ÖZ
Amaç
Luminal B tipi meme kanseri, artmış tümör agresifliği ve özgün moleküler özellikleriyle karakterize olup, trastuzumab ve tamoksifen gibi hedefe yönelik tedavilere karşı direnç gelişimiyle sıklıkla ilişkilidir. MikroRNA'lar (miRNA), kanser progresyonu ve tedavi yanıtının temel düzenleyicileri olarak öne çıkmaktadır. Bu çalışmada, miR-99b-5p’nin Luminal B meme kanserinde tedavi direncini düzenleyici rolü araştırılmıştır.
Yöntemler
Trastuzumab’a duyarlı ve trastuzumab dirençli BT-474 meme kanseri hücrelerinde, miR-99b-5p’nin fonksiyonu, özgül mimik ve inhibitörler kullanılarak değerlendirilmiştir. Gen ve protein ekspresyon düzeyleri sırasıyla qRT-PCR ve Western blot yöntemleriyle analiz edilmiştir. Ayrıca, ENCORI, UALCAN, GeneMiner, ROCplot ve UbiBrowser gibi biyoinformatik veri tabanları aracılığıyla hedef genlerin ekspresyon profilleri ve tedavi cevabı ile ilişkisi incelenmiştir.
Bulgular
miR-99b-5p ekspresyonu, tamoksifen veya trastuzumab uygulaması sonrasında ilaca duyarlı BT-474 hücrelerinde azalırken, trastuzumab dirençli hücrelerde artış göstermiştir; bu durum, terapötik adaptasyonda dinamik bir düzenleyici rolüne işaret etmektedir. Biyoinformatik ve deneysel analizler, miR-99b-5p’nin çinko parmak transkripsiyon faktörü (KLF4) ile ilişkili olduğunu ortaya koymuştur. Hücre temelli analizlerde miR-99b-5p'nin KLF4 ve BCL2 protein düzeylerini artırarak hücre sağkalımını desteklediği ve ilaç direncine katkıda bulunduğu gözlemlenmiştir. Mekanistik olarak, miR-99b-5p’nin hedeflediği TRAF7 olarak bilinen E3 ubikütin ligazın KLF4’ün ubikütinasyonu aracılı yıkımını düzenlediği; TRAF7’nin baskılanmasıyla KLF4 ubikütinasyonunun azaldığı ve protein stabilitesinin arttığı belirlenmiştir.
Sonuç
miR-99b-5p/TRAF7/KLF4 ekseni, Luminal B meme kanserinde post-transkripsiyonel ve ubikütin aracılı mekanizmalarla tedavi direncinin gelişiminde rol oynamaktadır. Bu düzenleyici ağın hedeflenmesi, tedaviye direnç gelişimini engellemeye yönelik yeni terapötik stratejilerin geliştirilmesine katkı sağlayabilir. Bulgular, bu eksenin daha kapsamlı fonksiyonel ve çoklu omik yaklaşımlarla incelenmesini gerekli kılmaktadır.
Anahtar Kelimeler:
Luminal meme kanseri, miR-99b-5p, transkripsiyon sonrası regülasyon ve ilaç yanıtı
Kaynaklar
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