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Biomedical subjects

Rosalia C M Simmen

Publications and source records attributed to Rosalia C M Simmen.

At least 19 recordsLinked to original sources
PubMed2006

In utero exposure to maternal diets containing soy protein isolate, but not genistein alone, protects young adult rat offspring from NMU-induced mammary tumorigenesis.

The linkage of nutrition and cancer prevention is an intriguing concept that is gaining widespread support. Here, we investigated the influence of developmental context on dietary protection against tumorigenesis initiated by the direct-acting carcinogen N-methyl-N-nitrosourea (NMU), and examined potential mechanisms underlying these effects. Rats were exposed only in utero or for lifetime to American Institute of Nutrition-93G diets made with casein (CAS), soy protein isolate (SPI) or CAS supplemented with genistein (GEN). Mammary glands of post-natal day (PND) 50 rats prior to NMU administration were examined for apoptotic status, pro-apoptotic gene expression and immunoreactive phosphatase and tensin homolog deleted on chromosome ten (PTEN) and epithelial cadherin (E-cadherin) levels, whereas mammary tumor parameters were evaluated 99 days post-NMU. Animals exposed only in utero to SPI had increased tumor latency, decreased tumor multiplicity and lower higher grade tumors, than those fed CAS. In utero exposure to GEN resulted in similar tumor parameters as the CAS group, whereas lifetime SPI exposure decreased tumor incidence that was not mimicked by in utero exposure alone. Mammary glands of PND50 rats fed lifetime SPI had increased terminal end bud apoptotic status and PTEN expression, than the other diet groups. Rats exposed only in utero to SPI or GEN had higher membrane E-cadherin in mammary structures than those lifetime-fed CAS or SPI. Thus, limited exposure during gestation to SPI can positively influence resistance to chemically induced mammary tumorigenesis later in life. Preventative strategies against mammary and other types of cancer might be uncovered by refinement of the developmental window for dietary factor exposure.

Animals↗
PubMed2006

Enhancer- and silencer-like sequences that mediate insulin-like growth factor-binding protein-2 gene expression in uterine cells of pregnancy.

The regulation of insulin-like growth factor-binding protein-2 (IGFBP-2) gene transcription in specific cell and developmental contexts is not well understood. Here, we identified DNA regions that mediate IGFBP-2 gene transcription in two of the three major cell types of the uterine endometrium of the early pregnant pig. Two clusters of transcriptional start sites at nucleotides -109/-105 and -96/-87 (+1, translational initiation site) in the porcine IGFBP-2 gene were localized in uterine endometrium and in primary cultures of endometrial glandular epithelial (GE) and stromal (ST) fibroblastic cells. Upstream regions of this gene (spanning -1,397/+73) were fused to a luciferase reporter gene, and the constructs were transiently transfected into endometrial GE and ST cells representative of pregnancy days 12 and 18 (day 115 = parturition). A short (110 bp) upstream region (-874/-765) stimulated the IGFBP-2 and heterologous SV40 promoters in the two cell types at both pregnancy days. Two noncontiguous copies of the novel sequence motif TCAGGG within the 110-bp fragment were implicated in transcriptional activity, since block mutation of these sequences led to a repression of SV40 basal promoter activity in endometrial cells. Southwestern blotting identified an endometrial nuclear protein of 34-kDa molecular weight that bound an oligonucleotide containing this motif, and EMSA suggested robust expression of this protein in early pregnancy endometrium and in ovary but at much reduced levels in endometrium at later pregnancy. A pair of E-box elements (CANNTG) within the 110 bp region was stimulatory to IGFBP-2 promoter activity; block mutation of these converted the 110-bp region into a potent transcriptional silencer in all but day 18 ST cells. Results identify novel DNA motifs that regulate the IGFBP-2 gene promoter in uterine endometrium in pregnancy-associated fashion.

Animals↗
PubMed2006

Tp53-associated growth arrest and DNA damage repair gene expression is attenuated in mammary epithelial cells of rats fed whey proteins.

