Biomedical subjects

Shuk-Mei Ho

Publications and source records attributed to Shuk-Mei Ho.

32 records · Page 2Linked to original sources

PubMed2003

Estrogen receptor-beta expression in human testicular germ cell tumors.

PURPOSE: Estrogen exposure has been linked to a risk for the development of testicular germ cell cancers. The effects of estrogen are now known to be mediated by estrogen receptor (ER)-alpha and -beta receptor subtypes, but only ER-beta has been found in human normal testis. The goal of the present study was to compare the localization and expression levels of these ER subtypes in testicular germ cell cancers (seminomas and nonseminomatous germ cell tumors) with normal testis. For completeness, expression of androgen and progesterone receptors was also investigated. EXPERIMENTAL DESIGN: Immunohistochemistry was used to localize the expression of steroid receptors in 39 archival testicular germ cell cancers and 5 morphologically normal testes. Expression of the steroid receptors at the transcript level was semiquantified by reverse transcription-PCR in 5 paired fresh-frozen specimens of normal and neoplastic testes. RESULTS: ER-alpha was not expressed in the human normal testis. It was also absent in all of the testicular germ cell cancers studied. In contrast, ER-beta was strongly expressed in various germ cells of the normal testis. However, its expression was markedly diminished in seminomas, embryonal cell carcinomas, and in mixed germ cell tumors, at both transcriptional and translational levels. In contrast, ER-beta remained highly expressed in endodermal sinus tumors and teratomas. Progesterone receptor, an estrogen-regulated gene, was localized to spermatagonia of the normal testis, but its expression dramatically reduced in seminomas. With the exception of spermatagonia, androgen receptor was found in all of the germ cells of the normal testis, but, aside from trace staining in 3 of 5 endodermal sinus tumor cells, it was not detected immunohistochemically in any other germ cell cancer. CONCLUSIONS: We confirm expression of ER-beta, but not ER-alpha, in normal testicular cells, suggesting that only the former ER subtype mediates the action of estrogen in the human male gonad. Our results provide the first evidence that only ER-beta is expressed in testicular germ cell tumors. Its expression is down-regulated in seminomas and embryonal cell carcinomas but remains high in endodermal sinus tumors and in teratomas. The observed differences in ER-beta expression levels among different testicular germ cell tumors may reflect divergent pathways of differentiation/dedifferentiation of these neoplasms from a common precursor. Collectively, these findings provide a possible mechanistic link between estrogen exposure and testicular cancer risk.

Adult↗

PubMed2003

Profiling follicle stimulating hormone-induced gene expression changes in normal and malignant human ovarian surface epithelial cells.

Epidemiological data have implicated the pituitary gonadotropin follicle stimulating hormone (FSH) as both a risk factor for and a protective agent against epithelial ovarian cancer. Yet, little is known about how this hormone could play such opposing roles in ovarian carcinogenesis. Complementary DNA microarrays containing 2400 named genes were used to examine FSH-induced gene expression changes in ovarian cancer (OC) and immortalized normal human ovarian surface epithelial (HOSE) cell lines. Two-way t-statistics analyses of array data identified two distinct sets of FSH-regulated genes in HOSE and in established OC cell lines established from patients (OVCA cell lines). Among the HOSE cell lines, FSH increased expression of 57% of the 312 genes and downregulated 43%. In contrast, FSH diminished expression of 92% of the 177 genes in the OVCA cell lines. All but 18 of the genes affected by FSH in HOSE cell lines were different from those altered in OVCA cell lines. Among the 18 overlapping genes, nine genes exhibited the same direction of change following FSH challenge, while the other nine showed discordance in response between HOSE and OVCA cell lines. The FSH-induced differential expression of seven out of nine genes was confirmed by real-time RT-PCR. Gene-specific antisense oligonuleotides (ODNs) were used to inhibit the expression of genes encoding GTPase activating protein (rap1GAP), neogenin, and restin in HOSE and OVCA cells. Antisense ODNs to neogenin and restin, but not an antisense ODN to rap1GAP, were effective in inhibiting OVCA cell growth, diminishing proliferating cell nuclear antigen expression, and increasing caspase 3 activities. Furthermore, the ODN to rap1GAP was further shown to be ineffective in altering migration properties of OVCA cell lines. HOSE cell proliferation was not affected by treatment with any of the antisense ODNs. In summary, gene profiling data reveal for the first time that FSH may exert different biological actions on OVCA cells than on HOSE cells, by differential regulation of a set of putative oncogenes/tumor suppressors. Specifically, neogenin and restin were found to exhibit proproliferation/survival action on OC cells.

