Different tissue responses for iodine and iodide in rat thyroid and mammary glands

Iodine loaded nanoparticles with commercial applicability increase survival in mice cancer models with low degree of side effects

BACKGROUND

The recorded use of iodine in medicine, dates to 5000 BC. Molecular iodine (I2 ) has been claimed to exert an antineoplastic effect that triggers apoptotic and re-differentiation mechanisms in different types of cancer cells in animal studies. Hitherto, all experiments published have been carried out with I2 diluted in water preparations resulting in the administration of ionized iodide, either alone or in combination with low levels of I2 . To maximize the levels of I2 by avoiding water solutions we have managed to develop a colloidal nano particle (NP) loaded with I2 with a Z-average of 7-23 nm with remarkable stability, preferable osmolality and commercial applicability.

AIMS

Here we report the results from formulation and pre-clinical studies with the rationale: a) to find a tolerable dose of the I2 NP system delivered intravenously or per-orally, and b) to determine if the tolerable doses are efficacious in murine models of cancer.

METHODS AND RESULTS

A novel drug delivery system with I2 NP was formulated and murine cancer models with CT26, MDA-MB-231 and LL/2 cells were used to analyse the efficacy. Despite the formulation challenges we were successful in constructing stable NPs loaded with I2 which have convincing commercial applicability. We conclude that administration of the NP I2 drug delivery system: 1. Blunted tumour growth in a xenograft breast cancer model; 2. Had a significant effect on survival in the orthotopic, syngeneic lung metastasis model; 3. Showed reduced tumour burden in post-mortem evaluation and; 4. Was associated with low degree of side effects.

CONCLUSIONS

Taken all together, our findings indicate that the NP I2 drug delivery system may serve as a novel effective cancer treatment with low degree of side effects. This is something which needs further exploration including confirmation in future clinical trials.

Adversity Considerations for Thyroid Follicular Cell Hypertrophy and Hyperplasia in Nonclinical Toxicity Studies: Results From the 6th ESTP International Expert Workshop

The European Society of Toxicologic Pathology organized an expert workshop in May 2018 to address adversity considerations related to thyroid follicular cell hypertrophy and/or hyperplasia (FCHH), which is a common finding in nonclinical toxicity studies that can have important implications for risk assessment of pharmaceuticals, food additives, and environmental chemicals. The broad goal of the workshop was to facilitate better alignment in toxicologic pathology and regulatory sciences on how to determine adversity of FCHH. Key objectives were to describe common mechanisms leading to thyroid FCHH and potential functional consequences; provide working criteria to assess adversity of FCHH in context of associated findings; and describe additional methods and experimental data that may influence adversity determinations. The workshop panel was comprised of representatives from the European Union, Japan, and the United States. Participants shared case examples illustrating issues related to adversity assessments of thyroid changes. Provided here are summary discussions, key case presentations, and panel recommendations. This information should increase consistency in the interpretation of adverse changes in the thyroid based on pathology findings in nonclinical toxicity studies, help integrate new types of biomarker data into the review process, and facilitate a more systematic approach to communicating adversity determinations in toxicology reports.

Molecular Iodine Has Extrathyroidal Effects as an Antioxidant, Differentiator, and Immunomodulator

Most investigations of iodine metabolism in humans and animals have focused on its role in thyroid function. However, considerable evidence indicates that iodine could also be implicated in the physiopathology of other organs. We review the literature that shows that molecular iodine (I₂) exerts multiple and complex actions on the organs that capture it, not including its effects as part of thyroid hormones. This chemical form of iodine is internalized by a facilitated diffusion system that is evolutionary conserved, and its effects appear to be mediated by a variety of mechanisms and pathways. As an oxidized component, it directly neutralizes free radicals, induces the expression of type II antioxidant enzymes, or inactivates proinflammatory pathways. In neoplastic cells, I₂ generates iodolipids with nuclear actions that include the activation of apoptotic pathways and the inhibition of markers related to stem cell maintenance, chemoresistance, and survival. Recently, I2 has been postulated as an immune modulator that depending on the cellular context, can function as an inhibitor or activator of immune responses. We propose that the intake of molecular iodine is increased in adults to at least 1 mg/day in specific pathologies to obtain the potential extrathyroid benefits described in this review.

Serum Iodine and Breast Cancer Risk: A Prospective Nested Case-Control Study Stratified for Selenium Levels

BACKGROUND

Iodine has been suggested to protect against breast cancer, but there are no epidemiologic studies on individual risk. An interesting finding is that in areas where the exposure to both selenium and iodine are high (e.g., Japan), the risk of breast cancer is lower than in areas where selenium is high and iodine low (e.g., United States), or in areas where both are low (e.g., Northern Europe). The aim of this study was to investigate the association between prediagnostic serum iodine levels and subsequent breast cancer risk, and to investigate if this potential association was modified by selenium levels.

METHODS

The Malmö Diet and Cancer Study provided prediagnostic serum samples and the current analysis included 1,159 breast cancer cases and 1,136 controls. Levels of baseline serum iodine and selenium were analyzed. A logistic regression analysis yielded ORs with 95% confidence intervals adjusted for potential confounders.

RESULTS

There was no evidence of an overall association between iodine levels and risk of breast cancer. Among women with high selenium levels (above the median), high iodine levels were associated with a lower risk of breast cancer; the OR for above versus below the median was 0.75 (0.57-0.99). The corresponding OR for women with low selenium was 1.15 (0.87-1.50), and the P _interaction was 0.06.

CONCLUSIONS

The combination of high serum iodine levels and high selenium levels was associated with a lower risk of breast cancer.

IMPACT

A high iodine and selenium exposure may decrease the risk of breast cancer.

The antigenic link between thyroid autoimmunity and breast cancer

The association between breast cancer and benign thyroid disorders, in particular thyroid autoimmunity, has been debated for decades. Autoantibodies to thyroid peroxidase, the hallmark of thyroid autoimmunity, have a higher prevalence among patients with breast cancer compared with the general population. Furthermore a correlation between their positivity and a better prognosis of breast cancer was found in several independent small-scale studies, even if such observation was not confirmed in a subsequent retrospective study conducted on the largest patient cohort to date. The thyroid and mammary glands present several biological similarities, therefore the hypothesis of an immune response to shared thyroid/breast antigens could in part explain the association between thyroid autoimmunity and breast cancer. The sodium iodide symporter is expressed in both glands, however it seems unlikely to be the key common antigen, considering that autoantibodies targeting it are rare. Instead thyroid peroxidase, one of the major thyroid autoantigens, is also expressed in breast tissue and therefore represents the main antigenic link between thyroid autoimmunity and breast cancer. Furthermore lactoperoxidase, an enzyme of the same family that shares structural similarities with thyroid peroxidase, is expressed in neoplastic breast cells and is responsible for the cross-reactivity with some autoantibodies to thyroid peroxidase. Novel strategies for the diagnosis and treatment of breast cancer might take advantage of the antigenic link between thyroid and breast tissues.

