Beyond estrogen: advances in tissue selective estrogen complexes and selective estrogen receptor modulators.

Selective estrogen receptor modulators (SERMs) are synthetic non-steroidal agents which have variable estrogen agonist and antagonist activities in different target tissues. Tamoxifen is an anti-estrogen in the breast used for treatment and prevention of breast cancer, with estrogen agonist activity in the uterus. Raloxifene prevents and treats osteoporosis and prevents breast cancer, and can be safely combined with vaginal but not systemic estrogen. The tissue selective estrogen complex combines conjugated equine estrogens (CEE) with the SERM bazedoxifene (BZA). The five Selective Estrogen Menopause and Response to Therapy studies, with up to 2 years of data, demonstrated that CEE/BZA 0.45 mg/BZA 20 mg improved vasomotor symptoms and vulvovaginal atrophy, prevented bone loss, and was neutral on breast tenderness, breast density, with breast cancer incidence similar to placebo. Protection against estrogen-induced endometrial hyperplasia and cancer was found, with similar amenorrhea rates to placebo. Ospemifene is approved to treat dyspareunia, with potential benefits on bone and the breast, while lasofoxifene is being developed to treat resistant estrogen receptor-positive breast cancer in women. Estetrol is an estrogen synthesized exclusively during pregnancy by the human fetal liver and initially considered a weak estrogen, but it appears to have dual weak estrogenic/anti-estrogenic features.

Molecular targeting of CSN5 in human hepatocellular carcinoma: a mechanism of therapeutic response.

Development of targeted therapy for hepatocellular carcinoma (HCC) remains a major challenge. We have recently identified an elevated expression of the fifth subunit of COP9 signalosome (CSN5) in early HCC as compared with dysplastic stage. In the present study, we explored the possibility of CSN5 being a potential therapeutic target for HCC. Our results show that CSN5 knockdown by small-interfering (si) RNA caused a strong induction of apoptosis and inhibition of cell-cycle progression in HCC cells in vitro. The down-regulation of CSN5 was sufficient to interfere with CSN function as evidenced by the accumulation of neddylated Cullin 1 and changes in the protein levels of CSN-controlled substrates SKP2, p53, p27 and nuclear factor-κB, albeit to a different degree depending on the HCC cell line, which could account for the CSN5 knockdown phenotype. The transcriptomic analysis of CSN5 knockdown signature showed that the anti-proliferative effect was driven by a common subset of molecular alterations including down-regulation of cyclin-dependent kinase 6 (CDK6) and integrin ß1 (ITGB1), which were functionally interconnected with key oncogenic regulators MYC and TGFß1 involved in the control of proliferation, apoptotic cell death and HCC progression. Consistent with microarray analysis, western blotting revealed that CSN5 depletion increased phosphorylation of Smad 2/3, key mediators of TGFß1 signaling, decreased the protein levels of ITGB1, CDK6 and cyclin D1 and caused reduced expression of anti-apoptotic Bcl-2, while elevating the levels of pro-apoptotic Bak. A chemically modified variant of CSN5 siRNA was then selected for in vivo application based on the growth inhibitory effect and minimal induction of unwanted immune response. Systemic delivery of the CSN5 3/8 variant by stable-nucleic-acid-lipid particles significantly suppressed the tumor growth in Huh7-luc+ orthotopic xenograft model. Taken together, these results indicate that CSN5 has a pivotal role in HCC pathogenesis and maybe an attractive molecular target for systemic HCC therapy.

Dual functions of E2F-1 in a transgenic mouse model of liver carcinogenesis.

Deregulation of E2F transcriptional control has been implicated in oncogenic transformation. Consistent with this idea, we recently demonstrated that during hepatocarcinogenesis in c-myc/TGFalpha double transgenic mice, there is increased expression of E2F-1 and E2F-2, as well as induction of putative E2F target genes. Therefore, we generated transgenic mice expressing E2F-1 under the control of the albumin enhancer/promoter to test the hypothesis that E2F family members may contribute to liver tumor development. Overexpression of E2F-1 resulted in mild but persistent increases in cell proliferation and death during postnatal liver growth, and no increases in hepatic regenerative growth in response to partial hepatectomy. Nevertheless, from 2 months postnatally E2F-1 transgenic mice exhibited prominent hepatic histological abnormalities including preneoplastic foci adjacent to portal tracts and pericentral large cell dysplasia. From 6 to 8 months onward, there was an abrupt increase in the number of neoplastic nodules ('adenomas') with 100% incidence by 10 months. Some adenomas showed evidence of malignant transformation, and two of six mice killed at 12 months showed trabecular hepatocellular carcinoma. Endogenous c-myc was up-regulated in the early stages of E2F-1 hepatocarcinogenesis, whereas p53 was overexpressed in the tumors, suggesting that both E2F-1-mediated proliferation and apoptosis are operative but at different stages of hepatocarcinogenesis. In conclusion, E2F-1 overexpression in the liver causes dysplasia and tumors and suggests a cooperation between E2F-1 and c-myc oncogenes during liver oncogenesis.

