Is the Transcription Factor NANOG Involved in Placental Aging?

Problem: Accelerated placental aging is linked to abnormal fetal growth, preeclampsia (PE), and preterm birth (PTB). NANOG, a transcription factor, is known for its role in cellular reprogramming, self-renewal, and clonogenic growth. Its expression is regulated by Kruppel-like factor 4 (KLF4), which functions as both a transcriptional activator and repressor. This study evaluated the KLF4-NANOG pathway in placental samples from normal pregnancies (NP) as well as those with PE, fetal growth restriction (FGR), and PTB. Method of Study: Placental samples from NP pregnancies and those with PE, FGR, and PTB were analyzed for NANOG and KLF4 expression using western blotting and immunohistochemistry. Results: NANOG protein expression was significantly increased in placentas from PE, FGR, and PTB compared to NP (fold changes vs. NP: PE 2.48 ± 0.3, p = 0.002; FGR 1.64 ± 0.16, p = 0.03; PTB 6.03 ± 3.35, p = 0.01). Similarly, KLF4 protein expression was elevated in PE, FGR, and PTB placentas compared to NP (fold changes vs. NP: PE 5.78 ± 0.73, p = 0.001; FGR 2.61 ± 0.43, p = 0.02; PTB 11.42 ± 2.76, p = 0.0006). Immunohistochemistry revealed strong NANOG staining in the syncytiotrophoblast tissue of PE, FGR, and PTB samples, especially in extravillous trophoblasts, compared to NP placentas. Conclusions: The elevated expression of NANOG and KLF4 in abnormal placental tissues suggests their potential role as markers of enhanced placental aging and dysfunction. These findings underscore the importance of the KLF4-NANOG pathway in the pathology of PE, FGR, and PTB, providing a basis for future research into therapeutic targets for these conditions.