Role of iodide metabolism in physiology and cancer

Iodide (I^-) metabolism is crucial for the synthesis of thyroid hormones (THs) in the thyroid and the subsequent action of these hormones in the organism. I^- is principally transported by the sodium iodide symporter (NIS) and by the anion exchanger PENDRIN, and recent studies have demonstrated the direct participation of new transporters including anoctamin 1 (ANO1), cystic fibrosis transmembrane conductance regulator (CFTR) and sodium multivitamin transporter (SMVT). Several of these transporters have been found expressed in various tissues, implicating them in I^- recycling. New research supports the exciting idea that I^- participates as a protective antioxidant and can be oxidized to hypoiodite, a potent oxidant involved in the host defense against microorganisms. This was possibly the original role of I^- in biological systems, before the appearance of TH in evolution. I^- per se participates in its own regulation, and new evidence indicates that it may be antineoplastic, anti-proliferative and cytotoxic in human cancer. Alterations in the expression of I^- transporters are associated with tumor development in a cancer-type-dependent manner and, accordingly, NIS, CFTR and ANO1 have been proposed as tumor markers. Radioactive iodide has been the mainstay adjuvant treatment for thyroid cancer for the last seven decades by virtue of its active transport by NIS. The rapid advancement of techniques that detect radioisotopes, in particular I^-, has made NIS a preferred target-specific theranostic agent.

The correlation between breast cancer and urinary iodine excretion levels

Objective

To compare urinary iodine excretion levels in patients with breast cancer and control subjects.

Methods

In this prospective pilot study, patients with breast cancer and normal controls were recruited. Age and menopausal status were recorded. Levels of serum thyroid-stimulating hormone, blood urea nitrogen and creatinine and urine iodine concentration (UIC) were measured. UIC levels were divided into three categories: low (<100 µg/l), normal (100–200 µg/l) or high (>200 µg/l).

Results

A total of 24 patients with breast cancer and 48 controls were included in the study. There were no statistically significant differences between the two groups with regard to thyroid-stimulating hormone, blood urea nitrogen or creatinine levels. When considered overall, there was no statistical difference in UIC between patients and controls. However, comparisons within each category (low, normal or high UIC) showed a significantly higher percentage of patients with breast cancer had a high UIC compared with controls.

Conclusions

A high UIC was seen in a significantly higher percentage of patients with breast cancer than controls. UIC may have a role as a marker for breast cancer screening. Further studies evaluating UIC and iodine utilization in patients with breast cancer are warranted.

Investigation of the Halogenate-Hydrogen Peroxide Reactions Using the Electron Paramagnetic Resonance Spin Trapping Technique

The differences in the mechanism of the halogenate reactions with the same oxidizing/reducing agent, such as H₂O₂ contribute to the better understanding of versatile halogen chemistry. The reaction between iodate, bromate, and chlorate with hydrogen peroxide in acidic medium at 60 °C is investigated by using the electron paramagnetic resonance (EPR) spin trapping technique. Essential differences in the chemistry of iodate, bromate, and chlorate in their reactions with hydrogen peroxide have been evidenced by finding different radicals as governing intermediates. The reaction between KIO₃ and H₂O₂ is supposed to be the source of IO₂^• radicals. The KBrO₃ and H₂O₂ reaction did not produce any EPR signal, whereas the KClO₃-H₂O₂ system was found to be a source of HO^• radical. Moreover, KClO₃ dissolved in sulfuric acid without hydrogen peroxide produced HO^• radical as well. The minimal-core models explaining the origin of obtained EPR signals are proposed. Current findings suggested the inclusion of IO₂^• and HOO^• radicals, and ClO₂^• and HO^• radicals in the particular kinetic models of iodate-hydrogen peroxide and chlorate-hydrogen peroxide systems, as well as possible exclusion of BrO₂^• radical from the kinetic scheme of the bromate-hydrogen peroxide system. Obtained results may pave the way for understanding more complex, nonlinear reactions of these halogen-containing species.

The thyroid and breast cancer

PURPOSE OF REVIEW

The female predominance of diseases of the thyroid and breast makes difficult the separation of an expected association with a causal linkage. This review will examine recent reports on associations between thyroid disease and breast cancer, comparing them with previous studies, with a view to elucidating what pointers are available to suggest either a common pathogenesis or novel thyroid-related therapeutic approach, which might arise from this association.

RECENT FINDINGS

Reports on thyroid-breast cancer associations are reviewed under the following headings: breast cancer prevalence in different thyroid disorders and their effect on risk and outcome; the possible role of thyroid autoimmunity, thyroid enlargement, effect of radioactive iodine treatment, role of stable iodine, possible joint antigens sodium iodide transporter and thyroid peroxidase and thyroid-breast cancer coincidence.

SUMMARY

Current studies on thyroid and breast cancer associations confirm earlier findings of the lack of definitive evidence of a causal relationship. The predominant relationship continues to be hypothyroidism or autoimmune thyroid disease perhaps contributing to increased breast cancer risk or outcomes. However, despite many studies and the findings of meta-analyses, elucidating the mechanisms underlying the association remains elusive. At present, there is little justification for utilizing thyroid insights as a possible therapeutic intervention in breast cancer.

Antiproliferative/cytotoxic effects of molecular iodine, povidone-iodine and Lugol's solution in different human carcinoma cell lines

Clinical trials have revealed that molecular iodine (I₂) has beneficial effects in fibrocystic breast disease and in cyclic mastalgia. Likewise, povidone-iodine (PVP-I), which is widely used in clinical practice as an antiseptic agent following tumour surgery, has been demonstrated to have cytotoxic effects on colon cancer and ascites tumour cells. Our previous study indicated that the growth of breast cancer and seven other human malignant cell lines was variably diminished by I₂ and iodolactones. With the intention of developing an iodine-based anticancer therapy, the present investigations extended these studies by comparing the cytotoxic capacities of I₂, potassium iodide (KJ), PVP-I and Lugol's solution on various human carcinoma cell lines. Upon staining the cell nuclei with Hoechst 33342, the cell densities were determined microscopically. While KJ alone did not affect cell proliferation, it enhanced the antiproliferative activity of I₂. In addition, PVP-I significantly inhibited the proliferation of human MCF-7 breast carcinoma, IPC melanoma, and A549 and H1299 lung carcinoma cells in a concentration corresponding to 20 µM I₂. Likewise, Lugol's solution in concentrations corresponding to 20-80 µM I₂ were observed to reduce the growth of MCF-7 cells. Experiments with fresh human blood samples revealed that the antiproliferative activity of PVP-I and I₂ is preserved in blood plasma to a high degree. These findings suggest that PVP-I, Lugol's solution, and a combination of iodide and I₂ may be potent agents for use in the development of antitumour strategies.

