RAP1GAP Functions as a Tumor Suppressor Gene and Is Regulated by DNA Methylation in Differentiated Thyroid Cancer.

Inactivation of tumor suppressor genes, such as RAP1GAP, by hypermethylation of their regulatory region can give rise to thyroid tumors. The aim of this study was to investigate the expression of the RAP1GAP gene and the DNA methylation patterns of its CpG74a, CpG74b, and CpG24 in an Iranian population with differentiated thyroid cancer (DTC). In this study, 160 individuals who underwent thyroidectomy in the Tehran Erfan Hospital between 2018 and 2020 were selected. DNA methylation patterns of selected CpG islands (CpG74a, CpG74b, and CpG24) were determined using methylation-specific PCR. The mRNA expression and protein level of -RAP1GAP were also evaluated. SW1736 and B-CPAP cells were treated with 5-aza-2'-deoxycytidine (5-Aza) to demethylate these regions. The hypermethylation rates of CpG74a and CpG24 in DTC samples were significantly higher than in the control. The mRNA expression and protein level of -RAP1GAP were significantly decreased in the DTC group. In the DTC group, hypermethylation in CpG74a was correlated with decreasing RAP1GAP expression (R2: 0.34; p = 0.043). CpG74a with a specificity of 86.4% has significant prediction power to distinguish between DTC and normal thyroid tissues. Additionally, hypermethylation of CpG74a was significantly associated with higher tumor stages (stage III-IV: 77%; stage I-II: 23%; p = 0.012). Increasing expression of RAP1GAP after demethylation with 15 µM of 5-Aza was observed in both cell lines. These results indicate that DNA hypermethylation in CpG74a can be considered as an epigenetic biomarker in DTC.

Determination of age and sex specific TSH and FT4 reference limits in overweight and obese individuals in an iodine-replete region: Tehran Thyroid Study (TTS).

Introduction: To determine age and sex-specific thyrotropin (TSH) and free thyroxine (FT4) reference ranges according to body mass index (BMI) categories. Methods: With regards to the National Academy of Clinical Biochemistry (NACB) criteria, a total of 2818 individuals from the Tehran Thyroid Study population was selected and categorized in three BMI groups. Results: TSH levels did not differ significantly between BMI groups (p = .054). Females had statistically higher TSH levels than males in all BMI categories (p < .001). According to age-specific analyses, the youngest category (20-29 years) had the highest median values of serum TSH in all BMI groups. With increasing BMI, the 2.5th percentile of TSH remained approximately unchanged and the 97.5th percentile showed an increasing pattern. FT4 level was significantly higher in the normal weight group compared to obese individuals (p < .001); females had significantly lower FT4 levels than males in normal weight and obese groups (p < .001). According to age categories, the youngest group (20-29 years) had higher levels of FT4 than the elderly group in all BMI categories. A decreasing pattern in both 2.5th and 97.5th percentiles of FT4 was observed along with increasing BMI. Conclusions: Compared to the normal weight population, obese individuals have slightly lower FT4 concentrations accompanied by similar TSH levels. With increasing BMI, upper limits of TSH and FT4 show increasing and decreasing patterns, respectively.

The age effect on the association between the scavenger receptor class B type I (SR-BI) polymorphism and HDL-C level: Tehran Lipid and Glucose Study.

INTRODUCTION: The scavenger receptor class B type I (SR-BI) is a key component in the reverse cholesterol transportation. The aim of this study was to assess the association between exon1 (G → A) polymorphism of SR-BI gene and lipid profiles among the Tehran Lipid and Glucose Study (TLGS) population. MATERIALS AND METHODS: This cross-sectional study included 774 adults (322 males and 452 females) aged 20-70 years who were randomly selected from among TLGS population. Anthropometrical and biochemical variables for participants were measured. Selected SR-BI gene polymorphism was determined with restriction fragment length polymorphism, via Alu restriction enzyme. RESULTS: Minor allele frequency for SR-BI polymorphism in the selected population was 0.159. Allele frequencies were in conformity with Hardy-Weinberg equilibrium. Association between (G → A) SR-BI polymorphism and high density lipoprotein cholesterol (HDL-C) and HDL3 was significant only after adjustment for age as a potential covariate (p = 0.046, 0.041, respectively); however, the results did not improve after adjustment for sex. DISCUSSION: The result of this study confirms the role of age as a potential confounder which could modify the association between the SR-BI single nucleotide polymorphism and HDL-C level.

