Thyroid Hormone Receptor β Inhibits Self-Renewal Capacity of Breast Cancer Stem Cells

Thyroid Hormone Receptors as Tumor Suppressors in Cancer

Accumulated research has revealed the multifaceted roles of thyroid hormone receptors (TRs) as potent tumor suppressors across various cancer types. This review explores the intricate mechanisms underlying TR-mediated tumor suppression, drawing insights from preclinical mouse models and cancer biology. This review examines the tumor-suppressive functions of TRs, particularly TRβ, in various cancers using preclinical models, revealing their ability to inhibit tumor initiation, progression, and metastasis. Molecular mechanisms underlying TR-mediated tumor suppression are discussed, including interactions with oncogenic signaling pathways like PI3K-AKT, JAK-STAT, and transforming growth factor β. Additionally, this paper examines TRs' effect on cancer stem cell activity and differentiation, showcasing their modulation of key cellular processes associated with tumor progression and therapeutic resistance. Insights from preclinical studies underscore the therapeutic potential of targeting TRs to impede cancer stemness and promote cancer cell differentiation, paving the way for precision medicine in cancer treatment and emphasizing the potential of TR-targeted therapies as promising approaches for treating cancers and improving patient outcomes.

The prognostic genes model of breast cancer drug resistance based on single-cell sequencing analysis and transcriptome analysis

Breast cancer (BC) represents a multifaceted malignancy, with escalating incidence and mortality rates annually. Chemotherapy stands as an indispensable approach for treating breast cancer, yet drug resistance poses a formidable challenge. Through transcriptome data analysis, we have identified two sets of genes exhibiting differential expression in this context. Furthermore, we have confirmed the overlap between these genes and those associated with exosomes, which were subsequently validated in cell lines. The investigation screened the identified genes to determine prognostic markers for BC and utilized them to formulate a prognostic model. The disparities in prognosis and immunity between the high- and low-risk groups were validated using the test dataset. We have discerned different BC subtypes based on the expression levels of prognostic genes in BC samples. Variations in prognosis, immunity, and drug sensitivity among distinct subtypes were examined. Leveraging data from single-cell sequencing and prognostic gene expression, the AUCell algorithm was employed to score individual cell clusters and analyze the pathways implicated in high-scoring groups. Prognostic genes (CCT4, CXCL13, MTDH, PSMD2, and RAB27A) were subsewoquently validated using RT-qPCR. Consequently, we have established a model for predicting prognosis in breast cancer that hinges on drug resistance and ERGs. Furthermore, we have evaluated the prognostic value of this model. The genes identified as prognostic markers can now serve as a reference for precise treatment of this condition.

The thyroid hormone enhances mouse embryonic fibroblasts reprogramming to pluripotent stem cells: role of the nuclear receptor corepressor 1

Introduction

Pluripotent stem cells can be generated from somatic cells by the Yamanaka factors Oct4, Sox2, Klf4 and c-Myc.

Methods

Mouse embryonic fibroblasts (MEFs) were transduced with the Yamanaka factors and generation of induced pluripotent stem cells (iPSCs) was assessed by formation of alkaline phosphatase positive colonies, pluripotency gene expression and embryod bodies formation.

Results

The thyroid hormone triiodothyronine (T3) enhances MEFs reprogramming. T3-induced iPSCs resemble embryonic stem cells in terms of the expression profile and DNA methylation pattern of pluripotency genes, and of their potential for embryod body formation and differentiation into the three major germ layers. T3 induces reprogramming even though it increases expression of the cyclin kinase inhibitors p21 and p27, which are known to oppose acquisition of pluripotency. The actions of T3 on reprogramming are mainly mediated by the thyroid hormone receptor beta and T3 can enhance iPSC generation in the absence of c-Myc. The hormone cannot replace Oct4 on reprogramming, but in the presence of T3 is possible to obtain iPSCs, although with low efficiency, without exogenous Klf4. Furthermore, depletion of the corepressor NCoR (or Nuclear Receptor Corepressor 1) reduces MEFs reprogramming in the absence of the hormone and strongly decreases iPSC generation by T3 and also by 9cis-retinoic acid, a well-known inducer of reprogramming. NCoR depletion also markedly antagonizes induction of pluripotency gene expression by both ligands.

Conclusions

Inclusion of T3 on reprogramming strategies has a potential use in enhancing the generation of functional iPSCs for studies of cell plasticity, disease and regenerative medicine.