Activation of peroxisome proliferator-activated receptor gamma is crucial for antitumoral effects of 6-iodolactone

BACKGROUND

Molecular iodine (I2) exhibits antiproliferative and apoptotic effects on in vivo and in vitro cancer models. These effects are thought to be mediated by an iodinated arachidonic acid derivative, 6-iodolactone (6IL), and one of the proposed mechanisms is that 6IL activates Peroxisome Proliferator-Activated Receptors type gamma (PPARG). These receptors have been implicated in the inhibition of carcinogenic processes, in addition to their classical role in maintaining lipid and glucose homeostasis. The aim of this study was to determine whether PPARG participates in the 6IL antiproliferative and apoptotic effects on the mammary cancer cell line MCF-7.

METHODS

The 6IL/PPARG complex was inhibited by the PPARG antagonist GW9662, in both an endogenous and overexpressed (adenoviral vector infection) context, and stable PPARG-knockdown MCF-7 cells (RNA interference, confirmed with hydrolysis probes and Western blot), were used to corroborate the PPARG participation. 6IL effects on proliferation (measured by Trypan Blue exclusion) and apoptosis (phosphatidylserine identification by flow cytometer) were evaluated in conditions of chemical inhibition (GW9662) and silencing (RNA interference). A wound-healing assay was conducted on wild-type and stable PPARG-knockdown MCF-7 cells to evaluate the antimigrational effect of 6IL. Caspase-8 activity was evaluated to determine if the extrinsic pathway is involved in the effects of 6IL and I2 treatment.

RESULTS

Antiproliferative and pro-apoptotic 6IL effects require the activation of PPARG. In addition, wound-healing assays show that 6IL is able to inhibit MCF-7 cell migration and that PPARG plays a role in this phenomenon. Finally, the data exclude the participation of the extrinsic apoptotic pathway in 6IL- and I2-induced apoptosis.

CONCLUSIONS

These results support the previously proposed mechanism, in which the I2 effects are mediated by 6IL, and they provide further support for the use of I2 as coadjuvant in breast cancer treatment.

Total iodine quantification in fluids and tissues from iodine- or iodide-supplemented rats by ion chromatography following microwave-assisted digestion

BACKGROUND

Iodine is a crucial component of thyroid hormones, and several reports have shown that iodine per se is implicated in the physiopathology of other organs.

METHODS

Innovative ion chromatography detection following a four-step temperature ramp microwave digestion in 25-50 mM nitric acid was developed to measure total iodine in biological fluids and tissue samples from female Sprague-Dawley rats supplemented with 0.05% molecular iodine (I2) or 0.05% potassium iodide (I(-)) in drinking water.

RESULTS

The reported method allows the measurement of total iodine with a limit of quantification of 13.7 μg L(-1), recoveries of 96.3-100.3%, and intra- and inter-assay variations, of 3.5% and 7.4% respectively. Analysis of biological fluids showed that after 48 hours, iodine-supplemented animals exhibited significantly higher levels of total iodine in both serum and urine compared with those supplemented with iodide. The half-life of iodine in serum and urine measured over the first 48 h showed similar patterns for both the I2 (7.89 and 7.76 hours) and I(-) (8.27 and 8.90 hours) supplements. Differential uptake patterns were observed in tissues after 6 days of supplements, with I(-) preferentially retained by thyroid, lactating mammary gland, and milk, and a slightly but significantly higher capture of I2 in pituitary, ovary, and virgin mammary gland.

CONCLUSIONS

We developed a rapid, selective, and accurate digestion method to process fluid and tissue samples that permits reproducible measurements of total iodine by ion chromatography; iodine or iodide supplement show a similar serum and urine half-life, but organ-specific uptake depends on the chemical form of the iodine supplement.

Effects of laver extracts on adhesion, invasion, and migration in SK-Hep1 human hepatoma cancer cells

The laver (Porphyra tenera), red seaweed, has been reported to have anticancer activity, but little is known about its molecular mechanisms of action. The objective of this study was to determine the effects of laver extract on cancer cell proliferation, invasion, and metastasis in SK-Hep1 cells using migration and invasion assays. We also investigated the relationship of MMP-2/-9 and TIMP-1/-2 expression at both the protein and gene level in SK-Hep1 human hepatoma carcinoma cells after laver extract treatment. Laver extract inhibited cancer cell growth in a dose-dependent manner. In an invasion assay conducted in Transwell chambers, laver extract showed 19.6 and 27.2% inhibition of cancer cell at 200 and 400 μg/mL, respectively, compared to the control. The mRNA levels of both MMP-2 and MMP-9 were down-regulated by laver extract treatment in a dose-dependent manner. Laver extract, at 400 μg/mL, was inhibited by MMP-2 and MMP-9 expressions by 70.1 and 77.0%, respectively. An inverse relationship in the mRNA contents of MMP-2/-9 and TIMP-1/-2 expressions in SK-Hep1 cells was found by laver extract treatment. Our results demonstrate antimetastatic properties of laver extract in inhibiting the adhesion, invasion, and migration of SK-Hep1 human hepatoma cancer cells.

Comparison of tamoxifen with edible seaweed (Eucheuma cottonii L.) extract in suppressing breast tumor

The tropical edible red seaweed (Eucheuma cottonii L.) is rich in nutrients and polyphenolic compounds that may suppress cancer through its antioxidant and antiproliferative properties. The study reports on rat mammary tumor suppression and tissue antioxidant status modulation by E. cottonii ethanol extract (ECE). The effect of orally administered ECE (100 mg/kg body-weight) was compared with that of tamoxifen (10 mg/kg body-weight). Rat was induced to develop mammary tumor with subcutaneous injection of LA-7 cells (6 × 10(6) cells/rat). The ECE was more effective than tamoxifen in suppressing tumor growth (27%), improving tissues (plasma, liver, and kidney) malondialdehyde concentrations, superoxide dismutase activity and erythrocyte glutathione concentrations (P < 0.05). Unlike tamoxifen, the ECE displayed little toxicity to the liver and kidneys. The ECE exhibited strong anticancer effect with enzyme modulating properties, suggesting its potential as a suppressing agent for mammary gland tumor.