A systematic review of dysregulated microRNAs in Hashimoto's thyroiditis.

BACKGROUND: Plenty of evidence suggests that dysregulated microRNAs are linked to developing autoimmune thyroid diseases. In this study, we aimed to identify commonly linked dysregulated microRNAs in Hashimoto's thyroiditis(HT) and explore microRNA-targeted genes and the involved pathways. METHODS: Embase, PubMed, Web of Science, and Scopus databases were searched using the MeSH terms and free text terms, which yielded 11879 articles published up to July 2023. Two-step screening(first for titles and second for abstracts) was completed according to inclusion and exclusion criteria. The search strategy was formulated using the PEO format(Population, Exposure, and Outcome) for observational studies. The corresponding target genes and relevant signaling pathways were also identified using web servers of Diana Tools/its mirPath v.3 software, miRNA Enrichment Analysis, Mirpath DB2, miRPathDB 2.0, and miRmap. RESULTS: Review inclusion criteria were met by 16 studies. Thirty-three microRNAs were identified as differentially expressed in HT patients compared to a healthy control after qRT-PCR or RNA sequencing confirmation. Only three miR-146a, miR-142, and miR-301 showed significant results in more than two studies comparing HT cases with healthy controls. CONCLUSION: Three key microRNAs in HT were identified by systematic review; the corresponding target genes and signaling pathways involved in the target genes were also identified. These microRNAs regulate the immune response and inflammation and may favor the development and progression of HT. These data may be beneficial to make a step forward to understand the exact etiology of HT and use of these MicroRNAs as possible diagnostic and prognostic biomarkers and as target therapy.

Leisure-time physical activity and its association with metabolic risk factors in Iranian adults: Tehran Lipid and Glucose Study, 2005-2008.

We examined the association between leisure-time physical activity (LTPA) and metabolic syndrome (MetS) among 4,665 randomly selected adults who participated in the Tehran Lipid and Glucose Study, 2005-2008. Normal-weight participants with light LTPA had higher risk of low high-density lipoprotein cholesterol and elevated levels of triglycerides than those with vigorous LTPA. Overweight adults with moderate LTPA had higher risk of having elevated levels of fasting blood glucose than adults with vigorous LTPA and, in the same group, we found an inverse association between light LTPA and MetS after adjustment for sex, age, education levels, smoking, and calorie intake. Although participants in the normal-weight and obese groups with vigorous LTPA had higher risk of high systolic blood pressure than participants with moderate LTPA, this finding had no clinical significance. Increased LTPA is associated with decreased risk of any damaging changes in the markers of MetS.

Heritability of the metabolic syndrome and its components in the Tehran Lipid and Glucose Study (TLGS).

Growing evidence suggests that metabolic syndrome (MetS) has both genetic and environmental bases. We estimated the heritability of the MetS and its components in the families from the Tehran Lipid and Glucose Study (TLGS). We investigated 904 nuclear families in TLGS with two biological parents and at least one offspring (1565 parents and 2448 children), aged 3-90 years, for whom MetS information was available and had at least two members of family with MetS. Variance component methods were used to estimate age and sex adjusted heritability of metabolic syndrome score (MSS) and MetS components using SOLAR software. The heritability of waist circumference (WC), HDL-cholesterol (HDL-C), triglycerides (TGs), fasting blood sugar (FBS), systolic blood pressure (SBP) and diastolic blood pressure (DBP) as continuous traits after adjusting for age and gender were 27, 46, 36, 29, 25, 26 and 15%, respectively, and MSS had a heritability of 15%. When MetS components were analysed as discrete traits, the estimates of age and gender adjusted heritability for MetS, abdominal obesity, low HDL-C, high TG, high FBS and high blood pressure (BP) were 22, 40, 34, 38 and 23%, respectively (P < 0·05). Three factors were extracted from the six continuous traits of the MetS including factor I (BP), factor II (lipids) and factor III (obesity and FBS). Heritability estimation for these three factors were 7, 13 (P < 0·05) and 2%, respectively. The highest heritability was for HDL-C and TG. The results strongly encourage efforts to identify the underlying susceptibility genes.

