Guofang Chen

Metformin Inhibits Growth of Thyroid Carcinoma Cells, Suppresses Self-Renewal of Derived Cancer Stem Cells, and Potentiates the Effect of Chemotherapeutic Agents

CONTEXT Hyperinsulinemia and insulin resistance are the major reasons for a higher prevalence of several cancer entities in type 2 diabetes mellitus and obesity. Metformin exerts a growth-inhibitory effect by reducing hyperinsulinemia and by a direct cellular action. OBJECTIVE We investigated the effect of metformin on growth of differentiated human thyroid cells, anaplastic thyroid carcinoma cells, a doxorubicin-resistant thyroid carcinoma cell line, and thyroid cancer stem cells. DESIGN The antimitogenic effect of metformin was studied in thyroid cells derived from goiters and in thyroid carcinoma cell lines by analysis of cell growth, cell cycle progression, and apoptosis. Furthermore, the influence of pretreatment with insulin or with chemotherapeutic agents on metformin-induced growth inhibition was investigated in thyroid carcinoma cells, in a doxorubicin-resistant thyroid carcinoma cell line, and in derived carcinoma stem cells. RESULTS Metformin showed an antimitogenic effect by inhibition of cell cycle progression and induction of apoptosis. In addition, metformin antagonized the growth-stimulatory effect of insulin, inhibited clonal cell growth, reduced thyroid cancer sphere formation, and potentiated the antimitogenic effect of chemotherapeutic agents such as doxorubicin and cisplatin on undifferentiated thyroid carcinoma cells. Remarkably, the antiproliferative effect of metformin was even found in a doxorubicin-resistant thyroid carcinoma cell line. The growth-inhibitory effect of metformin was, however, not restricted to differentiated thyroid cells and undifferentiated thyroid carcinoma cells but was also demonstrated in thyroid carcinoma cancer stem cells. CONCLUSIONS Metformin markedly diminished growth stimulation by insulin and showed an additive antimitogenic effect to chemotherapeutics agents. Therefore, our results suggest this drug as adjuvant treatment for thyroid cancer in type 2 diabetic patients.

Selenium Supplementation for Autoimmune Thyroiditis: A Systematic Review and Meta-Analysis

Many studies have reported that selenium (Se) has a close relationship with autoimmune thyroiditis (AIT). The therapeutic effect of Se supplementation in AIT treatment remains unclear. The objective of the present study was to determine the efficacy of Se supplementation for the treatment of AIT. A structured literature search was undertaken to identify all randomized controlled trials conducted in patients with AIT receiving Se supplementation or placebo. Nine studies enrolling a total of 787 patients were included. The results showed that Se supplementation with duration 6 months significantly dropped the TPOAb titers but did not decrease the TgAb titers. Patients assigned to Se supplementation for 12-month duration showed significantly lower TPOAb titers and TgAb titers. Patients after Se supplementation had a higher chance to improve the mood or well-being compared with controls. Se supplementation is associated with a significant decrease in TPOAb titers at 6 and 12 months; meanwhile, the TgAb titers can be dropped at 12 months. After Se supplementation treatment, patients had a higher chance to improve the mood without significant adverse events.

Oestrogen action on thyroid progenitor cells: relevant for the pathogenesis of thyroid nodules?

Benign and malignant thyroid nodules are more prevalent in females than in males. Experimental data suggest that the proliferative effect of oestrogen rather than polymorphisms is responsible for this gender difference. This study analysed whether both differentiated thyroid cells and thyroid stem and progenitor cells are targets of oestrogen action. In thyroid stem/progenitor cells derived from nodular goitres, the ability of 17β-oestradiol (E₂) to induce the formation of thyrospheres and the expression of oestrogen receptors (ERs) and the effect of E₂ on the growth and expression of markers of stem cells and thyroid differentiation (TSH receptor, thyroperoxidase, thyroglobulin and sodium iodide symporter (NIS)) were analysed. E₂ induced thyrosphere formation, albeit to a lower extent than other growth factors. Thyroid stem and progenitor cells expressed ERα (ESR1) and ERβ (ESR2) with eight times higher expression levels of ERα mRNA compared with the differentiated thyrocytes. E₂ was a potent stimulator of the growth of thyroid stem/progenitor cells. In contrast, TSH-induced differentiation of progenitor cells, in particular, the expression of NIS, was significantly inhibited by E₂. In conclusion, oestrogen stimulated the growth and simultaneously inhibited the differentiation of thyroid nodule-derived stem/progenitor cells. From these data and based on the concept of cellular heterogeneity, we hypothesize a supportive role of oestrogen in the propagation of thyroid stem/progenitor cells leading to the selection of a progeny of growth-prone cells with a decreased differentiation. These cells may be the origin of hypofunctioning or non-functioning thyroid nodules in females.