Adenosine Triphosphate↗

PubMed2003

Expression study of three secretory proteins (prostatic secretory protein of 94 amino acids, probasin, and seminal vesicle secretion II) in dysplastic and neoplastic rat prostates.

BACKGROUND: Prostatic secretory protein of 94 amino acids (PSP94), probasin, and seminal vesicle secretion II (SVSII) are the three major proteins secreted by the lateral lobe of the rat prostate gland. Among these proteins, rodent PSP94 but not probasin and SVSII has a human homologue and it is also a major secretory protein of the human prostate, in addition to prostatic acid phosphatase and prostate-specific antigen. METHODS: In this study, we examined and compared the mRNA expression of these three secretory markers in three rat models of prostate cancer including the sex steroid-induced dysplasia (prostatic intraepithelial neoplasia or PIN) in Noble (Nb) rat model, an androgen-independent Nb rat prostatic tumor (AIT) and Dunning rat prostatic adenocarcinomas (both androgen-dependent and -independent) by in situ hybridization (ISH), reverse transcriptase-polymerase chain reaction (RT-PCR), and immunohistochemistry. RESULTS: The transcripts for the three markers were highly expressed in the secretory epithelium of normal lateral prostate (LP). Their hybridization signals became reduced in the epithelial cells in the low-grade PINs and significantly weakened or lost in the high-grade PINs induced in the LP. Interestingly, we observed that some dysplastic cells located at the basal compartment of the PIN lesions, and nests of outpouching epithelial cells in the vicinity of PINs, expressed positive hybridization signals of three markers. In the adenocarcinoma, signals of probasin but not PSP94 and SVSII were detected. No hybridization signals were detected in both Dunning and AIT tumors. By RT-PCR, transcripts for these proteins were still detected but significantly reduced in the Dunning tumors, whereas in the AIT tumor, only SVSII transcripts were detected. Immunohistochemistry of PSP94 also showed a reduced staining in the PIN lesions, but no immunoreactivity was seen in the rat prostatic tumors. CONCLUSIONS: The mRNA expression of the three prostatic secretory markers were decreased in the hormone-induced PINs and in two rat prostatic tumors, indicating that the androgen-regulated secretory differentiation was impaired during the development of the premalignant lesion and further reduced in advanced tumors. The abnormal expression pattern of these secretory markers and androgen receptor (AR) in the basal compartment of the PIN lesions suggests that there is a population of cell types with secretory phenotype appearing in the basal cell layer during the early malignant transformation of the prostatic epithelium.

Adenocarcinoma↗

PubMed2003

Sex hormone-induced alterations in the activities of antioxidant enzymes and lipid peroxidation status in the prostate of Noble rats.

