Cell-type-dependent thyroid hormone effects on glioma tumor cell lines

The Musashi-1-type 2 deiodinase pathway regulates astrocyte proliferation

Thyroid hormone (TH) is a critical regulator of cellular function and cell fate. The circulating TH level is relatively stable, while tissue TH action fluctuates according to cell type-specific mechanisms. Here, we focused on identifying mechanisms that regulate TH action through the type 2 deiodinase (D2) in glial cells. Dio2 mRNA has an unusually long 3'UTR where we identified multiple putative MSI1 binding sites for Musashi-1 (MSI1), a highly conserved RNA-binding cell cycle regulator. Binding to these sites was confirmed through electrophoretic mobility shift assay. In H4 glioma cells, shRNA-mediated MSI1 knockdown increased endogenous D2 activity, whereas MSI1 overexpression in HEK293T cells decreased D2 expression. This latter effect could be prevented by the deletion of a 3.6 kb region of the 3'UTR of Dio2 mRNA containing MSI1 binding sites. MSI1 immunoreactivity was observed in 2 mouse Dio2-expressing cell types, that is, cortical astrocytes and hypothalamic tanycytes, establishing the anatomical basis for a potential in vivo interaction of Dio2 mRNA and MSl1. Indeed, increased D2 expression was observed in the cortex of mice lacking MSI1 protein. Furthermore, MSI1 knockdown-induced D2 expression slowed down cell proliferation by 56% in primary cultures of mouse cortical astrocytes, establishing the functionality of the MSI1-D2-T3 pathway. In summary, Dio2 mRNA is a target of MSI1 and the MSI1-D2-T3 pathway is a novel regulatory mechanism of astrocyte proliferation with the potential to regulate the pathogenesis of human glioblastoma.

Involvement of Thyroid Hormones in Brain Development and Cancer

The development and maturation of the mammalian brain are regulated by thyroid hormones (THs). Both hypothyroidism and hyperthyroidism cause serious anomalies in the organization and function of the nervous system. Most importantly, brain development is sensitive to TH supply well before the onset of the fetal thyroid function, and thus depends on the trans-placental transfer of maternal THs during pregnancy. Although the mechanism of action of THs mainly involves direct regulation of gene expression (genomic effects), mediated by nuclear receptors (THRs), it is now clear that THs can elicit cell responses also by binding to plasma membrane sites (non-genomic effects). Genomic and non-genomic effects of THs cooperate in modeling chromatin organization and function, thus controlling proliferation, maturation, and metabolism of the nervous system. However, the complex interplay of THs with their targets has also been suggested to impact cancer proliferation as well as metastatic processes. Herein, after discussing the general mechanisms of action of THs and their physiological effects on the nervous system, we will summarize a collection of data showing that thyroid hormone levels might influence cancer proliferation and invasion.

Glioma-derived exosomes drive the differentiation of neural stem cells to astrocytes

Exosomes appear to be effective inter-cellular communicators delivering several types of molecules, such as proteins and RNAs, suggesting that they could influence neural stem cell (NSC) differentiation. Our RNA sequencing studies demonstrated that the RNAs related to cell proliferation and astrocyte differentiation were upregulated in human mesenchymal stem cells (hMSC) when co-cultured with exosomes obtained from the culture medium of human glioma cells (U87). Metallothionein 3 and elastin genes, which are related to cell proliferation, increased 10 and 7.2 fold, respectively. Expression of genes for astrocyte differentiation, such as tumor growth factor alpha, induced protein 3 of the NOTCH1 family, colony stimulating factor and interleukin 6 of the STAT3 family and Hes family bHLH transcription factor 1 also increased by 2.3, 10, 4.7 and 2.9 fold, respectively. We further examined the effects of these exosomes on rat fetal neural stem cell (rNSC) differentiation using the secreted exosomes from U87 glioma cells or exosomes from U87 cells that were stimulated with interleukin 1β (IL-1β). The rNSCs, extracted from rat brains at embryonic day 14 (E14), underwent a culture protocol that normally leads to predominant (~90%) differentiation to ODCs. However, in the presence of the exosomes from untreated or IL-1β-treated U87 cells, significantly more cells differentiated into astrocytes, especially in the presence of exosomes obtained from the IL-1β-challenged glioma cells. Moreover, glioma-derived exosomes appeared to inhibit rNSC differentiation into ODCs or astrocytes as indicated by a significantly increased population of unlabeled cells. A portion of the resulting astrocytes co-expressed both CD133 and glial fibrillary acidic protein (GFAP) suggesting that exosomes from U87 cells could promote astrocytic differentiation of NSCs with features expected from a transformed cell. Our data clearly demonstrated that exosomes secreted by human glioma cells provide a strong driving force for rat neural stem cells to differentiate into astrocytes, uncovering potential pathways and therapeutic targets that might control this aggressive tumor type.

