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F Labrie

Publications and source records attributed to F Labrie.

At least 109 records · Page 6Linked to original sources
PubMed1997

Cloning, chromosomal localization, and functional analysis of the murine estrogen receptor beta.

Estrogen receptor beta (ER beta) is a novel steroid receptor that is expressed in rat prostate and ovary. We have cloned the mouse homolog of ER beta and mapped the gene, designated Estrb, to the central region of chromosome 12. The cDNA encodes a protein of 485 amino acids that shares, respectively, 97% and 60% identity with the DNA- and ligand-binding domains of mouse (m) ER alpha. Mouse ER beta bind to an inverted repeat spaced by three nucleotides in a gel mobility shift assay and transactivates promoters containing synthetic or natural estrogen response elements in an estradiol (E2)-dependent manner. Scatchard analysis indicates that mER beta has slightly lower affinity for E2 [dissociation constant (Kd) = 0.5 nM] when compared with mER alpha (Kd = 0.2 nM). Antiestrogens, including 4-hydroxytamoxifen (OHT), ICI 182,780, and a novel compound, EM-800, inhibit E2-dependent transactivation efficiently. However, while OHT displays partial agonistic activity with ER alpha on a basal promoter linked to estrogen response elements in Cos-1 cells, this effect is not observed with mER beta. Cotransfection of mER beta and H-RasV12 causes enhanced activation in the presence of E2. Mutagenesis of a serine residue (position 60), located within a mitogen-activated protein kinase consensus phosphorylation site abolishes the stimulatory effect of Ras, suggesting that the activity of mER beta is also regulated by the mitogen-activated protein kinase pathway. Surprisingly, the coactivator SRC-1 up-regulates mER beta transactivation both in the absence and presence of E2, and in vitro interaction between SRC-1 and the ER beta ligand-binding domain is enhanced by E2. Moreover, the ligand-independent stimulatory effect of SRC-1 on ER beta transcriptional activity is abolished by ICI 182,780, but not by OHT. Our results demonstrate that while ER beta shares many of the functional characteristics of ER alpha, the molecular mechanisms regulating the transcriptional activity of mER beta may be distinct from those of ER alpha.

Amino Acid Sequence↗
PubMed1996

Molecular cloning of human type 3 3 alpha-hydroxysteroid dehydrogenase that differs from 20 alpha-hydroxysteroid dehydrogenase by seven amino acids.

We have isolated, by screening a lambda gt11 human prostatic cDNA library, a cDNA clone that shows after transfection into transformed human embryonal kidney (293) cells high 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) activity that catalyzes efficiently the transformation of dihydrotestosterone to 5 alpha-androstane-3 alpha, 17 beta-diol. Chronologically, we name this enzyme type 3 3 alpha-HSD (3 alpha-HSD3). Surprisingly, human 3 alpha-HSD3 shares much higher amino acids sequence identity with human 20 alpha-HSD (97.8%) than with human type 1 and type 2 3 alpha-HSD (81.1 and 85.7% identity, respectively). DNA analysis predicts a protein of 323 amino acids with a molecular mass of 36,844. Alignment of the amino acid sequence of 3 alpha-HSD3 with other related 3 alpha- and 20 alpha-HSDs indicates that 3 alpha-HSD3 shares 68.1, 78.3, and 67.4% identity with rat 3 alpha-HSD and rabbit and rat 20 alpha-HSD, respectively. 3 alpha-HSD3 belongs to the aldo-keto reductase family and like almost all the members of this family preferred NADPH as cofactor.

20-Hydroxysteroid Dehydrogenases↗
PubMed1996

Growth-independent induction of spermidine transport by IL-4 and IL-13 in ZR-75-1 human breast cancer cells.

