[27- Hydroxycholesterol reverses estradiol induced inhibition of platelet aggregation in postmenopausal women]. / Efecto del 27- hidroxicolesterol en la acción antiplaquetaria de estradiol en mujeres postmenopáusicas.

BACKGROUND: The decline of estrogen levels increases cardiovascular risk in women. Platelets express estrogen receptors and 17ß-estradiol- (E2) can produce a protective effect on thrombus formation. The hydroxylation of cholesterol generates several sterols and 27-hydroxycholesterol (27HC) predominates in circulation. AIM: To evaluate the effect of 27HC as an endogenous antagonist of the anti-aggregating properties of E2 in platelets of postmenopausal women. MATERIAL AND METHODS: Platelet function of postmenopausal women was evaluated ex-vivo. Platelets pre-incubated with 27HC in the presence or absence of E2, were stimulated with collagen. Aggregation was evaluated using turbidimetry using a Chrono-log aggregometer. RESULTS: Collagen-stimulated platelet aggregation was significantly inhibited by E2. The inhibitory effect of E2 on collagen-stimulated platelet aggregation was significantly reversed in the presence of 27HC. CONCLUSIONS: The suppressive effect of E2 on platelet aggregation is inhibited by 27HC, which could contribute to increase cardiovascular risk in postmenopausal women.

Administration of high doses of copper to capuchin monkeys does not cause liver damage but induces transcriptional activation of hepatic proliferative responses.

Liver cells respond to copper loading upregulating protective mechanisms. However, to date, except for liver content, there are no good indicators that identify individuals with excess liver copper. We hypothesized that administering high doses of copper to young (5.5 mg Cu · kg⁻¹ . d⁻¹) and adult (7.5 mg Cu · kg⁻¹ . d⁻¹) capuchin monkeys would induce detectable liver damage. Study groups included adult monkeys (2 females, 2 males) 3-3.5 y old at enrollment treated with copper for 36 mo (ACu); age-matched controls (1 female, 3 males) that did not receive additional copper (AC); young monkeys (2 female, 2 males) treated from birth with copper for 36 mo (YCu); and young age-matched controls (2 female, 2 males) that did not receive additional copper (YC). We periodically assessed clinical, blood biochemical, and liver histological indicators and at 36 mo the hepatic mRNA abundance of MT2a, APP, DMT1, CTR1, HGF, TGFß, and NFκΒ only in adult monkeys. After 36 mo, the liver copper concentration was 4-5 times greater in treated monkeys relative to controls. All monkeys remained healthy with normal routine serum biochemical indices and there was no evidence of liver tissue damage. Relative mRNA abundance of HGF, TGFß and NFκB was significantly greater in ACu than in AC monkeys. In conclusion, capuchin monkeys exposed to copper at doses up to 50 times the current upper level enhanced expression of genes related to inflammation and injury without clinical, blood biochemical, or histological evidence of liver damage.

[Soy isoflavones and human health: breast cancer and puberty timing]. / Isoflavonas de soya y salud humana: cáncer de mama y sincronización de la pubertad.

BACKGROUND: Accumulated exposure to high levels of estrogen is associated with an increased incidence of breast cancer. Thus, factors such as early puberty, late menopause and hormone replacement therapy are considered to be risk factors, whereas early childbirth, breastfeeding and puberty at a later age are known to consistently decrease the lifetime breast cancer risk. Epidemiological studies suggest that consumption of isoflavones correlates with a lower incidence of breast cancer. Data from human intervention studies show that the effects of isoflavones on early breast cancer markers differ between pre- and post-menopausal women. The reports from experimental animals (rats and mice) on mammary tumors are variable. These results taken together with heterogeneous outcomes of human interventions, have led to a controversy surrounding the intake of isoflavones to reduce breast cancer risk. This review summarizes recent studies and analyzes factors that could explain the variability of results. In mammary tissue, from the cellular endocrine viewpoint, we analyze the effect of isoflavones on the estrogen receptor and their capacity to act as agonists or antagonists. On the issue of puberty timing, we analyze the mechanisms by which girls, but not boys, with higher prepuberal isoflavone intakes appear to enter puberty at a later age.