CpG Island Methylation of the Rap1Gap Gene in Medullary Thyroid Cancer.

BACKGROUND: Medullary thyroid cancer (MTC) is a rare type of neuroendocrine tumor. This study aimed to investigate the gene and protein expression of RAP1GAP and DNA methylation patterns of its CpG74a , CpG74b , and CpG24 in an Iranian population with MTC. METHODS: In this case-control study, we selected 55 individuals who underwent thyroidectomy in Erfan hospital, Tehran, between 2018 and 2020. Samples were divided into normal thyroid tissues (control; n=20), benign nodule (n=20), and MTC (n=15). DNA methylation patterns were investigated using MSP (methylation-specific PCR). The protein level and mRNA expression of RAP1GAP were also evaluated using western blotting and real-time PCR, respectively. RESULTS: The hyper-methylation rates of CpG24 and CpG74a in the MTC samples were considerably higher than the controls (83% versus 15% and 74% versus 17%, respectively; P<0.001). The methylation/unmethylation ratio of CpG74a , and CpG24 was considerably higher than the controls (P<0.001). The methylation/unmethylation ratio of CpG24 in the benign nodules was also considerably greater than the controls (P<0.001). The mRNA expression and the protein level of RAP1GAP in the MTC group were considerably lower than the controls (P=0.005 and P=0.035, respectively). In the MTC group, aberrant methylation of CpG74a and CpG24 was significantly correlated with decreasing expression of the Rap1Gap gene (R2 : 0.23; P=0.032 and R2 : 0.56; P=0.001, respectively). CONCLUSION: Hyper-methylation in CpG24 and CpG74a and decreasing expression of RAP1GAP can be considered as diagnostic biomarkers for MTC.

Comparing Oxidative Stress Status Among Iranian Males and Females with Malignant and Non-malignant Thyroid Nodules.

BACKGROUND: Oxidative stress is commonly accrued in thyroid tissue during hormone synthesis. OBJECTIVES: We aimed to examine oxidative stress in patients with thyroid cancer, benign thyroid nodules, and healthy individuals. METHODS: In this study, 138 individuals were involved. Among the selected participants, 108 had thyroid nodules, including 30 papillary thyroid cancer (PTC), 30 follicular thyroid cancer (FTC), six anaplastic thyroid cancer (ATC), 12 medullary thyroid cancer (MTC), and 30 benign nodules. In addition, 30 individuals were selected as a healthy control group. The levels of total antioxidant capacity (TAC) and total oxidant status (TOS) of thyroid tissue were measured using the ELISA method, and the oxidative stress index (OSI) was calculated. RESULTS: The TAC level was significantly lower in MTC and FTC subtypes than in controls. The TOS level was considerably higher in the MTC group than in the control and benign nodule groups. The TOS level was not changed in other groups. The OSI was considerably higher in MTC and FTC subtypes. The TAC and OSI in benign nodules were significantly lower and higher than those of controls, respectively. The OSI was higher in female patients than in males. CONCLUSIONS: The OSI can not be considered a diagnostic biomarker for benign nodules and MTC. The diverse oxidative stress status between genders may be related to the elevated cancer incidence in females.

Biochemical Assessment: Findings from 20 Years of the Tehran Lipid and Glucose Study.

