Heather Hatcher

Curcumin: from ancient medicine to current clinical trials.

Abstract.Curcumin is the active ingredient in the traditional herbal remedy and dietary spice turmeric (Curcuma longa). Curcumin has a surprisingly wide range of beneficial properties, including anti-inflammatory, antioxidant, chemopreventive and chemotherapeutic activity. The pleiotropic activities of curcumin derive from its complex chemistry as well as its ability to influence multiple signaling pathways, including survival pathways such as those regulated by NF-κB, Akt, and growth factors; cytoprotective pathways dependent on Nrf2; and metastatic and angiogenic pathways. Curcumin is a free radical scavenger and hydrogen donor, and exhibits both pro- and antioxidant activity. It also binds metals, particularly iron and copper, and can function as an iron chelator. Curcumin is remarkably non-toxic and exhibits limited bioavailability. Curcumin exhibits great promise as a therapeutic agent, and is currently in human clinical trials for a variety of conditions, including multiple myeloma, pancreatic cancer, myelodysplastic syndromes, colon cancer, psoriasis and Alzheimer’s disease.

Long-term survival following a single treatment of kidney tumors with multiwalled carbon nanotubes and near-infrared radiation

Multiwalled carbon nanotubes (MWCNTs) exhibit physical properties that render them ideal candidates for application as noninvasive mediators of photothermal cancer ablation. Here, we demonstrate that use of MWCNTs to generate heat in response to near-infrared radiation (NIR) results in thermal destruction of kidney cancer in vitro and in vivo. We document the thermal effects of the therapy through magnetic resonance temperature-mapping and heat shock protein-reactive immunohistochemistry. Our results demonstrate that use of MWCNTs enables ablation of tumors with low laser powers (3 W/cm2) and very short treatment times (a single 30-sec treatment) with minimal local toxicity and no evident systemic toxicity. These treatment parameters resulted in complete ablation of tumors and a >3.5-month durable remission in 80% of mice treated with 100 μg of MWCNT. Use of MWCNTs with NIR may be effective in anticancer therapy.

Ferroportin and Iron Regulation in Breast Cancer Progression and Prognosis

Ferroportin and hepcidin are critical proteins for the regulation of systemic iron homeostasis. Ferroportin is the only known mechanism for export of intracellular non-heme-associated iron; its stability is regulated by the hormone hepcidin. Although ferroportin profoundly affects concentrations of intracellular iron in tissues important for systemic iron absorption and trafficking, ferroportin concentrations in breast cancer and their influence on growth and prognosis have not been examined. We demonstrate here that both ferroportin and hepcidin are expressed in cultured human breast epithelial cells and that hepcidin regulates ferroportin in these cells. Further, ferroportin protein is substantially reduced in breast cancer cells compared to nonmalignant breast epithelial cells; ferroportin protein abundance correlates with metabolically available iron. Ferroportin protein is also present in normal human mammary tissue and markedly decreased in breast cancer tissue, with the highest degree of anaplasia associated with lowest ferroportin expression. Transfection of breast cancer cells with ferroportin significantly reduces their growth after orthotopic implantation in the mouse mammary fat pad. Gene expression profiles in breast cancers from >800 women reveal that decreased ferroportin gene expression is associated with a significant reduction in metastasis-free and disease-specific survival that is independent of other breast cancer risk factors. High ferroportin and low hepcidin gene expression identifies an extremely favorable cohort of breast cancer patients who have a 10-year survival of >90%. Ferroportin is a pivotal protein in breast biology and a strong and independent predictor of prognosis in breast cancer.

Curcumin, a cancer chemopreventive and chemotherapeutic agent, is a biologically active iron chelator

Curcumin is a natural product currently in human clinical trials for a variety of neoplastic, preneoplastic, and inflammatory conditions. We previously observed that, in cultured cells, curcumin exhibits properties of an iron chelator. To test whether the chelator activity of curcumin is sufficient to induce iron deficiency in vivo, mice were placed on diets containing graded concentrations of both iron and curcumin for 26 weeks. Mice receiving the lowest level of dietary iron exhibited borderline iron deficiency, with reductions in spleen and liver iron, but little effect on hemoglobin, hematocrit, transferrin saturation, or plasma iron. Against this backdrop of subclinical iron deficiency, curcumin exerted profound 2 effects on systemic iron, inducing a dose-dependent decline in hematocrit, hemoglobin, serum iron, and transferrin saturation, the appearance of microcytic anisocytotic red blood cells, and decreases in spleen and liver iron content. Curcumin repressed synthesis of hepcidin, a peptide that plays a central role in regulation of systemic iron balance. These results demonstrate that curcumin has the potential to affect systemic iron metabolism, particularly in a setting of subclinical iron deficiency. This may affect the use of curcumin in patients with marginal iron stores or those exhibiting the anemia of cancer and chronic disease.

