RhoC in vitro and diminished cell motility, invasion, proliferation and colony formation. Importantly, we observed a significant decrease in p-ERK1/2 and p-STAT3 in Atorvastatin treated cell lines. In vivo experiments revealed inhibition of angiogenesis and lung metastases with Atorvastatin therapy.

CONCLUSIONS

This study is the first of its kind to establish a potential role of Atorvastatin in head and neck cancer therapy. These findings suggest that Atorvastatin can be a potential low risk adjuvant therapy to minimize metastases in aggressive forms of HNSCC.

Copper dependence of angioproliferation in pulmonary arterial hypertension in rats and humans

Obliteration of the vascular lumen by endothelial cell growth is a hallmark of many forms of severe pulmonary arterial hypertension. Copper plays a significant role in the control of endothelial cell proliferation in cancer and wound-healing. We sought to determine whether angioproliferation in rats with experimental pulmonary arterial hypertension and pulmonary microvascular endothelial cell proliferation in humans depend on the proangiogenic action of copper. A copper-depleted diet prevented, and copper chelation with tetrathiomolybdate reversed, the development of severe experimental pulmonary arterial hypertension. The copper chelation-induced reopening of obliterated vessels was caused by caspase-independent apoptosis, reduced vessel wall cell proliferation, and a normalization of vessel wall structure. No evidence was found for a role of super oxide-1 inhibition or lysyl-oxidase-1 inhibition in the reversal of angioproliferation. Tetrathiomolybdate inhibited the proliferation of human pulmonary microvascular endothelial cells, isolated from explanted lungs from control subjects and patients with pulmonary arterial hypertension. These data suggest that the inhibition of endothelial cell proliferation by a copper-restricting strategy could be explored as a new therapeutic approach in pulmonary arterial hypertension. It remains to be determined, however, whether potential toxicity to the right ventricle is offset by the beneficial pulmonary vascular effects of antiangiogenic treatment in patients with pulmonary arterial hypertension.

Tetrathiomolybdate induces doxorubicin sensitivity in resistant tumor cell lines

OBJECTIVE

Doxorubicin is a potent anti-cancer agent with efficacy against a broad range of tumors, including endometrial cancer. Doxorubicin produces reactive oxygen species (ROS) resulting in cytotoxicity. Tetrathiomolybdate (TM), a copper-chelating agent, is known to target a cellular antioxidant enzyme copper/zinc-superoxide dismutase. This study tests the hypothesis that TM can modulate antioxidants in tumor cells and render doxorubicin resistant tumor cells sensitive to doxorubicin.

METHODS

The anti-cancer activities of doxorubicin and TM, as single agents and in combination, were assessed. Flow cytometric and immunoblot analysis were conducted to investigate the induction of apoptosis and changes in apoptotic signaling pathways.

RESULTS

Doxorubicin-induced growth inhibition was observed in each endometrial cancer cell line (ECC-1, AN3CA, and KLE) tested with cell specificity. ECC-1 and KLE cells were found to have increased resistance to doxorubicin than AN3CA cells. Moreover, doxorubicin mediated apoptosis was greater in the AN3CA cell line than ECC-1 and KLE. The combination of doxorubicin with a sub-cytotoxic level of TM was significantly more effective at inducing apoptosis in doxorubicin resistant cell lines.

CONCLUSION

Our results highlight the therapeutic potential of TM to sensitize tumor cells to doxorubicin for endometrial cancer treatment.

Zinc and tetrathiomolybdate for the treatment of Wilson's disease and the potential efficacy of anticopper therapy in a wide variety of diseases

Wilson's disease, an autosomal recessive disease of copper accumulation and copper toxicity primarily in the liver and brain, has been the engine that has driven the development of anticopper drugs. Here we first briefly review Wilson's disease, then review the four anticopper drugs used to treat Wilson's disease. We then discuss the results of therapy with anticopper drugs in Wilson's disease, with special emphasis on the newer and better drugs, zinc and tetrathiomolybdate. We then discuss new areas of anticopper therapy, lowering copper availability with tetrathiomolybdate as a therapy in fibrotic, inflammatory, and autoimmune disorders. Many of the cytokines which promote these disorders are copper dependent, and lowering copper availability lessens the activity of these cytokines, favorably influencing a variety of disease processes. Copper in the blood can be thought of as in two pools. One pool is covalently bound in ceruloplasmin, a protein containing six coppers, synthesized by the liver and secreted into the blood. Ceruloplasmin copper accounts for almost 85 to 90% of the blood copper in normal people. This copper is tightly bound and not readily available for cellular uptake and copper toxicity. The other 10-15% of copper is more loosely bound to albumin and other small molecules in the blood, and is readily and freely available to cells and available to cause copper toxicity, if this pool of copper is increased. We call this latter pool of copper "free" copper because of its more ready availability. However, it should be understood that it is not completely free, always being bound to albumin and other molecules. It is this pool of free copper that is greatly expanded in untreated Wilson's patients undergoing copper toxicity.

