To study the promoter of the chicken progesterone receptor (cPR) gene and the relevance of several progestin-responsive elements therein, chimeric genes were constructed which contained the 5'-flanking region of the cPR gene linked to promoterless globin or chloramphenicol acetyltransferase sequences. Cell-specific initiation of transcription was observed in transiently transfected chicken embr...

The molecular mechanisms by which ovarian hormones stimulate growth of breast tumors are unclear. It has been reported previously that estrogens activate the signal-transducing Src/p21(ras)/Erk pathway in human breast cancer cells via an interaction of estrogen receptor (ER) with c-Src. We now show that progestins stimulate human breast cancer T47D cell proliferation and induce a similar rapid ...

Estrogens and artificial progestins used in hormone replacement therapy increase breast cancer risk. This seems to be due to a promoting and not initiating effect. A synergic effect of estradiol and hyperinsulinism has been shown. Insulin plays a role in the increase of breast cancer risk when associated with android obesity, sedentariness, type II diabetes, and high glycemic index food, alcoho...

Endometriosis is a common disease with typically delayed diagnosis. Its prevalence high among adolescents pelvic pain symptom. Deposits of tissue outside uterine cavity depend on oestrogen. Progestins and oral contraceptives are not successful 1/3 symptomatic women worldwide. Pathogenesis endometriosis well understood but immune system plays role in its pathophysiology. The aetiology remains la...

Uterine decidualization is characterized by stromal cell proliferation and differentiation, which are controlled by ovarian hormones estradiol and progesterone. Here we report that the proliferative response of UIII rat uterine stromal cells to a short treatment with progestins requires active progesterone receptor (PR) and estrogen receptor beta (ERbeta) as well as a rapid and transient activa...

Sixteen steroids with different endocrine activities were administered to female rats for 6 or 7 days, in a broad range of doses. Liver growth was recorded by measuring weight and DNA contents and monooxygenase activity by assaying the turnover of five different substrates. According to their effects on these parameters steroids were assigned into one of the following three groups: (a) Estrogen...

Norethindrone (17beta-hydroxy-19-nor-17alpha-pregn-4-en-20-yn-3-one) and norethindrone acetate (17beta-acetoxy-19-nor-17alpha-pregn-4-en-20-yn-3-one) interfered to a varying degree, by competitive inhibition, with the binding of progesterone and oestradiol to respective cytoplasmic receptors in the human uterus. Progesterone binding to 4S macromolecule was saturable and co-specific for progesti...

Because progesterone exerts its effects mainly via estrogen-dependent progesterone receptor (PgR), the expression of progesterone's effects may be overshadowed by the priming effect of estrogen. PgR expression vectors were transfected into estrogen receptor (ER)-alpha and PgR-negative breast cancer cells MDA-MB-231; thus the functions of progesterone could be studied independent of estrogens an...

Controversial results obtained from human and animal studies on the prevention of heart disease by estrogens and progestins warrant a better understanding of nuclear hormone receptor function and interaction. To address this issue and taking into account that effects of synthetic progestins are not only referable to action through the progesterone receptor but may also be mediated by other ster...

Clinical data suggest that progestins have chemopreventive properties in the development of colorectal cancer. We set out to examine a potential protective effect of progestins and progesterone signaling on colon cancer development. In normal and neoplastic intestinal tissue, we found that the progesterone receptor (PR) is not expressed. Expression was confined to sporadic mesenchymal cells. To...