bluuebunny/crossref_metadata_2025 huggingface dataset:
Estrogen production in endometriosis and use of aromatase inhibitors to treat endometriosis.
Authors: Bulun S E , Zeitoun K , Takayama K , Noble L , Michael D , Simpson E , Johns A , Putman M , Sasano H
Published: December 2004

Estrogen is the most important known factor that stimulates the growth of endometriosis. Estrogen delivery to endometriotic implants was classically viewed to be only via the circulating blood in an endocrine fashion. We recently uncovered an autocrine positive feedback mechanism, which favored the continuous production of estrogen and prostaglandin (PG)E2 in the endometriotic stromal cells. The enzyme, aromatase, is aberrantly expressed in endometriotic stromal cells and catalyzes the conversion of C19 steroids to estrogens, which then stimulate cyclooxygenase-2 to increase the levels of PGE2. PGE2, in turn, is a potent inducer of aromatase activity in endometriotic stromal cells. Aromatase is not expressed in the eutopic endometrium. Aromatase expression in endometriosis and its inhibition in eutopic endometrium are controlled by the competitive binding of a stimulatory transcription factor, steroidogenic factor-1, and an inhibitory factor, chicken ovalbumin upstream promoter-transcription factor to a regulatory element in the aromatase P450 gene promoter. In addition, we find that endometriotic tissue is deficient in 17beta-hydroxysteroid dehydrogenase type 2, which is normally expressed in eutopic endometrial glandular cells and inactivates estradiol-17beta to estrone. This deficiency is another aberration that favors higher levels of estradiol-17beta in endometriotic tissues in comparison with the eutopic endometrium. The clinical relevance of local aromatase expression in endometriosis was exemplified by the successful treatment of an unusually aggressive form of recurrent endometriosis in a postmenopausal woman using an aromatase inhibitor.
Aromatase and gynecomastia.
Authors: Braunstein G D
Published: December 2004

An imbalance between estrogen action relative to androgen action at the breast tissue level results in gynecomastia. Enhancement of aromatization of androgens to estrogens is important in the pathogenesis of gynecomastia associated with obesity, aging, puberty, liver disease, thyrotoxicosis, 17-oxosteroid reductase deficiency. Klinefelter's syndrome, and neoplasms of the testes, adrenals and liver. A primary aromatase excess syndrome with exuberant gynecomastia had been found both sporadically and in a familial setting. Although aromatase inhibition would appear to be an important class of drugs to treat gynecomastia, relatively little published data with these drugs exist and most concern the use of delta1-testolactone, which reduces the size of the breast glandular tissue, but does not completely ameliorate the problem. Studies with the newer generation of more potent aromatase inhibitors need to be carried out.
Risks versus benefits in the clinical application of aromatase inhibitors.
Authors: Goss P E
Published: December 2004

Third-generation aromatase inhibitors are able to reduce circulating plasma estrogen concentrations in postmenopausal women to below detectable limits and significantly inhibit aromatase, the enzyme responsible for estrogen synthesis, in normal breast tissue and breast tumors. Their role in the treatment of advanced breast cancer is well established and their use in adjuvant therapy is currently being explored. On the basis of these trials, evaluation of these inhibitors in the prevention of breast cancer may be appropriate. Aromatase inhibitors have non-specific toxic side effects including (but not limited to): asthenia, headache, nausea, peripheral edema, fatigue, vomiting and dyspepsia. In addition, certain endocrinological side effects in postmenopausal women are notable, namely hot flushes and vaginal dryness. In advanced breast cancer, these side effects result in treatment withdrawal in few (<4%) women. Of concern, however, are the potential long-term endocrinological side effects in women receiving treatment as first-line adjuvant therapy or in sequence or combination with tamoxifen or other selective estrogen receptor modulators (SERMs). Current studies of adjuvant treatments for breast cancer in healthy women are carefully evaluating, in addition to general toxicities, the effects on bone, lipid metabolism, cardiovascular risk, quality of life and menopausal symptoms. Careful evaluation of all-cause morbidity and mortality is necessary to plan trials and justify long-term use of aromatase inhibitors in the treatment or prevention of breast cancer in healthy women.
Methylation mechanisms in pituitary tumorigenesis.
Authors: Farrell W E , Simpson D J , Frost S J , Clayton R N
Published: December 2004

Methylation is essential for embryonic development, however aberrant methylation of CpG islands associated with the tumour suppressor genes (TSGs) and leading to gene silencing is found in numerous tumour types. The TSG p16/CDKN2A is involved in the genesis of many tumour types and frequent methylation of the CpG island of the p16/CDKN2A gene is associated with loss of protein expression in pituitary tumours. In addition, CpG sites are mutational hotspots and abnormal methylation patterns have been shown to lead to genetic instability, predisposing to, and preceding allelic loss. Although several studies of pituitary tumours have shown loss of genetic material at known and putative TSGs loci, studies of the retained alleles have revealed infrequent mutation. Equally, for several other TSGs no mechanisms have been described for their reduced expression. Methylation may represent a unifying theme, responsible in some cases for an absence or reduced expression and in other cases predisposing to allelic loss that may or may not encompass a TSG. In several tumour types treatment of tumours or their cognate cell lines with demethylating agents induces expression of previously methylated genes. Using the mouse corticotroph cell line AtT20 as a model system, transfection studies showed restoration of growth control through induction of ectopically expressed p16/CDKN2A. These effects were reversed by prior in vitro methylation of the constructs' CpG sites within the coding region of this gene. Methylation of an otherwise unmethylated CpG island renders a gene transcriptionally incompetent and clinically these genes represent attractive therapeutic targets since the gene is neither lost nor mutated, but may be reactivated. Future studies will no doubt describe more efficacious pharmacological interventions and identify the mechanisms responsible for the abnormal methylation patterns seen in tumours including those of pituitary origin.
Prostate cancer: molecular biology of early progression to androgen independence.
Authors: Sadar M D , Hussain M , Bruchovsky N
Published: December 2004