Copper chelator ATN-224 inhibits endothelial function by multiple mechanisms

Copper is required for the proliferation of endothelial cells and copper-lowering therapy reduces tumour growth in animal models. It has been reported that ATN-224, a novel copper chelator, potently inhibits the activity of the copper-dependent enzyme superoxide dismutase 1 (SOD1) in endothelial cells. We performed microarray analysis of gene expression in endothelial cells exposed to ATN-224 which revealed upregulation of stress response genes including heme-oxygenase 1 (HO-1) and differential regulation of several genes previously implicated in angiogenesis including CXCR4, ANGP2, PGES2, RHAMM, ITB4 and AQP1 (p<0.01). These changes were confirmed on qPCR. Treatment of HUVEC with ATN-224 caused increased superoxide levels, phospho-ERK signalling, nuclear NRF1 expression, HO-1 expression and induction of the anti-apoptotic proteins P21, BCL2 and BCLXL. There was also nuclear translocation of SOD1. SOD1 RNA interference replicated the effects of ATN-224 on endothelial cell function but did not cause upregulation of HO-1 or PGES2, suggesting additional mechanisms of action of ATN-224. Downregulation of AQP1, which has been shown to have a role in angiogenesis, was seen with both ATN-224 and SOD1 siRNA. AQP1 expression could be rescued after ATN-224 by added copper. RNA interference to AQP1 inhibited endothelial proliferation and migration, confirming the role of AQP1 in endothelial cell function. Therefore regulation of AQP1 may represent an important action of copper chelation therapy.

Phase I study of copper-binding agent ATN-224 in patients with advanced solid tumors

PURPOSE

Copper chelation reduces the secretion of many angiogenic factors and reduces tumor growth and microvascular density in animal models. ATN-224 is a second-generation analogue of ammonium tetrathiomolybdate. The aim of our phase I study was to reduce serum copper levels, as measured by ceruloplasmin, to 5 to 15 mg/dL (normal 16-60) in 14 to 21 days, to determine the pharmacokinetic profile of ATN-224 and to evaluate dose-limiting toxicities.

PATIENTS AND METHODS

Cohorts of patients were treated with escalating oral doses of ATN-224 until copper depletion followed by a titrated maintenance dose.

RESULTS

Eighteen patients received 78 cycles of ATN-224. Mean baseline ceruloplasmin was 39.6 mg/dL. The maximum administered dose was 330 mg/d where grade 3 fatigue was dose-limiting. At the maximum tolerated dose of 300 mg/d, the median time to achieve target ceruloplasmin was 21 days, and toxicities included grade 3 anemia, grade 3 neutropenia, fatigue, and sulfur eructation. ATN-224 treatment caused a significant reduction (> 90%) in RBC superoxide dismutase 1 activity and circulating endothelial cells. Pharmacokinetic data indicate greater absorption of ATN-224 and more rapid ceruloplasmin reduction when administered with a proton pump inhibitor. Stable disease of > 6 months was observed in 2 patients.

CONCLUSIONS

Oral ATN-224 is a well-tolerated therapy and at a loading dose of 300 mg/d leads to a reduction of serum ceruloplasmin levels in 80% patients within 21 days. A loading dose of 300 mg/d for 2 weeks followed by a titrated maintenance dose will be the recommended starting dose for phase II study.

In vivo efficacy of marimastat and chemoradiation in head and neck cancer xenografts

OBJECTIVE

To assess the effect of combining a synthetic matrix metalloprotease inhibitor and chemoradiation therapy on tumor growth in a murine model of head and neck squamous-cell carcinoma (SCC).

