Leptin-derived peptides block leptin-induced proliferation by reducing expression of pro-inflammatory genes in hepatocellular carcinoma cells.

The obesity-regulated gene, leptin, is essential for diet. Leptin resistance causes obesity and related diseases. Certain types of diet are able to decrease leptin resistance. However, leptin has been shown to be correlated with inflammation and stimulate proliferation of various cancers. Two synthetic leptin derivatives (mimetics), OB3 and [D-Leu-4]-OB3, show more effective than leptin in reducing obesity and diabetes in mouse models. OB3 inhibits leptin-induced proliferation in ovarian cancer cells. However, effects of these mimetics in hepatocellular carcinoma (HCC) have not been investigated. In the present study, we examined the effects of OB3 and [D-Leu-4]-OB3 on cell proliferation and gene expressions in human HCC cell cultures. In contrast to what was reported for leptin, OB3 and [D-Leu-4]-OB3 reduced cell proliferation in hepatomas. Both OB3 and [D-Leu-4]-OB3 stimulated expression of pro-apoptotic genes. Both compounds also inhibited expressions of pro-inflammatory, proliferative and metastatic genes and PD-L1 expression. In combination with leptin, OB3 inhibited leptin-induced cell proliferation and expressions of pro-inflammation-, and proliferation-related genes. Furthermore, the OB3 peptide inhibited phosphoinositide 3-kinase (PI3K) activation which is essential for leptin-induced proliferation in HCC. These results indicate that OB3 and [D-Leu-4]-OB3 may have the potential to reduce leptin-related inflammation and proliferation in HCC cells.

Action of Reverse T3 on Cancer Cells.

Background: Reverse T3 (rT3; 3,3',5'-triiodo-L-thyronine) is widely regarded as an inactive naturally occurring analog of thyroid hormone. rT3 is known to bind to the thyroid hormone analog receptor on plasma membrane integrin αvß3. This integrin is generously expressed by tumor cells and is the initiation site for the stimulation by L-thyroxine (T4) at physiological free concentrations on cancer cell proliferation. Results: In the present studies, we show that rT3 caused increases of proliferation in vitro of 50% to 80% (P < 0.05-0.001) of human breast cancer and glioblastoma cells. Conclusion: rT3 may be a host factor supporting cancer growth.

Corrigendum: Tetrac and NDAT Induce Anti-proliferation via Integrin αvß3 in Colorectal Cancers With Different K-RAS Status.

[This corrects the article DOI: 10.3389/fendo.2019.00130.].

Tetrac and NDAT Induce Anti-proliferation via Integrin αvß3 in Colorectal Cancers With Different K-RAS Status.

Colorectal cancer is a serious medical problem in Taiwan. New, effective therapeutic approaches are needed. The selection of promising anticancer drugs and the transition from pre-clinical investigations to clinical trials are often challenging. The deaminated thyroid hormone analog (tetraiodothyroacetic acid, tetrac) and its nanoparticulate analog (NDAT) have been shown to have anti-proliferative activity in vitro and in xenograft model of different neoplasms, including colorectal cancers. However, mechanisms involved in tetrac- and NDAT-induced anti-proliferation in colorectal cancers are incompletely understood. We have investigated possible mechanisms of tetrac and NDAT action in colorectal cancer cells, using a perfusion bellows cell culture system that allows efficient, large-scale screening for mechanisms of drug actions on tumor cells. Although integrin αvß3 in K-RAS wild type colorectal cancer HT-29 cells was far less than that in K-RAS mutant HCT116 cells, HT-29 was more sensitive to both tetrac and NDAT. Results also indicate that both tetrac and NDAT bind to tumor cell surface integrin αvß3, and the agents may have different mechanisms of anti-proliferation in colorectal cancer cells. K-RAS status appears to play an important role in drug resistance that may be encountered in treatment with this drug combination.

Heteronemin Induces Anti-Proliferation in Cholangiocarcinoma Cells via Inhibiting TGF-ß Pathway.