BACKGROUND: Oxidative stress has been implicated in prostate carcinogenesis. In the Noble rat model, treatment of rats with testosterone (T) plus 17beta-estradiol (E(2)) induced dysplasia and adenocarcinoma. Previous reports from us and other have indicated a linkage between steroid hormones and oxidative status in prostate cells in vivo and in vitro. Here, we provide further evidence that androgens and estrogens could induce a lobe-specific shift of prooxidant-antioxidant balance and alterations in antioxidant enzyme activities, leading to oxidative stress in the rat prostate gland in vivo. METHODS: Male Noble rats were subjected to single (T, E(2), or diethylstilbestrol [DES] alone) or combined (T + E(2) or T + DES) hormone treatments. Lipid peroxidation status and antioxidant enzyme activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD) were assayed spectrophotometrically. RESULTS: Treatment of rats with T did not alter lipid peroxidation in either the ventral prostate (VP) or the dorsolateral prostate (DLP). In contrast, exposure of rats to DES or E(2) modestly elevated lipid peroxidation in rat VP or DLP, respectively. Of importance, T + DES and T + E(2) treatments of rats induced marked increases in lipid peroxidation in the VP and the DLP, respectively. Antioxidant enzyme activities in the VP and DLP exhibited differential responses to sex hormone challenges. The activities of catalase, GPx, GR, and G6PD were mostly suppressed in either single or dual hormone-treated DLP, whereas there is a general increase of GR and G6PD activities in the VP after hormonal exposures. The changes in T + DES-treated VP were most dramatic with a marked activation of GPx (by one-fold), GR (by one-fold), and G6PD (by five-fold). CONCLUSION: The lobe-specific differential responses of hormone-induced oxidative stress and modulations of antioxidant enzymatic defenses in the rat prostate suggest that reactive oxygen species may play a role in hormone-induced prostate carcinogenesis.

Animals↗

PubMed2003

Androgenic regulation of oxidative stress in the rat prostate: involvement of NAD(P)H oxidases and antioxidant defense machinery during prostatic involution and regrowth.

Little is known about the roles of androgens in the regulation of redox state in the prostate, a cellular process believed to profoundly influence normal and aberrant prostate functions. We demonstrate that castration induced discrete oxidative stress (OS) in the acinar epithelium of rat ventral prostate (VP), as evident from marked increases in 8-hydroxy-2'-deoxy-guanosine and 4-hydroxynonenal protein adducts in the regressing epithelium. Testosterone replacement partially reduced OS in VP epithelia of castrates, but the level remained higher than in intact rats. Quantification of steady-state mRNA levels of 14 genes involved in the anabolism and catabolism of reactive oxygen species (ROS) showed that castration resulted in dramatic increases of three ROS-generating NAD(P)H oxidases (Noxs) including Nox1, gp91(phox), and Nox4, significant reductions of key ROS-detoxifying enzymes (superoxide dismutase 2, glutathione peroxidase 1, thioredoxin, and peroxiredoxin 5), and unchanged levels of catalase, glutathione reductase, gamma-glutamyl transpeptidase, and glutathione synthetase. Testosterone replacement in castrated rats partially reduced expression of Noxs but restored expression of superoxide dismutase 2, glutathione peroxidase 1, thioredoxin, and peroxiredoxin 5 to complete normalcy and induced a compensatory increase in expression of catalase, glutathione reductase, gamma-glutamyl transpeptidase, and glutathione synthetase in the regenerating VP. Expression of superoxide dismutase 1, glutathione S-transferase-pi, and glucose-6-phosphate dehydrogenase was unaffected by castration and testosterone replacement. These findings indicate androgen-deprivation induces OS in the rat VP through elevation of ROS anabolism and diminution of antioxidant detoxification. Androgen replacement partially reduces OS in rat VP to precastration levels. Expression of Noxs remained high amid a broad-based recovery of antioxidant defense mechanism(s). These data might have implications on the use of androgen blockade for prostate cancer prevention and androgen therapy for andropause treatment in elderly men.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2003

Alpha-methylacyl-CoA racemase (P504S) expression in evolving carcinomas within benign prostatic hyperplasia and in cancers of the transition zone.