To improve the therapy for prostate cancer, it will be necessary to address the problems of progression to androgen independence and the process of metastatic spread of tumour. The complexity of the latter condition is likely to mitigate against the immediate development of relevant therapeutic approaches. However, the basis of androgen independence appears to be a problem of simpler dimensions and more amenable to treatment with current therapeutic technology. Since early tumour progression can be detected by an incomplete prostate-specific antigen (PSA) response to androgen withdrawal therapy, a study of the molecular biology of PSA gene regulation may well provide insight into new methods for preventing or delaying this problem. Mounting evidence suggests that ligand-independent activation of the androgen receptor may be one underlying mechanism of androgen independence. In the absence of androgen, a compensatory increase in the activity of cAMP-dependent protein kinase (PKA) enhances the ability of the androgen receptor to bind to the response elements regulating PSA gene expression. The activation of the androgen receptor through up-regulation of the PKA signal transduction pathway involves the amino-terminus of the androgen receptor, the function of which may be altered either by modifications such as phosphorylation, or through interactions with co-regulators or other proteins. Of therapeutic interest is the fact that this effect can be counteracted experimentally by the anti-androgen, bicalutamide, and clinically by several other similar agents. We speculate that the inhibition of PKA-activated androgen receptor might also be accomplished by decoy molecules that can bind to the relevant activated site on the amino-terminus or competitively interact with proteins recruited by the PKA pathway that are responsible for activating the receptor in the absence of androgen. Such molecules might include small mimetic substances or agents that can gain access to the nucleus of the cell.
PTEN, a unique tumor suppressor gene.
Authors: Dahia P L
Published: December 2004

For many years, it has been thought that the chromosome region 10q22-24 includes one or more genes that appear to play a role in several human malignancies. PTEN is a new tumor suppressor gene encoding a dual-specificity phosphatase that was cloned simultaneously by three groups (Li & Sun 1997, Li et al. 1997, Steck et al. 1997), two of which used a positional cloning approach to identify genes in chromosome 10 (Li et al. 1997, Steck et al. 1997). While several protein kinases have been implicated as oncogenes, and phosphatases have long been known frequently to antagonize their function, there has been no direct demonstration of the role of phosphatases in tumor development (Myers & Tonks 1997). PTEN characterization as a bona fide tumor suppressor gene has confirmed that a deficient phosphatase activity can lead to cancer, as detailed by studies that are described below.
Preoperative endocrine therapy for breast cancer.
Authors: Cheung K L , Howell A , Robertson J F
Published: December 2004

The preoperative use of systemic therapy for primary breast cancer has the potential to downstage tumours. This would render suitable for breast conservation some tumours that were unsuitable at initial presentation, or would convert some inoperable locally advanced breast cancers into tumours that are operable. No survival benefit has been demonstrated for neoadjuvant chemotherapy compared with the same therapy given in an adjuvant setting. Preoperative endocrine therapy, in contrast to neoadjuvant chemotherapy, has fewer side effects and has the potential additional advantage that it can be continued throughout the perioperative period. Current data have shown that, in patients with an oestrogen receptor (ER)-positive tumour, a response approaching 70% could be reached in approximately 3 months using traditional endocrine manipulation such as tamoxifen. Randomised clinical trials are warranted to demonstrate the superiority of preoperative endocrine therapy over conventional adjuvant endocrine therapy, to define the optimum duration of therapy, and to identify the best endocrine agents. Both clinical and laboratory studies are also required to identify factors (in addition to ER) that would precisely predict the response and hence to select appropriate patients and to improve existing methods of monitoring response.
c-Myc in breast cancer.
Authors: Liao D J , Dickson R B
Published: December 2004