A marine sesterterpenoid-type natural product, heteronemin, retains anticancer effects. In the current study, we investigate the antitumor mechanism of heteronemin in cholangiocarcinoma cells and further explore its molecular targets. Initially, heteronemin exhibited potent cytotoxic effects against cholangiocarcinoma HuccT1 and SSP-25 cells. In vitro, heteronemin altered the abilities of cell adhesion and cell migration in HuccT1 and SSP-25 cell lines. It repressed messenger ribonucleic acid (mRNA) expression levels of transforming growth factor (TGF)-ß, mothers against decapentaplegic homolog (SMAD) and Myc, whose protein products play important roles in regulating cell growth, angiogenesis, and metastasis. In addition, heteronemin altered several signaling pathways. The results indicate that heteronemin was able to modulate cell adhesion, the expression of extracellular matrix (ECM) receptors, the TGF-ß pathway, cell motility, the membrane integration, metastasis response, matrix metalloproteinase (MMP) remodeling, the regulation of metabolism, sprouting angiogenesis, transcription factors, and vasculogenesis in cholangiocarcinoma cell lines. The results also suggest that it activated multiple signal transduction pathways to induce an anti-proliferation effect and anti-metastasis in cholangiocarcinoma. In conclusion, heteronemin may be used as a potential medicine for anticancer therapy.

Bioactivity of Thyroid Hormone Analogs at Cancer Cells.

In the context of genomic thyroid hormone actions in normal (noncancer) cells that involve primary interactions with nuclear thyroid hormone receptors (TRs), L-thyroxine (T4), and 3,3',5'-triiodo-L-thyronine (reverse T3, rT3) have little bioactivity. In terms of TRs, T4 is a prohormone from which the active nuclear ligand, 3,5,3'-triido-L-thyronine (T3), is generated by deiodination. Deaminated T4 and T3 metabolites have different genomic effects: tetraiodothyroacetic acid (tetrac) is a low grade thyromimetic derivative of T4, whereas triiodothyroacetic acid (triac), the acetic acid metabolite of T3, has substantial thyromimetic activity. In cancer cells, the cell surface receptor for thyroid hormone on integrin αvß3 mediates non-genomic actions of thyroid hormone analogs. The integrin is expressed in large measure by cancer cells and dividing endothelial cells and has a substantially different panel of responses to thyroid hormone analogs. At αvß3, T4 is a potent proliferative, anti-apoptotic and pro-angiogenic hormone and is the primary ligand. rT3 may also be proliferative at this site. In contrast, tetrac and triac are antagonists of T4 at αvß3, but also have anticancer properties at this site that are independent of their effects on the binding of T4.

Inhibitory Effect of Anoectochilus formosanus Extract on Hyperglycemia-Related PD-L1 Expression and Cancer Proliferation.

Traditional herb medicine, golden thread (Anoectochilus formosanus Hayata) has been used to treat various diseases. Hyperglycemia induces generation of reactive oxygen species (ROS) and enhancement of oxidative stress which are risk factors for cancer progression and metastasis. In this study, we evaluated hypoglycemic effect of A. formosanus extracts (AFEs) in an inducible hyperglycemia animal model and its capacity of free-radical scavenging to establish hyperglycemia-related carcinogenesis. AFE reduced blood glucose in hyperglycemic mice while there was no change in control group. The incremental area under blood glucose response curve was decreased significantly in hyperglycemic mice treated with AFE in a dose-dependent manner. AFE and metformin at the same administrated dose of 50 mg/kg showed similar effect on intraperitoneal glucose tolerance test in hyperglycemic mice. Free-radical scavenger capacity of AFE was concentration dependent and 200 µg/ml of AFE was able to reduce more than 41% of the free radical. Treatment of cancer cells with AFE inhibited constitutive PD-L1 expression and its protein accumulation. It also induced expression of pro-apoptotic genes but inhibited proliferative and metastatic genes. In addition, it induced anti-proliferation in cancer cells. The results suggested that AFE not only reduced blood glucose concentration as metformin but also showed its potential use in cancer immune chemoprevention/therapy via hypoglycemic effect, ROS scavenging and PD-L1 suppression.

Resveratrol inhibits human leiomyoma cell proliferation via crosstalk between integrin αvß3 and IGF-1R.

