Polymorphism of peroxisome proliferator-activated receptor γ (PPARγ) Pro12Ala in the Iranian population: relation with insulin resistance and response to treatment with pioglitazone in type 2 diabetes

Unveiling clinically significant PPARγ mutations for thiazolidinedione treatment responsiveness through atomistic simulations

In Type 2 diabetes, increased insulin sensitivity is induced by thiazolidinedione activation of the peroxisome proliferator-activated receptor gamma (PPARγ). Recent data indicate a relationship between SNPs in PPARγ and poor drug response. Therefore, understanding the pathogenic consequences of mutations in PPARγ-mediated protein-drug interactions will be prima-facie for establishing personalized medicine. The PPARG gene has 197 missense SNPs, 22 of which were determined to be both deleterious and destabilizing, employing in silico approaches. Molecular docking analysis suggested that the mutation influenced the binding energy of at least seven of the variants. The mutant R316H was identified as the most damaging and deleterious from the observed results. For a better understanding of the dynamic variation upon mutation at the atomic level, molecular dynamics simulations of the wild-type and R316H mutant PPARγ structure were performed. The analysis indicates that the mutation increased protein structural compactness while decreasing flexibility. The reduced dynamics in the mutant structure was further validated by principal component analysis. This mechanistic evaluation of the PPARγ protein variants provides insight into the relationship between genetic variation and interindividual variability of drug responsiveness and will facilitate the future studies for the development of tailored treatment regime for precision medicine.

Correlation between PPARG Pro12Ala Polymorphism and Therapeutic Responses to Thiazolidinediones in Patients with Type 2 Diabetes: A Meta-Analysis

Background: Thiazolidinediones (TZDs) are a type of oral drug that are utilized for the treatment of type 2 diabetes mellitus (T2DM). They function by acting as agonists for a nuclear transcription factor known as peroxisome proliferator-activated receptor-gamma (PPAR-γ). TZDs, such as pioglitazone and rosiglitazone, help enhance the regulation of metabolism in individuals with T2DM by improving their sensitivity to insulin. Previous studies have suggested a relationship between the therapeutic efficacy of TZDs and the PPARG Pro12Ala polymorphism (C > G, rs1801282). However, the small sample sizes of these studies may limit their applicability in clinical settings. To address this limitation, we conducted a meta-analysis assessing the influence of the PPARG Pro12Ala polymorphism on the responsiveness of TZDs. Method: We registered our study protocol with PROSPERO, number CRD42022354577. We conducted a comprehensive search of the PubMed, Web of Science, and Embase databases, including studies published up to August 2022. We examined studies investigating the association between the PPARG Pro12Ala polymorphism and metabolic parameters such as hemoglobin A1C (HbA1C), fasting plasma glucose (FPG), triglyceride (TG), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and total cholesterol (TC). The mean difference (MD) and 95% confidence intervals (CIs) between pre- and post-drug administration were evaluated. The quality of the studies included in the meta-analysis was assessed by using the Newcastle-Ottawa Scale (NOS) tool for cohort studies. Heterogeneity across studies was assessed by using the I2 value. An I2 value greater than 50% indicated substantial heterogeneity, and a random-effects model was used for meta-analysis. If the I2 value was below 50%, a fixed-effects model was employed instead. Both Begg's rank correlation test and Egger's regression test were performed to detect publication bias, using R Studio software. Results: Our meta-analysis incorporated 6 studies with 777 patients for blood glucose levels and 5 studies with 747 patients for lipid levels. The included studies were published between 2003 and 2016, with the majority involving Asian populations. Five of the six studies utilized pioglitazone, while the remaining study employed rosiglitazone. The quality scores, as assessed with the NOS, ranged from 8 to 9. Patients carrying the G allele exhibited a significantly greater reduction in HbA1C (MD = -0.3; 95% CI = -0.55 to -0.05; p = 0.02) and FPG (MD = -10.91; 95% CI = -19.82 to -2.01; p = 0.02) levels compared to those with the CC genotype. Furthermore, individuals with the G allele experienced a significantly larger decrease in TG levels than those with the CC genotype (MD = -26.88; 95% CI = -41.30 to -12.46; p = 0.0003). No statistically significant differences were observed in LDL (MD = 6.69; 95% CI = -0.90 to 14.29; p = 0.08), HDL (MD = 0.31; 95% CI = -1.62 to 2.23; p = 0.75), and TC (MD = 6.4; 95% CI = -0.05 to 12.84; p = 0.05) levels. No evidence of publication bias was detected based on Begg's test and Egger's test results. Conclusions: This meta-analysis reveals that patients with the Ala12 variant in the PPARG Pro12Ala polymorphism are more likely to exhibit positive responses to TZD treatment in terms of HbA1C, FPG, and TG levels compared to those with the Pro12/Pro12 genotype. These findings suggest that genotyping the PPARG Pro12Ala in diabetic patients may be advantageous for devising personalized treatment strategies, particularly for identifying individuals who are likely to respond favorably to TZDs.

