ORIGINAL ARTICLE Bali Medical Journal (Bali Med J) 2019, Volume 8, Number 1: 128-133 P-ISSN.2089-1180, E-ISSN.2302-2914 128 Open access: www.balimedicaljournal.org and ojs.unud.ac.id/index.php/bmj CrossMark Published by DiscoverSys ABSTRACT Background: The development of a novel biological marker for diagnosis and prognosis prediction of epithelial ovarian cancer (EOC) remains urgent. Current literature shows that microRNA-21 (miRNA-21/miR-21) are involved in the growth, metastasis, and apoptosis of cancer cells. This study aims to determine the difference in miR-21 expression between stages, histopathology type, and residual tumor after surgery in EOC patients. Methods: A cross sectional study was conducted among 40 EOC patients. Blood samples were taken prior to surgery, and when the pathological anatomy result confirmed the presence of EOC, the RNA was then isolated. Based on the RNA, the cDNA was synthesized and run through qPCR. All data were analyzed using the GenEx analyzing software. Results: The expression of miR-21 in the advanced stage was 1.36 up-fold compared to the early stage (p=0.52). The expression of miR-21 in type II EOC was 1.33 up-fold compared to type I EOC (p=0.56). The expression of miR-21 in residual tumor >1cm after surgery was 1.30 up-fold compare to residual tumor after surgery < 1cm (p=0.59) Conclusion: There was no significant increase in the expression of circulating miR-21 between stages, histopathology type, and residual tumor after surgery in EOC patients in this study. Circulating miR-21 may be a promising biomarker for EOC. Nevertheless, further studies with larger sample sizes are still needed to address the discrepancy and clarify the prognostic value of circulating miR-21. Keywords: Circulating miR-21, epithelial ovarian cancer, non-invasive biomarker Cite this Article: Trirahmanto, A., Haryana, S.M., Hakimi, M., Pradjatmo, H. 2019. The role of circulating MicroRNA-21 (miR-21) in epithelial ovarian cancer. Bali Medical Journal 8(1): 128-133. DOI:10.15562/bmj.v8i1.1323 The role of circulating MicroRNA-21 (miR-21) in epithelial ovarian cancer Addin Trirahmanto, 1* Sofa Mubarika Haryana, 2 Moh Hakimi, 1 Heru Pradjatmo 1 INTRODUCTION Of all gynecological cancers, ovarian cancer is associated with the worst prognosis and the high- est mortality rate. Ovarian cancer is the seventh most frequent cancer worldwide, with 238,700 new cases in 2012, and is the eighth most common cause of cancer mortality, with 151,900 deaths. 1 In developed countries, ovarian cancer has the highest mortality rate compared to other types of cancers, while it is the second most common cause of cancer-related death in developing countries, following cervix cancer. In 2018, there will be approximately 22.240 new cases of ovarian cancer diagnosed and 12.070 ovarian cancer deaths in the United States. Ovarian cancer accounts for 2.5% of all malignancies among females but 5% female deaths because of low survival rates, largely driven by late-stage diagnoses. 2 Te most common ovarian cancer is the epithelial subtype. 3 A study of epithelial cancer survival rate in Dr. Cipto Mangunkusumo Hospital showed that the survival rate in the frst year was 95.8, second year 86.8%, while the percentage decreased in the third and fourth year becoming 77%. Te survival rate based on the stage of the ovarian cancer was 32.7% (44.9%) for the early stage and 67.3% (55.1%) for the advanced stage. Te highest incidence of ovarian cancer in Dr. Cipto Mangunkusumo Hospital belongs to the age of reproductive women (≤ 55 years old), particularly nulliparous women. Most ovarian cancer cases are diagnosed in the advanced stage. 4 Te primary reasons for this poor prognosis include the late stage of presentation due to the absence of symptoms, the lack of efective screening tools, and the development of recurrent disease that is resistant to chemotherapy. Currently, there are no efective biomarkers for ovarian cancer prognosis that can provide infor- mation regarding the clinical treatment for ovarian cancer. Te circulating biomarkers used in current clinical practice lack sufcient accuracy. Terefore, there is still a great need for simple and reliable biomarkers to predict the outcome of ovarian cancer patients. MicroRNAs (miRNAs) are endogenous, small non-coding 18–25 nucleotide RNAs. Tese miRNAs could be post-transcriptional gene regula- tors that paired to complementary sequences in the 3′ untranslated region (3′ UTR) of target mRNAs, leading to mRNA degradation or translational repression. Not only do these miRNAs regulate gene expression, but they are also involved in various biogenesis that is associated with carcino- geneses, such as cell proliferation, cell cycle, apop- tosis, angiogenesis, invasion, and metastasis. In 1 Department of Obstetrics and Gynecology, Faculty of Medicine, Public Health, and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia. 2 Department of Histology and Cellular Biology, Faculty of Medicine, Public Health, and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia. * Corresponding to: Addin Trirahmanto; Department of Obstetrics and Gynecology, Faculty of Medicine, Public Health, and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia; addinspog@ugm.ac.id Received: 2018-09-07 Accepted: 2018-10-14 Published: 2019-4-1