METHODS

Athymic, nude mice bearing SCC-1 xenografts were used to comprise 4 treatment groups: (1) control receiving vehicle alone, (2) marimastat alone, (3) cisplatin + radiation in combination and (4) marimastat + cisplatin + radiation in combination. The marimastat was administered at a dose of 8.7 mg/kg/day over a 14-day period via a subcutaneous osmotic pump. The control group received vehicle only via a subcutaneous osmotic pump. Radiotherapy was given in 4 fractions of 8 Gy divided over days 8, 12, 16 and 20 with 4 intraperitoneal doses of cisplatin (3 mg/kg) 1 h before each fraction of radiation.

RESULTS

Animals receiving triple treatment had delayed growth, measured as lengthened tumor doubling time, compared to the cisplatin + radiation combination (p = 0.03). Also, compared to control, the triple-treatment group (p = 0.005) had delayed growth in terms of doubling time. Factor VIII immunohistochemistry to assess microvessel density did not demonstrate a reduction in neovascularization between the triple-treatment and cisplatin + radiation combination groups. Statistical analysis failed to demonstrate any significant difference among groups.

CONCLUSIONS

Chemoradiation + marimastat therapy had delayed tumor growth, compared to the chemoradiation alone. Based on these results, marimastat may work in combination with chemotherapy and radiation to inhibit tumor growth.

Tetrathiomolybdate Is Partially Protective Against Hyperglycemia in Rodent Models of Diabetes

The objective was to evaluate whether copper lowering therapy with tetrathiomolybdate (TM) affected blood sugar levels in three rodent models of diabetes, streptozotocin (STZ) treated rats and mice, and the db/db mouse model. STZ was administered to rats and mice, and blood sugar levels were followed over a protracted time in these and non-STZ control animals. TM was administered by oral gavage (rats) or in the drinking water (mice) to a portion of the rats and mice to observe effects on blood sugar. Mice with genetically determined diabetes (db/db) were studied by giving half the mice TM in the drinking water and following blood sugar. The results show that TM caused a significant reduction in blood glucose in both STZ treated rats and mice, but no effect on blood glucose in db/db mice. However, TM caused a significant reduction in proteinuria in db/db animals. The results are discussed around the likelihood that TM is inhibiting ongoing inflammatory damage in the pancreas from STZ. A metabolic effect of TM on blood glucose is possible but seems less likely. TM is also likely inhibiting inflammatory and/or fibrogenic effects in the kidneys of db/db mice.

Copper and angiogenesis: unravelling a relationship key to cancer progression

1. Angiogenesis, the formation of new capillaries from existing vasculature, is a critical process in normal physiology as well as several physiopathologies. A desire to curb the supportive role angiogenesis plays in the development and metastasis of cancers has driven exploration into anti-angiogenic strategies as cancer therapeutics. Key to this, angiogenesis additionally displays an exquisite sensitivity to bioavailable copper. Depletion of copper has been shown to inhibit angiogenesis in a wide variety of cancer cell and xenograft systems. Several clinical trials using copper chelation as either an adjuvant or primary therapy have been conducted. Yet, the biological basis for the sensitivity of angiogenesis remains unclear. Numerous molecules important to angiogenesis regulation have been shown to be either directly or indirectly influenced by copper, yet a clear probative answer to the connection remains elusive. 2. Measurements of copper in biological systems have historically relied on techniques that, although demonstrably powerful, provide little or no information as to the spatial distribution of metals in a cellular context. Therefore, several new approaches have been developed to image copper in a biological context. One such approach relies on synchrotron-derived X-rays from third-generation synchrotrons and the technique of high resolution X-ray fluorescence microprobe (XFM) analysis. 3. Recent applications of XFM approaches to the role of copper in regulating angiogenesis have provided unique insight into the connection between copper and cellular behaviour. Using XFM, copper has been shown to be highly spatially regulated, as it is translocated from perinuclear areas of the cell towards the tips of extending filopodia and across the cell membrane into the extracellular space during angiogenic processes. Such findings may explain the heightened sensitivity of this cellular process to this transition metal and set a new paradigm for the kinds of regulatory roles that the spatial dynamics of cellular transition metals may play.

