Tetrac as an anti-angiogenic agent in cancer

Role of Cancer Side Population Stem Cells in Ovarian Cancer Angiogenesis

Ovarian cancer is one of the most common gynecologic malignancies. Recurrence and metastasis often occur after treatment, and it has the highest mortality rate of all gynecological tumors. Cancer stem cells (CSCs) are a small population of cells with the ability of self-renewal, multidirectional differentiation, and infinite proliferation. They have been shown to play an important role in tumor growth, metastasis, drug resistance, and angiogenesis. Ovarian cancer side population (SP) cells, a type of CSC, have been shown to play roles in tumor formation, colony formation, xenograft tumor formation, ascites formation, and tumor metastasis. The rapid progression of tumor angiogenesis is necessary for tumor growth; however, many of the mechanisms driving this process are unclear as is the contribution of CSCs. The aim of this review was to document the current state of knowledge of the molecular mechanism of ovarian cancer stem cells (OCSCs) in regulating tumor angiogenesis.

Angiogenic Activity and Mechanism for Bisphenols on Endothelial Cell and Mouse: Evidence of a Structural-Selective Effect

Increased epidemiological evidence indicates the association of bisphenol exposure with human vascular disorders, while the underlying mechanism has not been clarified. Here, we sought to unveil the potential angiogenic effect and the underlying mechanism of bisphenols with different structural features using endothelial cells treated with an environmentally relevant concentration of bisphenols (range: 1 nM to 10 μM) and a C57BL/6 mouse model fed with doses of 0.002, 0.02, 2, and 20 mg/kg BW/day for 5 weeks. Bisphenol A (BPA) and bisphenol S (BPS) at a 1 nM level significantly increased tube formation by 45.1 and 30.2% and induced the microvessel sprouting, while tube length and microvessel sprouting were significantly inhibited by 37.2 and 55.7% after exposure to tetrabromobisphenol S (TBBPS) at 1 μM, respectively. Mechanistically, TBBPA and TBBPS significantly inhibited the interaction between phosphatidylinositol 3-kinase (PI3K) and thyroid receptor (TR), while BPA and BPS favored the interaction between PI3K and estrogen receptor (ER), resulting in abnormal PI3K signaling with consequent distinct angiogenic activity. BPA- and BPS-induced pro-angiogenic effects and TBBPS showed anti-angiogenic effects due to their distinct disruption on the TR/ER-PI3K pathway. Our work provided new evidence and mechanistic insight on the angiogenic activity of bisphenols and expanded the scope of endocrine disruptors with interference in vascular homeostasis.

αvβ3 Integrin as a Link between the Development of Fibrosis and Thyroid Hormones in Systemic Sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of the skin and internal organs. Key players mediating fibrosis are myofibroblasts (MF) that, following transforming growth factor β (TGFβ) exposure, produce a collagen-rich extracellular matrix (ECM) that induces myofibroblast differentiation. Myofibroblasts express αvβ3 integrin (a membrane receptor for thyroid hormones) and miRNA-21 that promotes deiodinase-type-3 expression (D3), causing the degradation of triiodothyronine (T3) that attenuates fibrosis. We hypothesized that αvβ3 affects the fibrotic processes through its thyroid hormones (THs) binding site. To test this, dermal fibroblasts (DF) were cultured with/without TGFβ and removed with a base, leaving only normal/fibrotic ECMs in wells. Then, DF were cultured on the ECMs with/without tetrac (αvβ3 ligand, T4 antagonist), and evaluated for pro-fibrotic characteristics, αvβ3, miRNA-21, and D3 levels. Blood free-T3 (fT3), miRNA-21 levels, and the modified Rodnan skin score (MRSS) were evaluated in SSc patients. We found that the "fibrotic-ECM" significantly increased the pro-fibrotic characteristics of DF and the levels of miRNA-21, D3, and αvβ3, compared to the "normal-ECM." Tetrac significantly inhibited the effects of the "fibrotic-ECM" on the cells. In accordance with tetrac's effect on D3/miRNA-21, a negative correlation was found between the patients' fT3 to miRNA-21 levels, and to the development of pulmonary arterial hypertension (PAH). We conclude that occupying the THs binding site of αvβ3 may delay the development of fibrosis.