TRβ Agonism Induces Tumor Suppression and Enhances Drug Efficacy in Anaplastic Thyroid Cancer in Female Mice

Thyroid hormone receptor beta (TRβ) is a recognized tumor suppressor in numerous solid cancers. The molecular signaling of TRβ has been elucidated in several cancer types through re-expression models. Remarkably, the potential impact of selective activation of endogenous TRβ on tumor progression remains largely unexplored. We used cell-based and in vivo assays to evaluate the effects of the TRβ agonist sobetirome (GC-1) on a particularly aggressive and dedifferentiated cancer, anaplastic thyroid cancer (ATC). Here we report that GC-1 reduced the tumorigenic phenotype, decreased cancer stem-like cell populations, and induced redifferentiation of the ATC cell lines with different mutational backgrounds. Of note, this selective activation of TRβ amplified the effects of therapeutic agents in blunting the aggressive cell phenotype and stem cell growth. In xenograft assays, GC-1 alone inhibited tumor growth and was as effective as the kinase inhibitor, sorafenib. These results indicate that selective activation of TRβ not only induces a tumor suppression program de novo but enhances the effectiveness of anticancer agents, revealing potential novel combination therapies for ATC and other aggressive solid tumors.

Triiodothyronine lowers the potential of colorectal cancer stem cells in vitro

Cancer stem cells (CSCs) play a key role in the development and progression of colorectal cancer (CRC), but the influence of triiodothyronine (T3) on the biological regulation of CSCs remains unclear. In the present study, it was reported that T3 exerts significant impact on CSCs of two CRC cell lines cultured in the form of colonospheres. It was observed that the incubation of colonospheres with T3 decreased the viability, proliferative and spherogenic potential of cancer cells (P<0.05). In addition, increased apoptotic rate of CRC cells treated with T3 was revealed. Furthermore, T3‑treated colonospheres were more likely to move into silenced pool in G0/G1 phase of the cell cycle. The smaller sizes of colonospheres observed after the treatment with T3 confirmed this conclusion. T3 could lower the proportion of primitive cells which supply the pool of proliferating cells within spheres. Thyroid receptors THRα1 and THRβ1 and two deiodinases (DIO2 and DIO3) were affected by T3 in manner depended on clinical stage of cancer and CRC cell line used for analysis. In summary, the present study uncovered a novel function of thyroid hormones signaling in the regulation of the CSCs of CRC, and these findings may be useful for developing novel therapies by targeting thyroid hormone functions in CRC cells.

Thyroid Hormone Receptor β Knockdown Reduces Suppression of Progestins by Activating the mTOR Pathway in Endometrial Cancer Cells

Progestin resistance is a major obstacle to conservative therapy in patients with endometrial cancer (EC) and endometrial atypical hyperplasia (EAH). However, the related inducing factor is yet unclear. In this study, thyroid hormone and its receptor α (TRα) and β (TRβ) of patients were assayed. THRB-silenced RL95-2 and KLE EC cells were cultured to investigate the response of progestins. Transcriptomics and Western blotting were performed to investigate the changes in signaling pathways. We found that THRB, rather than THRA, knockdown promoted the viability and motilities of RL95-2 cells but not KLE cells. The suppressive effect of progestins on cell growth and motility significantly decreased in THRB-silenced RL95-2 cells. Multiple proliferation-related signaling pathways were enriched, and the activities of mammalian targets of rapamycin (mTOR)/4e-binding protein 1 (4EBP1)/eukaryotic translation initiation factor 4G (eIF4G) rather than phosphorylated protein kinase B (Akt) were remarkably boosted. Progestin treatment enhanced the effects, and the augmentation was partially abated on supplementation with T3. In THRB-knockdown KLE cells, the progestins-activated partial signaling pathway expression (either mTOR or eIF4G), and supplementation with T3 did not induce noticeable alterations. The serum levels of triiodothyronine (T3) were significantly lower in patients with EC compared with healthy women. A strong expression of TRβ was observed in most patients with EC and EAH sensitive to progestin treatment. In contrast, TRα positive expression was detected in less than half of the patients sensitive to progestin therapy. In conclusion, THRB knockdown enhanced the viability and motility of type I EC cells and attenuated the suppressive effects of progestins by activating the mTOR-4EBP1/eIF4G pathway. Lower expression of THRB is likely correlated with progesterone resistance.