Clioquinol promotes cancer cell toxicity through tumor necrosis factor alpha release from macrophages

Copper has an important role in cancer growth, angiogenesis, and metastasis. Previous studies have shown that cell-permeable metal ligands, including clioquinol (CQ) and pyrrolidine dithiocarbamate, inhibit cancer cell growth in cell culture and in vivo. The mechanism of action has not been fully determined but may involve metal-mediated inhibition of cancer cell proteasome activity. However, these studies do not fully account for the ability of cell-permeable metal ligands to inhibit cancer cell growth without affecting normal cells. In this study, we examined the effect of CQ on macrophage-mediated inhibition of HeLa cancer cell growth in vitro. When CQ was added to RAW 264.7 macrophage-HeLa cell cocultures, a substantial increase in HeLa cell toxicity was observed compared with CQ treatment of HeLa cells cultured alone. Transfer of conditioned medium from CQ-treated macrophages to HeLa cells also induced HeLa cell toxicity, demonstrating the role of secreted factors in the macrophage-mediated effect. Further investigation revealed that CQ induced copper-dependent activation of macrophages and release of tumor necrosis factor (TNF) alpha. In studies with recombinant TNFalpha, we showed that the level of TNFalpha released by CQ-treated macrophages was sufficient to induce HeLa cell toxicity. Moreover, the toxic effect of conditioned medium from CQ-treated macrophages could be prevented by addition of neutralizing antibodies to TNFalpha. These studies demonstrate that CQ can induce cancer cell toxicity through metal-dependent release of TNFalpha from macrophages. Our results may help to explain the targeted inhibition of tumor growth in vivo by CQ.

Antitumor and antiinflammatory effects of tetrathiotungstate in comparison with tetrathiomolybdate

Tetrathiomolybdate (TM) is an anticopper drug under development for treating Wilson's disease. Its mechanism of action involves forming a tight tripartite complex in the blood with serum albumin and available copper. When available copper levels are lowered in animals with TM, strong antiangiogenic and antitumor effects are observed. Similarly, TM has excellent efficacy in animal models of fibrotic, inflammatory, and autoimmune diseases, and it protects against heart damage from doxorubicin (DXR) and liver damage from acetaminophen, carbon tetrachloride, and concanavalin A. Tetrathiotungstate (TT) also forms a similar tripartite complex in the blood and has similar effects to TM on copper. In this article, whether TT had similar antitumor effects, and similar effects in protecting the heart against DXR toxicity, as TM was evaluated. It was found that the 2 drugs were comparable in their effects when doses were used that lowered copper availability to the same extent.

Preadministration of high-dose salicylates, suppressors of NF-kappaB activation, may increase the chemosensitivity of many cancers: an example of proapoptotic signal modulation therapy

NF-kappaB activity is elevated in a high proportion of cancers, particularly advanced cancers that have been treated previously. Cytotoxic treatment selects for such up-regulation inasmuch as NF-kappaB promotes transcription of a large number of proteins that inhibit both the intrinsic and extrinsic pathways of apoptosis; NF-kappaB also boosts expression of mdr1, which expels many drugs from cells. Indeed, high NF-kappaB activity appears to be largely responsible for the chemo- and radioresistance of many cancers. Thus, agents that suppress NF-kappaB activity should be useful as adjuvants to cytotoxic cancer therapy. Of the compounds that are known to be NF-kappaB antagonists, the most practical for current use may be the nonsteroidal anti-inflammatory drugs aspirin, salicylic acid, and sulindac, each of which binds to and inhibits Ikappa kinase- beta, a central mediator of NF-kappa activation; the low millimolar plasma concentrations of salicylate required for effective inhibition of this kinase in vivo can be achieved with high-dose regimens traditionally used to manage rheumatic disorders. The gastrointestinal toxicity of such regimens could be minimized by using salsalate or enteric-coated sodium salicy-late or by administering misoprostol in conjunction with aspirin therapy. Presumably, best results would be seen if these agents were administered for several days prior to a course of chemo- or radiotherapy, continuing throughout the course. This concept should first be tested in nude mice bearing xenografts of chemoresistant human tumors known to have elevated NF-kappa activity. Ultimately, more complex adjuvant regimens can be envisioned in which salicylates are used in conjunction with other NF-kappa antagonists and/or agents that target other mediators of down-regulated apoptosis in cancer, such as Stat3; coadministration of salicylate and organic selenium may have intriguing potential in this regard. These strategies may also have potential as adjuvants to metronomic chemotherapy, which seeks to suppress angio-genesis by targeting cycling endothelial cells in tumors.

