title: Cystatin B as a potential diagnostic biomarker in ovarian clear cell carcinoma.
abstract: Epithelial ovarian cancer (EOC) consists of four major subtypes: clear cell carcinoma (CCC), endometrioid adenocarcinoma (EA), mucinous adenocarcinoma (MA) and serous adenocarcinoma (SA). Relative to the other subtypes, the prognosis of CCC is poor due to a high recurrence rate and chemotherapy resistance, but CCC-specific biomarkers have yet to be identified. With the aim of identifying diagnostic and treatment biomarkers for CCC, we analyzed 96 cases of EOC (32 CCC, 13 EA, 19 MA, 32 SA) using liquid chromatography/mass spectrometry (LC/MS) followed by immunohistochemistry (IHC) and quantitative reverse transcription PCR (RT-qPCR). Semi-quantification of protein differences between subtypes showed upregulation of 150 proteins and downregulation of 30 proteins in CCC relative to the other subtypes. Based on hierarchical clustering that revealed a marked distinction in the expression levels of cystatin B (CYTB) and Annexin A4 (ANXA4) in CCC relative to the other subtypes, we focused the study on CYTB and ANXA4 expression in EOCs by IHC, RT-qPCR and western blot analyses using tissue specimens and cultured cells. As a result, compared to the other subtypes, CCC showed significantly high expression levels of CYTB and ANXA4 in the analyses. To examine the possibility of CYTB and ANXA4 as serum diagnostic biomarkers of CCC, we checked the protein levels in conditioned media and cell lysates using culture cells. Compared with the other subtypes, CCC cell lines showed a significantly higher level of expression of CYTB in both conditioned media and cell lysates, while ANXA4 showed a higher level of expression in cell lysates only. Our results demonstrate that CYTB and ANXA4 overexpression may be related to carcinogenesis and histopathological differentiation of CCC. CYTB may be a secreted protein, and may serve as a potential serum diagnostic biomarker of CCC, while ANXA4 may be useful as an intracellular marker.
authors: Department of Integrated Diagnostic Pathology, Nippon Medical School, Tokyo 113‑8602, Japan.
authors: Akane
authors: A
authors: Takaya
authors: Department of Integrated Diagnostic Pathology, Nippon Medical School, Tokyo 113‑8602, Japan.
authors: Wei-Xia
authors: WX
authors: Peng
authors: Department of Integrated Diagnostic Pathology, Nippon Medical School, Tokyo 113‑8602, Japan.
authors: Kousuke
authors: K
authors: Ishino
authors: Department of Integrated Diagnostic Pathology, Nippon Medical School, Tokyo 113‑8602, Japan.
authors: Mitsuhiro
authors: M
authors: Kudo
authors: School of Pharmacy, Kinki University, Osaka 577‑8502, Japan.
authors: Tetsushi
authors: T
authors: Yamamoto
authors: Department of Integrated Diagnostic Pathology, Nippon Medical School, Tokyo 113‑8602, Japan.
authors: Ryuichi
authors: R
authors: Wada
authors: Division of Reproductive Medicine, Perinatology and Gynecologic Oncology, Graduate School of Medicine, Nippon Medical School, Tokyo 113‑8603, Japan.
authors: Toshiyuki
authors: T
authors: Takeshita
authors: Department of Integrated Diagnostic Pathology, Nippon Medical School, Tokyo 113‑8602, Japan.
authors: Zenya
authors: Z
authors: Naito
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000097:blood / Q000175:diagnosis* / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017314:Annexin A4 / Q000235:genetics / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid / Q000379:methods; D017077:Culture Media, Conditioned / Q000494:pharmacology; D055313:Cystatin B / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000473:pathology*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D055815:Young Adult
chemical_list: D017314:Annexin A4; D014408:Biomarkers, Tumor; C524994:CSTB protein, human; D017077:Culture Media, Conditioned; D055313:Cystatin B