Saime Turan

Cyclin D1 Gene G870A Variants and Primary Brain Tumors

Alterations of cyclin D1, one of the main regulators of the cell cycle, are known to be involved in various cancers. The CCDN1 G870A polymorphism causes production of a truncated variant with a shorter half-life and thus thought to impact the regulatory effect of CCDN1. The aim of the present study was to contribute to existing results to help to determine the prognostic value of this specific gene variant and evaluate the role of CCDN1 G870A polymorphism in brain cancer susceptibility. A Turkish study group including 99 patients with primary brain tumors and 155 healthy controls were examined. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism analysis. The CCDN1 genotype frequencies in meningioma, glioma and control cases were not significantly different (p>0.05). No significant association was detected according to clinical parameters or tumor characteristics; however, a higher frequency of AG genotype was recorded within patients with astrocytic or oligoastrocytic tumors. A significant association between AG genotype and gliobilastoma multiforme (GBM) was recorded within the patients with glial tumors (p value=0.048 OR: 1.87 CI% 1.010-3.463). According to tumor characteristics, no statistically significant difference was detected within astrocytic, oligoasltrocytic tumors and oligodentrioglias. However, patients with astrocytic astrocytic or oligoastrocytic tumors showed a higher frequency of AG genotype (50%) when compared to those with oligodendrioglial tumors (27.3%). Our results indicate a possible relation between GBM formation and CCDN1 genotype.

Possible Relation between the NOS3 Gene GLU298ASP Polymorphism and Bladder Cancer in Turkey

Endothelial nitric oxide synthase (eNOS), encoded by the NOS3 gene, has been suggested to play an important role in uncontrolled cell growth in several cancer types. The objective of this study was to evaluate the role of the NOS3 Glu298Asp polymorphism in bladder cancer susceptibility in a Turkish population. We determined the genotypes of 66 bladder cancer cases and 88 healthy controls. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism analysis. A significant association for NOS3 Glu298Asp heterozygotes genotypes and T allely were found between healthy controls and bladder cancer, respectively (p<0.001: p=0.002). There were no significant associations between any genotypes and the stage, grade, and histological type of bladder cancer. Our study suggested an increased risk role of NOS3 GT genotype in bladder cancer susceptibility in our Turkish population.

The Vitamin D Receptor (VDR) Gene Polymorphisms in Turkish Brain Cancer Patients

Objective. It has been stated that brain cancers are an increasingly serious issue in many parts of the world. The aim of our study was to determine a possible relationship between Vitamin D receptor (VDR) gene polymorphisms and the risk of glioma and meningioma. Methods. We investigated the VDR Taq-I and VDR Fok-I gene polymorphisms in 100 brain cancer patients (including 44 meningioma cases and 56 glioma cases) and 122 age-matched healthy control subjects. This study was performed by polymerase chain reaction-based restriction fragment length polymorphism (RF LP). Results. VDR Fok-I ff genotype was significantly increased in meningioma patients (15.9%) compared with controls (2.5%), and carriers of Fok-I ff genotype had a 6.47-fold increased risk for meningioma cases. There was no significant difference between patients and controls for VDR Taq-I genotypes and alleles. Conclusions. We suggest that VDR Fok-I genotypes might affect the development of meningioma.

Do CDKN2 p16 540 C>G, CDKN2 p16 580 C>T, and MDM2 SNP309 T>G Gene Variants Act on Colorectal Cancer Development or Progression?

CDNK2 p16 plays a pivotal role in G1/S transition by regulating the p53 pathway, which was regulated by a nuclear oncoprotein, mouse double minute 2 (MDM2). Overexpression of the MDM2 gene has been shown in a number of tumor types, its gene amplification is found to associate with accelerated tumor development and failure to treatment in both hereditary and sporadic cancers. Although genetic association studies have revealed the relationship between certain genetic polymorphisms and genes that play important roles in the development and progression of colorectal cancer (CRC), it is still unknown. Therefore, the polymorphisms of p16 540 C>G, 580 C>T, and MDM2 SNP309 T>G designed to investigate the risk of CRC development and progression in a Turkish population. We enrolled 87 patients with CRC and 75 healthy controls into the study. Genotypings were determined using polymerase chain reaction-restriction fragment length polymorphism techniques. Genotype distributions of p16 540 C>G and 580 C>T were found in agreement with the Hardy-Weinberg equilibrium in patients and controls. MDM2 SNP309 T>G was found in agreement with the Hardy-Weinberg equilibrium in controls, but not in patients. The results of our study, the G allele of p16 540 C>G and GG genotype of MDM2 SNP309 T>G were found significantly lower in patients compared with controls (p<0.001, p<0.05, respectively). Haplotype analyses have shown that the C allele of both the CDKN2 p16 540 C>G and 580 C>T variants together indicate a risk haplotype for the patient group; besides, carrying the G allele of p16 540 and G allele of MDM2 also seems a risk haplotype for the patient group. Our study is the first study that investigates the relationship among variants of CDKN2 p16 540 C>G, 580 C>T, and MDM2 SNP309 T>G risk of CRC and the development and progression in the Turkish population.

