*Article* **Circulating Exosomal miR-1290 for Diagnosis of Epithelial Ovarian Cancer**

**Hyeji Jeon 1,2,†, Su Min Seo 3,\* ,†, Tae Wan Kim 2,4, Jaesung Ryu 2,4, Hyejeong Kong 2,4, Si Hyeong Jang <sup>5</sup> , Yong Soo Jang <sup>1</sup> , Kwang Seock Kim <sup>2</sup> , Jae Hoon Kim <sup>6</sup> , Seongho Ryu 3,\* and Seob Jeon 1,2,\***

	- angelkonghj@gmail.com (H.K.); kimks5005gt@gmail.com (K.S.K.)

**Abstract:** The aim of the study was to develop a new diagnostic biomarker for identifying serum exosomal miRNAs specific to epithelial ovarian cancer (EOC) and to find out target gene of the miRNA for exploring the molecular mechanisms in EOC. A total of 84 cases of ovarian masses and sera were enrolled, comprising EOC (*n* = 71), benign ovarian neoplasms (*n* = 13). We detected expression of candidate miRNAs in the serum and tissue of both benign ovarian neoplasm group and EOC group using real-time polymerase chain reaction. Immunohistochemistry were constructed using formalin fixed paraffin embedded (FFPE) tissue to detect expression level of suppressor of cytokine signaling 4 (SOCS4). In the EOC group, miRNA-1290 was significantly overexpressed in serum exosomes and tissues as compared to benign ovarian neoplasm group (fold change ≥ 2, *p* < 0.05). We observed area under the receiver operating characteristic curve (AUC) for miR-1290, using a cut-off of 0.73, the exosomal miR-1290 from serum had AUC, sensitivity, and specificity values of 0.794, 69.2 and 87.3, respectively. In immunohistochemical study, expression of SOCS4 in EOC was lower than that in benign ovarian neoplasm. Serum exosomal miR-1290 could be considered as a biomarker for differential diagnosis of EOC from benign ovarian neoplasm and SOCS4 might be potential target gene of miR-1290 in EOC.

**Keywords:** ovarian cancer; exosomal microRNA; biomarker; early diagnosis