Protective effect of edible marine algae, Laminaria japonica and Porphyra haitanensis, on subchronic toxicity in rats induced by inorganic arsenic

Arsenic, a potent environmental toxic agent, causes various hazardous effects on human health. This study was performed to evaluate the protective effects of edible marine algae, Laminaria japonica and Porphyra haitanensis, on subchronic stress of rats induced by arsenic trioxide (As2O3). The co-treatment of marine algae could slightly increase the growth rates of body weights compared to the As2O3-treated group. The marine algae application restored liver and renal function by preventing the increment in the activities of alanine transaminase and alkaline phosphatase, and the levels of total protein, blood urea nitrogen, and creatinine. The increase in the contents of total cholesterol, triglyceride, and low density lipoprotein cholesterol, and decrease in the contents of high density lipoprotein cholesterol were observed in algae co-treated groups which indicated that marine algae could reverse the abnormal lipid metabolisms induced by arsenic. Moreover, these algae could protect the rats from lipid peroxidation by restoring the depletion of superoxide dismutase and glutathione peroxidase activities and sulfhydryl group contents, and lowering the enhanced malondialdehyde contents. Therefore, evidences indicate that L. japonica and P. haitanensis can serve as an effective regimen for treating arsenic poisoning.

The extrathyronine actions of iodine as antioxidant, apoptotic, and differentiation factor in various tissues

BACKGROUND

Seaweed is an important dietary component and a rich source of iodine in several chemical forms in Asian communities. Their high consumption of this element (25 times higher than in Western countries) has been associated with the low incidence of benign and cancerous breast and prostate disease in Japanese people.

SUMMARY

We review evidence showing that, in addition to being a component of the thyroid hormone, iodine can be an antioxidant as well as an antiproliferative and differentiation agent that helps to maintain the integrity of several organs with the ability to take up iodine. In animal and human studies, molecular iodine (I2) supplementation exerts a suppressive effect on the development and size of both benign and cancerous neoplasias. Investigations by several groups have demonstrated that these effects can be mediated by a variety of mechanisms and pathways, including direct actions, in which the oxidized iodine dissipates the mitochondrial membrane potential, thereby triggering mitochondrion-mediated apoptosis, and indirect effects through iodolipid formation and the activation of peroxisome proliferator-activated receptors type gamma, which, in turn, trigger apoptotic or differentiation pathways.

CONCLUSIONS

We propose that the International Council for the Control of Iodine Deficient Disorders recommend that iodine intake be increased to at least 3 mg/day of I2 in specific pathologies to obtain the potential extrathyroidal benefits described in the present review.

Mechanisms in endocrinology: primary HT and risk for breast cancer: a systematic review and meta-analysis

OBJECTIVE

The association between hypothyroidism and breast cancer has been described from very early on. Breast and thyroid tissue are interconnected on a molecular level mainly through activation of thyroid hormone receptors expressed on cells of the mammary gland as well as on the plasma membrane of breast cancer cells. Despite the experimental evidence the true value of hypothyroidism as a risk factor for breast cancer remains controversial.

METHODS

We searched the PubMed database through February 2011 to identify studies that evaluated the association between hypothyroidism and risk for breast cancer as well as the effect of thyroid hormone replacement therapy on breast cancer incidence.

RESULTS

A meta-analysis performed in 12 studies showed that hypothyroidism was not associated with risk for breast cancer (pooled risk ratio (RR)=1.06, 95% confidence intervals (CIs) 0.82-1.35, P = 0.672). The effect of treatment was assessed in seven studies and no evidence for an association between thyroid hormone replacement and breast cancer was observed with an overall RR of 0.99 (95% CI 0.73-1.35, P = 0.965).

CONCLUSIONS

Our meta-analysis showed that hypothyroidism is not associated with increased risk for breast cancer and thyroid hormone replacement therapy does not reduce breast cancer prevalence; however, the heterogeneity of the studies analyzed precludes firm conclusions.

Lead exposure: a contributing cause of the current breast cancer epidemic in Nigerian women

Breast cancer incidence in Nigerian women has significantly increased during the past three decades in parallel with the rapid industrialization of that country. This suggested that the associated widespread contamination of the soil and of the water supplies by lead (Pb) and other industrial metals was a major contributing cause. Because of its many domestic, industrial, and automotive uses, Pb is of particular concern as it has been shown to promote the development of mammary tumors in murine mammary tumor virus-infected female C3H mice at levels as low of 0.5 ppm Pb in the drinking water. Lead belongs to the group of selenium-antagonistic elements that interact with selenium (Se), abolishing its anti-carcinogenic effect. Lead on chronic, low-level exposure in addition also accelerates tumor growth rates. Higher levels of Pb were found in blood and head hair samples of newly diagnosed patients with breast cancer, all with infiltrating ductal carcinoma, the most common form of breast cancer in Nigeria, seen at Obafemi Awolowo University, than in cancer-free controls from the same area. Evidence for interactions between Pb and Se was obtained from blood, hair, and tumor biopsy tissue analyses. Furthermore, the Pb levels in hair samples of the patients were directly correlated with the volumes of their tumors, in accord with the tumor growth-promoting effects of Pb. Conversely, Se levels in hair and blood were inversely correlated with the tumor volumes, consistent with the anti-proliferative effects of Se. Several other elements, e.g., Cd, Hg, Cr, Sn, and As, were detected in the scalp hair of the patients and the controls, although at significantly lower levels than those of Pb. However, correlation calculations revealed them also to interact with Se, suggesting that only a fraction of the Se in organs and tissues is actually present in bioactive forms. In metal-exposed subjects, a state of latent Se deficiency may exist, resulting in depressed immune functions and increased cancer susceptibility. Evidence is presented to show that Pb and other metals also interact with iodine, another vitally important essential trace element believed to protect against breast cancer development. Public health programs aiming at lowering the breast cancer risk of Nigerian women thus will have to include effective measures to protect the population from exposures to Pb and other industrial metals that are presently contaminating the environment and the water supplies.

