Reduction in Ki-67 in benign breast tissue of high-risk women with the lignan secoisolariciresinol diglycoside

Preclinical and correlative studies suggest reduced breast cancer with higher lignan intake or blood levels. We conducted a pilot study of modulation of risk biomarkers for breast cancer in premenopausal women after administration of the plant lignan secoisolariciresinol given as the diglycoside (SDG). Eligibility criteria included regular menstrual cycles, no oral contraceptives, a >3-fold increase in 5-year risk, and baseline Ki-67 of ≥2% in areas of hyperplasia in breast tissue sampled by random periareolar fine-needle aspiration (RPFNA) during the follicular phase of the menstrual cycle. SDG (50 mg/d) was given for 12 months, followed by repeat RPFNA. The primary end point was change in Ki-67. Secondary end points included change in cytomorphology, mammographic breast density, serum bioavailable estradiol and testosterone insulin-like growth factor-I and IGF-binding protein-3, and plasma lignan levels. Forty-five of 49 eligible women completed the study with excellent compliance (median = 96%) and few serious side effects (4% grade 3). Median plasma enterolactone increased ∼9-fold, and total lignans increased 16-fold. Thirty-six (80%) of the 45 evaluable subjects showed a decrease in Ki-67, from a median of 4% (range, 2-16.8%) to 2% (range, 0-15.2%; P < 0.001, Wilcoxon signed rank test). A decrease from baseline in the proportion of women with atypical cytology (P = 0.035) was also observed. Based on favorable risk biomarker modulation and lack of adverse events, we are initiating a randomized trial of SDG versus placebo in premenopausal women.

Abstract 2053: Regulation of microRNA-10b by CCN5/WISP-2 in breast cancer: A novel mechanism of CCN5/WISP-2 mediated suppression of invasive front

Metastatic cells are a subset of primary tumor cells that have the skill to complete multi-step metastatic cascades, including dissemination, migration, extravasation, and eventual proliferation) at a discontinuous secondary site. Understanding the molecular biology of cancer metastasis may provide novel intervention strategies to control metastatic lesions, and/or to improve the quality of life for the patients with these advanced diseases. MicoRNAs are naturally occurring single-stranded RNA molecules that posttranscriptionally regulate the expression of target mRNA transcripts. Many of these target mRNA transcripts are involved in cell proliferation, differentiation and apoptosis, processes commonly altered during tumorigenesis. Recent findings have shown that microRNA-10b (miR-10b) is highly expressed in metastatic breast cancer cells and positively regulates cell migration and invasion. Expression of miR-10b is induced by Twist, a transcription factor that binds to putative promoter of miR-10b. We hypothesized that whether nullification of CCN5/WISP-2, an antiinvasive gene has any role in miR-10b expression. We found that nullification of CCN5/WISP-2 in ER-positive noninvasive breast tumor cell upregulates the miR-10b expression. Interestingly, we also found the upregulation of Twist by silencing CCN5/WISP-2. Collectively, we conclude that CCN5/WISP-2 may be a critical regulator of miR-10b expression through the HIF-1α-Twist signaling.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2053.

CCN5/WISP-2 expression in breast adenocarcinoma is associated with less frequent progression of the disease and suppresses the invasive phenotypes of tumor cells

Although previous in vitro studies predicted that CCN5/WISP-2 may act as an anti-invasive gene in breast cancer, the distribution pattern of CCN5 in breast cancer samples is conflicting. Thus, we systematically investigated the CCN5 expression profile in noninvasive and invasive breast tumor samples and its functional relevance in breast cancer progression. The studies showed that CCN5 expression is biphasic, such that in normal samples CCN5 expression is undetectable, whereas its expression is markedly increased in noninvasive breast lesions, including atypical ductal hyperplasia and ductal carcinoma in situ. Further, CCN5 mRNA and protein levels are significantly reduced as the cancer progresses from a noninvasive to invasive type. Additionally, we showed that CCN5 mRNA and protein level was almost undetectable in poorly differentiated cancers compared with the moderately or well-differentiated samples and its expression inversely correlated with lymph node positivity. The result was further supported by evaluating the RNA expression profile in microdissected sections using real-time PCR analysis. Therefore, our data suggest a protective function of CCN5 in noninvasive breast tumor cells. This hypothesis was further supported by our in vitro studies illuminating that CCN5 is a negative regulator of migration and invasion of breast cancer cells, and these events could be regulated by CCN5 through the modulation of the expression of genes essential for an invasive front. These include Snail-E-cadherin signaling and matrix metalloproteinase (MMP)-9 and MMP-2. Collectively, these studies suggest that the protective effect of CCN5 in breast cancer progression may have important therapeutic implications.

