PubMed Health⌕ Search

Biomedical subjects

B Nicolas

Publications and source records attributed to B Nicolas.

31 records · Page 2Linked to original sources
PubMed1995

Androgens inhibit the proliferation of a variant of the human prostate cancer cell line LNCaP.

UNLABELLED: The paradoxical androgen response of R2, a subline of the human prostate cancer cell line LNCaP, is described here. Two androgens (DHT and R1881) decreased, in a dose-dependent manner, R2 cell proliferation and [3H]thymidine incorporation. These ligand and cell specific effects were accompanied by an increase in the metabolism of the vital dye MTT and in cell protein content. Both androgens increased the doubling time and the percentage of G0-G1 cells. No evidence of androgen-induced apoptosis was found. Cloning allowed the selection of two cell populations on the basis of the response to 10 nM of R1881. Long term culture of uncloned R2 cells with R1881 modified reversibly the pattern of androgen response. R2 was compared to the androgen-stimulated LNCaP-FGC subline to investigate the causes of their different androgen responsiveness. The androgen receptor (number, affinity for hormones and antihormones, sedimentation constant and molecular weight) and androgen receptor genes (exon size and exon 8 sequence) were found to be identical in the two sublines. EGF stimulated LNCaP-FGC but not R2. Both cells were slightly stimulated by basic FGF but were insensitive to IGF-I and TGF beta 1. IN CONCLUSION: (1) androgens inhibit the proliferation of R2 cells possibly by introducing a G0-G1 block; (2) this inhibition is incomplete because, at least in part, the R2 cell population is heterogeneous; (3) chronic androgen treatment induces reversible cell adaptation; and (4) there is no evidence that the loss of the classical stimulatory effect of androgen on cell proliferation and the gain of inhibitory effect are due to androgen receptor alteration or to a specific action of one of the four growth factors tested.

Amino Acid Sequence↗
PubMed1995

The reflex sympathetic dystrophy syndrome in patients who have had a spinal cord injury.

Patients suffering from a spinal cord injury often present with a pain syndrome. Although the reflex sympathetic syndrome is a common diagnosis in some forms of neurological disease such as patients with a stroke, it is less frequent in those with a spinal lesion. The authors report eight patients with reflex sympathetic dystrophy who had a spinal cord injury. The diagnosis and treatment are discussed along with a review of literature.

Adult↗
PubMed1995

Assessment of immunotoxic effects in humans.

The immunotoxic effects of chemicals are varied and markedly different depending on the underlying pathogenesis, namely, direct immunotoxicity (including immunosuppression, immunodepression, and immunostimulation), hypersensitivity, and autoimmunity. A large number of immunological endpoints and functional assays have been proposed for use as biomarkers of immunotoxicity, but they often lack sensitivity or are poorly standardized, so that their relevance in assessing immunotoxic effects in humans is at best ill established. Examining sentinel immunopathological events in individuals with a defined history of chemical exposure is another approach, presumably more cost-effective at the present time. A multicenter collaboration is mandated, however, because these events are rare. We expect that progress in new technologies, e.g., molecular biology, will provide the sensitive and reliable biomarkers of immunotoxicity that are currently lacking.

Autoimmune Diseases↗
PubMed1994

[Urination disorders in multiple sclerosis: value of urodynamic assessment].

Urinary troubles are common in patients with multiple sclerosis. The management of these troubles requires an accurate analysis. Urodynamic assessment was preformed in 117 patients with urinary symptoms positively diagnosed as suffering from multiple sclerosis. Urinary symptoms are not always correlated to urodynamic patterns. We have studied the correlation between urinary symptoms and urodynamic findings. Urodynamic results are similar to most of previous series: detrusor hyperreflexia is the most frequent abnormality, detrusor sphincter dyssynergia is diagnosed in 50% of the patients. There is some correlations with symptoms, but there are insufficient for an accurate diagnosis. Postvoid residue for urinary tracts infectious diseases, and sphincter incompetence for urinary incontinence are the main risk factors.

Adult↗
PubMed1994

[Heterotopic ossification and vascular compression].

Heterotopic ossification is common in patients with spinal cord or brain injury. Whereas the articular complications of heterotopic ossification have been well documented, the vascular complications are less well known. We report three cases with vascular compression and discuss the diagnosis and treatment in the light of a review of the literature.

Adult↗
PubMed1993

Interference between estradiol and L-triiodothyronine in the control of the proliferation of a pituitary tumor cell line.