Polyamine transport is strongly induced by insulin and estradiol (E2) in ZR-75-1 human breast cancer cells. Because signal transduction mechanisms of insulin and interleukin-4 (IL-4) partly overlap, we have compared the ability of these agents as well as that of interleukin-13 (IL-13), a cytokine that often mimics IL-4, to modulate spermidine transport in these cells. In the presence of E2, insulin increased DNA content and the rate of [3H]spermidine uptake by 2.1- and 3.7-fold, respectively, after an 8-day incubation, whereas the sole addition of IL-4 caused a quantitatively similar induction of [3H]spermidine uptake while leaving cell growth unaffected. No comparable induction of spermidine transport was observed with interleukins-1 alpha and -6, and the effect of IL-4 was not additive to that elicited by insulin plus E2. IL-4 and IL-13 stimulated [3H]spermidine uptake to a comparable extent, with half-maximal effects observed at 80 and 400 pg/ml, respectively. Interferon-gamma inhibited IL-4- and IL-13-dependent spermidine uptake to a much greater extent than basal or insulin-induced transport of the polyamine. IL-4 and IL-13 increased the Vmax and K(m) of [3H]spermidine uptake by about 4- and 2.5-fold, respectively. Na(+)-dependent amino acid uptake was increased by insulin but not by IL-4 or IL-13, indicating that the cytokines do not induce a general increase in membrane transport activity. IL-4 and IL-13 did not interfere with feedback inhibition of polyamine uptake, and only modestly decreased polyamine content after prolonged incubation, suggesting that these cytokines stimulate spermidine uptake by increasing total transport capacity rather than by repressing and endogenous inhibitor.

Biological Transport↗
PubMed1996

Interleukin-4 and interleukin-13 inhibit estrogen-induced breast cancer cell proliferation and stimulate GCDFP-15 expression in human breast cancer cells.

Human breast carcinomas are frequently infiltrated by inflammatory cells secreting several cytokines which may regulate the activity of both immune cells and neoplastic cells. The present study was designed to examine the potential action of interleukin-4 (IL-4) and interleukin-13 (IL-13) in human breast cancer cells. Exposure of ZR-75-1 breast cancer cells to IL-4 or IL-13 for 10 days decreased the amplitude of the mitogenic action of 17 beta-estradiol by 75% and 55%, respectively, while these cytokines failed to change basal cell proliferation. These cytokines also exerted a similar action in T-47D cells. Exposure to IL-4 or IL-13 markedly increased gross cystic disease fluid protein-15 (GCDFP-15) release in both ZR-75-1 and T-47D cells. The half-maximal stimulatory effects of IL-4 and IL-13 on GCDFP-15 secretion were exerted at respective values of 16 +/- 3 pM and 91 +/- 8 pM in T-47D cells incubated for a period of 10 days. The effect of IL-13 was not additive to that elicited by IL-4, whereas the stimulation of GCDFP-15 release by these interleukins were additive to that exerted by maximally effective concentrations of the androgen dihydrotestosterone and the synthetic glucocorticoid dexamethasone. Furthermore, exposure of ZR-75-1 cells of IL-4 and IL-13 increased GCDFP-15 mRNA levels by 5.5- and 6.0-fold, respectively. The present results demonstrate that IL-4 and IL-13 may decrease estrogen-induced breast cancer cell proliferation and induce the expression of a breast cancer marker, thus strongly suggesting that breast cancer cells are targets of both IL-4 and IL-13 action.

Apolipoproteins↗
PubMed1996

Heterogeneity of rat type I 5 alpha-reductase cDNA: cloning, expression and regulation by pituitary implants and dihydrotestosterone.

Primer extension analysis reveals the presence of different forms of mRNA species for rat type I 5 alpha-reductase. Using a 5 alpha-reductase cDNA probe to screen the rat liver lambda gt11 cDNA library, we isolated cDNA clones that have 4 additional amino acids in the NH2-terminal region as compared with the previously reported sequence for rat type I 5 alpha-reductase. These four additional amino acids elongate the rat type I 5 alpha-reductase amino acid sequence to 259 amino acids, the same number as in human type I 5 alpha-reductase, with which it shares 60% identity. Expression of the long and short rat type I 5 alpha-reductase by transfection in human adrenal adenocarcinoma cells, SW-13 cells, indicated that the long cDNA encoded a protein with a higher affinity for the substrate than the short cDNA. To determine the effect of pituitary hormones and dihydrotestosterone (DHT), the mRNA levels in the livers of rats treated with pituitary implants, hypophysectomized, castrated, and castrated coupled with DHT treatment were quantified by dot-blot hybridization assay using rat type I 5 alpha-reductase cDNA as probes. The results demonstrated that rat type I 5 alpha-reductase mRNA is stimulated by pituitary hormones and castration but is decreased by DHT and hypophysectomy.

Amino Acid Sequence↗
PubMed1996

Androgen receptor modulation in benign human prostatic tissue and prostatic adenocarcinoma during neoadjuvant endocrine combination therapy.