HGF-mediated apoptosis via p53/bax-independent pathway activating JNK1.

Current studies have indicated both positive and negative roles for the hepatocyte growth factor (HGF)/c-met receptor signaling system in tumor development. Recently, we have shown that HGF has the capacity to induce both growth inhibition and programmed cell death in aflatoxin-transformed (AFLB8) rat liver epithelial cells. Using the same cell line, we have now investigated a potential mechanism for HGF-induced apoptosis. Immunoblot analysis of bcl-2 gene family member (bax, bcl-2, bclX-s/l) expression showed no correlation with HGF treatment, suggesting that HGF-mediated apoptosis is bax independent. Following HGF treatment retinoblastoma protein (pRB) was present in the hypophosphorylated state. HGF treatment increased cyclin A, cyclin G1 and nuclear transcriptional factor (NFkappaB) protein expression. However, electrophoretic mobility shift analysis showed that NFkappaB activity decreased with HGF treatment. Under these apoptotic conditions, c-Jun N-terminal kinase (JNK1) and extracellular signal-regulated kinase (ERK2) were activated with lower level activation of ERK2, while no involvement of phosphatidylinositol-3 kinase was observed. Epidermal growth factor (EGF) was not protective, and actually induced cells to undergo apoptosis to a level similar to that of HGF alone or EGF/HGF in combination. These results suggest the possibility of cross-talk between HGF/c-met and EGF/EGFR signaling pathways, and the involvement of JNK1 induction in HGF-mediated apoptotic cell death.

Growth inhibition and induction of apoptosis by HGF in transformed rat liver epithelial cells.

Recently we demonstrated in a transgenic mouse model that hepatocyte growth factor (HGF) inhibits c-myc dependent hepatocarcinogenesis. The inhibitory effects of HGF in carcinogenesis were further characterized using a series of rat liver epithelial (RLE) cell lines which were transformed in vitro with either aflatoxin or oncogenes, or spontaneously. HGF caused a cytostatic effect and enhanced cell motility in spontaneously and aflatoxin-transformed cells. In normal RLE cells HGF was slightly stimulatory and did not induce scattering. The HGF receptor was tyrosine phosphorylated in all cell lines, indicating that it is functionally active and capable of signaling events. In the aflatoxin transformed cells HGF also induced apoptosis, associated with constitutive c-myc expression and 1 Kb bax-alpha transcripts. These findings indicate that transformed RLE cell lines may provide a useful model to further examine the mechanism(s) by which HGF and its receptor modulate neoplastic development.

Aberrant expression and regulation of hepatic epidermal growth factor receptor in a c-myc transgenic mouse model.

In an attempt to elucidate the mechanism by which c-myc and transforming growth factor-alpha (TGF-alpha) cooperate in hepatocyte tumor development, we have analyzed signaling by the epidermal growth factor (EGF) receptor and the consequent regulation of receptor number in transgenic mice bearing the c-myc transgene under the control of the albumin enhancer/promoter. 125I-EGF binding and Scatchard analysis indicated a single class of high affinity receptors with the total number of binding sites of 1.2 X 10(4) +/- 600 and 2.5 X 10(5) +/- 1000 sites/cell in the normal and c-myc hepatocytes in primary culture, respectively. After 72 h of EGF exposure in culture, the number of detectable EGF receptors on the cell surface of the c-myc hepatocytes was not reduced, whereas the number of EGF receptors on normal hepatocytes was reduced to 32% that of untreated hepatocytes. Nuclear run-on experiments done with nuclei isolated from intact livers demonstrated that transcription of the EGF receptor was 4.9-fold higher in c-myc mice. Increased levels of the transcriptional factor SP1 in the c-myc hepatocytes in vivo and in primary culture, suggest a mechanism for the increased transcription of the EGF receptor. c-myc also increases the expression of TGF-alpha; a consequent increase in tyrosine phosphorylation is also detected in vivo. Thus, the increased number of EGF receptors in c-myc expressing hepatocytes, even after prolonged exposure to EGF, or TGF-alpha in vivo, may allow greater triggering of the EGF receptor signaling cascade.