Copper binding by tetrathiomolybdate attenuates angiogenesis and tumor cell proliferation through the inhibition of superoxide dismutase 1

PURPOSE

A second-generation tetrathiomolybdate analogue (ATN-224; choline tetrathiomolybdate), which selectively binds copper with high affinity, is currently completing two phase I clinical trials in patients with advanced solid and advanced hematologic malignancies. However, there is very little information about the mechanism of action of ATN-224 at the molecular level.

EXPERIMENTAL DESIGN

The effects of ATN-224 on endothelial and tumor cell growth were evaluated in cell culture experiments in vitro. The antiangiogenic activity of ATN-224 was investigated using the Matrigel plug model of angiogenesis.

RESULTS

ATN-224 inhibits superoxide dismutase 1 (SOD1) in tumor and endothelial cells. The inhibition of SOD1 leads to inhibition of endothelial cell proliferation in vitro and attenuation of angiogenesis in vivo. The inhibition of SOD1 activity in endothelial cells is dose and time dependent and leads to an increase in the steady-state levels of superoxide anions, resulting in the inhibition of extracellular signal-regulated kinase phosphorylation without apparent induction of apoptosis. In contrast, the inhibition of SOD1 in tumor cells leads to the induction of apoptosis. The effects of ATN-224 on endothelial and tumor cells could be substantially reversed using Mn(III)tetrakis(4-benzoic acid)porphyrin chloride, a catalytic small-molecule SOD mimetic.

CONCLUSIONS

These data provide a distinct molecular target for the activity of ATN-224 and provide validation for SOD1 as a target for the inhibition of angiogenesis and tumor growth.

Comparison of lowering copper levels with tetrathiomolybdate and zinc on mouse tumor and doxorubicin models

Tetrathiomolybdate (TM), presumably by lowering copper levels and availability, has shown excellent efficacy in animal models of cancer and models of injury that produce fibrotic or inflammatory damage in lung, heart, and liver. Trials in human patients are underway. If the efficacy of TM is indeed through lowering copper levels, other anticopper drugs should be equally efficacious. Zinc is an anticopper drug, with proven efficacy in Wilson's disease, a disease of copper toxicity. In this study, the efficacy of zinc is compared with TM on a mouse tumor model and on the doxorubicin model of heart damage, and it is hypothesized that when copper availability is lowered to an equivalent extent, the 2 drugs would show equivalent efficacy. No effect is found of zinc on inhibiting growth of a tumor that is markedly inhibited by TM, and zinc is found to be less effective than TM in inhibiting cardiac damage from doxorubicin. This study shows that TM's mechanism of action in protecting against doxorubicin toxicity is because of its anticopper effects, as copper supplementation eliminated the protective effect of TM. It is also hypothesized that the differences between TM and zinc may be caused by TM's mechanism of action in which it binds copper already in the body, whereas zinc does not.

Disulfiram, a Clinically Used Anti-Alcoholism Drug and Copper-Binding Agent, Induces Apoptotic Cell Death in Breast Cancer Cultures and Xenografts via Inhibition of the Proteasome Activity

Disulfiram (DSF), a member of the dithiocarbamate family capable of binding copper and an inhibitor of aldehyde dehydrogenase, is currently being used clinically for the treatment of alcoholism. Recent studies have suggested that DSF may have antitumor and chemosensitizing activities, although the detailed molecular mechanisms remain unclear. Copper has been shown to be essential for tumor angiogenesis processes. Consistently, high serum and tissue levels of copper have been found in many types of human cancers, including breast, prostate, and brain, supporting the idea that copper could be used as a potential tumor-specific target. Here we report that the DSF-copper complex potently inhibits the proteasomal activity in cultured breast cancer MDA-MB-231 and MCF10DCIS.com cells, but not normal, immortalized MCF-10A cells, before induction of apoptotic cancer cell death. Furthermore, MDA-MB-231 cells that contain copper at concentrations similar to those found in patients, when treated with just DSF, undergo proteasome inhibition and apoptosis. In addition, when administered to mice bearing MDA-MB-231 tumor xenografts, DSF significantly inhibited the tumor growth (by 74%), associated with in vivo proteasome inhibition (as measured by decreased levels of tumor tissue proteasome activity and accumulation of ubiquitinated proteins and natural proteasome substrates p27 and Bax) and apoptosis induction (as shown by caspase activation and apoptotic nuclei formation). Our study shows that inhibition of the proteasomal activity can be achieved by targeting tumor cellular copper with the nontoxic compound DSF, resulting in selective apoptosis induction within tumor cells.

