Accuracy and Precision of Iodine Quantification in Subtracted Micro-Computed Tomography: Effect of Reconstruction and Noise Removal Algorithms

PURPOSE

To evaluate the effect of reconstruction and noise removal algorithms on the accuracy and precision of iodine concentration (CI) quantified with subtracted micro-computed tomography (micro-CT).

PROCEDURES

Two reconstruction algorithms were evaluated: a filtered backprojection (FBP) algorithm and a simultaneous iterative reconstruction technique (SIRT) algorithm. A 3D bilateral filter (BF) was used for noise removal. A phantom study evaluated and compared the image quality, and the accuracy and precision of CI in four scenarios: filtered FBP, filtered SIRT, non-filtered FBP, and non-filtered SIRT. In vivo experiments were performed in an animal model of chemically-induced mammary cancer.

RESULTS

Linear relationships between the measured and nominal CI values were found for all the scenarios in the phantom study (R2 > 0.95). SIRT significantly improved the accuracy and precision of CI compared to FBP, as given by their lower bias (adj. p-value = 0.0308) and repeatability coefficient (adj. p-value < 0.0001). Noise removal enabled a significant decrease in bias in filtered SIRT images only; non-significant differences were found for the repeatability coefficient. The phantom and in vivo studies showed that CI is a reproducible imaging parameter for all the scenarios (Pearson r > 0.99, p-value < 0.001). The contrast-to-noise ratio showed non-significant differences among the evaluated scenarios in the phantom study, while a significant improvement was found in the in vivo study when SIRT and BF algorithms were used.

CONCLUSIONS

SIRT and BF algorithms improved the accuracy and precision of CI compared to FBP and non-filtered images, which encourages their use in subtracted micro-CT imaging.

Preventive Effect of Molecular Iodine in Pancreatic Disorders from Hypothyroid Rabbits

Pancreatic alterations such as inflammation and insulin resistance accompany hypothyroidism. Molecular iodine (I2) exerts antioxidant and differentiation actions in several tissues, and the pancreas is an iodine-uptake tissue. We analyzed the effect of two oral I2 doses on pancreatic disorders in a model of hypothyroidism for 30 days. Adult female rabbits were divided into the following groups: control, moderate oral dose of I2 (0.2 mg/kg, M-I2), high oral dose of I2 (2.0 mg/kg, H-I2), oral dose of methimazole (MMI; 10 mg/kg), MMI + M-I2,, and MMI + H-I2. Moderate or high I2 supplementation did not modify circulating metabolites or pancreatic morphology. The MMI group showed reductions of circulating thyroxine (T4) and triiodothyronine (T3), moderate glucose increments, and significant increases in cholesterol and low-density lipoproteins. Acinar fibrosis, high insulin content, lipoperoxidation, and overexpression of GLUT4 were observed in the pancreas of this group. M-I2 supplementation normalized the T4 and cholesterol, but T3 remained low. Pancreatic alterations were prevented, and nuclear factor erythroid-2-related factor-2 (Nrf2), antioxidant enzymes, and peroxisome proliferator-activated receptor gamma (PPARG) maintained their basal values. In MMI + H-I2, hypothyroidism was avoided, but pancreatic alterations and low PPARG expression remained. In conclusion, M-I2 supplementation reestablishes thyronine synthesis and diminishes pancreatic alterations, possibly related to Nrf2 and PPARG activation.

Protective effects of iodine on rat prostate inflammation induced by sex hormones and on the DU145 prostate cancer cell line treated with TNF

Molecular iodine (I₂) prevents oxidative stress and prostate hyperplasia induced by hyperandrogenism and reduces cell viability in prostate cancer cell lines. Here, we aimed to evaluate the protective effect of I₂ and testosterone (T) on hyperestrogenism-induced prostate inflammation. Additionally, the effects of I₂ and/or tumor necrosis factor (TNF) on cell viability and interleukin 6 (IL6) secretion were evaluated in a prostate cancer cell line (DU145). We also investigated whether the effects of I₂ on viability are peroxisome proliferator-activated receptor gamma (PPARG)-dependent. Castrated (Cx) rats received pellets of either 17β estradiol (E₂) or E₂ and T and were treated with I₂ (0.05%) in the drinking water for four weeks. The experimental groups were sham, Cx, Cx + E₂, Cx + E₂+I₂, Cx + E₂+T, and Cx + E₂+T + I₂. As expected, inflammation was triggered in the Cx + E₂ group (high inflammation score; increase in TNF and transcriptional activity of RELA [nuclear factor-kappa B p65 subunit]), and this effect was diminished in the Cx + E₂+T group (medium inflammation score and decrease in TNF). The lowest inflammation score (decrease of TNF and RELA and increase of PPARG) was obtained in the Cx + E₂+T + I₂ group. In DU145 cells, I₂ (400 μM) and TNF (10 ng/ml) additively reduced cell viability, and I₂ reduced the production of TNF-stimulated IL6. The PPARG antagonist (GW9662) did not inhibit the effects of I₂ on the loss of cell viability. In summary, our data suggest that I₂ and T exert a synergistic anti-inflammatory action on the normal prostate, and the interrelationship between I₂ and TNF leads to anti-proliferative effects in DU145 cells. PPARG does not seem to participate in the I₂-induced cell viability loss in the prostate.

Neuroendocrine Differentiation of Lung Cancer Cells Impairs the Activation of Antitumor Cytotoxic Responses in Mice

Lung cancer has the highest mortality among all types of cancer; during its development, cells can acquire neural and endocrine properties that affect tumor progression by releasing several factors, some acting as immunomodulators. Neuroendocrine phenotype correlates with invasiveness, metastasis, and low survival rates. This work evaluated the effect of neuroendocrine differentiation of adenocarcinoma on the mouse immune system. A549 cells were treated with FSK (forskolin) and IBMX (3-Isobutyl-1-methylxanthine) for 96 h to induce neuroendocrine differentiation (NED). Systemic effects were assessed by determining changes in circulating cytokines and immune cells of BALB/c mice immunized with PBS, undifferentiated A549 cells, or neuroendocrine A549_NED cells. A549 cells increased circulating monocytes, while CD4⁺CD8^- and CD4⁺CD8⁺ T cells increased in mice immunized with neuroendocrine cells. IL-2 and IL-10 increased in mice that received untreated A549 cells, suggesting that the immune system mounts a regulated response against adenocarcinoma, which did not occur with A549_NED cells. Cocultures demonstrated the cytotoxic capacity of PBMCs when confronted with A549 cells, while in the presence of neuroendocrine cells they not only were unable to show cytolytic activity, but also lost viability. Neuroendocrine differentiation seems to mount less of an immune response when injected in mice, which may contribute to the poor prognosis of cancer patients affected by this pathology.

Effects of hypothyroidism on the female pancreas involve the regulation of estrogen receptors

This study aimed to investigate the impact of short-time hypothyroidism on the expression of aromatase, estrogen receptors (ERα, β), and GPR30 in the pancreas of female rabbits. The formation of new islets and the expression of insulin, GLUT4, and lactate dehydrogenase (LDH) were also analyzed. This purpose is based on actions that thyroid hormones and estrogens have on β-cells differentiation, acinar cell function, and insulin secretion. Twelve Chinchilla-breed adult virgin female rabbits were divided into control (n = 6) and hypothyroid (n = 6; methimazole 10 mg/kg for 30 days) groups. In the complete pancreas, expressions of aromatase and estrogen receptors, as well as proinsulin, GLUT4, and LDH were determined by western blot. Characteristics of islets were measured in slices of the pancreas with immunohistochemistry for insulin. Islet and acinar cells express aromatase, ERα, ERβ, and GPR30. Hypothyroidism increased the expression of ERα and diminished that for aromatase, ERβ, and GPR30 in the pancreas. It also promoted a high number of extra small islets (new islets) and increased the expression of proinsulin and GLUT4 in the pancreas. Our results show that actions of thyroid hormones and estrogens on β-cells neogenesis, acinar cell function, and synthesis and secretion of insulin are linked. Thus, the effects of hypothyroidism on the pancreas could include summatory actions of thyroid hormones plus estrogens. Our findings indicate the importance of monitoring estrogen levels and actions on the pancreas of hypothyroid women, particularly when serum estrogen concentrations are affected such as menopausal, pregnant, and those with contraceptive use.

Prostate gland as a target organ of thyroid hormones: advances and controversies

Thyroid hormones (THs) are involved in the development and function of the male reproductive system, but their effects on the prostate have been poorly studied. This work reviews studies related to the interrelationship between the thyroid and the prostate. The information presented here is based upon bibliographic searches in PubMed using the following search terms: prostate combined with thyroid hormone or triiodothyronine, thyroxine, hypothyroidism, hyperthyroidism, or deiodinase. We identified and searched 49 articles directly related to the issue, and discarded studies related to endocrine disruptors. The number of publications has grown in the last 20 years, considering that one of the first studies was published in 1965. This review provides information based on in vitro studies, murine models, and clinical protocols in patients with thyroid disorders. Studies indicate that THs regulate different aspects of growth, metabolism, and prostate pathology, whose global effect depends on total and/or free concentrations of THs in serum, local bioavailability, and the endocrine androgen/thyronine context.

Molecular Iodine Supplement Prevents Streptozotocin-Induced Pancreatic Alterations in Mice

Pancreatitis has been implicated in the development and progression of type 2 diabetes and cancer. The pancreas uptakes molecular iodine (I₂), which has anti-inflammatory and antioxidant effects. The present work analyzes whether oral I₂ supplementation prevents the pancreatic alterations promoted by low doses of streptozotocin (STZ). CD1 mice (12 weeks old) were divided into the following groups: control; STZ (20 mg/kg/day, i.p. for five days); I₂ (0.2 mg/Kg/day in drinking water for 15 days); and combined (STZ + I₂). Inflammation (Masson’s trichrome and periodic acid–Schiff stain), hyperglycemia, decreased β-cells and increased α-cells in pancreas were observed in male and female animals with STZ. These animals also showed pancreatic increases in immune cells and inflammation markers as tumor necrosis factor-alpha, transforming growth factor-beta and inducible nitric oxide synthase with a higher amount of activated pancreatic stellate cells (PSCs). The I₂ supplement prevented the harmful effect of STZ, maintaining normal pancreatic morphometry and functions. The elevation of the nuclear factor erythroid-2 (Nrf2) and peroxisome proliferator-activated receptor type gamma (PPARγ) contents was associated with the preservation of normal glycemia and lipoperoxidation. In conclusion, a moderated supplement of I₂ prevents the deleterious effects of STZ in the pancreas, possibly through antioxidant and antifibrotic mechanisms including Nrf2 and PPARγ activation.

