Estrogen-Responsive Finger Protein as a New Potential Biomarker for Breast Cancer Takashi Suzuki, 1 Tomohiko Urano, 3 Tohru Tsukui, 4 Kuniko Horie-Inoue, 4 Takuya Moriya, 1 Takanori Ishida, 2 MasamiMuramatsu, 4 Yasuyoshi Ouchi, 3 Hironobu Sasano, 1 and Satoshi Inoue 3,4 Abstract Purpose: Estrogen-responsivefingerprotein(Efp)isamemberofRINGfinger-Bbox-CoiledCoil family andis also a downstream target of estrogen receptor a. Previously, Efp was shown to mediateestrogen-inducedcellgrowth,whichsuggestspossibleinvolvementinthe development of human breast carcinomas. In this study, we examined expression of Efp in breast carcinoma tissuesandcorrelatedthesefindingswithvariousclinicopathologicvariables. Experimental Design: Thirty frozen specimens of breast carcinomas were used for immuno- histochemistry and laser capture microdissection/real-time PCRof Efp. Immunohistochemistry for Efp was also done in151breast carcinoma specimens fixed with formalin and embedded in paraffinwax. Results: Efp immunoreactivity was detected in breast carcinoma cells and was significantly associated with the mRNA level ( n = 30). Efp immunoreactivity was positively associated with lymph node status or estrogen receptor a status and negatively correlated withhistologic grade or14-3-3j immunoreactivity ( n =151). Moreover, Efpimmunoreactivity was significantlycorre- lated with poor prognosis of breast cancer patients, and multivariate analyses of disease-free survivalandoverallsurvivalfor151breastcancerpatients showedthatEfpimmunoreactivity was theindependentmarker. Conclusions: Our data suggest that Efp immunoreactivity is a significant prognostic factor in breast cancer patients.These findings may account for an oncogenic role of Efp in the tumor progressionofbreastcarcinoma. Breast cancer is the most common type of cancer and continues to be the most frequent cause of cancer-related deaths in women in the Western world. Whether or not human primary breast cancers are estrogen dependent is a critical factor that determines patient prognosis and availability of antiestro- genic endocrine therapy (1). Two thirds of breast carcinomas are positive for estrogen receptor a (ERa) and a great majority of these tumors initially respond to antiestrogens such as tamoxifen and aromatase inhibitors. However, it is also true that these ERa-positive breast carcinomas frequently acquire resistance to endocrine therapy, although ERa remains to be expressed (1, 2). The molecular mechanisms through which breast carcinomas become hormone-refractory are still largely unclear. Identification and functional studies of ERa target molecules may provide a clue for understanding the mechanism that alters tumor phenotypes. We have previously isolated estrogen- responsive finger protein (Efp), which is a member of RING finger-B box-Coiled Coil family (3). Efp also is one of the downstream targets of ERa (3 – 6). Efp-deficient mice displayed underdeveloped uteri and reduced estrogen responsiveness (7), and therefore, Efp is considered to be essential for estrogen- dependent proliferation. It has also been shown that Efp promotes the growth of breast tumor by functioning as a ubiquitin ligase (E3) that targets the negative cell cycle check- point 14-3-3j (8). Expression of Efp was previously reported in breast carcino- ma tissues at mRNA (5) and protein levels (9). However, information on the expression of Efp in human breast carcinoma tissues is still very limited, and the biological significance of Efp remains unclear at this juncture. Therefore, in this study, we examined expression of Efp in 30 cases of breast carcinoma tissues using immunohistochemistry and laser capture microdissection/real-time PCR. We subsequently examined immunolocalization of Efp in 151 cases of human breast carcinoma tissues and correlated these findings with various clinicopathologic factors including clinical outcome of the patients. Human Cancer Biology Authors’Affiliations: Departmentsof 1 Pathologyand 2 Surgery, TohokuUniversity School of Medicine, Aoba-ku, Sendai, Miyagi-ken, Japan; 3 DepartmentofGeriatric Medicine, Graduate School of Medicine,The University of Tokyo, Hongo, Bunkyo- ku, Tokyo, Japan; and 4 Research Center for Genomic Medicine and Department of Molecular Biology, Saitama Medical School, Yamane, Hidaka-shi, Saitama, Japan Received1/6/05;revised6/9/05;accepted6/28/05. Grant support: Ministry of Health, Labor, andWelfare Japan, the Ministry of Education, Culture, Sports, Science and Technology Japan, the Core Research for EvolutionalScienceand Technology,andthePrincessTakamatsuCancerResearch Fund(02-23402). Thecostsofpublicationofthisarticleweredefrayedinpartbythepaymentofpage charges.This article must therefore be hereby marked advertisement in accordance with18 U.S.C. Section1734 solely toindicate this fact. Requests for reprints: Takashi Suzuki, Department of Pathology,Tohoku University School of Medicine, 2-1Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan. Phone: 81-22-717-8050; Fax: 81-22-717-8051; E-mail: t-suzuki@ patholo2.med.tohoku.ac.jp. F 2005AmericanAssociationforCancerResearch. doi:10.1158/1078-0432.CCR-05-0040 www.aacrjournals.org ClinCancerRes2005;11(17)September1,2005 6148 Research. on June 14, 2020. © 2005 American Association for Cancer clincancerres.aacrjournals.org Downloaded from