Dietary protection from mammary cancer is likely coordinated through multiple signaling pathways, based on the known heterogeneity of the disease and the distinct origins of mammary tumor cells. The present study examined the modulatory effects of dietary intake of whey protein hydrolysate (WPH) relative to casein (CAS), on mammary epithelial cell resistance to endogenous DNA damage using Tp53 gene expression and signaling as a read-out, and on systemic proapoptotic and immune surveillance activity, in young adult female Sprague-Dawley rats. Rats were fed AIN-93G diets made with CAS or WPH as the sole protein source beginning at gestation d 4. At postnatal day (PND) 50, mammary glands of rats fed WPH had lower levels of activated Tp53 and p38 mitogen-activated protein kinase proteins, and reduced transcript levels for Tp53-associated DNA damage repair, growth arrest, and proapoptotic genes than those of CAS-fed rats. Serum from WPH-fed rats had greater apoptotic activity in MCF-7 tumor cells than that from rats fed CAS. Serum levels of monocyte chemoattractant protein (MCP)-1 were higher in WPH- than in CAS-fed rats. MCF-7 cells treated with CAS serum + recombinant rat MCP-1 had apoptotic activity and Tp53 and p21 gene expression levels comparable to those treated with WPH serum or recombinant MCP-1. Results indicate that mammary glands of rats fed a WPH diet are more protected from endogenous DNA damage than are those of CAS-fed rats, and identify MCP-1 as a potential serum biomarker for the positive effects of healthy diets.

Administration, Oral↗
PubMed2006

Tumor-protective and tumor-promoting actions of dietary whey proteins in an N-methyl-N-nitrosourea model of rat mammary carcinogenesis.

The mammary tumor-protective effects of dietary factors are considered to be mediated by multiple signaling pathways, consistent with the heterogeneous nature of the disease and the distinct genetic profiles of tumors arising from diverse mammary cell populations. In a 7,12-dimethylbenz(a)anthracene-induced model of carcinogenesis, we showed previously that female Sprague-Dawley rats exposed to AIN-93G diet containing whey protein hydrolysate (WPH) beginning at gestation Day 4 had reduced tumor incidence than those exposed to diet containing casein (CAS), due partly to increased mammary differentiation and reduced activity of phase I metabolic enzymes. Here, we evaluated the tumor-protective effects of these same dietary proteins to the direct-acting carcinogen N-methyl-N-nitrosourea (NMU). We found that lifetime exposure to WPH, relative to CAS, decreased mammary tumor incidence and prolonged the appearance of tumors in NMU-treated female rats, with no corresponding effects on tumor multiplicity. At 115 days post-NMU, histologically normal mammary glands from WPH-fed tumor-bearing rats had increased gene expression for the tumor suppressor BRCA1 and the differentiation marker kappa-casein than those of CAS-fed tumor-bearing rats. Tumor-bearing rats from the WPH group had more advanced tumors, with a greater incidence of invasive ductal carcinoma than ductal carcinoma in situ and higher serum C-peptide levels than corresponding rats fed CAS. WPH-fed tumor-bearing rats were also heavier after NMU administration than CAS tumor-bearing rats, although no correlation was noted between body weight and C-peptide levels for either diet group. Results demonstrate the context-dependent tumor-protective and tumor-promoting effects of WPH; provide support for distinct signaling pathways underlying dietary effects on development of mammary carcinoma; and raise provocative questions on the role of diet in altering the prognosis of existing breast tumors.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2005

Progesterone receptor transactivation of the secretory leukocyte protease inhibitor gene in Ishikawa endometrial epithelial cells involves recruitment of Krüppel-like factor 9/basic transcription element binding protein-1.