Case report: Lymph node metastases of breast cancer and thyroid cancer encountered in axilla

Occurrences of breast cancer and thyroid cancer metachronously or synchronously are common for women, but axillary lymph node metastasis from both cancers is rarely seen. We report a patient who had two metastatic lymph nodes from papillary thyroid carcinoma after axillary lymph node dissection with mastectomy. Papillary thyroid carcinoma diagnosis was ensured after thyroidectomy. A literature review revealed that even the co-occurrence of breast cancer and thyroid cancer is not rare, but the etiology behind this phenomenon is not elucidated well. Genetic disorders, thyroid dysfunction, and hormone receptors may be relevant. Considering the rareness of axillary lymph node metastasis of thyroid cancer, adjuvant therapy and surgery treatment for this kind of case should be considered elaborately.

Thyroid hormones act as modulators of inflammation through their nuclear receptors

Reciprocal crosstalk between endocrine and immune systems has been well-documented both in physiological and pathological conditions, although the connection between the immune system and thyroid hormones (THs) remains largely unclear. Inflammation and infection are two important processes modulated by the immune system, which have profound effects on both central and peripheral THs metabolism. Conversely, optimal levels of THs are necessary for the maintenance of immune function and response. Although some effects of THs are mediated by their binding to cell membrane integrin receptors, triggering a non-genomic response, most of the actions of these hormones involve their binding to specific nuclear thyroid receptors (TRs), which generate a genomic response by modulating the activity of a great variety of transcription factors. In this special review on THs role in health and disease, we highlight the relevance of these hormones in the molecular mechanisms linked to inflammation upon their binding to specific nuclear receptors. In particular, we focus on THs effects on different signaling pathways involved in the inflammation associated with various infectious and/or pathological processes, emphasizing those mediated by NF-kB, p38MAPK and JAK/STAT. The findings showed in this review suggest new opportunities to improve current therapeutic strategies for the treatment of inflammation associated with several infections and/or diseases, such as cancer, sepsis or Covid-19 infection.

Hormonal Crosstalk Between Thyroid and Breast Cancer

Differentiated thyroid cancer and breast cancer account for a significant portion of endocrine-related malignancies and predominately affect women. As hormonally responsive tissues, the breast and thyroid share endocrine signaling. Breast cells are responsive to thyroid hormone signaling and are affected by altered thyroid hormone levels. Thyroid cells are responsive to sex hormones, particularly estrogen, and undergo protumorigenic processes upon estrogen stimulation. Thyroid and sex hormones also display significant transcriptional crosstalk that influences oncogenesis and treatment sensitivity. Obesity-related adipocyte alterations-adipocyte estrogen production, inflammation, feeding hormone dysregulation, and metabolic syndromes-promote hormonal alterations in breast and thyroid tissues. Environmental toxicants disrupt endocrine systems, including breast and thyroid homeostasis, and influence pathologic processes in both organs through hormone mimetic action. In this brief review, we discuss the hormonal connections between the breast and thyroid and perspectives on hormonal therapies for breast and thyroid cancer. Future research efforts should acknowledge and further explore the hormonal crosstalk of these tissues in an effort to further understand the prevalence of thyroid and breast cancer in women and to identify potential therapeutic options.

Thyroid receptor β might be responsible for breast cancer associated with Hashimoto's thyroiditis: a new insight into pathogenesis

Breast cancer is the most common cancer affecting females worldwide. Often it is observed that women suffering from Hashimoto's thyroiditis exhibit a greater propensity towards development of breast cancer. The exact mechanism for the same is unknown. However, multiple experimental evidences suggest a significant role of thyroid receptor β (TR-β) in regulating cell growth and proliferation and thus play a potent role as a tumor suppressor in several cancers, including breast cancer. Thyroid receptor β shows anti-proliferative action through mediators like β-catenin, RUNX2, PI3K/AKT, and cyclin regulation. The present review explores the link between these pathways and how they may be dysregulated due to Hashimoto's thyroiditis. Further, we propose a new mechanism for cancer prognosis associated with Hashimoto's thyroiditis, which may lead to the development of TR-β targeting as a novel therapeutic approach.

