Selective oestrogen receptor modulators/new antioestrogens: a clinical perspective

Following tamoxifen, the first selective oestrogen receptor modulator (SERM), a number of other antioestrogens have been developed. The first-generation SERMs exhibit cross-resistance with tamoxifen and have agonist effects on the uterus. Toremifene has equal efficacy to tamoxifen and may be useful as a tamoxifen alternative. Efficacy results for droloxifene and idoxifene were disappointing and their clinical development ceased. Response rates for second-generation SERMs such as raloxifene and arzoxifene are also not high, although raloxifene shows promise in the chemoprevention of breast cancer. Paradoxically, high-dose oestrogens are proving to be effective breast cancer treatment with similar responses to tamoxifen in postmenopausal women with advanced disease, although these drugs are not well tolerated. Fulvestrant is a new type of oestrogen receptor (ER) antagonist with no agonist effects, which binds, blocks and degrades the ER. Fulvestrant produces high response rates compared with the SERMs, is not cross-resistant with SERMs or aromatase inhibitors (AIs) and is equally as effective as the AI anastrozole in the treatment of postmenopausal women with advanced breast cancer who have progressed after prior antioestrogen therapy. Pure antioestrogens such as the ER antagonist fulvestrant provide opportunities for therapeutic sequencing with tamoxifen and AIs and offer exciting possibilities for the future treatment of breast cancer.

The estrogen suppression after sequential treatment with formestane in advanced breast cancer patients

In postmenopausal patients, estrogens have an important role in breast cancer growth and aromatase inhibitors (AI) suppress the aromatase enzyme system which converts androgens into estrogens. The aim of this study was to evaluate the effect on estrogen suppression of formestane 250 mg i.m. fortnightly, given immediately after the failure of a previous treatment with non-steroidal AI. Twenty-two advanced breast cancer patients progressing on letrozole, anastrozole and aminoglutethimide entered the study. At the beginning of the study, the serum estrogen levels were suppressed by the previous treatment with non-steroidal AI, and the following treatment with formestane moderately maintained this suppression; in four patients serum estrogen levels increased fivefold after 10 weeks. Neither complete nor partial responses were observed; 11 patients (50%) showed a stable disease lasting > or = 6 months, and the median time to progression was 6 months (range 3-9 months). No correlation was observed between clinical responses and serum estrogen suppression. Tolerability was satisfactory, and no patient withdrew from the study due to adverse events. In conclusion, formestane has demonstrated a moderate activity in estrogen suppression, and there is evidence that, at the failure of a previous treatment with non-steroidal AI, the sequential use of steroidal AI is feasible. This approach can be used in clinical practice in order to offer a disease control with a satisfactory quality of life.

G protein-coupled receptor 30 down-regulates cofactor expression and interferes with the transcriptional activity of glucocorticoid

G protein-coupled receptor 30 (GPR30) has previously been described to be important in steroid-mediated growth and to inhibit cell proliferation. Here we investigated whether the effect of GPR30 on cell growth is dependent on steroid hormone receptors. We stably introduced GPR30 in immortalized normal mammary epithelial (HME) cells using retroviruses for gene delivery. GPR30 inhibited the growth and proliferation of the cells. They expressed glucocorticoid receptor, but not estrogen or progesterone receptor. GPR30 down-regulated the expression of cofactor transcription intermediary factor 2 (TIF2) analyzed using quantitative RT-PCR analysis, and also diminished the expression of TIF2 at protein level analyzed by Western blotting using nuclear extracts from mammary epithelial cells. When HME cells were transiently transfected with the glucocorticoid response element MMTV-luc reporter plasmid, stable expression of GPR30 resulted in the abolition of ligand-induced transactivation of the promoter. In COS cells, transient transfection of GPR30 with glucocorticoid receptor alpha resulted in an abrogation of the MMTV-luc and GRE-luc reporter activities induced by dexamethasone. The results suggest a novel mechanism by which membrane-initiated signaling interferes with steroid signaling.