Progesterone receptor (PR), a ligand-inducible transcription factor, mediates the physiological actions of progesterone (P) through two distinct isoforms, PR-A and PR-B, and numerous nuclear coregulators. We previously demonstrated that basic transcription element binding protein-1 (BTEB1), a transcription factor of the Krüppel-like family, is a functional PR-interacting protein, based on the subfertility phenotype and reduced P sensitivity of uterine PR target genes, on BTEB1 null mutation. Here we examined the role of BTEB1 in PR-mediated signaling in endometrial epithelial cells using Ishikawa human endocarcinoma cells and the P-responsive secretory leukocyte protease inhibitor (SLPI) gene. Treatment of Ishikawa cells with P for 24 h increased SLPI and BTEB1 transcript levels without similar effects on PR expression. P induction was abolished by the PR antagonist RU486, whereas knockdown of BTEB1 with short interfering RNA reduced P-responsive BTEB1 but not SLPI expression to basal levels. Forced expression of BTEB1, either by stable or transient transfections of BTEB1 expression constructs in endometrial carcinoma cells, enhanced SLPI promoter activity. Chromatin immunoprecipitation with anti-BTEB1 antibody demonstrated BTEB1 recruitment to the proximal GC-rich containing SLPI promoter region (-97 to -86) in human endometrial carcinoma (Hec1A) cells overexpressing BTEB1. In Ishikawa cells, recruitment of BTEB1 to the proximal, GC-rich region and the distal, progesterone-responsive element-like containing region (-635 to -514) was P dependent and was accompanied by corecruitment of PR and the PR coactivator cAMP-response element binding protein-binding protein. PR-B, rather than PR-A isoform, preferentially associated with BTEB1 in the GC-rich region, whereas both PR isoforms were recruited to the progesterone-responsive element-like site along with BTEB1. Our findings define a novel pathway for BTEB1/PR cross-talk to facilitate P-dependent gene transcription in endometrial epithelial cells.

Cell Line, Tumor↗
PubMed2005

Null mutation of Kruppel-like factor9/basic transcription element binding protein-1 alters peri-implantation uterine development in mice.

Female mice null for the basic transcription element binding protein-1 (Bteb1) gene have reduced numbers of implanting embryos. We hypothesized that the implantation defect, resulting in subfertility, is a consequence of developmental asynchrony between the embryo and uterine endometrium at peri-implantation. To address this, endometrium from wild-type (WT) and Bteb1(-/-) females at 0.5 to 5.5 days postcoitum (dpc) were evaluated for proliferation (BrdU labeling), apoptosis (TUNEL), and steroid hormone receptor expression (immunohistochemistry). Loss of BTEB1 did not affect serum estrogen (E) and progesterone (P) levels. In stroma (ST), the numbers of progesterone receptor (PGR) and HomeoboxA10 (HOXA10)-expressing cells were lower (3.5 and 4.5 dpc), while those of estrogen receptor-alpha (ESR1) were higher (3.5 dpc), with Bteb1 ablation. The peak of proliferation in luminal epithelium (LE), glandular epithelium (GE), and ST was delayed, while the apoptotic index in all cell types was increased (2.5 dpc) in Bteb1(-/-) relative to WT mice. The numbers of PGR-positive ST cells was negatively correlated with LE proliferation in WT mice; this correlation was lost in Bteb1(-/-) mice and was not observed before 2.5 dpc for both genotypes. Proliferation and apoptosis in all endometrial compartments, as well as the numbers of PGR-, HOXA10-, and ESR1-expressing ST cells, were lower in Bteb1(-/-) relative to WT mice after ovariectomy and E + P treatment. Results suggest that BTEB1, by regulating ST PGR expression and transactivation, participates in the paracrine control of LE proliferation by PGR and thus is important for establishment of a receptive uterus critical for successful implantation.

Animals↗
PubMed2005

The soy isoflavone genistein promotes apoptosis in mammary epithelial cells by inducing the tumor suppressor PTEN.

The isoflavone genistein (GEN), a biologically active component of soy foods, is associated with reduced breast cancer risk in women who consume soy-rich diets. GEN has been reported to influence many biological processes, of which suppression of cell proliferation and stimulation of apoptosis are considered to be the major pathways underlying its inhibition of tumorigenesis. This study evaluated the mechanism by which diets containing GEN promote mammary epithelial cell death. We report that mammary glands of young adult female rats exposed from gestation day 4 to postnatal day 50, to AIN-93G diets containing as sole protein source, casein (CAS) supplemented with GEN, or soy protein isolate (SPI+) had increased apoptosis, relative to rats fed CAS diet devoid of GEN. Mammary gland proliferation was unaffected by diet. The increased apoptotic index in mammary glands of GEN and SPI+ rats was accompanied by increased levels of the tumor suppressor protein PTEN (phosphatase and tensin homolog deleted in chromosome ten), albeit enhanced mammary expression of the pro-apoptotic p21, Bax and Bok genes was observed only in GEN-fed rats. GEN-induced apoptosis in MCF-7 cells was concomitant with increased PTEN expression, and this was abrogated by PTEN siRNA. MCF-7 cells treated with serum from GEN- or SPI(+)-fed rats had increased apoptosis as well as increased levels of the PTEN transcript. PTEN siRNA attenuated the increased apoptotic response of MCF-7 cells to serum from rats fed SPI+ or GEN, although the inhibition to basal (CAS serum) apoptotic levels was achieved only for cells treated with GEN serum. Decreased p21 and Bok gene expression accompanied the inhibition of apoptosis by PTEN siRNA. Data implicate PTEN in the induction of apoptosis by GEN and suggest that the promotion of apoptosis leading to inhibition of tumorigenesis in vivo by diets containing GEN may also involve the distinct activities of yet unknown GEN metabolite(s) and/or other systemic factors induced by GEN.