A new group of cosmopolitan bacteriophages induce a carrier state in the pandemic strain of Vibrio parahaemolyticus.

A clonal population of pathogenic Vibrio parahaemolyticus O3 : K6 serovar has spread in coastal waters, causing outbreaks worldwide since 1996. Bacteriophage infection is one of the main factors affecting bacterial strain concentration in the ocean. We studied the occurrence and properties of phages infecting this V. parahaemolyticus pandemic strain in coastal waters. Analysing 143 samples, phages were found in 13. All isolates clustered in a closely related group of podophages with at least 90% nucleotide sequence identity in three essential genes, despite distant geographical origins. These bacteriophages were able to multiply on the V. parahaemolyticus pandemic strain, but the impact on host concentration and subsequent growth was negligible. Infected bacteria continued producing the phage but were not lysogenized. The phage genome of prototype strain VP93 is 43 931 nucleotides and contains 337 bp direct terminal repeats at both ends. VP93 is the first non-Pseudomonas phage related to the PhiKMV-like subgroup of the T7 supergroup. The lack of a major effect on host growth suggests that these phages exert little control on the propagation of the pandemic strain in the environment. This form of phage growth can be modelled if phage-sensitive and -resistant cells that convert to each other with a high frequency are present in clonal cultures of pandemic V. parahaemolyticus.

Mating changes the subcellular distribution and the functionality of estrogen receptors in the rat oviduct.

BACKGROUND: Mating changes the mode of action of 17beta-estradiol (E2) to accelerate oviductal egg transport from a nongenomic to a genomic mode, although in both pathways estrogen receptors (ER) are required. This change was designated as intracellular path shifting (IPS). METHODS: Herein, we examined the subcellular distribution of ESR1 and ESR2 (formerly known as ER-alpha and ER-beta) in oviductal epithelial cells of rats on day 1 of cycle (C1) or pregnancy (P1) using immunoelectron microscopy for ESR1 and ESR2. The effect of mating on intraoviductal ESR1 or ESR2 signaling was then explored comparing the expression of E2-target genes c-fos, brain creatine kinase (Ckb) and calbindin 9 kDa (s100g) in rats on C1 or P1 treated with selective agonists for ESR1 (PPT) or ESR2 (DPN). The effect of ER agonists on egg transport was also evaluated on C1 or P1 rats. RESULTS: Receptor immunoreactivity was associated with the nucleus, cytoplasm and plasma membrane of the epithelial cells. Mating affected the subcellular distribution of both receptors as well as the response to E2. In C1 and P1 rats, PPT increased Ckb while both agonists increased c-fos. DPN increased Ckb and s100g only in C1 and P1 rats, respectively. PPT accelerated egg transport in both groups and DPN accelerated egg transport only in C1 rats. CONCLUSION: Estrogen receptors present a subcellular distribution compatible with E2 genomic and nongenomic signaling in the oviductal epithelial cells of C1 and P1 although IPS occurs independently of changes in the distribution of ESR1 and ESR2 in the oviductal epithelial cells. Mating affected intraoviductal ER-signaling and induced loss of functional involvement of ESR2 on E2-induced accelerated egg transport. These findings reveal a profound influence on the ER signaling pathways exerted by mating in the oviduct.

A cyclized peptide derived from alpha fetoprotein inhibits the proliferation of ER-positive canine mammary cancer cells.

The effects of estradiol (E2) and of an AFP-derived cyclized peptide (cP) on the proliferation of primary cultures of cancer cells isolated from spontaneous canine mammary tumors were studied. The cellular response to E2 and cP was related to the expression of estradiol receptor (isoforms alpha and beta). In ER-positive cells, 2 nM estradiol increased cell proliferation and the phosphorylation of ERK1/2; 2 microg/ml cP inhibited all these effects. Estradiol also increased HER2 immunoreactivity in ER-positive cells, an effect that was reverted to its basal values by cP. Estradiol stimulated in these cells the release of MMP2 and MMP9 and the shedding of HB-EGF, effects that the cP did not affect. ER-negative cells were refractory to estradiol or cP. All canine mammary tumor cells in culture responded to treatments analogously to human mammary cancer cells. Our results support the proposal of cP as a new, potentially effective therapeutic agent for the management of mammary cancer.