Protein alterations associated with gene amplification in cultured human and rodent cells.

Genomic stability was investigated in Chinese hamster ovary (CHO) and human hepatocellular carcinoma HepG2 cells selected for growth in the presence of cytotoxic concentrations of N-(phosphonacetyl-L-asparate) (PALA). In CHO cells selected with 9 x LD50 PALA the carbamyl p-synthetase, aspartate transcarbamylase and dihydroorotase (CAD) gene complex was amplified two-fold while in HepG2 cells selected at comparable PALA concentrations a 7- to 10-fold increase in the CAD gene was observed. Concomitant with amplification of the CAD gene were increases in CAD mRNA and protein expression in both CHO and HepG2 cells. In long-term cultures of HepG2 cells the CAD gene underwent spontaneous amplification (5-fold) in the absence of PALA treatment with increasing passage number. In an attempt to define proteins and/or family of proteins that may either directly or indirectly influence DNA amplification potential through a mechanism of enhanced genomic instability, immobilized pH gradient-two-dimensional polyacrylamide gel electrophoresis (IPG 2-D PAGE) analysis of silver-stained nuclear cytoplasmic polypeptides concomitant with PALA resistance and CAD amplification was performed. Analysis of silver-stained polypeptides from 3 x LD50 PALA-selected CHO and HepG2 cells revealed no significant alterations in polypeptide expression. In CHO cells selected at 5 x and 7 x PALA LD50, and HepG2 cells selected at 5 x and 9 x PALA LD50, one subset of 4-8 polypeptides (pl: pI 7.2-7.6/36-38 kDa) were increased 2- to 3-fold in both 5 x and 7 x- and 5 x and 9 x LD50 PALA-selected CHO and HepG2, respectively, while five relatively neutral-to-basic, low M(r) polypeptides (p2: 18/7.30; p3: 16/7.00; p4: 14/7.00; p5: 14/7.40; and p6: 13.5/7.00) were markedly increased in CHO cells selected at 7 x LD50 PALA. In addition to these PALA-associated increases, four polypeptides (p7a: pI 6.50/40 kDa; p7b: 6.55/40; p7c: 6.60/40; and p7d: 6.65/40) were significantly increased in high-passage (p159) HepG2 cells undergoing spontaneous CAD gene amplification in the absence of PALA exposure. In CHO cells, polypeptides p7 a, b, d were increased while the expression of p7c (pI 6.60/40 kDa) was unaltered in 7 x LD50-treated CHO cells. Although neither the identity nor biological function of polypeptides 1-7 is known, a proposed mechanism involving interaction with certain growth regulatory proteins such as p53 for mediating genomic instability is given.

Protocol for releasing Novacor left ventricular assist system patients out-of-hospital.

Between September 1984 and April 1995, the Novacor left ventricular assist system (LVAS) has provided more than 13,000 days of mechanical circulatory support to cardiac transplant candidates in the United States and Europe. The duration of support of these 312 patients has ranged between 1 and 370 days, with an average support of 40 days, including use of the console based system and the wearable system. Of this group, 21% have been supported for more than 60 days, with an average support of 118 days. We have seen that patients who have been supported for more than 30 days have recovered from the effects of LVAS implant surgery and have shown a potential for rehabilitation from morbid congestive heart failure. Few changes to the pump settings or the medical orders have been needed after the third postoperative week. The reliability of the LVAS and the degree to which patients can be rehabilitated suggest that restricting patients to a hospital environment is unnecessary. In addition, the increasing wait for a donor heart, the quality of life that can be achieved, and the high cost of inpatient care make it desirable to discharge patients from the hospital and allow them to await a donor heart in a more home-like setting.

Alterations in the heme biosynthetic pathway from the III-V semiconductor metal, indium arsenide (InAs).

