Iodide transport and breast cancer

Blood Iodine as a Potential Marker of the Risk of Cancer in BRCA1 Carriers

Breast cancer and ovarian cancer pose a significant risk for BRCA1 carriers, with limited risk-reduction strategies. While improved screening helps in the early detection of breast cancer, preventive measures remain elusive. Emerging evidence suggests a potential link between iodine levels and modulation of cancer risk, but comprehensive studies are scarce. We conducted a prospective study among 989 BRCA1 carriers to assess the association between blood iodine levels and breast and ovarian cancer risk. Using inductively coupled plasma mass spectrometry, we measured blood iodine levels and observed a negative association with breast cancer risk, with a significantly lower risk observed in quartile 4 (iodine > 38.0 µg/L) compared with quartile 1 (iodine < 30 µg/L) (HR = 0.49; 95%CI: 0.27-0.87; p = 0.01). Conversely, a suggestive increase in ovarian cancer risk was observed at higher iodine levels (HR = 1.91; 95%CI: 0.64-5.67; p = 0.25). No significant association was found between iodine levels and overall cancer risk. Our results suggest the potential of iodine to reduce breast cancer risk in BRCA1 carriers after prophylactic oophorectomy but require further validation and investigation of its effect on ovarian cancer risk and overall mortality. These findings highlight the need for personalized strategies to manage cancer risk in BRCA1 carriers.

Mechanisms of Sodium/Iodide Symporter-Mediated Mammary Gland Iodine Compensation during Lactation

This research aimed to investigate the compensation mechanism of iodine deficiency and excess in the mammary gland during lactation. Female rats were divided into the low iodine group (LI), the normal iodine group (NI), the 10-fold high iodine group (10HI) and the 50-fold high iodine group (50HI). We measured the iodine levels in the urine, blood, milk, and mammary gland. The protein expression of sodium/iodide symporter (NIS), DPAGT1, and valosin-containing protein (VCP) in the mammary gland was also studied. The 24-hour urinary iodine concentration, serum total iodine concentration, serum non-protein-bound iodine concentration, breast milk iodine concentration, and mammary gland iodine content in the 50HI group were significantly higher than those in the NI group (p < 0.05). Compared with the NI group, NIS expression in the 50HI group significantly decreased (p < 0.05). DAPGT1 expression was significantly higher in the LI group than in the NI group (p < 0.05). The expression level of VCP was significantly increased in the 10HI and 50HI groups. In conclusion, milk iodine concentration is positively correlated with iodine intake, and the lactating mammary gland regulates the glycosylation and degradation of NIS by regulating DPAGT1 and VCP, thus regulating milk iodine level. However, the mammary gland has a limited role in compensating for iodine deficiency and excess.

The Role of Iodine for Thyroid Function in Lactating Women and Infants

Iodine is a micronutrient needed for the production of thyroid hormones, which regulate metabolism, growth, and development. Iodine deficiency or excess may alter the thyroid hormone synthesis. The potential effects on infant development depend on the degree, timing, and duration of exposure. The iodine requirement is particularly high during infancy because of elevated thyroid hormone turnover. Breastfed infants rely on iodine provided by human milk, but the iodine concentration in breast milk is determined by the maternal iodine intake. Diets in many countries cannot provide sufficient iodine, and deficiency is prevented by iodine fortification of salt. However, the coverage of iodized salt varies between countries. Epidemiological data suggest large differences in the iodine intake in lactating women, infants, and toddlers worldwide, ranging from deficient to excessive intake. In this review, we provide an overview of the current knowledge and recent advances in the understanding of iodine nutrition and its association with thyroid function in lactating women, infants, and toddlers. We discuss risk factors for iodine malnutrition and the impact of targeted intervention strategies on these vulnerable population groups. We highlight the importance of appropriate definitions of optimal iodine nutrition and the need for more data assessing the risk of mild iodine deficiency for thyroid disorders during the first 2 years in life.

Thyroid Gene Mutations in Pregnant and Breastfeeding Women Diagnosed With Transient Congenital Hypothyroidism: Implications for the Offspring's Health

Fetus and infants require appropriate thyroid hormone levels and iodine during pregnancy and lactation. Nature endorses the mother to supply thyroid hormones to the fetus and iodine to the lactating infant. Genetic variations on thyroid proteins that cause dyshormonogenic congenital hypothyroidism could in pregnant and breastfeeding women impair the delivery of thyroid hormones and iodine to the offspring. The review discusses maternal genetic variations in thyroid proteins that, in the context of pregnancy and/or breastfeeding, could trigger thyroid hormone deficiency or iodide transport defect that will affect the proper development of the offspring.