Current progress in pharmacogenomics of Type 2 diabetes: A systemic overview

INTRODUCTION

Type 2 diabetes mellitus (T2DM) is a prevalent disease with incidences increasing globally at a rapid rate. The goal of T2DM treatment is to control glucose levels and prevent the aggravation of glycemic symptoms.

TREATMENT OPTIONS

T2DM regimen include metformin as the first-line, with sulfonylurea, thiazolidinedione (TZD), GLP-1, DPP4I, and SGLT2 inhibitor as the second-line treatment options. However, even with a multitude of choices, patient-to-patient variability due to pharmacogenomic differences still prevail.

CONCLUSION

This review aims to discuss the responses of the major T2DM medications influenced by pharmacogenomics and investigate improved personalized therapy for T2DM patients.

Polymorphic genetic markers and how they are associated with clinical and metabolic indicators of type 2 diabetes mellitus in the Kazakh population

Background

Type 2 diabetes mellitus is a serious public health problem worldwide. The aim of the study was to analyze the relationship of eight polymorphic gene variants with the development of clinical-metabolic rates of type 2 diabetes mellitus inside Kazakh population.

Materials and methods

139 patients with type 2 diabetes mellitus and 100 patients in the control group were examined. Genotyping of polymorphisms of candidate genes was carried out on a next generation QuantStudio 12 K Flex unit.

Results

Gene TCF7L2 locus rs7901695 and rs7903146, gene KCNQ1 locus rs2237892, rs7756992, and gene CDKAL1 locus rs7754840 demonstrated statistically significant associations with glucose metabolism, lipid profile and body mass index (BMI) in type 2 DM inside the population. Statistically significant difference in anthropometric and biochemical measures of rs17584499, rs4712523 and rs163184 has not been revealed.

Conclusions

Genetic polymorphisms that influence pancreatic gland beta-cells insulin release and secretion associate with metabolic and anthropometric measures definitive for type 2 DM in Kazakh population.

Pharmacogenomic Studies of Current Antidiabetic Agents and Potential New Drug Targets for Precision Medicine of Diabetes

Diabetes is a major threat to people's health and has become a burden worldwide. Current drugs for diabetes have limitations, such as different drug responses among individuals, failure to achieve glycemic control, and adverse effects. Exploring more effective therapeutic strategies for patients with diabetes is crucial. Currently pharmacogenomics has provided potential for individualized drug therapy based on genetic and genomic information of patients, and has made precision medicine possible. Responses and adverse effects to antidiabetic drugs are significantly associated with gene polymorphisms in patients. Many new targets for diabetes also have been discovered and developed, and even entered clinical trial phases. This review summarizes pharmacogenomic evidence of some current antidiabetic agents applied in clinical settings, and highlights potential drugs with new targets for diabetes, which represent a more effective treatment in the future.

PPARG (Pro12Ala) genetic variant and risk of T2DM: a systematic review and meta-analysis

Type 2 diabetes mellitus (T2DM) is a complex disease caused by the interaction between genetic and environmental factors. A growing number of evidence suggests that the peroxisome proliferator-activated receptor gamma (PPARG) gene plays a major role in T2DM development. Meta-analysis of genetic association studies is an efficient tool to gain a better understanding of multifactorial diseases and potentially to provide valuable insights into gene-disease interactions. The present study was focused on assessing the association between Pro12Ala variation in the PPARG and T2DM risk through a comprehensive meta-analysis. We searched PubMed, WoS, Embase, Scopus and ProQuest from 1990 to 2017. The fixed-effect or random-effect model was used to evaluate the pooled odds ratios (ORs) and 95% confidence intervals (CIs) depending on the heterogeneity among studies. The sources of heterogeneity and publication bias among the included studies were assessed using I² statistics and Egger's tests. A total of 73 studies, involving 62,250 cases and 69,613 controls were included. The results showed that the minor allele (G) of the rs1801282 variant was associated with the decreased risk of T2DM under different genetic models. Moreover, the protective effect of minor allele was detected to be significantly more in some ethnicities including the European (18%), East Asian (20%), and South East Asian (18%). And the reduction of T2DM risk in Ala12 carriers was stronger in individuals from North Europe rather than Central and South Europe. Our findings indicated that the rs1801282 variant may contribute to decrease of T2DM susceptibility in different ancestries.

PPARA, PPARD and PPARG gene polymorphisms in patients with unstable angina

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) include the nuclear receptor superfamily of ligand-activated transcription factors involved in several metabolic processes, including carbohydrate and lipid metabolism.

MATERIAL AND METHODS

In this study we examined PPARA: rs4253778, rs1800206, PPARD: rs2267668, rs2016520, rs1053049, PPARG rs1801282 and PPARGC1A rs8192678 polymorphisms in patients with unstable angina. This study included 246 patients with unstable angina confirmed by coronary angiography (defined by >70% stenosis in at least one major coronary artery) and 189 healthy controls.