Animals↗
PubMed2005

Uterine phenotype of young adult rats exposed to dietary soy or genistein during development.

Dietary soy intake is associated with protection from breast cancer, but questions persist on the potential risks of the major soy isoflavone genistein (GEN) on female reproductive health. Here, we evaluated intermediate markers of cancer risk in uteri of cycling, young adult Sprague-Dawley rats lifetime exposed to one of three AIN-93G semipurified diets: casein (CAS), soy protein isolate (SPI+ with 276 mg GEN aglycone equivalents/kg) and CAS+GEN (GEN at 250 mg/kg). Postnatal day 50 (PND50) rats lifetime exposed to GEN or SPI+ had similar uterine luminal epithelium height, myometrial thickness, endometrial gland numbers, endometrial immunoreactive proliferating cell nuclear antigen (PCNA), and serum estrogen and progesterone, as CAS-fed rats. GEN-fed rats showed modestly increased apoptosis in uterine glandular epithelium, compared to those of CAS- or SPI+-fed groups. Diet had no effect on the uterine expression of genes for the tumor suppressors PTEN, p53 and p21, and the apoptotic-associated proteins Bcl2, Bax and progesterone receptor. Uterine tissue and serum concentrations of total GEN were higher in rats fed GEN than in those fed SPI+. Human Ishikawa endocarcinoma cells treated with GEN-fed rat serum tended to exhibit increased apoptotic status than those treated with CAS-fed rat serum. Exogenously added GEN (0.2 and 2 microM) increased, while estradiol-17beta (0.1 microM) decreased Ishikawa cell apoptosis, relative to untreated cells. Results suggest that lifetime dietary exposure to soy foods does not alter uterine cell phenotype in young adult rats, while GEN, by enhancing uterine endometrial glandular apoptosis in vivo and in vitro, may confer protection against uterine carcinoma. Given its limited influence on uterine phenotype of young adult females, GEN, when taken as part of soy foods or as supplement, should be favorably considered for other potential health benefits.

Animals↗
PubMed2005

Soy protein isolate and protection against cancer.

OBJECTIVE: Results from epidemiological and animal studies suggest that consuming soy-containing diets reduces the incidence of certain cancers. The purpose of this presentation was to evaluate the potential of soy protein to prevent occurrence of prostate, breast and colon cancer. METHODS: Meta-analyses of published epidemiologic studies associating cancer risk with soy intake were performed. The incidence of chemically-induced mammary or colon tumors was determined for rats fed AIN-93G diets made with either casein or soy protein isolate (SPI). Western and Northern blot and microarray analyses were performed on rat mammary and colon tissues to study mechanisms underlying the effects of soy. RESULTS: Meta-analyses revealed reductions in the mean overall risk estimate for mammary (0.78, p < 0.001), colon (0.70, p < 0.001) and prostate (0.66, p < 0.001) cancer for soy consumers. The incidence of AOM-induced colon tumors and DMBA-induced mammary tumors was reduced (p < 0.05) in rats fed SPI-containing diets. Lower incidence of mammary tumors in SPI-fed rats was associated with: 1) reduced terminal end bud numbers (p < 0.05), 2) lower expression of the phase I enzyme CYP1B1 (p < 0.05) and 3) reduced expression of the Ah Receptor and ARNT (p < 0.05). CONCLUSIONS: SPI may protect against cancer via multiple mechanisms, including: 1) increased mammary gland differentiation, 2) decreased activation of procarcinogens to carcinogens and 3) regulation of genes in signal transduction pathways underlying tumor initiation, promotion and/or progression.

Animals↗
PubMed2004

Inhibition of NMU-induced mammary tumorigenesis by dietary soy.