A case-control study on seaweed consumption and the risk of breast cancer

Gim (Porphyra sp.) and miyeok (Undaria pinnatifida) are the seaweeds most consumed by Koreans. We investigated the association between the intake of gim and miyeok and the risk of breast cancer in a case-control study. Cases were 362 women aged 30-65 years old, who were histologically confirmed to have breast cancer. Controls visiting the same hospital were matched to cases according to their age (sd 2 years) and menopausal status. Food intake was estimated by the quantitative FFQ with 121 items, including gim and miyeok. Conditional logistic regression analysis was used to obtain the OR and corresponding 95 % CI. The average intake and consumption frequency of gim in cases were lower than in controls. The daily intake of gim was inversely associated with the risk of breast cancer (5th v. 1st quintile, OR, 0.48; 95 % CI, 0.27, 0.86; P for trend, 0.026) after adjustment for potential confounders. After stratification analysis was performed according to menopausal status, premenopausal women (5th v. 1st quintile, OR, 0.44; 95 % CI, 0.24, 0.80; P for trend, 0.007) and postmenopausal women (5th v. 1st quintile, OR, 0.32; 95 % CI, 0.13, 0.80; P for trend, 0.06) showed similar inverse associations between gim intake and the risk of breast cancer after an adjustment for potential confounders except dietary factors. Miyeok consumption did not have any significant associations with breast cancer. These results suggest that high intake of gim may decrease the risk of breast cancer.

Iodine alters gene expression in the MCF7 breast cancer cell line: evidence for an anti-estrogen effect of iodine

The protective effects of iodine on breast cancer have been postulated from epidemiologic evidence and described in animal models. The molecular mechanisms responsible have not been identified but laboratory evidence suggests that iodine may inhibit cancer promotion through modulation of the estrogen pathway. To elucidate the role of iodine in breast cancer, the effect of Lugol's iodine solution (5% I(2), 10% KI) on gene expression was analyzed in the estrogen responsive MCF-7 breast cancer cell line. Microarray analysis identified 29 genes that were up-regulated and 14 genes that were down-regulated in response to iodine/iodide treatment. The altered genes included several involved in hormone metabolism as well as genes involved in the regulation of cell cycle progression, growth and differentiation. Quantitative RT-PCR confirmed the array data demonstrating that iodine/iodide treatment increased the mRNA levels of several genes involved in estrogen metabolism (CYP1A1, CYP1B1, and AKR1C1) while decreasing the levels of the estrogen responsive genes TFF1 and WISP2. This report presents the results of the first gene array profiling of the response of a breast cancer cell line to iodine treatment. In addition to elucidating our understanding of the effects of iodine/iodide on breast cancer, this work suggests that iodine/iodide may be useful as an adjuvant therapy in the pharmacologic manipulation of the estrogen pathway in women with breast cancer.

Uptake and gene expression with antitumoral doses of iodine in thyroid and mammary gland: evidence that chronic administration has no harmful effects

Several studies have demonstrated that moderately high concentrations of molecular iodine (I(2)) diminish the symptoms of mammary fibrosis in women, reduce the occurrence of mammary cancer induced chemically in rats (50-70%), and have a clear antiproliferative and apoptotic effect in the human tumoral mammary cell line MCF-7. Nevertheless, the importance of these effects has been underestimated, in part because of the notion that exposure to excess iodine represents a potential risk to thyroid physiology. In the present work we demonstrate that uptake and metabolism of iodine differ in an organ-specific manner and also depend on the chemical form of the iodine ingested (potassium iodide vs. I(2)). Further, we show that a moderately high I(2) supplement (0.05%) causes some of the characteristics of the "acute Wolff-Chaikoff effect"; namely, it lowers expression of the sodium/iodide symporter, pendrin, thyroperoxidase (TPO), and deiodinase type 1 in thyroid gland without diminishing circulating levels of thyroid hormone. Finally, we confirm that I(2) metabolism is independent of TPO, and we demonstrate that, at the doses used here, which are potentially useful to treat mammary tumors, chronic I(2) supplement is not accompanied by any harmful secondary effects on the thyroid or general physiology. Thus, we suggest that I(2) could be considered for use in clinical trials of breast cancer therapies.

A Prospective Study of Iodine Status, Thyroid Function, and Prostate Cancer Risk: Follow-up of the First National Health and Nutrition Examination Survey

Few studies have investigated the association between iodine status, thyroid disease, and cancer risk despite evidence that thyroid function impacts many organs, including the prostate. We investigated iodine status and prostate cancer risk prospectively using data from the NHANES I Epidemiologic Follow-up Study. Participants were stratified into tertiles according to the urinary iodine/creatinine ratio, as a marker of iodine exposure. As iodine is an integral constituent of thyroid hormones, we also examined the relationship between thyroid disease and prostate cancer risk. Relative to the group with low urinary iodine, the age-adjusted hazard ratio was higher (although marginally insignificant) in the moderate group, hazard ratio 1.33 (95% confidence interval 1.00-1.78), and significantly lower in the high group, 0.71 (0.51-0.99). Thyroid disease was associated with an increased prostate cancer risk, 2.34 (1.24-4.43). Similarly, > 10 yr since thyroid disease diagnosis was associated with an elevated risk, 3.38 (1.66-6.87). After adjusting for other confounding factors, only a history of thyroid disease, 2.16 (1.13-4.14), and > 10 yr since diagnosis of thyroid disease, 3.17 (1.54-6.51) remained significant. Although the role of dietary iodine remains speculative, a role for thyroid disease and/or factors contributing to thyroid disease as a risk factor for prostate carcinogenesis warrants additional investigation.

Enhanced tight junction function in human breast cancer cells by antioxidant, selenium and polyunsaturated lipid

Paracellular permeability (PCP) is governed by tight junctions (TJs) in epithelial cells, acting as cell-cell adhesion structures, the aberration of which is known to be linked to the dissociation and metastasis of breast cancer cells. This study hypothesized that the function of TJs in human breast cancer cells can be augmented by gamma linolenic acid (GLA), selenium (Se), and iodine (I) in the presence of 17-beta-estradiol, as these molecules are known to increase TJ functions in endothelial cells, using assays of trans-epithelial resistance (TER), PCP, immunofluorescence, and in vitro invasion and motility models. GLA, I, and Se individually increased TER of MDA-MB-231 and MCF-7 human breast cancer cells. The combination of all three agents also had a significant increase in TER. Addition of GLA/Se/I reduced PCP of both breast cancer cell lines. GLA/Se/I reversed the effect of 17-beta-estradiol (reduced TER, increased PCP). Immunofluorescence revealed that after treatment with Se/I/GLA over 24 h, there was increasing relocation to breast cancer cell-cell junctions of occludin and ZO-1 in MCF-7 cells. Moreover, treatment with GLA/Se/I, alone or in combination, significantly reduced in vitro invasion of MDA-MB-231 cells through an endothelial cell barrier (P < 0.0001) and reduced 17-beta-estradiol induced breast cancer cell motility (P < 0.0001). Our previous work has demonstrated that GLA, I, and Se alone, or in combination are able to strengthen the function of TJs in human endothelial cells; this has now proved to be true of human breast cancer cells. This combination also completely reversed the effect of 17-beta-estradiol in these cells.

