Adrenal regulation of mammary tumorigenesis in female Sprague-Dawley rats: histopathology of mammary tumors

Mammary tumors induced in female Sprague-Dawley rats by feeding 7,12-dimethylbenz(a)anthracene (DMBA; 20 mg/100 g body weight) were classified according to histological criteria of tissue differentiation, cellular atypia, and evidence of invasion. The 549 tumors could be placed in three categories,...

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Bibliographic Details
Published in:Cancer research (Chicago, Ill.) Ill.), 1988-07, Vol.48 (13), p.3808-3815
Main Authors: CARTER, J. H, CARTER, H. W
Format: Article
Language:English
Subjects:
9,10-Dimethyl-1,2-benzanthracene
Adrenal Glands - physiopathology
Adrenalectomy
Age Factors
Animal tumors. Experimental tumors
Animals
Biological and medical sciences
Carcinoma - pathology
Experimental genital and mammary tumors
Female
Mammary Glands, Animal - cytology
Mammary Neoplasms, Experimental - pathology
Mammary Neoplasms, Experimental - physiopathology
Medical sciences
Methylprednisolone - pharmacology
Neoplasm Transplantation
Pituitary Gland - transplantation
Rats
Time Factors
Tumors
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Summary:Mammary tumors induced in female Sprague-Dawley rats by feeding 7,12-dimethylbenz(a)anthracene (DMBA; 20 mg/100 g body weight) were classified according to histological criteria of tissue differentiation, cellular atypia, and evidence of invasion. The 549 tumors could be placed in three categories, nodular hyperplasia, nodular hyperplasia with atypia, and carcinoma, and combinations of all three. Although tumors classified histologically as carcinomas did not metastasize, upon transplantation to the kidney capsule, a tumor classified as a carcinoma grew for eight generations and metastasized. Tumor heterogeneity was a common finding in DMBA-initiated tumors. Carcinomas were an early lesion. As the length of time between DMBA treatment and sacrifice increased, more tumors with areas of carcinoma were found. Therefore, DMBA-initiated tumors progressed to carcinomas either soon after initiation or later by development within nodular hyperplasias. In 4 separate groups of animals (74 adrenalectomized rats and 90 intact rats), postinitiation adrenalectomy increased the numbers of carcinomas compared to intact animals. This effect was consistently seen in the cervical and thoracic mammary glands. We propose that the mechanism for enhancement of progression to greater malignancy by adrenalectomy may be inhibition of differentiation of initiated cells in the absence of glucocorticoids.
ISSN:0008-5472
1538-7445