RESULTS

We observed statistically significant difference in distribution of PPARG rs1801282 genotypes and alleles between patients and control group. Among patients there was the increased frequency of CG and GG genotypes and G alleles. The association between PPARG rs1801282 G allele and unstable angina was confirmed in multivariate regression analysis. There were no statistically significant differences in the distributions of other studied polymorphisms between patients with unstable angina and the control group.

CONCLUSIONS

The results of our study suggest the association between PPARG rs1801282 G allele and unstable angina in Polish population.

Adjuvant Effect of Molecular Iodine in Conventional Chemotherapy for Breast Cancer. Randomized Pilot Study

This study analyzes an oral supplement of molecular iodine (I₂), alone and in combination with the neoadjuvant therapy 5-fluorouracil/epirubicin/cyclophosphamide or taxotere/epirubicin (FEC/TE) in women with Early (stage II) and Advanced (stage III) breast cancer. In the Early group, 30 women were treated with I₂ (5 mg/day) or placebo (colored water) for 7–35 days before surgery. For the Advanced group, 30 patients received I₂ or placebo, along with FEC/TE treatment. After surgery, all patients received FEC/TE + I₂ for 170 days. I₂ supplementation showed a significant attenuation of the side effects and an absence of tumor chemoresistance. The control, I₂, FEC/TE, and FEC/TE + I₂ groups exhibited response rates of 0, 33%, 73%, and 100%, respectively, and a pathologic complete response of 18%, and 36% in the last two groups. Five-year disease-free survival rate was significantly higher in patients treated with the I₂ supplement before and after surgery compared to those receiving the supplement only after surgery (82% versus 46%). I₂-treated tumors exhibit less invasive potential, and significant increases in apoptosis, estrogen receptor expression, and immune cell infiltration. Transcriptomic analysis indicated activation of the antitumoral immune response. The results led us to register a phase III clinical trial to analyze chemotherapy + I₂ treatment for advanced breast cancer.

Influence of LRP5 (rs556442) polymorphism on insulin resistance in healthy Iranian children and adolescents

Background/aim

Genetic aspects play a role in insulin resistance in children. In this study, for the first time, the association of LRP5 (rs556442) polymorphism and insulin resistance in Iranian children and adolescents was investigated.

Materials and methods

The study population comprises children and adolescents aged 9–18 years. Anthropometric and biochemical parameters were assessed. Insulin resistance/sensitivity was determined by the quantitative insulin sensitivity check index (QUICKI), homeostasis model assessment-insulin resistance (HOMA-IR), insulin-to-glucose ratio, McAuley index, revised McAuley index, fasting insulin resistance index (FIRI), and Bennett’s index. LRP5 (rs566442) single nucleotide polymorphism (SNP) was identified using restriction fragment length polymorphism (RFLP). Linear regression analysis was used to determine the association between the LRP5 polymorphism (rs556442) and insulin sensitivity indexes.

Results

Significant differences were found between GG genotype vs. AG/AA genotypes for McAuley index (P = 0.049) and revised McAuley index (P = 0.044) when adjusted for interaction factors (age, sex, and puberty) in regression models. No significant association was found between LRP5 (rs566442) and other insulin resistance indexes. Also, LRP5 (rs566442) did not show a significant impact on biochemical parameters.

Conclusion

This study showed that LRP5 polymorphism (rs556442) was associated with insulin resistance in Iranian children and adolescents.

Pharmacogenetics of type 2 diabetes mellitus, the route toward tailored medicine

Type 2 diabetes mellitus (T2DM) is a chronic disease that has reached the levels of a global epidemic. In order to achieve optimal glucose control, it is often necessary to rely on combination therapy of multiple drugs or insulin because uncontrolled glucose levels result in T2DM progression and enhanced risk of complications and mortality. Several antihyperglycemic agents have been developed over time, and T2DM pharmacotherapy should be prescribed based on suitability for the individual patient's characteristics. Pharmacogenetics is the branch of genetics that investigates how our genome influences individual responses to drugs, therapeutic outcomes, and incidence of adverse effects. In this review, we evaluated the pharmacogenetic evidences currently available in the literature, and we identified the top informative genetic variants associated with response to the most common anti-diabetic drugs: metformin, DPP-4 inhibitors/GLP1R agonists, thiazolidinediones, and sulfonylureas/meglitinides. Overall, we found 40 polymorphisms for each drug class in a total of 71 loci, and we examined the possibility of encouraging genetic screening of these variants/loci in order to critically implement decision-making about the therapeutic approach through precision medicine strategies. It is possible then to anticipate that when the clinical practice will take advantage of the genetic information of the diabetic patients, this will provide a useful resource for the prevention of T2DM progression, enabling the identification of the precise drug that is most likely to be effective and safe for each patient and the reduction of the economic impact on a global scale.