Carcinomas of the transition zone (TZ) constitute approximately 20% of all prostate cancers. The TZ is the site of origin of grade 1 and grade 2 cancers, the most well-differentiated of the Gleason grade tumors, as well as for benign prostatic hyperplasia (BPH). In this regard, grade 1 carcinoma has architectural features that closely mimic gland-rich BPH nodules. Although a relationship between cancers arising in this zone and BPH has been suspected, such an association remains undefined. To gain insight into the origin, development, and progression of cancers arising in the TZ, we used a highly specific rabbit monoclonal antibody (P504S) directed against alpha-methylacyl-CoA racemase (AMACR) to study the expression of the enzyme in 25 cases of evolving and fully developed carcinomas of this zone. AMACR has been proposed as a new molecular marker for prostate cancer, because the enzyme is reportedly overexpressed in high-grade dysplasias, also termed prostatic intraepithelial neoplasia, a purported precursor of prostatic carcinoma, and in all grades of prostatic carcinoma of the peripheral zone. Using P504S, P63, or antikeratin 34beta E12 antibodies, we found it possible to define areas of transition from hyperplasia to carcinoma in 6 BPH nodules. In 3 other cancer-containing BPH nodules, staining for AMCAR was observed in benign hyperplastic glands that were juxtaposed to carcinoma. Enzyme expression was also evident in 5 additional cases in which BPH was found adjacent to cancer. In contrast; AMACR was not visualized in any other BPH nodules that we studied. Thus, using the enzyme as a marker, we document for the first time that some carcinomas of the TZ arise from an AMCAR-positive transition lesion within a subset of BPH nodules. Moreover, the finding of enhanced AMACR expression in benign glands within cancer-containing nodules as well as in BPH lesions adjacent to carcinoma suggests that in some cases, up-regulation of the enzyme may precede morphological evidence of neoplastic transformation. AMACR was lightly expressed in transition lesions and grade 1 carcinomas but more strongly expressed in higher-grade TZ cancers, suggesting that enzyme expression is enhanced with progression in this zone. Because AMACR is involved in the beta oxidation of branched fatty acids and their derivatives, enhanced expression of the enzyme in evolving carcinomas in BPH nodules, as well as its up-regulation in juxtaposed morphologically benign glands and grade 1 carcinomas, suggests that increased utilization of fatty acids may play an important role in carcinoma development and progression in the TZ.

Antibodies, Monoclonal↗

PubMed2003

Age-associated changes in histology and gene-expression profile in the rat ventral prostate.

The incidence of prostate diseases rises dramatically with age in men, yet little is understood of the mechanisms underlying prostatic senescence and its contribution to disease development in the gland. In Noble rats, aging of the ventral prostate (VP) is characterized morphologically by widespread atrophy of acini, increased accumulation of concretions in glandular lumen, infiltration of inflammatory cells, and focal epithelial atypia. We used a cDNA microarray containing 2388 known transcripts, together with the Tyramide Amplification System and t statistics, to identify differentially expressed genes in the VPs of young (3 months old) and old (16 months old) rats. A total of 78 VP genes were found to be differentially expressed by the two groups; in old rats, 65 VP genes (83%) showed reduced expression and 13 genes (17%) showed increased expression compared with young animals. The age-dependent underexpressed genes fell into several functional clusters: those involved in amino-acid metabolism, protein synthesis, protein secretion and degradation, vesicle/membrane trafficking, energy metabolism, signal transduction, spermidine and spermine syntheses, and cellular defense against stress. The overexpressed genes included iduronate 2-sulfatase, HLA class I locus C heavy chain, membrane cofactor protein of the complement system, TRPM-2, cadherin-associated protein-related, and X-CGD. Post hoc analyses confirmed a progressive decline in the expression of ribophorin II and BiP and a gradual increase in the expression of TRPM-2 in rat VPs as animals aged from 3 to 19 months old. In conclusion, the observed widespread declines in expression of genes involved in protein synthesis, protein fidelity maintenance, anabolism, growth inhibition, and energy metabolism, together with increased expression of genes implicated in cell survival in the VPs of senescent rats, may help explain the susceptibility of the prostates of elderly men to development of disease.