Ever since Bishop and his co-workers discovered the c-myc gene in the late 1970s (Bishop 1982), voluminous literature has documented its central role in proliferation and malignant transformation of human and animal cells (Amati et al. 1998, Bouchard et al. 1998, Dang et al. 1999). Most, if not all, types of human malignancy have been reported to have amplification and/or overexpression of this gene, although the frequency of these alterations varies greatly among different reports (Nesbit et al. 1999). In 1992, researchers started to realize that aberrant expression of c-myc could cause apoptosis (Evan et al. 1992, Shi et al. 1992), although the phenomenon had actually been observed much earlier (Wurm et al. 1986). Studies in recent years have further shown that the c-myc gene regulates growth, both in the sense of cell size and in the context of tissue differentiation (Gandarillas & Watt 1997, Iritani & Eisenman 1999, Johnston et al. 1999, Schmidt 1999, Schuhmacher et al. 1999). Thus, it is now known that the c-myc gene participates in most aspects of cellular function, including replication, growth, metabolism, differentiation, and apoptosis (Packham & Cleveland 1995, Hoffman & Liebermann 1998, Dang 1999, Dang et al. 1999, Elend & Eilers 1999, Prendergast 1999). How the c-Myc protein may be specifically directed to perform one, but not the others, of these functions is still obscure, despite the fact that the relevant literature has been accumulating at a fast pace in the past two decades. This review focuses on the profound roles of c-Myc in breast cancer and in the actions of the hormones that are eitologically related to breast cancer.
Phytoestrogens after breast cancer.
Authors: This P , De La Rochefordi√®re A , Clough K , Fourquet A , Magdelenat H , _ _
Published: December 2004

The current extension of the indications for adjuvant chemotherapy, which predisposes to early menopause, and the media coverage of the benefits of hormone replacement therapy (HRT) have led patients with a history of breast cancer to seek treatments for estrogen deprivation. In breast cancer survivors, most physicians avoid HRT because of concern regarding the potential promotion of growth of occult malignant cells by estrogens, due to the estrogen dependence of breast cancer. Soy phytoestrogens are being promoted as the 'natural alternative' to HRT and have been available without restrictions for several years as nutritional supplements. In this paper, data on the complex mammary effects of phytoestrogens in epidemiological studies, in in vitro studies, as well as in in vivo studies on animal carcinogenesis are reviewed. The potential benefits and risks of phytoestrogens are analyzed, and the prescription of phytoestrogens to postmenopausal women after breast cancer and the coprescription with the anti-estrogen tamoxifen are discussed. The absence of controlled trials and technical checking of extraction and titration in these preparations on 'free sale' raise a new problem in terms of public health and justify close reasoning and a cautious attitude of physicians, as well as straight information given to women, especially after breast cancer.
The ErbB receptor tyrosine family as signal integrators.
Authors: Hynes N E , Horsch K , Olayioye M A , Badache A
Published: December 2004

ErbB receptor tyrosine kinases (RTKs) and their ligands have important roles in normal development and in human cancer. Among the ErbB receptors only ErbB2 has no direct ligand; however, ErbB2 acts as a co-receptor for the other family members, promoting high affinity ligand binding and enhancement of ligand-induced biological responses. These characteristics demonstrate the central role of ErbB2 in the receptor family, which likely explains why it is involved in the development of many human malignancies, including breast cancer. ErbB RTKs also function as signal integrators, cross-regulating different classes of membrane receptors including receptors of the cytokine family. Cross-regulation of ErbB RTKs and cytokines receptors represents another mechanism for controlling and enhancing tumor cell proliferation.
Studies of epidermal growth factor receptor inhibition in breast cancer.
Authors: Bundred N J , Chan K , Anderson N G
Published: December 2004

Until recently, there has been little knowledge on the growth control of oestrogen receptor (ER)-negative ductal carcinoma in situ (DCIS) and invasive breast cancer. The recent development of DCIS models, such as transgenic mice, cell-line xenograft models and, importantly, in vivo human DCIS xenograft models has facilitated the investigation and understanding of the control of growth of early pre-invasive breast lesions. Recent studies have shown that ER-negative DCIS, unlike ER-positive DCIS, is hormone independent and does not respond to anti-oestrogen treatment. Moreover, DCIS of the comedo type utilises type I tyrosine kinase growth factors, such as epidermal growth factor receptor (EGFR) and c-erbB-2, in receptor signalling for growth. New data underscore the importance of EGFR as the major modulating growth factor receptor in the control of proliferation in the breast. Pre-clinical studies performed on human DCIS xenografts in nude mice suggest a potential role for EGFR tyrosine kinase inhibitors (EGFR-TKIs). More specifically, ZD1839, a novel orally active and selective EGFR-TKI, has been shown to produce a response in DCIS through a decrease in epithelial proliferation. These findings have enhanced our knowledge of signal transduction pathways in cancer and indicate that tyrosine kinase blockade of EGFR has potential for the treatment and chemoprevention of DCIS. It is hoped that further advances in this area and evaluation of EGFR-TKIs in Phase II/III clinical trials will allow their therapeutic potential as anticancer agents to be appreciated.
Fibroblast growth factor signalling in mouse mammary gland development.
Authors: Spencer-Dene B , Dillon C , Fantl V , Kerr K , Petiot A , Dickson C
Published: December 2004

Fibroblast growth factors (Fgfs) and their receptors are important intercellular signalling molecules involved in many aspects of animal development. The aberrant expression of the Fgfs or the inappropriate activation of their cell surface receptors have been implicated in tumorigenesis. Here, we describe the evidence that as well as playing a critical role in the formation of the mammary primordia during embryogenesis, signalling by Fgfs is necessary for optimal lobuloalveolar development of the mouse mammary gland during pregnancy.
Discovery of a novel Raf kinase inhibitor.
Authors: Lyons J F , Wilhelm S , Hibner B , Bollag G
Published: December 2004