A cyclic peptide derived from alpha-fetoprotein inhibits the proliferative effects of the epidermal growth factor and estradiol in MCF7 cells.

A cyclic peptide derived from the active domain of alpha-fetoprotein (AFP) significantly inhibited the proliferation of MCF7 cells stimulated with the epidermal growth factor (EGF) or estradiol (E2). The action of these three agents on cell growth was independent of the presence of calf serum in the culture medium. Our results demonstrated that the cyclic peptide interfered markedly with the regulation of MAPK by activated c-erbB2. The cyclic peptide showed no effect on the E2-stimulated release of matrix metalloproteinases 2 and 9 nor on the shedding of heparin-binding EGF into the culture medium. We propose that the AFP-derived cyclic peptide represents a valuable novel antiproliferative agent for treating breast cancer.

A peptide derived from alpha-fetoprotein inhibits the proliferation induced by estradiol in mammary tumor cells in culture.

This study was aimed to obtain additional information on the activity of a cyclized 9-amino acid peptide (cP) containing the active site of alpha fetoprotein, which inhibits the estrogen-stimulated proliferation of tumor cells in culture and of xenografts in immunodeficient mice. Breast cancer cells cultured in the presence of 2 nM estradiol were exposed to cP for different periods and their proliferation, estradiol binding parameters, clustering tendency and expression of E-cadherin and p21Cip1 were analyzed by biochemical and cell biology methods. The proliferation of MCF7 cells was significantly decreased by the addition of 2 microg/ml cP to the medium. cP did not increase cell death rate nor alter the number of binding sites for estradiol nor the endogenous aromatase activity of MCF7 cells. cP also decreased the proliferation of estrogen-dependent ZR75-1 cells but had no effect on estrogen-independent MDA-MB-231 cells. An increased nuclear p21Cip1 expression detected after cP treatment suggests that cP slows MCF7 cell proliferation via this regulator. We propose that cP could represent a novel breast cancer therapeutic agent whose mechanism of action is different from that of tamoxifen or of inhibitors of aromatase.

A synthetic peptide derived from alpha-fetoprotein inhibits the estradiol-induced proliferation of mammary tumor cells in culture through the modulation of p21.

A stable cyclized 9-mer peptide (cP) containing the active site of alpha-alpha fetoprotein (alphaFP) has been shown to be effective for prevention of estrogen-stimulated tumor cell proliferation in culture or of xenographt growth in immunodeficient mice. cP does not block 17beta-estradiol (E2) binding to its receptors, but rather appears to interfere with intracellular processing of the signal that supports growth. To obtain insight on that mechanism we studied the effect of cP on the proliferation of MCF-7 cells in culture. Proliferation in the presence of 2 microM E2 is decreased up to 40% upon addition of 2 microg ml(-1) cP to the medium; the presence of cP did not increase cell death, cP reduced also the proliferation of estrogen-dependent ZR75-1 cells but had no effect on autonomous MDA-MB-231 cells, cP did not modify the number of binding sites for labeled E2 or affected cell death. We detected increased nuclear p21Cip1 immunoreactivity after cP treatment. Our results suggest that cP acts via p21Cip1 to slow the process of MCF-7 cells through the cycle.

Effect of prenatal protein malnutrition on long-term potentiation and BDNF protein expression in the rat entorhinal cortex after neocortical and hippocampal tetanization.