We previously demonstrated that female Sprague-Dawley rats fed AIN-93G diets containing soy protein isolate (SPI+) had lower DMBA-induced mammary tumor incidence than those fed diets containing casein (CAS), due partly to altered Phase I metabolism with soy. Here, we evaluated the tumor protective effects of these same diets to the direct-acting carcinogen N-methyl-nitrosourea (NMU). Tumor incidence was reduced and tumor latency was enhanced, in NMU-administered female rats lifetime exposed to SPI+, relative to the CAS group. Tumor multiplicity did not differ with diet, while tumor grade tended to be more advanced with SPI+. Normal mammary glands of CAS and SPI+ tumor-bearing rats had comparable proliferative and apoptotic status. However, mammary expression of HER-2/neu and progesterone receptor (PR) genes was higher for SPI+ rats. Moreover, tumored SPI+ rats had lower serum progesterone levels than those fed CAS, while serum estrogen did not differ. Serum from tumored SPI+ rats had higher apoptotic activity towards mammary epithelial MCF-7 cells, than CAS serum. Thus, dietary soy protects against mammary tumorigenesis induced by a direct-acting carcinogen and alters signaling pathways involving PR and HER-2/neu.

Alkylating Agents↗
PubMed2004

The planetary biology of cytochrome P450 aromatases.

BACKGROUND: Joining a model for the molecular evolution of a protein family to the paleontological and geological records (geobiology), and then to the chemical structures of substrates, products, and protein folds, is emerging as a broad strategy for generating hypotheses concerning function in a post-genomic world. This strategy expands systems biology to a planetary context, necessary for a notion of fitness to underlie (as it must) any discussion of function within a biomolecular system. RESULTS: Here, we report an example of such an expansion, where tools from planetary biology were used to analyze three genes from the pig Sus scrofa that encode cytochrome P450 aromatases-enzymes that convert androgens into estrogens. The evolutionary history of the vertebrate aromatase gene family was reconstructed. Transition redundant exchange silent substitution metrics were used to interpolate dates for the divergence of family members, the paleontological record was consulted to identify changes in physiology that correlated in time with the change in molecular behavior, and new aromatase sequences from peccary were obtained. Metrics that detect changing function in proteins were then applied, including KA/KS values and those that exploit structural biology. These identified specific amino acid replacements that were associated with changing substrate and product specificity during the time of presumed adaptive change. The combined analysis suggests that aromatase paralogs arose in pigs as a result of selection for Suoidea with larger litters than their ancestors, and permitted the Suoidea to survive the global climatic trauma that began in the Eocene. CONCLUSIONS: This combination of bioinformatics analysis, molecular evolution, paleontology, cladistics, global climatology, structural biology, and organic chemistry serves as a paradigm in planetary biology. As the geological, paleontological, and genomic records improve, this approach should become widely useful to make systems biology statements about high-level function for biomolecular systems.

Amino Acid Sequence↗
PubMed2004

Subfertility, uterine hypoplasia, and partial progesterone resistance in mice lacking the Kruppel-like factor 9/basic transcription element-binding protein-1 (Bteb1) gene.

Progesterone receptor (PR), a ligand-activated transcription factor, is a key regulator of cellular proliferation and differentiation in reproductive tissues. The transcriptional activity of PR is influenced by co-regulatory proteins typically expressed in a tissue- and cell-specific fashion. We previously demonstrated that basic transcription element-binding protein-1 (BTEB1), a member of the Sp/Krüppel-like family of transcription factors, functionally interacts with the two PR isoforms, PR-A and PR-B, to mediate progestin sensitivity of target genes in endometrial epithelial cells in vitro. Here we report that ablation of the Bteb1 gene in female mice results in uterine hypoplasia, reduced litter size, and increased incidence of neonatal deaths in offspring. The reduced litter size is solely a maternal genotype effect and results from fewer numbers of implantation sites, rather than defects in ovulation. In the early pregnant uterus, Bteb1 expression in stromal cells temporally coincides with PR-A isoform-dependent decidual formation at the time of implantation. Expression of two implantation-specific genes, Hoxa10 and cyclin D3, was decreased in uteri of early pregnant Bteb1-null mutants, whereas that of Bteb3, a related family member, was increased, the latter possibly compensating for the loss of Bteb1. Progesterone responsiveness of several uterine genes was altered with Bteb1-null mutation. These results identify Bteb1 as a functionally relevant PR-interacting protein and suggest its selective modulation of cellular processes that are regulated by PR-A in the uterine stroma.