We discuss the biology of Ras signal transduction and the epidemiology of ras mutations in association with disease as a background for the development of a Raf kinase inhibitor, BAY 43-9006. Knowledge of Ras effector pathways has permitted genetic validation of numerous targets involved in the Ras signaling cascade. A key Ras effector pathway involves the kinase cascade RAF/MEK/ERK (MEK: MAP/ERK kinase; ERK: extracellular signal related kinase). Indeed, we present studies of cell lines stably expressing mutant MEK constructs, which point to Raf kinase as a target for therapeutics with selective anti-tumor activity. Finally, a small molecule drug discovery program based on inhibition of Raf kinase activity is outlined and the initial pre-clinical development process of the Raf kinase inhibitor BAY 43-9006 is discussed.
Farnesyl transferase inhibitors--a novel therapy for breast cancer.
Authors: Johnston S R , Kelland L R
Published: December 2004

Inhibitors of the enzyme farnesyl protein transferase prevent a key step in the post-translational processing of the Ras protein, and were developed initially as a therapeutic strategy to inhibit cell signalling in ras-transformed cells. As more has been learnt about the biological effects of farnesyl transferase inhibitors (FTIs) on cancer cells, it is clear that tumours without oncogenic ras mutations such as breast cancer may also be targets for FTI therapy. This article reviews the rationale for the development of FTIs, focussing on early preclinical data in breast cancer models together with preliminary results from the first phase II study of an FTI in advanced breast cancer.
Progress in breast cancer chemoprevention.
Authors: Arun B , Hortobagyi G N
Published: December 2004

Over the past years there have been significant advances in breast cancer treatment and early detection. For the first time, a decrease in cancer mortality has been observed. Recently, much progress has been made in the understanding of carcinogenesis partly due to available new technologies to detect early molecular changes in the tissue. The knowledge of breast cancer carcinogenesis has provided possible opportunities to prevent breast cancer. Currently, several clinical breast cancer prevention trials are ongoing. This paper reviews issues related to breast cancer chemoprevention including identification of high risk cohorts, endpoint biomarkers, current and new chemopreventive agents as well as models to evaluate these agents.
A critical reappraisal of MIB-1 labelling index significance in a large series of pituitary tumours: secreting versus non-secreting adenomas.
Authors: Jaffrain-Rea M L , Di Stefano D , Minniti G , Esposito V , Bultrini A , Ferretti E , Santoro A , Faticanti Scucchi L , Gulino A , Cantore G
Published: December 2004

Pituitary tumours are usually benign neoplasia, but may have a locally aggressive or malignant evolution. This study aimed to identify factors which mostly influence their proliferative activity, in order to clarify its value for clinical and research purposes. The proliferative index was determined in a prospective series of 132 pituitary tumours as the percentage of monoclonal antibody MIB-1-immunopositive cells and referred to as the MIB-1 labelling index (LI). Its distribution was analysed according to both univariate and multivariate models. A life-threatening pituitary tumour is presented separately. The mean LI was 1.24+/-1.59%, with significant differences between clinically secreting (CS) and clinically non-secreting (CNS) adenomas. In CS adenomas (n=65), LI was highly variable and markedly influenced by pre-operative pharmacological treatment (0.80+/-1.03 vs 2.06+/-2.39% in treated vs untreated cases, P=0.009); it decreased with patient's age (P=0.025, r=0.28) and increased with tumour volume and invasiveness. The influence of pre-operative treatment and macroscopic features on LI in this group was confirmed by multivariate analysis. In CNS adenomas (n=67), LI distribution was less variable than in CS adenomas (P<0.0001), it was age-independent and correlations with tumour volume, invasiveness or recurrence did not reach significance. In a rapidly growing parasellar tumour, the mean LI was 24% at first surgery and exceeded 50% at second surgery performed 4 months later. LI should be interpreted according to hormone secretion and pre-operative treatment. Unusually high LI values deserve particular attention.
Molecular targets in breast cancer: current status and future directions.
Authors: Cristofanilli M , Hortobagyi G N
Published: December 2004

Our increasing understanding of the pathophysiologic mechanisms of breast carcinogenesis has generated detailed information about the potential roles of specific biomolecular markers in this process. Furthermore, in the last few years the process of targeted drug design has become faster and more sophisticated, providing a variety of agents targeted at these molecules. In this review, we describe the most widely recognized molecular targets in breast cancer.
Sequential steroid hormone receptor measurements in primary breast cancer with and without intervening primary chemotherapy.
Authors: Taucher S , Rudas M , Gnant M , Thomanek K , Dubsky P , Roka S , Bachleitner T , Kandioler D , Wenzel C , Steger G , Mittlb√∂ck M , Jakesz R
Published: December 2004