Autocrine stimulation of rhadinovirus-transformed T cells by the chemokine CCL1/I-309

The rhadinovirus herpesvirus saimiri transforms human T lymphocytes to stable growth in culture. Besides the viral oncogenes stpC and tip, little is understood about the transformation process at the cellular level. To identify cellular factors that might contribute to growth transformation, we compared cellular gene expression in pairs of herpesvirus saimiri-transformed and nontransformed human T-cell clones. Using cDNA arrays and suppressive subtractive hybridization, we were able to identify the chemokine CCL1/I-309 as one of the few cellular genes that are strongly overexpressed in T cells after growth transformation with herpesvirus saimiri. The transformed T cells expressed CCR8, the receptor for CCL1, which rapidly induced intracellular calcium ion levels. Neutralizing antibodies to CCL1 led to reduced secretion of interferon-gamma and tumor necrosis factor-alpha as well as to reduced proliferation rates in transformed T cells. Thus, we propose that growth transformation of human T cells with herpesvirus saimiri gives rise to an autocrine loop where the proliferation of transformed T cells is supported by the endogenous production of the chemokine CCL1.

In vivo fate-tracing studies using the Scl stem cell enhancer: embryonic hematopoietic stem cells significantly contribute to adult hematopoiesis

Evidence for the lineage relationship between embryonic and adult hematopoietic stem cells (HSCs) in the mouse is primarily indirect. In order to study this relationship in a direct manner, we expressed the tamoxifen-inducible Cre-ER(T) recombinase under the control of the stem cell leukemia (Scl) stem-cell enhancer in transgenic mice (HSC-SCL-Cre-ER(T)). To determine functionality, HSC-SCL-Cre-ER(T) transgenics were bred with Cre reporter mice. Flow cytometric and transplantation studies revealed tamoxifen-dependent recombination occurring in more than 90% of adult long-term HSCs, whereas the targeted proportion within mature progenitor populations was significantly lower. Moreover, the transgene was able to irreversibly tag embryonic HSCs on days 10 and 11 of gestation. These cells contributed to bone marrow hematopoiesis 5 months later. In order to investigate whether the de novo HSC generation is completed during embryogenesis, HSC-SCL-Cre-ER(T)-marked fetal liver cells were transplanted into adult recipients. Strikingly, the proportion of marked cells within the transplanted and the in vivo-remaining HSC compartment was not different, implying that no further HSC generation occurred during late fetal and neonatal stages of development. These data demonstrate for the first time the direct lineage relationship between midgestation embryonic and adult HSCs in the mouse. Additionally, the HSC-SCL-Cre-ER(T) mice will provide a valuable tool to achieve temporally controlled genetic manipulation of HSCs.

Breast cancer patients with progesterone receptor PR-A-rich tumors have poorer disease-free survival rates

PURPOSE

No study has yet analyzed whether changes in relative expression levels of progesterone receptor (PR) isoforms A and B in human breast tumors have significance in predicting clinical outcome. Human PRs are ligand-activated nuclear transcription factors that mediate progesterone action. Their presence in breast tumors is used to predict functional estrogen receptors (ERs) and, therefore, also to predict the likelihood of response to endocrine therapies and disease prognosis. The two PR isoforms, PR-A and PR-B, possess different in vitro and in vivo activities, suggesting that in tumors, the ratio of their expression may control hormone responsiveness. In general, PR-B are strong transcriptional activators, whereas PR-A can act as dominant repressors of PR-B and ER. Thus their balance may affect tamoxifen response in breast cancers.

EXPERIMENTAL DESIGN

To determine whether differential expression of the PR isoforms is associated with clinical outcome and hormonal responsiveness, PR-A and PR-B were measured by immunoblot analysis of cell lysates from 297 axillary node-positive breast tumors.

RESULTS

Expression of the two isoforms correlated with each other, as well as with ER. Additional analyses revealed that patients with PR-positive tumors but high PR-A:PR-B ratios, which were often caused by high PR-A levels, were 2.76 times more likely to relapse than patients with lower ratios, indicating resistance to tamoxifen.

CONCLUSIONS

This study suggests that knowledge of the PR-A:PR-B ratio may identify a subgroup of ER-positive/PR-positive patients with node-positive breast cancer that benefit poorly from endocrine therapy.