Reduction in proliferation with six months of letrozole in women on hormone replacement therapy

The objective of this study was to determine if 6 months of the aromatase inhibitor letrozole, administered to postmenopausal women taking a stable dose of hormone replacement remedy, would be safe and would modulate biomarkers of breast cancer risk. The intent was to reduce the proliferation marker Ki-67 while maintaining adequate systemic levels of estradiol so as to avoid perimenopausal symptoms. Postmenopausal women at high risk for development of breast cancer and taking a stable dose of estrogen or estrogen plus progestin were screened by random periareolar fine needle aspiration (RPFNA). To be eligible, the acquired breast epithelial cells had to be characterized as cytologic atypia or borderline atypia with > or =1,000 epithelial cells on the cytomorphology slide; plus > or =500 epithelial cells on a slide processed for Ki-67 immunocytochemistry. Forty-two women were enrolled in the one arm study and received 2.5 mg letrozole per day for 6 months, followed by repeat assessment of biomarkers. Ki-67 was reduced by a median relative value of 66%. There was no significant change in breast cell cytomorphology; ER weighted index score; serum estradiol, testosterone, or IGF-1:IGFBP-3 ratio; mammographic breast density, or frequency or severity of perimenopausal symptoms. Given the dramatic reduction in proliferation, the effect of letrozole on risk and response biomarkers should be explored further in a randomized, placebo-controlled Phase IIB breast cancer chemoprevention trial.

Detection of biomarker gene expression by real-time polymerase chain reaction using amplified ribonucleic acids from formalin-fixed random periareolar fine needle aspirates of human breast tissue

OBJECTIVE

To address the detection of breast cancer biomarker gene expression in formalin-fixed random periareolar fine needle aspiration (RPFNA) samples of benign breast tissue collected during breast cancer prevention trials by quantitative real-time polymerase chain reaction (qPCR).

STUDY DESIGN

Formalin-fixed breast epithelial cells collected by RPFNA and processed as thin layer preparations were isolated by laser capture microdissection (LCM). Ribonucleic acid (RNA) was extracted and amplified using a single round of T7-based linear amplification followed by quality assessment and biomarker assay using TaqMan chemistry.

RESULTS

More than 80% of RPFNA samples yielded RNA of sufficient quantity and quality for measurement of a panel of biomarker genes following a single round of linear amplification. RNA and protein expression for estrogen receptor alpha, as assessed by LCM/qPCR and immunohistochemistry, were correlated. Amplification plots were similar for cDNA standards and cDNA derived from RPFNA samples.

CONCLUSION

Assessment of gene expression using amplified RNA from microdissected formalin-fixed RPFNAs can increase the number of biomarkers used during breast cancer chemoprevention trials.

In vitro models for studying human uterine and placental macrophages

Human monocytes and macrophages, which are also called mononuclear phagocytes, represent a major arm of the innate immune system. These cells not only protect against infection but are also central to tissue remodeling and production of chemokines, cytokines, and growth factors. Tissue macrophages reside in the human placenta and uterine decidua throughout pregnancy, where they comprise part of the host defense network and facilitate placental and extraembryonic development. The purpose of this chapter is to describe methods for establishing useful models of human uteroplacental macrophages: (1) differentiated U937 myelomonocytic cells, (2) peripheral blood monocytes, (3) peripheral blood monocyte-derived macrophages, (4) decidual macrophages, and (5) placental macrophages.