Reduction of the protein content from 25 to 8% casein in the diet of pregnant rats results in impaired neocortical long-term potentiation (LTP) of the offspring together with lower visuospatial memory performance. The present study was aimed to investigate whether this type of maternal malnutrition could result in modification of plastic capabilities of the entorhinal cortex (EC) in the adult progeny. Unlike normal eutrophic controls, 55-60-day-old prenatally malnourished rats were unable to develop LTP in the medial EC to tetanizing stimulation delivered to either the ipsilateral occipital cortex or the CA1 hippocampal region. Tetanizing stimulation of CA1 also failed to increase the concentration of brain-derived neurotrophic factor (BDNF) in the EC of malnourished rats. Impaired capacity of the EC of prenatally malnourished rats to develop LTP and to increase BDNF levels during adulthood may be an important factor contributing to deficits in learning performance having adult prenatally malnourished animals.

Features of natural and gonadotropin-releasing hormone antagonist-induced corpus luteum regression and effects of in vivo human chorionic gonadotropin.

CONTEXT: The natural process of luteolysis and luteal regression is induced by withdrawal of gonadotropin support. OBJECTIVE: The objectives of this study were: 1) to compare the functional changes and apoptotic features of natural human luteal regression and induced luteal regression; 2) to define the ultrastructural characteristics of the corpus luteum at the time of natural luteal regression and induced luteal regression; and 3) to examine the effect of human chorionic gonadotropin (hCG) on the steroidogenic response and apoptotic markers within the regressing corpus luteum. DESIGN: Twenty-three women with normal menstrual cycles undergoing tubal ligation donated corpus luteum at specific stages in the luteal phase. Some women received a GnRH antagonist prior to collection of corpus luteum, others received an injection of hCG with or without prior treatment with a GnRH antagonist. MAIN OUTCOME MEASURE: Main outcome measures were plasma hormone levels and analysis of excised luteal tissue for markers of apoptosis, histology, and ultrastructure. RESULTS: The progesterone and estradiol levels, corpus luteum DNA, and protein contents in induced luteal regression resembled those of natural luteal regression. hCG treatment raised progesterone and estradiol in both natural luteal regression and induced luteal regression. The increase in apoptosis detected in induced luteal regression by cytochrome c in the cytosol, activated caspase-3, and nuclear DNA fragmentation, was similar to that observed in natural luteal regression. The antiapoptotic protein Bcl-2 was significantly lower during natural luteal regression. The proapoptotic proteins Bax and Bak were at a constant level. Apoptotic and nonapoptotic death of luteal cells was observed in natural luteal regression and induced luteal regression at the ultrastructural level. hCG prevented apoptotic cell death, but not autophagy. CONCLUSION: The low number of apoptotic cells disclosed and the frequent autophagocytic suggest that multiple mechanisms are involved in cell death at luteal regression. hCG restores steroidogenic function and restrains the apoptotic process, but not autophagy.

Adult hippocampus derived soluble factors induce a neuronal-like phenotype in mesenchymal stem cells.

Bone marrow-derived mesenchymal stem cells (MSCs) are not restricted in their differentiation fate to cells of the mesenchymal lineage. They acquire a neural phenotype in vitro and in vivo after transplantation in the central nervous system. Here we investigated whether soluble factors derived from different brain regions are sufficient to induce a neuronal phenotype in MSCs. We incubated bone marrow-derived MSCs in conditioned medium (CM) derived from adult hippocampus (HCM), cortex (CoCM) or cerebellum (CeCM) and analyzed the cellular morphology and the expression of neuronal and glial markers. In contrast to muscle derived conditioned medium, which served as control, conditioned medium derived from the different brain regions induced a neuronal morphology and the expression of the neuronal markers GAP-43 and neurofilaments in MSCs. Hippocampus derived conditioned medium had the strongest activity. It was independent of NGF or BDNF; and it was restricted to the neuronal differentiation fate, since no induction of the astroglial marker GFAP was observed. The work indicates that soluble factors present in the brain are sufficient to induce a neuronal phenotype in MSCs.

Mild prenatal protein malnutrition increases alpha 2C-adrenoceptor expression in the rat cerebral cortex during postnatal life.