Effect of an Anionic Surfactant on the Complexation of Some Nonionic Polymers with Iodine in Aqueous Media

Complexation of some water soluble nonionic polymers, namely, polyvinylalcohol (PVA), polyvinylpyrrolidone (PVP), and hydroxypropyl cellulose (HPC), with iodine has been studied in aqueous and aqueous sodiumdodecylsulfate (SDS) solution. While the complexation was indicated by a red shift of the tri-iodide band in case of PVP or HPC, the PVA-iodine complex showed its characteristic band around 500 nm. It was observed for the first time that presence of SDS led to complete break down of the PVA-iodine complex and its characteristic blue color. The presence of monomers of SDS, however, appeared to favor the formation of the iodine complex with PVP or HPC. Addition of n-propanol, which is known to prevent the formation of gels or microgels in polymer solutions, was found to enhance the polymer-iodine complex. Gels of pure HPC and HPC with iodine both in presence and absence of SDS have been prepared and studied.

Aqueous iodine equilibria in Mammalian iodination reactions

Regulatory activity has been demonstrated in two classes of iodinated organic species: thyroid hormones (T(3) and T(4)) and iodinated lipids (ILs), e.g. 6-iodo-5-hydroxy-8,11,14-eicosatrienoic acid. The formation of iodinated biomolecules requires iodide oxidation. In mammals iodide oxidation is one of several peroxidase-mediated reactions that serve to reduce hydrogen peroxide. I(2) is one of several reaction products formed by mammalian peroxidases during iodide oxidation. I(2) forms HOI in an aqueous environment which also has the capacity to iodinate organic species. This manuscript examines the potential relationship between the two classes of known mammalian iodinating species. A model describing iodination pathways for organic species in mammals is advanced. The model predicts the formation of ILs under normal dietary intake of iodine. The model was challenged by characterizing the lipids of hogs maintained on a diet containing normal levels of iodine. Iodinated lipids were found to be present in the fatty acids extracted from the thyroid of these hogs.

Lack of enhancement of susceptibility to mammary and thyroid carcinogenesis in rats exposed to DMBA and DHPN following prepubertal iodine deficiency

Epidemiologic and experimental studies suggest that iodine deficiency increases the risk of mammary as well as thyroid cancers, but susceptibility to tumor development when this occurs during the prepubertal stage is not completely understood. In the present study, we therefore evaluated this question in F344 rats. Dams during the lactation period and their weaned offspring until postnatal week 7 were fed an iodine-free diet. Female offspring were then given 7,12-dimethylbenz[a]anthracene (DMBA, 50 mg/kg body weight) by gavage for mammary tumor induction in week 7. Both the male and female rats were given free access to drinking water containing N-bis(2-hydroxypropyl)nitrosamine (DHPN), (0.1 and 0.2% for male and female rats, respectively) for wide spectrum tumor induction in organs, including the thyroid gland, from weeks 7-11. All offspring were killed at week 50 for histopathological examination. The iodine deficiency had no significant influence on incidences and/or multiplicities of mammary and thyroid tumors. Furthermore, tumor induction in the liver, kidney, lung, esophagus and urinary bladder was not affected in either sex. The present results thus indicate a lack of influence of iodine deficiency condition early in life on subsequent carcinogenic susceptibility.

Molecular iodine induces caspase-independent apoptosis in human breast carcinoma cells involving the mitochondria-mediated pathway

Molecular iodine (I2) is known to inhibit the induction and promotion of N-methyl-n-nitrosourea-induced mammary carcinogenesis, to regress 7,12-dimethylbenz(a)anthracene-induced breast tumors in rat, and has also been shown to have beneficial effects in fibrocystic human breast disease. Cytotoxicity of iodine on cultured human breast cancer cell lines, namely MCF-7, MDA-MB-231, MDA-MB-453, ZR-75-1, and T-47D, is reported in this communication. Iodine induced apoptosis in all of the cell lines tested, except MDA-MB-231, shown by sub-G1 peak analysis using flow cytometry. Iodine inhibited proliferation of normal human peripheral blood mononuclear cells; however, it did not induce apoptosis in these cells. The iodine-induced apoptotic mechanism was studied in MCF-7 cells. DNA fragmentation analysis confirmed internucleosomal DNA degradation. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling established that iodine induced apoptosis in a time- and dose-dependent manner in MCF-7 cells. Iodine-induced apoptosis was independent of caspases. Iodine dissipated mitochondrial membrane potential, exhibited antioxidant activity, and caused depletion in total cellular thiol content. Western blot results showed a decrease in Bcl-2 and up-regulation of Bax. Immunofluorescence studies confirmed the activation and mitochondrial membrane localization of Bax. Ectopic Bcl-2 overexpression did not rescue iodine-induced cell death. Iodine treatment induces the translocation of apoptosis-inducing factor from mitochondria to the nucleus, and treatment of N-acetyl-L-cysteine prior to iodine exposure restored basal thiol content, ROS levels, and completely inhibited nuclear translocation of apoptosis-inducing factor and subsequently cell death, indicating that thiol depletion may play an important role in iodine-induced cell death. These results demonstrate that iodine treatment activates a caspase-independent and mitochondria-mediated apoptotic pathway.

Synergistic regulation of endothelial tight junctions by antioxidant (Se) and polyunsaturated lipid (GLA) via Claudin-5 modulation

Tight junctions (TJs) in endothelial cells act as cell-cell adhesion structures, governing paracellular permeability (PCP). Disruption can lead to leaky vascular bed and potentially to oedema and swelling of tissues, the aetiology of mastalgia. These changes may also cause vascular spread of cancer cells. This study aimed to determine whether the function of TJs in endothelial cells can be strengthened by gamma linolenic acid (GLA), selenium (Se) and iodine (I) in the presence of 17beta-estradiol (17beta-estradiol), which causes leakage of endothelial cells by disruption of TJs in endothelium. GLA, I, and Se individually increased transendothelial resistance. The combination of all three agents also had a significant effect on TER. Addition of GLA/Se/I reduced PCP of the endothelial cells. Treatment with GLA/Se/I reversed the effect of 17beta-estradiol in reducing TER and increasing PCP. Immunofluorescence revealed that after treatment with Se/I/GLA over 24 h there was increasing relocation to endothelial cell-cell junctions of the TJ proteins Claudin-5, Occludin, and ZO-1. Interestingly, this relocation was particularly evident with treatments containing I when probing with Claudin-5 and those containing Se for Occludin. There was a small increase in overall protein levels when examined by Western blotting after treatment with GLA/Se/I when probed with Claudin-5 and Occludin. We report that GLA, I, and Se alone, or in combination are able to strengthen the function of TJs in human endothelial cells, by way of regulating the distribution of Claudin-5, Occludin, and ZO-1. Interestingly, this combination was also able to completely reverse the effect of 17beta-estradiol in these cells.