The objective of this analysis was to determine the accuracy of steroid receptor measurement in large core needle biopsies compared with surgically removed specimens and the influence of preoperative chemotherapy on hormone receptor status. We consecutively performed 722 large core needle biopsies in palpable lesions of the breast. The diagnosis of breast cancer was confirmed upon biopsy in 450 patients; 236 women underwent immediate surgery, and 214 patients received preoperative chemotherapy. We assessed estrogen (ER) and progesterone receptor (PR) in biopsy tissue and surgically removed specimens and calculated accuracy, sensitivity, specificity, the weighted kappa value and Spearman's rank correlation. The modulation of steroid receptor status in preoperatively treated patients was tested by Cochran-Mantel-Haenszel statistics. The accuracy of ER evaluation in the biopsy material of patients without intervening chemotherapy was 91%, sensitivity and specificity were 94% and 80% respectively. Accuracy, sensitivity and specificity were 86% in patients treated preoperatively. In terms of PR assessment, we obtained slightly inferior results: accuracy, sensitivity and specificity were 80%, 73% and 85% respectively in patients without preoperative treatment, and 79%, 48% and 92% respectively in patients undergoing preoperative therapy. Following preoperative chemotherapy, patients showed a significant increase in ER-negative (P=0.02) and PR-negative (P=0.0005) measurements. We have concluded from our results that ER and PR receptor measurement in core needle biopsy is a reliable basis in clinical practice for selecting patients for neoadjuvant endocrine treatment. Preoperative cytotoxic chemotherapy induced a significant extent of variation in the steroid receptor expression of breast cancer cells.
Adaptive hypersensitivity to estrogen: mechanism for superiority of aromatase inhibitors over selective estrogen receptor modulators for breast cancer treatment and prevention.
Authors: Santen R J , Song R X , Zhang Z , Kumar R , Jeng M-H , Masamura S , Yue W , Berstein L
Published: December 2004

Clinical observations suggest that human breast tumors can adapt to endocrine therapy by developing hypersensitivity to estradiol (E(2)). To understand the mechanisms responsible, we examined estrogenic stimulation of cell proliferation in a model system and provided in vitro and in vivo evidence that long-term E(2) deprivation (LTED) causes "adaptive hypersensitivity". The enhanced responses to E(2) do not involve mechanisms acting at the level of transcription of estrogen-regulated genes. We found no evidence of hypersensitivity when examining the effects of E(2) on regulation of c-myc, pS2, progesterone receptor, several estrogen receptor (ER) reporter genes, or c-myb in hypersensitive cells. Estrogen deprivation of breast cells long-term does up-regulate both the MAP kinase and phosphatidyl-inositol 3-kinase pathways. As a potential explanation for up-regulation of these signaling pathways, we found that ERalpha is 4- to 10-fold up-regulated and co-opts a classic growth factor pathway using Shc, Grb-2 and Sos. This induces rapid non-genomic effects which are enhanced in LTED cells. E(2) binds to cell membrane-associated ERalpha, physically associates with the adapter protein SHC, and induces its phosphorylation. In turn, Shc binds Grb-2 and Sos, which results in the rapid activation of MAP kinase. These non-genomic effects of E(2) produce biological effects as evidenced by Elk activation and by morphological changes in cell membranes. Further proof of the non-genomic effects of E(2) involved use of cells which selectively expressed ERalpha in the nucleus, cytosol and cell membrane. We created these COS-1 "designer cells" by transfecting ERalpha lacking a nuclear localization signal and containing a membrane localizing signal. The concept of "adaptive hypersensitivity" and the mechanisms responsible for this phenomenon have important clinical implications. Adaptive hypersensitivity would explain the superiority of aromatase inhibitors over the selective ER modulators (SERMs) for treatment of breast cancer. The development of highly potent third-generation aromatase inhibitors allows reduction of breast tissue E2 to very low levels and circumvents the enhanced sensitivity of these cells to the proliferative effects of E(2). Clinical trials in the adjuvant, neoadjuvant and advanced disease settings demonstrate the greater clinical efficacy of the aromatase inhibitors over the SERMs. More recent observations indicate that the aromatase inhibitors are superior for the prevention of breast cancer as well. These observations may be explained by the hypothesis that estrogens induce breast cancer both by stimulating cell proliferation and by their metabolism to genotoxic products. The SERMs block ER-mediated proliferation only, whereas the aromatase inhibitors exert dual effects on proliferation and genotoxic metabolite formation.
The role of vitamin D and retinoids in controlling prostate cancer progression.
Authors: Peehl D M , Feldman D
Published: December 2004

Prostate cancer is a leading cause of cancer-related deaths in many countries. Premalignant lesions and invasive cancer occur more frequently in the prostate than in any organ other than the skin. Yet, the incidence of clinically detected prostate cancer is much lower than the histopathological incidence. The slow growth of prostate cancer and the low incidence of clinically manifest disease in some geographical locations or racial/ethnic groups suggest that prostate cancer can be controlled, perhaps by dietary factors. Vitamin D and retinoids have emerged as leading candidates both to prevent and to treat prostate cancer. Many of the activities of these compounds, established from epidemiological studies, research with cell culture and animal models, and clinical trials, are consistent with tumor suppressor effects. However, retinoids may have additional tumor enhancer properties that balance or negate anti-cancer activity. This perhaps explains the overall lack of protective effects of vitamin A compounds against prostate cancer found in epidemiological studies, and the minimal efficacy of retinoids in clinical trials to treat prostate cancer. While current efforts focus on developing strategies to use vitamin D compounds to control prostate cancer, the possibility exists that prostate cancer cells may become resistant to tumor suppressor effects of vitamin D. Analyses of experimental model systems show that prostate cancer cells become less sensitive to vitamin D through loss of receptors or signaling molecules that mediate vitamin D's actions, or through changes in metabolic enzymes that synthesize or degrade vitamin D compounds. The potential promise of exploiting vitamin D to control prostate cancer is tempered by the possibility that prostate cancer, perhaps even at early stages, may develop mechanisms to escape tumor suppressor activities of vitamin D and/or retinoids.
Oestrogens and prostate cancer.
Authors: Risbridger G P , Bianco J J , Ellem S J , McPherson S J
Published: December 2004