Age Factors↗

PubMed2003

Branched fatty acids in dairy and beef products markedly enhance alpha-methylacyl-CoA racemase expression in prostate cancer cells in vitro.

An enzyme previously identified as alpha-methylacyl-CoA racemase (AMACR) is overexpressed in high-grade prostatic intraepithelial neoplasia and in a majority (60-100%) of prostate cancers (CaPs) as compared with normal and benign hyperplastic lesions of the prostate, where it is minimally expressed. This enzyme is required for the beta-oxidation of branched-chain fatty acids, which include phytanic acid and its alpha-oxidation product, pristanic acid. Interestingly, there is an established correlation between CaP risk and the consumption of dairy and beef products, which also contain marked quantities of these two phytols. In this context, it has also been reported that sex steroids influence lipogenesis through the induction of fatty acid synthase in CaP-derived cell lines and CaP tissues. These findings indicate a potential role for AMACR and the possible influence of sex steroids in both the early development and subsequent progression of CaP. Despite the recent interest in AMACR as a histological marker for CaP, little is known about the regulation of this enzyme and its role in CaP development. To identify potential AMACR-regulating factors, we treated LNCaP cells (an androgen-responsive CaP-derived cell line) and NPrEC cells (a normal prostate basal epithelial cell line) with increasing concentrations of pristanic acid, phytanic acid, 5alpha-dihydrotestosterone, and 17beta-estradiol. Neither the biologically potent androgen 5alpha-dihydrotestosterone nor 17beta-estradiol had any apparent effect on AMACR expression at the protein or transcriptional levels in either cell line. Conversely, pristanic acid and, to a much lesser extent, phytanic acid markedly increased AMACR protein levels selectively in the LNCaP cell line, but not the NPrEC cell line. However, no change was measured at the transcriptional level in either cell line. AMACR is therefore significantly increased at the protein level in CaP cells, through what appears to be the stabilizing effect of the same fatty acids that are present at appreciable concentrations in beef and dairy products, which have been associated with CaP risk. Our findings therefore provide a link between the consumption of dietary fatty acids and the enhanced expression of AMACR, an enzyme that may play an important role in genesis and progression of CaP.

5-alpha-Dihydroprogesterone↗

PubMed2002

Expression of estrogen receptor beta in the fetal, neonatal, and prepubertal human prostate.

BACKGROUND: Although androgens have long been implicated in the development, regulation, and pathophysiology of the prostate, evidence suggests that estrogens may also affect these processes. Specifically, estrogens have been shown to influence the development of the fetal and neonatal rodent prostate and to induce a pathognomonic change, termed squamous metaplasia, in the developing and adult prostate. Studies have been inconclusive, however, as to whether estrogens enhance or restrain the growth of the gland. Although the fetal rodent prostate has been reported to contain both estrogen receptor alpha (ER-alpha) and beta (ER-beta), there have been no reports as to whether either of the ER subtypes is expressed in the developing human prostate. METHODS: In the present study, we used a novel antibody, directed against a unique sequence in the F domain of ER-beta, and laser capture microdissection/reverse transcriptase-polymerase chain reaction to study the expression of the receptor in the fetal, neonatal, and prepubertal human prostate. Results were compared with the expression of ER-alpha, androgen receptor (AR), prostatic acid phosphatase (PAP), prostate specific antigen (PSA), high molecular weight cytokeratin (HMCK), and the proliferative marker Ki67. RESULTS: For the first time, we report that ER-beta is the only estrogen receptor detected at the protein level in the morphologically normal developing human fetal prostate. By midgestation, strong immunostaining for ER-beta was detected in the nuclei of nearly 100% of epithelial and in the majority of stromal cells. This pattern of expression was evident in the fetal, neonatal, and early prepubertal prostate. However, by 11 years postnatal, staining for the receptor became restricted primarily to the basal epithelial and stromal compartments, a pattern analogous to that observed in the normal adult gland. ER-alpha mRNA was present in microdissected stroma of the fetal gland. Although ER-alpha was not immunodetected in any morphologically normal fetal epithelial or stromal cells, weak staining for the receptor, however, was found in some examples of squamous metaplasia, suggesting the role of alpha-subtype in this lesion. ER-alpha was clearly visualized immunohistochemically at 1 month of postnatal development where it was then localized exclusively in periacinar stromal nuclei, which suggests that it may exert paracrine influences on further prostatic glandular development. Interestingly, the expression of ER-beta early in prostatic development occurred coincident with both the increasing rate of epithelial cell proliferation, observed in the first half of gestation, and the reported high levels of estrogen in the gland from midgestation until term. Paradoxically, however, staining for the receptor remained intense, despite the dramatic decrease in Ki67 labeling observed in the second half of gestation. CONCLUSION: Our results indicate that the effects of estrogens on the growth of the human fetal prostate are mediated primarily by ER-beta but that ER-alpha contributes to postnatal glandular development. Furthermore, these results suggest that ER-beta, possibly in concert with androgens, may mediate diverse effects on prostate epithelial proliferation by first promoting cell expansion early in gestation, and then acting to limit growth later in prostatic development.