Leiomyomas (myomas) are the most common benign smooth muscle cell tumor of the myometrium. Resveratrol, a stilbene, has been used as an anti-inflammatory and antitumor agent. In the current study, we investigated the inhibitory effect of resveratrol on the proliferation of primary human myoma cell cultures. Resveratrol arrested cell proliferation via integrin αvß3. It also inhibited integrin αvß3 expression and protein accumulation. Concurrently, constitutive AKT phosphorylation in myoma cells was inhibited by resveratrol. Expressions of proapoptotic genes, such as cyclooxygenase (COX)-2, p21 and CDKN2, were induced by resveratrol in myoma cells. On the other hand, expressions of proliferative (anti-apoptotic) genes were either inhibited, as in BCL2, or unchanged, as in cyclin D1 and proliferating cell nuclear antigen (PCNA). The accumulation of insulin-like growth factor (IGF)-1 receptor (IGF-1R) was inhibited by resveratrol in primary myoma cells. IGF-1-induced cell proliferation was inhibited by co-incubation with resveratrol. Therefore, growth modulation of myoma cells occurs via mechanisms dependent on cross-talk between integrin αvß3 and IGF-1R. Our findings suggest that resveratrol can be considered an alternative therapeutic agent for myomas.

Therapeutic applications of resveratrol and its derivatives on periodontitis.

Periodontitis is an inflammatory disease of the supporting tissues of the teeth induced by periodontopathic bacteria that results in the progressive destruction of periodontal tissues. Treatment of periodontitis is painful and time-consuming. Recently, herbal medicines have been considered for use in treating inflammation-related diseases, including periodontitis. Resveratrol and its derivative 2,3,5,4'-tetrahydroxystilbene-2-O-ß-glucoside (THSG), a polyphenol extracted from Polygonum multiflorum, have anti-inflammatory properties and other medical benefits. Here, we highlight the importance of resveratrol and its glycosylated derivative as possible complementary treatments for periodontitis and their potential for development as innovative therapeutic strategies. In addition, we present evidence and discuss the mechanisms of action of resveratrol and THSG on periodontitis, focusing on Porphyromonas gingivalis-induced inflammatory responses in human gingival fibroblasts and animal modeling of ligature-induced periodontitis. We also illuminate the signal transduction pathways and the cytokines involved.

Mechanisms of action of nonpeptide hormones on resveratrol-induced antiproliferation of cancer cells.

Nonpeptide hormones, such as thyroid hormone, dihydrotestosterone, and estrogen, have been shown to stimulate cancer proliferation via different mechanisms. Aside from their cytosolic or membrane-bound receptors, there are receptors on integrin αv ß3 for nonpeptide hormones. Interaction between hormones and integrin αv ß3 can induce signal transduction and eventually stimulate cancer cell proliferation. Resveratrol induces inducible COX-2-dependent antiproliferation via integrin αv ß3 . Resveratrol and hormone-induced signals are both transduced by activated extracellular-regulated kinases 1 and 2 (ERK1/2); however, hormones promote cell proliferation, while resveratrol induces antiproliferation in cancer cells. Hormones inhibit resveratrol-stimulated phosphorylation of p53 on Ser15, resveratrol-induced nuclear COX-2 accumulation, and formation of p53-COX-2 nuclear complexes. Subsequently, hormones impair resveratrol-induced COX-2-/p53-dependent gene expression. The inhibitory effects of hormones on resveratrol action can be blocked by different antagonists of specific nonpeptide hormone receptors but not integrin αv ß3 blockers. Results suggest that nonpeptide hormones inhibit resveratrol-induced antiproliferation in cancer cells downstream of the interaction between ligand and receptor and ERK1/2 activation to interfere with nuclear COX-2 accumulation. Thus, the surface receptor sites for resveratrol and nonpeptide hormones are distinct and can induce discrete ERK1/2-dependent downstream antiproliferation biological activities. It also indicates the complex pathways by which antiproliferation is induced by resveratrol in various physiological hormonal environments. .