Androgens are essential for stimulating normal development, growth and secretory activities of the prostate whereas oestrogens are generally regarded as inhibitors of growth. Evidence for the local synthesis of oestrogens includes the detection of aromatase mRNA and protein in the stroma of human non-malignant tissues and in malignant tissue, where it is detected in epithelial tumour cells. As well, aromatase activity was measured by biochemical assay and protein was detected in prostatic non-malignant and tumour cell lines. Taken together with the identification of direct oestrogenic actions on the prostate, these results suggest that alterations in local oestrogen synthesis may have significant consequences in malignancy of these organs. Genetically modified mouse models were studied in order to evaluate the action of oestrogens alone or in combination with androgens on the prostate gland. Hypogonadal (hpg) mice are deficient in gonadotrophins and androgens but showed direct proliferative responses to oestradiol. The responses were characterised by discrete lobe-specific changes including smooth-muscle regression, fibroblast proliferation, inflammation, and basal epithelial cell proliferation and metaplasia. The aromatase knockout (ArKO) mouse, deficient in oestrogens due to a non-functional aromatase enzyme, developed prostatic hyperplasia during the lifelong exposure to elevated androgens, however, no malignant changes were detected in the prostate at any time. In contrast, combined androgen and oestrogen treatment has been shown to induce prostatic dysplasia and adenocarcinoma. These results demonstrate that malignant changes to the prostate gland are dependent upon both androgenic and oestrogenic responses and that neither hormone alone is sufficient to evoke aberrant patterns of growth, resulting in malignancy.
The expression and function of estrogen receptor alpha and beta in human breast cancer and its clinical application.
Authors: Hayashi S-I , Eguchi H , Tanimoto K , Yoshida T , Omoto Y , Inoue A , Yoshida N , Yamaguchi Y
Published: December 2004

The overexpression of estrogen receptor alpha (ERalpha) is frequently observed in the early stage of breast cancer. We previously reported that the specific promoter of the ERalpha gene is responsible for this enhanced transcription of the gene, and identified the cis-acting elements which play an important role in its transcription. Furthermore, methylation of the ERalpha gene promoters also contribute to the regulation of gene transcription. Elucidation of these mechanisms of ERalpha gene expression may provide useful information for the early detection and chemoprevention of breast cancer. On the other hand, the expression of ERbeta has been reported in breast cancer. We have also assessed the significance and function of ERbeta and its variant types in breast cancer, and suggest that ERbeta and ERbetacx specifically suppress the function of ERalpha through different mechanisms. ERbeta isoforms may be important functional modulators of the estrogen-signaling pathway in breast cancer cells, and might affect the clinical outcome of patients. Moreover, to address the role of these ERs on the estrogen-dependent growth of breast cancer cells and to develop a diagnostic tool, we have analyzed the gene expression profiles of estrogen-responsive genes using cDNA microarray. Based on these results, the expression of several candidate genes in breast cancer tissues were analyzed by real-time RT-PCR and by immunohistochemical techniques, in order to discover new predictive factors for the endocrine therapy of patients with breast cancer. These studies could provide new clues for the elucidation of the estrogen-dependent mechanisms of cancer and the clinical benefits for patients.
Androgen receptor involvement in the progression of prostate cancer.
Authors: Suzuki H , Ueda T , Ichikawa T , Ito H
Published: December 2004

Since the growth of prostate cancer is androgen-sensitive, metastatic disease has been treated by hormonal therapy. Almost all prostate cancer patients initially respond to hormonal therapy, but the majority gradually develop resistance. The mechanism of the change in tumors from being androgen-responsive to androgen-unresponsive is generally explained by clonal selection, adaptation, an alternative pathway of signal transduction and androgen receptor (AR) involvement. Since androgen action is mediated by ARs, abnormalities in ARs are believed to play an important role in the progression of prostate cancer. Hyperactivated AR gene mutations have been detected in 20-30% of hormone-refractory tumors and functional analyses have demonstrated a wide responsiveness to estrogens, progesterone and anti-androgens as well as to androgens. The AR is highly amplified in 30% of patients with hormone-refractory prostate cancer that has been treated by castration without anti-androgens. Immunohistochemical studies of ARs in hormone-refractory prostate cancer specimens have shown that AR protein is down-regulated. DNA hypermethylation of the AR promoter region leading to AR down-regulation has been identified in 30% of hormone-refractory prostate cancers. The AR N-terminal domain in the LNCaP cell line model is activated by interleukin-6 via mitogen-activated protein kinase and single transducers and activators of transcription 3. Epidemiological observations have shown that short CAG repeats are more frequently associated with higher transactivational function in the African-American population, which may explain racial differences in the incidence of prostate cancer. Among Japanese, a short CAG repeat appears to predict a response to hormonal therapy, indicating a positive prognostic value and good prognosis at the metastatic stage of prostate cancer. Several co-factors between ARs and the transcriptional complex have been cloned and reports indicate that steroid receptor co-activator 1 is correlated with the hormone-refractory progression of prostate cancer. Thus, ARs plays an important role in the progression of prostate cancer. Based on the findings described above, genetic diagnosis and/or molecular-targeted therapy via AR pathways can be developed for hormone-refractory states.
Parathyroid adenomas and cardiovascular risk.
Authors: Garcia de la Torre N , Wass J A H , Turner H E
Published: December 2004