Acid Phosphatase↗

PubMed2002

Reproductive hormone-induced, STAT3-mediated interleukin 6 action in normal and malignant human ovarian surface epithelial cells.

BACKGROUND: Reproductive hormones are associated with risk for epithelial ovarian cancer. To determine the effect of such hormones on the activation of interleukin 6 (IL-6)/STAT3 (signal transducer and activator of transcription-3) signaling, which may be involved in ovarian cancer, we investigated the status of STAT3, IL-6, and its receptor in immortalized human ovarian surface epithelial (HOSE) and ovarian cancer (OVCA) cell lines. METHODS: Two immortalized HOSE cell lines and two OVCA cell lines were cultured with gonadotropins, sex steroid hormones, and/or IL-6, alone or with specific inhibitors or IL-6-neutralizing antibodies. Expression of IL-6, the IL-6 receptor alpha chain (IL-6Ralpha), and phosphorylated and unphosphorylated STAT3 messenger RNAs (mRNAs) and proteins in all cells was determined. Cell proliferation and soft-agar colony formation were assessed. STAT3 activity was investigated in OVCA cells transfected with a dominant negative STAT3 (Dn-STAT3), wild-type STAT3, or an empty control vector. All statistical tests were two-sided. RESULTS: Levels of IL-6 mRNA and protein increased in all cells treated with follicle-stimulating hormone (FSH), luteinizing hormone (LH), 17beta-estradiol, or estrone but increased only in OVCA cells treated with testosterone and 5alpha-dihydrotestosterone. For all lines, IL-6 antibodies partially inhibited hormone-stimulated cell proliferation but completely inhibited IL-6-enhanced cell proliferation. IL-6 induced STAT3 phosphorylation and activation in HOSE cells; STAT3 was constitutively activated in OVCA cells. Higher levels of IL-6Ralpha and STAT3 transcription factors were observed in OVCA cells than in HOSE cells. After transfection, Dn-STAT3 suppressed endogenous STAT3 and inhibited all forms of IL-6-stimulated OVCA cell proliferation (OVCA 429 cells, P<.001; OVCA 432 cells, P<.006), whereas wild-type STAT3 enhanced HOSE cell proliferation (wild-type STAT3 at 0.5 microg/mL in HOSE 306 cells, P<.002; STAT3 at 1.0 microg/mL in HOSE 306 or both concentrations of wild-type STAT3 in HOSE 642 cells, P<.001). CONCLUSIONS: The IL-6/STAT3 signaling pathway may mediate FSH-, LH-, and estrogen-stimulated HOSE cell proliferation. Increased IL-6Ralpha expression and constitutive STAT3 activation may be associated with ovarian cancer.

Adult↗

PubMed2002

Ribozyme-mediated downregulation of human metallothionein II(a) induces apoptosis in human prostate and ovarian cancer cell lines.