Common genetic variations of deiodinase genes and prognosis of brain tumor patients

BACKGROUND

Thyroid hormone (TH) metabolism can have prognostic significance in brain tumors. We studied the association of common variations in three deiodinase gene single-nucleotide polymorphisms (SNPs) with circulating TH concentrations and prognosis of brain tumor patients.

METHODS

Patients admitted for glioma and meningioma surgery between January, 2010 and September, 2011 were evaluated for functional status (Barthel Index or BI) and circulating free tri-iodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) concentrations. Ten common SNPs in the DIO1 gene; five SNPs in the DIO2 gene; and one SNP in the DIO3 gene were genotyped. Follow-up continued until November, 2017.

RESULTS

In glioblastoma patients, the DIO1 SNP rs2235544 CC genotype was associated with significantly lower risk of death at 2 years when compared to AA + CA genotypes after adjusting for patient gender, age, pre-operative functional status, adjuvant therapy, and extent of resection (HR = 0.34, 95% CI: 0.13-0.84, p = 0.019). The TT genotype vs. CC + TC genotypes of the DI02 SNP rs12885300 was associated with increased mortality risk after adjusting for patient gender, age, pre-operative functional status, adjuvant therapy, extent of resection, and FT3/FT4 (HR = 3.13, 95% CI: 1.20-8.16, p < 0.019). The C-allele of the DI01 SNP rs2235544 was related to increased circulating free T3/ free T4 ratio in glioma and meningioma patients, indicating greater T4 to T3 conversion.

CONCLUSIONS

SNPs of DIO1 gene (rs2235544) and DIO2 gene (rs12885300) have independent prognostic significance in glioblastoma patients. The C-allele of the DIO1 (rs2235544) is associated with greater T4 to T3 conversion.

Thyroid Hormones and Cancer: A Comprehensive Review of Preclinical and Clinical Studies

Thyroid hormones take major part in normal growth, development and metabolism. Over a century of research has supported a relationship between thyroid hormones and the pathophysiology of various cancer types. In vitro studies as well as research in animal models demonstrated an effect of the thyroid hormones T3 and T4 on cancer proliferation, apoptosis, invasiveness and angiogenesis. Thyroid hormones mediate their effects on the cancer cell through several non-genomic pathways including activation of the plasma membrane receptor integrin αvβ3. Furthermore, cancer development and progression are affected by dysregulation of local bioavailability of thyroid hormones. Case-control and population-based studies provide conflicting results regarding the association between thyroid hormones and cancer. However, a large body of evidence suggests that subclinical and clinical hyperthyroidism increase the risk of several solid malignancies while hypothyroidism may reduce aggressiveness or delay the onset of cancer. Additional support is provided from studies in which dysregulation of the thyroid hormone axis secondary to cancer treatment or thyroid hormone supplementation was shown to affect cancer outcomes. Recent preclinical and clinical studies in various cancer types have further shown promising outcomes following chemical reduction of thyroid hormones or inhibition or their binding to the integrin receptor. This review provides a comprehensive overview of the preclinical and clinical research conducted so far.