Inhibition of N-methyl-N-nitrosourea-induced mammary carcinogenesis by molecular iodine (I2) but not by iodide (I-) treatment Evidence that I2 prevents cancer promotion

We analyzed the effect of molecular iodine (I2), potassium iodide (KI) and a subclinical concentration of thyroxine (T4) on the induction and promotion of mammary cancer induced by N-methyl-N-nitrosourea. Virgin Sprague-Dawley rats received short or continuous treatment. Continuous I2 treated rats exhibited a strong and persistent reduction in mammary cancer incidence (30%) compared to controls (72.7%). Interruption of short or long term treatments resulted in a higher incidence in mammary cancer compared to the control groups. The protective effect of I2 was correlated with the highest expression of the I-/Cl- transporter pendrin and with the lowest levels of lipoperoxidation expression in mammary glands. Triiodothyronine serum levels and Na+/I- symporter, lactoperoxidase, or p53 expression did not show any changes. In conclusion continuous I2 treatment has a potent antineoplastic effect on the progression of mammary cancer and its effect may be related to a decrease in the oxidative cell environment.

Is iodine a gatekeeper of the integrity of the mammary gland?

This paper reviews evidence showing iodine as an antioxidant and antiproliferative agent contributing to the integrity of normal mammary gland. Seaweed is an important dietary component in Asian communities and a rich source of iodine in several chemical forms. The high consumption of this element (25 times more than in Occident) has been associated with the low incidence of benign and cancer breast disease in Japanese women. In animal and human studies, molecular iodine (I(2)) supplementation exerts a suppressive effect on the development and size of both benign and cancer neoplasias. This effect is accompanied by a significant reduction in cellular lipoperoxidation. Iodine, in addition to its incorporation into thyroid hormones, is bound into antiproliferative iodolipids in the thyroid called iodolactones, which may also play a role in the proliferative control of mammary gland. We propose that an I(2) supplement should be considered as an adjuvant in breast cancer therapy.

The effect of supraphysiologic levels of iodine on patients with cyclic mastalgia

A randomized, double-blind, placebo-controlled, multicenter clinical trial was conducted with 111 otherwise healthy euthyroid women with a history of breast pain. Patients had to document moderate or severe breast pain by recording a score > or =5 on a visual analog scale (VAS) of pain for > or =6 days per cycle and had to present with fibrosis involving at least 25% of both breast surfaces. Subjects could not be effectively treated with more conservative measures such as local heat or nonprescription analgesics. There was not a statistically significant difference in the dropout rate for patients on placebo (11.8%), 1.5 mg/day (31.3%), 3.0 mg/day (18.4%), or 6.0 mg/day (25%) of molecular iodine for 6 months. Physicians assessed breast pain, tenderness, and nodularity each cycle; patients assessed breast pain and tenderness with the Lewin breast pain scale at 3-month intervals and with a VAS at each cycle. A statistically significant improvement (p < 0.01) associated with dose was observed in the Lewin overall pain scale for all treated groups compared to placebo. Reductions in all three physician assessments were observed in patients after 5 months of therapy in the 3.0 mg/day (7/28; 25%) and 6.0 mg/day (15/27; 18.5%) treatment groups, but not the 1.5 mg/day or placebo group. Patients recorded statistically significant decreases in pain by month 3 in the 3.0 and 6.0 mg/day treatment groups, but not the 1.5 mg/day or placebo group; more than 50% of the 6.0 mg/day treatment group recorded a clinically significant reduction in overall pain. All doses were associated with an acceptable safety profile. No dose-related increase in any adverse event was observed.

The thyroid, iodine and breast cancer

A renewal of the search for a link between breast cancer and thyroid disease has once again demonstrated an increased prevalence of autoimmune thyroid disease in patients with breast cancer. This is the most recent of many studies showing an association between a variety of thyroid disorders and breast cancer. Such an association is not surprising as both diseases are female predominant with a similar postmenopausal peak incidence. The significance of the presence of thyroid autoantibodies, particularly thyroid peroxidase antibodies, in serum from patients with breast cancer is unknown, but it has been suggested that antibody positivity is associated with better prognosis. One area in which thyroid and breast functions overlap is in the uptake and utilization of dietary iodide. Experimental findings showing the ability of iodine or iodine-rich seaweed to inhibit breast tumour development is supported by the relatively low rate of breast cancer in Japanese women who consume a diet containing iodine-rich seaweed. However, there is as yet no direct evidence that iodine, iodinated compounds, or a combination of iodine and selenium is the antimammary carcinogenic element in the Japanese diet. It remains to be resolved whether the perceived breast cancer-thyroid disease relationship is thyroid or iodine related or, in the case of thyroid autoantibodies, is the consequence of an immune response to the carcinoma. Is this response breast specific and does it relate to iodine status? These and many other questions await resolution before a definitive role in the natural history of breast carcinoma can be assigned to the thyroid.

Role of iodine in antioxidant defence in thyroid and breast disease

The role played in thyroid hormonogenesis by iodide oxidation to iodine (organification) is well established. Iodine deficiency may produce conditions of oxidative stress with high TSH producing a level of H_2O_2, which because of lack of iodide is not being used to form thyroid hormones. The cytotoxic actions of excess iodide in thyroid cells may depend on the formation of free radicals and can be attributed to both necrotic and apoptotic mechanisms with necrosis predominating in goiter development and apoptosis during iodide induced involution. These cytotoxic effects appear to depend on the status of antioxidative enzymes and may only be evident in conditions of selenium deficiency where the activity of selenium containing antioxidative enzymes is impaired. Less compelling evidence exists of a role for iodide as an antioxidant in the breast. However the Japanese experience may indicate a protective effect against breast cancer for an iodine rich seaweed containing diet. Similarly thyroid autoimmunity may also be associated with improved prognosis. Whether this phenomenon is breast specific and its possible relationship to iodine or selenium status awaits resolution.