Anti-CD3 x anti-HER2 bispecific antibody effectively redirects armed T cells to inhibit tumor development and growth in hormone-refractory prostate cancer-bearing severe combined immunodeficient beige mice

The bispecific antibody (BiAb) anti-CD3 x anti-Her2/neu (Her2Bi), combines Her2/neu targeting with nonmajor histocompatibility complex-restricted cytotoxicity mediated by activated T cells (ATCs). To evaluate this adaptive immunotherapeutic strategy for augmenting antitumor immune response toward hormone-refractory prostate cancer (HRPC), normal donor or patient T cells were activated with anti-CD3, expanded ex vivo in interleukin-2, and then armed with Her2Bi (5-500 ng per million ATCs). In vitro, arming ATCs with Her2Bi increased the percent specific cytotoxicity toward PC-3 prostate adenocarcinoma cells 2-3 fold and increased the secretion of Th1 cytokines granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-alpha, and interferon-gamma when compared with unarmed ATCs or ATCs armed with an irrelevant BiAb. Her2Bi-armed ATCs administered with PC-3 (Winn Assay) or injected intratumorally prevented development or induced remissions, respectively, of PC-3 tumors in severe combined immunodeficient beige mice. Intravenously administered Her2Bi-armed ATCs localized to PC-3 xenografts mediated cytotoxicity toward tumor cells and produced significant tumor growth delay of PC-3 tumors, but not Her2/neu-negative LS174T colon adenocarcinoma xenografts. By flow cytometry analyses, Her2Bi-armed ATCs had a proliferative advantage over unarmed ATCs and persisted in the circulation and tumor tissues longer than unarmed ATCs. These findings suggest that Her2Bi-armed ATC therapy may be an effective, nontoxic, tumor-specific treatment for Her2-positive HRPC.

Inverse relationship between ER-beta and SRC-1 predicts outcome in endocrine-resistant breast cancer

The oestrogen receptor (ER) interacts with coactivator proteins to modulate genes central to breast tumour progression. Oestrogen receptor is encoded for by two genes, ER-α and ER-β. Although ER-α has been well characterized, the role of ER-β as a prognostic indicator remains unresolved. To determine isoform-specific expression of ER and coexpression with activator proteins, we examined the expression and localisation of ER-α, ER-β and the coactivator protein steroid receptor coactivator 1 (SRC-1) by immunohistochemistry and immunofluorescence in a cohort of human breast cancer patients (n=150). Relative levels of SRC-1 in primary breast cultures derived from patient tumours in the presence of β-oestradiol and tamoxifen was assessed using Western blotting (n=14). Oestrogen receptor-β protein expression was associated with disease-free survival (DFS) and inversely associated with the expression of HER2 (P=0.0008 and P<0.0001, respectively), whereas SRC-1 was negatively associated with DFS and positively correlated with HER2 (P<0.0001 and P<0.0001, respectively). Steroid receptor coactivator 1 protein expression was regulated in response to β-oestradiol or tamoxifen in 57% of the primary tumour cell cultures. Protein expression of ER-β and SRC-1 was inversely associated (P=0.0001). The association of ER-β protein expression with increased DFS and its inverse relationship with SRC-1 suggests a role for these proteins in predicting outcome in breast cancer.

Correlations in the cytokine system in endometrial hyperplasia

Correlations between local expression of insulin-like growth factor 1, insulin-like growth factor receptor, epithelial growth factor, transforming growth beta2 factor, PCNA, TNF-alpha, TNF receptor 1, Fas, FasL, IFN-gamma, IL-1beta, IL-4, IL-6, IL-8, IL-10, and IL-12 genes in intact and hyperplastic endometrium and in the endometrium after hormone therapy were analyzed. Numerous correlations at the proliferation and secretion stages of the menstrual cycle indicate balanced cytokine system. The number of correlations decreases in glandular cystic and more so in atypical hyperplasia, indicating imbalance in the cytokine system. Dufastone and zoladex therapy did not lead to recovery of this balance, but higher correlations between the expression of some factors of cell proliferation attest to the beginning of normalization of pathologically changed endometrium.

Arginine deiminase enhances dexamethasone-induced cytotoxicity in human T-lymphoblastic leukemia CCRF-CEM cells

Since arginine deiminase (ADI; EC 3.5.3.6) inhibits cell proliferation by arresting cells in the G1 phase, we tested its synergistic effect on cell death induced by dexamethasone (DEX), which also induces apoptosis by G1 cell cycle arrest. ADI inhibited cell proliferation and induced apoptosis in human leukemic CEM cells in a dose-dependent manner. Simultaneous treatment with ADI and DEX showed synergistic effects on DNA fragmentation and LDH release. In addition, ADI exerted its anti-proliferative activity against DEX-resistant CEM cells. ADI suppressed expression of c-myc, a potential key regulator of cell proliferation and apoptosis, and increased expression of p27Kip1 cyclin-dependent kinase inhibitor. These results suggest that ADI efficiently increases the anti-cancer effect of DEX on human leukemic CEM cells through G1 cell cycle arrest involving downregulation of c-myc and upregulation of p27Kip1.