Effects of Molecular Iodine/Chemotherapy in the Immune Component of Breast Cancer Tumoral Microenvironment

Molecular iodine (I₂) induces apoptotic, antiangiogenic, and antiproliferative effects in breast cancer cells. Little is known about its effects on the tumor immune microenvironment. We studied the effect of oral (5 mg/day) I₂ supplementation alone (I₂) or together with conventional chemotherapy (Cht+I₂) on the immune component of breast cancer tumors from a previously published pilot study conducted in Mexico. RNA-seq, I₂ and Cht+I₂ samples showed significant increases in the expression of Th1 and Th17 pathways. Tumor immune composition determined by deconvolution analysis revealed significant increases in M0 macrophages and B lymphocytes in both I₂ groups. Real-time RT-PCR showed that I₂ tumors overexpress T-BET (p = 0.019) and interferon-gamma (IFNγ; p = 0.020) and silence tumor growth factor-beta (TGFβ; p = 0.049), whereas in Cht+I₂ tumors, GATA3 is silenced (p = 0.014). Preliminary methylation analysis shows that I₂ activates IFNγ gene promoter (by increasing its unmethylated form) and silences TGFβ in Cht+I₂. In conclusion, our data showed that I₂ supplements induce the activation of the immune response and that when combined with Cht, the Th1 pathways are stimulated. The molecular mechanisms involved in these responses are being analyzed, but preliminary data suggest that methylation/demethylation mechanisms could also participate.

A rise in T3/T4 ratio reduces the growth of prostate tumors in a murine model

Thyroxine (T4) promotes cell proliferation and tumor growth in prostate cancer models, but it is unknown if the increase in the triiodothyronine (T3)/T4 ratio could attenuate prostate tumor development. We assessed T3 effects on thyroid response, histology, proliferation, and apoptosis in the prostate of wild-type (WT) and TRAMP (transgenic adenocarcinoma of the mouse prostate) mice. Physiological doses of T3 were administered in the drinking water (2.5, 5 and 15 µg/100 g body weight) for 6 weeks. None of the doses modified the body weight or serum levels of testosterone, but all of them reduced serum T4 levels by 50%, and the highest dose increased the T3/T4 ratio in TRAMP. In WT, the highest dose of T3 decreased cyclin D1 levels (immunohistochemistry) but did not modify prostate weight or alter the epithelial morphology. In TRAMP, this dose reduced tumor growth by antiproliferative mechanisms independent of apoptosis, but it did not modify the intraluminal or fibromuscular invasion of tumors. In vitro, in the LNCaP prostate cancer cell line, we found that both T3 and T4 increased the number of viable cells (Trypan blue assay), and only T4 response was fully blocked in the presence of an integrin-binding inhibitor peptide (RGD, arginine-glycine-aspartate). In summary, our data show that the prostate was highly sensitive to physiological T3 doses and suggest that in vivo, an increase in the T3/T4 ratio could be associated with the reduced weight of prostate tumors. Longitudinal studies are required to understand the role of thyroid hormones in prostate cancer progression.

Molecular iodine synergized and sensitized neuroblastoma cells to the antineoplastic effect of ATRA

Neuroblastoma (NB) is the most common solid childhood tumor, and all-trans retinoic acid (ATRA) is used as a treatment to decrease minimal residual disease. Molecular iodine (I2) induces differentiation and/or apoptosis in several neoplastic cells through activation of PPARγ nuclear receptors. Here, we analyzed whether the coadministration of I2 and ATRA increases the efficacy of NB treatment. ATRA-sensitive (SH-SY5Y), partially-sensitive (SK-N-BE(2)), and non-sensitive (SK-N-AS) NB cells were used to analyze the effect of I2 and ATRA in vitro and in xenografts (Foxn1 nu/nu mice), exploring actions on cellular viability, differentiation, and molecular responses. In the SH-SY5Y cells, 200 μM I2 caused a 100-fold (0.01 µM) reduction in the antiproliferative dose of ATRA and promoted neurite extension and neural marker expression (tyrosine hydroxylase (TH) and tyrosine kinase receptor alpha (Trk-A)). In SK-N-AS, the I2 supplement sensitized these cells to 0.1 μM ATRA, increasing the ATRA-receptor (RARα) and PPARγ expression, and decreasing the Survivin expression. The I2 supplement increased the mitochondrial membrane potential in SK-N-AS suggesting the participation of mitochondrial-mediated mechanisms involved in the sensibilization to ATRA. In vivo, oral I2 supplementation (0.025%) synergized the antitumor effect of ATRA (1.5 mg/kg BW) and prevented side effects (body weight loss and diarrhea episodes). The immunohistochemical analysis showed that I2 supplementation decreased the intratumoral vasculature (CD34). We suggest that the I2 + ATRA combination should be studied in preclinical and clinical trials to evaluate its potential adjuvant effect in addition to conventional treatments.

Micronutrients and Breast Cancer Progression: A Systematic Review

Epidemiological studies on micronutrient consumption have reported protective associations in the incidence and/or progression of various cancer types. Supplementation with some of these micronutrients has been analyzed, showing chemoprotection, low toxicity, antiproliferation, and the ability to modify epigenetic signatures in various cancer models. This review investigates the reported effects of micronutrient intake or supplementation in breast cancer progression. A PubMed search was conducted with the keywords "micronutrients breast cancer progression", and the results were analyzed. The selected micronutrients were vitamins (C, D, and E), folic acid, metals (Cu, Fe, Se, and Zn), fatty acids, polyphenols, and iodine. The majority of in vitro models showed antiproliferative, cell-cycle arrest, and antimetastatic effects for almost all the micronutrients analyzed, but these effects do not reflect animal or human studies. Only one clinical trial with vitamin D and one pilot study with molecular iodine showed favorable overall survival and disease-free interval.

Shock Wave Application Increases the Antineoplastic Effect of Molecular Iodine Supplement in Breast Cancer Xenografts

We evaluated the effect of oral molecular iodine supplementation and shock wave application under three different conditions on human MDA-MB231 cancer cell xenografts. After tumor volume reached 1 cm³, mice were randomly assigned to groups and treated for 3 weeks. The results revealed that high-dose shock wave treatment (150 shock waves at a pressure of 21.7 MPa, SW150/21.7) generated tissue lesions without decreasing tumor growth, canceled the antineoplastic action of iodine and promoted pro-tumor conditions (increased hypoxia-induced factor [HIF] and vascular endothelial growth factor [VEGF]). In contrast, moderate (SW35/21.7) and low (SW35/9.9) doses of shock waves had significant antineoplastic effects and, in combination with iodine supplement, attenuated the aggressiveness of these cells by decreasing expression of the markers of stem cells (CD44 and Sox2) and invasion (HIF and VEGF). These results allow us to propose the combination of shock waves and iodine as a possible adjuvant in breast cancer therapy.

Adjuvant Effect of Molecular Iodine in Conventional Chemotherapy for Breast Cancer. Randomized Pilot Study

This study analyzes an oral supplement of molecular iodine (I₂), alone and in combination with the neoadjuvant therapy 5-fluorouracil/epirubicin/cyclophosphamide or taxotere/epirubicin (FEC/TE) in women with Early (stage II) and Advanced (stage III) breast cancer. In the Early group, 30 women were treated with I₂ (5 mg/day) or placebo (colored water) for 7–35 days before surgery. For the Advanced group, 30 patients received I₂ or placebo, along with FEC/TE treatment. After surgery, all patients received FEC/TE + I₂ for 170 days. I₂ supplementation showed a significant attenuation of the side effects and an absence of tumor chemoresistance. The control, I₂, FEC/TE, and FEC/TE + I₂ groups exhibited response rates of 0, 33%, 73%, and 100%, respectively, and a pathologic complete response of 18%, and 36% in the last two groups. Five-year disease-free survival rate was significantly higher in patients treated with the I₂ supplement before and after surgery compared to those receiving the supplement only after surgery (82% versus 46%). I₂-treated tumors exhibit less invasive potential, and significant increases in apoptosis, estrogen receptor expression, and immune cell infiltration. Transcriptomic analysis indicated activation of the antitumoral immune response. The results led us to register a phase III clinical trial to analyze chemotherapy + I₂ treatment for advanced breast cancer.

