The nuclear corepressor 1 and the thyroid hormone receptor β suppress breast tumor lymphangiogenesis

Potential use of TG68 - A novel thyromimetic - for the treatment of non-alcoholic fatty liver (NAFLD)-associated hepatocarcinogenesis

Introduction

Several lines of evidence suggest that the thyroid hormone signaling pathway is altered in patients with NAFLD and that pharmacological strategies to target the thyroid hormone/thyroid hormone nuclear receptor axis (TH/THR) in the liver may exert beneficial effects. In this study, we investigated the effect of TG68, a novel THRβ agonist, on rat hepatic fat accumulation and NAFLD-associated hepatocarcinogenesis.

Methods

Male rats given a single dose of diethylnitrosamine (DEN) and fed a high fat diet (HFD) were co-treated with different doses of TG68. Systemic and hepatic metabolic parameters, immunohistochemistry and hepatic gene expression were determined to assess the effect of TG68 on THRβ activation.

Results

Irrespectively of the dose, treatment with TG68 led to a significant reduction in liver weight, hepatic steatosis, circulating triglycerides, cholesterol and blood glucose. Importantly, a short exposure to TG68 caused regression of DEN-induced preneoplastic lesions associated with a differentiation program, as evidenced by a loss of neoplastic markers and reacquisition of markers of differentiated hepatocytes. Finally, while an equimolar dose of the THRβ agonist Resmetirom reduced hepatic fat accumulation, it did not exert any antitumorigenic effect.

Discussion

The use of this novel thyromimetic represents a promising therapeutic strategy for the treatment of NAFLD-associated hepatocarcinogenesis.

mRNA-miRNA networks identify metabolic pathways associated to the anti-tumorigenic effect of thyroid hormone on preneoplastic nodules and hepatocellular carcinoma

Background

Thyroid hormones (THs) inhibit hepatocellular carcinoma (HCC) through different mechanisms. However, whether microRNAs play a role in the antitumorigenic effect of THs remains unknown.

Methods

By next generation sequencing (NGS) we performed a comprehensive comparative miRNomic and transcriptomic analysis of rat hepatic preneoplastic lesions exposed or not to a short-term treatment with triiodothyronine (T3). The expression of the most deregulated miRs was also investigated in rat HCCs, and in human hepatoma cell lines, treated or not with T3.

Results

Among miRs down-regulated in preneoplastic nodules following T3, co-expression networks revealed those targeting thyroid hormone receptor-β (Thrβ) and deiodinase1, and Oxidative Phosphorylation. On the other hand, miRs targeting members of the Nrf2 Oxidative Pathway, Glycolysis, Pentose Phosphate Pathway and Proline biosynthesis – all involved in the metabolic reprogramming displayed by preneoplastic lesions– were up-regulated. Notably, while the expression of most miRs deregulated in preneoplastic lesions was not altered in HCC or in hepatoma cells, miR-182, a miR known to target Dio1 and mitochondrial complexes, was down-deregulated by T3 treatment at all stages of hepatocarcinogenesis and in hepatocarcinoma cell lines. In support to the possible critical role of miR-182 in hepatocarcinogenesis, exogenous expression of this miR significantly impaired the inhibitory effect of T3 on the clonogenic growth capacity of human HCC cells.

Conclusions

This work identified several miRNAs, so far never associated to T3. In addition, the precise definition of the miRNA-mRNA networks elicited by T3 treatment gained in this study may provide a better understanding of the key regulatory events underlying the inhibitory effect of T3 on HCC development. In this context, T3-induced down-regulation of miR-182 appears as a promising tool.

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.

The TSH/Thyroid Hormones Axis and Breast Cancer

Breast cancer, the most prevalent female carcinoma, is characterized by the expression of steroid nuclear receptors in a subset of cases. The most important nuclear receptor with prognostic and therapeutic implications is the Estrogen Receptor (ER), which is expressed in about three out of four breast cancers. The Progesterone Receptor (PR) and the Androgen Receptor (AR) are also commonly expressed. Moreover, non-steroid nuclear receptors, including the vitamin D receptor (VDR) and the thyroid receptors (TRs), are also present in breast cancers and have pathophysiologic implications. Circulating thyroid hormones may influence breast cancer risk and breast cancer cell survival, through ligating their canonical receptors TRα and TRβ but also through additional membrane receptors that are expressed in breast cancer. The expression of TR subtypes and their respective isotypes have diverse effects in breast cancers through co-operation with ER and influence on other cancer-associated pathways. Other components of the TSH/thyroid hormone axis, such as TSH and selenoiodinase enzymes, have putative effects in breast cancer pathophysiology. This paper reviews the pathophysiologic and prognostic implications of the thyroid axis in breast cancer and provides a brief therapeutic perspective.