Association between Laryngeal Squamous Cell Carcinoma and Polymorphisms in Tumor Necrosis Factor Related Apoptosis Induce Ligand (TRAIL), TRAIL Receptor and sTRAIL Levels

The laryngeal squamous cell carcinoma (LSCC) is one of the most common malignant tumors occurring in the head and neck. Tumor necrosis factor related apoptosis induce ligand (TRAIL) and TRAIL-receptors (DR4, DR5, DcR1, DcR2) are known as important members of TRAIL-mediated biochemical signaling pathway. Associations between polymorphisms in these genes and clinicopathological characteristics of human laryngeal carcinoma are not well defined. This study therefore aimed to investigate a possible relationship among the TRAIL and TRAIL-DR4 polymorphisms and sTRAIL levels in the risk or progression of LSCC. A total of 99 patients with laryngeal cancer and 120 healthy subjects were enrolled in the study. DR4 C626G and TRAIL 1595 C/T genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis and sTRAIL levels were measured by ELISA. There were significant differences in the distribution of DR4 C626G genotypes and frequencies of the alleles between laryngeal cancer patients and controls (p<0.001) but not in TRAIL 1595 C/T. We found the increased frequency of the DR4 C626G homozygote CC genotype in patients than in controls (p<0.001). Haplotype analysis revealed that there was also a statistically significant relationship between TRAIL and TRAIL-DR4 polymorphisms and laryngeal cancer. Serum sTRAIL levels in the laryngeal patients with CC genotype who had advanced tumour stage were lower than those of patients with early tumor stage (p=0.014). Our findings suggest that DR4 C626G genotypes and sTRAIL levels might be associated with progression of laryngeal cancer in the Turkish population.

Relation between Endothelial Nitric Oxide Synthase Genotypes and Oxidative Stress Markers in Larynx Cancer

Nitric oxide synthase (eNOS/NOS3) is responsible for the endothelial synthesis of nitric oxide (NO•). G894T polymorphism leads to the amino acid substitution from Glu298Asp that causes lower NOS3 activity and basal NO• production in NOS3 894T (298Asp) allele carriers compared with the GG homozygotes. NO• acts as an antioxidant protecting against Fentons reaction which generates highly reactive hydroxyl radicals. Allelic variation of NOS3 may influence an individuals risk of laryngeal cancer (LC). In the current study we have examined the possible relationship between NOS3 G894T genotypes and various systemic oxidative damage markers such as protein carbonyl, advanced oxidation protein products, Cu, Zn-superoxide dismutase, thiol group fractions, and lipid hydroperoxides in LC patients. Genotyping was carried out by PCR-RFLP. In LC patients with TT genotype, Cu, Zn-superoxide dismutase activities and nonprotein thiol levels were significantly higher than the controls. In patients with GT and GG genotype, high levels of lipid hydroperoxides showed statistical significance when compared to controls. Our results indicate a potential relationship among G894T polymorphism of NOS3, and impaired redox homeostasis. Further studies are required to determine the role of NOS3 gene polymorphism and impaired plasma redox homeostasis.

Association between FAS and FASL genetic variants and risk of primary brain tumor.

The purpose of this study was to investigate whether functional polymorphisms of apoptosis pathway genes FAS and FASL are associated with the development of primary brain tumors. The study constituted 83 patients with primary brain tumor and 108 healthy individuals. In the present case-control study, the primary brain tumors were divided into two groups: gliomas and meningiomas. Evaluation of FAS -1377 G/A and FASL -844 T/C gene polymorphisms were performed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). To confirm the genotyping, results were examined by DNA sequencing method. Our results were analyzed by SPSS. The frequency of the FAS -1377 AA genotype was significantly lower in meningioma and glioma patients compared to controls (p = 0.023; p = 0.001, respectively). Multivariate logistic regression analysis revealed that FAS -1377 AA genotype was associated with decreased risk of meningioma and glioma (OR = 0.092, 95% CI: 0.012–0.719, p = 0.023 for meningiomas; OR = 0.056, 95% CI: 0.007–0.428, p = 0.006 for gliomas). However, there was no significant differences in FASL -844 T/C genotype frequencies between patients with primary brain tumors and controls (p > 0.05). In this study, combined genotypes were evaluated for association with primary brain tumors. Combined genotype analysis showed that the frequencies of AATC and AACC were significantly lower in glioma patients in comparison with those of controls (p = 0.023; p = 0.022, respectively). This study provides the first evidence that FAS -1377 AA genotype may have a protective effect on the developing primary brain tumor in a Turkish population.