Modulation of androgen receptor (AR) expression during neoadjuvant endocrine therapy in human prostates of patients with localized prostate cancer was investigated by immunohistochemistry. In 8 of 15 untreated prostatectomy specimens, the majority of prostatic glandular cells displayed nuclear immunostaining for AR, whereas only 1 of 26 pretreated cases displayed a similar glandular AR expression. Expression of AR in the prostatic stromal compartment of nontreated cases proved to be quite heterogeneous, since 4 of the 15 (27%) examined specimens did not show stromal AR expression. After preoperative neoadjuvant therapy, this value was 68%, although this difference did not reach statistical significance. Prostatectomy specimens of the treated patients contained carcinomas with a higher Gleason score than those of untreated patients. AR expression in carcinomas of treated patients was diminished (P= 0.05), which may be attributed to their relatively lower differentiation grade. The data strongly suggest that neoadjuvant hormone therapy reduces AR expression by nonneoplastic prostatic glandular cells and carcinoma cells by a selective, but incomplete, elimination of AR-positive cells.

Adenocarcinoma↗
PubMed1996

Large Shionogi tumors lose their responsiveness to flutamide treatment.

Cancer of the prostate is the most frequent cancer and the second leading cause of cancer death in men in North America. The growth of Shionogi carcinoma-115 (SC-115) cells is highly sensitive to androgens, and this cell line is a well known experimental model of prostate cancer. The transplantable Shionogi carcinoma tumor was used to assess the influence of tumor size on the response to flutamide treatment. Two weeks after subcutaneous inoculation of tumor fragments in Shionogi mice, six groups of animals bearing SC-115 tumors ranging from 0.1 to 1.8 cm in diameter were treated with flutamide (1 mg, twice daily). The castrated mice received an androstenedione (delta4-dione) implant to mimic the human situation, where the adrenals produce precursor steroids which are transformed into androgens in peripheral intracrine tissues. After 16 days, treatment with flutamide inhibited tumor growth by 32 to 57% in the four groups of mice having tumors ranging from 0.1 to 1.0 cm in diameter at day 0, whereas no significant inhibitory effect was observed in larger tumors. The same treatment, however, caused potent inhibitory effects on other androgen-sensitive parameters, namely prostatic and seminal vesicle weight and kidney ornithine decarboxylase (ODC) activity, the effect on these parameters being similar in all groups of animals, irrespective of tumor size. Furthermore, when those larger tumors unresponsive to antiandrogenic treatment were cut into small fragments and inoculated into new groups of mice, the same treatment with flutamide efficiently inhibited tumor growth, treatment being started at tumor sizes of 0.1 to 0.3 cm in diameter. The present data clearly demonstrate that small tumors are highly sensitive to androgen deprivation, while loss of response develops with increasing tumor size, thus indicating that, for optimal efficacy, androgen blockade should be given at the early stages of prostate cancer.

Animals↗
PubMed1996

Vinyl fluoride as a mimic of the "intermediate' enol form in the 5 alpha-reductase transformation: synthesis and in vitro activity of (N-1',1'-dimethylethyl)-3-haloandrost-3,5-diene-17 beta-carboxamides.

(N-1',1'-Dimethylethyl)-3-haloandrost-3,5-diene-17 beta-carboxamides (9-11) and the methyl ester 8 were prepared from 3-chloro/bromoandrost-3,5-diene-17 beta-carboxylic chloride/bromide (6/7), which were obtained from pregnenolone. In comparison with finasteride and 4-MA, compounds 8-11 showed very weak inhibitory activity ( < or = 10% inhibition) on human type I 5 alpha-reductase (transfected 293 cells) at 100 and 1000 nM concentrations. Against the type II enzyme, chloro compounds 8 and 9, and bromo 10 had no effect at 100 nM concentration, however, they were weak inhibitors of the type II (6.0% < inhibition < 30%) at a higher concentration. The best activity (IC50 = 480 nM) was observed with the 3-vinyl fluoride analogue 11.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1996

Diagnosis of advanced or noncurable prostate cancer can be practically eliminated by prostate-specific antigen.