Photothermal Response of Human and Murine Cancer Cells to Multiwalled Carbon Nanotubes after Laser Irradiation

This study demonstrates the capability of multiwalled carbon nanotubes (MWNTs) coupled with laser irradiation to enhance treatment of cancer cells through enhanced and more controlled thermal deposition, increased tumor injury, and diminished heat shock protein (HSP) expression. We also explored the potential promise of MWNTs as drug delivery agents by observing the degree of intracellular uptake of these nanoparticles. To determine the heat generation capability of MWNTs, the absorption spectra and temperature rise during heating were measured. Higher optical absorption was observed for MWNTs in water compared with water alone. For identical laser parameters, MWNT-containing samples produced a significantly greater temperature elevation compared to samples treated with laser alone. Human prostate cancer (PC3) and murine renal carcinoma (RENCA) cells were irradiated with a 1,064-nm laser with an irradiance of 15.3 W/cm(2) for 2 heating durations (1.5 and 5 minutes) alone or in combination with MWNT inclusion. Cytotoxicity and HSP expression following laser heating was used to determine the efficacy of laser treatment alone or in combination with MWNTs. No toxicity was observed for MWNTs alone. Inclusion of MWNTs dramatically decreased cell viability and HSP expression when combined with laser irradiation. MWNT cell internalization was measured using fluorescence and transmission electron microscopy following incubation of MWNTs with cells. With increasing incubation duration, a greater number of MWNTs were observed in cellular vacuoles and nuclei. These findings offer an initial proof of concept for the application of MWNTs in cancer therapy.

Synthetic and natural iron chelators: therapeutic potential and clinical use.

Iron-chelation therapy has its origins in the treatment of iron-overload syndromes. For many years, the standard for this purpose has been deferoxamine. Recently, considerable progress has been made in identifying synthetic chelators with improved pharmacologic properties relative to deferoxamine. Most notable are deferasirox (Exjade(®)) and deferiprone (Ferriprox(®)), which are now available clinically. In addition to treatment of iron overload, there is an emerging role for iron chelators in the treatment of diseases characterized by oxidative stress, including cardiovascular disease, atherosclerosis, neurodegenerative diseases and cancer. While iron is not regarded as the underlying cause of these diseases, it does play an important role in disease progression, either through promotion of cellular growth and proliferation or through participation in redox reactions that catalyze the formation of reactive oxygen species and increase oxidative stress. Thus, iron chelators may be of therapeutic benefit in many of these conditions. Phytochemicals, many of which bind iron, may also owe some of their beneficial properties to iron chelation. This review will focus on the advances in iron-chelation therapy for the treatment of iron-overload disease and cancer, as well as neurodegenerative and chronic inflammatory diseases. Established and novel iron chelators will be discussed, as well as the emerging role of dietary plant polyphenols that effectively modulate iron biochemistry.

IRP2 Regulates Breast Tumor Growth

Experimental and epidemiologic evidence suggests that dysregulation of proteins involved in iron metabolism plays a critical role in cancer. The mechanisms by which cancer cells alter homeostatic iron regulation are just beginning to be understood. Here, we demonstrate that iron regulatory protein 2 (IRP2) plays a key role in iron accumulation in breast cancer. Although both IRP1 and IRP2 are overexpressed in breast cancer, the overexpression of IRP2, but not IRP1, is associated with decreased ferritin H and increased transferrin receptor 1 (TfR1). Knockdown of IRP2 in triple-negative MDA-MB-231 human breast cancer cells increases ferritin H expression and decreases TfR1 expression, resulting in a decrease in the labile iron pool. Further, IRP2 knockdown reduces growth of MDA-MB-231 cells in the mouse mammary fat pad. Gene expression microarray profiles of patients with breast cancer demonstrate that increased IRP2 expression is associated with high-grade cancer. Increased IRP2 expression is observed in luminal A, luminal B, and basal breast cancer subtypes, but not in breast tumors of the ERBB2 molecular subtype. These results suggest that dysregulation of IRP2 is an early nodal point underlying altered iron metabolism in breast cancer and may contribute to poor outcome of some patients with breast cancer.