Heteronemin and Tetrac Induce Anti-Proliferation by Blocking EGFR-Mediated Signaling in Colorectal Cancer Cells

Overexpressed EGFR and mutant K-Ras play vital roles in therapeutic resistance in colorectal cancer patients. To search for an effective therapeutic protocol is an urgent task. A secondary metabolite in the sponge Hippospongia sp., Heteronemin, has been shown to induce anti-proliferation in several types of cancers. A thyroxine-deaminated analogue, tetrac, binds to integrin αvβ3 to induce anti-proliferation in different cancers. Heteronemin- and in combination with tetrac-induced antiproliferative effects were evaluated. Tetrac enhanced heteronemin-induced anti-proliferation in HT-29 cells (KRAS WT CRC) and HCT-116 cells (KRAS MT CRC). Heteronemin and tetrac arrested cell cycle in different phases. Combined treatment increased the cell accumulation in sub-G1 and S phases. The combined treatment also induced the inactivation of EGFR signaling and downregulated the phosphorylated ERK1/2 protein in both cell lines. Heteronemin and the combination showed the downregulation of the phosphorylated and total PI3K protein in HT-29 cells (KRAS WT CRC). Results by NanoString technology and RT-qPCR revealed that heteronemin and combined treatment suppressed the expression of EGFR and downstream genes in HCT-116 cells (KRAS MT CRC). Heteronemin or combined treatment downregulated genes associated with cancer progression and decreased cell motility. Heteronemin or the combined treatment suppressed PD-L1 expression in both cancer cell lines. However, only tetrac and the combined treatment inhibited PD-L1 protein accumulation in HT-29 cells (KRAS WT CRC) and HCT-116 cells (KRAS MT CRC), respectively. In summary, heteronemin induced anti-proliferation in colorectal cancer cells by blocking the EGFR-dependent signal transduction pathway. The combined treatment further enhanced the anti-proliferative effect via PD-L1 suppression. It can be an alternative strategy to suppress mutant KRAS resistance for anti-EGFR therapy.

Acute Myeloid Leukemia Mutations and Future Mechanistic Target to Overcome Resistance

OPINION STATEMENT

Cytogenetics and mutation identification in acute myeloid leukemia have allowed for more targeted therapy. Many therapies have been approved by the FDA in the last 3 years including gilteritinib and azacitidine but the overall survival has remained stagnant at 25%. The inability to achieve complete remission was related to the residual leukemic stem cells (LSCs). Thus, the relationship between bone marrow niche and LSCs must be further explored to prevent treatment relapse/resistance. The development of immunotherapy and nanotechnology may play a role in future therapy to achieve the complete remission. Nano-encapsulation of drugs can improve drugs' bioavailability, help drugs evade resistance, and provide combination therapy directly to the cancer cells. Studies indicate targeting surface antigens such as CLL1 and CD123 using chimeric antibody receptor T cells can improve survival outcomes. Finally, new discoveries indicate that inhibiting integrin αvβ3 and acid ceramidase may prove to be efficacious.

Physiological Role and Use of Thyroid Hormone Metabolites - Potential Utility in COVID-19 Patients

Thyroxine and triiodothyronine (T3) are classical thyroid hormones and with relatively well-understood actions. In contrast, the physiological role of thyroid hormone metabolites, also circulating in the blood, is less well characterized. These molecules, namely, reverse triiodothyronine, 3,5-diiodothyronine, 3-iodothyronamine, tetraiodoacetic acid and triiodoacetic acid, mediate both agonistic (thyromimetic) and antagonistic actions additional to the effects of the classical thyroid hormones. Here, we provide an overview of the main factors influencing thyroid hormone action, and then go on to describe the main effects of the metabolites and their potential use in medicine. One section addresses thyroid hormone levels in corona virus disease 19 (COVID-19). It appears that i) the more potently-acting molecules T3 and triiodoacetic acid have shorter half-lives than the less potent antagonists 3-iodothyronamine and tetraiodoacetic acid; ii) reverse T3 and 3,5-diiodothyronine may serve as indicators for metabolic dysregulation and disease, and iii) Nanotetrac may be a promising candidate for treating cancer, and resmetirom and VK2809 for steatohepatitis. Further, the use of L-T3 in the treatment of severely ill COVID-19 patients is critically discussed.