OBJECTIVES: To determine the percentage of localized and potentially curable prostate cancers diagnosed at follow-up screening visits compared with the first screening visit. METHODS: Within the context of a prospective screening study performed in randomly chosen men aged between 45 and 80 years, up to 6-year follow-up screening visits have been performed with serum prostate-specific antigen (PSA) measurement and digital rectal examination (DRE) followed by transrectal ultrasonography of the prostate when PSA or DRE is abnormal. RESULTS: Of the 117 prostate cancers diagnosed at 14,554 annual follow-up visits, only 1 cancer (0.9%) was metastatic compared with 8% (26/322) at 8029 first visits. Moreover, 97% of the cancers detected at follow-up visits could be identified by PSA alone compared with 86% at first visit. The incidence of 0.8% per year during 15 years of screening between the ages of 55 and 70 years would diagnose localized prostate cancer in 12% of the population, a value not too different from the 10% diagnosed with prostate cancer during life-time in the absence of screening. CONCLUSIONS: The present data show that annual screening with PSA diagnoses clinically localized prostate cancer in more than 95% of cases, thus almost completely eliminating the diagnosis of metastatic prostate cancer. Moreover, the number of prostate cancers diagnosed is not significantly increased by screening.

Aged↗
PubMed1996

The complete BRCA2 gene and mutations in chromosome 13q-linked kindreds.

Breast carcinoma is the most common malignancy among women in developed countries. Because family history remains the strongest single predictor of breast cancer risk, attention has focused on the role of highly penetrant, dominantly inherited genes in cancer-prone kindreds (1). BRCA1 was localized to chromosome 17 through analysis of a set of high-risk kindreds (2), and then identified four years later by a positional cloning strategy (3). BRCA2 was mapped to chromosomal 13q at about the same time (4). Just fifteen months later, Wooster et al. (5) reported a partial BRCA2 sequence and six mutations predicted to cause truncation of the BRCA2 protein. While these findings provide strong evidence that the identified gene corresponds to BRCA2, only two thirds of the coding sequence and 8 out of 27 exons were isolated and screened; consequently, several questions remained unanswered regarding the nature of BRCA2 and the frequency of mutations in 13q-linked families. We have now determined the complete coding sequence and exonic structure of BRCA2 (GenBank accession #U43746), and examined its pattern of expression. Here, we provide sequences for a set of PCR primers sufficient to screen the entire coding sequence of BRCA2 using genomic DNA. We also report a mutational analysis of BRCA2 in families selected on the basis of linkage analysis and/or the presence of one or more cases of male breast cancer. Together with the specific mutations described previously, our data provide preliminary insight into the BRCA2 mutation profile.

BRCA2 Protein↗
PubMed1996

Isolation and characterization of a stereospecific 3beta-hydroxysteriod sulfotransferase (pregnenolone sulfotransferase) cDNA.

In contrast to humans, who possess a hydroxysteroid sulfotransferase (HSST), namely, DHEA sulfotransferase (DHEA-ST), that displays broad substrate specificities, HSSTs of the guinea pig show a high substrate stereoselectivity, as shown by the recent cloning of a chiral-specific 3alpha-hydroxysteroid sulfotransferase. Herein, we report the cloning and expression of the substrate and chiral-specific pregnenolone sulfotransferase (PREG-ST). Transfection of the pCMV expression vector containing PREG-ST cDNA in transformed human embryonal kidney (293) cells showed that the expressed enzyme selectively catalyzes the 3beta-hydroxysteroid substrate. It converts pregnenolone to pregnenolone sulfate most efficiently, whereas dehydroepiandrosterone and epiandrosterone were transformed at a much lower rate, and androsterone, a 3alpha-hydroxysteroid, was not significantly metabolized (30-fold lower). Thus, the enzyme was identified as pregnenolone sulfotransferase. DNA analysis predicts a protein of 287 amino acids with a calculated molecular mass of 34,199 daltons. Alignment of the amino acid sequence with other sulfotransferases indicated that guinea pig pregnenolone sulfotransferase shares 75 and 80% homology with human DHEA sulfotransferase and rat hydroxysteroid dehydrogenase, respectively. RNA blot analysis using guinea pig liver, intestine, adrenal, kidney, epididymis, testis, and lung showed a single RNA species at 1.3 kb is expressed in liver, intestine, and kidney. Guinea pig 3beta-hydroxysteroid sulfotransferase is thus different from that in humans, who possess two mRNA species of 1.3 and 1.8 kb.

Amino Acid Sequence↗
PubMed1996

Comparison of BRCA1 polymorphisms, rare sequence variants and/or missense mutations in unaffected and breast/ovarian cancer populations.