Analysis of the soluble isoforms of HLA-G mRNAs and proteins

The human major histocompatibility complex (MHC) contains genes encoding the Human Leukocyte Antigens (HLA). Of these antigens, placental immunologists need study only the HLA class I molecules, because HLA class II expression is repressed in the fetal placental cells that are in direct contact with maternal blood and tissues containing maternal immune cells. The class I antigens are subdivided into two general categories. The class Ia antigens are highly polymorphic and are typified by HLA-A, -B, and -C; these are expressed by nearly all somatic cells and stimulate graft rejection when foreign to the host. By contrast, the HLA class Ib antigens, HLA-E, -F, and -G, have restricted expression, few variants, and appear rarely to be immunostimulatory. One class Ia antigen, HLA-C, and the three class Ib antigens are differentially expressed by trophoblast cell subpopulations. In order to understand immune privilege in the pregnant uterus and placenta, it is essential to study the unique structural and functional features of these four genes and their glycoprotein products. In this chapter, we focus on the first class Ib gene identified in human placentas, HLA-G, with emphasis on its two soluble isoforms, HLA-G5 and HLA-G6. We describe methods developed in our laboratory to distinguish mRNAs encoding HLA-G5 and HLA-G6, and antibody-based protocols for identification of the soluble isoforms.

Isolation and culture of term human trophoblast cells

Experimentation with most human cell types is restricted to the use of cell lines, and this limits our ability to extrapolate interpretations to the in vivo condition. However, in studying human trophoblast cells, we have a unique opportunity to obtain large quantities of readily available human tissue. In this chapter, we outline the methodology for purification of human trophoblast cells from term placentas. The procedures are based on enzymatic dissociation of villous placental tissue, followed by gradient centrifugation and immunomagnetic bead purification. Purity may be assessed by immunocytochemistry or flow cytometry using a number of markers to identify both cytotrophoblast cells and cellular contaminants. The resulting cytotrophoblast cell populations have excellent viability and purity, and may be subjected to long-term culture.

Placental cell expression of HLA-G2 isoforms is limited to the invasive trophoblast phenotype

The HLA-G message is alternatively spliced into multiple transcripts, two of which encode soluble isoforms. To initiate studies on the specific functions of the soluble isoforms, we produced soluble rHLA-G1 (rsG1) and rsG2 in human embryonic kidney 293 cells and characterized the proteins. Both isoforms were glycosylated and formed disulfide-bonded oligomers. Recombinant sG1 associated with beta(2)-microglobulin, whereas rsG2 did not. Mouse mAb generated to rsG1 (1-2C3), which identified exclusively sG1, and mAb generated to rsG2 (26-2H11), which identified both soluble and membrane G2 (m/sG2), were used for immunohistochemical isoform mapping studies on placental tissue sections. Soluble G1 protein was abundant in many subpopulations of trophoblast cells, whereas m/sG2 protein was present exclusively in extravillous cytotrophoblast cells. Although both isolated placental villous cytotrophoblast cells and chorion membrane extravillous cytotrophoblast cells contained mRNAs encoding sG1 and sG2, protein expression was as predicted from the immunostains with m/sG2 present only in the invasive trophoblast subpopulation. Analysis of function by Northern and Western blotting demonstrated that both rsG1 and rsG2 inhibit CD8alpha expression on PBMC without changing CD3delta expression or causing apoptotic cell death. Collectively, the studies indicate that: 1) both sG1 and m/sG2 are produced in placentas; 2) transcription and translation are linked for sG1, but not G2; 3) expression of G2 is exclusively associated with the invasive phenotype; and 4) the two isoforms of sG may promote semiallogeneic pregnancy by reducing expression of CD8, a molecule required for functional activation of CTL.

Toxicity of chlorpyrifos adsorbed on humic colloids to larval walleye (Stizostedion vitreum)

After application, organophosphorus insecticides (OPs) are often strongly adsorbed to soil constituents. Because of their relatively low water solubility, OPs may be transferred from field to stream adsorbed on suspended solids. However, we are not aware of research done to evaluate the bioavailability (i.e., toxicity) of OPs transported on suspended solids to fish. We conducted 48-h static toxicity tests to determine the toxicity of chlorpyrifos in aqueous solution and adsorbed on calcium-saturated humic acid (HA) to three larval stages of walleye (Stizostedion vitreum). Three concentrations of chlorpyrifos adsorbed on HA, a HA control, and a chlorpyrifos-only treatment were tested. Fish that survived the 48-h static toxicity tests were analyzed to determine total cholinesterase (ChE) activity. In general, survival of all larval stages of walleye exposed to chlorpyrifos-HA complexes was less than that of walleye exposed to HA controls and the chlorpyrifos-only treatment, which were not toxic to walleye. Cholinesterase inhibition of larval walleye exposed to chlorpyrifos-HA complexes was similar to the ChE inhibition observed in larval walleye exposed to chlorpyrifos in the aqueous phase. These laboratory experiments indicate potential toxicity of chlorpyrifos-soil complexes to larval fish.