Preoperative low tri-iodothyronine concentration is associated with worse health status and shorter five year survival of primary brain tumor patients

BACKGROUND

Low tri-iodothyronine syndrome is associated with worse prognosis of severely ill patients. We investigated the association of thyroid hormone levels with discharge outcomes and 5-year mortality in primary brain tumor patients.

METHODS

From January, 2010 until September, 2011, 230 patients (70% women) before brain tumor surgery were evaluated for cognitive (Mini mental State Examination; MMSE) and functional (Barthel index; BI) status, and thyroid function profile. The Low triiodothyronine syndrome was defined as triiodothyronine concentration below the reference range. Unfavorable discharge outcomes were Glasgow outcome scale score of ≤3. Follow-up continued until November, 2015.

RESULTS

Seventy-four percent of patients had Low triiodothyronine syndrome. Lower total tri-iodothyronine concentrations were associated with lower MMSE (p=.013) and BI (p=.023) scores independent of age, gender and histological diagnosis. Preoperative Low tri-iodothyronine syndrome increased risk for unfavorable discharge outcomes adjusting for age, gender and histological diagnosis (OR=2.944, 95%CI [1.314-6.597], p=.009). In all patients, lower tri-iodothyronine concentrations were associated with greater mortality risk (p≤.038) adjusting for age, gender, extent of resection, adjuvant treatment and histological diagnosis. The Low tri-iodothyronine syndrome was associated with greater 5-year mortality for glioma patients (HR=2.197; 95%CI [1.160-4.163], p=.016) and with shorter survival (249 [260] vs. 352 [399] days; p=.029) of high grade glioma patients independent of age, gender, extent of resection and adjuvant treatment.

CONCLUSIONS

The Low tri-iodothyronine syndrome is common in brain tumor patients and is associated with poor functional and cognitive status, and with worse discharge outcomes. The Low tri-iodothyronine syndrome is associated with shorter survival of glioma patients.

COTI-2, a novel small molecule that is active against multiple human cancer cell lines in vitro and in vivo

Identification of novel anti-cancer compounds with high efficacy and low toxicity is critical in drug development. High-throughput screening and other such strategies are generally resource-intensive. Therefore, in silico computer-aided drug design has gained rapid acceptance and popularity. We employed our proprietary computational platform (CHEMSAS®), which uses a unique combination of traditional and modern pharmacology principles, statistical modeling, medicinal chemistry, and machine-learning technologies to discover and optimize novel compounds that could target various cancers. COTI-2 is a small molecule candidate anti-cancer drug identified using CHEMSAS. This study describes the in vitro and in vivo evaluation of COTI-2. Our data demonstrate that COTI-2 is effective against a diverse group of human cancer cell lines regardless of their tissue of origin or genetic makeup. Most treated cancer cell lines were sensitive to COTI-2 at nanomolar concentrations. When compared to traditional chemotherapy or targeted-therapy agents, COTI-2 showed superior activity against tumor cells, in vitro and in vivo. Despite its potent anti-tumor efficacy, COTI-2 was safe and well-tolerated in vivo. Although the mechanism of action of COTI-2 is still under investigation, preliminary results indicate that it is not a traditional kinase or an Hsp90 inhibitor.

Hormones and immunity in cancer: are thyroid hormones endocrine players in the microglia/glioma cross-talk?

Accumulating evidence indicates that the endocrine and immune systems engage in complex cross-talks in which a prominent role is played by thyroid hormones (THs). The increase of resident vs. monocyte recruited macrophages was shown to be an important effector of the TH 3,3′,5′-Triiodo-L-thyronine (T3)-induced protection against inflammation and a key role of T3 in inhibiting the differentiation of peripheral monocytes into macrophages was observed. Herein, we report on the role of T3 as a modulator of microglia, the specialized macrophages of the central nervous system (CNS). Mounting evidence supports a role of microglia and macrophages in the growth and invasion of malignant glioma. In this respect, we unveil the putative involvement of T3 in the microglia/glioma cell communication. Since THs are known to cross the blood-brain barrier, we suggest that T3 not only exerts a direct modulation of brain cancer cell itself but also indirectly promotes glioma growth through a modulation of microglia. Our observations expand available information on the role of TH system in glioma and its microenvironment and highlight the endocrine modulation of microglia as an important target for future therapeutic development of glioma treatments.

