title: Characterization of mammary adenocarcinomas in male rats after N-methyl-N-nitrosourea exposure--Potential for human male breast cancer model.
abstract: The frequency of breast cancer in men is extremely rare, reported to be less than 1% and there is currently no available animal model for male mammary tumors. We compared the characteristics of various immunohistochemical markers in N-methyl-N-nitrosourea (MNU)-induced mammary adenocarcinomas in male and female Crj:CD(SD)IGS rats including: estrogen receptor α (ER), progesterone receptor (PgR), androgen receptor (AR), receptor tyrosine-protein kinase erbB-2 (HER2), GATA binding protein 3 (GATA3), and proliferating cell nuclear antigen (PCNA). Female mammary adenocarcinomas were strongly positive in the nuclei of tumor cells for PCNA and ER (100%) with only 60% and 53% expressing PgR and GATA3, respectively. 100% of male adenocarcinomas also exhibited strongly positive expression in the nuclei of tumor cells for PCNA, with 25% expressing AR and only 8% showing positivity for ER. Male carcinomas did not express PgR or GATA3 and none of the tumors, male or female, were positive for HER2. Based on the observed ER and PgR positivity and HER2 negativity within these tumors, MNU-induced mammary adenocarcinomas in female rats appear to be hormonally dependent, similar to human luminal A type breast cancer. In contrast, MNU-induced mammary adenocarcinomas in male rats showed no reactivity for ER, PgR, HER2 or GATA3, suggesting no hormonal dependency. Both male and female adenocarcinomas showed high proliferating activity by PCNA immunohistochemistry. Based on our literature review, human male breast cancers are mainly dependent on ER and/or PgR, therefore the biological pathogenesis of MNU-induced male mammary cancer in rats may differ from that of male breast cancer in humans.
authors: Department of Pathology II, Kansai Medical University, 2-5-1 Shin-machi, Hirakata, Osaka 573-1010, Japan. Electronic address: yoshizak@hirakata.kmu.ac.jp.
authors: Katsuhiko
authors: K
authors: Yoshizawa
authors: Department of Pathology II, Kansai Medical University, 2-5-1 Shin-machi, Hirakata, Osaka 573-1010, Japan.
authors: Michiko
authors: M
authors: Yuki
authors: Department of Pathology II, Kansai Medical University, 2-5-1 Shin-machi, Hirakata, Osaka 573-1010, Japan; Division of Diagnostic Cytopathology and Histopathology, Kansai Medical University Takii Hospital, Fumizono 10-15, Moriguchi, Osaka 570-8507, Japan.
authors: Yuichi
authors: Y
authors: Kinoshita
authors: Department of Pathology II, Kansai Medical University, 2-5-1 Shin-machi, Hirakata, Osaka 573-1010, Japan.
authors: Yuko
authors: Y
authors: Emoto
authors: Department of Pathology II, Kansai Medical University, 2-5-1 Shin-machi, Hirakata, Osaka 573-1010, Japan.
authors: Takashi
authors: T
authors: Yuri
authors: Division of Diagnostic Cytopathology and Histopathology, Kansai Medical University Takii Hospital, Fumizono 10-15, Moriguchi, Osaka 570-8507, Japan.
authors: Nobuaki
authors: N
authors: Shikata
authors: Cellular & Molecular Pathology Branch, National Institute of Environmental Health Sciences, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA.
authors: Susan A
authors: SA
authors: Elmore
authors: Department of Pathology II, Kansai Medical University, 2-5-1 Shin-machi, Hirakata, Osaka 573-1010, Japan.
authors: Airo
authors: A
authors: Tsubura
mesh_terms: D000230:Adenocarcinoma / Q000139:chemically induced* / Q000473:pathology; D000818:Animals; D018567:Breast Neoplasms, Male / Q000139:chemically induced* / Q000473:pathology; D002273:Carcinogens / Q000494:pharmacology*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D008297:Male; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000473:pathology; D015674:Mammary Neoplasms, Animal / Q000139:chemically induced* / Q000473:pathology; D008770:Methylnitrosourea / Q000494:pharmacology*; D051381:Rats
chemical_list: D002273:Carcinogens; D008770:Methylnitrosourea
keywords: Breast cancer; Immunohistochemistry; Male rat; Mammary adenocarcinoma; N-methyl-N-nitrosourea