Mild reduction in the protein content in the diet of pregnant rats from 25 to 8% casein, calorically compensated by carbohydrates, does not alter body and brain weights of rat pups at birth, but results in significant changes of the concentration and release of cortical noradrenaline during postnatal life, together with impaired long-term potentiation and memory formation. Since some central noradrenergic receptors are critically involved in neuroplasticity, the present study evaluated, by utilizing immunohistochemical methods, the effect of mild prenatal protein malnutrition on the alpha 2C-adrenoceptor expression in the frontal and occipital cortices of 8- and 60-day-old rats. At day 8 of postnatal age, prenatally malnourished rats exhibited a three-fold increase of alpha 2C-adrenoceptor expression in both the frontal and the occipital cortices, as compared to well-nourished controls. At 60 days of age, prenatally malnourished rats showed normal expression levels scores of alpha 2C-adrenoceptor in the neocortex. Results suggest that overexpression of neocortical alpha 2C-adrenoceptors during early postnatal life, subsequent to mild prenatal protein malnutrition, could in part be responsible for neural and behavioral disturbances showing prenatally malnourished animals during the postnatal life.

Weight increase and overweight are associated with DNA oxidative damage in skeletal muscle.

BACKGROUND AND AIMS: Weight maintenance within normal standards is recommended for prevention of conditions associated with oxidative injury. To compare oxidative damage in a post mitotic tissue, between adults differing in long-term energy balance. METHODS: During hernia surgery, a sample of skeletal muscle was obtained in 17 non-obese adults. Subjects were divided into two groups according to their self-reported weight change: weight maintainers (WM) reported <4kg increase, and weight gainers (WG) reported >5kg increment. Muscle immunohistochemistry for 8-hydroxy-deoxyguanosine (8OHdG), 4-Hydroxy-2-nonenal (4HNE), and TNF-alpha, as markers of oxidative injury and inflammation, were performed. As known positive controls for oxidative injury, we included 10 elderly subjects (66-101yr). Anthropometric measures and blood samples for clinical laboratory and serum cytokines (TNF-alpha and IL-6) were obtained. RESULTS: 8OHdG was higher in WG compared with WM (149.1+/-16.2 versus 117.8+/-29.5, P=0.03), and was associated with anthropometric indicators of fat accumulation. 4HNE was similar in WG compared with WM (10.9+/-7.6 versus 9.8+/-6.3) but noticeably higher in elderly subjects (21.5+/-15.3, P=0.059). TNF-alpha protein in WG was higher compared with WM (114.0+/-41.7 versus 70.1+/-23.3, P=0.025), and was associated with weight increase. CONCLUSIONS: Moderate self-reported weight increase, and body fat accumulation, suggesting long-term positive energy balance is associated with muscle DNA oxidative injury and inflammation.

Melatonin administration impairs visuo-spatial performance and inhibits neocortical long-term potentiation in rats.

Melatonin has been shown to inhibit long-term potentiation (LTP) in hippocampal slices of rats. Since LTP may be one of the main mechanisms by which memory traces are encoded and stored in the central nervous system, it is possible that melatonin could modulate cognitive performance by interfering with the cellular and/or molecular mechanisms involved in LTP. We investigated in rats the effects of intraperitoneally-administered melatonin (0.1, 1 and 10 mg/kg), its saline-ethanol solvent, or saline alone, on the acquisition of visuo-spatial memory as well as on the ability of the cerebral cortex to develop LTP in vivo. Visuo-spatial performance was assessed daily in rats, for 10 days, in an 8-arm radial maze, 30 min after they received a single daily dose of melatonin. Visual cortex LTP was determined in sodium pentobarbital anesthetized rats (65 mg/kg i.p.), by potentiating transcallosal evoked responses with a tetanizing train (312 Hz, 500 ms duration) 30 min after administration of a single dose of melatonin. Results showed that melatonin impaired visuo-spatial performance in rats, as revealed by the greater number of errors committed and time spent to solve the task in the radial maze. Melatonin also prevented the induction of neocortical LTP. It is concluded that melatonin, at the doses utilized in this study, could alter some forms of neocortical plasticity involved in short- and long-term visuo-spatial memories in rats.