[Inhibitory effects of celecoxib combined with octreotide on growth of multidrug resistant human gastric cancer cell line SGC7901/ADR]

BACKGROUND & OBJECTIVE

Both cyclooxygenase-2 (COX-2) inhibitor and octreotide can inhibit growth of tumor cells. This study was to investigate inhibitory effects of COX-2 inhibitor celecoxib alone, and celecoxib combined with octreotide on growth of multidrug resistant human gastric cancer cell line SGC7901/ADR.

METHODS

Experimental groups:(1)celecoxib (1 x 10(-4)-1 x 10(-8) mol/L); (2)octreotide (1 x 10(-5)-1 x 10(-9) mol/L); (3)celecoxib (1 x 10(-4)-1 x 10(-8) mol/L) combined with octreotide (1 x 10-6 mol/L);(4)control group (RPMI-1640 medium without serum). The effects of all treatments on SGC7901 cells, and SGC7901/ADR cells were observed. Cell proliferation was measured by (3)H-thymidine incorporation into DNA. The expression of proliferating cell nuclear antigen (PCNA) was detected by immunocytochemistry. Cell apoptosis was measured by TdT-mediated dUTP nick end-labeling assay (TUNEL) and flow cytometry.

RESULTS

(3)H-thymidine incorporation into SGC7901/ADR cells treated with celecoxib [(471.3+/-79.7) cpm] was significantly lower than that of control group [(917.5+/-130.8) cpm](P< 0.05). When combined with octreotide, celecoxib presented lower (3)H-thymidine incorporation [(220.0+/-19.7)cpm] than it alone with a 53.3% decrease. The concentration of celecoxib in combination group negatively related to synthesis of DNA in SGC7901/ADR cells (r=0.996,P< 0.001). The expression of PCNA in either celecoxib group or combination group markedly decreased. The apoptosis rates of SGC7901/ADR cells induced by celecoxib alone, and combination treatment were 32.9%, and 52.5%.

CONCLUSION

Celecoxib combined with octreotide may enhance inhibition of growth of multidrug resistant human gastric cancer cells. The mechanism may be related with inhibiting DNA synthesis, and inducing apoptosis.

Deregulation of estrogen receptor coactivator proline-, glutamic acid-, and leucine-rich protein-1/modulator of nongenomic activity of estrogen receptor in human endometrial tumors

Proline-, glutamic acid-, and leucine-rich protein-1)PELP1/MNAR [modulator of nongenomic activity of estrogen receptor (ER)], a novel coregulatory protein, modulates genomic as well as nongenomic activity of ERs. We characterized the expression and localization of PELP1 in both benign and cancerous endometrium. Our results suggest that PELP1 is expressed in all stages of endometrium; however, this protein exhibits distinct localization depending on the phase. PELP1 is expressed in both the stroma and epithelial cells. Using the Ishikawa endometrial cancer model cell line and ER subtype-specific ligands, we found that PELP1 functionally interacts with both ERalpha and ERbeta and enhances their transcriptional responses. However, in endometrial cancer cells, endogenous PELP1 is also required for optimal ligand-mediated transcription and proliferation responses. PELP1 promoted a tamoxifen-mediated agonistic action in endometrial, but not in breast cancer cells. PELP1 expression and localization are widely deregulated in endometrial cancers. In addition, PELP1 and ERbeta were localized predominantly in the cytoplasm of high-grade endometrial tumors. Our results suggest that PELP1 plays an essential role in the proliferation of cancerous endometrial cells.

Global Inhibition of Lef1/Tcf-dependent Wnt Signaling at Its Nuclear End Point Abrogates Development in Transgenic Xenopus Embryos

Analysis of canonical Wnt signaling during vertebrate development by means of knock-out or transgenic approaches is often hampered by functional redundancy as well as pathway bifurcations downstream of the manipulated components. We report the design of an optimized chimera capable of blocking transcriptional activation of Lef1/Tcf-beta-catenin target genes, thus enabling intervention with the canonical Wnt pathway at its nuclear end point. This construct was made hormone-inducible, both functionally and transcriptionally, and was transgenically integrated in Xenopus embryos. Down-regulation of target genes was clearly observed upon treatment of these embryos with dexamethasone. In addition, exposure of variously aged transgenic embryos to dexamethasone caused complex phenotypes with many new but also several recognizable features stemming from inhibition of canonical Wnt signaling. At least in some tissues, a significant reduction in cell proliferation and an increase in programmed cell death appeared to underlie these phenotypes. Our inducible transgenic system can serve a broad range of experimental settings designed to unveil new functional aspects of Lef1/Tcf-beta-catenin signaling during vertebrate embryogenesis.