SAT-561 Protective Effect of Moderated Dose of Iodine in Pancreatic Alterations during Hypothyroidism

Pancreatitis and insulitis are known causes of type 2 diabetes mellitus, and recently it has been shown that hypothyroidism can exacerbate these alterations. Molecular iodine (I₂) exerts antioxidant, anti-inflammatory, and anti-dyslipidemia effects in diverse tissues. The objective of this study was to evaluate the effect of the oral supplement of this halogen in the induction of prediabetic status in a model of pharmacological hypothyroidism. Adult virgin rabbits of the Chinchilla breed were divided into control (n = 6) and hypothyroid (methimazole, MMI n = 6, 10 mg/kg in drinking water) groups, supplemented with moderate (MMI + I₂ 0.2 mg/kg; n= 6) and high dose of I₂ (MMI + I₂ 2 mg/kg, n= 6). The results showed that hypothyroidism (1 month) was accompanied by circulating elevations of total cholesterol, HDL, LDL (enzymatic methods) and sCD163 (Western blot). It also promoted pancreatitis (H & E, Masson's trichrome, and PAS stains, as well as western blot for CD163) and insulitis (PAS and Masson's trichrome stains). In the pancreas, hypothyroidism increased the beta-amyloid around vessels (Congo red stain); triglycerides (Folch method), lipoperoxidation (levels of malondialdehyde MDA, enzymatic method) and expression of insulin and GLUT4. A low cholesterol synthesis (Folch method and western blot for CYP51A1) and a decrease in the expression of PPARγ (immunohistochemistry and western blot) were also observed. High doses of I₂ supplement (2 mg/kg) aggravated pancreatic damage, promoting even islet amyloidosis and fibrosis. In contrast, the moderate dose of I₂ (0.2 mg / kg) was able to prevent alterations in circulating lipids and in the pancreatic tissue. This prevention was accompanied by a significant decrease in the lipoperoxidation and a great expression of PPARγ. These results describe for first time the anti-inflammatory and anti-dyslipidemia effect of the moderate dose of I₂ in the pancreas and suggest the possible participation of PPARγ receptors. More studies are needed to analyze the therapeutic effect of iodine in chronic pancreatic diseases associated with inflammation. This work was partially supported by grants CONACyT 257549 and PAPIIT-UNAM 201516.

Molecular iodine exerts antineoplastic effects by diminishing proliferation and invasive potential and activating the immune response in mammary cancer xenografts

Background

The immune system is a crucial component in cancer progression or regression. Molecular iodine (I₂) exerts significant antineoplastic effects, acting as a differentiation inductor and immune modulator, but its effects in antitumor immune response are not elucidated.

Methods

The present work analyzed the effect of I₂ in human breast cancer cell lines with low (MCF-7) and high (MDA-MB231) metastatic potential under both in vitro (cell proliferation and invasion assay) and in vivo (xenografts of athymic nude mice) conditions.

Results

In vitro analysis showed that the 200 μM I₂ supplement decreases the proliferation rate in both cell lines and diminishes the epithelial-mesenchymal transition (EMT) profile and the invasive capacity in MDA-MB231. In immunosuppressed mice, the I₂ supplement impairs implantation (incidence), tumoral growth, and proliferation of both types of cells. Xenografts of the animals treated with I₂ decrease the expression of invasion markers like CD44, vimentin, urokinase plasminogen activator and its receptor, and vascular endothelial growth factor; and increase peroxisome proliferator-activated receptor gamma. Moreover, in mice with xenografts, the I₂ supplement increases the circulating level of leukocytes and the number of intratumoral infiltrating lymphocytes, some of them activated as CD8+, suggesting the activation of antitumor immune responses.

Conclusions

I₂ decreases the invasive potential of a triple negative basal cancer cell line, and under in vivo conditions the oral supplement of this halogen activates the antitumor immune response, preventing progression of xenografts from laminal and basal mammary cancer cells. These effects allow us to propose iodine supplementation as a possible adjuvant in breast cancer therapy.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5437-3) contains supplementary material, which is available to authorized users.

Molecular iodine inhibits the expression of stemness markers on cancer stem-like cells of established cell lines derived from cervical cancer

BACKGROUND

Cancer stem cells (CSC) are characterized by deregulated self-renewal, tumorigenicity, metastatic potential, aberrant stemness signaling pathways, resistance to conventional therapy, and the ability to give rise to a progeny of proliferating cells that constitute the bulk of tumors. Targeting CSC will provide novel treatments for cancer. Different investigations have focused on developing complementary approaches that involve natural compounds that decrease chemo-resistance and reduce the side effects of conventional therapies. Since, it has been reported that molecular iodine (I₂) exhibits antineoplastic effects and decreases tumor progression in some cancer models, we evaluated the potential effect of I₂ on cell cultures enriched in cervical cancer stem-like cells.

METHODS

HeLa and SiHa cervical cancer cells were treated with 200uM I₂ for 24 h. After time, cells were cultured in CSC-conditioned medium (cervospheres) and viability assays were performed. Following, tumorigenic capabilities in cervospheres treated with I₂ were evaluated in NOD/SCID mice. HeLa monolayer cells untreated and their respective cervosphere cells treated or untreated with 200 μM of I₂ for 24 h were xenotransplanted subcutaneously at different amounts and mice were monitored for at least 2 months.

RESULTS

In the present study, monolayer and CSC-enriched cultures (cervospheres) from cervical cancer-derived cell lines, HeLa and SiHa, showed that 200uM I₂ supplementation inhibits proliferation of both and decreased their tumorigenic capacity, in vivo. This antineoplastic effect of I₂ was accompanied by diminished expression of stemness markers including CD49f, CK17, OCT-4, NANOG, SOX2, and KLF4, as well as increased expression and activation of PPARγ receptors.

CONCLUSIONS

All this data led us to suggest a clinical potential use of I₂ for targeting CSC and improve current treatments against cervical cancer.

Molecular iodine/doxorubicin neoadjuvant treatment impair invasive capacity and attenuate side effect in canine mammary cancer

Background

Mammary cancer has a high incidence in canines and is an excellent model of spontaneous carcinogenesis. Molecular iodine (I₂) exerts antineoplastic effects on different cancer cells activating re-differentiation pathways. In co-administration with anthracyclines, I₂ impairs chemoresistance installation and prevents the severity of side effects generated by these antineoplastic drugs. This study is a random and double-blind protocol that analyzes the impact of I₂ (10 mg/day) in two administration schemes of Doxorubicin (DOX; 30 mg/m2) in 27 canine patients with cancer of the mammary gland. The standard scheme (sDOX) includes four cycles of DOX administered intravenously for 20 min every 21 days, while the modified scheme (mDOX) consists of more frequent chemotherapy (four cycles every 15 days) with slow infusion (60 min). In both schemes, I₂ or placebo (colored water) was supplemented daily throughout the treatment.

Results

mDOX attenuated the severity of adverse events (VCOG-CTCAE) in comparison with the sDOX group. The overall tumor response rate (RECIST criteria) for all dogs was 18% (interval of reduction 48–125%), and no significant difference was found between groups. I₂ supplementation enhances the antineoplastic effect in mDOX, exhibiting a significant decrease in the tumor epithelial fraction, diminished expression of chemoresistance (MDR1 and Survivin) and invasion (uPA) markers and enhanced expression of the differentiation factor known as peroxisome proliferator-activated receptors type gamma (PPARγ). Significant tumor lymphocytic infiltration was also observed in both I₂-supplemented groups. The ten-month survival analysis showed that the entire I₂ supplementation (before and after surgery) induced 67–73% of disease-free survival, whereas supplementation in the last period (only after surgery) produced 50% in both schemes.

Conclusions

The mDOX+I₂ scheme improves the therapeutic outcome, diminishes the invasive capacity, attenuates the adverse events and increases disease-free survival. These data led us to propose mDOX+I₂ as an effective treatment for canine mammary cancer.

Iodine prevents the increase of testosterone-induced oxidative stress in a model of rat prostatic hyperplasia

Oxidative stress and inflammation are involved in the development and/or progression of benign prostatic hyperplasia (BPH). Molecular iodine (I₂) induces antiproliferative and apoptotic effects in prostate cancer cells, but it is unknown if I₂ regulates oxidative stress in the normal and/or tumoral prostate. The purpose of this study was to analyze the effects of I₂ and celecoxib (Cxb) on oxidative stress and inflammation in a model of prostatic hyperplasia. Cxb was used as positive control of cyclooxygenase-2 (COX-2) inhibition. Prostatic hyperplasia was induced in male Wistar rats (170g) with testosterone (5mg/kg/week, for three weeks). One week before hyperplasia induction, I₂ (25mg/day/rat) or Cxb (1.25mg/day/rat) was supplied for four weeks in the drinking water. Prostatic hyperplasia was evaluated by histological analysis, DNA content, and/or proliferating cell nuclear antigen (PCNA) expression. Lipoperoxidation (malondialdehyde) and nitrite (NO2^-) levels were analyzed by colorimetric methods, while nitric oxide synthase (NOS), COX, and myeloperoxidase (MPO) enzymes were analyzed using RT-PCR, immunoblotting, and/or enzymatic assays. Levels of 15-F2t-isoprostanes, prostaglandins (PGE₂), leukotrienes (LTB₄), and tumor necrosis factor alpha (TNFα) were measured by ELISA. Control testosterone-treated animals exhibited hyperplasia in the dorsolateral prostate, as well as increments in almost all oxidative parameters except for COX-1, TNFα, or MPO. I₂ and Cxb prevented epithelial hyperplasia (DNA content) and oxidative stress induction generated by testosterone in almost the same intensity, and the minimum I₂ dose required was 2.5mg/rat. The antioxidant capacity of I₂ was also analyzed in a cell-free system, showing that this element inhibited the conversion of nitrate (NO₃^-) to NO₂^-. I₂ did not modify the prostatic oxidative state in testosterone untreated rats. In summary, our data showed that antiproliferative and antioxidant effects of I₂ involve the inhibition of NOS and the COX-2 pathway. Further studies are necessary to analyze the therapeutic and/or adjuvant effects of I₂ with first-line medications used to treat BPH.