CONTEXT: The Tehran Lipid and Glucose Study (TLGS) is a community-based study to reveal the frequency of non-communicable diseases (NCDs) in Tehran's population. This research consists of two main parts, a cross-sectional study on the prevalence of cardiovascular risk factors and a 20-year-ongoing prospective cohort study, which was initiated in 1999 in several phases with an approximate duration of 3.6 years, and is still ongoing. The aim of the present study is review the 20 year biochemical findings of the TLGS related to the NCDs in a large sample. METHODS: All articles on biochemical assessments derived from the TLGS from the earliest publications (2002) until 30 January 2018 were reviewed for their findings on different risk factors of NCDs. RESULTS: According to the TLGS findings high sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), homocysteine (Hcy), age, smoking, hypertension, and obesity were the most important risk factors of cardiovascular diseases (CVD). It was illustrated that in subjects with abdominal obesity, the hs-CRP and IL-6 serum levels were higher than in normal subjects. The most appropriate prognostic indexes and associations were for hs-CRP, IL-6, and Hcy with abdominal obesity, waist circumference, WHtR, and wrist circumference, respectively. Previous studies have demonstrated a direct relationship between obesity and serum levels of inflammatory factors. CONCLUSIONS: According to the results of TLGS, serum levels of biochemical risk factors such as hs-CRP, IL-6, and Hcy could be beneficial in early diagnosis and effective treatment of cardiovascular, obesity and other metabolic diseases.

Epigenetic modifications in human thyroid cancer.

Thyroid carcinoma is the most common endocrine malignancy of the endocrine organs, and its incidence rate has steadily increased over the last decade. Over 95% of thyroid carcinoma is derived from follicular cells that have a spectrum of differentiation to the most invasive malignancy. The molecular pathogenesis of thyroid cancer remains to be clarified, although activating the RET, RAS and BRAF oncogenes have been well characterized. Increasing evidence from previous studies demonstrates that acquired epigenetic abnormalities participating with genetic alteration results in altered patterns of gene expression/function. Aberrant DNA methylation has been established in the CpG regions and microRNAs (miRNAs) expression profile recognized in cancer development. In the present review, a literature review was performed using MEDLINE and PubMed with the terms 'epigenetic patterns in thyroid cancer [or papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), medullary thyroid cancer (MTC), anaplastic thyroid cancer (ATC)]', 'DNA methylation in thyroid cancer (or PTC, FTC, MTC, ATC)', 'miRNA expression in thyroid cancer (or PTC, FTC, MTC, ATC)', 'epigenetic patterns in cancer' and the current understanding of epigenetic patterns in thyroid cancer was discussed.

The association between inflammatory markers and obesity-related factors in Tehranian adults: Tehran lipid and glucose study.

OBJECTIVES: Obesity considered being a low-grade inflammatory disease. The objective of this study was to examine the association between inflammatory markers (IM) including C-reactive protein (hs-CRP), Interleukin-6 (IL-6), and homocystein (Hcy) and obesity-related factors (e.g. BMI, waist, hip) in adult participants of Tehran lipid and glucose study (TLGS). MATERIALS AND METHODS: In this cross-sectional study, 352 individuals (132 men and 220 women), age ≥19 years, were randomly recruited from participants of TLGS population. The serum levels of hs-CRP, IL-6, Hcy were determined using the enzyme linked immunosorbent assay (ELISA) method. Variables were compared by sample t-test. Bivariate linear correlation was estimated using Pearson's correlation coefficient. Linear regression analysis was applied to investigate the association between IMs and anthropometric and biochemical variables. RESULTS: The mean age of participants was 46.1±16.1 years. abdominal obesity was present in 199(56.5%) individuals. levels of hs-CRP and IL-6 increased in the abdominally obese group (1507±3.3 vs. 577.8±4.3 ng/ml P<0.001) (3.6±3.3 vs. 1.9±3.8 pg/ml P< 0.001), and in the same group, the best predictors for hs-CRP, IL-6 and Hcy were waist (WC), waist to height ratio (WHtR) and wrist respectively; hip and WHtR were the best predictors for Hcy and hs-CRP in the normal group. A linear augmentation in hs-CRP and IL-6 levels was observed in association with obesity categorizes. CONCLUSION: This study provides evidence that abdominally obese individuals had higher levels of IMs. Wrist, waist and WHtR were the best predictors for Hcy, hs-CRP and IL-6 respectively in this group.

