ÖZET
Amaç:
Bu çalışmanın amacı; kolorektal kanserli olguların parafin bloklarından elde edilen genomik DNA’da 6 farklı gen bölgesinin promoter metilasyonu ve mikrosatellite instabilitesini araştırmak ve bunların kolorektal kanser gelişimindeki önemini değerlendirmektir.
Yöntemler:
Yetmiş altı sporadik kolorektal kanserli olguya ait parafin dokusundan tümörlü olduğu belirlenen bölgelerden kesit alınarak DNA izolasyonu gerçekleştirilmiştir. Bu DNA örneklerinden metilasyon spesifik-PCZ (MS-PZR) yöntemi ile APC, hMLH1, p16INK4A, p15, p73 ve DAPK1 genlerine ait promoter bölgesi metilasyonu araştırılmıştır, aynı zamanda mikrosatellit instabilitesi (MSI) varlığı 3 farklı STR bölgesi incelenerek belirlenmiştir.
Bulgular:
Hasta örneklerimize ait genlerin metilasyon oranlarını hMLH1 için %24, APC için %31,5, DAPK1 için %19,6, p16 için %42,8, p15 için %30, p73 için %17 bulduk. Verilerin daha iyi anlaşılması için metilasyon indeksi (Mİ) hesaplandı. Bir örnek için metile olan gen sayısının analiz edilen gen sayısına oranı şeklinde hesapladığımız Mİ değeri 0-0,83 arasında bulundu. Ortalama Mİ 0,271 idi (1,6 gen/numuneye karşılık gelir) ve medyan değeri 0,225 idi. Herhangi bir lokusta metilasyona uğramayan 15 örnek vardı. MSİ’yi C-kit (21%), hMSH2 (18%) ve APC (15%) mikrosatellit bölgelerinde analiz ettik.
Sonuç:
Literatüre göre Türk populasyonunda APC metilasyonunun diğer popülasyondan daha sık olduğunu belirledik. P16 promoter metilasyonunun 6 gen arasında en fazla metilasyona uğrayan lokus olduğu ve kadın hastalarda daha sık metillendiği görülmüştür. P73 metilasyonu ise sıklıkla sol kolorektal kanserlerde belirlenmiş ve ek olarak da MSİ ile ilişkili bulunmuştur.
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