Tamoxifen exerts agonistic effects on clusterin and complement C3 gene expression in RUCA-I primary xenografts and metastases but not normal uterus

Tamoxifen is the most widely prescribed anti-neoplastic drug for the treatment of both localized and metastatic breast cancer. It is also the prototype for a class of drugs that are referred to as selective estrogen receptor modifiers (SERMs), most of which have both estrogenic and anti-estrogenic activity in estrogen target tissues including the breast and endometrium. The underlying mechanisms of action of SERMs in the breast and endometrium that lead to profound differences in the tissue-specific effects of tamoxifen have not yet been elucidated. We have compared the effects of tamoxifen and the pure anti-estrogen ICI 182,780 (Faslodex) in the RUCA-I hormone-responsive rat endometrial cell line in vitro and in vivo. In cell culture, RUCA-I cells responded to both estrogens and anti-estrogens, and the expression of clusterin and complement C3 mRNAs required the presence of estradiol and was repressed in the absence of estradiol or in the presence of the pure anti-estrogen ICI 182,780. Tamoxifen, on the other hand, induced both complement C3 and clusterin mRNA in the absence of estradiol and failed to repress their expression in the presence of estradiol. When grown as subcutaneous xenografts in syngeneic Da/Han rats for 5 weeks, the RUCA-I cells retained their sensitivity to estradiol, as demonstrated by significantly enhanced tumor growth in intact female rats compared with the growth in ovariectomized rats. But neither ICI 182,780 nor tamoxifen had a significant impact on tumor growth in cycling or ovariectomized animals. On the other hand, tamoxifen was potently estrogenic in metastatic lymph nodes, increasing the size of the lymph node tumors almost 6-fold over that seen in the intact cycling animals. In primary tumors, the expression of complement C3 mirrored that seen in vitro, although tamoxifen showed some agonist activity in ovariectomized animals. Tamoxifen also displayed marked agonist activity with respect to clusterin expression and enhanced clusterin mRNA levels and protein in both the primary tumors and lymph metastases in intact and ovariectomized animals. Given the recent demonstration that over-expression of clusterin increases the metastatic potential of breast cancer cells, these data may provide a mechanistic explanation for the increased incidence of endometrial cancer in postmenopausal patients treated with tamoxifen.

Management of patients with hormone refractory prostate cancer

Prostate cancer is the second most common cancer in men in the UK, and the incidence of prostate cancer has increased dramatically over the past two decades. Although most men are diagnosed at early stage, more than 50% develop locally advanced or metastatic disease. Androgen ablation with luteinising hormone-releasing hormone (LHRH) agonists alone, or in combination with anti-androgens, is the standard treatment for men with metastatic prostate cancer. Unfortunately, almost all men develop progressive disease after a variable time period, despite the maximal androgen blockade. The management of hormone refractory prostate cancer (HRPC) is challenging, as there is no uniformly accepted strategy. Various treatment options, including second-line hormone therapy, are discussed. Chemotherapy is being increasingly used and, importantly, docetaxel and estramustine may play an important role in the near future. The role of radiotherapy, strontium-89, bisphosphonates, novel agents and future therapies are also outlined.

Tamoxifen and pregnancy

Women are conventionally advised to stop tamoxifen before attempting pregnancy. The risks of congenital malformations or late teratogenic manifestations in adulthood are unknown. Following an informed discussion about the uncertainties of tamoxifen exposure on pregnancy women should be offered the choice whether to continue or stop tamoxifen before attempting pregnancy. An unexpected pregnancy in a women taking tamoxifen could continue if the pregnant woman accepts the possibility of a teratogenic effect that tamoxifen could have on the fetus.