Iodine nutrition and breast feeding

A survey of the databanks Medline and Web of science identified studies dealing with maternal and infant iodine nutrition during breast feeding. The iodine concentration of human milk varies widely due to maternal iodine intake. Mean breast milk iodine concentrations are reported as ranging from 5.4 to 2170 microg/L (median 62 microg/L) in worldwide studies. In the few studies that compared length of lactation, gestation length, and parity number, these factors did not significantly affect milk-iodine concentrations. In studies of maternal iodine deficiency, untreated goiter had no impact on breast milk iodine when compared with controls. Iodine in human milk responds quickly to dietary iodine intake, either supplemented or consumed in natural foods. Easily absorbable iodine from foods, supplemental sources, iodine-based medication or iodine-based antiseptic solutions used during parturition, is taken up by the maternal thyroid and mammary glands through the Na(+)/I(-) symporter system. This transmembrane carrier protein transports iodine against a high concentration gradient. Hormonal iodine in breast milk occurs mainly as T-4, but depending on maternal iodine intake, high concentrations of the inorganic form (iodide) are found. In less developed countries, where natural-food-iodine intake is low, adequate maternal iodine nutritional status depends exclusively on enforcement of food iodination. In industrialized countries, maternal iodine intake has increased as a function of increasing consumption of dairy products. The human infant is sensitive to maternal iodine nutrition during fetal development and later during breast feeding. Environmental factors, not directly related to maternal iodine intake, such as intake of selenium and organochlorine pollutants, can affect thyroid hormone homeostasis in breast-fed infants. In spite of low iodine concentrations found in milk of mothers consuming low-iodine natural foods, long lasting or even life-lasting benefits to the breast-fed infant are demonstrable.

Seaweed prevents breast cancer?

To investigate the chemopreventive effects of seaweed on breast cancer, we have been studying the relationship between iodine and breast cancer. We found earlier that the seaweed, wakame, showed a suppressive effect on the proliferation of DMBA (dimethylbenz(a)anthracene)‐induced rat mammary tumors, possibly via apoptosis induction. In the present study, powdered mekabu was placed in distilled water, and left to stand for 24 h at 4°C. The filtered supernatant was used as mekabu solution. It showed an extremely strong suppressive effect on rat mammary carcinogenesis when used in daily drinking water, without toxicity. In vitro, mekabu solution strongly induced apoptosis in 3 kinds of human breast cancer cells. These effects were stronger than those of a chemothera‐peutic agent widely used to treat human breast cancer. Furthermore, no apoptosis induction was observed in normal human mammary cells. In Japan, mekabu is widely consumed as a safe, inexpensive food. Our results suggest that mekabu has potential for chemoprevention of human breast

Iodine and cancer

Thyroid carcinomas are the most frequent endocrine malignancies. Among thyroid carcinomas the most frequent types are the differentiated forms (follicular, papillary or mixed papillary-follicular), whereas anaplastic thyroid carcinoma and medullary thyroid carcinomas are rare. Animal experiments have demonstrated a clear increase in incidence of thyroid epithelial cell carcinomas after prolonged iodine deficiency leading to a situation of the thyroid gland by thyrotropin and possibly other growth factors. However, the overall incidence of differentiated thyroid carcinoma is generally not considered to be influenced by the iodine intake of a population, whereas the distribution of the types of thyroid carcinoma seems to be related to the intake of iodine, with fewer of the more aggressive follicular and anaplastic carcinomas and more papillary carcinomas in iodine rich areas. Populations starting iodine prophylaxis demonstrate an increase in the ratio of papillary to follicular carcinoma. Because a population with higher iodine intake usually has fewer benign nodules in the thyroid gland and the incidence of thyroid carcinomas is similar to an iodine-deficient region, the diagnostic work-up of nodules in the thyroid gland may become affected. The incidence of other cancers, such as breast cancer, may be influenced by the iodine intake, but too few studies are available at present. The present article summarizes available data from both epidemiological studies, animal experiments, and basic gene transfection studies. The overall incidence for a relationship between iodine and cancer is poor and future studies are warranted.

Tissue iodine content and serum-mediated 125I uptake-blocking activity in breast cancer

In the thyroid, active transport of iodide is under control of the TSH-dependent Na+/I- symporter (NIS), whereas in the breast such control is less well understood. In this study, NIS expression was demonstrated by RT-PCR in 2 of 2 fibroadenomata and 6 of 7 breast carcinoma messenger ribonucleic acid isolates. In addition, mean total tissue iodine levels of 80.9 +/- 9.5 ng I/mg protein in 23 benign tumors (fibroadenomata) were significantly higher than those in 19 breast cancers taken from either the tumor (18.2 +/- 4.6 ng I/mg) or morphologically normal tissue taken from within the tumor-bearing breast (31.8 +/- 4.9 ng I/mg; P < 0.05 in each case). Inhibition of 125I uptake into NIS-transfected CHO cells was observed in serum from 20 of 105 (19.0%) breast carcinoma, 8 of 49 (16.3%) benign breast disease, and 27 of 86 (31.4%) Graves' patients, but in only 1 of 33 (3.0%) age-matched female controls. IgG purified from serum of patients showing positive 125I uptake inhibition also inhibited iodide uptake, suggesting that such inhibition was antibody mediated. 125I uptake inhibition was significantly associated with thyroid peroxidase antibody positivity (P < 0.05) in sera from breast cancer patients, but not in those with benign breast disease, once again suggesting an association between thyroid autoimmunity and breast carcinoma.

Wakame seaweed suppresses the proliferation of 7,12-dimethylbenz(a)-anthracene-induced mammary tumors in rats

We examined the anti-tumor proliferation effects of wakame seaweed on 7,12-dimethylbenz(a)-anthracene (DMBA)-induced rat mammary tumor. DMBA was administered to 8-week-old female Sprague-Dawley rats, and rats which developed mammary tumors were assigned randomly to three groups. Commercial rat feed was used in a control group (group I-A), and two feed mixtures were prepared, which contained commercial rat feed blended with wakame at 1.0% (group I-B) and 5.0% (group I-C) by weight. The respective feeds were given to each group for 8 weeks, and changes in mammary tumor size were compared. At the end of the experiment, mammary tumors and thyroid glands were resected to compare their weights. Serum total iodine and thyroxin (T4) levels were measured. Immunohistochemical studies for bromodeoxyuridine (BrdU) labeling, transforming growth factor (TGF)-beta, and apoptosis were carried out in the resected tumor. Significant suppression of tumor growth was observed in groups I-B and I-C compared with I-A. In groups I-B and I-C, the weights of resected mammary tumors were significantly lower and serum total iodine concentration was significantly higher than in I-A. BrdU indices were significantly lower in groups I-B and I-C, compared with I-A. TGF-beta and apoptotic index were inversely related to BrdU. These results suggest that iodine is transported from the serum into mammary tissues and induces apoptosis through the expression of TGF-beta. In conclusion, wakame suppressed the proliferation of DMBA-induced mammary tumors.