Are Thyroid Hormone and Tumor Cell Proliferation in Human Breast Cancers Positive for HER2 Associated?

Objective. This study investigated whether thyroid hormone (TH) levels are correlated to cell proliferation (Ki67), in euthyroid breast cancer patients. Design and Methods. 86 newly diagnosed breast cancer patients with estrogen receptor (ER) positive tumors, who referred for surgery, were included in the study. Results. FT3, FT4, and TSH were within normal range. No correlation was seen between Ki67 and FT3 (r = -0.17, P = 0.15), FT4 (r = -0.13, P = 0.25), or TSH (r = -0.10, P = 0.39) in all patients studied. However, subgroup analysis showed that, in HER2(+) patients, a negative correlation existed between FT3 levels and Ki67 (r = -0.60 and P = 0.004) but not between Ki67 and FT4 (r = 0.04 and P = 0.85) or TSH (r = -0.23 and P = 0.30). In HER2(-) patients, there was no significant correlation between Ki67 and FT3 (r = -0.06, P = 0.67), FT4 (r = -0.15, P = 0.26), or TSH (r = -0.09, P = 0.49). Phospho-p44/total p44 ERK levels were found to be increased by 2-fold in HER2(+) versus HER2(-) tumors. No difference was detected in phospho-p42/total p42 ERK levels. Conclusions. TH profile is not altered in patients with newly diagnosed breast cancer. However, FT3 levels, even within normal range, are negatively correlated with cell proliferation in HER2(+) breast cancer tumors. This response may be due to the interaction between ERK and TH signaling.

The emerging role of TRα1 in cardiac repair: potential therapeutic implications

Thyroid hormone (TH) is critical for adapting living organisms to environmental stress. Plasma circulating tri-iodothyronine (T3) levels drop in most disease states and are associated with increased oxidative stress. In this context, T3 levels in plasma appear to be an independent determinant for the recovery of cardiac function after myocardial infarction in patients. Thyroid hormone receptor α1 (TRα1) seems to be crucial in this response; TRα1 accumulates to cell nucleus upon activation of stress induced growth kinase signaling. Furthermore, overexpression of nuclear TRα1 in cardiomyocytes can result in pathological or physiological growth (dual action) in absence or presence of its ligand, respectively. Accordingly, inactivation of TRα1 receptor prevents reactive hypertrophy after myocardial infarction and results in heart failure with increased phospholamban (PLB) expression and marked activation of p38MAPK. In line with this evidence, TH is shown to limit ischemia/reperfusion injury and convert pathologic to physiologic growth after myocardial infarction via TRα1 receptor. TRα1 receptor may prove to be a novel pharmacological target for cardiac repair/regeneration therapies.

Thyroid hormone and cardiac repair/regeneration: from Prometheus myth to reality?

Nature's models of repair and (or) regeneration provide substantial evidence that a natural healing process may exist in the heart. The potential for repair and (or) regeneration has been evolutionarily conserved in mammals, and seems to be restricted to the early developmental stages. This window of regeneration is reactivated during the disease state in which fetal gene reprogramming occurs in response to stress. Analogies exist between the damaged and developing heart, indicating that a regulatory network that drives embryonic heart development may control aspects of heart repair and (or) regeneration. In this context, thyroid hormone (TH), which is a critical regulator of the maturation of the myocardium, appears to have a reparative role later in adult life. Changes in TH - thyroid hormone receptor (TR) homeostasis govern the return of the injured myocardium to the fetal phenotype. Accordingly, TH can induce cardiac repair and (or) regeneration by reactivating developmental gene programming. As a proof of concept in humans, TH is found to be an independent determinant of functional recovery and mortality after myocardial infarction. The potential of TH to regenerate and (or) repair the ischemic myocardium is now awaited to be tested in clinical trials.