In recent decades, primary hyperparathyroidism (pHPT) has changed its clinical presentation from a disease with bone and renal involvement to a frequently asymptomatic disorder detected on routine biochemistry. Nevertheless, it remains unclear whether patients with untreated mild asymptomatic hyperparathyroidism are at risk for other complications such as increased morbidity and mortality from cardiovascular diseases. There are limited data on the incidence of cardiovascular abnormalities in mild pHPT. However, pHPT has been associated with increased risk of death from cardiovascular disease, hypertension, left ventricular hypertrophy (LVH), valvular and myocardial calcifications, impaired vascular reactivity, alterations in cardiac conduction, impaired glucose metabolism, dyslipidaemia, and alterations in body composition. The nature of some of these associations is in question, because cure of pHPT does not lead to improvement of the cardiovascular disorder e.g. hypertension. In contrast, currently available data suggest that LVH, impaired glucose metabolism and dyslipidaemia may improve after surgery and that successful parathyroidectomy could decrease the excess mortality in patients with pHPT due to cardiovascular disease.
Interactions between estrogen and insulin-like growth factor signaling pathways in human breast tumor cells.
Authors: Hamelers I H L , Steenbergh P H
Published: December 2004

Estrogens and insulin-like growth factors (IGFs) act as mitogens promoting cell proliferation in normal breast tissue as well as in breast carcinomas. Both hormones have been shown to play a role in the development of breast cancer and were found to activate multiple signaling pathways leading to proliferation of human breast cancer cell lines in vitro. Originally, it was considered that these agents manifest their mitogenic actions through separate pathways, but a growing body of evidence suggests that the IGF- and estrogen-mediated signaling pathways are intertwined. 17beta-Estradiol (E2) has been shown to enhance IGF signaling at multiple levels. E2 treatment of breast cancer cells alters expression of nearly all of the IGF family members including IGF-I, IGF-II, IGF-binding proteins, IGF type I receptor (IGF-RI), and insulin receptor substrate 1. The ligand-bound estrogen receptor has been reported to bind to and to activate the IGF-RI directly. Vice versa, IGF signaling has been reported to enhance estrogen receptor activation in human breast cancer cells by inducing phosphorylation of the estrogen receptor. Finally, several groups have described synergistic effects of the combination of E2 and IGF-I on S phase entry in breast tumor cell lines. Here, we review recent, often contradictory, reports describing the effects of E2 and IGFs on the proliferation of breast tumor cells, with special emphasis on the synergistic effects of the two hormones.
The Kr√ºppel-like transcription factor 6 gene in sporadic pituitary tumours.
Authors: Vax V V , Gueorguiev M , Dedov I I , Grossman A B , Korbonits M
Published: December 2004

The oncogenes and/or tumour suppressor genes which may be involved in the transformation process for the vast majority of pituitary tumours remain unknown. There is substantial evidence for derangement of cell cycle control in such tumours, but cell cycle protein mutations identified in other human malignancies are restricted to only a very small subset of sporadic pituitary neoplasms. Kr√ºppel-like factors are DNA-binding transcriptional regulators with diverse effects including the upregulation of the cell cycle protein p21(WAF1/CIP1). It has been reported that the Kr√ºppel-like transcription factor 6 (KLF6) gene is mutated in a proportion (15-55%) of human prostate cancers, and more recent data are emerging regarding mutated KLF6 in nasopharyngeal carcinomas, astrocytoid gliomas and colorectal cancer. We therefore speculated that other tumours such as pituitary adenomas might also harbour such mutations that may be involved in the control of cell proliferation in the pituitary. The aim of the current study was thus to analyse the KLF6 gene for mutations in sporadic pituitary tumours. We analysed 60 pituitary adenomas (15 GH-, four ACTH-, two PRL-secreting and 39 non-functioning) with direct sequence analysis of exons 2 and 3 of the KLF6 gene, the region where most of the previously described mutations are located. Three non-functioning pituitary adenomas of the 60 pituitary tumours (5%) had two identical sequence changes in exon 2 (missense mutation Val165Met, 523G-->A and a silent substitution in Ser77Ser codon 261C-->T). Analysis of genomic DNA extracted from peripheral lymphocytes in one patient confirmed these changes to be present in the germline and they therefore probably represent polymorphisms, although we cannot exclude the possibility that these are predisposing germline mutations. We conclude that mutations of the KLF6 gene are unlikely to play an important role in sporadic pituitary tumorigenesis.
Hyperfunctioning parathyroid tumours in patients with thyroid nodules. Sensitivity and positive predictive value of high-resolution ultrasonography and 99mTc-sestamibi scintigraphy.
Authors: Lumachi F , Marzola M C , Zucchetta P , Tregnaghi A , Cecchin D , Bui F
Published: December 2004