Molecular iodine impairs chemoresistance mechanisms, enhances doxorubicin retention and induces downregulation of the CD44+/CD24+ and E-cadherin+/vimentin+ subpopulations in MCF-7 cells resistant to low doses of doxorubicin

One of the most dreaded clinical events for an oncology patient is resistance to treatment. Chemoresistance is a complex phenomenon based on alterations in apoptosis, the cell cycle and drug metabolism, and it correlates with the cancer stem cell phenotype and/or epithelial-mesenchymal transition. Molecular iodine (I2) exerts an antitumor effect on different types of iodine-capturing neoplasms by its oxidant/antioxidant properties and formation of iodolipids. In the present study, wild-type breast carcinoma cells (MCF-7/W) were treated chronically with 10 nM doxorubicin (DOX) to establish a low-dose DOX-resistant mammary cancer model (MCF-7/D). MCF-7/D cells were established after 30 days of treatment when the culture showed a proliferation rate similar to that of MCF-7/W. These DOX-resistant cells also showed increases in p21, Bcl-2 and MDR-1 expression. Supplementation with 200 µM I2 exerted similar effects in both cell lines: it decreased the proliferation rate by ~40%, and I2 co-administration with DOX significantly increased the inhibitory effect (to ~60%) and also increased apoptosis (BAX/Bcl-2 index), principally by inhibiting Bcl-2 expression. The inhibition by I2 + DOX was also accompanied by impaired MDR-1 induction as well as by a significant increase in PPARγ expression. All of these changes could be attributed to enhanced DOX retention and differential down-selection of CD44+/CD24+ and E-cadherin+/vimentin+ subpopulations. I2 + DOX-selected cells showed a weak induction of xenografts in Foxn1nu/nu mice, indicating that the iodine supplements reversed the tumorogenic capacity of the MCF-7/D cells. In conclusion, I2 is able to reduce the drug resistance and invasive capacity of mammary cancer cells exposed to DOX and represents an anti-chemoresistance agent with clinical potential.

Triiodothyronine Attenuates Prostate Cancer Progression Mediated by β-Adrenergic Stimulation

Prostate cancer cells are responsive to adrenergic and thyroid stimuli. It is well established that β-adrenergic activation (protein kinase A [PKA]/cAMP response element binding protein [CREB]) promotes cancer progression, but the role of thyroid hormones is poorly understood. We analyzed the effects of β-adrenergic stimulation (isoproterenol [ISO]) and/or thyroid hormone on neuroendocrine (NE) differentiation and cell invasion, using in vivo (LNCaP tumor) and in vitro models (LNCaP and DU145 human cells). Nude mice were inoculated with LNCaP cells and were treated for 6 wks with ISO (200 μg/d), triiodothyronine (T3, 2.5 μg/d) or both. ISO alone reduced tumor growth but increased tumor expression of cAMP response element (CRE)-dependent genes (real-time polymerase chain reaction, chromogranin A, neuron-specific enolase, survivin, vascular endothelial growth factor [VEGF], urokinase plasmin activator [uPA] and metalloproteinase-9 [MMP-9]) and some proteins related to NE differentiation and/or invasiveness (synaptophysin, VEGF, pCREB). T3 reduced tumor growth and prevented the overexpression of ISO-stimulated factors through a pCREB-independent mechanism. In low invasive LNCaP cells, 50 μmol/L ISO or 100 nmol/L thyroxine (T4) induced the acquisition of NE-like morphology (phase-contrast microscopy), increased VEGF secretion (ELISA) and invasive capacity (Transwell assay), but no synergistic effects were observed after the coadministration of ISO + T4. In contrast, 10 nmol/L T3 alone had no effect, but it prevented the NE-like morphology and invasiveness stimulated by ISO. None of these treatments had any effect on highly invasive DU145 cells. In summary, this study showed that ISO and T4 increase cancer progression, and T3 attenuates ISO-stimulated progression. Further studies are required to determine if changes in the ratio of T4/T3 could be relevant for prostate cancer progression.

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.

6-iodolactone, key mediator of antitumoral properties of iodine

An iodinated derivative of arachidonic acid, 5-hydroxy-6-iodo-8,11,14-eicosatrienoic acid, δ-lactone (6-IL) has been implicated as a possible intermediate in the autoregulation of the thyroid gland by iodine. In addition to antiproliferative and apoptotic effects observed in thyrocytes, this iodolipid could also exert similar actions in cells derived from extrathyroidal tissues like mammary gland, prostate, colon, or the nervous system. In mammary cancer (solid tumors or tumor cell lines), 6-IL has been detected after molecular iodine (I2) supplement, and is a potent activator of peroxisome proliferator-activated receptor type gamma (PPARγ). These observations led us to propose I2 supplement as a novel coadjutant therapy which, by inducing differentiation mechanisms, decreases tumor progression and prevents chemoresistance. Some kinds of tumoral cells, in contrast to normal cells, contain high concentrations of arachidonic acid, making the I2 supplement a potential "magic bullet" that enables local, specific production of 6-IL, which then exerts antineoplastic actions with minimal deleterious effects on normal tissues.

The NMDA receptor antagonist MK-801 abolishes the increase in both p53 and Bax/Bcl2 index induced by adult-onset hypothyroidism in rat

Hypothyroidism affects neuron population dynamics in the hippocampus of the adult rat, with neuronal damage as the main feature of its effect. This effect is prevented by the blockade of NMDA receptors, which suggests that glutamatergic activity mediates cell death in this condition. Glutamate can also stimulate cell proliferation and survival of newborn neurons, indicating that it can affect different stages of the cell cycle. In this work we measured the expression of specific proteins that control cell proliferation (cycline-D1), cell arrest (p21), damage (p53) or apoptosis (Bax and Bcl2) in the hippocampus of hypothyroid rats treated with the NMDA receptor (NMDAR) blocker MK-801 during the induction of hypothyroidism. The results show that hypothyroidism increases the expression of markers of DNA damage, cell arrest, and apoptosis, but does not affect the marker of cell proliferation. NMDAR blockade prevents the increase on markers of DNA damage and apoptosis, but does not influence cell arrest or cell proliferation. This suggests that hypothyroidism promotes cell death mainly by an excitotoxic effect of glutamate.

Iodine uptake and prostate cancer in the TRAMP mouse model

Iodine supplementation exerts antitumor effects in several types of cancer. Iodide (I⁻) and iodine (I₂) reduce cell proliferation and induce apoptosis in human prostate cancer cells (LNCaP and DU-145). Both chemical species decrease tumor growth in athymic mice xenografted with DU-145 cells. The aim of this study was to analyze the uptake and effects of iodine in a preclinical model of prostate cancer (transgenic adenocarcinoma of the mouse prostate [TRAMP] mice/SV40-TAG antigens), which develops cancer by 12 wks of age. ¹²⁵I⁻ and ¹²⁵I₂ uptake was analyzed in prostates from wild-type and TRAMP mice of 12 and 24 wks in the presence of perchlorate (inhibitor of the Na⁺/I⁻ symporter [NIS]). NIS expression was quantified by quantitative polymerase chain reaction (qPCR). Mice (6 wks old) were supplemented with 0.125 mg I⁻ plus 0.062 mg I₂/mouse/day for 12 or 24 wks. The weight of the genitourinary tract (GUT), the number of acini with lesions, cell proliferation (levels of proliferating cell nuclear antigen [PCNA] by immunohistochemistry), p53 and p21 expression (by qPCR) and apoptosis (relative amount of nucleosomes by enzyme-linked immunosorbent assay) were evaluated. In both age-groups, normal and tumoral prostates take up both forms of iodine, but only I⁻ uptake was blocked by perchlorate. Iodine supplementation prevented the overexpression of NIS in the TRAMP mice, but had no effect on the GUT weight, cell phenotype, proliferation or apoptosis. In TRAMP mice, iodine increased p53 expression but had no effect on p21 (a p53-dependent gene). Our data corroborate NIS involvement in I⁻ uptake and support the notion that another transporter mediates I₂ uptake. Iodine did not prevent cancer progression. This result could be explained by a strong inactivation of the p53 pathway by TAG antigens.

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.

Iodine and doxorubicin, a good combination for mammary cancer treatment: antineoplastic adjuvancy, chemoresistance inhibition, and cardioprotection

BACKGROUND

Although mammary cancer (MC) is the most common malignant neoplasia in women, the mortality for this cancer has decreased principally because of early detection and the use of neoadjuvant chemotherapy. Of several preparations that cause MC regression, doxorubicin (DOX) is the most active, first-line monotherapeutic. Nevertheless, its use is limited due to the rapid development of chemoresistance and to the cardiotoxicity caused by free radicals. In previous studies we have shown that supplementation with molecular iodine (I2) has a powerful antineoplastic effect in methylnitrosourea (MNU)-induced experimental models of MC. These studies also showed a consistent antioxidant effect of I2 in normal and tumoral tissues.

METHODS

Here, we analyzed the effect of I2 in combination with DOX treatment in female Sprague Dawley rats with MNU-induced MC. In the first experiment (short) animals were treated with the therapeutic DOX dose (16 mg/kg) or with lower doses (8 and 4 mg/Kg), in each case with and without 0.05% I2 in drinking water. Iodine treatment began on day 0, a single dose of DOX was injected (ip) on day 2, and the analysis was carried out on day 7. In the second experiment (long) animals with and without iodine supplement were treated with one or two injections of 4 mg/kg DOX (on days 0 and 14) and were analyzed on day 56.

RESULTS

At all DOX doses, the short I2 treatment induced adjuvant antineoplastic effects (decreased tumor size and proliferating cell nuclear antigen level) with significant protection against body weight loss and cardiotoxicity (creatine kinase MB, cardiac lipoperoxidation, and heart damage). With long-term I2, mammary tumor tissue became more sensitive to DOX, since a single injection of the lowest dose of DOX (4 mg/Kg) was enough to stop tumor progression and a second DOX4 injection on day 14 caused a significant and rapid decrease in tumor size, decreased the expression of chemoresistance markers (Bcl2 and survivin), and increased the expression of the apoptotic protein Bax and peroxisome proliferator-activated receptor type gamma.

CONCLUSIONS

The DOX-I2 combination exerts antineoplastic, chemosensitivity, and cardioprotective effects and could be a promising strategy against breast cancer progression.

Uptake and antitumoral effects of iodine and 6-iodolactone in differentiated and undifferentiated human prostate cancer cell lines

BACKGROUND

Evidence indicates that iodine per se could be implicated in the physiology of several organs that can internalize it. In thyroid and breast cancer, iodine treatments inhibit cell proliferation and induce apoptosis through a direct (mitochondria) and/or indirect effect (iodolipid generation). Here, we determined the uptake of iodide (I(-) ) and iodine (I(2) ), as well as the antiproliferative and apoptotic effects of 6-iodolactone (6-IL) and both forms of iodine in human prostate cells lines.

