Regulation of leptin receptor expression in human papillary thyroid cancer cells

Understanding the effect of obesity on papillary thyroid cancer: is there a need for tailored diagnostic and therapeutic management?

INTRODUCTION

Several studies have focused on the relationship between obesity and differentiated thyroid carcinoma (DTC), particularly papillary histotype (PTC). However, the association of obesity with both incidence and aggressiveness of PTC is still incompletely understood.

AREAS COVERED

We reviewed the mechanisms underlying the cross talk between obesity and thyroid carcinomas and described the most recent evidence evaluating the effect of obesity on the development of PTC, as well as the impact of excessive body weight on the clinicopathologic features and outcome of this type of cancer.

EXPERT OPINION

Available evidence suggests that excessive body weight is linked with a higher risk of getting PTC, while its impact on the aggressiveness of the disease, if present, is still not clear. Therefore, while attention should be paid to discover thyroid cancer in patients with obesity earlier, once diagnosed it should be managed following a conventional workup as in normal weight patients, based on the clinical presentation of the disease and including active surveillance if appropriate, as recommended by referral guidelines.

Critical clinical gaps in cancer precision nanomedicine development

Active targeting strategy is adopted in nanomedicine for cancer treatment. Personalizing the nanomedicine in accordance with patients' omics, under the precision medicine platform, is met with challenges in targeting ligand and matrix material selection at nanoformulation stage. The past 5-year literatures show that the nanoparticulate targeting ligand and matrix material are not selected based upon the cancer omics profiles of patients. The expression of cancer cellular target receptors and metabolizing enzymes is primarily influenced by age, gender, race/ethnic group and geographical origin of patients. The personalized perspective of a nanomedicine cannot be realised with premature digestion of matrix and targeting ligand by specific metabolizing enzymes that are overexpressed by the patients, and unmatched targeting ligand to the majority of cell surface receptors overexpressed in cancer. Omics analysis of individual metabolizing enzyme and cancer cell surface receptor expressed in cancer facilitates targeting ligand and matrix material selection in nanomedicine development.

Renal Cell Cancer and Obesity

Cancers are a frequent cause of morbidity and mortality. There are many risk factors for tumours, including advanced age, personal or family history of cancer, some types of viral infections, exposure to radiation and some chemicals, smoking and alcohol consumption, as well as obesity. Increasing evidence suggest the role of obesity in the initiation and progression of various cancers, including renal cell carcinoma. Since tumours require energy for their uncontrollable growth, it appears plausible that their initiation and development is associated with the dysregulation of cells metabolism. Thus, any state characterised by an intake of excessive energy and nutrients may favour the development of various cancers. There are many factors that promote the development of renal cell carcinoma, including hypoxia, inflammation, insulin resistance, excessive adipose tissue and adipokines and others. There are also many obesity-related alterations in genes expression, including DNA methylation, single nucleotide polymorphisms, histone modification and miRNAs that can promote renal carcinogenesis. This review focuses on the impact of obesity on the risk of renal cancers development, their aggressiveness and patients’ survival.

Histone Deacetylase Inhibitors and Papillary Thyroid Cancer

BACKGROUND/AIM

Papillary Thyroid Cancer (PTC) is the most common type of endocrine malignancy. Although PTC has an excellent prognosis, the recurrent or metastatic disease could affect patients' survival. Recent studies show that Histone Deacetylase Inhibitors (HDACIs) might be promising anticancer agents against PTC. The aim of this review is to evaluate the role of HDACIs as an additional modality in PTC treatment and to depict the latest trends of current research on this field.

MATERIALS AND METHODS

This literature review was performed using the MEDLINE database. The search strategy included terms: "thyroid cancer", "papillary", "HDAC", "histone", and "deacetylase".

RESULTS

Agents, such as Suberoyl Anilide Hydroxamic Acid, Trichostatin A, Valproic Acid, Sodium butyrate, Panobinostat, Belinostat, Romidepsin, CUDC907 and N-Hydroxy-7-(2-naphthylthio)-Hepanomide have shown promising anti-cancer effects on PTC cell lines but fail to trigger a major response in clinical trials.

CONCLUSION

HDACIs have no significant effect as monotherapy against PTC, but further research needs to be conducted in order to investigate their potential effect when used as an additional modality.

Association between adipokines and thyroid carcinoma: a meta-analysis of case-control studies

Background

The incidence of thyroid carcinoma is increasing all over the world. Some studies have suggested that the change of adipokines expression can induce thyroid carcinoma. However, other studies have come to the opposite conclusion. Therefore, we studied the relationship between adipokines and thyroid carcinoma.

Methods

Databases—PubMed, Cochrane Library, SinoMed, CNKI, Wanfang, and clinical trial registries were searched. A meta-analysis was then performed through a fixed or random-effects model to calculate I values for heterogeneity analysis.

