title: Ki-67 and minichromosome maintenance-7 (MCM7) expression in canine pituitary corticotroph adenomas.
abstract: Pituitary-dependent hyperadrenocorticism (PDH) caused by pituitary corticotroph adenoma is a common endocrine disorder in dogs. The ratio between pituitary height and the area of the brain (P/B) has been used to evaluate the pituitary size. A P/B ratio > 0.31 indicates an enlarged pituitary, whereas a P/B ratio ≤ 0.31 indicates a nonenlarged pituitary. The aim of this study was to investigate the expression of proliferation markers Ki-67 and minichromosome maintenance-7 (MCM7) in canine corticotroph adenomas in enlarged and in nonenlarged pituitaries and to evaluate their relation with the size of canine pituitary corticotroph adenomas. Ki-67 and MCM7 expression in ACTH-positive tumor cells was determined by dual-labeling immunohistochemistry in resected corticotroph adenomas from 15 dogs with PDH. The mean ± SD Ki-67 labeling index (LI) was 0.55% ± 0.59% in corticotroph adenomas with nonenlarged pituitaries and 1.6% ± 0.6% in adenomas with enlarged pituitaries. The MCM7 LI in corticotroph adenomas with nonenlarged pituitaries and in adenomas with enlarged pituitaries was 2.9% ± 2.2% and 10.9% ± 3.7%, respectively. The Ki-67 LI and MCM7 LI were significantly greater in the adenomas with enlarged pituitaries than in the adenomas with nonenlarged pituitaries (P < 0.01 and P < 0.01, respectively). The MCM7 LI was significantly greater than the Ki-67 LI in adenomas (P < 0.01). The Ki-67 LI was positively correlated with the MCM7 LI (r = 0.820, P < 0.01), and the P/B ratio was positively correlated with the Ki-67 LI (r = 0.560, P = 0.03) and the MCM7 LI (r = 0.854, P < 0.01). In conclusion, canine corticotroph adenomas in enlarged pituitaries show greater proliferation potential than do adenomas in nonenlarged pituitaries. MCM7 expression was significantly greater than Ki-67 expression in canine pituitary corticotroph adenomas. Thus, MCM7 may be superior to Ki-67 as a proliferation marker in pituitary tumors.
authors: Division of Veterinary Surgery, Department of Veterinary Science, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Musashino-shi, Tokyo, Japan. hiro-ish@pp.iij4u.or.jp
authors: H
authors: H
authors: Ishino
authors: Y
authors: Y
authors: Hara
authors: S
authors: S
authors: Takekoshi
authors: T
authors: T
authors: Teshima
authors: A
authors: A
authors: Teramoto
authors: R Y
authors: RY
authors: Osamura
authors: M
authors: M
authors: Tagawa
mesh_terms: D049913:ACTH-Secreting Pituitary Adenoma / Q000378:metabolism / Q000662:veterinary*; D000236:Adenoma / Q000378:metabolism / Q000662:veterinary; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004283:Dog Diseases / Q000378:metabolism*; D004285:Dogs; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D019394:Ki-67 Antigen / Q000235:genetics / Q000378:metabolism*; D008297:Male; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D019394:Ki-67 Antigen; D009687:Nuclear Proteins