Expert consensus on clinical assessment and intervention of vascular aging in China (2018)

With the development of geriatric medicine, more and more reported research has found that as humans grow old, their blood vessels also age. Blood vessels are vital components of various organs. Vascular aging is an important physiological and pathological basis for the aging of organs and systems of the human body and is the common pathogenesis of various chronic diseases in the elderly. Early detection of vascular aging and the use of correct methods to delay and treat vascular aging are of great significance to prevent and control chronic diseases in the elderly and to deal with the increasingly serious problems of population aging. For this purpose, this consensus is formulated for use by geriatric doctors and related personnel.

Beneficial effects of n-3 polyunsaturated fatty acids on adiponectin levels and AdipoR gene expression in patients with type 2 diabetes mellitus: a randomized, placebo-controlled, double-blind clinical trial

INTRODUCTION

There is evidence that n-3 polyunsaturated fatty acids (n-3 PUFAs) exert beneficial effects to improve type 2 diabetes mellitus (T2DM), but its complications remain poorly understood. Hypoadiponectinemia is one of the important mechanisms responsible for T2DM which necessitates developing novel therapeutic strategies. We aimed to determine the effect of n-3 PUFA supplementation on circulating adiponectin and mRNA expression of adiponectin receptors (AdipoR1, AdipoR2) and Sirt-1 in T2DM patients.

MATERIAL AND METHODS

A randomized, double-blind, placebo-controlled trial of 10-week follow-up of n-3 PUFAs (2.7 g/day) vs. placebo in T2DM patients (n = 88) was conducted. In detail, T2DM patients (n = 44) were treated with n-3 PUFAs and the remainder received placebo. Anthropometric and metabolic characteristics were assessed in all participants. Circulating level of adiponectin and mRNA expression of AdipoR1, AdipoR2 and Sirt-1 were measured in peripheral blood mononuclear cells (PBMC) using real-time polymerase chain reaction before and after the intervention.

RESULTS

It was found that n-3 PUFAs increased AdipoR1 gene expression (fold change = 1.321 in n-3 PUFAs vs. 1.037 in placebo) and AdipoR2 mRNA (fold change = 1.338 in n-3 PUFAs vs. 1.034 in placebo). No significant changes were observed for Sirt-1 expression. The serum level of adiponectin significantly (p = 0.035) increased in n-3 PUFAs (5.09 to 5.58 μg/ml) but remained unchanged in the placebo group.

CONCLUSIONS

Daily supplementation with n-3 PUFAs (2.7 g) was effective to significantly improve gene expression of AdipoR1 and AdipoR2 and the serum level of adiponectin in T2DM patients. Therefore, n-3 PUFAs might emerge as an adjuvant for current antidiabetic therapies. However, confirmatory long-term studies are required.

Genotype Phenotype Correlation of Genetic Polymorphism of PPAR Gamma Gene and Therapeutic Response to Pioglitazone in Type 2 Diabetes Mellitus- A Pilot Study

INTRODUCTION

Pro12Ala polymorphism is a missense mutation at codon 12 in peroxisome proliferator-activated receptor γ gene (PPARG). This polymorphism is known to be associated with increased insulin sensitivity. Pioglitazone, a thiazolidinedione, is an anti-diabetic drug which acts as an agonist at PPAR γ receptor.

AIM

To determine the association between Pro12Ala polymorphism of the PPARG and variation in therapeutic response to the PPARγ agonist, pioglitazone.

MATERIALS AND METHODS

The study was done as a hospital based pilot project in 30 patients with type 2 diabetes mellitus, on treatment with sulfonylurea or metformin but without adequate glycaemic control. They were started on pioglitazone as add on therapy for a period of 12 weeks. The participants were categorized as responders and non-responders based on the change in HbA1C level after 12 weeks. Pro12Ala polymorphism was analysed by polymerase chain reaction-restriction fragment length polymorphism.

STATISTICAL ANALYSIS

Logistic regression analysis was done to evaluate the associations between age, baseline body weight, BMI, waist circumference, waist-hip ratio and Pro12Ala variants with the response to pioglitazone. The p-value< 0.05 was considered significant.

RESULTS

The frequency distributions of PPAR gamma genotypes were 80% for Pro/Pro and 20% for Pro/Ala in the study population. Among the study participants, 30% were non-responders and 70% responders to pioglitazone. A significantly higher frequency of the polymorphism was detected in the responders (p=0.005) compared to non-responders group.

CONCLUSION

Our study suggests that there is a potential association between Pro12Ala polymorphism and glycaemic response to pioglitazone.

Association between Genetic Variants and Diabetes Mellitus in Iranian Populations: A Systematic Review of Observational Studies

INTRODUCTION

Diabetes mellitus as the most prevalent metabolic disease is a multifactorial disease which is influenced by environmental and genetic factors. In this systematic review, we assessed the association between genetic variants and diabetes/its complications in studies with Iranian populations.

