Role of fibroblast growth factor 8 in growth and progression of hormonal cancer

Hormonal cancers such as breast and prostate cancer arise from steroid hormone-regulated tissues. In addition to breast and prostate cancer hormonal regulation has also a role in endometrial, ovarian, testis and thyroid carcinomas. The effects of estrogens, androgens and progestagens on tumor growth are largely mediated by paracrine and autocrine target molecules which include growth factors and growth factor receptors. During cancer progression the hormonal growth regulation is often lost or overcome by an inappropriate activation of growth factor signaling cascades. One of the growth factors which have been associated with the regulation of growth and progression of hormonal cancer is fibroblast growth factor 8 (FGF8) which has also been recognized as an oncogene. FGF8 is widely expressed during embryonic development. It has been shown to mediate embryonic epithelial-mesenchymal transition and to have a crucial role in gastrulation and early organization and differentiation of midbrain/hindbrain, pharyngeal, cardiac, urogenital and limb structures. During adulthood FGF8 expression is much more restricted but in hormonal cancers it becomes frequently activated. High level of FGF8 expression in tumors is associated with a poor prognosis at least in prostate cancer. In experimental models FGF8 induces and facilitates prostate tumorigenesis and increases growth and angiogenesis of tumors. Several lines of evidence for autocrine and paracrine loops in the growth regulation of breast, prostate and ovarian cancer by FGF8 have been suggested.     

Incorporation of cholesterol into serum high and low density lipoproteins

Excess cholesterol (CHL) was incorporated into serum lipoproteins by incubation with Celite^®-dispersed CHL or CHL crystals. The initial rates of uptake were 15 and 7 mol CHL/mol lipoprotein × h^? for low (LDL) and high (HDL) density lipoprotein, respectively. Saturation values were obtained after 48 h and were 90 and 65 mol CHL/mol LDL, and 42 and 32 mol/mol HDL using CHL on Celite and CHL cyrstals, respectively. Characterization of the lipo-proteins showed a small change in electrophoretic mobility and an increase in molecular masses, especially after incubation with CHL on Celite. Spectroscopic methods showed only minor effects on the protein moieties.     

Polyamine deprivation causes major chromosome aberrations in a polyamine-dependent Chinese hamster ovary cell line

This paper describes the effects of polyamine deprivation on chromosomes of a polyamine-dependent Chinese hamster ovary cell line which grows continuously in serum-free medium. After 6 days' polyamine deprivation the number of mitoses decreased drastically and most of them showed major chromosome aberrations. There were several gaps and breaks in many chromosomes, some cells exhibiting extensive chromosome fragmentation. Elongation of chromosomes, indicative for unpacking of the chromosome fibres, were also seen. The time course of Harlequin staining of the chromosomes revealed prolongation of the cell cycle in the polyamine-starved cells. The mean number of sister chromatid exchanges per cell was a little higher in the polyamine-starved than in the control cells. The difference is statistically significant, but it has to be taken with some caution, because the experiments could not be carried out under strictly comparable conditions.     

The role of local adaptation in the relationship between an endangered root hemiparasite Euphrasia rostkoviana, and its host, Agrostis capillaris

We experimentally studied the role of local adaptation and the co-evolutionary relationship between an annual, endangered root hemiparasite Euphrasia rostkoviana and its main host Agrostis capillaris. According to our hypothesis, the existence of local adaptation in hemiparasites should be observable in better hemiparasite performance when attached to A. capillaris hosts originating From Euphrasia populations. After one month of growth, the height and the number of leaves of hemiparasites were not affected by the origin of their hosts. The differences in growth were due to between population effects. The situation remained constant after three months. Hemiparasite biomass was not affected by the origin of the hosts. The percentage of hemiparasites surviving after one. two and three months was not affected by the origin of the hosts although there was a weak tendency towards better survival of hemiparasites with familiar hosts than with unfamiliar hosts. All variables used to measure hemiparasite performance during its complete life-cycle gave only limited support for the local adaptation hypothesis. Nevertheless, the familiar hosts suffered less from parasitism as indicated by their higher biomass after the experiment. This suggests that there may be some interactions between hemiparasites and their hosts based on their spatial population structure and common history as competitors.     