Association between TPO gene polymorphisms and Anti-TPO level in Tehranian population: TLGS.

INTRODUCTION: Thyroid peroxidase (TPO) gene variations are one cause of thyroid autoimmune diseases. The aim of this study was to examine the association between the T1936C, T2229C and A2257C polymorphisms of the TPO gene and Anti-TPO level. MATERIALS AND METHODS: In this case-control study, 188 individuals (86 males and 102 females), aged 20-80 years, were randomly selected from among the Tehran Lipid and Glucose Study (TLGS) population. A2257C and T2229C SNPs were detected with RFLP by use of BsrI and Eco57I as the restriction enzymes respectively, while the T1936C SNP was determined with ARMS-PCR. RESULTS: In the presence of the C allele of T1936C, Anti-TPO level was significantly increased (CC: 238±43.3, CT: 47.7±15.9, TT: 74.1±11.3 IU/L p=0.002); however, this association was attenuated after adjustment for sex and age (p=0.059). No significant difference, before and after adjustment, was found in Anti-TPO level in the presence of T2229C SNP (CC: 129.1±24.5, CT: 43.5±12.6, TT: 126.5±13.8 IU/L p=0.196). The association between A2257C and Anti-TPO level was only significant after adjustment for potential confounders (p=0.007). The association between ATC and CTT haplotypes and Anti-TPO level was significant (p=0.023, 0.021 respectively), the association between CTT and Anti-TPO concentration was also significant after adjustment for sex (p=0.014). CONCLUSION: The results of the present study confirmed the association between TPO gene polymorphisms and Anti-TPO level in the Tehranian population.

The relationship between metabolic syndrome, cardiometabolic risk factors and inflammatory markers in a Tehranian population: the Tehran Lipid and Glucose Study.

OBJECTIVE: The aim of this study was to investigate the relationship between the high sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6) and homocysteine (Hcy) levels and cardiometabolic risk factors in subjects with and without metabolic syndrome (MetS) in a sample of the Tehranian population. METHODS: In this cross-sectional study, 365 individuals aged ≥ 19 years were randomly selected from among participants of the Tehran Lipid and Glucose Study (TLGS). The serum levels of IL-6, hsCRP and Hcy were determined using the Enzyme Linked Immunosorbent Assay (ELISA) method. RESULTS: Of the 365 subjects, aged a mean of 46.1 ± 16.1 years, MetS was present in 160 (43.8%) individuals. The levels of hsCRP, Hcy and IL-6 were higher in the subjects with MetS. A gradual and significant increase in the levels of hsCRP was found in association with increasing numbers of MetS components after adjusting for sex and age. A strong linear augmentation in the hsCRP levels was observed as the numbers of MetS components increased. Additionally, an increase of 0.40 was observed in the hsCRP levels in association with increases in each component of MetS adjusted for age and sex. The best predictors for the levels of hsCRP, IL-6 and Hcy in the subjects with MetS were hip, waist to height ratio (WHtR) and height, respectively. CONCLUSION: Hip and WHtR are significant predictors of elevated levels of hsCRP and IL-6 associated with MetS, respectively.

Is there any association of apolipoprotein E gene polymorphism with obesity status and lipid profiles? Tehran Lipid and Glucose Study (TLGS).