METHODS

Google Scholar, PubMed, Scopus, and Persian web databases were systematically searched up to January 2014. The search terms were "gene," "polymorphism," "diabetes," and "diabetic complications"; nephropathy, retinopathy, neuropathy, foot ulcer, and CAD (coronary artery diseases); and Persian equivalents. Animal studies, letters to editor, and in vitro studies were excluded.

RESULTS

Out of overall 3029 eligible articles, 88 articles were included. We found significant association between CTLA-4, IL-18, VDR, TAP2, IL-12, and CD4 genes and T1DM, HNFα and MODY, haptoglobin, paraoxonase, leptin, TCF7L2, calreticulin, ERα, PPAR-γ2, CXCL5, calpain-10, IRS-1 and 2, GSTM1, KCNJ11, eNOS, VDR, INSR, ACE, apoA-I, apo E, adiponectin, PTPN1, CETP, AT1R, resistin, MMP-3, BChE K, AT2R, SUMO4, IL-10, VEGF, MTHFR, and GSTM1 with T2DM or its complications.

DISCUSSION

We found some controversial results due to heterogeneity in ethnicity and genetic background. We thought genome wide association studies on large number of samples will be helpful in identifying diabetes susceptible genes as an alternative to studying individual candidate genes in Iranian populations.

Stratified medicine for the use of antidiabetic medication in treatment of type II diabetes and cancer: where do we go from here?

At present, the global diabetes epidemic is affecting 347 million individuals, 90% of whom are diagnosed with type II diabetes mellitus (T2DM). T2DM is commonly treated with more than one type of therapy, including oral antidiabetic drugs (OADs) and agents used in the treatment of diabetic complications. Several pharmacological classes of OADs are currently available for the treatment of T2DM, of which insulin secretagogues (i.e. sulphonylureas and meglitinides), insulin sensitizers [thiazolidinediones (TZDs)] and biguanides are the most commonly prescribed. Although many of these OADs have been used for more than half a century in the treatment of T2DM, the pharmacogenomic characteristics of these compounds have only recently been investigated, primarily in retrospective studies. Recent advances in pharmacogenomics have led to the identification of polymorphisms that affect the expression and function of drug-metabolizing enzymes and drug transporters, as well as drug targets and receptors. These polymorphisms have been shown to affect the therapeutic response to and side effects associated with OADs. The aim of this review was to provide an up-to-date summary of some of the pharmacogenomic data obtained from studies of T2DM treatment, with a focus on polymorphisms in genes affecting pharmacokinetics, pharmacodynamics and treatment outcome of the most commonly prescribed OADs. In addition, the implications of pharmacogenomics in the use of the OAD metformin in cancer will be briefly discussed. Finally, we will focus on recent advances in novel 'omics' technologies and discuss how these might aid in the personalized management of T2DM.

Docosahexaenoic Acid-Rich Fish Oil Supplementation Improves Body Composition without Influence of the PPAR&#947; Pro12Ala Polymorphism in Patients with Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

<b><i>Background:</i></b> The aims of this research were to investigate (1) the impact of docosahexaenoic acid (DHA)-rich fish oil supplementation on body composition, plasma adiponectin level, and peroxisome proliferator-activated receptor &#947; (PPAR&#947;) gene expression, and (2) whether the effect of DHA-rich fish oil supplementation on the aforementioned variables is modulated by PPAR&#947; Pro12Ala polymorphism. <b><i>Methods:</i></b> We genotyped PPAR&#947; Pro12Ala polymorphism in subjects with type 2 diabetes mellitus (T2DM). Ala carriers and non-Ala carriers were randomly assigned to DHA-rich fish oil or placebo intake for 8 weeks. <b><i>Results:</i></b> Glycemic control was not affected by the intervention. The supplementation with DHA-rich fish oil decreased waist circumference (p < 0.001), body fat mass (p = 0.01), body fat percent (p = 0.04), and visceral fat rating (p = 0.02) as well as trunk fat mass (p = 0.04). Weight, body mass index, fat-free mass, adiponectin level, and PPAR&#947; gene expression changes showed no significant difference. No gene-diet interaction was found on body composition, adiponectin level, and PPAR&#947; gene expression. <b><i>Conclusions:</i></b> DHA-rich fish oil supplementation favorably modulated body composition in patients with T2DM and could be useful to reduce visceral obesity. However, the PPAR&#947; Pro12Ala polymorphism did not influence the changes in the desired variables.

Patient profiling in diabetes and role of canagliflozin

Background

Physicians attempt to achieve glycemic goals in patients with type 2 diabetes mellitus (T2DM) through various means, including glucose-lowering medications. There is interindividual variability in response to medications, which can be partially explained by the presence of genetic polymorphisms that affect drug metabolism. Pharmacogenomics studies the hereditary basis of interpatient variations in drug response and aims to identify subgroups of patients whose drug management could be tailored accordingly. The aim of this review is to explore patient profiling in the management of T2DM with a focus on the sodium glucose transporter inhibitor canagliflozin.