Animals↗
PubMed2004

Uterine androgen receptors: roles in estrogen-mediated gene expressionand DNA synthesis.

The localization of androgen receptors (AR) and their ligands in the uterine microenvironment at early pregnancy suggest a role for AR in uterine physiology. We have evaluated AR expression in the pig uterine endometrium and examined whether AR ligands modulate peri-implantation uterine gene expression. Northern blot analysis demonstrated the approximately 10.5 kilobase AR transcript in endometrium. Endometrial levels of AR mRNA and protein were greater at early than at mid- or late pregnancy. Estrogen receptor-alpha mRNA levels showed similar maximal expression at early pregnancy. Immunocytochemical analysis of endometrium at early pregnancy localized AR to nuclei of glandular epithelial (GE) and stromal (ST) cells. To evaluate a role for AR in uterine gene regulation, the levels of mRNAs for insulin-like growth factor-I (IGF-I), proliferative cell nuclear antigen (PCNA), and AR itself were assessed in uterine endometrial explant cultures treated with estradiol-17beta (E), testosterone (T), and 19-nortestosterone (N). Induction by E of AR mRNA abundance occurred in endometrium from Day 10 but not from Day 12 pregnant animals and this was partially blocked by coaddition of N or T, although neither androgen alone had any effect. Abundance of IGF-I and PCNA mRNAs was increased by E and inhibited by coaddition of either T or N in Day 10 pregnant pig endometrium. In endometrium from Day 12 pregnant animals, addition of either N or T with E increased IGF-I mRNA levels over that of controls, although E alone was without effect. In contrast, PCNA mRNA abundance was suppressed by all steroid treatments in these explants. DNA synthesis in primary cultures of GE cells from endometrium at Days 10 and 12 of pregnancy was increased by E and was suppressed by T, the latter only at Day 12. E did not affect DNA synthesis in ST cells from endometrium at either pregnancy day, although T inhibited this process in an E-dependent manner in ST cells from pregnancy Day 12. Results identify AR in the pig endometrium during the window of maternal receptivity for implantation and demonstrate the functional, albeit complex, interactions of androgens and estrogens in the regulation of uterine endometrial gene expression and cell growth in vitro. Further elucidation of the role of androgens and their receptor in early pregnancy events may be relevant to an understanding of peri-implantation embryo loss.

Androgens↗
PubMed2004

Dietary exposure to whey proteins alters rat mammary gland proliferation, apoptosis, and gene expression during postnatal development.

We have found that AIN-93G diets made with whey protein hydrolysate (WPH) reduce 7,12-dimethyl-benz[a]anthracene (DMBA)-induced tumor incidence in Sprague-Dawley (Harlan) rats relative to those fed a diet with casein (CAS). Herein, we replicated these findings in another Sprague-Dawley substrain (Charles River) and examined whether WPH protective effects were associated with altered mammary gland differentiation status and expression of the tumor suppressor phosphatase and tensin homolog deleted in chromosome ten (PTEN). Mammary tumor incidence was lower in DMBA-treated rats fed WPH than in those fed CAS. Mammary glands of WPH- and CAS-fed rats were isolated at weaning [postnatal day (PND) 21-28] and at an early adult stage (PND 50-53) and analyzed for proliferative (proliferating cell nuclear antigen immunoreactivity), apoptotic (terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick-end labeling), and differentiation (beta-casein) indices, as well as for PTEN mRNA and protein levels. PND 50-53 rats fed WPH showed decreased proliferation and increased apoptosis in mammary structures, coincident with increased mammary beta-casein gene expression, decreased terminal end-bud numbers, and increased ductal lengths, relative to same-age CAS-fed rats. When challenged with DMBA for 24 h, mammary glands of PND 53 CAS-fed rats had decreased cell survival in both terminal end buds and ductal epithelium, while the mammary glands of WPH-fed rats were not altered from pre-DMBA levels. At 7 d post-DMBA, mammary glands of CAS- and WPH-fed rats exhibited comparable apoptotic indices. Mammary PTEN expression was higher in WPH- than in CAS-fed rats at PND 21-28, but was not different in young adults fed either diet. Results demonstrate that dietary WPH advances mammary gland differentiation during neonatal development and suggest that the transiently increased expression of the pro-apoptotic signal PTEN during a sensitive developmental window may partly underlie the cancer protective effects of WPH.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2003

Selective interactions of Kruppel-like factor 9/basic transcription element-binding protein with progesterone receptor isoforms A and B determine transcriptional activity of progesterone-responsive genes in endometrial epithelial cells.