AIMS: Considering the key role played by the apolipoprotein E (Apo E) gene in the regulation of lipid metabolism and obesity, the current study has evaluate the association between abdominal obesity and Apo E gene polymorphism in a population of Tehran. MATERIALS AND METHODS: A cross-sectional study was performed on 345 men and 498 women, aged 19-86 years, selected from among participants of the Tehran Lipid and Glucose Study. The RFLP-PCR technique was employed to investigate polymorphism in the gene fragments. Based on the national survey of risk factors for non-communicable diseases of Iran, waist circumference (WC) cut off was set at 89 cm for men and 91 cm for women. The risk effect of obesity related variables and lipid profiles in two groups of WC were examined by logistic regression. For body mass index (BMI), waist to hip ratio (WHR), high-density lipoprotein-cholesterol (HDL-C), triglyceride (TG), fasting blood sugar (FBS), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and blood pressure (BP), the standard risk cut-offs were applied. RESULTS: Frequencies of E2, E3, and E4 alleles were 9.7, 73, and 14.6%, respectively. The presence of the E3 allele was significantly associated with higher TG level in subjects with high WC, while, the presence of E4 allele decreased the plasma HDL-C (E2:52.1±13.1 vs., E3:48.9±11.2 vs., E4:44.6±10.6 mg/dl, p<0.05), HDL-C2 (E2:20.4±9.2 vs., E3:19.1±8.8 vs., E4:16.3±7.9 mg/dl, p<0.05), and HDL-C3 (E2:32.1±7.4 vs., E3:30.3±6.2 vs., E4:28.3±6.1 mg/dl, p<0.05) in normal WC subjects. The presence of the E3 carrier increased the risk of having higher plasma TG, compared with the E2 carrier (95% CI OR=1.91, 1.02-3.57; p=0.04). CONCLUSION: According to the results of this study, the E3 carrier, caused an approximately 90% increase in the levels of TG in the group with abdominal obesity.

Association of CD36 gene variants and metabolic syndrome in Iranians.

AIMS: The CD36 gene encodes for a membrane receptor that facilitates fatty-acid uptake and utilization. Genetic variants of the CD36 gene have been associated with metabolic syndrome (MetS). We aimed to evaluate the association between the rs10499859A>G and rs13246513C>T polymorphisms and MetS components. METHODS: For this case-control study, 140 MetS and 187 normal subjects were randomly selected from the Tehran Lipid and Glucose Study participants. Biochemical and anthropometrical variables were measured. Genotyping for both single nucleotide polymorphisms (SNPs) was performed by polymerase chain reaction-restriction fragment length polymorphism. RESULTS: Case and control groups were not different in allele and genotype frequencies for these SNPs. However, the A and T alleles of these SNPs were significantly associated with elevated levels of high-density lipoprotein cholesterol (HDL-C) before age and sex adjustment (p=0.027 and 0.016, respectively). Association between the A allele and body mass index (BMI) was also significant after adjustment for MetS under the dominant model (p=0.009, ß(2)=0.68). CONCLUSIONS: Based on our results, these polymorphisms do affect HDL-C level and BMI (MetS components), although the effect may be slight and restricted specifically to an environment-genotype.

Haplotype analysis of Apo AI-CIII-AIV gene cluster and lipids level: Tehran Lipid and Glucose Study.

Iranian populations show an increased tendency for abnormal lipid levels and high risk of Coronary artery disease. Considering the important role played by the ApoAI-CIII-AIV gene cluster in the regulation of the level and metabolism of lipids, this study aimed at elucidating the association between five single nucleotide polymorphisms on the Apo11q cluster gene and lipid levels. A cross-sectional study of 823 subjects (340 males and 483 females) from the Tehran lipid and glucose study (TLGS) was conducted. Levels of TG, Chol, HDL-C, Apo AI, Apo AIV, Apo B, and Apo CIII were measured, and the selected segments of the APOAI-CIII-AIV gene cluster were amplified by PCR and the polymorphisms were revealed by RFLP using restriction enzymes. The allele frequencies for each SNP between males and females were not significantly different. The distribution of Genotypes and alleles was in Hardy-Weinberg equilibrium except for Apo AI (+83C>T). The results showed a significant association between TG, HDL-C, HDL(2), Apo AI, and Apo B levels and the presence of some alleles in the polymorphisms studied. After haplotype analysis not only did the association between these variables and SNPs remain but also levels of Chol and LDL-C were added. This study demonstrates that the level of lipids such as TG, HDL-C, HDL(2), Apo AI, and Apo B, maybe regulated partly by genetic factors and their haplotype within the Apo11q gene cluster.