Ajda Coker

Interleukin-1 receptor antagonist gene VNTR polymorphism is associated with coronary artery disease.

BACKGROUND Coronary Artery Disease (CAD) is the atherosclerosis of coronary arteries that carry blood to the heart muscle. Atherosclerosis is an inflammatory disease. Cytokine gene variations such as those associated with the IL1 family are involved in the pathogenesis of atherosclerosis. OBJECTIVE The purpose of this study was to determine the relationship between IL1 family polymorphisms (IL1RN VNTR, IL1B positions -511 and +3953) and CAD in Turkish population. METHODS 427 individuals were submitted to coronary angiography and were grouped as 170 control subjects and 257 CAD patients. The CAD subjects were divided into two subgroups: 91 Single Vessel Disease (SVD) and 166 Multiple Vessel Disease (MVD) subjects. The genotypes of IL1RN and of IL1B (-511, +3953) were determined by polymerase chain reaction (PCR) followed by restriction digestion analysis. RESULTS No significant difference was found in IL1RN and IL1B (-511 and +3953) genotype distributions between CAD and control subjects or MVD and control subjects. However, significant association was seen in IL1RN 2/2 genotype between SVD and control subjects (P= 0.016, x2: 10.289, OR: 2.94, 95% CI: 1.183-7.229). Similarly, no statistically significant difference was found in IL1RN and IL1B (-511 and +3953) allele frequencies between CAD and control subjects, MVD and control subjects or SVD and control subjects. CONCLUSION No association was found in either allele frequency or genotype distribution of IL1RN and IL1B polymorphisms between CAD and the control groups. However; IL1RN 2/2 genotype may be a risk factor for SVD in the Turkish population.

Polyamine depletion enhances the roscovitine-induced apoptosis through the activation of mitochondria in HCT116 colon carcinoma cells

Small molecule inhibitors of cyclin-dependent kinases (CDKs) show high therapeutic potential in various cancer types which are characterized by the accumulation of transformed cells due to impaired apoptotic machinery. Roscovitine, a CDK inhibitor showed to be a potent apoptotic inducer in several cancer cells. Polyamines, putrescine, spermidine and spermine, are biogenic amines involved in many cellular processes, including apoptosis. In this study, we explored the potential role of polyamines in roscovitine-induced apoptosis in HCT116 colon cancer cells. Roscovitine induced apoptosis by activating mitochondrial pathway caspases and modulating the expression of Bcl-2 family members. Depletion of polyamines by treatment with difluoromethylornithine (DFMO) increased roscovitine-induced apoptosis. Transient silencing of ornithine decarboxylase, polyamine biosynthesis enzyme and special target of DFMO also increased roscovitine-induced apoptosis in HCT116 cells. Interestingly, additional putrescine treatment was found pro-apoptotic due to the presence of non-functional ornithine decarboxylase (ODC). Finally, roscovitine altered polyamine catabolic pathway and led to decrease in putrescine and spermidine levels. Therefore, the metabolic regulation of polyamines may dictate the power of roscovitine induced apoptotic responses in HCT116 colon cancer cells.

Lack of association between IL‐1 and IL‐6 gene polymorphisms and myocardial infarction in Turkish population

Inflammation and genetics play a key role in the pathogenesis of atherosclerosis and its clinical result myocardial infarction (MI). Proinflammatory cytokines, IL‐1 and IL‐6, have been shown to play essential roles in developmental stages of coronary artery plaque formation. The aim of this study was to determine the association between IL‐1 [IL‐1RN, IL‐1β (−511, +3953)], IL‐6 [−174, −572, −597] gene polymorphisms and MI in Turkish population. A total of 402 people were participated; 235 healthy control subjects and 167 MI patients (MI < 40, n: 72; MI > 40, n: 95). Polymerase chain reaction (PCR) was used to determine the genotype of IL‐1RN, whereas the genotypes of IL‐1β (−511, +3953) and IL‐6 (−174, −572, −597) were determined using PCR followed with restriction digestion analysis. There was no significant difference between MI and controls for IL‐1RN, IL‐1β−511, +3953 (P: 0.875, 0.608, 0.442) and IL‐6 −174, −572, −597 (P: 0.977, 0.632, 0.584) gene polymorphisms. Lack of association was observed between MI at younger age (MI < 40) and either IL‐1RN VNTR, IL‐1β−511, +3953 (P: 0.878, 0.732, 0.978) or IL‐6 −174, −572, −597 (P: 0.313, 0.654, 0.552) gene polymorphisms. This study demonstrated that there was not any association between IL‐1, IL‐6 gene variants and MI in Turkish population. In addition, IL‐1 and IL‐6 gene polymorphisms did not affect MI at younger age (MI < 40) or older age (MI > 40). Thus, IL‐1 and IL‐6 single nucleotide polymorphisms may not be a risk factor for susceptibility to MI in Turkish population.