Cell-specific expression of B lymphocyte (APRIL, BLyS)- and Th2 (CD30L/CD153)-promoting tumor necrosis factor superfamily ligands in human placentas

Apoptosis-inducing tumor necrosis factor (TNF) ligands and receptors have been reported in human placentas, but the expression patterns of family members lacking this function [a proliferation-inducing ligand (APRIL), B lymphocyte stimulator (BLyS), CD30L/CD153, CD40L/CD154, TNF-related activation-induced cytokine, CD27L/CD70, OX40L, activation-inducible TNF receptor ligand (AITRL)] are incompletely documented or unknown. We therefore investigated expression of these eight ligands and nine of their receptors (B cell maturation antigen, transmembrane activator and calcium-modulator and cyclophilin ligand-interactor, CD30, CD40, receptor activator of nuclear factor-kappaB, osteoprotegerin, CD27, OX40/CD134, AITR). Analysis by reverse transcriptase-polymerase chain reaction revealed mRNAs encoding only three of the ligands (APRIL, BLyS, CD30L/CD153). Immunoblots demonstrated all three proteins in first-trimester and term placentas, and immunohistochemical experiments showed that expression was cell-specific and gestation-related. Although mRNAs encoding receptors for the three expressed ligands were absent, those encoding receptors for all of the unexpressed ligands were detectable. Collectively, the results are consistent with the postulate that nonapoptosis-inducing, placenta-derived TNF superfamily cytokines contribute to the T helper cell type 2 bias required for successful pregnancy. Patterns of placental expression of receptors suggest bidirectional maternal-fetal cytokine communication.

B7 family molecules are favorably positioned at the human maternal-fetal interface

The human placenta utilizes both active and passive mechanisms to evade rejection by the maternal immune system. We investigated the pattern of expression of the B7 family of immunomodulatory molecules B7-H1 (PD-L1), B7-2 (CD86), and B7-1 (CD80) at the term maternal-fetal interface. Northern blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses showed that B7-H1 mRNA is abundant in term placenta and that cytotrophoblasts are sources of this message. Immunohistochemistry demonstrated that B7-H1 is constitutively expressed by the syncytiotrophoblast and by extravillous cytotrophoblasts, both of which are juxtaposed to maternal blood and tissue. By contrast, placental stromal cells, including macrophages, lacked the protein. Expression of B7-H1 protein was low in first-trimester placenta compared to second- and third-trimester tissue (P < 0.05) and was enhanced in cultured cytotrophoblasts by treatment with either interferon-gamma or epidermal growth factor (P < 0.05), suggesting that one or both of these mediators regulates B7-H1 expression in the placenta. RT-PCR and immunofluorescence analysis of term placental tissue revealed different patterns of expression of the immunostimulatory protein, B7-2. In contrast to B7-H1, B7-2 mRNA and protein were absent in cytotrophoblast cells but present in maternal macrophages and some fetal macrophages. The B7-1 mRNA and protein were absent at the maternal-fetal interface. These studies document expression of the B7 family proteins at the maternal-fetal interface and demonstrate that B7-H1 is positioned such that it could facilitate protection of fetal cells against activated maternal leukocytes. Conversely, B7-2 was absent on trophoblasts and was appropriately localized to fetal and maternal macrophages, which may participate in antigen presentation.

Environmental, biological, and methodological factors affecting cholinesterase activity in walleye (Stizostedion vitreum)