Activin-A, but not inhibin, regulates 17β-hydroxysteroid dehydrogenase type 1 activity and expression in cultured rat granulosa cells

17β-Hydroxysteroid dehydrogenase type 1 (17HSD type 1) catalyzes the reduction of estrone (E₁) to biologically more active estradiol (E₂). In the present study, the effect of activin, inhibin, and follistatin on 17HSD activity and 17HSD type 1 expression in cultured, unluteinized rat granulosa cells was examined. Furthermore, the effects of these hormones on 17HSD type 1 expression were compared with the expression of P450 aromatase (P450arom). Rat granulosa cells were pre-incubated in serum-free media for 3 days, followed by a 2-day treatment with activin, inhibin, follistatin and 8-Br-cAMP. Activin in increasing concentrations appeared to effect a dose-dependent increase in 17HSD activity. In addition, increasing concentrations of activin also increased 17HSD type 1 mRNA expression. Addition of 8-Br-cAMP at concentrations of 0.25 and 1.5 mmol/l together with activin significantly augmented the stimulatory effects of activin alone in the cultured cells. Neither inhibin, nor follistatin, either alone or in combination with 8-Br-cAMP, had any notable effects on 17HSD activity and 17HSD type 1 expression. Preincubation of activin with increasing concentrations of follistatin significantly diminished the stimulatory effect of activin. In the presence of follistatin, activin did not significantly increase the 8-Br-cAMP-induced 17HSD activity and 17HSD type 1 expression. The culturing of granulosa cells in the presence or the absence of inhibin or follistatin with or without 8-Br-cAMP did not alter the effect of these peptides on P450arom expression in rat granulosa cells as judged by Northern blot analysis of total RNA. However, cAMP-induced P450arom expression was enhanced by activin treatment, except when follistatin was present. This is in line with the suggested role of follistatin as an activin-binding protein, which limits the bioavailability of activin to its membrane receptors. Thus, the results support the notion of a paracrine/autocrine role of activin in follicular steroidogenesis of growing follicles.     

Constructed deletions in lumen-exposed regions of the D1 protein in the cyanobacterium Synechocystis 6803: Effects on D1 insertion and accumulation in the thylakoid membrane, and on Photosystem II assembly

Modified forms of the D1 protein with deletions in lumen-exposed regions, were constructed in the cyanobacterium Synechocystis 6803 using site-directed mutagenesis. Integration and stability of the mutated D1 proteins in the thylakoid membrane were studied by immunoblot and pulse-chase analyses. It was found that in (N325-E333), the D1 protein with a deletion in the C-terminal tail, could insert in the thylakoids to normal amounts but its stability in the membrane was dramatically reduced. Insertion of D1 in (V58-D61) or (D103-G109);G110R, with deletions in the A-B loop, was severely obstructed, For (P350-T354), with a deletion in the processed region of the C-terminus of D1, no phenotypic effects were observed. The effects of failed D1 insertion or accumulation on Photosystem II assembly was monitored by immunoblot analysis. The conclusions from these experiments are that the extrinsic 33 kDa protein, CP43, and the subunit of cytochrome b559 accumulate in the thylakoid membrane independently of the D1 protein, and that accumulation of the D2 protein and CP47 requires insertion but not necessarily accumulation of the D1 protein.Abbreviations PSI II Photosystem II - PCR Polymerase Chain reaction Present address: Université Joseph Fourier, Sciences Technologie Médecine, BP 53, 38041 Grenoble Cedex 9, France     

Na entry and Na-K pump activity in murine,hamster, and human cells - effect of monensin,serum, platelet extract,and viral transformation

The relationship between Na entry and the activity of the Na-K pump has been investigated in a variety of cell types by testing the effect of the Naionophore monensin, mitogenic stimulation with serum and oncogenic transformation by SV₄₀ and polyoma virus. We found that addition of monensin increases intracellular Na in quiescent cultures of murine, hamster, and human cells. In each case, the rise in intracellular Na by monensin is associated with an increase in the activity of the Na-K pump, which was measured as ouabain-inhibitable ⁸⁶Rb uptake. The addition of serum to quiescent cultures stimulates ⁸⁶Rb uptake in all cell types studied. Serum alone causes an increase in intracellular potassium with no consistent change in intracellular Na. In the presence of the Na-K pump inhibitor ouabain, serum causes a marked increase in intracellular Na, with little change in intracellular K. This pattern is interpreted as indicating that the primary effect of serum is to increase Na entry into the cells. A low concentration of monensin (0.2 μg/ml) mimics the effect of serum on ion fluxes and content, which supports the conclusion that serum and monensin stimulate ⁸⁶Rb uptake in the same manner, namely by increasing Na entry into the cells. In addition, a partially purified platelet extract stimulates Na entry and ⁸⁶Rb uptake in quiescent 3T3 cells. Finally 3T3 cells transformed by SV₄₀ or polyoma virus exhibit a higher rate of Na entry and of Na-K pump activity than their untransformed 3T3 counterparts. All these results indicate that the rate of Na entry plays an important role in the regulation of the activity of the Na-K pump and that an increase in Na and K movements is a rapid response elicited by serum in a variety of cell types.