Cyclometalated Ru(II) β-carboline complexes induce cell cycle arrest and apoptosis in human HeLa cervical cancer cells via suppressing ERK and Akt signaling

Two new cyclometalated Ru(II)-β-carboline complexes, [Ru(dmb)₂(Cl-Ph-βC)](PF₆) (dmb = 4,4'-dimethyl-2,2'-bipyridine; Cl-Ph-βC = Cl-phenyl-9H-pyrido[3,4-b]indole; RuβC-3) and [Ru(bpy)₂(Cl-Ph-βC)](PF₆) (bpy = 2,2'-bipyridine; RuβC-4) were synthesized and characterized. The Ru(II) complexes display high cytotoxicity against HeLa cells, the stabilized human cervical cancer cell, with IC₅₀ values of 3.2 ± 0.4 μM (RuβC-3) and 4.1 ± 0.6 μM (RuβC-4), which were considerably lower than that of non-cyclometalated Ru(II)-β-carboline complex [Ru(bpy)₂(1-Py-βC)] (PF₆)₂ (61.2 ± 3.9 μM) by 19- and 15-folds, respectively. The mechanism studies indicated that both Ru(II) complexes could significantly inhibit HeLa cell migration and invasion, and effectively induce G0/G1 cell cycle arrest. The new Ru(II) complexes could also trigger apoptosis through activating caspase-3 and poly (ADP-ribose) polymerase (PARP), increasing the Bax/Bcl-2 ratio, enhancing reactive oxygen species (ROS) generation, decreasing mitochondrial membrane potential (MMP), and inducing cytochrome c release from mitochondria. Further research revealed that RuβC-3 could deactivate the ERK/Akt signaling pathway thus inhibiting HeLa cell invasion and migration, and inducing apoptosis. In addition, RuβC-3-induced apoptosis in HeLa cells was closely associated with the increase of intracellular ROS levels, which may act as upstream factors to regulate ERK and Akt pathways. More importantly, RuβC-3 exhibited low toxicity on both normal BEAS-2B cells in vitro and zebrafish embryos in vivo. Consequently, the developed Ru(II) complexes have great potential on developing novel low-toxic anticancer drugs.

Causes of False-Positive Radioactive Iodine Uptake in Patients with Differentiated Thyroid Cancer

Purpose

Radioactive iodine (RAI) whole-body scan is a sensitive imaging modality routinely used in patients with differentiated thyroid cancer to detect persistent and recurrent disease. However, there can be false-positive RAI uptake that can lead to misdiagnosis and misclassification of a patient’s cancer stage. Recognizing the causes of false positivity can avoid unnecessary testing and treatment as well as emotional stress. In this review, we discuss causes and summarize various mechanisms for false-positive uptake.

Recent Findings

We report a patient with differentiated thyroid cancer who was found to have Mycobacterium avium complex infection as the cause of false-positive RAI uptake in the lungs. Using this case example, we discuss and summarize findings from the literature on etiologies of false-positive RAI uptake. We also supplement additional original images illustrating other examples of false RAI uptake.

Summary

False-positive RAI uptake may arise from different causes and RAI scans need to be interpreted in the context of the patient’s history and corresponding cross-sectional imaging findings on workup. Understanding the potential pitfalls of the RAI scan and the mechanisms underlying false uptake are vital in the care of patients with differentiated thyroid cancer.

Defending Effects of Iodide Transfer in Placental Barrier Against Maternal Iodine Deficiency

Objective: Placental iodide transport is necessary for maintaining an adequate iodide supply to the developing fetus. We hypothesized that compounds from the placental barrier can compensate for decreases in maternal iodine intake and normalize fetal iodine levels. Methods: Pregnant rats administered different amounts of iodine (1.24, 2.5, 5, or 10 μg/day) were evaluated on gestational day (gd) 16 and 20. The iodine levels in maternal blood, amniotic fluid (AF), and placental tissue were estimated using As-Ce catalytic spectrophotometry. The protein and/or messenger RNA (mRNA) levels of sodium iodide symporter (NIS), pendrin, alpha-smooth muscle actin (α-SMA), and CD31 in the placental labyrinth, trophoblast cells isolated using laser capture microdissection (LCM), and/or fetomaternal thyroid were detected using immunoblotting, real-time polymerase chain reaction, and/or immunohistochemistry. Results: When iodine intake was reduced, iodine levels in maternal blood gradually decreased; however, placental iodine levels were not significantly different between groups on gd16 and gd20. Minimal changes were observed in AF iodine levels on gd16, and a mild decreasing trend was observed (iodine dose, 10 to 1.24 μg/day) on gd20. NIS protein, which was linearly distributed along the basolateral membrane of maternal-fetal thyroid follicles, gradually increased with decreasing iodine levels. Regarding iodine deficiency in the placental labyrinth on gd16 and gd20, pendrin and glycosylated NIS proteins were significantly upregulated in a dose-dependent manner. However, the mRNA levels were unchanged. Furthermore, the conversion of NIS protein from the nonglycosylated to the glycosylated form increased. In trophoblast cells isolated using LCM, PDS mRNA levels increased in the 1.24-μg/day group on gd16 but not NIS mRNA levels. There was a smaller α-SMA+ area in the labyrinth zone on gd16 and gd20; however, the proportional CD31+ area increased on gd16 and reduced on gd20 with decreased iodine levels. Conclusions: All mechanisms upregulating the expression of iodine transporters and changes in villous stroma and microvessel area in the placental labyrinth can promote iodide transfer from mother to fetus in iodine deficiency, especially before the onset of fetal thyroid function. Compensatory NIS protein regulation in the placenta against decreased iodine intake mainly occurs during translation and glycosylation modification after translation. Pendrin may be more important than NIS in the mediation of placental iodide transport.