Organophosphorus (OP) insecticides have high acute toxicity toward many nontarget vertebrate and invertebrate organisms, but direct measurement of OPs in environmental samples is difficult because their concentrations may fall below detection limits within hours to days after entering aquatic ecosystems. Because OPs exert toxicity through cholinesterase (ChE) inhibition, which may persist for up to several weeks, ChE inhibition has been widely used in aquatic ecosystems as a biomarker for OP exposure in aquatic organisms. However, the biological, environmental, and methodological factors affecting ChE activity have not been well documented and must be considered and understood before ChE activity can be used as a dependable indicator of OP exposure to aquatic organisms. This study examined the influence of water temperature, size of larval and juvenile walleye (Stizostedion vitreum), stress, long-term storage, postmortem changes, and methods of euthanasia on ChE activity. Water temperature (17.2, 20.9, and 24.6 degrees C), stress, long-term storage (up to 180 days), postmortem changes, and method of euthanasia had no effect on ChE activity of walleye. There was a strong positive correlation (r = 0.87) between whole body ChE activity and total length (7.2-17.9 mm) for larval walleye, but a negative correlation between brain ChE activity and total length (59-164 mm) for juvenile walleye (r = 0.75). Because size, age, and development may affect ChE activity, fish of similar size should be used when evaluating the effects of ChE inhibitors. If fish of similar size are not available, it is recommended that relations between size, age, and development be understood so estimates of variation in ChE activity can be made.

B7 family molecules: novel immunomodulators at the maternal-fetal interface

The placenta utilizes both active and passive mechanisms to evade rejection by the maternal immune system. Recently, the mRNA for two newly cloned members of the B7 family of immunomodulatory cell-associated proteins have been identified in the human term placenta. In this article, we review the current knowledge of the B7 family member B7-H1, and discuss how it may participate in modulation of the maternal immune system at the maternal-fetal interface. B7-H1 has been found to possess immunostimulatory or immunoinhibitory properties, and immunohistological examination of first trimester and term placenta has revealed that this protein is abundant in the placenta. B7-H1 is highly expressed by both the syncytiotrophoblast and extravillous cytotrophoblast, both of which lie in direct contact with maternal blood and tissue. Further, treatment of the choriocarcinoma cell line, JEG-3, with recombinant human interferon (IFN)-gamma resulted in a dose-dependent increase in the abundance of the message for B7-H1, suggesting that IFN-gamma could regulate expression of B7-H1 by the trophoblast. These studies document that the positioning of B7-H1 at the maternal-fetal interface is such that it could participate in suppression of activated maternal leukocytes.

Death-inducing tumour necrosis factor (TNF) superfamily ligands and receptors are transcribed in human placentae, cytotrophoblasts, placental macrophages and placental cell lines

Human placentae and two of the cell types in placentae (cytotrophoblasts and macrophages) were examined by RT-PCR for transcripts of the eight TNF superfamily ligands known to induce death of activated immune cells, tumour cells, and virus-infected cells (TNFalpha, LT alpha, LT beta, FasL, TRAIL, TWEAK, LIGHT, 4-1BBL). Transcripts for all ligands were detected in term placenta but LT alpha and 4-1BBL were not detected in first trimester placenta. Although term cytotrophoblasts contained mRNAs specific for TNF alpha, LT alpha, TWEAK, and 4-1BBL, messages encoding LT beta, FasL, TRAIL, and LIGHT were absent. In term placental macrophages, messages for all ligands except 4-1BBL were present. Transcripts for the 14 receptors to which the ligands bind, six of which contain death-domains (TNFR1, Fas, DR3, DR4, DR5, DR6), were also identified using RT-PCR. Term and first trimester placentae contained transcripts for all receptors except 4-1BB. Although term cytotrophoblasts lacked receptor mRNA encoding 4-1BB and OPG, term placental macrophages lacked DcR1 and OPG. Detection of nearly all the death-inducing TNF superfamily ligands and their receptors in human placentae implies that these powerful cytokines contribute to programmed or activated cell death in this organ.

TRAIL (Apo-2L) and TRAIL Receptors in Human Placentas: Implications for Immune Privilege