The use of tetrathiomolybdate in treating fibrotic, inflammatory, and autoimmune diseases, including the non-obese diabetic mouse model

Tetrathiomolybdate was originally developed for use in Wilson's disease. However, lowering copper levels to below normal levels with tetrathiomolybdate has been found to have efficacy in cancer, probably by turning down signaling by angiogenic cytokines. More recently, we have shown in animals models that tetrathiomolybdate dramatically inhibits pulmonary and liver fibrosis. In other animal models, we have shown that the drug also inhibits liver damage from concanavalin A and acetaminophen, and heart damage from doxorubicin. These studies are briefly reviewed, and we then present data on tetrathiomolybdate's partially protective effect against diabetes in non-obese diabetic mice, an autoimmune model of type I diabetes. Possible mechanisms of tetrathiomolybdate's protective effect are briefly considered.

Potential applications of flat-panel volumetric CT in morphologic and functional small animal imaging

Noninvasive radiologic imaging has recently gained considerable interest in basic and preclinical research for monitoring disease progression and therapeutic efficacy. In this report, we introduce flat-panel volumetric computed tomography (fpVCT) as a powerful new tool for noninvasive imaging of different organ systems in preclinical research. The three-dimensional visualization that is achieved by isotropic high-resolution datasets is illustrated for the skeleton, chest, abdominal organs, and brain of mice. The high image quality of chest scans enables the visualization of small lung nodules in an orthotopic lung cancer model and the reliable imaging of therapy side effects such as lung fibrosis. Using contrast-enhanced scans, fpVCT displayed the vascular trees of the brain, liver, and kidney down to the subsegmental level. Functional application of fpVCT in dynamic contrast-enhanced scans of the rat brain delivered physiologically reliable data of perfusion and tissue blood volume. Beyond scanning of small animal models as demonstrated here, fpVCT provides the ability to image animals up to the size of primates.

Lysyl Oxidase Regulates Breast Cancer Cell Migration and Adhesion through a Hydrogen Peroxide–Mediated Mechanism

We have previously shown that lysyl oxidase (LOX) mRNA is up-regulated in invasive breast cancer cells and that catalytically active LOX facilitates in vitro cell invasion. Here we validate our in vitro studies by showing that LOX expression is up-regulated in distant metastatic breast cancer tissues compared with primary cancer tissues. To elucidate the mechanism by which LOX facilitates cell invasion, we show that catalytically active LOX regulates in vitro motility/migration and cell-matrix adhesion formation. Treatment of the invasive breast cancer cell lines, Hs578T and MDA-MB-231, with beta-aminopropionitrile (betaAPN), an irreversible inhibitor of LOX catalytic activity, leads to a significant decrease in cell motility/migration and adhesion formation. Conversely, poorly invasive MCF-7 cells expressing LOX (MCF-7/LOX32-His) showed an increase in migration and adhesion that was reversible with the addition of betaAPN. Moreover, a decrease in activated focal adhesion kinase (FAK) and Src kinase, key proteins involved in adhesion complex turnover, was observed when invasive breast cancer cells were treated with betaAPN. Additionally, FAK and Src activation was increased in MCF-7/LOX32-His cells, which was reversible on betaAPN treatment. Hydrogen peroxide was produced as a by-product of LOX activity and the removal of hydrogen peroxide by catalase treatment in invasive breast cancer cells led to a dose-dependent loss in Src activation. These results suggest that LOX facilitates migration and cell-matrix adhesion formation in invasive breast cancer cells through a hydrogen peroxide-mediated mechanism involving the FAK/Src signaling pathway. These data show the need to target LOX for treatment of aggressive breast cancer.

The role of copper in tumour angiogenesis

Copper stimulates the proliferation and migration of endothelial cells and is required for the secretion of several angiogenic factors by tumour cells. Copper chelation decreases the secretion of many of these factors. Serum copper levels are upregulated in many human tumours and correlate with tumour burden and prognosis. Copper chelators reduce tumour growth and microvascular density in animal models. New orally active copper chelators have enabled clinical trials to be undertaken, and there are several studies ongoing. A unifying mechanism of action by which copper chelation inhibits endothelial cell proliferation and tumour secretion of angiogenic factors remains to be elucidated, but possible targets include copper-dependent enzymes, chaperones, and transporters.