BACKGROUND: Administration of 1-methyl-1-nitrosourea (MNU) is considered a simple and rapid method for inducing breast tumors in rats. While most studies focus on the time frame of tumor development, there are little data on the development of breast tumor in relation to tumor size. Thus the current study was carried out to analyze the phenotype of MNU-induced tumors in relation to tumor size. MATERIAL/ METHODS: Twenty-one 21-day-old female Sprague Dawley rats were administered intraperitoneally with MNU at a dose of 70 mg/kg body weight. The entire palpable tumor was excised when the tumor size reached the diameters of 4.0+/-0.5 mm, 8.0+/-0.5 mm, 12.0+/-0.5 mm, and 16.0+/-0.5 mm and then subjected to histopathological assessment. RESULTS: Epithelial inclusion cysts and mammary adenomas made up most of the benign tumors, with four cases occurring together with malignant lesions. Ductal carcinoma in situ was seen in tumor sizes of 4.0+/-0.5 mm or less. Among the malignant tumors, the cribriform type was seen predominantly at tumor sizes of less than 12.0+/-0.5 mm, while those with sizes of 12.0+/-0.5 mm or greater were of papillary type. Infiltrating ductal carcinoma-no special type (IDC-NST) commonly seen in humans was also observed at tumor sizes greater than 12.0+/-0.5 mm. CONCLUSIONS: The tumors were found to be mainly of malignant type and the histological features of the induced tumors underwent changes as the tumor grew in size.
BACKGROUND: Administration of 1-methyl-1-nitrosourea (MNU) is considered a simple and rapid method for inducing breast tumors in rats. While most studies focus on the time frame of tumor development, there are little data on the development of breast tumor in relation to tumor size. Thus the current study was carried out to analyze the phenotype of MNU-induced tumors in relation to tumor size. MATERIAL/ METHODS: Twenty-one 21-day-old female Sprague Dawley rats were administered intraperitoneally with MNU at a dose of 70 mg/kg body weight. The entire palpable tumor was excised when the tumor size reached the diameters of 4.0+/-0.5 mm, 8.0+/-0.5 mm, 12.0+/-0.5 mm, and 16.0+/-0.5 mm and then subjected to histopathological assessment. RESULTS: Epithelial inclusion cysts and mammary adenomas made up most of the benign tumors, with four cases occurring together with malignant lesions. Ductal carcinoma in situ was seen in tumor sizes of 4.0+/-0.5 mm or less. Among the malignant tumors, the cribriform type was seen predominantly at tumor sizes of less than 12.0+/-0.5 mm, while those with sizes of 12.0+/-0.5 mm or greater were of papillary type. Infiltrating ductal carcinoma-no special type (IDC-NST) commonly seen in humans was also observed at tumor sizes greater than 12.0+/-0.5 mm. CONCLUSIONS: The tumors were found to be mainly of malignant type and the histological features of the induced tumors underwent changes as the tumor grew in size.
Authors: Iwona Malicka; Katarzyna Siewierska; Bartosz Pula; Christopher Kobierzycki; Dominik Haus; Urszula Paslawska; Marek Cegielski; Piotr Dziegiel; Marzena Podhorska-Okolow; Marek Wozniewski Journal: Exp Biol Med (Maywood) Date: 2015-05-19
Authors: Muhammad Shahidan Muhammad Sakri; Tengku Ahmad Damitri Al-Astani Tengku Din; Hasnan Jaafar; Vinod Gopalan; Wan Faiziah Wan Abdul Rahman Journal: Int J Immunopathol Pharmacol Date: 2022 Jan-Dec Impact factor: 3.219