A series of 112 consecutive patients with primary hyperparathyroidism who underwent both high-resolution neck ultrasonography (US) and 99mTc-sestamibi/99mTc-pertechnetate subtraction scintigraphy (SS) prior to successful parathyroidectomy was reviewed. There were 29 (25.9%) men and 83 (74.1%) women, with a median age of 58 years (range 13-78 years). Patients were divided into two groups, according to the preoperative US findings: group A (87 patients, 77.7%) without thyroid diseases, and group B (25 patients, 22.3%) with either multinodular goitre or a solitary nontoxic thyroid nodule. In group B patients partial or total thyroidectomy was also performed, according to the intraoperative findings and frozen-section examination results. Final histopathology showed 99 (88.4%) solitary parathyroid (PT) adenomas and 3 (2.7%) PT carcinomas, while 10 (8.9%) patients had a multiglandular disease. The sensitivity and positive predictive value (PPV) were (group A vs group B) 79.8% vs 70.8% (P=0.25) and 95.7% vs 94.4% (P=0.58) for US, and 83.3% vs 87.0% (P=0.47) and 95.9% vs 90.9% (P=0.32) for SS respectively. Better but similar (P=not significant) results were obtained in patients with solitary PT tumours: 81.5% vs 77.8% (US) and 85.0 vs 94.1% (SS) sensitivity; 97.1% vs 93.3% (US) and 95.8% vs 88.9% (SS) PPV. Overall, the combination of US and SS was 92.9% sensitive (group A=93.1%, group B=92.0%; P=0.55), and the PPV reached 100% in each group. In conclusion, in patients with primary hyperparathyroidism the results of both US and SS are independent of coexistent thyroid disease, especially in patients with solitary PT tumours.
Surgery for midgut carcinoid.
Authors: Sutton R , Doran H E , Williams E M I , Vora J , Vinjamuri S , Evans J , Campbell F , Raraty M G T , Ghaneh P , Hartley M , Poston G J , Neoptolemos J P
Published: December 2004

Many clinicians prefer to avoid surgery in patients with carcinoid neoplasia, because of its slow growth and relatively favourable prognosis. Nevertheless, the commonest cause of death in patients with carcinoid is advanced metastatic disease, and both clinical and epidemiological data indicate that the more effectively the disease is ablated, the more long-lasting the benefit. Multidisciplinary management of patients with carcinoid must consider inherited risk, possible multiple carcinoids and/or synchronous non-carcinoid cancer, and the use of a range of investigations that also evaluate the 10% of patients with carcinoid syndrome with or without valvular heart disease. Although primary size is correlated with the presence of nodal with or without liver metastases, carcinoid tumours <1 cm in diameter may be metastatic at presentation, particularly those arising within the small intestine. In the jejunum and ileum, resection of all sizes of carcinoid with local and regional nodes is preferred, to prevent nodal dissemination causing mesenteric ischaemia with or without infarction. Resection of nodal metastases should be undertaken in those with persistent or recurrent nodal disease if possible. Appendiceal and right colonic carcinoids are most effectively treated by right hemicolectomy with local and regional nodal clearance, as for adenocarcinoma. However, for most appendiceal carcinoids which are <1 cm in diameter and non-invasive, appendicectomy alone is sufficient. For appendiceal carcinoids 1-2 cm in diameter, histopathological assessment helps to determine the need for hemicolectomy. Liver resection has been followed by prolonged 5 year survival in several series and is recommended in appropriate patients to attempt cure or to debulk metastatic disease. Liver transplantation has had only qualified success in highly selected patients without extra-hepatic disease in whom other therapies have failed.
Carcinoid case presentation and discussion: the American perspective.
Authors: Warner R R P
Published: December 2004

The rationale underlying an aggressive approach in the management of some carcinoid patients is explained and illustrated by the presented case of a middle-aged man with advanced classic typical midgut carcinoid. The patient exhibited somatostatin receptor scintigraphy-positive massive liver metastases, carcinoid syndrome, severe tricuspid and pulmonic cardiac valve disease with congestive heart failure, ascites and malnutrition. He had been treated for several years with supportive medications and biotherapy including octreotide and alpha interferon but his tumor eventually progressed and his overall condition was markedly deteriorated when he first sought more aggressive treatment. This consisted of prompt replacement of both tricuspid and pulmonic valves, followed by hepatic artery chemoembolus (HACE) injection and then surgical tumor debulking including excision of the primary tumor in the small intestine. In addition, radiofrequency ablation was utilized to reduce the volume of metastases in the liver. Prophylactic cholecystectomy was also performed and a biopsy of tumor was submitted for cell culture drug resistance testing. This was followed by systemic chemotherapy utilizing the drug (docetaxel) which the in vitro studies suggested as most likely to be effective. His excellent response to this succession of treatments exemplifies the successful application of aggressive sequential multi-modality therapy.