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.

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.

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

Background: A subpopulation of cancer stem cells (CSCs) with capacity for self-renewal is believed to drive initiation, progression, and relapse of breast tumors. Methods: Since the thyroid hormone receptor β (TRβ) appears to suppress breast tumor growth and metastasis, we have analyzed the possibility that TRβ could affect the CSC population using MCF-7 cells grown under adherent conditions or as mammospheres, as well as inoculation into immunodeficient mice. Results: Treatment of TRβ-expressing MCF-7 cells (MCF7-TRβ cells) with the thyroid hormone triiodothyronine (T3) decreased significantly CD44⁺/CD24^- and ALDH⁺ cell subpopulations, the efficiency of mammosphere formation, the self-renewal capacity of CSCs in limiting dilution assays, the expression of the pluripotency factors in the mammospheres, and tumor initiating capacity in immunodeficient mice, indicating that the hormone reduces the CSC population present within the bulk MCF7-TRβ cultures. T3 also decreased migration and invasion, a hallmark of CSCs. Transcriptome analysis showed downregulation of the estrogen receptor alpha (ERα) and ER-responsive genes by T3. Furthermore, among the T3-repressed genes, there was an enrichment in genes containing binding sites for transcription factors that are key determinants of luminal-type breast cancers and are required for ER binding to chromatin. Conclusion: We demonstrate a novel role of TRβ in the biology of CSCs that may be related to its action as a tumor suppressor in breast cancer.

Lymphatic changes in cancer and drug delivery to the lymphatics in solid tumors

Although many solid tumors use the lymphatic system to metastasize, there are few treatment options that directly target cancer present in the lymphatic system, and those that do are highly invasive, uncomfortable, and/or have limitations. In this review we provide a brief overview of lymphatic function and anatomy, discusses changes that befall the lymphatics in cancer and the mechanisms by which these changes occur, and highlight limitations of lymphatic drug delivery. We then go on to summarize relevant techniques and new research for targeting cancer populations in the lymphatics and enhancing drug delivery intralymphatically, including intralymphatic injections, isolated limb perfusion, passive nano drug delivery systems, and actively targeted nanomedicine.

Neuroevolution as a tool for microarray gene expression pattern identification in cancer research

Microarrays are still one of the major techniques employed to study cancer biology. However, the identification of expression patterns from microarray datasets is still a significant challenge to overcome. In this work, a new approach using Neuroevolution, a machine learning field that combines neural networks and evolutionary computation, provides aid in this challenge by simultaneously classifying microarray data and selecting the subset of more relevant genes. The main algorithm, FS-NEAT, was adapted by the addition of new structural operators designed for this high dimensional data. In addition, a rigorous filtering and preprocessing protocol was employed to select quality microarray datasets for the proposed method, selecting 13 datasets from three different cancer types. The results show that Neuroevolution was able to successfully classify microarray samples when compared with other methods in the literature, while also finding subsets of genes that can be generalized for other algorithms and carry relevant biological information. This approach detected 177 genes, and 82 were validated as already being associated to their respective cancer types and 44 were associated to other types of cancer, becoming potential targets to be explored as cancer biomarkers. Five long non-coding RNAs were also detected, from which four don't have described functions yet. The expression patterns found are intrinsically related to extracellular matrix, exosomes and cell proliferation. The results obtained in this work could aid in unraveling the molecular mechanisms underlying the tumoral process and describe new potential targets to be explored in future works.