Selective thyroid hormone receptor beta agonist, GC-1, is capable to reduce growth of colorectal tumor in syngeneic mouse models

OBJECTIVE

The effect of thyroid hormone (TH) on cancers was proposed more than 100 years ago; however, conclusions are conflicting. THs are precisely regulated at tissue and cellular levels. It seems that this regulation is altered in cancers. Thyroid hormone receptor beta (TRβ) has anti-proliferative and tumor-suppressive effects in many cancer cells. Therefore, we decided to investigate thyroid hormone receptor beta (THRB) expression and activation by the selective agonist, GC-1, on tumor growth in a syngeneic mouse model of colorectal cancer (CRC) and colon cell lines.

METHODS

In vitro cell viability assay using MTT analysis, cell cycle analysis by PI staining, and FACS analysis were performed. In vivo tumor growth measurements were carried out by caliper and [¹⁸F] Fluoro-2-deoxy-2-D-glucose (FDG) - PET imaging. Gene expressions were determined using quantitative-PCR.

RESULTS

Some concentrations of GC-1 had a marked negative effect on the cell viability of colorectal cell lines. Cell cycle analysis showed that the anti-proliferative effect of GC-1 may not result from cell cycle arrest or apoptosis. Tumor growth analysis in mice harboring colorectal tumor showed that GC-1 treatment for 8 d profoundly inhibited tumor growth and ¹⁸FDG uptake. THRB expression was decreased in mice tumor; however, it was upregulated following GC-1 administration.

CONCLUSIONS

Our results showed that specific activation of TRβ by GC-1 had negative effect on tumor growth and restored its gene expression in tumors of CRC mice model.

Regulation of cancer stem cell activity by thyroid hormone receptor β

Increasing numbers of cancer stem cell markers have been recently identified. It is not known, however, whether a member of the nuclear receptor superfamily, thyroid hormone receptor β (TRβ), can function to regulate cancer stem cell (CSC) activity. Using anaplastic thyroid cancer cells (ATC) as a model, we highlight the role of TRβ in CSC activity. ATC is one of the most aggressive solid cancers in humans and is resistant to currently available therapeutics. Recent studies provide evidence that CSC activity underlies aggressiveness and therapeutic resistance of ATC. Here we show that TRβ inhibits CSC activity by suppressing tumor-sphere formation of human ATC cells and their tumor-initiating capacity. TRβ suppresses the expression of CSC regulators, including ALDH, KLF2, SOX2, b-catenin, and ABCG2, in ATC cell-induced xenograft tumors. Single-cell transcriptomic analysis shows that TRβ reduces CSC population in ATC-induced xenograft tumors. Analysis of The Cancer Genome Atlas (TCGA) database demonstrates that the inhibition of CSC capacity by TRβ contributes to favorable clinical outcomes in human cancer. Our studies show that TRβ is a newly identified transcription regulator that acts to suppress CSC activity and that TRβ could be considered as a molecular target for therapeutic intervention of ATC.

Common tumor-suppressive signaling of thyroid hormone receptor beta in breast and thyroid cancer cells

The thyroid hormone receptor beta (TRβ) is a tumor suppressor in multiple types of solid tumors, most prominently in breast and thyroid cancer. An increased understanding of the molecular mechanisms by which TRβ abrogates tumorigenesis will aid in understanding the core tumor-suppressive functions of TRβ. Here, we restored TRβ expression in the MDA-MB-468 basal-like breast cancer cell line and perform RNA-sequencing to determine the TRβ-mediated changes in gene expression and associated signaling pathways. The TRβ expressing MDA-MB-468 cells exhibit a more epithelial character as determined by principle component analysis-based iterative PAM50 subtyping score and through reduced expression of mesenchymal cytokeratins. The epithelial to mesenchymal transition pathway is also significantly reduced. The MDA-MB-468 data set was further compared with RNA sequencing results from TRβ expressing thyroid cancer cell line SW1736 to determine which genes are TRβ correspondingly regulated across both cell types. Several pathways including lipid metabolism and chromatin remodeling processes were observed to be altered in the shared gene set. These data provide novel insights into the molecular mechanisms by which TRβ suppresses breast tumorigenesis.