Phthalates inhibit tamoxifen-induced apoptosis in MCF-7 human breast cancer cells

Environmental estrogens represent a class of compounds that can mimic the function or activity of the endogenous estrogen 17 -estradiol (E2). Phthalates including butyl benzyl phthalate (BBP), di(n-butyl) phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP) are used as plasticizers, and also widely used in food wraps and cosmetic formulations. Phthalates have been shown to mimic estrogen and are capable of binding to the estrogen receptor (ER). It has been demonstrated that estrogen promotes drug resistance to tamoxifen (TAM) in breast cancer. In order to further evaluate the potential role of the phthalates as environmental estrogens, the effect of phthalates was investigated on TAM-induced apoptosis in MCF-7 human breast cancer cells. Our results show that phthalates, BBP (100 M), DBP (10 M), and DEHP (10 M), significantly increased cell proliferation in MCF-7, but not in MDA-MB-231 cells. In addition, BBP, DBP, and DEHP mimicked estrogen in the inhibition of TAM-induced apoptosis in MCF-7 cells. Our data suggest that the inhibitory effect of phthalates on TAM-induced apoptosis involves an increase in intracellular Bcl-2 to Bax ratio. Given that the phthalates are widely used in cosmetics mainly for women, our findings that revealed the promoting effect of BBP, DBP, and DEHP on chemotherapeutic drug resistance to TAM in breast cancer may be of biological relevance.

Arimidex inhibition on proliferation of human breast solid tumors measured by ATP bioluminescence

To determine the degree of Arimidex (Anastrozole) inhibition on proliferation of human breast solid tumors in vitro by ATP bioluminescence assay. Breast cancer solid tumors with different hormone receptors and grading were collected from 38 Chinese women with invasive breast cancers. Tumors were treated with three concentrations of Arimidex (1.5 mM, 15 mM and 150 mM). ATP bioluminescence assay was used to measure the metabolic rate in order to determine the degree of inhibition of Arimidex on the breast cancer tumors by comparing to the untreated tumors. 15 mM Arimidex shows greatest inhibitory effect on the proliferation of solid tumors with ER-postive/PR-positive. It can also inhibit the growth of metastatic tumors and tumors with HER-2/neu expression. It shows greater inhibitory effect in lower grading of tumors then higher. Arimidex may effectively inhibit the growth of breast tumors in in vitro system by inhibiting aromatase and block estrogen dependent tumor growth.

Tamoxifen resistance in breast cancer cells is accompanied by an enhanced motile and invasive phenotype: inhibition by gefitinib ('Iressa', ZD1839)

Despite an initial response to antihormonal therapies, the development of resistance will occur in a significant number of breast cancer patients. The mechanisms that underlie acquired resistance are not yet clear. Using a previously established in vitro cell model of tamoxifen resistance in MCF7 cells, shown to display autocrine epidermal growth factor receptor (EGFR) signalling, we assessed how resistance might modulate their metastatic phenotype in vitro, as metastatic disease is the single most important factor affecting the mortality of cancer patients. Furthermore, we investigated the effect of the EGFR tyrosine kinase inhibitor (EGFR-TKI), gefitinib ('Iressa', ZD1839; AstraZeneca), on this behaviour. The acquisition of tamoxifen resistance in MCF7 cells was accompanied by a dramatic and significant increase in their invasive and motile nature. The affinity of these cells for matrix components was also enhanced. Inhibition of EGFR signalling with gefitinib reduced both basal and TGF-alpha-stimulated invasion and motility and reduced cell-matrix adhesion. In conclusion, we demonstrate here that resistance to tamoxifen in breast cancer cells is accompanied by a significant increase in their basal motile and invasive activity, properties associated with increased metastatic potential. Inhibition of EGFR signalling by gefitinib significantly inhibited cell motility and invasion thus suggesting a role for the EGF receptor in the aggressive phenotype of tamoxifen-resistant breast cancer cells.

Pure antiestrogen RU 58668-loaded nanospheres: morphology, cell activity and toxicity studies

Nanospheres (NS) formulated using biodegradable and biocompatible polymers, poly(D,L-lactide-co-glycolide) (PLGA), poly(D,L-lactide) (PLA) and poly(epsilon-caprolactone) (PCL), loaded with the pure anti-estrogen RU 58668 (RU), a promising estrogen-dependent anticancer agent, have been prepared. They all possess a small size compatible with an intratumoral extravasation behavior and their pegylation reduce significantly their zeta potential. Characterization by freeze fracture electron microscopy have shown that NS are spheric particles with a size ranging between 30 and 50nm and a tendency to agglomerate which is reduced by polyethylene glycol (PEG) grafting. PEG-grafted NS are all non-toxic as revealed by cell viability assay. A specific cellular model has been used to evaluate not only the release extent of the drug but also its biological activity. All formulations tested showed that they release slowly RU as measured by the delayed ability of RU to inhibit estrogen-induced transcription in human breast cancer cells and that they possess only a small amount of surface adsorbed RU.