The effects of indium and arsenic on the heme biosynthetic pathway have been well documented but the effects of indium arsenide (InAs), the next possible generation of the III-V semiconductors, are unknown. Male Syrian golden hamsters were given s.c. injections of sodium arsenite (As3+), indium chloride (In3+) or indium arsenide (InAs). Erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity was inhibited in all exposure groups, while hepatic ALAD activity was not significantly changed. In contrast, the activity of renal ALAD was found to be statistically decreased by As3+ at 10 days, but increased at 30 days, while In3+ and InAs inhibited this enzyme activity at all time points. In vitro studies showed that hepatic ALAD activity was more sensitive to In3+ than As3+, suggesting that the effects of InAs in vivo on this enzyme are due primarily to the In rather than the As moiety. Studies of urinary porphyrin excretion patterns in animals treated with InAs showed marked, early 2-4-fold increase in the excretion of the penta-, hexa- and heptacarboxyl porphyrin at 1-5 days which continued through day 30 of the study. In contrast, there was a slow and steady rise in the excretion of coproporphyrin I and III which reached a maximum at day 30. The results of these studies indicate that both the In and As moieties of InAs are biologically active following InAs exposure and that the enzymes in the heme pathway, such as ALAD, may have great utility as markers of exposure/toxicity for these agents.

Biological indicators for monitoring exposure/toxicity from III-V semiconductors.

These studies were conducted to assess alterations in renal tubule cell gene expression following in vivo exposure to the semiconductor elements indium (In), arsenic (As) or indium arsenide (InAs). Alterations in proximal tubule cell gene expression were monitored at similar tissue concentrations of In or As at various time-points following single subcutaneous (sc) injections of In, As or InAs at 0, 10 and 30 days (In: 1.5 mg/kg; As, 3 mg/kg or 0.3 mg/k; and InAs: 1000 mg/kg). Protein synthesis as monitored by incorporation of 35S methionine was not statistically increased over the 30-day period following sc injection of As, In or InAs relative to controls. Two dimensional--SDS/polyacrylamide gel electrophoresis showed that exposure to InAs stimulated the synthesis of a number of proteins with molecular masses of < 10, 18, 28, 32, 38, 42, 58, 70, 98 KDa. Exposure to As produced an increase in the expression of thirteen gene products. Indium produced similar changes at the 10-day time-point, but increased tissue accumulation of this element at 30 days markedly suppressed the stress protein response. These data indicate that induction of these specific gene expression patterns may be useful as early indicators for assessing exposure to InAs, or inorganic As, while suppression of these responses by In suggests a compromise in this basic protective mechanism.

Implications of lead binding proteins for risk assessment of lead exposure.

Lead-binding proteins have previously been isolated from rat and human target tissues. These molecules have shown to possess molecular masses in the general range of 10,000-30,000 daltons. The proteins are acidic in nature and rich in aspartic and glutamic amino acid residues. The molecules in rodents appear to play several important roles in mediating the low dose toxicity of lead in the kidney and brain. Preliminary studies presented in this report indicate that monkeys also possess similar proteins in the kidney and brain, thus providing a biochemical "bridge" in a non-human primate between rodent models and humans. Further, the excretion of these molecules into the urine of rodents increases with lead exposure, suggesting that may also prove useful as biomarkers of lead exposure in humans and monkeys once the dose-range and mechanism(s) of this phenomenon are further defined. Such studies should provide valuable risk assessment information for determining why individuals vary in their susceptibility to lead toxicity.

Cancer risks for humans from exposure to the semiconductor metals.

Of the semiconductor metals, only arsenic has been extensively studied as a human carcinogen and systemic toxicant. Recent studies have shown, however, that gallium, arsenic, and indium are capable of producing marked alterations in cellular gene products. After acute in vivo administration indium and thallium have been shown to produce decreases in the activity of some drug-metabolizing enzymes dependent on cytochrome P-450; therefore these metals would be capable of interfering with the metabolism of organic carcinogens. Selenium is essential for the activity of the enzyme glutathione peroxidase, which modulates the active intermediates generated by drug-metabolizing enzyme systems. Germanium produces toxicity in a number of organ systems. Antimony produces lung and circulatory system effects. Overall, available data suggest that these metals or metalloids are capable of biologically altering several cellular defense mechanisms involved in the carcinogenic process and that further studies are needed to determine the associated risks.

Estrogen and progesterone regulation of proliferation, migration, and loss in different target cells of rabbit uterine epithelium.