Results

Twenty-nine articles were finally included for analysis. The level of serum tumor necrosis factor-alpha (TNF-α) [standardized mean difference (SMD) =1.31, 95% confidence interval (95% CI): 0.35 to 2.28, I² = 98%, P = 0.008] and the ratio of TNF-α immunoreactivity in tissues [odds ratios (OR) =6.36, 95% CI: 1.92 to 21.05, I² = 66%, P = 0.002] in thyroid carcinoma are significantly higher than those in control. The serum interleukin-6 (IL-6) in patients with thyroid carcinoma is higher than that in control (SMD = 1.04, 95% CI: 0.40 to 1.67, I² = 96%, P = 0.001). There is no significant difference of the ratio of IL-6 immunoreactivity in tissues between carcinoma and control (OR = 1.23, 95% CI: 0.62 to 2.43, I² = 86%, P = 0.55). The ratio of leptin immunoreactivity in tissues is significantly associated with the risk of thyroid carcinoma (OR = 12.21, 95% CI: 3.36 to 44.40, I² = 85%, P < 0.00001). However, after analyzing the expression level of serum adiponectin in three studies, no significant difference is found between thyroid carcinoma and the control (P = 0.81).

Conclusions

Adipokines (TNF-α, IL-6 and leptin) show a strong relationship between elevated concentrations (in serum and/or tissue) and thyroid carcinoma. However, the association between adiponectin and thyroid carcinoma needs further research.

Circulating adipokines and metabolic setting in differentiated thyroid cancer

The associative link relating insulin resistance (IR) and adipokines to the occurrence and phenotype of differentiated thyroid cancer (DTC) is unknown. The aim of this study was to evaluate the relationship between IR and adipokines in DTC patients, as compared with carriers of benign thyroid diseases (BTD) and healthy controls. This observational study enrolled 77 subjects phenotyped as DTC (N = 30), BTD (N = 27) and healthy subjects (N = 20). Each subject underwent preoperative analysis of anthropometric parameters, thyroid function and autoimmunity, insulin resistance (HOMA-IR) and levels of unacylated (UAG) and acylated ghrelin (AG), obestatin, leptin and adiponectin. Multivariate regression models were used to test the predictive role of metabolic correlates on thyroid phenotypes and DTC extension. The three groups showed similar age, gender distribution, smoking habit, BMI and thyroid parameters. Obestatin was significantly higher in DTC group compared to BTD (P < 0.05) and control subjects (P < 0.0001). DTC and BTD groups showed higher levels of UAG (P < 0.01) and AG (P < 0.05). Leptin levels were comparable between groups, whereas adiponectin levels were lower in DTC compared to BTD group (P < 0.0001) and controls (P < 0.01). In parallel, HOMA-IR was higher in DTC than BTD (P < 0.05) and control group (P < 0.01). Stepwise multivariable regression analysis showed that obestatin and UAG were independent predictors of DTC (P = 0.01 for both). In an analysis restricted to the DTC group, obestatin levels were associated with the absence of lymph node metastases (P < 0.05). Our results highlight a potential association between metabolic setting, circulating adipokines and thyroid cancer phenotype.

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.

Prognostic significance of promoter CpG island methylation of obesity-related genes in patients with nonmetastatic renal cell carcinoma

BACKGROUND

Greater than 40% of renal cell carcinoma (RCC) cases in the United States are attributed to excessive body weight. Moreover, obesity also may be linked to RCC prognosis. However, the molecular mechanisms underlying these associations are unclear. In the current study, the authors evaluated the role of promoter methylation in obesity-related genes in RCC tumorigenesis and disease recurrence.

METHODS

Paired tumors (TU) and normal adjacent (N-Adj) tissues from 240 newly diagnosed and previously untreated white patients with RCC were examined. For the discovery phase, 63 RCC pairs were analyzed. An additional 177 RCC pairs were evaluated for validation. Pyrosequencing was used to determine CpG methylation in 20 candidate obesity-related genes. An independent data set from The Cancer Genome Atlas also was analyzed for functional validation. The association between methylation and disease recurrence was analyzed using multivariate Cox proportional hazards models and Kaplan-Meier survival analysis.

RESULTS

Methylation in neuropeptide Y (NPY), leptin (LEP), and leptin receptor (LEPR) was significantly higher in TU compared with N-Adj tissues (P<.0001) in both the discovery and validation groups. High methylation in LEPR was associated with an increased risk of disease recurrence (hazard ratio, 3.15; 95% confidence interval, 1.23-8.07 [P = .02]). Patients with high methylation in LEPR had a shorter recurrence-free survival compared with patients in the low-methylation group (log-rank P = 2.25 × 10^-3 ). In addition, high LEPR methylation in TU was associated with more advanced features (P≤.05). Consistent with the findings of the current study, lower LEPR expression in TU compared with N-Adj tissues (P = 1.00 × 10^-3 ) was found in data from The Cancer Genome Atlas.

