Mutational analysis of FOXL2 p.C134W and expression of bone morphogenetic protein 2 in Japanese patients with granulosa cell tumor of ovary

Aim To assess whether FOXL2 p.C134W mutation may play a role in the development of human ovarian tumors in the Japanese, we investigated the FOXL2 codon 134 mutation and protein expression of inhibin-α, bone morphogenetic protein 2 (BMP2) and follistatin (FST) in Japanese patients with granulosa cell tumor (GCT) of the ovary and other ovarian tumors. Methods We analyzed 114 tumor tissues from ovarian tumors, including 44 adult-type and two juvenile-type GCT of the ovary and 68 ovarian tumors by DNA sequencing. Immunohistochemistry was also performed in the adult and juvenile GCT tissues by immunostaining inhibin-α, BMP2 and FST. Results We found the FOXL2 p.C134W mutation in 27 out of 44 (61.4%) adult-type GCT of the ovary, but none in other ovarian tumors. Histologically, all of the adult-type GCT sections were positive for inhibin-α, and the expression of BMP2 and FST was detected in 14 of 44 (31.8%) and zero of 47 (0%), respectively. No significant differences regarding the diagnosed age, preoperative serum carbohydrate antigen 125 levels, or BMP2 immunopositivity between the FOXL2 p.C134W mutation-positive and mutation-negative were found in the adult-type GCT patients. Conclusion Our findings suggest that FOXL2 p.C134W mutation-positive adult-type GCT of the ovary may not be common in the Japanese as compared to the previous data.