title: Epigenetic mechanisms regulate placental c-myc and hTERT in normal and pathological pregnancies; c-myc as a novel fetal DNA epigenetic marker for pre-eclampsia.
abstract: Placental development is known for its resemblance with tumor development, such as in the expression of oncogenes (c-myc) and telomerase (hTERT). The expression of c-myc and hTERT is up-regulated during early pregnancy and gestational trophoblastic diseases (GTDs). To determine the role of DNA methylation [via methylation-sensitive high resolution melting (MS-HRM)] and histone modifications [via chromatin immunoprecipitation (ChIP assay)] in regulating the differential expression of c-myc and hTERT during normal gestation and their dysregulation during placental disorders, we obtained placental samples from 135 pregnant women, in five groups: normal first, second and third trimester (n = 30 each), pre-eclamptic pregnancy (n = 30) and molar pregnancy (n = 15). Two placental cell lines (JEG-3 and HTR-8/SVneo) and isolated first-trimester cytotrophoblasts were also studied. Quantitative RT-PCR revealed decreased mRNA expression levels of c-myc and hTERT, which were associated with a higher level of H3K9me3 (1.5-fold, P < 0.05) and H3K27me3 (1.9-fold, P < 0.05), respectively, in third-trimester placental villi versus first-trimester villi. A significantly lower level of H3K27me3 in molar placenta was associated with a higher mRNA expression of c-myc and hTERT. The development of pre-eclampsia (PE) was associated with increased methylation (P < 0.001) and H3K27me3 (P < 0.01) at the c-myc promoter and reduced H3K9me3 (P < 0.01) and H3K27me3 (P < 0.05) at the hTERT promoter. Further, mRNA expression of c-myc and hTERT was strongly correlated in molar villi (r = 0.88, P < 0.01) and JEG-3 cells (r = 0.99, P < 0.02). Moreover, on the basis of methylation data, we demonstrate the potential of c-myc as a fetal DNA epigenetic marker for pre-eclamptic pregnancies. Thus we suggest a role for epigenetic mechanisms in regulating differential expression of c-myc and hTERT during placental development and use of the c-myc promoter region as a potential fetal DNA marker in the case of PE.
authors.affiliation: Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India.
authors.forename: Beenish
authors.initials: B
authors.lastname: Rahat
authors.affiliation: Cancer Pharmacology Division, Indian Institute of Integrative Medicine, Jammu 180001, India.
authors.forename: Abid
authors.initials: A
authors.lastname: Hamid
authors.affiliation: Cancer Pharmacology Division, Indian Institute of Integrative Medicine, Jammu 180001, India.
authors.forename: Rauf
authors.initials: R
authors.lastname: Ahmad Najar
authors.affiliation: Department of Obstetrics and Gynaecology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India.
authors.forename: Rashmi
authors.initials: R
authors.lastname: Bagga
authors.affiliation: Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India jyotdeep2001@yahoo.co.in.
authors.forename: Jyotdeep
authors.initials: J
authors.lastname: Kaur
mesh_terms: D000328:Adult; D002478:Cells, Cultured; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D044127:Epigenesis, Genetic; D005260:Female; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006828:Hydatidiform Mole / Q000235:genetics*; D010920:Placenta / Q000473:pathology; D010929:Placentation / Q000235:genetics; D011225:Pre-Eclampsia / Q000235:genetics*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis; D019098:Telomerase / Q000096:biosynthesis; D014327:Trophoblasts; D014594:Uterine Neoplasms / Q000235:genetics*
chemical_list: D006657:Histones; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D019098:Telomerase
keywords: DNA methylation; gestational trophoblastic diseases; histone modifications; placenta; pre-eclampsia