Inherited mutations in the BRCA1 gene are known to confer a predisposition to breast and ovarian cancer. We have first characterized 19 sequence variants in the BRCA1 gene during mutation screening by direct sequencing using DNA samples from breast/ovarian cancer patients or obligate carriers. The frequencies of these sequence variants were then compared with those found in control populations of women. Among the 10 sequence variants showing an estimated frequency of the less common allele above 0.05, Q/R356, L/P871, E/G1038, K/R1183 and S/G1613 result in a change of amino acids, 2201C/T, 2430T/C and 4427C/T are silent mutations and the two others, 4209-141C/A and 5272 + 66A/G, are intronic polymorphisms. These frequent polymorphisms, with the exception of Q/R356, were in complete or significant pairwise linkage disequilibrium as evaluated in our control populations. With one exception (L/P871), none of these variants had statistically significant (P < 0.05) differences in allele frequency between breast/ovarian cancer patients or obligate carriers and our control populations. Four rare sequence variants designated 710C-->T, D693N, R841W and S1040N were found in both unaffected and breast/ovarian cancer populations, while the missense mutations M1008I, E1219D, R1347G, T1561I and M1628V were detected only once in our patient population. When a functional test is available, it will be important to determine the consequence on the BRCA1 activity of these rare sequence variants and missense mutations.

BRCA1 Protein↗
PubMed1996

Effect of neoadjuvant endocrine therapy (combined androgen blockade) on normal prostate and prostatic carcinoma. A randomized study.

The morphologic changes induced by neoadjuvant combination endocrine therapy were evaluated in prostatectomy specimens from patients diagnosed with localized prostate cancer. These patients participated in a prospective, randomized clinical trial investigating the effect of 3 months of combination therapy with flutamide and an LHRH agonist prior to radical prostatectomy versus radical prostatectomy alone. Ninety-six radical prostatectomy specimens processed according to the same protocol were evaluated without knowledge of prior treatment. Forty-seven patients were randomly assigned to the neoadjuvant combination therapy group and 49 to the control arm. Compared with the control group, several changes were strongly and significantly associated with exposure to neoadjuvant combination therapy. The nonmalignant prostatic tissue showed strong prominence and hyperplasia of the basal cell layer, accompanied by epithelial cell vacuolization and markedly reduced occurrence of prostatic intraepithelial neoplasia (p < 0.001) after combination therapy. Prostate cancer tissue, on the other hand, showed smaller nucleoli (p < 0.001), cell vacuolization (p < 0.001), rare intraluminal crystalloids (p < 0.001), higher Gleason grade (p < 0.001), lower prevalence of capsular penetration (p < 0.001), and less frequent invasion of the perineural spaces (p < 0.001) and surgical margins (p = 0.002). Tumor volume, was also reduced by more than 40% in the treated group (p = 0.007). The present findings show that preoperative endocrine combination therapy induces highly characteristic changes in both nonmalignant and cancerous prostatic tissue. Furthermore, following endocrine treatment, the surgical margins are less likely to be involved by cancer and capsular penetration is reduced.

Adult↗
PubMed1996

Localization and regulation of expression of the FAR-17A gene in the hamster flank organs.

A quantitative in situ hybridization study was carried out to determine the precise localization and androgen regulation of the flank organ regulated (FAR-17A) mRNA expression in the different cellular components of the hamster flank organs. Although FAR-17A mRNA was highly expressed in the epithelial cells of the sebaceous glands, it was also found in the outer root sheath of the hair follicles and in melanocytes. The changes in FAR-17A mRNA levels, in the size of the flank organ and sebaceous gland areas as well as in the weight of the seminal vesicles and prostate, were compared following castration and after 5alpha-dihydrotestosterone treatment. FAR-17A mRNA levels were already significantly decreased 1 d after castration, in parallel with a concomitant decrease in the number of labeled cells with the FAR-17A probe. A maximal decrease was found 7 d after castration. The other parameters were significantly reduced later. After 7 d of treatment with dihydrotestosterone, all values returned to those found in intact animals. Similar stimulatory effects on these parameters were observed after treatment with the adrenal sex steroid precursor dehydroepiandrosterone. These data show that all of the components of the flank organs (sebaceous glands, hair follicles, and melanocytes) express the flank organ regulated (17A) type gene (FAR-17A) gene and that its expression is stimulated by treatment with either dihydrotestosterone or dehydroepiandrosterone. Moreover, FAR-17A mRNA levels respond to androgen stimulation more rapidly than the standard morphologic parameters, revealing that the FAR-17A gene could be a more sensitive and cell specific marker to study the mechanisms of androgen action in the skin.

Androgens↗