We showed that the proliferation of F4Z2 cells, established from a rat pituitary tumor, was stimulated by L-triiodothyronine (LT3) in the presence of 3 or 0.1% charcoal treated-fetal calf serum (CT-FCS), and by estradiol (E2) in the presence of 3% CT-FCS only (Cancer Res., 50, 1990, 3786). Here we report on the consequences of the simultaneous addition of these hormones. In the presence of 0.1% CT-FCS, E2, and with a lower potency, estrone and estriol inhibited dose-dependently stimulation by LT3. The results were more complex with 3% CT-FCS: the LT3 effect was blunted by E2 > 0.1 nM (and vice versa) and the hormone effects were additive at lower concentrations. E2, at concentrations antagonistic to the effects of LT3, decreased LT3 binding and LT3 receptor mRNA without modifying the effect of LT3 on these mRNAs. In addition, E2 blocked both the LT3-induced increases of insulin-like growth factor-I (IGF-I) secretion and IGF-I mRNA concentration, and the LT3-induced decrease of IGF-binding proteins in conditioned culture medium. We propose that E2 prevents LT3 stimulation of F4Z2 cell proliferation by blunting the LT3-induced accumulation of unbound IGF-I in the culture medium.

Animals↗
PubMed1992

Possible involvement of transforming growth factor-beta in the inhibition of rat pituitary tumor growth by estradiol.

We have shown that growth of F4Z2 cells and F4Z2 tumors was stimulated by estradiol, that of MtTF4 and F4P tumors was inhibited and that of F4P cells remained insensitive. In the present work we explore the possible role of transforming growth factor-beta (TGF-beta) as a mediator of estradiol action in these pituitary tumors and cell lines. In vivo, estradiol treatment increased the concentration of TGF-beta 1 mRNAs in tumors whose growth was inhibited by estradiol (MtTF4 and F4P) but not in tumors whose growth was stimulated (F4Z2). F4Z2 and F4P cell lines also contained TGF-beta 1 transcripts. These cells and tumors differed by two points: the level of TGF-beta 1 transcript was higher in F4Z2 than in F4P cells while the opposite situation was observed in vivo and the concentration of TGF-beta 1 mRNA in cultured cells was insensitive to estradiol (1 or 100 x 10(-9) M). Moreover, the secretion of TGF-beta like activity assayed by two different methods was estradiol insensitive and the growth of both cell lines was dose-dependently inhibited by TGF-beta 1 (ED50:2 x 10(-11) M). Since estradiol increases TGF-beta 1 mRNA in the tumors MtTF4 and F4P whose growth is inhibited by estradiol and that TGF-beta 1 inhibits the proliferation of F4P cells it is proposed as a working hypothesis that TGF-beta 1 is one of the mediators of the inhibitory effect of estradiol in pituitary tumors. No data favor the hypothesis that estradiol stimulates pituitary tumor proliferation by decreasing TGF-beta production.

Animals↗
PubMed1992

Antiestrogens prevent the stimulatory effects of L-triiodothyronine on cell proliferation.

This paper studies the modulatory effects of two antiestrogens, the steroid ICI 164 384 and the nonsteroidal compound 4-hydroxytamoxifen (4-OH-tam), on the proliferation of L-T3-stimulated cell lines. Three cell lines known to be stimulated by thyroid hormones and to contain estrogen receptors but to have a different estradiol sensitivity to estradiol were used; F4Z2 and MCF-7 cells were stimulated, whereas GH3 cells were insensitive. Cells were counted 6-7 days after hormones and antihormones were added to the culture medium, separately or in association (a fixed hormone concentration and increasing antihormone concentrations and vice versa). In F4Z2 and MCF-7 cells, antiestrogens prevented noncompetitively the stimulatory effect of L-T3 and, as expected, competitively the stimulatory effect of estradiol. In GH3 cells, antiestrogens had proper inhibitory effects, but they did not prevent significantly the proliferative effect of L-T3. To investigate the mechanisms of the modulatory effects in F4Z2 cells we examined the consequences of antiestrogens on thyroid hormone receptors (nuclear binding of L-T3 and mRNAs of thyroid hormone receptors, i.e. c-erbA alpha and -beta) and insulin-like growth factor-I (IGF-I; secretion and mRNAs). Antiestrogens neither competed with L-[125I]T3 nor reproducibly decreased the number and affinity of thyroid hormone-binding sites. While 4-OH-tam frequently decreased the amount of c-erbA beta transcripts, ICI 164 384 did not alter the distribution of alpha and beta cDNA transcripts. Further, neither antiestrogen prevented the increases in IGF-I accumulation in conditioned medium and IGF-I mRNA concentrations induced by L-T3 (0.1 nM). In conclusion, 1) antiestrogens are potent noncompetitive inhibitors of the action of L-T3 on the proliferation of cells whose growth is responsive to estradiol (F4Z2 and MCF-7), but not of the action on a cell line whose growth is insensitive to estradiol (GH3). 2) The loss of L-T3 sensitivity is not due to a loss of thyroid receptors or a decrease in IGF-I production. 3) In addition to estrogen receptors, factors involved in the estradiol control of cell proliferation appear to be required for the antiestrogen inhibition of L-T3 action.

