Fetal macrosomia and sex differences in the influence of modifying factors on transplacental carcinogenesis.
Differences in cancer frequency between men and women are well known. Sexual dimorphism is also observed in the development of some experimental tumours, including those induced transplacentally. Differences in the production and binding of sex hormones by target tissues are evidently not the only cause of sexual dichotomy in the action of modifying factors on transplacental carcinogenesis. In our experiments, the average weight of newborn rats treated with glucose during intrauterine life from day 7 to 20 of gestation exceeded that of control animals, and rats exposed transplacentally to N-methyl-N-nitrosourea (MNU) on day 21 of gestation in combination with glucose (beginning from day 7 of prenatal life to 1.5 months after delivery) had a significantly increased tumour frequency. In males, there was an increased frequency of neoplasms of the nervous system and kidneys, which are typical transplacental carcinogenic effects of MNU; however, in females, neoplasms were induced in other organs and tissues, mainly the mammary gland and pituitary body. Thus, fetal macrosomia acts as a modifying factor in transplacental carcinogenesis also by determining the tumour spectrum in females and males and not only in increasing tumour frequency. The possible causes of these differences and perspectives for further research are discussed.
Berstein
L M
LM
N.N. Petrov Research Institute of Oncology, Leningrad, USSR.
Alexandrov
V A
VA
D000818:Animals; D005260:Female; D005320:Fetal Macrosomia / Q000139:chemically induced / Q000150:complications*; D005947:Glucose; D008297:Male; D008770:Methylnitrosourea; D009374:Neoplasms, Experimental / Q000139:chemically induced / Q000196:embryology / Q000209:etiology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012737:Sex Factors
D008770:Methylnitrosourea; D005947:Glucose