Ja. Mol et al., GROWTH-HORMONE MESSENGER-RNA IN MAMMARY-GLAND TUMORS OF DOGS AND CATS, The Journal of clinical investigation, 95(5), 1995, pp. 2028-2034
We have shown recently that in the dog progestin administration result
s in mammary production of immunoreactive growth hormone (GH). At pres
ent me demonstrate the expression of the gene encoding GH in the mamma
ry gland of dogs and cats using reverse-transcriptase PCR. GH mRNA was
found in the great majority of normal mammary tissues as well as beni
gn and malignant mammary tumors of the dog and was associated with the
presence of immunoreactive GH in cryostat sections, The mammary PCR p
roduct proved to be identical to that of the pituitary. The highest ex
pression levels were found after prolonged treatment with progestins.
In carcinomas GH mRNA was also found in progesterone receptor-negative
tissue samples, indicating that after malignant transformation GH gen
e expression may become progestin independent. GH mRNA was also presen
t in mammary tissues of cats with progestin-induced fibroadenomatous c
hanges. It is concluded that GH gene expression occurs in normal, hype
rplastic, and neoplastic mammary tissue of the dog, The expression in
normal tissue is stimulated by progestins and might mediate the proges
tin-stimulated development of canine mammary tumors. The demonstration
of progestin-stimulated GH expression in mammary tissue of cats indic
ates that the phenomenon is more generalized among mammals.