Association of Radioiodine for Differentiated Thyroid Cancer and Second Breast Cancer in Female Adolescent and Young Adult

BACKGROUND

Exposure to radiation is related to breast cancer occurrence. While whether the radioiodine (RAI) increases the risk of second breast cancer (SBC) in female differentiated thyroid cancer (DTC) patients is not well addressed.

METHODS

All patients were identified from Surveillance, Epidemiology, and End Results database. At least a 5-year latency was guaranteed since exposure to RAI. Fine and Gray model was used to calculate the cumulative incidence and hazards ratios (HR) and 95% confidence interval (CI). Standardized incidence ratio (SIR) was calculated by Poisson regression analysis. Propensity score matching was used for match analysis. Survival analyses were performed by the Kaplan-Meier method and the log-rank test.

RESULTS

A total of 406 out of 16,850 patients in the RAI group and 733 out of 22,135 patients in the no RAI group developed SBC. The cumulative incidences of SBC were higher in patients with RAI compared with patients without RAI in the adolescent and young adult (AYA) group and the middle-aged adult group. In the AYA group, patients with RAI had increased HR (1.65; 95% CI, 1.33-2.05, p < 0.001) compared with those without RAI, and the HR increased slightly with latency. In addition, the SIR (1.21; 95% CI, 1.02-1.44, p < 0.05) increased compared with the general population. Whereas, in the middle-aged adult group, only a slightly higher HR (1.18) was found. The survival after SBC was inferior to those with matched only primary breast cancer.

CONCLUSIONS

RAI treatment increased the risk of SBC in female AYA DTC patients. A long-term follow-up should be performed in this population.

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.

Feasibility Study Shows Multicenter, Observational Case-Control Study Is Practicable to Determine Risk of Secondary Breast Cancer in Females With Differentiated Thyroid Carcinoma Given Radioiodine Therapy in Their Childhood or Adolescence; Findings Also Suggest Possible Fertility Impairment in Such Patients

Objective: This single-center, observational case-control feasibility study sought to test key elements of a protocol for an eventual long-term international observational case-control study of a larger patient cohort, to evaluate the risk of breast cancer as a second primary malignancy in females with differentiated thyroid cancer (DTC) given radioiodine therapy (RAI) during childhood or adolescence. Patients: Females developing DTC after the Chernobyl accident in Belarus and ≤19 years old at the time of thyroid surgery were enrolled: patients given RAI (n = 111) and controls of similar age not given RAI (n = 90). Results: One case of breast cancer was newly diagnosed among the RAI patients, but none in controls. Patients given RAI significantly less frequently needed 2^nd surgeries than did controls (23%, 26/111 vs. 39%, 35/90, P < 0.05); the main indication for such procedures usually is suspicion of local recurrence. RAI patients appeared to have had more frequent reproductive difficulties than did controls: 78% (87/111) of the former vs. 93% (84/90) of the latter had a history of pregnancy (P < 0.01), and the mean number of pregnancies was 1.5 ± 1.2 in RAI patients vs. 1.9±1.1 in controls (P < 0.05). Most notably, infertility was observed in 23% (26/111) of RAI patients vs. 4% (4/90) of controls (P < 0.01). In conclusion, a international observational case-control study on breast cancer after DTC in patients given RAI vs. not given RAI appears to be feasible. Additional research and everyday clinical attention should be devoted to reproductive function after RAI in young females.