Mechanisms accounting for protection of the fetal semiallograft from maternal immune cells remain incompletely understood. In other contexts, interactions between TRAIL (TNF-related apoptosis-inducing ligand/Apo-2L) and its receptors kill activated lymphocytes. The purpose of this study was therefore to investigate the potential of the TRAIL/TRAIL-R system to protect the placenta against immune cell attack. Analysis by Northern blotting demonstrated mRNAs encoding TRAIL as well as the four TRAIL receptors (DR4, DR5, DcR1/TRID, DcR2/TRUNDD) in human placentas. Immunohistochemical experiments demonstrated that TRAIL protein is prominent in syncytiotrophoblast, an uninterrupted placental cell layer that is continuously exposed to maternal blood, as well as in macrophage-like placental mesenchymal cells (Hofbauer cells). Studies on cell lines representing trophoblasts (Jar, JEG-3 cells) and macrophages (U937, THP-1 cells) showed that both lineages contained TRAIL mRNA and that steady state levels of transcripts were increased 2- to 11-fold by IFN-γ. By contrast, cell lineage-specific differences were observed in expression of the TRAIL-R genes. Although all four lines contained mRNA encoding the apoptosis-inducing DR5 receptor, only trophoblast cells contained mRNA encoding the DcR1 decoy receptor and only macrophages contained DcR2 decoy receptor transcripts. DR4 mRNA was present only in THP-1 cells and was the only TRAIL-R transcript increased by IFN-γ. Cytotoxicity assays revealed that the two trophoblast cell lines were resistant, whereas the two macrophage lines were partially susceptible to killing by rTRAIL. Collectively, the results are consistent with a role for the TRAIL/TRAIL-R system in the establishment of placental immune privilege.

TRAIL (Apo-2L) and TRAIL receptors in human placentas: implications for immune privilege

Mechanisms accounting for protection of the fetal semiallograft from maternal immune cells remain incompletely understood. In other contexts, interactions between TRAIL (TNF-related apoptosis-inducing ligand/Apo-2L) and its receptors kill activated lymphocytes. The purpose of this study was therefore to investigate the potential of the TRAIL/TRAIL-R system to protect the placenta against immune cell attack. Analysis by Northern blotting demonstrated mRNAs encoding TRAIL as well as the four TRAIL receptors (DR4, DR5, DcR1/TRID, DcR2/TRUNDD) in human placentas. Immunohistochemical experiments demonstrated that TRAIL protein is prominent in syncytiotrophoblast, an uninterrupted placental cell layer that is continuously exposed to maternal blood, as well as in macrophage-like placental mesenchymal cells (Hofbauer cells). Studies on cell lines representing trophoblasts (Jar, JEG-3 cells) and macrophages (U937, THP-1 cells) showed that both lineages contained TRAIL mRNA and that steady state levels of transcripts were increased 2- to 11-fold by IFN-gamma. By contrast, cell lineage-specific differences were observed in expression of the TRAIL-R genes. Although all four lines contained mRNA encoding the apoptosis-inducing DR5 receptor, only trophoblast cells contained mRNA encoding the DcR1 decoy receptor and only macrophages contained DcR2 decoy receptor transcripts. DR4 mRNA was present only in THP-1 cells and was the only TRAIL-R transcript increased by IFN-gamma. Cytotoxicity assays revealed that the two trophoblast cell lines were resistant, whereas the two macrophage lines were partially susceptible to killing by rTRAIL. Collectively, the results are consistent with a role for the TRAIL/TRAIL-R system in the establishment of placental immune privilege.

Trophoblastic cell lines generated from tumour necrosis factor receptor-deficient mice reveal specific functions for the two tumour necrosis factor receptors

In mice and humans, expression of the tumour necrosis factor receptor-1 (TNF-R1) gene in placental trophoblast cells is constitutive whereas expression of the TNF-R2 gene is developmentally programmed. In order to study the individual functions of TNF-R1 and -R2 in this lineage, cell lines were generated from placental explants of homozygous matings of gestation day 10 outbred mice (Swiss-Webster), TNF-R1-deficient (TNF-R1-/-) and TNF-R2-/- transgenic mice as well as the background strain for the TNF-R2-/- mice (WT, C57BL/6x129). All of the cells exhibited trophoblast markers; they contained cytokeratin intermediate filaments, expressed alkaline phosphatase activity and displayed transferrin receptors, but were negative for vimentin filaments and the macrophage marker, F4/80. Analysis of DNA by polymerase chain reaction demonstrated the expected TNF-R genotype in each line. In experiments testing the effects of recombinant mouse TNF-alpha (rmTNF-alpha) on viability and proliferation of the cell lines, rmTNF-alpha modestly but dose-dependently inhibited the growth of WT and TNF-R2-/- cells while having no effect on TNF-R1-/- cells. Actinomycin D-treated WT and, to a lesser extent, TNF-R2-/- cells, were more sensitive to growth inhibition than untreated cells whereas TNF-R1-/- cell responses remained unchanged. These data indicated that rmTNF-alpha inhibits growth of trophoblastic cells through TNF-R1 and that newly synthesized protein(s) provide partial protection against toxicity. In contrast to the receptor species-specific effects on cell growth exerted by rmTNF-alpha, both TNF-R mediated inhibition of alkaline phosphatase activity. Collectively, the observations support the postulate that receptor expression is the key factor which determines the nature and extent of TNF-alpha effects on trophoblast cell growth and function.