CONCLUSIONS

Somatic alterations of promoter methylation in the NPY, LEP, and LEPR genes are involved in RCC tumorigenesis. Furthermore, LEPR methylation appears to be associated with RCC recurrence. Future research to elucidate the biology underlying this association is warranted. Cancer 2017;123:3617-27. © 2017 American Cancer Society.

CD74 expression and its therapeutic potential in thyroid carcinoma

CD74, the invariant chain of major histocompatibility complex class II, is also a receptor for macrophage migration inhibitory factor (MIF). CD74 and MIF have been associated with tumor progression and metastasis in hematologic and solid tumors. In this study, we found that 60 and 65% of papillary thyroid cancers were positive for CD74 and MIF immunohistochemical staining respectively. Anaplastic thyroid cancer was negative for MIF, but mostly positive for CD74 expression. Normal thyroid tissue and follicular adenomas were negative for CD74 expression. CD74 expression in papillary thyroid cancer was associated with larger tumor size (P=0.043), extrathyroidal invasion (P=0.021), advanced TNM stage (P=0.006), and higher MACIS score (P=0.026). No clinicopathological parameter was associated with MIF expression. Treatment with anti-CD74 antibody in thyroid cancer cells inhibited cell growth, colony formation, cell migration and invasion, and vascular endothelial growth factor secretion. In contrast, treatment with recombinant MIF induced an increase in cell invasion. Anti-CD74 treatment reduced AKT phosphorylation and stimulated AMPK activation. Our findings suggest that CD74 overexpression in thyroid cancer is associated with advanced tumor stage and may serve as a therapeutic target.

Insights into genetic and epigenetic determinants with impact on vitamin d signaling and cancer association studies: the case of thyroid cancer

Vitamin D is a key regulator of calcium metabolism and has been implicated as a cancer preventive agent. However, clinical studies have revealed conflicting results on its cancer preventive properties, attributed in part to multiple metabolic and regulatory factors susceptible to affect individual responses to exogenous vitamin D. Vitamin D is obtained from dietary sources and sun exposure, which depends on numerous parameters such as skin type, latitude, and lifestyle factors. Focusing on thyroid cancer (TC), we document that genetic and epigenetic determinants can greatly impact individual response to vitamin D and may outweigh the classical clinical correlative studies that focus on sun exposure/dietary intake factors. In particular, genetic determinants innate to host intrinsic metabolic pathways such as highly polymorphic cytochromes P450s responsible for the metabolic activation of vitamin D are expressed in many organs, including the thyroid gland and can impact vitamin D interaction with its nuclear receptor (VDR) in thyroid tissue. Moreover, downstream regulatory pathways in vitamin D signaling as well as VDR are also subject to wide genetic variability among human populations as shown by genome-wide studies. These genetic variations in multiple components of vitamin D pathways are critical determinants for the revaluation of the potential preventive and anticancer properties of vitamin D in TC.

Obesity and thyroid cancer

Many studies have provided observational data on the association of obesity and thyroid cancers, but only few of them propose mechanisms that would permit a better understanding of the causal molecular mechanisms of this association. Considering that there is an increasing incidence of both obesity and thyroid cancers, we need to summarize and link recent studies in order to characterize and understand the contribution of obesity-related factors that might affect thyroid cancer development and progression. Adipose tissue is involved in many vital processes, including insulin sensitivity, angiogenesis, regulation of energy balance, activation of the complement system, and responses such as inflammation. Although these processes have their own molecular pathways, they involve the same molecules through which obesity and adipose tissue might exert their roles in carcinogenesis, not only affecting MAPK and PI3K or even insulin pathways, but also recruiting local inflammatory responses that could result in disease formation and progression. This review describes five important issues that might explain the link between excessive weight and thyroid cancer: thyroid hormones, insulin resistance, adipokines, inflammation, and sexual hormones.

Obesity and thyroid cancer: a clinical update

BACKGROUND

In the last decade, significant contributions have been made to our knowledge on the connection between the thyroid and adipose tissue. Modern society is faced with climbing rates of obesity and metabolic syndrome, and there is accumulating evidence of an association between obesity and increased cancer risk. The aim of this review is to summarize clinical data on the association between thyroid cancer (TC) and obesity and briefly to present plausible hypotheses explaining this interplay.