Breast Cancer After Treatment of Differentiated Thyroid Cancer With Radioiodine in Young Females: What We Know and How to Investigate Open Questions. Review of the Literature and Results of a Multi-Registry Survey

Published studies on the risk of radiation-induced second primary malignancy (SPM) after radioiodine treatment (RAI) of differentiated thyroid cancer (DTC) refer mainly to patients treated as middle-aged or older adults and are not easily generalizable to those treated at a younger age. Here we review available literature on the risk of breast cancer as an SPM after RAI of DTC with a focus on females undergoing such treatment in childhood, adolescence, or young adulthood. Additionally, we report the results of a preliminary international survey of patient registries from academic tertiary referral centers specializing in pediatric DTC. The survey sought to evaluate the availability of sufficient patient data for a potential international multicenter observational case-control study of females with DTC given RAI at an early age. Our literature review identified a bi-directional association of DTC and breast cancer. The general breast cancer risk in adult DTC survivors is low, ~2%, slightly higher in females than in males, but presumably lower, not higher, in those diagnosed as children or adolescents than in those diagnosed at older ages. RAI presumably does not substantially influence breast cancer risk after DTC. However, data from patients given RAI at young ages are sparse and insufficient to make definitive conclusions regarding age dependence of the risk of breast cancer as a SPM after RAI of DTC. The preliminary analysis of data from 10 thyroid cancer registries worldwide, including altogether 6,449 patients given RAI for DTC and 1,116 controls, i.e., patients not given RAI, did not show a significant increase of breast cancer incidence after RAI. However, the numbers of cases and controls were insufficient to draw statistically reliable conclusions, and the proportion of those receiving RAI at the earliest ages was too low.In conclusion, a potential international multicenter study of female patients undergoing RAI of DTC as children, adolescents, or young adults, with a sufficient sample size, is feasible. However, breast cancer screening of a larger cohort of DTC patients is not unproblematic for ethical reasons, due to the likely, at most slightly, increased risk of breast cancer post-RAI and the expected ~10% false-positivity rate which potentially produced substantial "misdiagnosis."

Functional analysis and clinical significance of sodium iodide symporter expression in gastric cancer

BACKGROUND

Recent studies have described important roles for the sodium iodide symporter (NIS) in tumor behavior. The objectives of the present study were to investigate the role of NIS in the regulation of genes involved in tumor progression and the clinicopathological significance of its expression in gastric cancer (GC).

METHODS

In human GC cell lines, knockdown experiments were conducted using NIS siRNA, and the effects on proliferation, survival, and cellular movement were analyzed. The gene expression profiles of cells were examined using a microarray analysis. An immunohistochemical analysis was performed on 145 primary tumor samples obtained from GC patients.

RESULTS

NIS was strongly expressed in MKN45 and MKN74 cells. The depletion of NIS inhibited cell proliferation, migration, and invasion and induced apoptosis. The results of the microarray analysis revealed that various interferon (IFN) signaling-related genes, such as STAT1, STAT2, IRF1, and IFIT1, were up-regulated in NIS-depleted MKN45 cells. Furthermore, the down-regulation of NIS affected the phosphorylation of MAPKs and NF-kB. Immunohistochemical staining showed that NIS was primarily located in the cytoplasm or cell membranes of carcinoma cells, and its expression was related to the histological type or venous invasion. Prognostic analyses revealed that the strong expression of NIS was associated with shorter postoperative survival.

CONCLUSIONS

These results suggest that NIS regulates tumor progression by affecting IFN signaling, and that its strong expression is related to a worse prognosis in patients with GC. These results provide an insight into the role of NIS as a mediator and/or a biomarker for GC.

Breast Milk Iodine Concentration Is a More Accurate Biomarker of Iodine Status Than Urinary Iodine Concentration in Exclusively Breastfeeding Women

Background: Iodine status in populations is usually assessed by the median urinary iodine concentration (UIC). However, iodine is also excreted in breast milk during lactation; thus, breast milk iodine concentration (BMIC) may be a promising biomarker of iodine nutrition in lactating women. Whether the mammary gland can vary fractional uptake of circulating iodine in response to changes in dietary intake is unclear.Objective: We evaluated UIC and BMIC as biomarkers for iodine status in lactating women with a wide range of iodine intakes.Methods: We recruited 866 pairs of lactating mothers and exclusively breastfed infants from 3 iodine-sufficient study sites: Linfen, China (n = 386); Tuguegarao, Philippines (n = 371); and Zagreb, Croatia (n = 109). We also recruited iodine-deficient lactating women from Amizmiz, Morocco (n = 117). We collected urine and breast milk samples and measured UIC and BMIC.Results: In the 3 iodine-sufficient sites, a pooled regression analysis of the estimated iodine excretion revealed higher fractional iodine excretion in breast milk than in urine at borderline low iodine intakes. In contrast, in the iodine-deficient site in Morocco, a constant proportion (∼33%) of total iodine was excreted into breast milk.Conclusions: In iodine-sufficient populations, when iodine intake in lactating women is low, there is increased partitioning of iodine into breast milk. For this reason, maternal UIC alone may not reflect iodine status, and BMIC should also be measured to assess iodine status in lactating women. Our data suggest a BMIC reference range (2.5th and 97.5th percentiles) of 60-465 μg/kg in exclusively breastfeeding women. This trial was registered at clinicaltrials.gov as NCT02196337.