The Sp/KLF transcription factor basic transcription element-binding protein (BTEB1) regulates gene transcription by binding to GC-rich sequence motifs present in the promoters of numerous tissue-specific as well as housekeeping genes. Similar to other members of this family, BTEB1 can act as a transactivator or transrepressor depending on cell and promoter context, although the molecular mechanism underlying these distinct activities remains unclear. Here we report that BTEB1 can mediate signaling pathways involving the nuclear receptor for the steroid hormone progesterone in endometrial epithelial cells by its selective interaction with the progesterone receptor (PR) isoforms, PR-A and PR-B. Functional interaction with ligand-activated PR-B resulted in superactivation of PR-B transactivity, facilitated the recruitment of the transcriptional integrator CREB-binding protein within the PR-dimer, and was dependent on the structure of the ligand bound by PR-B. By contrast, BTEB1 did not influence agonist-bound PR-A transactivity, although it augmented PR-A inhibition of PR-B-mediated transactivation as well as potentiated ligand-independent PR-A transcriptional activity in the presence of CREB-binding protein. We also demonstrate similar positive modulatory actions of BTEB1-related family members Krüppel-like family (KLF) 13/FKLF2/BTEB3 and Sp1 on PR-B transactivity. Further, we provide support for the potential significance of the selective functional interactions of PR isoforms with BTEB1 in the peri-implantation uterus using mouse and pig models and in the breast cancer cell lines MCF-7 and T47D. Our results suggest a novel mechanism for the divergent physiological consequences of PR-A and PR-B on progesterone-dependent gene transcription in the uterus involving select KLF members.

Animals↗
PubMed2002

Progesterone receptors and Sp/Krüppel-like family members in the uterine endometrium .

Sp/KLF family members, of which at least 20 distinct nuclear proteins are known to date, serve as transcription factors by binding to GC-enriched sites within target gene promoters. These molecules regulate diverse cellular processes such as proliferation, differentiation, and apoptosis, via their interactions with various other nuclear proteins in promoter- and cell-context-dependent pathways to effect transactivation or transrepression. Recent studies indicate that Sp-family members may functionally interact with ligand-activated nuclear receptors, especially those for steroid hormones. This review provides a discussion of the putative mechanisms and important participants involved in the crosstalk between selected members of this family and the receptor for the pregnancy hormone progesterone, and the relevant outcomes to the control of the transcriptional network in the uterine endometrium.

Animals↗
PubMed2002

Secretory leukocyte protease inhibitor mediates proliferation of human endometrial epithelial cells by positive and negative regulation of growth-associated genes.

Secretory leukocyte protease inhibitor (SLPI) inhibits chymotrypsin, trypsin, elastase, and cathepsin G. This protein also exhibits proliferative effects, although little is known about the molecular mechanisms underlying this activity. We have generated SLPI-ablated epithelial sublines by stably transfecting the Ishikawa human endometrial cell line with an antisense human SLPI RNA expression vector. We demonstrate a positive correlation between cellular SLPI production and proliferation. We further show that Ishikawa sublines expressing low to undetectable SLPI have correspondingly increased and decreased expression, respectively, of transforming growth factor-beta 1 and cyclin D1 genes, relative to parental cells. SLPI selectively increased cyclin D1 gene expression, with the effect occurring in part at the level of promoter activity. Cellular SLPI levels negatively influenced the anti-proliferative and pro-apoptotic insulin-like growth factor-binding protein-3 expression. We also identified lysyl oxidase, a phenotypic inhibitor of the ras oncogenic pathway and a tumor suppressor, as SLPI-repressed gene, whose expression is up-regulated by transforming growth factor-beta1. Our results suggest that SLPI acts at the node(s) of at least three major interacting growth inhibitory pathways. Because expression of SLPI is generally high in epithelial cells exhibiting abnormal proliferation such as in carcinomas, SLPI may define a novel pathway by which cellular growth is modulated.

Base Sequence↗