We have explored the possibility that estrogens and progesterone could have different target uterine cell populations according to their cell cycle stage and localization in glands vs. lumen. Experiments were carried out in which rabbits were injected with [3H]thymidine for 3 days to label nuclei of dividing cells, then either 17 beta-estradiol, progesterone, or vehicle were administered. 17 beta-Estradiol induced a decrease in the percentage of cells with labeled nuclei or labeling index of either luminal or glandular epithelium. Since this steroid has been shown to have a significant proliferative effect on glands, the data suggest that its effect is exerted on unlabeled quiescent cells, which are then recruited into the cell cycle. Progesterone, on the other hand, was found to induce a significant increase in labeling index of both luminal and glandular epithelium. Therefore, it is concluded that dividing cells are a target for this hormone. Analysis of the number of nuclear grains according to cell location in luminal vs. glandular epithelia and the effect of hormone administration confirmed that each ovarian hormone acts on different target cell populations. Short and long term administration of estrogens resulted in a larger internal circumference of the uterus due to an increase in the number of luminal cells, whereas the number of glands and glandular cells per section did not appear to change. These findings, in combination with previous research, suggest that endometrial gland cells migrate towards the lumen and estrogen administration decreases the rate of cell loss in the luminal epithelium. The concept of cell migration is supported by experiments in which single administration of [3H]thymidine to rabbits was followed by determination at different times of the geographical distribution of cells with labeled nuclei. There was observed, as a function of time, a decrease in the number of labeled cells in the bottom of the glands with a concomitant increase in the same parameter in the upper part of the glands and luminal epithelia. Estradiol administration changed these kinetics.

Intrauterine ethanol-induced termination of pregnancy in cynomolgus monkeys (Macaca fascicularis).

The effectiveness of locally applied ethanol in terminating early pregnancy in cynomolgus monkeys was studied. In a randomized trial ethanol (70 per cent, 1 ml.) or saline (0.9 per cent, 1 ml.) was injected extra-amniotically through a sterile blunt-end needdle inserted through the cervix into the uterine cavity. Six of seven monkeys receiving ethanol showed vaginal bleeding beginning one or two days after treatment. With the one failure, alcohol leakage occurred from the Luer-lock needle joint at the time of injection and the amount entering the uterus was unknown. No animal receiving saline showed any vaginal bleeding. The six monkeys showing vaginal bleeding were found to have nonenlarged or subnormally enlarged uteri one month after treatment. All monkeys subsequently resumed menstrual cycles within one year. Three monkeys became pregnant and were delivered at term of healthy offspring. Histologic evaluation of uteri from ethanol-treated monkeys revealed necrosis of decidua and, to a lesser degree, of the placenta one day after injection. The high efficacy of 70 per cent ethanol in inducing endometrial sloughing and the documentation of normal subsequent pregnancies in 50 per cent of treated monkeys make this technique worthy of consideration as a menstrual induction agent in women.

Efficacy of various locally applied chemicals as contragestational agents in rats.

PIP: Test agents were selected because of previous evidence of contragestationaal activity when administered systemically or because of known local effects which would be likely to cause endometrial changes having an adverse effect on pregnancy. A group of virgin female Sprague-Dawley rats were treated on Day 3 of pregnancy (preimplantation) and another group on Day 7 of pregnancy (postimplantation). Injections of .05 ml were made directly into the lumen of each uterine horn. Sodium chloride .9% was used on 1 side and the test agent on the other side. Implantation sites were counted before injections on Day 7. The number of corpora lutea indicated the expected number of conceptions of those injected on Day 3. On Day 15 rats were sacrificed and corpora lutea, viable conceptuses, and absorption sites were counted. Ethanol at 100, 80, 70, and 63% was a highly effective contragestational agent when given on Day 3. Formaldehyde 7-.5% was also highly effective when given on Day 3 but higher concentrations produced maternal toxicity and death. Silver nitrate, iodine, rivanol, cyclizine, urea, and 17beta-bromoacetoxy-19-nortestosterone produced no maternal toxicity but were all effective in reducing the number of viable fetuses. Prostaglandin (PGF2alpha), indomethacin, and ergonovine had no observable effect on preimplantation embryos. Methotrexate reduced survival when injected on Day 3 and more so when given on Day 7 but a systemic toxic effect was also noted. When injected on Day 7 all of the compounds except methotrexate were markedly less effective. Survival of fetuses in the control horns varied from 50% to 100%. Ethanol produced sloughing and necrosis but the endometrium appeared to be normal after 96 hours. Fecundity had not returned after 4-5 estrous cycles. The other compounds produced no histologically evident long-lasting effects. Superficial endometrial damage seemed to be the mechanism of action of compounds that were effective on Day 3. The discrepancies noted between results obtained and the documented efficiency of PGF2alpha and of urea as abortifacients in humans raises the question of the suitability of the rat as a model for predicting abortifacient activity in humans. However, the action of these 2 substances may be different in later gestational phases.^ieng