Leptin OB3 peptide suppresses leptin-induced signaling and progression in ovarian cancer cells.

BACKGROUND: Obesity and its comorbidities constitute a serious health burden worldwide. Leptin plays an important role in diet control; however, it has a stimulatory potential on cancer cell proliferation. The OB3 peptide, a synthetic peptide, was shown to be more active than leptin in regulating metabolism but with no mitogenic effects in cancer cells. METHODS: In this study, we investigated the proliferative effects, gene expressions and signaling pathways modulated by leptin and OB3 in human ovarian cancer cells. In addition, an animal study was performed. RESULTS: Leptin, but not OB3, induced the proliferation of ovarian cancer cells. Interestingly, OB3 blocked the leptin-induced proliferative effect when it was co-applied with leptin. Both leptin and OB3 activated the phosphatidylinositol-3-kinase (PI3K) signal transduction pathway. In addition, leptin stimulated the phosphorylation of signal transducer and activator of transcription-3 (STAT3) Tyr-705 as well as estrogen receptor (ER)α, and the expression of ERα-responsive genes. Interestingly, all leptin-induced signal activation and gene expressions were blocked by the co-incubation with OB3 and the inhibition of extracellular signal-regulated kinase (ERK)1/2. Coincidently, leptin, but not OB3, increased circulating levels of follicle-stimulating hormone (FSH) which is known to play important roles in the initiation and proliferation of ovarian cancer cells. CONCLUSIONS: In summary, our findings suggest that the OB3 peptide may prevent leptin-induced ovarian cancer initiation and progression by disrupting leptin-induced proliferative signals via STAT3 phosphorylation and ERα activation. Therefore, the OB3 peptide is a potential anticancer agent that might be employed to prevent leptin-induced cancers in obese people.

2,3,5,4'-Tetrahydroxystilbene-2-O-ß-glucoside Isolated from Polygoni Multiflori Ameliorates the Development of Periodontitis.

Periodontitis, a chronic infection by periodontopathic bacteria, induces uncontrolled inflammation, which leads to periodontal tissue destruction. 2,3,5,4'-Tetrahydroxystilbene-2-O-beta-glucoside (THSG), a polyphenol extracted from Polygoni Multiflori, reportedly has anti-inflammatory properties. In this study, we investigated the mechanisms of THSG on the Porphyromonas gingivalis-induced inflammatory responses in human gingival fibroblasts and animal modeling of ligature-induced periodontitis. Human gingival fibroblast cells were treated with lipopolysaccharide (LPS) extracted from P. gingivalis in the presence of resveratrol or THSG to analyze the expression of TNF-α, IL-1ß, and IL-6 genes. Increased AMP-activated protein kinase (AMPK) activation and SirT1 expression were induced by THSG. Treatment of THSG decreased the expression of LPS-induced inflammatory cytokines, enhanced AMPK activation, and increased the expression of SirT1. In addition, it suppressed the activation of NF-κB when cells were stimulated with P. gingivalis LPS. The anti-inflammatory effect of THSG and P. Multiflori crude extracts was reproduced in ligature-induced periodontitis animal modeling. In conclusion, THSG inhibited the inflammatory responses of P. gingivalis-stimulated human gingival fibroblasts and ameliorated ligature-induced periodontitis in animal model.

Thyroid Hormone, Cancer, and Apoptosis.

Thyroid hormones play important roles in regulating normal metabolism, development, and growth. They also stimulate cancer cell proliferation. Their metabolic and developmental effects and growth effects in normal tissues are mediated primarily by nuclear hormone receptors. A cell surface receptor for the hormone on integrin [alpha]vß3 is the initiation site for effects on tumor cells. Clinical hypothyroidism may retard cancer growth, and hyperthyroidism was recently linked to the prevalence of certain cancers. Local levels of thyroid hormones are controlled through activation and deactivation of iodothyronine deiodinases in different organs. The relative activities of different deiodinases that exist in tissues or organs also affect the progression and development of specific types of cancers. In this review, the effects of thyroid hormone on signaling pathways in breast, brain, liver, thyroid, and colon cancers are discussed. The importance of nuclear thyroid hormone receptor isoforms and of the hormone receptor on the extracellular domain of integrin [alpha]vß3 as potential cancer risk factors and therapeutic targets are addressed. We analyze the intracellular signaling pathways activated by thyroid hormones in cancer progression in hyperthyroidism or at physiological concentrations in the euthyroid state. Determining how to utilize the deaminated thyroid hormone analog (tetrac), and its nanoparticulate derivative to reduce risks of cancer progression, enhance therapeutic outcomes, and prevent cancer recurrence is also deliberated. © 2016 American Physiological Society. Compr Physiol 6:1221-1237, 2016.