Endocrine regulation of cancer stem cell compartments in breast tumors

Cancer cells within breast tumors exist within a hierarchy in which only a small and rare subset of cells is able to regenerate growths with the heterogeneity of the original tumor. These highly malignant cancer cells, which behave like stem cells for new cancers and are called "cancer stem cells" or CSCs, have also been shown to possess increased resistance to therapeutics, and represent the root cause underlying therapy failures, persistence of residual disease, and relapse. As >90% of cancer deaths are due to refractory tumors, identification of critical molecular drivers of the CSC-state would reveal vulnerabilities that can be leveraged in designing therapeutics that eradicate advanced disease and improve patient survival outcomes. An expanding and complex body of work has now described the exquisite susceptibility of CSC pools to the regulatory influences of local and systemic hormones. Indeed, breast CSCs express a plethora of hormonal receptors, which funnel hormonal influences over every aspect of breast neoplasia - be it tumor onset, growth, survival, invasion, metastasis, or therapy resistance - via directly impacting CSC behavior. This article is intended to shed light on this active area of investigation by attempting to provide a systematic and comprehensive overview of the available evidence directly linking hormones to breast CSC biology.

Thyroid Hormone Receptor Beta as Tumor Suppressor: Untapped Potential in Treatment and Diagnostics in Solid Tumors

There is compelling evidence that the nuclear receptor TRβ, a member of the thyroid hormone receptor (TR) family, is a tumor suppressor in thyroid, breast, and other solid tumors. Cell-based and animal studies reveal that the liganded TRβ induces apoptosis, reduces an aggressive phenotype, decreases stem cell populations, and slows tumor growth through modulation of a complex interplay of transcriptional networks. TRβ-driven tumor suppressive transcriptomic signatures include repression of known drivers of proliferation such as PI3K/Akt pathway, activation of novel signaling such as JAK1/STAT1, and metabolic reprogramming in both thyroid and breast cancers. The presence of TRβ is also correlated with a positive prognosis and response to therapeutics in BRCA+ and triple-negative breast cancers, respectively. Ligand activation of TRβ enhances sensitivity to chemotherapeutics. TRβ co-regulators and bromodomain-containing chromatin remodeling proteins are emergent therapeutic targets. This review considers TRβ as a potential biomolecular diagnostic and therapeutic target.

Thyroid Hormone Receptor Beta Inhibits PI3K-Akt-mTOR Signaling Axis in Anaplastic Thyroid Cancer via Genomic Mechanisms

Thyroid cancer is the most common endocrine malignancy, and the global incidence has increased rapidly over the past few decades. Anaplastic thyroid cancer (ATC) is highly aggressive, dedifferentiated, and patients have a median survival of fewer than 6 months. Oncogenic alterations in ATC include aberrant phosphoinositide 3 kinase (PI3K) signaling through receptor tyrosine kinase (RTK) amplification, loss of phosphoinositide phosphatase expression and function, and protein kinase B (Akt) amplification. Furthermore, the loss of expression of the tumor suppressor thyroid hormone receptor beta (TRβ) is strongly associated with ATC. TRβ is known to suppress PI3K in follicular thyroid cancer and breast cancer by binding to the PI3K regulatory subunit p85α. However, the role of TRβ in suppressing PI3K signaling in ATC is not completely delineated. Here we report that TRβ indeed suppresses PI3K signaling in ATC cell lines through unreported genomic mechanisms, including a decrease in RTK expression and an increase in phosphoinositide and Akt phosphatase expression. Furthermore, the reintroduction and activation of TRβ in ATC cell lines enables an increase in the efficacy of the competitive PI3K inhibitors LY294002 and buparlisib on cell viability, migration, and suppression of PI3K signaling. These findings not only uncover additional tumor suppressor mechanisms of TRβ but shed light on the implication of TRβ status and activation on inhibitor efficacy in ATC tumors.

Nuclear receptors: Lipid and hormone sensors with essential roles in the control of cancer development

Nuclear receptors (NRs) are a superfamily of ligand-activated transcription factors that act as biological sensors and use a combination of mechanisms to modulate positively and negatively gene expression in a spatial and temporal manner. The highly orchestrated biological actions of several NRs influence the proliferation, differentiation, and apoptosis of many different cell types. Synthetic ligands for several NRs have been the focus of extensive drug discovery efforts for cancer intervention. This review summarizes the roles in tumour growth and metastasis of several relevant NR family members, namely androgen receptor (AR), estrogen receptor (ER), glucocorticoid receptor (GR), thyroid hormone receptor (TR), retinoic acid receptors (RARs), retinoid X receptors (RXRs), peroxisome proliferator-activated receptors (PPARs), and liver X receptors (LXRs). These studies are key to develop improved therapeutic agents based on novel modes of action with reduced side effects and overcoming resistance.