The mouse macrophage activation-associated marker protein, p71/73, is an inducible prostaglandin endoperoxide synthase (cyclooxygenase)

The inducible protein p71/73 marks the response of mouse macrophages to one of several stimuli (e.g., bacterial lipopolysaccharide or poly I:C) that trigger the expression of cytolytic activity when these cells have previously been primed for tumor cell killing by interferon-gamma (IFN-gamma). The results reported here identify this marker protein as the inducible prostaglandin endoperoxide synthase (PES), TIS10/PES-2. Identification was based on four findings: (1) p71/73, like the TIS10/PES-2 protein, was associated with cellular membranes; (2) the sequence of amino acids in the NH2 terminus of both p71 and p73 was 96% identical to the predicted NH2-terminal sequence of the TIS10/PES-2 protein; (3) a polyclonal antiserum raised against the COOH-terminal region of the TIS10/PES-2 gene product recognized p71/73 in immunoblots; and (4) dexamethasone, which blocks induction of TIS10/PES-2 expression, inhibited the induction of both p71/73 synthesis and tumoricidal activity in macrophage. Several regulatory roles for this protein in the activation process are possible.

Activation-associated marker proteins: peptide mapping and their expression in macrophage cell lines

The activation-associated markers, p47b and p71/73, have been recognized as minor proteins in peritoneal and bone marrow culture-derived macrophages activated for tumor cell killing. Proteins with identical characteristics of migration on 2-dimensional gels and comparable Cleveland peptide maps are described here in macrophage cell lines that could be activated for tumor cell killing (J774A.1, RAW 264, UNC-2). Macrophage cell lines that could not be activated (P388D1 and PU5-1.8) did not express the markers. The expression of these markers in activatable macrophage cell lines strengthens their association with the activation process and provides a bulk source of the proteins for purification studies.

Loss of 4.5S RNA induces the heat shock response and lambda prophage in Escherichia coli

During depletion of 4.5S RNA, cells of Escherichia coli displayed a heat shock response that was simultaneous with the first detectable effect on ribosome function and before major effects on cell growth. Either 4.5S RNA is involved directly in regulating the heat shock response, or this particular impairment of protein synthesis uniquely induces the heat shock response. Several hours later, lambda prophage was induced and the cells lysed.

Levels of DNA topoisomerases, single-stranded-DNA-binding protein, and DNA polymerase I in rho+ and rho-15 strains of Escherichia coli

The Escherichia coli rho-15 mutant, which is highly defective in transcription termination, was examined to see whether its reduced DNA superhelicity could be explained by altered expression of proteins that may affect DNA structure. Levels of DNA gyrase and topoisomerase I were normal; levels of single-stranded-DNA-binding protein, DNA polymerase I, and a protein tentatively identified as Lon were significantly altered.

Genomically linked cellular protein databases derived from two-dimensional polyacrylamide gel electrophoresis

In its most useful form a cellular protein database should be genomically based, because it is the genome which determines both the total number of proteins a cell can make and the particular ones that will be made under any given condition. Such a database should trace each protein back to its structural gene, and should account for every structural gene of a cell. Recent advances in molecular biology greatly facilitate the construction of such gene-protein databases. The mapping of genes of unidentified proteins resolved from total cell extracts on two-dimensional gels can now be accomplished by largely biochemical methods, without the necessity of isolating mutants or performing genetic crosses. Other techniques permit one to search gels for the product of any newly discovered gene (or open reading frame) suspected of encoding a protein. Consequently, gene-protein indices can be built independently and simultaneously from either direction--deducing the genetic map from the protein pattern, or finding the protein pattern from information encoded in the genome. A database of this sort is being constructed for the bacterium, Escherichia coli. Given the current pace of DNA nucleotide sequencing, the development of total gene-protein indices for a variety of cells can be anticipated in the near future.