Actions of l-thyroxine and Nano-diamino-tetrac (Nanotetrac) on PD-L1 in cancer cells.

The PD-1 (programmed death-1)/PD-L1 (PD-ligand 1) checkpoint is a critical regulator of activated T cell-cancer cell interactions, defending tumor cells against immune destruction. Nano-diamino-tetrac (NDAT; Nanotetrac) is an anticancer/anti-angiogenic agent targeted to the thyroid hormone-tetrac receptor on the extracellular domain of integrin αvß3. NDAT inhibits the cancer cell PI3-K and MAPK signal transduction pathways that are critical to PD-L1 gene expression. We examined actions in vitro of thyroid hormone (l-thyroxine, T4) and NDAT on PD-L1 mRNA abundance (qPCR) and PD-L1 protein content in human breast cancer (MDA-MB-231) cells and colon carcinoma (HCT116 and HT-29) cells. In MDA-MB-231 cells, a physiological concentration of T4 (10-7M total; 10-10M free hormone) stimulated PD-L1 gene expression by 38% and increased PD-L1 protein by 2.7-fold (p<0.05, all changes). NDAT (10-7M) reduced PD-L1 in T4-exposed cells by 21% (mRNA) and 39% (protein) (p<0.05, all changes). In HCT116 cells, T4 enhanced PD-L1 gene expression by 17% and protein content by 24% (p<0.05). NDAT reduced basal PD-L1 mRNA by 35% and protein by 31% and in T4-treated cells lowered mRNA by 33% and protein by 66%. In HT-29 cells, T4 increased PD-L1 mRNA by 62% and protein by 27%. NDAT lowered basal and T4-stimulated responses in PD-L1 mRNA and protein by 35-40% (p<0.05). Activation of ERK1/2 was involved in T4-induced PD-L1 accumulation. We propose that, by a nongenomic mechanism, endogenous T4 may clinically support activity of the defensive PD-1/PD-L1 checkpoint in tumor cells. NDAT non-immunologically suppresses basal and T4-induced PD-L1 gene expression and protein accumulation in cancer cells.

Novel leptin OB3 peptide-induced signaling and progression in thyroid cancers: Comparison with leptin.

Obesity results in increased secretion of cytokines from adipose tissue and is a risk factor for various cancers. Leptin is largely produced by adipose tissue and cancer cells. It induces cell proliferation and may serve to induce various cancers. OB3-leptin peptide (OB3) is a new class of functional leptin peptide. However, its mitogenic effect has not been determined. In the present study, because of a close link between leptin and the hypothalamic-pituitary-thyroid axis, OB3 was compared with leptin in different thyroid cancer cells for gene expression, proliferation and invasion. Neither agent stimulated cell proliferation. Leptin stimulated cell invasion, but reduced adhesion in anaplastic thyroid cancer cells. Activated ERK1/2 and STAT3 contributed to leptin-induced invasion. In contrast, OB3 did not affect expression of genes involved in proliferation and invasion. In vivo studies in the mouse showed that leptin, but not OB3, significantly increased circulating levels of thyrotropin (TSH), a growth factor for thyroid cancer. In summary, OB3 is a derivative of leptin that importantly lacks the mitogenic effects of leptin on thyroid cancer cells.

Corrigendum: "Cancer Cell Gene Expression Modulated from Plasma Membrane Integrin αvß3 by Thyroid Hormone and Nanoparticulate Tetrac".

[This corrects the article on p. 240 in vol. 5, PMID: 25628605.].