METHODS

Non-cancerous (RWPE-1) and cancerous (LNCaP, DU-145) cells, as well as nude mice xenotransplanted with DU-145 cells were used as cancer models. Iodine uptake was analyzed with radioactive tracers, transporter expression by qRT-PCR, cell proliferation by blue trypan, apoptosis by enzyme immunoassay or fluorescence, BAX and BCL-2 by western-blot, and caspsase 3 by enzymatic assay.

RESULTS

All three cell lines take up both forms of iodine. In RWPE-1 cells, I(-) uptake depends on the Na(+) /I(-) symporter (NIS), whereas it was independent of NIS in LNCaP and DU-145 cells. Antiproliferative effects of iodine and 6-IL were dose and time dependent; RWPE-1 was most sensitive to I(-) and 6-IL, whereas LNCaP was more sensitive to I(2) . In the three cell lines both forms of iodine activated the intrinsic apoptotic pathway (increasing the BAX/BCL-2 index and caspases). Iodine supplementation impaired growth of the DU-145 tumor in nude mice.

CONCLUSION

Normal and cancerous prostate cells can take up iodine, and depending on the chemical form, it exerts antiproliferative and apoptotic effects both in vitro and in vivo.

Abstract B38: Iodine supplement exerts antineoplastic adjuvancy, chemoresistance inhibition and cardioprotection in mammary cancer treatment with anthracyclines

Mortality for mammary cancer (MC) has decreased in the past decade, owing principally to early detection and the use of neoadjuvant chemotherapy. Of several preparations that cause regression of MC, Doxorubicin (DOX) is the most active, first-line monotherapeutic. Nevertheless, its use has been limited due to the rapid development of chemoresistance and cardiotoxicity caused by free radicals. In previous studies we have shown that supplementation with moderately high doses of molecular iodine (I2) has a powerful antineoplastic effect in methylnitrosourea (MNU)-induced MC models. These studies also showed a consistent antioxidant effect of I2 in normal and tumoral tissues. In the present study we analyzed the effect of I2 in combination with DOX treatment. Female Sprague Dawley rats with MNU-induced MC were treated with the therapeutic DOX dose (16 mg/kg) and with two lower doses (8 and 4 mg/kg) with and without 0.05% I2 in drinking water. In a first, short-term experiment, iodine treatment began 2 days before a single DOX injection (ip), and the animals were analyzed after 7 days. In a second experiment, animals received two injections (days zero and 14) of 4 mg/kg DOX without or with long-term I2 treatment throughout the 56 days of observation. The results showed that at every DOX dose, short-term I2 treatment induced synergic antineoplastic effects (decreasing tumor size and PCNA signal) with significant protection against body weight loss and cardiotoxicity (CK-MB enzyme and cardiac lipoperoxidation). With long-term I2 treatment, mammary tumors became more sensitive to 4 mg/kg DOX, decreasing chemoresistance markers (Bcl2 and survivin) and increasing peroxisome proliferator-activated receptor type gamma expression, indicating a specific interaction of I2 with these receptors.

The authors thank Felipe Ortóz for his technical assistance and Leonor Casanova for academic supports. Supported in part by PAPIIT/UNAM 201210 and CONACYT 78955.

Citation Format: Carmen Aceves, Yunuen Alfaro-Hernandez, Guadalupe Delgado. Iodine supplement exerts antineoplastic adjuvancy, chemoresistance inhibition and cardioprotection in mammary cancer treatment with anthracyclines. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr B38.

Food-restricted and dehydrated-induced anorexic rats present differential TRH expression in anterior and caudal PVN. Role of type 2 deiodinase and pyroglutamyl aminopeptidase II

TRH synthesized in hypothalamic paraventricular nucleus (PVN) regulates thyroid axis function and is also implicated in anorexigenic effects. Under energy deficit, animals present decreased PVN TRH expression and release, low TSH levels, and increased appetite. Dehydration-induced anorexia (DIA) model allows insight into underlying mechanisms of feeding regulation. Animals drinking a 2.5% NaCl solution for 7 d present body weight reduction; despite their negative energy balance, they avoid food and have increased PVN TRH expression and TSH serum levels. These findings support an inhibiting role of PVN TRH in feeding control. We compared TRH expression by in situ hybridization in PVN subdivisions of 7-d dehydrated male rats to those of a pair-fed group (forced food-restricted) with similar metabolic changes than DIA, but motivated to eat, and to controls. We measured peripheral deiodinase activities, and expression and activity of medial basal hypothalamic type 2 deiodinase and pyroglutamyl-aminopeptidase II, to understand their regulating role in PVN TRH changes between food restriction and anorexia. TRH mRNA levels increased in anterior (aPVN) and medial-caudal subdivisions in DIA rats, whereas it decreased in medial PVN in both experimental groups. We confirmed the nonhypophysiotropic nature of aPVN TRHergic cells by injecting ip fluorogold tracer. Findings support a subspecialization of TRHergic hypophysiotrophic cells that responded differently between anorexic and food-restricted animals; also, that aPVN TRH participates in food intake regulation. Increased type 2 deiodinase activity seemed responsible for low medial PVN TRH synthesis, whereas increased medial basal hypothalamic pyroglutamyl-aminopeptidase II activity in DIA rats might counteract their high TRH release.

Abstract C62: Triiodothyronine (T3) supplementation prevents the overexpresion of invasion factors induced by β-adrenergic stimulation in prostate cancer models

There are multiple pieces of evidence that the sympathetic nervous system and thyroid hormones play crucial roles in normal and cancerous development of tissues. It is well established that chronic β-adrenergic stimulation (cAMP-PKA-CREB pathway) is a risk factor for progression of prostate cancer because it promotes cell migration, tumor invasion, and metastasis. Moreover, studies in human prostate cancer cells (LNCaP) show that a high dose of adrenaline induces transdifferentiation of secretor epithelium into a neuroendocrine phenotype with high invasive potential. Although studies from our group have shown a direct relation between sympathetic-input and prostate T3 generation (which seems to be associated with epithelial differentiation that occurs at puberty), there is no evidence about T3 effects on the progression of prostate cancer. Studies in hepatic cancer show that T3 administration reverses the neoplastic lesions induced by a chemical carcinogen (differentiating effects). The aim of this study was to analyze, in models of prostate cancer (in vivo and in vitro), the effects of β-adrenergic stimulation, T3, or both on tumor progression. Nude mice (nu/nu, 8 weeks old) were subcutaneously transplanted with human prostate cancer cells (LNCaP). Two days later, the mice were implanted in the back with a controlled-release pellet of isoproterenol (ISO, β-adrenergic agonist, 200 μg/day), and T3 was administrated in the drinking water (2.5 μg/day). Single (ISO or T3) or combined treatments (ISO+T3) were maintained for 6 weeks, and body weight, tumor incidence, and tumor volume were registered every week. In prostate tumor, qRT-PCR was used to analyze the expression of genes related to angiogenesis (vascular endothelial growth factor, VEGF), invasion (urokinase plasmin activator, uPA; metalloproteinase 9, MMP9), and neuroendocrine phenotype (chromogranin A, CgA). The results showed that none of the treatments affected body weight. In the ISO and ISO + T3 groups, tumors appeared in week 3, while in control and T3 groups the onset of the tumors occurred by week 5. In comparison with the control group, ISO treatment decreased tumor growth, but increased the expression of VEGF, uPA, MMP9, and CgA (2-3 fold). These effects are consistent with the well known effects of β-adrenergic stimulation on the acquisition of the neuroendocrine phenotype (slowly proliferating but highly invasive tumors). T3 administration prevents the increase of VEGF, uPA, MMP9, and CgA expression induced by ISO. Administration of T3 alone did not modify the tumoral growth or gene expression mentioned above. Migration assays in vitro of LNCaP cells showed that ISO increased cell migration, and T3 prevented the ISO effect (ISO + T3). These findings suggest that T3 might inhibit the transcription of genes dependent on β-adrenergic stimulation in prostate cancer. Current studies are analyzing if the protective effects of T3 might be associated with CREB inactivation.

The authors are grateful to Guadalupe Delgado, Felipe Ortiz, and Martín García for their technical assistance. We thank Dr. Erika Rendón (Facultad de Medicina, UNAM) for her advice for the in vitro assays. Supported by CONACYT (78955, 87196, 127368), PAPIIT (IN201210).

Abstract B40: Uptake and potential antineoplasic effects of iodine on prostate cancer in the TRAMP model

Prostate cancer is the second most frequently diagnosed cancer in men worldwide, but incidence rates vary, being lower in Japan than in the USA. This low incidence in Japanese populations has been explained by the high intake of iodine (5280 μg/day in Japan vs 209 μg in USA), among other factors. Studies in thyroid and breast cancer have shown that iodine supplementation induces apoptosis, reduces cell proliferation, and decreases the expression of cell invasion factors (VEGF, uPa, uPAR). In both tissues, iodide (I−) uptake is mediated by the Na+/I− symporter (NIS), whereas iodine (I2) uptake depends on a facilitated diffusion mechanism. Our group showed that I− or I2 supplementation of rats with prostate hyperplasia (induced with sex hormones) decreases the DNA content and has no harmful effect on normal tissue. In human prostate cancer cells (LNCaP), I− uptake is mediated via NIS, while I2 uptake is independent from NIS. Both I− and I2 treatment activated the apoptotic pathway mediated by Bax/Bcl2, and caspases, suggesting that either form of iodine might be used as an antineoplastic agent against prostate cancer. Here, we determined the uptake of I− and I2 in normal (WT) and tumoral mouse prostate, and analyzed the effect of a mixed iodide/iodine (0.5 mg I−+ 0.25 mg I2) supplement (starting at 6 weeks of age) on the progression of prostate cancer in a transgenic model (Transgenic Adenocarcinoma of Mouse Prostate, TRAMP). The TRAMP mice developed intraepithelial neoplastic lesions (PIN) and cancer around 12 and 24 weeks of age, respectively. Iodine uptake was analyzed with radioactive tracers (125I− and 125I2), which were ip injected into WT and TRAMP mice at these two ages. The radiolabel was quantified at 120 min post-injection in a gamma counter. The results showed that normal and tumoral prostates take up both chemical forms of iodine, but only I− uptake is blocked by the classic NIS inhibitor perchlorate. These data corroborate NIS participation in I− uptake and support the notion that another transporter mediates I2 uptake. Iodine supplementation had no effect on the genitourinary tract weight, histopathological acini aspect (hematoxylin-eosina stain), or proliferative rate (immunoreactivity to proliferating cell nuclear antigen) of any groups. Currently, we are analyzing the effect of iodine on tumor apoptosis and the expression of molecular factors associated with cell invasion and metastasis (epithelial-mesenchymal transition).

