The aim of the study was to evaluate the potential of human breast cancer tissue to secrete growth hormone (GH), insulin-like growth factor I (IGF-I) and prolactin in response to 10(-7) M progesterone stimulation. Explants were divided according to estrogen receptor (ER)/progesterone receptor (PR) phenotype (ER(-)PR(-); ER(+)PR(-); ER(+)PR(+); ER(-)PR(+)). Our results show distinct differences in cultured breast cancer tissue responses to progesterone stimulation with regard to secretion of proliferative agents such as GH, IGF-I and prolactin. All but ER(-)PR(-) breast cancer cell types responded in vitro to progesterone stimulation with an increase in local GH secretion, while in non-malignant tissue progesterone induced local GH secretion only in PR(+) cells. Moreover, only in PR(+) cells did progesterone stimulate local IGF-I and prolactin secretion, in both malignant and non-malignant tissue. This study provides evidence for the first time that in PR(+) breast cancer tissue, progesterone may increase GH, prolactin and IGF-I secretion in both malignant and surrounding non-malignant tissue. These hormones may act as local growth factors that stimulate the proliferation of mammary tumors.
The aim of the present study was to compare the ability of natural progesterone and synthetic progestins to stimulate local growth hormone (GH) and insulin-like growth factor I (IGF-I) secretion by breast cancer explants. Explants obtained during surgery were divided according to their estrogen/progesterone receptor phenotype - ER(+)PR(-); ER(+)PR(+); ER(-)PR(+) - as determined by immunocytochemistry. Natural progesterone (10(-5) mol/l) and synthetic progestins (cyproterone acetate (5 x 10(-7) mol/l), norethindrone (10(-5) mol/l), medroxyprogesterone acetate (10(-7) mol/l), and levonorgestrel (10(-7) mol/l) were tested in vitro for their ability to induce secretion of proliferation-promoting agents such as human GH (hGH) and IGF-I. All hormone-dependent breast cancer cell types responded to progesterone stimulation with increased local hGH secretion, while in the non-malignant tissue this effect was observed only in PR(+) cells. Moreover, progesterone in only PR(+) cells in vitro stimulated local IGF-I secretion by both malignant and non-malignant tissue. Medroxyprogesterone and levonorgestrel increased GH secretion by both malignant and non-malignant ER(-)PR(+) breast cancer explants, while cyproterone stimulated it only in non-malignant tissue. None of the synthetic progestins tested in this experiment exerted an effect on GH secretion by both malignant and non-malignant tissue of ER(+) breast cancer explants. The present data additionally showed that, apart from cyproterone, which increased IGF-I secretion in the same manner as progesterone by both malignant and non-malignant ER(-)PR(+) breast explants, other progestins tested had either no effect on IGF-I local secretion or decreased it. Medroxyprogesterone and levonorgestrel induced a decrease in IGF-I secretion noted in ER(+) explants of non-malignant tissue and in malignant ER(-)PR(+) breast tissue. All progestins tested decreased IGF-I secretion by malignant ER(+)PR(+) explants. Taken together, the tested synthetic progestins widely used as oral contraceptives and in hormone replacement therapy were less potent than progesterone in inducing secretion of proliferation-promoting agents such as hGH and IGF-I in ER-containing breast tissue. Despite the lack of confirmation of the link between the use of progestins and breast cancer risk, patients should be informed that the use of certain estrogen/progestin preparations is of no influence on breast cancer risk while others may increase it.
Fat-soluble vitamin deficiency remains a challenge in cystic fibrosis (CF), chronic pancreatitis, and biliary atresia. Liposomes and cyclodextrins can enhance their bioavailability, thus this multi-center randomized placebo-controlled trial compared three-month supplementation of fat-soluble vitamins in the form of liposomes or cyclodextrins to medium-chain triglycerides (MCT) in pancreatic-insufficient CF patients. The daily doses were as follows: 2000 IU of retinyl palmitate, 4000 IU of vitamin D3, 200 IU of RRR-α-tocopherol, and 200 µg of vitamin K2 as menaquinone-7, with vitamin E given in soybean oil instead of liposomes. All participants received 4 mg of β-carotene and 1.07 mg of vitamin K1 to ensure compliance with the guidelines. The primary outcome was the change from the baseline of all-trans-retinol and 25-hydroxyvitamin D3 concentrations and the percentage of undercarboxylated osteocalcin. Out of 75 randomized patients (n = 28 liposomes, n = 22 cyclodextrins, and n = 25 MCT), 67 completed the trial (89%; n = 26 liposomes, n = 18 cyclodextrins, and n = 23 MCT) and had a median age of 22 years (IQR 19–28), body mass index of 20.6 kg/m2 [18.4–22.0], and forced expiratory volume in 1 s of 65% (44–84%). The liposomal formulation of vitamin A was associated with the improved evolution of serum all-trans-retinol compared to the control (median +1.7 ng/mL (IQR −44.3–86.1) vs. −38.8 ng/mL (−71.2–6.8), p = 0.028). Cyclodextrins enhanced the bioavailability of vitamin D3 (+9.0 ng/mL (1.0–17.0) vs. +3.0 ng/mL (−4.0–7.0), p = 0.012) and vitamin E (+4.34 µg/mL (0.33–6.52) vs. −0.34 µg/mL (−1.71–2.15), p = 0.010). Liposomes may augment the bioavailability of vitamin A and cyclodextrins may strengthen the supplementation of vitamins D3 and E relative to MCT in pancreatic-insufficient CF but further studies are required to assess liposomal vitamin E (German Clinical Trial Register number DRKS00014295, funded from EU and Norsa Pharma).
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