SUMMARY

We performed a search on the PubMed database for studies published in English from 1980 to March 2013 using the terms "thyroid cancer," "obesity," and "body mass index." Although there is inconsistency among the clinical studies, it seems that overweight and obesity are related to a modestly increased TC risk. Various factors, such as sex, ethnicity, and body changes during certain life periods, for example adolescence, may influence the association between obesity and TC risk. There are preliminary data linking obesity with a less favorable clinicopathologic profile of TC. However, validation with larger multicenter studies is needed. The precise underlying mechanisms have not yet been elucidated, but the insulin-IGF axis and adipokines, such as leptin and adiponectin, might be implicated in the link between excess weight and TC.

CONCLUSIONS

Given the rising prevalence of TC and the development of obesity as an epidemic, it is important to clarify its connection with TC as well as the mediating pathways. However, unless this association is confirmed and causation proven, screening for TC in overweight and obese subjects-a rapidly increasing body of the general population-does not seem justified.

Obesity and thyroid cancer: epidemiologic associations and underlying mechanisms

The incidence of thyroid cancer has been rising over the past few decades along with a parallel increase in obesity. Observational studies have provided evidence for a potential association between the two. By contrast, clinical data for a link between type 2 diabetes mellitus, a condition strongly associated with obesity, and thyroid cancer are limited and largely not supportive of such an association. Obesity leads to hypoadiponectinemia, a pro-inflammatory state, and insulin resistance, which, in turn, leads to high circulating insulin and insulin-like growth factor-1 levels, thereby possibly increasing the risk for thyroid cancer. Thus, insulin resistance possibly plays a pivotal role in underlying the observed association between obesity and thyroid cancer, potentially leading to the development and/or progression of thyroid cancer, through its interconnections with other factors including insulin-like growth factor-1, adipocytokines/cytokines and thyroid-stimulating hormone. In this review, epidemiological and clinical evidence and potential mechanisms underlying the proposed association between obesity and thyroid cancer risk are reviewed. If the association between obesity and thyroid cancer demonstrated in observational studies proves to be causal, targeting obesity (and/or downstream mediators of risk) could be of importance in the prevention and management of thyroid cancer.

Importance of epigenetic changes in cancer etiology, pathogenesis, clinical profiling, and treatment: what can be learned from hematologic malignancies?

Epigenetic alterations represent a key cancer hallmark, even in hematologic malignancies (HMs) or blood cancers, whose clinical features display a high inter-individual variability. Evidence accumulated in recent years indicates that inactivating DNA hypermethylation preferentially targets the subset of polycomb group (PcG) genes that are regulators of developmental processes. Conversely, activating DNA hypomethylation targets oncogenic signaling pathway genes, but outcomes of both events lead in the overexpression of oncogenic signaling pathways that contribute to the stem-like state of cancer cells. On the basis of recent evidence from population-based, clinical and experimental studies, we hypothesize that factors associated with risk for developing a HM, such as metabolic syndrome and chronic inflammation, trigger epigenetic mechanisms to increase the transcriptional expression of oncogenes and activate oncogenic signaling pathways. Among others, signaling pathways associated with such risk factors include pro-inflammatory nuclear factor κB (NF-κB), and mitogenic, growth, and survival Janus kinase (JAK) intracellular non-receptor tyrosine kinase-triggered pathways, which include signaling pathways such as transducer and activator of transcription (STAT), Ras GTPases/mitogen-activated protein kinases (MAPKs)/extracellular signal-related kinases (ERKs), phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR), and β-catenin pathways. Recent findings on epigenetic mechanisms at work in HMs and their importance in the etiology and pathogenesis of these diseases are herein summarized and discussed. Furthermore, the role of epigenetic processes in the determination of biological identity, the consequences for interindividual variability in disease clinical profile, and the potential of epigenetic drugs in HMs are also considered.

Clinicopathological implications of leptin and leptin receptor expression in papillary thyroid cancer

The role of leptin and its receptors (OBRs) in the pathogenesis of various primary human malignancies has been demonstrated. However, their expression and clinicopathological significance in papillary thyroid cancer (PTC) is not fully understood. In this study, we examined the expression of leptin and OBRs in 76 PTC samples using immunohistochemistry, and their associations with clinicopathological parameters were evaluated. The expression of OBRs was observed in the tumor cell membrane and/or cytoplasm, with a positive rate of 73.7% (56/76), while leptin was expressed in the tumor cell cytoplasm in 55 of 76 cases (72.4%). The expression of either protein was associated with greater tumor size (P=0.016 for leptin and P=0.002 for OBRs). In addition, the expression levels of leptin and OBRs were associated with each other. Neither leptin nor OBR expression levels were associated with other parameters, including age, body weight, postmenopausal state, multifocality and lymph node metastasis. These data suggest that the expression of leptin and/or OBRs in PTC is associated with tumor size and may be a potential target in PTC.