The authors are grateful to Felipe Ortiz and Martín García for their technical assistance. Supported by CONACYT (78955, 87196, 127368), PAPIIT (IN201210).

Citation Format: Paloma Olvera, Guadalupe Delgado, Carmen Aceves, Brenda Anguiano. Uptake and potential antineoplasic effects of iodine on prostate cancer in the TRAMP model [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr B40.

Antineoplastic effect of iodine and iodide in dimethylbenz[a]anthracene-induced mammary tumors: association between lactoperoxidase and estrogen-adduct production

Several groups, including ours, have reported that iodine exhibited antiproliferative and apoptotic effects in various cancer cells only if this element is supplemented as molecular iodine, or as iodide, to cells that are able to oxidize it with the enzyme thyroperoxidase. In this study, we analyzed the effect of various concentrations of iodine and/or iodide in the dimethylbenz[a]anthracene (DMBA) mammary cancer model in rats. The results show that 0.1% iodine or iodide increases the expression of peroxisome proliferator-activated receptor type γ (PPARγ), triggering caspase-mediated apoptosis pathways in damaged mammary tissue (DMBA-treated mammary gland) as well as in frank mammary tumors, but not in normal mammary gland. DMBA treatment induces the expression of lactoperoxidase, which participates in the antineoplastic effect of iodide and could be involved in the pro-neoplastic effect of estrogens, increasing the formation of DNA adducts. In conclusion, our results show that a supplement of 0.1% molecular iodine/potassium iodide (0.05/0.05%) exert antineoplastic effects, preventing estrogen-induced DNA adducts and inducing apoptosis through PPARγ/caspases in pre-cancer and cancerous cells. Since this iodine concentration does not modify the cytology (histology, apoptosis rate) or physiology (triiodothyronine and thyrotropin) of the thyroid gland, we propose that it be considered as an adjuvant treatment for premenopausal mammary cancer.

Abstract 3509: Iodine exhibits dual effects on breast cancer as a co-treatment with anthracyclines: Antineoplastic synergy and cardioprotector

Breast cancer (BC) is the most common type of cancer worldwide in reproductive-age women. Genetic (mutations in the gene BRCA), reproductive (menarche, pregnancy, and menopause), and environmental factors (lipids, alcohol, iodine, etc.) are known to be involved in BC etiology. Previous studies have demonstrated that molecular iodine (I2) has an antineoplastic effect on mammary cancer cells in vivo as well as in vitro through activation of caspase-dependant apoptotic pathways. It has also been demonstrated that this element has a powerful antioxidant effect, even greater than that of vitamin E. These dual beneficial effects of I2 were corroborated in rats with methyl-nitrosourea-induced mammary cancers treated with anthracyclines (AC) – an antineoplastic drug that also has a free radical cardiopathic secondary effect but is commonly used in humans. In combination with AC, I2 acted as an adjuvant, decreasing tumoral size and providing significant cardioprotection.

In the present study we did a clinical evaluation of the additive effect of I2 (5 mg/day) or placebo (vegetable dye) with a common antineoplastic cocktail containing AC (Fluorouracil, Epirubicyn, Cyclophosphamide, Taxotere [FEC/TE], four to six cycles) in advanced BC patients (stages III and IV). Preliminary results (N=14) show a significant antineoplastic adjuvant effect of I2 when administered together with FEC/TE, and complete remission in 33 % of the cases. This result permitted conservative surgery on 3 of the 14 patients.

Molecular analysis showed that in the tumoral mass of I2-supplemented patients, there was a significant decrease of the cell proliferation rate, as tested with Proliferating Cell Nuclear Antigen, PCNA immunohistochemistry (98.6% vs 80.8%), and of cyclin D1 expression (1.2 ±0.6 vs 0.3 ± 0.06; real time PCR) when compared with the control group (FEC/TE+ placebo). We also found a significant increase in the apoptosis rate (Terminal deoxynucleotidyl transferase dUTP nick end labeling; TUNEL) in the FEC/TE + I2 group (42.2 ± 4.8 vs 73.2 ± 1.8)

Significantly lower serum levels of the cardiac kinase CK-MB were found in FEC/TE +I2 patients (21.5 ± 3.8 vs 8.0 ± 2.6 UI/ml) indicating a protective effect against myocardial damage. We confirmed the iodine intake of our patients by measuring the levels of this molecule in urine samples (44 ± 4.5 vs 256 ± 13 ug/dl).

In conclusion, our results show a significant dual effect of iodine with FEC/TE that lead us to propose its implementation as a novel treatment for BC that could, in the future, allow lower doses of standard chemotherapy, reducing adverse effects and cost.

Acknowledgements to Biol. Felipe Ortíz and Biol. Paloma Olvera for the technical support, and Dr. Dorothy Pless for proofreading. Study partially supported by UNAM/DGAPA IN201210 and CONACYT 78955

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3509. doi:10.1158/1538-7445.AM2011-3509

Abstract 4224: Differential effect of iodine on the implantation and metastatic potential of xenografts from two different human breast cancer cell lines

In spite of advances in therapeutics and screening programs, breast cancer metastasis to vital organs (brain, lungs, and bone) is the main cause of death of the patients diagnosed with this disease. The process of metastasis requires a series of steps including the expression of several molecular factors that permit the invasion, angiogenesis, and colonization of other organs. Data generated in different laboratories including ours have shown that molecular iodine (I2) exerts a potent antineoplastic effect on in vitro and in vivo cancer models. Molecular analyses of this effect in methylnitrosourea-induced mammary cancer showed that, besides activating the Bax-caspase apoptotic pathway, I2 also interfered with the metastatic potential by decreasing the expression of urokinase-type plasminogen activator (uPA) and vascular endothelial growth factor (VEGF), proteins intimately related to invasion and vascularization, respectively. To determine the role of I2 in the implantation and metastatic potential of human mammary cancer, we used xenografts of two human breast cancer cell lines with different metastatic potential (MCF-7 and MDA-MB231). Female athymic homozygotic (Foxn1 nu/nu) mice (8 weeks old) were injected subcutaneously with 5 million parental cells of each cell line in 50 µl PBS and 50 µl matrigel. Drinking water for the control group was deionized water, which was supplemented with 0.025% I2 for the iodine group. All animals were monitored for 6 weeks at weekly intervals for the development of tumors. Tumor sizes were calculated by the ellipsoid formula, proliferation rate was measured by Proliferating Cell Nuclear Antigen (PCNA) immunohistochemistry, and the metastatic potential was estimated by uPA activity (enzymatic assay).

The results showed that the I2 supplement decreases the implantation capacity (incidence), tumoral growth, and cell proliferation of both cell lines, MDA-MB231 (20%; 0.18 ± 0.08 cm3; 34.8% PCNA-positive cells/field) and MCF-7 (50%; 0.5 ± 0.07 cm3; 34.3% PCNA-positive cells/field) in comparison with the control (95.1%; 2.2 ± 0.3 cm3; 42.8% PCNA-positive cells/field). In contrast, I2 decreased the metastatic potential (uPA activity) only in those tumors that had been generated from MCF-7 (32 ± 5.6 vs 52 ± 2.8 IU/mg protein control).

In conclusion, our data suggest that I2 supplementation interferes primarily with the implantation and proliferation of mammary cancer cells, but it may be ineffective in decreasing the metastatic potential of those cancer cells with a more aggressive phenotype.

Acknowledgements to Biol. Felipe Ortíz, Dr. Laura Vega for the technical support, and Dr. Dorothy Pless for proofreading. Study partially supported by UNAM/DGAPA IN201210 and CONACYT 78955.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4224. doi:10.1158/1538-7445.AM2011-4224

Abstract P6-14-15: Impaired Nuclear Translocation of Estrogen Receptor Alfa Could Be Associated with the Antineoplastic Effect of Iodine in Premenopausal Breast Cancer

Several laboratories including ours have shown that iodine (I2) intake exhibits potent antiproliferative and apoptotic effects in vivo and in vitro models of mammary cancer. Molecular analysis of these effects indicates that antioxidant; cellular arrest and apoptotic pathways are involved. As the cellular mechanism that triggers these antineoplastic effects we have proposed that I2 could act in 2 possible ways, directly as antioxidant or indirectly by generating an iodinated arachidonic acid (6-iodoloctone) which exhibits apoptotic effects and is a specific ligand of proliferative peroxisome activated receptor gamma (PPARg). In previous preliminary reports, we corroborated an antiproliferative I2 effect (decreased PCNA) in premenopausal (pre-M) and an apoptotic action (triggering the Bax-Caspase pathway) in both pre-M and post menopausal (post-M) women with early stage breast cancer. In the present report we raise the casuistic and deeply in the analysis of mechanisms involved in this antineoplastic effect of I2. This study includes 22 women (average age 52.9 ± 12.6) diagnosed with early stage breast cancer (IIa and IIb). Patients were divided according to hormonal status into pre-M and post-M groups and were supplemented with I2 (5 mg daily) or placebo (vegetable dye) for2-5 weeks before surgery. Thyroid status (T3 and TSH; RIA) and iodine intake (urine, HPLC) were analyzed. In biopsies (beginning) and/or tumors (final), the level and location (cytosol or nuclear) of estrogen receptor alfa (ERα) and beta (ERb) were analyzed by immunohistochemistry. In tumors, we measured PPARg expression, invasive potential [hypoxia-inducible factor (HIF) and vascular endothelial growth factor (VEGF) by real time PCR] and fibrosis content (Masson's trichromic method). The results show that I2 supplementation in pre-M women is accompanied by a significant increase in the concentration of total ERα and PPARg and no change in total ERb; however, the fraction of ERα in the nucleus was significant lower, and the fibrosis content was higher (70%) than in the placebo group (40%).