Synergistic anti-proliferative effect of metformin and sorafenib on growth of anaplastic thyroid cancer cells and their stem cells

Sorafenib, a multikinase inhibitor has recently been approved for the treatment of radio-iodine refractory thyroid carcinoma. However, toxic side effects may lead to dose reduction. In the present study, we analyzed whether a combined therapy with metformin may allow a dose reduction of sorafenib without loss of effectiveness at the same time. In HTh74 anaplastic thyroid carcinoma (ATC) cells and its derived doxorubicin-resistant HTh74Rdox cell line, the growth inhibitory effect of sorafenib with or without metformin was investigated. Furthermore, an analysis of cell cycle arrest in response to sorafenib was performed and the ability of a combined treatment to induce apoptosis was analyzed. In addition, the effects on clonal growth and formation of stem cell-derived spheres were assayed. The influence of sorafenib and metformin on MAP kinase pathway was investigated by analysis of ERK phosphorylation. Sorafenib and metformin synergistically inhibited growth of the two thyroid cancer cell lines, with a more pronounced effect on the doxorubicin-resistant HTh74Rdox cell line. The two drugs also synergistically decreased sphere formation, which suggested a specific effect on thyroid cancer stem cells. The addition of metformin enabled a 25% dose reduction of sorafenib without loss of its growth inhibitory efficacy. Sorafenib and metformin synergistically decreased the proliferation of ATC cell lines and the outgrowth of their derived cancer stem cells. A combined treatment enabled a significant dose reduction of sorafenib. In respect to frequent toxic side effects, clinical studies in future should demonstrate whether the addition of metformin may be an advantage in the chemotherapy of patients with radio-iodine‑resistant thyroid cancer.

Association between ADIPOQ +45T>G Polymorphism and Type 2 Diabetes: A Systematic Review and Meta-Analysis

Recently, a number of studies have reported the association between the single nucleotide polymorphisms (SNPs) +45T>G polymorphism in the adiponectin (ADIPOQ) gene and type 2 diabetes mellitus (T2DM) risk, though the results are inconsistent. In order to obtain a more precise estimation of the relationship, a meta-analysis was performed. In this current study, the Medline, Embase, Pubmed, ISI Web of Knowledge, Ovid, Science Citation Index Expanded Database, Wanfang Database, and China National Knowledge Infrastructure were searched for eligible studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of association. Forty-five publications were included in the final meta-analysis with 9986 T2DM patients and 16,222 controls for ADIPOQ +45T>G polymorphism according to our inclusion and exclusion criteria. The +45T>G polymorphism was associated with an overall significantly increased risk of T2DM (G vs. T: OR = 1.18, 95% CI = 1.06–1.32; The dominant model: OR = 1.18, 95% CI = 1.03–1.33; The recessive model: OR = 1.47, 95% CI = 1.20–1.78; The homozygous model: OR = 1.62, 95% CI = 1.25–2.09; Except the heterozygous model: OR = 1.11, 95% CI = 0.98–1.24). Subgroup analysis revealed a significant association between the +45T>G polymorphism and T2D in an Asian population. Thus, this meta-analysis indicates that the G allele of the ADIPOQ +45T>G polymorphisms associated with a significantly increased risk of T2DM in the Asian population.

Metformin and thyroid disease

An intriguing area of research in thyroidology is the recently discovered association of insulin resistance with thyroid functional and morphological abnormalities. Individuals with hyperinsulinemia have larger thyroid gland and a higher prevalence of thyroid nodules and cancer. Accordingly, patients treated with metformin have a smaller thyroid volume and a lower risk of incident goiter, thyroid nodule and cancer. Multiple studies in vitro and in vivo have demonstrated that metformin can inhibit the growth of thyroid cells and different types of thyroid cancer cells by affecting the insulin/IGF1 and mTOR pathways. Besides, metformin treatment was associated with a decrease in the levels of serum thyroid-stimulating hormone (TSH) in diabetic patients possibly by enhancing the effects of thyroid hormones in the pituitary and activating the adenosine monophosphate-activated protein kinase (AMPK). Based on this evidence, metformin appears to be a promising therapeutic tool in patients with thyroid disease. More clinical studies are necessary to evaluate the clinical significance of metformin for the treatment of thyroid diseases.

Neutral ceramidase activity inhibition is involved in palmitate-induced apoptosis in INS-1 cells

Neutral ceramidase (NCDase) is a class of ceramidases, a key enzyme in ceramide degradation. Recently, it was observed that NCDase activity was suppressed by saturated fatty acids to increase ceramide content in rat muscle. However, little is known about its changes in activity and roles in palmitate (Palm)-induced lipotoxicity in pancreatic β cells. Here, we demonstrated that Palm treatment significantly down-regulated NCDase activity, mRNA and protein levels in rat INS-1 cells. In addition, Palm caused a significant accumulation of ceramide, while SPH level remained unchanged, suggesting that inhibition of NCDase activity led to no change of SPH level after treatment with Palm for 24 h. Furthermore, NCDase overexpression significantly reduced Palm-induced apoptosis in INS-1 cells. Conversely, NCDase siRNA knockdown markedly exacerbated Palm-induced apoptosis. In conclusion, Palm treatment suppressed the activity of NCDase and down-regulated its mRNA and protein expression. Furthermore, NCDase inhibition was involved in Palm-induced apoptosis by blocking ceramide degradation in INS-1 cells.

Elephantiasis in a Patient with EMO Syndrome

Exophthalmos, myxedema and osteoarthropathy (EMO) comprise the triad known as EMO syndrome. Thyroid dysfunction followed by Graves’ ophthalmopathy (GO) commonly was its classic manifestation. The elephantiasic variant was rarely seen. Herein, we reported an unusual case of EMO syndrome associated with severe elephantiasic subtype of pretibial myxedema.

Graves’ disease coexisting with resistance to thyroid hormone: a rare case

A rare case of resistance to thyroid hormone (RTH) complicated with Graves’ hyperthyroidism was reported. The management of this disease is similar to that of Graves’ disease. Antithyroid drug therapy is the first choice, and iodine therapy and surgery are not recommended due to the possibility of severe hypothyroidism and enlargement of the pituitary gland.