Yin yang 1 plays an essential role in breast cancer and negatively regulates p27

Yin Yang 1 (YY1) is highly expressed in various types of cancers and regulates tumorigenesis through multiple pathways. In the present study, we evaluated YY1 expression levels in breast cancer cell lines, a breast cancer TMA, and two gene arrays. We observed that, compared with normal samples, YY1 is generally overexpressed in breast cancer cells and tissues. In functional studies, depletion of YY1 inhibited the clonogenicity, migration, invasion, and tumor formation of breast cancer cells, but did not affect the clonogenicity of nontumorigenic cells. Conversely, ectopically expressed YY1 enhanced the migration and invasion of nontumorigenic MCF-10A breast cells. In both a monolayer culture condition and a three-dimensional Matrigel system, silenced YY1 expression changed the architecture of breast cancer MCF-7 cells to that resembling MCF-10A cells, whereas ectopically expressed YY1 in MCF-10A cells had the opposite effect. Furthermore, we detected an inverse correlation between YY1 and p27 expression in both breast cancer cells and xenograft tumors with manipulated YY1 expression. Counteracting the changes in p27 expression attenuated the effects of YY1 alterations on these cells. In addition, YY1 promoted p27 ubiquitination and physically interacted with p27. In conclusion, our data suggest that YY1 is an oncogene and identify p27 as a new target of YY1.

Development of iron-containing multiwalled carbon nanotubes for MR-guided laser-induced thermotherapy

AIMS To test iron-containing multiwalled carbon nanotubes (MWCNTs) as bifunctional nanomaterials for imaging and thermal ablation of tumors. MATERIALS & METHODS MWCNTs entrapping iron were synthesized by chemical vapor deposition. The T2-weighted contrast enhancement properties of MWCNTs containing increasing amounts of iron were determined in vitro. Suspensions of these particles were injected into tumor-bearing mice and tracked longitudinally over 7 days by MRI. Heat-generating abilities of these nanomaterials following exposure to near infrared (NIR) laser irradiation was determined in vitro and in vivo. RESULTS The magnetic resonance contrast properties of carbon nanotubes were directly related to their iron content. Iron-containing nanotubes were functional T2-weighted contrast agents in vitro and could be imaged in vivo long-term following injection. Iron content of nanotubes did not affect their ability to generate thermoablative temperatures following exposure to NIR and significant tumor regression was observed in mice treated with MWCNTs and NIR laser irradiation. CONCLUSION These data demonstrate that iron-containing MWCNTs are functional T2-weighted contrast agents and efficient mediators of tumor-specific thermal ablation in vivo.

Ferritin Blocks Inhibitory Effects of Two-Chain High Molecular Weight Kininogen (HKa) on Adhesion and Survival Signaling in Endothelial Cells

Angiogenesis is tightly regulated through complex crosstalk between pro- and anti-angiogenic signals. High molecular weight kininogen (HK) is an endogenous protein that is proteolytically cleaved in plasma and on endothelial cell surfaces to HKa, an anti-angiogenic protein. Ferritin binds to HKa and blocks its anti-angiogenic activity. Here, we explore mechanisms underlying the cytoprotective effect of ferritin in endothelial cells exposed to HKa. We observe that ferritin promotes adhesion and survival of HKa-treated cells and restores key survival and adhesion signaling pathways mediated by Erk, Akt, FAK and paxillin. We further elucidate structural motifs of both HKa and ferritin that are required for effects on endothelial cells. We identify an histidine-glycine-lysine (HGK) -rich antiproliferative region within domain 5 of HK as the target of ferritin, and demonstrate that both ferritin subunits of the H and L type regulate HKa activity. We further demonstrate that ferritin reduces binding of HKa to endothelial cells and restores the association of uPAR with α5β1 integrin. We propose that ferritin blocks the anti-angiogenic activity of HKa by reducing binding of HKa to UPAR and interfering with anti-adhesive and anti-proliferative signaling of HKa.