In contrast, I2 supplements significantly decreased HIF and VEGF expression in both pre-and post-M women. In conclusion, our data show that, in addition to the apoptotic and anti-invasive effects on mammary cancer exhibited by I2 that are independent of hormonal status, in pre-M women, I2 also acts to diminish the effects of estrogen (decreases nuclear translocation of ERα). Experiments that analyze the possible role of PPARg in these actions are in progress.

We thank Dr. Jorge Alvarez-Aguirre2,3, Dr. Alonso Gallegos-Corona2, Lic. Concepción Correa-Tinajero3, Alejandro Nuñez-Nolasco2,3, Dra. Norma Uribe Uribe4, Jaime Ayala García4 and Dr. Dorothy Pless1. This work was supported by in part by PAPIIT-UNAM IN201210 and CONACyT 78955 and 85952.

Abstract P5-10-16: Iodine/Anthracyclines Is the Best Combination Against Mammary Cancer. Antineoplastic Synergism and Cardioprotection

Mammary cancer is the world's most common malignant neoplasia for women. Recently, the mortality for breast cancer has fallen due principally to early detection and to use of neoadjuvant chemotherapy. Anthracycline antibiotics are the most commonly used anticancer drugs, and Doxorubicin (DOX) is the first choice to treat mammary cancer. Nevertheless, its use has limited by its cadiotoxic side effects, which are generated by free radicals. Our studies in methylnitrosourea (MNU)-induced mammary cancer models have shown that supplementation with moderately high doses of molecular iodine (I2) exhibits two distinctive and beneficial effects: antineoplastic and antioxidant. In the present work we explored these dual characteristic of I2 (0.05%) as an adjuvant to DOX16 (therapeutic dose of 16 mg/kg) and DOX8 (8 mg/kg) in female Sprague Dawley rats (200 g) with tumors induced by a single dose of 50 mg MNU per Kg. Iodine intake is initiated 2 days before DOX application and continues up to sacrifice 7 days later. The following parameters were registered: body weight, tumor size, tumor proliferation rate (proliferating cell nuclear antigen, PCNA), serum creatinine kinase-MB activity (CK-MB), cardiac lipoperoxidation (cLPO), and cardiac catalase activity (cCAT). Values correspond to mean± SD. Different superscripts represent significant (p≥0.05). Tumor reduction was greater in the DOX16 + I2 group than in the DOX 16 group (75% vs. 50%, respectively), and was associated with a significantly greater decrease in the rate of tumor cell proliferation (25% vs 10% decrease in PCNA-positive cells), showing the synergistic effect of I2. In contrast, at both DOX doses, the DOX + I2, groups had lower body weight loss and less cardiac damage (CK-MB; 280% vs 100%, cLPO 100% vs 0%) than with DOX alone. cCAT was not changed by any of the treatments.Conclusions: Iodine acts as an adjuvant by significantly enhancing the antiproliferative effect of DOX at a therapeutic dose (DOX16), and it exerts significant general and cardiac protective effects that do not involve catalase activation. Cellular and molecular mechanisms involved in these dual effects of iodine are currently being analyzed. The authors thank Drs. Mauricio Diaz, Marcela Lizano, and Brenda Anguiano as well as Biol. Felipe Ortiz for their technical assistance and Leonor Casanova for academic supports. We also thank Dr. Dorothy Pless for proof-reading. Supported in part by PAPIIT/UNAM 201210 and CONACYT 78955 and 47928/47928. Figure available in online version.

Postejaculatory increase of prostatic triiodothyronine (T3) depends on sympathetic innervation in the rat

Thyronines are essential for the development of the male reproductive system, including the prostate gland. Metabolically active 3,5,3' triiodothyronine (T(3)) is generated mainly by the extrathyroidal, enzymatic 5'deiodination of the prohormone thyroxine (T(4)), which is catalyzed by deiodinases type 1 (D1) and type 2 (D2). Prostate D1 activity is highly expressed during puberty and declines with age, but continuous, long-term sexual activity prevents this reduction. The aims of this study were to characterize the changes in prostatic D1 activity in response to consecutive ejaculations and to determine whether sympathetic input participates in the local T(3) generation (D1 activity). D1 activity was analyzed in prostates of sexually experienced, 4-mo-old male rats after one to five ejaculations. D1 activity, T(3) concentrations, and the T(3)-dependent gene ornithine decarboxylase (Odc) were measured after the fourth ejaculation in prostates of intact, sham, and sympathectomized (Smpx, hypogastric nerve) rats. D1 activity was evaluated by the radio-iodine-release method; T(3) was measured by radioimmunoassay and Odc expression by real-time PCR. Data showed a gradual increase of prostate D1 activity in response to consecutive ejaculations. The highest activity was found after the fourth ejaculation, and it decreased after the fifth. The increase of prostate D1 activity after ejaculation was blocked in Smpx males as compared to intact or sham animals. The changes in D1 activity correlate with prostatic T(3) concentrations and Odc expression. Circulating levels of T(3) were not affected by consecutive ejaculations or by Smpx. These findings indicate that the postejaculatory increase in prostatic generation of T(3) depends on sympathetic input.

Type 1 deiodinase activity and generation of triiodothyronine (T3) in prostate of sexually active rats

BACKGROUND

Thyroxine (T(4)) and triiodothyronine (T(3)) are involved in the development and function of the male reproductive system. The type 1 deiodinase enzyme (D1) plays a major role in the intracellular conversion of T(4) to the active form, T(3). D1 is expressed in the prostate of pubescent rats, but it is unknown whether locally generated T(3) is involved in the development and function of this gland.

METHODS

D1 activity was analyzed in prostates from neonatal to old rats. Local T3 generation (D1 and T3 levels) was evaluated in adult animals with 1-5 months of continuous sexual activity. D1 activity was measured by the radiolabeled-iodide-release method and T(3) concentration by radioimmunoassay. Secretory activity of the prostate was evaluated by a morphological analysis of epithelium (hematoxilin-eosin stain) and by measuring the activity of acid phosphatase as a marker enzyme for secretion.

RESULTS

The highest prostate D1 activity was expressed around puberty, and it was almost undetectable during the neonatal period and with aging. Interestingly, 1 and 4 months of sexual activity avoided the decrease of D1 activity associated with aging. Sexual activity provoked a hypertrophy and functional hyperplasia in all lobes, but D1 and acid phosphatase activity increased only in the ventral lobe. D1 activity correlated with an increase in the prostatic T(3) concentration.

CONCLUSIONS

The increased local generation of T(3) in prostate might be related to: (1) the differentiation/maturation that occurs at puberty and (2) the energy expenditure associated with maintaining the secretory activity of the glandular epithelium.

Antineoplastic effect of iodine in mammary cancer: participation of 6-iodolactone (6-IL) and peroxisome proliferator-activated receptors (PPAR)

Introduction

Studies in mammary cancer demonstrated that moderately high concentrations of molecular iodine (I₂) have a antiproliferative and apoptotic effect either in vivo as in vitro, however the cellular intermediated involved in these effects has not been elucidated.

Methods

Virgin Sprague-Dawley rats were treated with methyl-nitrosourea (MNU: single dose ip, 50 mg/Kg bw) and the participation of arachidonic acid (AA) and PPAR receptors in the antineoplasic effect of I₂ where analyzed.

Results

I₂-treated rats for four weeks exhibited a significant reduction in the incidence (62.5 vs. 100%) and size (0.87 ± 0.98 vs 1.96 ± 1.5 cm³) of mammary tumors. HPLC analysis showed that tumoral but not normal mammary tissue contained an elevated basal concentration of AA and significantly more AA-iodinated called 6-iodolactone (6-IL) after chronic I₂ treatment. Tumors from I₂-treated rats showed fewer cells positive to proliferating cell nuclear antigen, lower blood vessel density, as well as decreases in vascular endothelial growth factor, urokinase-type plasminogen activator, and PPAR type alpha (PPARα). These same tumors showed increases in the cell death markers, TUNEL-positive cells (p < 0.05) and the enzyme caspase-3 (trend), as well as significant induction of PPAR type gamma (PPARγ).

Conclusion

Together, these data demonstrate that the antineoplasic effect of iodine involves 6-IL formation and PPARγ induction.

A complex between 6-iodolactone and the peroxisome proliferator-activated receptor type gamma may mediate the antineoplastic effect of iodine in mammary cancer

Recently we and other groups have shown that molecular iodine (I(2)) exhibits potent antiproliferative and apoptotic effects in mammary cancer models. In the human breast cancer cell line MCF-7, I(2) treatment generates iodine-containing lipids similar to 6-iodo-5-hydroxy-eicosatrienoic acid and the 6-iodolactone (6-IL) derivative of arachidonic acid (AA), and it significantly decreases cellular proliferation and induces caspase-dependent apoptosis. Several studies have shown that AA is a natural ligand of the peroxisome proliferator-activated receptors (PPARs), which are nuclear transcription factors thought to participate in regulating cancer cell proliferation. Our results show that in MCF-7 cells: (1) 6-IL binds specifically and with high affinity to PPAR proteins (EMSA assays), (2) 6-IL activates both transfected (by transactivation assays) and endogenous (by lipid accumulation) peroxisome proliferator response elements, and (3) 6-IL supplementation increases PPAR gamma and decreases PPAR alpha expression. These results implicate PPARs in a molecular mechanism by which I(2), through formation of 6-IL, inhibits the growth of human breast cancer cells.