Effects of chronic copper exposure during early life in rhesus monkeys.

BACKGROUND: Whether infants regulate copper absorption and the potential effects of excess copper in early life remain poorly defined. OBJECTIVE: The objective of the study was to assess copper retention, liver copper content, and liver function in infant rhesus monkeys fed infant formula containing 6.6 mg Cu/L. DESIGN: From birth to 5 mo of age, infant rhesus monkeys were fed formula that was supplemented with copper (0.6 mg Cu/L; n = 5) or not supplemented (n = 4). In all animals, weight and crown-rump length (by anthropometry), hemoglobin, hematocrit, plasma ceruloplasmin activity, and zinc and copper concentrations were measured monthly (birth to 6 mo) and at 8 and 12 mo. When the animals were 1, 5, and 8 mo old, liver copper and metallothionein concentrations, liver histology (by light and electron microscopy), and the number of Kupffer cells were assessed, and 67Cu retention was measured. Liver function was assessed by measurement of plasma alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, and alkaline phosphatase activities and protein, albumin, bilirubin, and blood urea nitrogen concentrations. RESULTS: 67Cu retention was 19.2% and 10.9% after 1 and 5 mo of copper treatment, respectively, compared with approximately 75% in controls at age 2 mo. At age 8 mo, 67Cu retention was 22.9% in copper-treated animals and 31.5% in controls. Liver histology remained normal by light microscopy, with mild ultrastructural signs of cell damage at 5 mo. Liver copper concentration was 4711, 1139, and 498 microg/g dry tissue at 1, 5, and 8 mo, respectively, in copper-treated animals and 250 microg/g at 2 mo in controls. Measurements could not be completed in all animals. CONCLUSIONS: No clinical evidence of copper toxicity was observed. Copper absorption was down-regulated; increases in liver copper content at ages 1 and 5 mo did not result in histologic damage. Ultrastructural changes at age 5 mo could signal early cellular damage.

Nonstimulated human uncommitted mesenchymal stem cells express cell markers of mesenchymal and neural lineages.

Ex vivo cultures of human bone marrow-derived mesenchymal stem cells (MSCs) contain subsets of progenitors exhibiting dissimilar properties. One of these subsets comprises uncommitted progenitors displaying distinctive features, such as morphology, a quiescent condition, growth factor production, and restricted tissue biodistribution after transplantation. In this study, we assessed the competence of these cells to express, in the absence of differentiation stimuli, markers of mesoderm and ectodermic (neural) cell lineages. Fluorescence microscopy analysis showed a unique pattern of expression of osteogenic, chondrogenic, muscle, and neural markers. The depicted "molecular signature" of these early uncommitted progenitors, in the absence of differentiation stimuli, is consistent with their multipotentiality and plasticity as suggested by several in vitro and in vivo studies.

Ultrastructural and biochemical evidence for the presence of mature steroidogenic acute regulatory protein (StAR) in the cytoplasm of human luteal cells.

The distribution of the steroidogenic acute regulatory protein (StAR) inside thecal and granulosa-lutein cells of human corpus luteum (CL) was assessed by immunoelectron microscopy. We found greater levels of StAR immunolabeling in steroidogenic cells from early- and mid-than in late luteal phase CL and lower levels in cells from women treated with a GnRH antagonist in the mid-luteal phase. Immunoelectron microscopy revealed significant levels of StAR antigen in the mitochondria and in the cytoplasm of luteal cells. The 30 kDa mature StAR protein was present in both mitochondria and cytosol (post-mitochondrial) fractions from homogenates of CL at different ages, whereas cytochrome c and mitochondrial HSP70 were detected only in the mitochondrial fraction. Therefore, we hypothesized that either appreciable processing of StAR 37 kDa pre-protein occurs outside the mitochondria, or mature StAR protein is selectively released into the cytoplasm after mitochondrial processing. The presence of mature StAR in the cytoplasm is consonant with the notion that StAR acts on the outer mitochondrial membrane to effect sterol import, and that StAR may interact with other cytoplasmic proteins involved in cholesterol metabolism, including hormone sensitive lipase.