Association between sporadic Parkinson disease and interleukin-1β -511 gene polymorphisms in the Turkish population

The pathogenesis of Parkinson Disease (PD) remains poorly understood; however, inflammation is thought to play an important role in disease progression. Recent reports suggest that IL-1, a major proinflammatory cytokine, might play a role in PD progression. The purpose of this study was to determine the relationship between IL-1 gene family polymorphisms [IL-1 alpha (-889), IL-1Ra (VNTR) and IL-1 beta (-511, +3953)] and PD in the Turkish population. In this study, we examined the genotypes of IL-1 gene family polymorphisms in 365 individuals, of which 199 were healthy control subjects and 166 were PD patients. No significant differences were found in the genotype distribution or in the allele frequencies of IL-1 alpha (-889), IL-1Ra (VNTR) and IL-1 beta (+3953) between PD cases and control subjects. However, distribution of the IL-1 beta -511 2/2 (T/T) genotype was found to be significantly lower in PD patients than in healthy controls (p = 0.018, x2: 8.242, OR: 2.211, 95% CI: 1.261-3.877). In addition, the IL-1 beta -511 allele 1 (C) frequency was significantly elevated in PD patients versus controls (p = 0.048, x2: 3.87, OR: 1.178, 95% CI: 0.999-1.388). These results suggest that IL-1 alpha (-889), IL-1Ra and IL-1 beta (+3953) gene polymorphisms have no association with PD, while allele 1 (C) of IL-1 beta (-511) is associated with PD and may provide a susceptibility factor for this disease in the Turkish population. Furthermore, the 2/2 (T/T) genotype of IL-1 beta (-511) may protect individuals from PD.

Novel Splice Site Mutation in the Growth Hormone Receptor Gene in Turkish Patients with Laron-type Dwarfism

Growth hormone (GH) is involved in growth, and fat and carbohydrate metabolism. Interaction of GH with the GH receptor (GHR) is necessary for systemic and local production of insulin-like growth factor-I (IGF-I) which mediates GH actions. Mutations in the GHR cause severe postnatal growth failure; the disorder is an autosomal recessive genetic disease resulting in GH insensitivity, called Laron syndrome. It is characterized by dwarfism with elevated serum GH and low levels of IGF-I. We analyzed the GHR gene for mutations and polymorphisms in eight patients with Laron-type dwarfism from six families. We found three missense mutations (S40L, V125A, I526L), one nonsense mutation (W157X), and one splice site mutation in the extracellular domain of GHR. Furthermore, G168G and exon 3 deletion polymorphisms were detected in patients with Laron syndrome. The splice site mutation, which is a novel mutation, was located at the donor splice site of exon 2/ intron 2 within GHR. Although this mutation changed the highly conserved donor splice site consensus sequence GT to GGT by insertion of a G residue, the intron splicing between exon 2 and exon 3 was detected in the patient. These results imply that the splicing occurs arthe GT site in intron 2, leaving the extra inserted G residue at the end of exon 2, thus changing the open reading frame of GHR resulting in a premature termination codon in exon 3.

Silencing of the polyamine catabolic key enzyme SSAT prevents CDK inhibitor-induced apoptosis in Caco-2 colon cancer cells.

Roscovitine and purvalanol are purine derivative cyclin-dependent kinase (CDK) inhibitors that induce apoptosis in various types of cancer cells. However, their impact on the apoptotic cell death mechanism requires further elucidation. Natural polyamines putrescine, spermidine and spermine play essential roles in the regulation of cell growth and proliferation. Increased levels of polyamines in cells are considered to be involved in cancer progression. Intracellular polyamine levels are under the control of several catabolic enzymes, such as spermidine/spermine-N-acetyl transferase (SSAT), acetylpolyamine oxidase (APAO) and spermine oxidase (SMO), which could be altered by several therapeutic drugs. However, the possible role of polyamines in drug-induced apoptosis has yet to be clarified. In the present study, our aim was to determine the modulation of the polyamine catabolic pathway related to CDK inhibitor-induced apoptosis in Caco-2 cells. We found that roscovitine and purvalanol (each 20 μM) induced apoptosis by activating caspase-9 and -3, and inhibiting the mitochondrial membrane potential in Caco-2 cells. CDK inhibitors decreased the intracellular putrescine and spermine levels without affecting spermidine levels. Although both roscovitine and purvalanol induced SSAT expression, they did not exert a significant effect on the APAO expression profile. SSAT transient silencing prevented roscovitine-induced apoptosis compared to parental cells. Thus, we concluded that roscovitine and purvalanol significantly induce apoptosis in Caco-2 cells by modulating the polyamine catabolism, and that SSAT could be an important target in evaluating the potential role of polyamines in apoptotic cell death.

