Mammary gland carcinoma-related increase of type I iodothyronine 5'-deiodinase activity in Sprague-Dawley rats.
Type I, iodothyronine 5'-deiodinase (5'-DI) catalyses deiodination of the prohormone thyroxine (T4) to the metabolically active 3,5,3'-triiodo-L-thyronine (T3). The present study was undertaken to investigate the activity of 5'-DI in rat mammary gland tumours representing various combinations of histologically defined papillary, cribriform or comedo patterns of ductal carcinomas. Female Sprague-Dawley rats were given two doses 50 mg x kg(-1) 1-methyl-1-nitrosourea (MNU) in abdominal parts on the 52nd day and 113th day of age. We have found that in comparison with non-lactating mammary gland, the activity of 5'-DI in all mammary gland tumours studied was significantly (p < 0.0001) increased and that the 5'-DI activity, expressed as pmol of 125I- released per min and per mg of protein, in malignant mammary gland tumours was found to be at least two order higher than that of intact mammary non-lactating gland. From our data, we suggest that thyroid hormone in mammary gland tumours might play a significant role to support high energetic expenditure of neoplastic tissues.
Macejová
D
D
Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava.
Líska
J
J
Brtko
J
J
D000818:Animals; D002273:Carcinogens; D002277:Carcinoma / Q000201:enzymology; D005260:Female; D007453:Iodide Peroxidase / Q000378:metabolism; D015674:Mammary Neoplasms, Animal / Q000201:enzymology* / Q000473:pathology; D008770:Methylnitrosourea; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D002273:Carcinogens; D008770:Methylnitrosourea; D007453:Iodide Peroxidase