Objective The objective of this study was to evaluate the prognostic significance of NANOG expression in ovarian serous carcinoma.
Methods The expression of NANOG was evaluated in 6 ovarian carcinoma cell lines, paclitaxel-resistant SKOV3 cells, and SKOV3 spheroid cells with semiquantitative reverse transcription–polymerase chain reaction and Western blotting. NANOG expression was also measured immunohistochemically in a tissue microarray containing ovarian tissues from 74 patients with ovarian serous carcinoma and 24 with ovarian serous cystadenoma. Each sample was scored based on signal intensity and proportion, and a score greater than 4 was considered “positive.”
Results NANOG mRNA expression was variable in different ovarian cancer cell lines. The mRNA level of NANOG was increased in the paclitaxel-resistant SKOV3 cells and SKOV3 spheroid cells compared with that in the SKOV3 cells. NANOG expression was positive in 21.6% of 74 ovarian serous carcinoma tissues, but none of the ovarian serous cystadenoma tissues were positive. Positive NANOG expression was associated with residual tumor size after surgery (P = 0.032). The overall survival of the patients with positive NANOG expression was poorer than that of the patients with negative NANOG expression (P = 0.020). In patients with stage I and II disease, positive NANOG expression was independently associated with shorter overall survival compared with negative NANOG expression (40 vs 120 months, respectively; P = 0.031).
Conclusions Positive NANOG expression is associated with poor prognosis of ovarian serous carcinoma. NANOG has potential as a predictor of survival for patients with ovarian carcinomas and may be involved in the mechanism of chemoresistance.
- Cancer stem cell
- Ovarian cancer
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This study was supported by the Brain Korea 21 project for Medical Sciences of Yonsei University and a grant of the Korea Healthcare technology R&D Project, Ministry for Health, Welfare & Family Affairs, Republic of Korea (A084120).
The authors declare no conflicts of interest.