Publications (25) View all
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Article: Vascular endothelial growth factor family gene polymorphisms in preeclampsia in Sinhalese women in Sri-Lanka.
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ABSTRACT: Abstract Objective: To investigate the association of polymorphisms in the VEGF family genes (VEGFA rs699947, VEGFA rs3025039, PGF rs1042886, KDR rs2071559 and KDR rs2305948) with preeclampsia in Sinhalese women in Sri-Lanka. Method: We conducted a case-control study where 175 nulliparous Sinhalese women with preeclampsia and 171 normotensive women matched for age, ethnicity, parity and BMI were recruited in tertiary care maternity hospitals in Sri-Lanka. Preeclampsia was diagnosed using international guidelines. DNA extracted from peripheral venous blood and was genotyped using the Sequenom MassARRAY system. Chi square test was used to compare the distribution of allele and genotype frequencies between the cases and the control subjects. Results: The frequency of PGF rs1042886 variant allele (OR 1.5, 95% CI 1.1-2.1) and dominant genotype model (aOR 1.6, 95% CI 1.0-2.4) were increased in preeclamptic women compared to controls. VEGFA rs699947, VEGFA rs3025039, KDR rs2071559 and KDR rs2305948 polymorphisms were not associated with preeclampsia. Conclusion: Maternal PGF rs1042886 polymorphism is associated with preeclampsia in Sinhalese women in Sri-Lanka.The journal of maternal-fetal & neonatal medicine: the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians 10/2012; · 1.36 Impact Factor -
Article: Characterization of the prostate cancer susceptibility gene KLF6 in human and mouse prostate cancers.
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ABSTRACT: BACKGROUND: Krüppel-like factor (KLF) 6 is a candidate tumor suppressor gene in prostate cancer, but the mechanisms contributing to its loss of expression are poorly understood. We characterized KLF6 expression and DNA methylation status during prostate tumorigenesis in humans and mice. METHODS: KLF6 expression was assessed in matched human non-malignant (NM) and tumor prostate tissues (n = 22) by quantitative real-time PCR (qPCR) and in three independent human prostate cancer cohorts bioinformatically. QPCR for KLF6 expression and methylation-sensitive PCR (MSP) were performed in human prostate LNCaP cancer cells after 5-aza-2'-deoxycytidine treatment. Klf6 protein levels and DNA promoter methylation were assessed in TRansgenic Adenocarcinoma of Mouse Prostate (TRAMP) tumors by immunohistochemistry and MSP, respectively. RESULTS: KLF6 splice variants expression was increased (P = 0.0015) in human prostate tumors compared to NM tissues. Overall, KLF6 was decreased in metastatic compared to primary prostate cancers and reduced expression in primary tumors was associated with a shorter time to relapse (P = 0.0028). Treatment with the demethylating agent 5-aza-2'-deoxycytidine resulted in up-regulation of KLF6 expression (two-fold; P = 0.002) and a decrease in DNA methylation of the KLF6 promoter in LNCaP cells. Klf6 protein levels significantly decreased with progression in the TRAMP model of prostate cancer (P < 0.05), but there was no difference in Klf6 promoter methylation. CONCLUSION: KLF6 expression was decreased in both clinical prostate cancer and the TRAMP model with disease progression, but this could not be explained by DNA methylation of the KLF6 promoter. Prostate © 2012 Wiley Periodicals, Inc.The Prostate 07/2012; · 3.48 Impact Factor -
Article: An androgen receptor mutation in the MDA-MB-453 cell line model of molecular apocrine breast cancer compromises receptor activity.