Methods

The PubMed database was searched using the terms “pharmacogenomics” and “diabetes” through May 31, 2014. Published articles and abstracts presented at national/international meetings were considered.

Results and conclusion

Genome-wide association studies have opened the door for patient profiling and research into genetic variants in multifactorial T2DM. Clinically, it may be possible to tailor the type of medication used based on the presence or absence of the various genetic variants. However, the polymorphisms studied may only explain some of the variability in response to T2DM drugs and needs further validation to ensure its authenticity. There are still unidentified factors which appear to play a role in the interindividual variability seen in clinical practice. The potential exists for pharmacogenomics to promote efficacious, safe, and cost-effective individualized diabetes management. Pharmacogenomics is still in its early stages, and the idea of defining patients genetically to predict individual responses to drugs and obtain safe and effective T2DM management is promising, in spite of existing barriers. Currently, clinical profiling of patients with T2DM and using an individualized approach with most drugs, including canagliflozin, based on comorbid conditions still remains the most accepted approach for the management of T2DM.

Pharmacogenomics and pharmacogenetics of thiazolidinediones: role in diabetes and cardiovascular risk factors

The most important goal in the treatment of patients with diabetes is to prevent the risk of cardiovascular disease (CVD), the first cause of mortality in these subjects. Thiazolidinediones (TZDs), a class of antidiabetic drugs, act as insulin sensitizers increasing insulin-dependent glucose disposal and reducing hepatic glucose output. TZDs including pioglitazone, rosiglitazone and troglitazone, by activating PPAR-γ have shown pleiotropic effects in reducing vascular risk factors and atherosclerosis. However, troglitazone was removed from the market due to its hepatoxicity, and rosiglitazone and pioglitazone both have particular warnings due to being associated with heart diseases. Specific genetic variations in genes involved in the pathways regulated by TDZs have demonstrated to modify the variability in treatment with these drugs, especially in their side effects. Therefore, pharmacogenomics and pharmacogenetics are an important tool in further understand intersubject variability per se but also to assess the therapeutic potential of such variability in drug individualization and therapeutic optimization.

Adiponectin gene polymorphism rs2241766 T/G is associated with response to pioglitazone treatment in type 2 diabetic patients from southern China

INTRODUCTION

Insulin sensitizing drugs such as pioglitazone are not uniformly treatment effective among individual type 2 diabetic patients. Here, the relationship of pioglitazone efficacy to single nucleotide polymorphisms (SNP) of the adiponectin gene, a critical gene directly regulated by the drug, was examined in a cohort of Chinese Han type 2 diabetic patients.

METHODS

Eighty type 2 diabetic patients were treated with pioglitazone (15 mg/day) for 12 weeks without interruption of their current therapeutic regimen. Fasting plasma glucose, fasting insulin, homeostasis model assessment for insulin resistance (HOMA-IR), and glycated hemoglobin (HbA1c%) were collected both prior to and following pioglitazone treatment. Response to pioglitazone was defined as a decrease of at least 15% in HbA1c% levels. Three regions of the adiponectin gene containing SNPs (promoter, intron 2 and exon 2, and exon 3) were amplified and sequenced to determine genotype.

RESULTS

Serum adiponectin levels were significantly increased (p<0.001) whereas fasting plasma glucose, fasting insulin, HOMA-IR, and HbA1c% values were significantly decreased relative to baseline measurements (p<0.001). Response of patients with TG and TT genotypes at rs2241766 (exon2; 52.9% vs. 12.7%, respectively p = 0.001) was statistically significant relative to all other patients. Amongst rs2241766 TG and TT patients, the mean decrease in HbA1c% levels was greater where the genotype was TG (1.15±0.80 vs. 0.52±0.64, p = 0.001).

CONCLUSIONS

The adiponectin gene polymorphism rs2241766 T/G is associated with pioglitazone efficacy in type 2 diabetic patients, and status of the polymorphism may be an important clinical factor to consider prior to pioglitazone treatment.

The effect of IGF2BP2 gene polymorphisms on pioglitazone response in Chinese type 2 diabetes patients

BACKGROUND

Genome-wide association studies identified that insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) genetic polymorphisms are related to type 2 diabetes mellitus (T2DM) in several populations. This study aimed to investigate whether the IGF2BP2 gene rs1470579 and rs4402960 polymorphisms were associated with T2DM and pioglitazone efficacy in Chinese T2DM patients.

METHODS

A total of 281 T2DM patients and 111 healthy volunteers were enrolled to identify the IGF2BP2 gene rs1470579 and rs4402960 polymorphisms; 86 patients were randomly selected and given a 12-week pioglitazone treatment (30 mg/day). Fasting plasma glucose, postprandial plasma glucose (PPG), glycated hemoglobin, serum triglycerides (TG), total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol (HDL-C) were determined before and after pioglitazone treatment.