Participation of NMDA-glutamatergic receptors in hippocampal neuronal damage caused by adult-onset hypothyroidism

We analyzed the participation of N-methyl-d-aspartate (NMDA) receptors in the neuronal damage caused by adult-onset hypothyroidism. Wistar rats were randomly assigned into four groups. The euthyroid group received tap water. The hypothyroid group received methimazole (60 mg/kg) in their drinking water to induce hypothyroidism. Two more groups of rats received the antithyroid treatment and were injected daily with the NMDA antagonist ketamine (15 mg/kg, sc) or MK-801 (0.5mg/kg, ip). Treatments were administered during 4 weeks. At the end of the respective treatments rats were deeply anaesthetized and perfused intracardially with 0.9% NaCl followed by 4% paraformaldehyde. The brains were removed from the skull, and coronal brain sections (7microm thick) were obtained. Neurons were counted in the CA1, CA2, CA3, and CA4 hippocampal regions differentiating between normal and atrophic cells by an experimenter blind to the treatment. The percentage of neuronal damage found in the MMI group was significantly greater in the hippocampal regions compared to the euthyroid group. In contrast, both NMDA antagonists were able to prevent the neuronal damage secondary to hypothyroidism in all hippocampal regions. Our results suggest that the neuronal damage caused in the hippocampus of adult-onset hypothyroid rats requires activation of NMDA channels.

The antineoplasic effect of molecular iodine on human mammary cancer involves the activation of apoptotic pathways and the inhibition of angiogenesis

Abstract #3082

Breast cancer is the most frequent malignant neoplasia in women. One factor thought to influence the incidence of breast cancer is diet. Japanese women, who have a high dietary intake of iodine (5280 vs 209 µg/day in western population) due to ingestion of seaweed, have the lowest incidence of breast cancer in the world. In normal mammary gland, iodine deficiency is involved in dysplasias, which are reversible with I2 but not with iodide administration. Recent data generated in our laboratory showed that continuous treatment with I2, but not iodide, has a potent antineoplastic effect on tumoral progression in N-methyl-N-nitrosourea-treated virgin rats (50-70%). Also I2 treatment in MCF-7 human breast cancer cells, but not in normal mammary cells (MCF-12F), shows a significant apoptotic effect induced by activation of Bax-caspases and AIF-PARP-1 pathways. Based on these findings, a study of women diagnosed with cancer (mammography and tru-cut biopsy) was initiated. Patients were divided into placebo or I2 (5 mg/day) groups for 2 to 5 weeks before surgery. One day before beginning the I2 treatment and the day of the surgery, urine and blood samples were collected. The day before surgery, a second mammography was obtained. In the tumor samples proliferation (PCNA), apoptosis (TUNEL), and vasculature area (CD-31) were analyzed by immunohistochemistry. Bax, Bcl2, p53, and VEGF proteins were analyzed by Western blot. Circulating TSH and T3 levels were measured by RIA and urinary iodide by HPLC. The results showed that although tumor size did not differ between groups, a significantly lower proliferation and increased apoptotic rate were observed in tumors from women supplemented with iodine. In these tumors the ratio Bax/Bcl2 increased, p53 levels were unchanged, and VEGF levels and vasculature area diminished significantly. Serum TSH and T3 showed no changes in any group, indicating that I2 treatment had not compromised the thyroid status. We propose that I2 supplements should be considered for use in clinical trials of breast cancer therapies. We thank Dr. Jorge Álvarez-Aguirre2,3, Dr. Alonso Gallegos-Corona2, Lic. Concepción Correa-Tinajero3, Alejandro Núñez-Nolasco2,3, and Silvia Serrato-Águila2. This work was partially supported by: PAPIIT-UNAM IN201207, and CONACyT 44976-M and 85952.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3082.

Signaling pathways involved in the antiproliferative effect of molecular iodine in normal and tumoral breast cells: evidence that 6-iodolactone mediates apoptotic effects

Previous reports have documented the antiproliferative properties of I(2) and the arachidonic acid (AA) derivative 6-iodolactone (6-IL) in both thyroid and mammary glands. In this study, we characterized the cellular pathways activated by these molecules and their effects on cell cycle arrest and apoptosis in normal (MCF-12F) and cancerous (MCF-7) breast cells. Low-to-moderate concentrations of I(2) (10-20 microM) cause G1 and G2/M phase arrest in MCF-12F and caspase-dependent apoptosis in MCF-7 cells. In normal cells, only high doses of I(2) (40 microM) induced apoptosis, and this effect was mediated by poly (ADP-ribose) polymerase-1 (PARP1) and the apoptosis-induced factor, suggesting an oxidative influence of iodine at high concentrations. Our data indicate that both I(2) and 6-IL trigger the same intracellular pathways and suggest that the antineoplasic effect of I(2) in mammary cancer involves the intracellular formation of 6-IL. Mammary cancer cells are known to contain high concentrations of AA, which might explain why I(2) exerts apoptotic effects at lower concentrations only in tumoral cells.

Epididymis expresses the highest 5'-deiodinase activity in the male reproductive system: kinetic characterization, distribution, and hormonal regulation

We characterized the enzymes that catalyze the deiodination of T(4) to T(3) in the male reproductive tract. Testis, epididymis (EPI), seminal vesicles, prostate, bulbourethral glands, spermatozoa, and semen were taken from sexually mature rats (300 g). Iodothyronine 5'-deiodinase (5'-D) activity was quantified by the radiolabeled-iodide-release method. 5'-D activity was 10-fold higher in EPI and semen than in the rest of the tissues. In EPI, semen, and prostate, the enzymatic activity was completely inhibited by 1 mm 6-n-propyl-2-thiouracil, whereas in the other tissues the inhibition was partial (50%). The high susceptibility to 6-n-propyl-2-thiouracil inhibition, a ping-pong kinetic pattern, and low cofactor (Michaelis Menten constant for dithiothreitol=0.7 mm) and high substrate (Michaelis Menten constant for reverse T(3)=0.4 microm) requirements indicate that EPI 5'-D corresponds to type 1 deiodinase (D1). Real-time RT-PCR amplification of D1 mRNA in this tissue confirms this conclusion. The highest EPI D1 expression occurred at the onset of puberty and sexual maturity, and in the adult, this activity was more abundant in corpus and caput than in the caudal region. EPI D1 expression was elevated under conditions of hyperthyroidism and with addition of 17beta-estradiol. Our data also showed a direct association between D1 and a functional epididymis marker, the neutral alpha-glucosidase enzyme, suggesting that local generation of T(3) could be associated with the development and function of EPI and/or spermatozoa maturation. Further studies are necessary to analyze the possible physiological relevance of 5'-D in the male reproductive system.

Uptake and antiproliferative effect of molecular iodine in the MCF-7 breast cancer cell line

This study analyzes the uptake and antiproliferative effect of two different chemical forms of iodine, iodide (I-) and molecular iodine (I2), in MCF-7 cells, which are inducible for the Na+/I- symporter (NIS) and positive for pendrin (PDS). The mouse fibroblast cell line NIH3T3 was used as control. Our results show that in MCF-7 cells, I- uptake is sustained and dependent on NIS, whereas I2 uptake is transient with a maximal peak at 10 min and a final retention of 10% of total uptake. In contrast, no I- was taken up by NIH3T3 cells, and although I2 was captured with the same time pattern as in MCF-7 cells, its uptake was significantly lower, and it was not retained within the cell. The uptake of I2 is independent of NIS, PDS, Na+, and energy, but it is saturable and dependent on protein synthesis, suggesting a facilitated diffusion system. Radioiodine was incorporated into protein and lipid fractions only with I2 treatment. The administration of non-radiolabeled I2 and 6-iodo-5-hydroxy-8,11,14-eicosatrienoic acid (6-iodolactone, an iodinated arachidonic acid), but not KI, significantly inhibited proliferation of MCF-7 cells. Proliferation of NIH3T3 cells was not inhibited by 20 microM I2. In conclusion, these results demonstrate that I2 uptake does not depend on NIS or PDS; they suggest that in mammary cancer cells, I2 is taken up by a facilitated diffusion system and then covalently bound to lipids or proteins that, in turn, inhibit proliferation.

Deiodinase type 1 activity is expressed in the prostate of pubescent rats and is modulated by thyroid hormones, prolactin and sex hormones

The aim of this study was to characterize the type of 5'-deiodinase activity in the prostate of pubescent rats (7-8 weeks), to establish its distribution in the lobes (ventral, dorsolateral, and anterior), and to analyze its modulation by prolactin (PRL), testosterone, dihydrotestosterone (DHT), and 17beta-estradiol (E(2)). Our results showed that the enzymatic activity was highly susceptible to inhibition by 6-n-propyl-2-thiouracil and gold thioglucose, its preferential substrate was reverse tri-iodothyronine (rT(3)), it exhibited a low dithiothreitol requirement (5 mM), and the apparent K(m) and V(max) values for substrate (rT(3)) were approximately 0.25 microM and 9.0 pmol liberated/mg protein per hour, respectively. All these characteristics indicate the preferential expression of type 1 deiodinase (D1), which was corroborated by demonstrating the presence of D1 mRNA in prostate. D1 activity was detected in all lobes and was most abundant in the dorsolateral. Although we detected type 2 deiodinase (D2) mRNA expression, the D2 activity was almost undetectable. D1 activity was enhanced in animals with hyperthyroidism and hyperprolactinemia, in intact animals treated with finasteride (inhibitor of local DHT production), and in castrated animals with E(2) replacement. In contrast, activity diminished in castrated animals with testosterone replacement. Our results suggest that thyroid hormones, PRL, and E(2) exert a positive modulation on D1 activity, while testosterone and DHT exhibit an inhibitory effect. D1 activity may be associated with prostate maturation and/or function.