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ABSTRACT: Recent evidence indicates that the estrogen receptor-α-negative, androgen receptor (AR)-positive molecular apocrine subtype of breast cancer is driven by AR signaling. The MDA-MB-453 cell line is the prototypical model of this breast cancer subtype; its proliferation is stimulated by androgens such as 5α-dihydrotestosterone (DHT) but inhibited by the progestin medroxyprogesterone acetate (MPA) via AR-mediated mechanisms. We report here that the AR gene in MDA-MB-453 cells contains a G-T transversion in exon 7, resulting in a receptor variant with a glutamine to histidine substitution at amino acid 865 (Q865H) in the ligand binding domain. Compared with wild-type AR, the Q865H variant exhibited reduced sensitivity to DHT and MPA in transactivation assays in MDA-MB-453 and PC-3 cells but did not respond to non-androgenic ligands or receptor antagonists. Ligand binding, molecular modeling, mammalian two-hybrid and immunoblot assays revealed effects of the Q865H mutation on ligand dissociation, AR intramolecular interactions, and receptor stability. Microarray expression profiling demonstrated that DHT and MPA regulate distinct transcriptional programs in MDA-MB-453 cells. Gene Set Enrichment Analysis revealed that DHT- but not MPA-regulated genes were associated with estrogen-responsive transcriptomes from MCF-7 cells and the Wnt signaling pathway. These findings suggest that the divergent proliferative responses of MDA-MB-453 cells to DHT and MPA result from the different genetic programs elicited by these two ligands through the AR-Q865H variant. This work highlights the necessity to characterize additional models of molecular apocrine breast cancer to determine the precise role of AR signaling in this breast cancer subtype.Endocrine Related Cancer 06/2012; 19(4):599-613. · 4.36 Impact Factor -
Article: Epigenetic biomarkers in prostate cancer: Current and future uses.
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ABSTRACT: Epigenome alterations are characteristic of nearly all human malignancies and include changes in DNA methylation, histone modifications and microRNAs (miRNAs). However, what induces these epigenetic alterations in cancer is largely unknown and their mechanistic role in prostate tumorigenesis is just beginning to be evaluated. Identification of the epigenetic modifications involved in the development and progression of prostate cancer will not only identify novel therapeutic targets but also prognostic and diagnostic markers. This review will focus on the use of epigenetic modifications as biomarkers for prostate cancer.Cancer letters 03/2012; · 4.86 Impact Factor -
Article: Quantitative Allele-Specific Expression and DNA Methylation Analysis of H19, IGF2 and IGF2R in the Human Placenta across Gestation Reveals H19 Imprinting Plasticity.
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ABSTRACT: Imprinted genes play important roles in placental differentiation, growth and function, with profound effects on fetal development. In humans, H19 and IGF2 are imprinted, but imprinting of IGF2R remains controversial. The H19 non-coding RNA is a negative regulator of placental growth and altered placental imprinting of H19-IGF2 has been associated with pregnancy complications such as preeclampsia, which have been attributed to abnormal first trimester placentation. This suggests that changes in imprinting during the first trimester may precede aberrant placental morphogenesis. To better understand imprinting in the human placenta during early gestation, we quantified allele-specific expression for H19, IGF2 and IGF2R in first trimester (6-12 weeks gestation) and term placentae (37-42 weeks gestation) using pyrosequencing. Expression of IGF2R was biallelic, with a mean expression ratio of 49∶51 (SD = 0.07), making transient imprinting unlikely. Expression from the repressed H19 alleles ranged from 1-25% and was higher (P<0.001) in first trimester (13.5±8.2%) compared to term (3.4±2.1%) placentae. Surprisingly, despite the known co-regulation of H19 and IGF2, little variation in expression of the repressed IGF2 alleles was observed (2.7±2.0%). To identify regulatory regions that may be responsible for variation in H19 allelic expression, we quantified DNA methylation in the H19-IGF2 imprinting control region and H19 transcription start site (TSS). Unexpectedly, we found positive correlations (P<0.01) between DNA methylation levels and expression of the repressed H19 allele at 5 CpG's 2000 bp upstream of the H19 TSS. Additionally, DNA methylation was significantly higher (P<0.05) in first trimester compared with term placentae at 5 CpG's 39-523 bp upstream of the TSS, but was not correlated with H19 repressed allele expression. Our data suggest that variation in H19 imprinting may contribute to early programming of placental phenotype and illustrate the need for quantitative and robust methodologies to further elucidate the role of imprinted genes in normal and pathological placental development.PLoS ONE 01/2012; 7(12):e51210. · 4.09 Impact Factor