Evaluation of transcriptionally regulated genes identifies NCOR1 in hormone receptor negative breast tumors and lung adenocarcinomas as a potential tumor suppressor gene

Regulation of transcription is a key process in cellular homeostasis. It depends on regulators that either repress or stimulate the transcription of genes, therefore controlling different biological functions. The Nuclear Receptor Corepressor 1 (NCOR1) is one of those co-repressors that regulate the transcription by facilitating the recruitment of HDAC1, 2, 3, 4, 5 and 7. In our article, by using an in silico approach, we evaluate the mutational status of NCOR1 in breast and lung tumors. We identified that NORC1 is mutated in more than 3% of breast tumors and lung adenocarcinomas and linked this fact with detrimental outcome in some subtypes, particularly in those that are hormone receptor negative. In addition to these findings, as mutations in this gene are deleterious, we confirmed that high levels of this gene were linked with good prognosis in the same tumor subtypes. Findings in the same direction were identified in lung adenocarcinomas, with mutations associated with detrimental prognosis and high expression with better outcome. In conclusion, hereby we describe the presence and prognostic role of mutations in the NCOR1 gene in hormone receptor negative breast and lung adenocarcinomas, and we also confirm that NCOR1 is a tumor suppressor gene. Further studies should be performed to explore therapeutic mechanisms to restore its function.

CPT1A regulates breast cancer-associated lymphangiogenesis via VEGF signaling

BACKGROUND

Lymphangiogenesis is critical for metastasis of a variety of cancers, including breast cancer. CPT1A (carnitine palmitoyltransferase 1a) has been reported to play a critical role in breast cancer progress. However, the molecular mechanism remains elusive.

METHODS

In order to investigate the role of CPT1A in HDLEC cells, short hairpin RNA approach was utilized to knock down the CPT1A gene expression. We employed transwell and lymphatic vessel formation assay to examine invasion and lymphangiogenesis of HDLEC (Human dermal lymphatic endothelial cells). RT-qPCR and westernblot analyses were used to determine genes expression in HDLEC and breast cancer cells. Finally, we determined the relative rate of acetyl-CoA/CoA in shNC and shCPT1A HDLEC cells by LC-MS approach.

RESULTS

Knockdown of CPT1A in breast cancer cells (MCF-7 and MDA-MB-231) abolished invasion and lymphangiogenesis of HDLEC cells. Mechanistically, CPT1A depletion suppressed the expression of VEGF-C and VEGF-D in MCF-7 and MDA-MB-231 cells. Interestingly, CPT1A knockdown in HDLEC cells exhibited attenuated expression of lymphangiogenic markers (podoplanin, VEGFR-3, VEGF-C, VEGF-D and PROX-1). Consistently, CPT1A -null HDLEC cells displayed compromised invasion and lymphangiogenesis compared with negative control. Further investigation revealed that CPT1A regulated VEGFR3 via acetyl-CoA mediated H3K9ac, which could be abrogated by supplement of acetate.

CONCLUSIONS

In present study, we revealed the mechanism by which CPT1A regulates breast cancer-associated invasion and lymphangiogenesis. Our findings provide insights into CPT1A -promoted breast tumor metastasis and provide rationale for understanding breast cancer metastasis.

Overexpression of modified human TRβ1 suppresses the growth of hepatocarcinoma SK-hep1 cells in vitro and in xenograft models

Association studies suggest that TRβ1 functions as a tumor suppressor. Thyroid hormone receptors (TRs) mediate transcriptional responses through a highly conserved DNA-binding domain (DBD). We previously constructed an artificially modified human TRβ1 (m-TRβ1) via the introduction of a 108-bp exon sequence into the corresponding position of the wild-type human TRβ1 (TRβ1) DBD. Studies confirmed that m-TRβ1 was functional and could inhibit the proliferation of breast cancer MDA-MB-468 cells in vitro. To understand the role of m-TRβ1 in liver tumor development, we adopted a gain-of-function approach by stably expressing TRβ (m-TRβ1 and TRβ1) genes in a human hepatocarcinoma cell line, SK-hep1 (without endogenous TRβ), and then evaluated the effects of the expressed TRβ on cancer cell proliferation, migration, and tumor growth in cell-based studies and xenograft models. In the presence of 3,5,3-l-triiodothyronine (T3), the expression of TRβ in SK-hep1 cells inhibited cancer cell proliferation and impeded tumor cell migration through the up-regulation of 4-1BB, Caspase-3, and Bak gene expression; down-regulation of Bcl-2 gene expression; and activation of the Caspase-3 protein. TRβ expression in SK-hep1 led to less tumor growth in xenograft models. Additionally, the anti-tumor effect of m-TRβ1 was stronger than that of TRβ1. These data indicate that m-TRβ1 can act as a tumor suppressor in hepatocarcinoma and its role was significantly better than that of TRβ1.