3,5-T2-A Janus-Faced Thyroid Hormone Metabolite Exerts Both Canonical T3-Mimetic Endocrine and Intracrine Hepatic Action

Over the last decades, thyroid hormone metabolites (THMs) received marked attention as it has been demonstrated that they are bioactive compounds. Their concentrations were determined by immunoassay or mass-spectrometry methods. Among those metabolites, 3,5-diiodothyronine (3,5-T2), occurs at low nanomolar concentrations in human serum, but might reach tissue concentrations similar to those of T4 and T3, at least based on data from rodent models. However, the immunoassay-based measurements in human sera revealed remarkable variations depending on antibodies used in the assays and thus need to be interpreted with caution. In clinical experimental approaches in euthyroid volunteers and hypothyroid patients using the immunoassay as the analytical tool no evidence of formation of 3,5-T2 from its putative precursors T4 or T3 was found, nor was any support found for the assumption that 3,5-T2 might represent a direct precursor for serum 3-T1-AM generated by combined deiodination and decarboxylation from 3,5-T2, as previously documented for mouse intestinal mucosa. We hypothesized that lowered endogenous production of 3,5-T2 in patients requiring T4 replacement therapy after thyroidectomy or for treatment of autoimmune thyroid disease, compared to production of 3,5-T2 in individuals with intact thyroid glands might contribute to the discontent seen in a subset of patients with this therapeutic regimen. So far, our observations do not support this assumption. However, the unexpected association between high serum 3,5-T2 and elevated urinary concentrations of metabolites related to coffee consumption requires further studies for an explanation. Elevated 3,5-T2 serum concentrations were found in several situations including impaired renal function, chronic dialysis, sepsis, non-survival in the ICU as well as post-operative atrial fibrillation (POAF) in studies using a monoclonal antibody-based chemoluminescence immunoassay. Pilot analysis of human sera using LC-linear-ion-trap-mass-spectrometry yielded 3,5-T2 concentrations below the limit of quantification in the majority of cases, thus the divergent results of both methods need to be reconciliated by further studies. Although positive anti-steatotic effects have been observed in rodent models, use of 3,5-T2 as a muscle anabolic, slimming or fitness drug, easily obtained without medical prescription, must be advised against, considering its potency in suppressing the HPT axis and causing adverse cardiac side effects. 3,5-T2 escapes regular detection by commercially available clinical routine assays used for thyroid function tests, which may be seriously disrupted in individuals self-administering 3,5-T2 obtained over-the counter or from other sources.

Network Pharmacology-Based Study on the Molecular Biological Mechanism of Action for Compound Kushen Injection in Anti-Cancer Effect

BACKGROUND Compound Kushen injection (CKI) is a traditional Chinese medicine preparation for clinical treatment of cancer pain or treatment of various types of solid tumors. The purpose of this study was to identify the main active compounds from CKI and to investigate its anti-cancer mechanisms via drug target biological network pharmacology construction and prediction. MATERIAL AND METHODS Constituents of CKI were retrieved from Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. Disease targets were collected in the Human Gene (Gene Cards) and Human Mendelian Inheritance (OMIM) databases. "Ingredients-protein targets-pathway" networks were constructed using Cytoscape. STRING database platform to construct enrichment of protein-protein interactions (PPI), related diseases and pathways network. Gene Ontology (GO) biological functions and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway of were performed to investigate by using Bioconductor tool for analysis. RESULTS The results indicated that 60 constituents of absorption, distribution, metabolism, and excretion (ADME) filtration resulted in 33 constituents exhibiting significant correlations with anti-cancer and CKI may target 113 proteins, including IL6, EGFR, CASP3, VEGFA, MYC, and ESR1. GO and KEGG enrichment analysis results show that 129 biological processes and 93 signal pathways associated with cancer. It mainly involves cancers such as prostate cancer, bladder cancer, hepatocellular carcinoma, colorectal cancer, breast cancer, etc. Active ingredients might also induce apoptosis in cancer cells via the p53 and PI3K-Akt signaling pathway mechanism. CONCLUSIONS This study was based on pharmacological networks results for the prediction of the multi-constituent, multi-target, and multi-pathway mechanisms of CKI, which might be a promising potential therapeutic and prevention candidate for anti-cancer. However, based on computer data mining and analysis, this study still needs to be further verified by in vivo/in vitro experiments, and the safety of CKI needs to be evaluated.