Human metallothioneins (MTs) are low-molecular-weight, cysteine-rich, metal ion-binding proteins that constitute the majority of intracellular protein thiols. They are overexpressed in prostate and ovarian cancers and are believed to confer resistance to radiation and cytotoxic anticancer drugs. The aim of this study was to investigate the roles of MTs in prostate and ovarian cancer cells and their possible relationship with other cancer development and progression factors. The main problem in investigating the role of MT, however, is the absence of any known specific inhibitor. To this end, in a previous study, we had developed sequence-specific ribozymes (Rzs) targeting MT and had shown their in cellulo efficacy. Here we show that transient transfection of a vector carrying a hammerhead Rz (Rz4-9), designed to cleave class II MT, in the human prostate cancer cell line PC-3 and the ovarian cancer cell line SKOV-3 resulted in a dose-dependent attenuation of MT-II(a) transcripts and dramatic cell loss. Transient transfection with 2 microg of Rz4-9 vector DNA completely abolished MT-II(a) mRNA levels and induced a 94% and a 67% reduction in cell number in PC-3 cells and SKOV-3 cells, respectively. Fluorescence-activated cell sorting (FACS) showed that the Rz-induced cell loss probably was due to apoptosis, because it was associated with marked increases in the hypodiploid cell population, reaching maximums of 52% and 64% in cultures of PC-3 and SKOV-3, respectively. Additionally, annexin V-propidium iodide double-staining, followed by FACS, confirmed that Rz4-9-induced cell death was due to apoptosis and showed a vector DNA-dependent increase in late apoptotic cell numbers that reached maximums of 80% and 42%, respectively, in PC-3 and SKOV-3 cell cultures transfected with the highest concentration of vector DNA. In parallel experiments, transfection with a vector containing the enzymatically inactive mutant Rz-3-3 or the empty vector was not effective in inducing similar responses. The Rz-induced loss of MT-II(a) mRNA-associated cell death in these cancer cell lines was attended by dose-dependent downregulation of the proto-oncogene c-myc and the apoptosis inhibitory mediator bcl-2, suggesting that these signaling pathways are involved in the process. In conclusion, our data indicate that MT-II(a) is an important cell-survival or anti-apoptotic factor for prostate and ovarian cancer cells and that downregulation of its expression via transgene expression of a sequence-specific Rz is a feasible target for cancer therapy.

Apoptosis↗

PubMed2002

DNA microarrays in prostate cancer.

DNA microarray technology provides a means to examine large numbers of molecular changes related to a biological process in a high throughput manner. This review discusses plausible utilities of this technology in prostate cancer research, including definition of prostate cancer predisposition, global profiling of gene expression patterns associated with cancer initiation and progression, identification of new diagnostic and prognostic markers, and discovery of novel patient classification schemes. The technology, at present, has only been explored in a limited fashion in prostate cancer research. Some hurdles to be overcome are the high cost of the technology, insufficient sample size and repeated experiments, and the inadequate use of bioinformatics. With the completion of the Human Genome Project and the advance of several highly complementary technologies, such as laser capture microdissection, unbiased RNA amplification, customized functional arrays (eg, single-nucleotide polymorphism chips), and amenable bioinformatics software, this technology will become widely used by investigators in the field. The large amount of novel, unbiased hypotheses and insights generated by this technology is expected to have a significant impact on the diagnosis, treatment, and prevention of prostate cancer. Finally, this review emphasizes existing, but currently underutilized, data-mining tools, such as multivariate statistical analyses, neural networking, and machine learning techniques, to stimulate wider usage.

Algorithms↗

PubMed2002

Gene expression profiling of testosterone and estradiol-17 beta-induced prostatic dysplasia in Noble rats and response to the antiestrogen ICI 182,780.