The steroidogenic response and corpus luteum expression of the steroidogenic acute regulatory protein after human chorionic gonadotropin administration at different times in the human luteal phase.

This study was designed 1) to assess corpus luteum (CL) steroidogenesis in response to exogenous human chorionic gonadotropin (hCG) at different times during the luteal phase, 2) to examine the effect of hCG on steroidogenic acute regulatory protein (StAR) expression within the CL, 3) to correlate StAR expression and luteal steroidogenic responses to hCG, and 4) to determine whether endogenous LH regulates ovarian steroidogenesis in the early luteal phase. Blood was collected before and after hCG treatment for steroid and hCGbeta determinations. CL were obtained at the time of surgery to assess StAR gene and protein expression. During the early luteal phase various women received the GnRH antagonist for 24-48 h; some of them also received hCG 24 h after the GnRH antagonist. A slight steroidogenic response to hCG was observed in early luteal phase; 17alpha-hydroxyprogesterone, but not progesterone (P4), levels were significantly increased 8 h post-hCG, indicating a differential response by the granulosa and theca-lutein cells. The 1.6- and 4.4-kb StAR transcripts and the 37-kDa preprotein and 30-kDa mature StAR protein did not change post-hCG administration in early luteal phase CL. In contrast, the StAR 4.4- and 1.6-kb transcripts diminished significantly (P < 0.05) after the antagonist treatment. Immunohistochemical staining for StAR protein was weak, particularly in granulosa-lutein cells. Treatment with hCG restored StAR mRNA and protein and plasma P4 levels within 24 h in antagonist-treated women. hCG stimulated the highest plasma concentrations of P4 and estradiol in the midluteal phase, indicating its greatest steroidogenic capacity. Midluteal tissue StAR gene and protein expression increased by 1.6- and 1.4-fold after 24 h of hCG treatment, respectively. Administration of hCG resulted in the greatest increment in plasma P4 (4-fold) and 17alpha-hydroxyprogesterone (3-fold) levels over baseline in the late luteal phase. This was associated with an increase in StAR mRNA (3.5-fold) and protein (1.8-fold). Collectively, these data indicate that 1) the hCG-stimulated steroidogenic response is dependent on the age of the CL; 2) the early luteal phase CL is relatively insensitive to exogenous hCG in the presence of normal pituitary gonadotropin support, but becomes responsive when the latter is withdrawn; 3) the hCG-stimulated steroidogenic response in the mid- and late luteal phase is correlated with increased StAR mRNA and protein abundance; and 4) there are differential responses of small and large luteal cells to hCG stimulation that depend upon the age of the CL.

Marrow-derived mesenchymal stem cells: role in epithelial tumor cell determination.

Marrow stroma represents an advantageous environment for development of micrometastatic cells. Within the cellular structure of marrow stroma, mesenchymal stem cells (MSC) have been postulated as an interacting target for disseminated cancer cells. The studies reported here were performed to gain more information on the interaction of the human breast cancer cell line MCF-7 with human bone marrow-derived MSC cells and to investigate whether this interaction affects tumor cell properties. The results showed that after co-culture with MSC, changes were detected in the morphology, proliferative capacity and aggregation pattern of MCF-7 cells, but these parameters were not affected after the co-culture of MSC cells with a non-tumorigenic breast epithelial cell line, MCF-10. Since the indirect culture of MCF-7 with MSC or its products also resulted in functional changes in the tumor cells, we evaluated whether these effects could be attributed to growth factors produced by MSC cells. It was found that VEGF and IL-6 mimic the effects produced by MSC or its products on the proliferation and aggregation properties of MCF-7, cells, respectively. Thus, it seems that after entry of disseminated tumor cells into the marrow space, their proliferative and morphogenetic organization patterns are modified after interaction with distinct stromal cells and/or with specific signals from the marrow microenvironment.