Homologous up-regulation of androgen receptor expression by androgen in vascular smooth muscle cells

OBJECTIVE

Androgens play an important role in the arterial vascular system, and androgen receptors (AR) have been identified in vascular smooth muscle cells (VSMCs). This study examined the effects of testosterone exposure on AR gene expression in cultured rat aortic smooth muscle cells.

METHODS

Changes in AR protein and messenger RNA (mRNA) levels after androgen exposure were determined using immunoblotting and Northern blotting analysis respectively.

RESULTS

Treatment of synchronized VSMCs with testosterone increased both cytoplasmic and nuclear AR protein expression in a dose- and time-dependent fashion, whereas exposure of VSMCs to androgen for 10 min induced a transient down-regulation of AR protein. Meanwhile, AR mRNA level was also up-regulated, but to a much smaller extent. Pretreatment with transcription inhibitor and translation inhibitor repressed cytoplasmic AR protein levels to 46 and 12% (means) of the androgen treatment control level respectively. Furthermore, androgen up-regulation of intracellular AR protein was partially inhibited by androgen antagonist.

CONCLUSIONS

Androgen increases AR expression in VSMCs at the level of both transcription and non-transcription.

Hypersensitive K303R oestrogen receptor-alpha variant not found in invasive carcinomas

Introduction

Genetic abnormalities or mutations in premalignant breast lesions may have a role in progression toward malignancy or influence the behaviour of subsequent disease. The A908G (Lys303→Arg) change in the gene encoding oestrogen receptor-α (ER-α) creates a hypersensitivity to oestradiol and would have significant consequences if present in breast carcinoma, especially those treated with endocrine therapy. We have therefore examined a panel of endocrine-treated invasive carcinomas for the presence of this mutation.

Methods

Sequencing of control DNA was shown to detect mutation present in as little as 15% of the starting material. Enrichment for the mutation by using MboII restriction digestion allowed the detection of mutant present at 1% or less. We applied these techniques to genomic DNA and cDNA from 136 invasive breast carcinomas.

Results

No evidence of the A908G mutation was found with either technique. The incidence of this mutation in our panel of tumours is therefore significantly less than previously reported.

Conclusion

The fact that the mutation was not found leads us to believe that this mutation is absent from most cells in invasive carcinomas and furthermore that the major expression product of the ER-α gene in cancers does not contain the K303R mutation. It is therefore unlikely to influence the effectiveness of endocrine treatment.

Pharmacodynamic Equivalence of a Decapeptyl 3-Month SR Formulation with the 28-Day SR Formulation in Patients with Advanced Prostate Cancer

AIMS

The objective of the study was to assess the pharmacodynamic equivalence of LHRH analogue triptorelin 3-month and 28-day SR formulations.

METHODS

Patients with documented locally advanced or metastatic prostate cancer were randomized to receive one injection of the 3-month formulation (n = 63) or three injections at 28-day intervals of the 28-day formulation (n = 68). Group-chemical castration rates defined as the percentage of patients reaching a testosterone plasma level </=0.5 ng/ml were compared at D84 (i.e., 3 x 28 days). Testosterone, LH and triptorelin plasma profiles, and change from baseline in plasma PSA were assessed over 3 months (from baseline to D91).

RESULTS

Chemical castration rates were 98 and 96% in the 3-month and 28-day formulation groups, respectively, with confidence interval (two-sided 94.2% CI) of [-8.1%; 9.6%]. Median times to reach chemical castration were 18.8 and 18.5 days (p = 0.86, log rank), respectively. Ratios for mean peak plasma levels and AUC(91) of the two formulations for both testosterone and LH fell within the [0.80; 1.25] equivalence interval. Mean PSA decreases from baseline at D91 were 91.0 and 91.7%, respectively (p = 0.73).

CONCLUSION

Treatments with the two triptorelin formulations over 3 months are pharmacologically equivalent.