We previously demonstrated that 1) treatment of Noble rats for 16 wk with testosterone (T) and estradiol-17 beta (E2) led to 100% incidence of dorsolateral prostate (DLP) dysplasia and hyperprolactinemia and 2) blockade of PRL release with bromocriptine cotreatment significantly lowered the incidence of DLP dysplasia. In the current study, we sought to determine whether E2 exerts direct effects, independent of PRL, in this model system. The pure antiestrogen ICI 182,780 (ICI), reported to have no effect on PRL release in female rats, was administered biweekly to T + E2-treated rats at 3 mg/kg body weight. ICI cotreatment completely prevented DLP dysplasia development but it also blocked hyperprolactinemia in the dual hormone-treated rats. Gene profiling with an 1185 gene rat cDNA array identified approximately 100 genes displaying > or = 3-fold changes in rat lateral prostates (LPs) following T + E2 treatment. Significantly more genes were up-regulated (77) than down-regulated (14), reflecting cellular/molecular changes associated with enhanced cell proliferation, DNA damage, heightened protein and RNA synthesis, increased energy metabolism, and activation of several proto-oncogenes and intracellular signaling pathways. Post hoc analyses, using quantitative real-time RT-PCR, corroborated differential expression of eight genes, exhibiting three different patterns of altered expression. Genes encoding the early growth response protein 1 and metalloendopeptidase meprin beta-subunit were similarly altered in T + E2- and T + E2 + ICI-treated animals when compared with untreated controls. In contrast, transcripts of fos-related antigen-2, growth arrest and DNA damage-inducible protein-45, and signal transducer and activator of transcription-3 were significantly increased in the LPs of T + E2-treated animals, but the increases were reversed by cotreatment with ICI. Differential expression of fos-related antigen-2 and growth arrest and DNA damage-inducible protein-45 were further confirmed at the protein level by immunohistochemistry. Lastly, levels of A-RAF, VIP-1 receptor, and calpastatin mRNA were distinctly lessen in rat LPs under T + E2 influence, but rebound with ICI cotreatment. In conclusion, our findings further implicated pituitary PRL in the induction of dysplasia in rat LP. Gene profiling provided clues that molecular events related to enhancement of cell proliferation, DNA damage, and activation of proto-oncogenes and transforming factors may be causally linked to the genesis of LP dysplasia in this rat model.

Adenosine Triphosphatases↗

PubMed2002

Summary of the National Toxicology Program's report of the endocrine disruptors low-dose peer review.

At the request of the U.S. Environmental Protection Agency (U.S. EPA), the National Toxicology Program organized an independent and open peer review to evaluate the scientific evidence on low-dose effects and nonmonotonic dose-response relationships for endocrine-disrupting chemicals in mammalian species. For this peer review, "low-dose effects" referred to biologic changes that occur in the range of human exposures or at doses lower than those typically used in the standard testing paradigm of the U.S. EPA for evaluating reproductive and developmental toxicity. The demonstration that an effect is adverse was not required because in many cases the long-term health consequences of altered endocrine function during development have not been fully characterized. A unique aspect of this peer review was the willing submission of individual animal data by principal investigators of primary research groups active in this field and the independent statistical reanalyses of selected parameters prior to the peer review meeting by a subpanel of statisticians. The expert peer-review panel (the panel) also considered mechanistic data that might influence the plausibility of low-dose effects and identified study design issues or other biologic factors that might account for differences in reported outcomes among studies. The panel found that low-dose effects, as defined for this review, have been demonstrated in laboratory animals exposed to certain endocrine-active agents. In some cases where low-dose effects have been reported, the findings have not been replicated. The shape of the dose-response curves for reported effects varied with the end point and dosing regimen and were low-dose linear, threshold-appearing, or nonmonotonic. The findings of the panel indicate that the current testing paradigm used for assessments of reproductive and developmental toxicity should be revisited to see whether changes are needed regarding dose selection, animal-model selection, age when animals are evaluated, and the end points being measured following exposure to endocrine-active agents.

Androgens↗