Investigation of the Vitamin D Receptor Polymorphisms in Acromegaly Patients

Objective. The genetic structural alterations in the majority of somatotroph adenomas are not clarified and the search for novel candidate genes is still a challenge. We aimed to investigate possible associations between vitamin D receptor (VDR) polymorphisms and acromegaly. Design, Patients, and Methods. 52 acromegaly patients (mean age 45.7 ± 1.9 years) and 83 controls (mean age 43.1 ± 2.6 years) were recruited to the study. VDR polymorphism was determined by polymerase chain reaction-based restriction fragment length polymorphism methods. Results. The distribution of VDR genotypes showed a significant difference in the frequencies of VDR FokI genotypes between patients and controls (P = 0.034). VDR FokI ff genotype was significantly decreased in acromegaly patients (P = 0.035) and carriers of FokI Ff genotype had a 1.5-fold increased risk for acromegaly (OR: 1.5, 95% CI: 1.07–2.1; P = 0.020). IGF1 levels after treatment were significantly higher in patients carrying the Ff genotype compared to carrying ff genotype (P = 0.0049). 25(OH)D3 levels were significantly lower in acromegaly patients (P < 0.001). Conclusions. Our study suggests that VDR FokI genotypes might affect the development of acromegaly and VDR polymorphisms may play a role in the course of acromegaly as a consequence of altering hormonal status.

Hepatocellular carcinoma: targeting of oncogenic signaling networks in TRAIL resistant cancer cells

Apoptotic response in hepatocellular carcinoma (HCC) cells is impaired because of interconnectivity of proteins into complexes and signaling networks that are highly divergent in time and space. TNF-related apoptosis-inducing ligand (TRAIL) has emerged as an attractive anticancer agent reported to selectively induce apoptosis in cancer cells. Although diametrically opposed roles of TRAIL are reported both as an inducer of apoptosis and regulator of metastasis, overwhelmingly accumulating experimental evidence highlighting apoptosis inducing activity of TRAIL is directing TRAIL into clinical trials. Insights from TRAIL mediated signaling in HCC research are catalyzing new lines of study that should not only explain molecular mechanisms of disease but also highlight emerging paradigms in restoration of TRAIL mediated apoptosis in resistant cancer cells. It is becoming progressively more understandable that phytochemicals derived from edible plants have shown potential in modelling their interactions with their target proteins. Rapidly accumulating in vitro and in-vivo evidence indicates that phytonutrients have anticancer activity in rodent models of hepatocellular carcinoma. In this review we bring to limelight how phytonutrients restore apoptosis in hepatocellular carcinoma cells by rebalancing pro-apoptotic and anti-apoptotic proteins. Evidence has started to emerge, that reveals how phytonutrients target pharmacologically intractable proteins to suppress cancer. Target-based small-molecule discovery has entered into the mainstream research in the pharmaceutical industry and a better comprehension of the genetics of patients will be essential for identification of responders and non-responders.

Does DRD2 polymorphism influence the clinical characteristics of prolactinoma

OBJECTIVES Genetic alterations explaining the clinical variability of prolactinomas still could not be clarified and dopamine D2 receptor (DRD2) polymorphism is a putative candidate for the variable response to dopaminergic treatment. The present study was conducted to investigate the influence of DRD2 TaqI A polymorphism on initial and follow-up characteristics of prolactinoma. PATIENTS AND METHODS Seventy-two patients with prolactinoma and 98 age and gender matched control subjects were recruited to the case-control study. Serum prolactin levels were assessed by enzyme-linked immunosorbent assay and DRD2 polymorphism was determined by polymerase chain reaction and restriction length polymorphism analysis. RESULTS Decrease of prolactin levels and the tumor shrinkage after cabergoline treatment were 93.9±5.9% and 58.3±33.1% in microadenomas and 96.1±6.1% and 51.7±29.3 in macroadenomas (P=0.02 and P>0.05, respectively). We observed no significant difference for DRD2 genotypes and the alleles between the patients and healthy group (P>0.05). Prolactin levels before treatment were correlated with tumor diameter before and after treatment and the percentage of prolactin decrease with treatment (P<0.001 r=0.58, P<0.001 r=0.40 and P<0.001 r=0.47, respectively). Tumor diameter before the treatment was also correlated with the tumor diameter after the treatment (P<0.001 r=0.64) and the percentage of prolactin decrease (P=0.01 r=0.30). However, no significant association was found between characteristics of prolactinoma and DRD2 genotypes and alleles (P>0.05). CONCLUSION This study revealed that DRD2 TaqI A receptor polymorphism was not associated with the development of prolactinoma and its clinical characteristics. Future studies are needed to clarify the clinical implications of genetic alterations in prolactinoma.