RESULTS

The results showed that the IGF2BP2 gene rs1470579 and rs4402960 polymorphisms were associated with T2DM in a Chinese population (OR = 2.002, 95% CI 1.170-3.426, p < 0.05; OR = 1.879, 95% CI 1.110-3.182, p < 0.05). The effect of pioglitazone on PPG (p < 0.05), TG (p < 0.01) and HDL-C (p < 0.05) was lower in patients with the rs1470579 AC+CC genotypes than in AA genotype carriers. Its effect on PPG level was also lower in patients with the GT+TT genotypes of rs4402960 than in patients with the GG genotype (p < 0.05).

CONCLUSIONS

The IGF2BP2 gene rs1470579 and rs4402960 polymorphisms were associated with T2DM and therapeutic efficacy of pioglitazone in this Chinese population.

Associations between C1431T and Pro12Ala variants of PPARγ gene and their haplotypes with susceptibility to metabolic syndrome in an Iranian population

Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear hormone receptor that regulates a number of genes involved in lipid and carbohydrate metabolism. The aim of this study was to investigate the association of C1431T and Pro12Ala polymorphisms of PPARγ gene and their haplotypes and diplotypes with risk of metabolic syndrome (MetS) in an Iranian population. A total of 340 unrelated Iranian subjects, including 175 MetS patients and 165 normal controls were enrolled. Each group was then divided into two subgroups according to the genotype (Pro/Pro and Pro/Ala+Ala/Ala for Pro12Ala, CC and CT+TT for C1431T). Genotypes were determined using a TaqMan method. Anthropometric indices, fasting plasma glucose and fasting lipid profile were measured by routine methods. A significant difference in the frequencies of the C1431T genotypes was observed between MetS and control subjects (P=0.014), whereas no association was found for the Pro12Ala. The T allele carriers had a significantly increased risk of MetS compared to the CC genotype (P=0.016) even after correction for multiple-testing and adjustment for age, sex and genotype. The T allele may therefore be considered as a risk factor for MetS (P=0.003). Analysis of combined groups showed that X/Ala-CC and Pro/Pro-X/T diplotypes were associated with a higher body weight, waist circumference and waist to hip ratio among the individuals with MetS. Moreover the Ala-T haplotype was weakly associated with a higher level of triglyceride and lower level of HDL, suggesting the possibility of an interaction between Ala and T alleles. This study suggests that the PPARγ C1431T polymorphism is related to an increased risk of MetS in an Iranian population and interacts with the Pro12Ala polymorphism, further increasing the risk of MetS.

Current clinical evidence on pioglitazone pharmacogenomics

Pioglitazone is the most widely used thiazolidinedione and acts as an insulin-sensitizer through activation of the Peroxisome Proliferator-Activated Receptor-γ (PPARγ). Pioglitazone is approved for use in the management of type 2 diabetes mellitus (T2DM), but its use in other therapeutic areas is increasing due to pleiotropic effects. In this hypothesis article, the current clinical evidence on pioglitazone pharmacogenomics is summarized and related to variability in pioglitazone response. How genetic variation in the human genome affects the pharmacokinetics and pharmacodynamics of pioglitazone was examined. For pharmacodynamic effects, hypoglycemic and anti-atherosclerotic effects, risks of fracture or edema, and the increase in body mass index in response to pioglitazone based on genotype were examined. The genes CYP2C8 and PPARG are the most extensively studied to date and selected polymorphisms contribute to respective variability in pioglitazone pharmacokinetics and pharmacodynamics. We hypothesized that genetic variation in pioglitazone pathway genes contributes meaningfully to the clinically observed variability in drug response. To test the hypothesis that genetic variation in PPARG associates with variability in pioglitazone response, we conducted a meta-analysis to synthesize the currently available data on the PPARG p.Pro12Ala polymorphism. The results showed that PPARG 12Ala carriers had a more favorable change in fasting blood glucose from baseline as compared to patients with the wild-type Pro12Pro genotype (p = 0.018). Unfortunately, findings for many other genes lack replication in independent cohorts to confirm association; further studies are needed. Also, the biological functionality of these polymorphisms is unknown. Based on current evidence, we propose that pharmacogenomics may provide an important tool to individualize pioglitazone therapy and better optimize therapy in patients with T2DM or other conditions for which pioglitazone is being used.