Breast Neoplasms↗
PubMed1991

Multihormonal control of cell proliferation: opposite effects of two stimulators (17 beta-estradiol and L-triiodothyronine) and one inhibitor (dexamethasone) on F4Z2 pituitary tumor cells.

From the MtTF4 tumor of rat pituitary origin we established the F4Z2 cell line whose growth is stimulated by 17 beta-estradiol (E2). Taking E2 actions as references we investigated actions of other effectors on the proliferation, protein, and insulin growth factor-I (IGF-I) secretions of F4F2 cells. Dexamethasone (Dex) and L-T3 were chosen because they have also intracellular receptors and they act in pituitary cells. Cells were cultured in 96-well plates in RPMI 1640 medium supplemented either with charcoal-treated fetal calf serum (CT-FCS) or with BSA and transferrin. Hormones were added at the time of seeding and cells were counted 2-10 days later without renewing the culture medium. The accumulation of immunoreactive IGF-I in conditioned medium was used as an index of IGF-I secretion. For studies on protein secretion, cells were incubated for 24 h with [35S]methionine and labeled proteins were separated by polyacrylamide gel electrophoresis. We found that: 1) L-T3, like E2, stimulated in a dose-dependent and specific manner the proliferation of F4Z2 cells cultured in the presence of 5% CT-FCS; EC50 was: 1 X 10(-11) M and 0.2 X 10(-11) M for L-T3 and E2, respectively. In contrast, L-T3 but not E2 remained active in serum-free medium; 2) Dex was a strong inhibitor of cell proliferation in serum-free medium and in medium supplemented with 5% CT-FCS (EC50: 5 X 10(-9) M). The antiglucocorticoid RU 38 486 prevented this inhibitory effect; 3) when a stimulator (E2 or L-T3) was simultaneously incubated with the inhibitor (Dex) the number of cells depended on the ratio of hormone concentrations. When there was no large excess of one effector this number was intermediary between those counted in the presence of each hormone separately and L-T3 was more potent than E2 in preventing Dex inhibition; 4) Dex, E2, and L-T3 modified the electrophoretic patterns of secreted proteins but there was no evidence for a correlation between these modifications and the inhibition or the stimulation of cell proliferation, and 5) the accumulation of immunoreactive IGF-I was insensitive to E2, increased by L-T3, and markedly decreased by Dex. L-T3 but not E2 prevented the effect of Dex.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Inhibition of growth and induction of apoptosis by androgens of a variant of LNCaP cell line.

Here are described the effects of androgens, and other molecules known to bind to androgen receptors (AR), on MOP cells established from the human prostate cancer cell line LNCaP. MOP cells contained AR: 100000 binding sites/cell, K(D) for 5alpha dihydrotestosterone (DHT) 0.5 nM, size 110 kDa. The AR gene has the same repetition polymorphism in exon 1 and the T876A mutation in exon 8 as LNCaP. The proliferation of MOP cells in culture was repressed by the synthetic androgen 17beta-hydroxy-17-methyl-estra-4,9,11-trien-3-one (R 1881), the antiandrogen cyproterone acetate (CYPA), estradiol (E2), progesterone and the synthetic progestin promegestone: 17,21 dimethyl-19 nor-4,9 pregnandiene-3,20 dione (R 5020). The number of cells recovered after 7 days decreased to approximately 40% of controls. ED(70)s ranged between 50 pM for R 1881 to 50 nM for E2 and CYPA. Treatment with R 1881 decreased [3H]thymidine incorporation into DNA and increased dramatically the doubling time. R 1881, CYPA and E2 blocked the cell cycle between G1 and S phases and they induced apototosis as demonstrated by the increase of blebs on the plasma membrane, nuclear fragmentation, TdT-mediated dUTP nick end-labeling (TUNEL)-positive cells and internucleosomal DNA breaks. In athymic nude mice, testosterone enanthate prevented the growth of MOP tumors and, when tumors did develop, brought about regression. However, the tumors did not regress completely and finally escaped treatment. In conclusion, a variant of the LNCaP cell line has been established. With these cells it was possible to confirm that androgens paradoxically repress the growth of some prostate cancer cells both in culture and in vivo. In addition it is demonstrated in culture but not in vivo, for the first time to the authors' knowledge, that a synthetic androgen is able to induce apoptosis of cells established from human prostate carcinoma.

Androgens↗