319 KB19 KB199220252000Cör, Andrejletnik:34številka:4str. 369-374COBISSID:12586969ISSN:1318-2099URN:URN:NBN:SI:doc-GNCU2E1AenCroatian Medical Association - Croatian Society of RadiologySlovenian Medical Society - Section of RadiologyRadiology and oncology (Ljubljana)biokemijaDNA methylationfiziologijakarcinommaligne celiceMethyltransferasesOvarian neoplasmsPolymerase chain reactionThe relationship between DNA methylation and expression of three different DNA methyltransferases in ovarian cancer|Background. DNA methylation in mammals is required for embryonic development, X chromosome inactivation and imprinting. Previous studies have shown that methylation patterns become abnormal in malignant cells and may contribute to tumorigenesis. The aim of the study was to ascertain the relationship between overall DNA methylation and the expression of DNMT1, DNMT3A and DNMT3B in ovarian cancer samples. Material and methods. DNA digestion with either methylation sensitive HpaII, or methylation insensitive MspI restriction endonuclease and quantitative reverse transcription-PCR methods were used to analyse global methylation levels and expression levels of five ovarian cancerand three normal ovarian tissue samples. Results. All five analysed cancer samples were hypomethylated. The differences of methylation levels between normal ovarian tissue and carcinoma samples were statistically significant (P<0.05). All five cancer samples showed overexpression of DNMT3A and DNMT3B, and only two ovarian tumour samples showed overexpression of DNMT1. There was no correlation between global demethylation and expression levels for the three different DNMTs.Conclusion. Genome wide hypomethylation facilitates tumor development with predisposition of cells to structural and numerical chromosomal aberrations but the paradox of the global hypomethylation observed in cancer cells and the high levels of DNMTs that arepresent in these cells still remain to be resolvedIzhodišča. Metilacija DNA igra pomembno vlogo v razvoju zarodka, pri inaktivaciji kromosoma X ter pri izražanju "imprinting" genov. Raziskave so pokazale, da imajo maligne celice spremenjen vzorec metilacije DNA, spremembe DNA metilacije pa sodelujejo v procesu kancerogeneze. Namen dela je bil ugotoviti ali obstaja povezava med stopnjo metilacije DNA ter izražanjem treh DNA metil-transferaz (DNMT) in sicer DNMT1, DNMT3A in DNMT3B v vzorcih ovarijskih karcinomov. Materiali in metode. Za določitev stopnje metilacije DNA v petih vzorcih ovarijskega karcinoma in treh vzorcih morfološko normalnihjajčnikov je bila DNA izpostavljena delovanju bodisi za metilacijo občutljive HpaII, ali za metilacijo neobčutljive MspI restrikcijske endonukleaze. Za določitev stopnje izražanja treh DNMT v vzorcih smo uporabilimetodo kvantitativnega PCR. Rezultati. DNA vseh petih ovarijskih karcinomov je bila globalno hipometilirana. Razlike med stopnjo metilacije DNAmed ovarijskimi karcinomi in normalnim tkivom jajčnika so bile statistično značilne (p<0.05). Vseh pet ovarijskih karcinomov je kazalo prekomerno izražanje DNMT3A in DNMT3B, medtem ko smo našli prekomerno izražanje DNMT1 samo v dveh vzorcih. Med stopnjo globalne demetilacije in izražanjem treh različnih DNMT ni bilo statistično značilnik korelacij. Zaključki. Hipometilacija genoma igra pomembno vlogo pri nastanku tumorjev saj vodi v strukturne in numerične kromosomske nepravilnosti v tumorskih celicah, vendar pa ostaja paradoks med stopnjo globalne hipometilacije na eni strani in povečanim izražanjem DNMT na drugi še vedno nerazjasnjenTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaOnkološki inštitut Ljubljana