Stress erythropoiesis in atherogenic mice

Bone marrow erythropoiesis is mainly homeostatic and a demand of oxygen in tissues activates stress erythropoiesis in the spleen. Here, we show an increase in the number of circulating erythrocytes in apolipoprotein E-/- mice fed a Western high-fat diet, with similar number of circulating leukocytes and CD41+ events (platelets). Atherogenic conditions increase spleen erythropoiesis with no variations of this cell lineage in the bone marrow. Spleens from atherogenic mice show augmented number of late-stage erythroblasts and biased differentiation of progenitor cells towards the erythroid cell lineage, with an increase of CD71+CD41CD34-CD117+Sca1-Lin- cells (erythroid-primed megakaryocyte-erythroid progenitors), which is consistent with the way in which atherogenesis modifies the expression of pro-erythroid and pro-megakaryocytic genes in megakaryocyte-erythroid progenitors. These data explain the transiently improved response to an acute severe hemolytic anemia insult found in atherogenic mice in comparison to control mice, as well as the higher burst-forming unit-erythroid and colony forming unit-erythroid capacity of splenocytes from atherogenic mice. In conclusion, our work demonstrates that, along with the well stablished enhancement of monocytosis during atherogenesis, stress erythropoiesis in apolipoprotein E-/- mice fed a Western high fat diet results in increased numbers of circulating red blood cells.

Thyroid Hormone Receptor Beta Induces a Tumor-Suppressive Program in Anaplastic Thyroid Cancer

The thyroid hormone receptor beta (TRβ), a key regulator of cellular growth and differentiation, is frequently dysregulated in cancers. Diminished expression of TRβ is noted in thyroid, breast, and other solid tumors and is correlated with more aggressive disease. Restoration of TRβ levels decreased tumor growth supporting the concept that TRβ could function as a tumor suppressor. Yet, the TRβ tumor suppression transcriptome is not well delineated and the impact of TRβ is unknown in aggressive anaplastic thyroid cancer (ATC). Here, we establish that restoration of TRβ expression in the human ATC cell line SW1736 (SW-TRβ) reduces the aggressive phenotype, decreases cancer stem cell populations and induces cell death in a T3-dependent manner. Transcriptomic analysis of SW-TRβ cells via RNA sequencing revealed distinctive expression patterns induced by ligand-bound TRβ and revealed novel molecular signaling pathways. Of note, liganded TRβ repressed multiple nodes in the PI3K/AKT pathway, induced expression of thyroid differentiation markers, and promoted proapoptotic pathways. Our results further revealed the JAK1-STAT1 pathway as a novel, T3-mediated, antitumorigenic pathway that can be activated in additional ATC lines. These findings elucidate a TRβ-driven tumor suppression transcriptomic signature, highlight unexplored therapeutic options for ATC, and support TRβ activation as a promising therapeutic option in cancers. IMPLICATIONS: TRβ-T3 induced a less aggressive phenotype and tumor suppression program in anaplastic thyroid cancer cells revealing new potential therapeutic targets.

Cytoplasmic and Nuclear Forms of Thyroid Hormone Receptor β1 Are Inversely Associated with Survival in Primary Breast Cancer

The aim of this study was to investigate the expression of thyroid hormone receptor β1 (THRβ1) by immunohistochemistry in breast cancer (BC) tissues and to correlate the results with clinico-biological parameters. In a well-characterized cohort of 274 primary BC patients, THRβ1 was widely expressed with a predominant nuclear location, although cytoplasmic staining was also frequently observed. Both nuclear and cytoplasmic THRβ1 were correlated with high-risk BC markers such as human epidermal growth factor receptor 2 (HER2), Ki67 (also known as MKI67), prominin-1 (CD133), and N-cadherin. Overall survival analysis demonstrated that cytoplasmic THRβ1 was correlated with favourable survival (p = 0.015), whereas nuclear THRβ1 had a statistically significant correlation with poor outcome (p = 0.038). Interestingly, in our cohort, nuclear and cytoplasmic THRβ1 appeared to be independent markers either for poor (p = 0.0004) or for good (p = 0.048) prognosis, respectively. Altogether, these data indicate that the subcellular expression of THRβ1 may play an important role in oncogenesis. Moreover, the expression of nuclear THRβ1 is a negative outcome marker, which may help to identify high-risk BC subgroups.