Interleukin-1B (-511) gene polymorphism is associated with acute coronary syndrome in the Turkish population

OBJECTIVES acute coronary syndrome (ACS) is defined as an inflammatory disease associated with development of atherosclerosis and instability. IL-1 is a candidate inflammatory cytokine that is thought to trigger ACS. The purpose of this study was to determine the relationship between IL-1 gene family polymorphisms (IL-1RN, IL-1B in positions -511 and +3953) and ACS in the Turkish population. METHODS a total of 381 people participated in the study, with 117 control subjects and 264 ACS patients. Of the 264 ACS patients, 112 were diagnosed with stable angina pectoris (SAP) and 152 were diagnosed with unstable angina pectoris (USAP). The polymerase chain reaction (PCR) was used to determine the genotype of IL-1RN. The genotypes of IL-1B (-511 and +3953) were determined by PCR, followed by restriction enzyme digestion of the PCR products. RESULTS there were no significant differences in both IL-1RN, IL-1B (-511 and +3953) genotype distributions and IL-1RN allele frequencies between ACS patients and the control subjects. In addition, no association was observed in the allele frequency of IL-1B (-511 and +3953) between ACS patients and controls (p = 0.113 and p = 0.859, respectively), or between SAP patients and controls (p = 0.575 and p = 0.359, respectively). However, IL-1B allele 1 (C) (-511) polymorphism in USAP patients was found to be significantly different from that of control subjects (p = 0.041, OR: 2.01; 95% CI: 1.985-3.933). A significant difference was also observed between USAP and SAP patients for IL-1B (+3953) allele 1 (C) polymorphism; (p = 0.043, OR: 1.522; 95% CI: 1.012-2.88). CONCLUSION these results show that IL-1RN gene polymorphism has no association with ACS. However, the allele 1 (C) of IL-1B (-511) may be a risk factor for susceptibility to USAP in the Turkish population.

Novel growth hormone receptor gene mutation in a patient with Laron syndrome.

ABSTRACT Growth Hormone (GH) is a 22 kDa protein that has effects on growth and glucose and fat metabolisms. These effects are initiated by binding of growth hormone (GH) to growth hormone receptors (GHR) expressed in target cells. Mutations or deletions in the growth hormone receptor cause an autosomal disorder called Laron-type dwarfism (LS) characterized by high circulating levels of serum GH and low levels of insulin like growth factor-1 (IGF-1). We analyzed the GHR gene for genetic defect in seven patients identified as Laron type dwarfism. We identified two missense mutations (S40L and W104R), and four polymorphisms (S473S, L526I, G168G and exon 3 deletion). We are reporting a mutation (W104R) at exon 5 of GHR gene that is not previously reported, and it is a novel mutation.

Characterization of GH-1 mutations in children with isolated growth hormone deficiency in the Turkish population.

Isolated growth hormone deficiency (IGHD) is defined as a medical condition associated with growth failure due to insufficient production of growth hormone (GH) or lack of growth hormone action. It occurs with an incidence of between 1/4,000 and 1/10,000 live births. Most cases are sporadic and idiopathic but 5-30% of growth hormone deficiency (GHD) has genetic etiology. Mutations in the GH encoding gene (GH-1) have been detected in patients with IGHD. The purpose of this study was to characterize mutations of the GH-1 gene in children with IGHD in the Turkish population. We found four missense mutations (E33G, N47D, T-24A and A13S), one nonsense mutation (W-7X), one insertion and two deletions in nine patients out of seventy-five patients with IGHD. The missense mutation A13S, GAAA insertion at intron 1 (+178A), and the deletions of +83C in intron 1 and deltaF166 in exon 5 are novel mutations.