Integrin αvβ3-Mediated Effects of Thyroid Hormones on Mesenchymal Stem Cells in Tumor Angiogenesis

Background: Several clinical and experimental studies have implicated thyroid hormones in cancer progression. Cancer-relevant effects, including stimulation of tumor growth and new blood vessel formation by angiogenesis, are thought to be mediated by a nonclassical signaling pathway initiated through integrin αvβ3 expressed on cancer cells and proliferating endothelium. In an earlier study, we established mesenchymal stem cells (MSCs), important contributors to the fibrovascular network of tumors, as new thyroid hormone-dependent targets. Here, we evaluated the effects of the thyroid hormones triiodothyronine (T3) and thyroxine (T4) versus Tetrac, an integrin-specific inhibitor of thyroid hormone action, on MSCs in tumor angiogenesis. Methods: Modulation of the expression and secretion of angiogenesis-relevant factors by thyroid hormones in primary human MSCs and their effect on endothelial cell tube formation were tested in vitro. We further engineered MSCs to express the sodium iodide symporter (NIS) reporter gene under control of a hypoxia-responsive promoter and the vascular endothelial growth factor (VEGF) promoter to test effects on these pathways in vitro and, for VEGF, in vivo in an orthotopic hepatocellular carcinoma (HCC) xenograft mouse model by positron emission tomography imaging. Results: T3 and T4 increased the expression of pro-angiogenic genes in MSCs and NIS-mediated radioiodide uptake in both NIS reporter MSC lines in the presence of HCC cell-conditioned medium. Supernatant from thyroid hormone-treated MSCs significantly enhanced endothelial cell tube formation. Tetrac and/or inhibitors of signaling pathways downstream of the integrin reversed all these effects. Tumoral radioiodide uptake in vivo demonstrated successful recruitment of MSCs to tumors and VEGF promoter-driven NIS expression. Hyperthyroid mice showed an increased radioiodide uptake compared with euthyroid mice, while tracer uptake was markedly reduced in hypothyroid and Tetrac-treated mice. Conclusions: Our data suggest that thyroid hormones influence angiogenic signaling in MSCs via integrin αvβ3 and further substantiate the anti-angiogenic activity of Tetrac in the tumor microenvironment.

Thyroid Hormone Effects on Mesenchymal Stem Cell Biology in the Tumour Microenvironment

Non-classical thyroid hormone signalling via cell surface receptor integrin αvβ3, expressed on most cancer cells and proliferating endothelial cells, has been shown to drive tumour cell proliferation and survival, as well as angiogenesis. Tumours develop within a complex microenvironment that is composed of many different cell types, including mesenchymal stem cells. These multipotent progenitor cells actively home to growing tumours where they differentiate into cancer-associated fibroblast-like cells and blood vessel-stabilising pericytes and thus support the tumour's fibrovascular network. Integrin αvβ3 expression on mesenchymal stem cells makes them susceptible to thyroid hormone stimulation. Indeed, our studies demonstrated - for the first time - that thyroid hormones stimulate the differentiation of mesenchymal stem cells towards a carcinoma-associated fibroblast-/pericyte-like and hypoxia-responsive, pro-angiogenic phenotype, characterised by the secretion of numerous paracrine pro-angiogenic factors, in addition to driving their migration, invasion, and recruitment to the tumour microenvironment in an experimental hepatocellular carcinoma model. The deaminated thyroid hormone metabolite tetrac, a specific inhibitor of thyroid hormone action at the integrin site, reverses these effects. The modulation of mesenchymal stem cell signalling and recruitment by thyroid hormones via integrin αvβ3 adds a further layer to the multifaceted effects of thyroid hormones on tumour progression, with important implications for the management of cancer patients and suggests a novel mechanism for the anti-tumour activity of tetrac.