Pharmacogenetics of oral antidiabetic drugs

Oral antidiabetic drugs (OADs) are used for more than a half-century in the treatment of type 2 diabetes. Only in the last five years, intensive research has been conducted in the pharmacogenetics of these drugs based mainly on the retrospective register studies, but only a handful of associations detected in these studies were replicated. The gene variants in CYP2C9, ABCC8/KCNJ11, and TCF7L2 were associated with the effect of sulfonylureas. CYP2C9 encodes sulfonylurea metabolizing cytochrome P450 isoenzyme 2C9, ABCC8 and KCNJ11 genes encode proteins constituting ATP-sensitive K(+) channel which is a therapeutic target for sulfonylureas, and TCF7L2 is a gene with the strongest association with type 2 diabetes. SLC22A1, SLC47A1, and ATM gene variants were repeatedly associated with the response to metformin. SLC22A1 and SLC47A1 encode metformin transporters OCT1 and MATE1, respectively. The function of a gene variant near ATM gene identified by a genome-wide association study is not elucidated so far. The first variant associated with the response to gliptins is a polymorphism in the proximity of CTRB1/2 gene which encodes chymotrypsinogen. Establishment of diabetes pharmacogenetics consortia and reduction in costs of genomics might lead to some significant clinical breakthroughs in this field in a near future.

PPAR-γ2 and PTPRD gene polymorphisms influence type 2 diabetes patients' response to pioglitazone in China

AIM

To investigate the influence of peroxisome proliferator-activated receptor γ2 (PPAR-γ2) gene polymorphism rs1801282 and protein tyrosine phosphatase receptor type D (PTPRD) gene polymorphism rs17584499 on the occurrence of type 2 diabetes and pioglitazone efficacy in a Chinese Han population.

METHODS

One hundred ninety seven type 2 diabetes patients and 212 healthy controls were enrolled. Among them, 67 type 2 diabetes patients were administered pioglitazone (30 mg/d, po) for 3 months. All the subjects were genotyped for genetic variants in PPAR-γ2 and PTPRD using MALDI-TOF mass spectrometry. Fasting plasma glucose, postprandial plasma glucose, glycated hemoglobin, serum triglyceride, total cholesterol, low-density and high-density lipoprotein-cholesterol were determined.

RESULTS

The PPAR-γ2 gene rs1801282 polymorphism was significantly associated with type 2 diabetes susceptibility (OR=0.515, 95% CI 0.268-0.990) and the PTPRD gene rs17584499 polymorphism was also significantly associated with type 2 diabetes (OR=1.984, 95% CI 1.135-3.469) in a dominant model adjusted for age, gender and BMI. After pioglitazone treatment for 3 months, the type 2 diabetes patients with PPAR-γ2 rs1801282 CG genotypes significantly showed higher differential values of postprandial plasma glucose and serum triglyceride compared with those with rs1801282 CC genotype. The patients with PTPRD rs17584499 CT+TT genotypes showed significantly lower differential value of postprandial plasma glucose compared to those with rs17584499 CC genotype.

CONCLUSION

Diabetes risk alleles in PPAR-γ2 (rs1801282) and PTPRD (rs17584499) are associated with pioglitazone therapeutic efficacy.

The Pro12Ala polymorphism in the peroxisome proliferator-activated receptor gamma-2 gene (PPARγ2) is associated with increased risk of coronary artery disease: a meta-analysis

Background

Contradictory results have been reported regarding the association between Pro12Ala polymorphism of PPARγ2 and coronary artery disease (CAD). We sought to estimate the inconsistent results by performing a comprehensive meta-analysis.

Methods

Studies in English or Chinese publications were identified by screening MEDLINE, Embase, CNKI, Wanfang and CBM. 22 studies including 8948 cases and 14427 controls were selected. A random-effects model was applied to combine the divergent outcomes of the individual studies, while addressing between-study heterogeneity and publication bias.

Results

The Pro12Ala polymorphism of control population followed Hardy-Weinberg equilibrium for all studies (P>0.05). Overall, a marginal increased risk of CAD under the recessive genetic model (AlaAla vs ProAla+ProPro: P = 0.04, OR = 1.31, 95%CI 1.01–1.69, P_{heterogeneity} = 0.67, I² = 0%) and the homozygote comparison (AlaAla vs ProPro: P = 0.04,OR = 1.30, 95%CI 1.01–1.68, P_{heterogeneity} = 0.68, I² = 0%) was observed. In the subgroup analysis by ethnicity, carriers of AlaAla homozygotes had a significant increased risk for CAD among Caucasians (AlaAla vs ProAla+ProPro: P = 0.01, OR = 1.45, 95%CI 1.08–1.96, P_{heterogeneity} = 0.48, I² = 0%; AlaAla vs ProPro: P = 0.02,OR = 1.44, 95%CI 1.07–1.93, P_{heterogeneity} = 0.46, I² = 0%). After dividing into population source, the CAD risk magnitude of hospital-based studies was distinctly strengthened under the recessive model (P = 0.03,OR = 1.85,95%CI 1.07–3.19, P_{heterogeneity} = 0.87,I² = 0%) and the homozygote comparison (P = 0.03,OR = 1.83, 95%CI 1.06–3.16, P_{heterogeneity} = 0.88, I² = 0%). There was no observable publication bias as reflected by funnel plot and Egger’s linear regression test (t = -0.12, P = 0.91).

Conclusion:

Our results demonstrated that the PPARγ2 Pro12Ala polymorphism might be risk-conferring locus for the progression of CAD among Caucasians, but not among Asians.