New antiprogestins with partial agonist activity: potential selective progesterone receptor modulators (SPRMs) and probes for receptor- and coregulator-induced changes in progesterone receptor induction properties

A pharmacologically relevant property of steroid hormone-regulated gene induction is the partial agonist activity of antisteroid complexes. We now report that dexamethasone-mesylate (Dex-Mes) and dexamethasone-oxetanone (Dex-Ox), each a derivative of the glucocorticoid-selective steroid dexamethasone (Dex), are two new antiprogestins with significant amounts of agonist activity with both the A and B isoforms of progesterone receptor (PR), for different progesterone-responsive elements, and in several cell lines. These compounds continue to display activity under conditions where another partial antiprogestin (RTI-020) is inactive. These new antiprogestins were used to determine whether the partial agonist activity of PR complexes can be modified by changing concentrations of receptor or coregulator, as we have recently demonstrated for glucocorticoid receptors (GRs). Because GR and coregulator concentrations simultaneously altered the position of the physiologically relevant dose-response curve, and associated EC(50), of GR-agonist complexes, we also examined this phenomenon with PR. We find that elevated PR or transcriptional intermediary factor 2 (TIF2) concentrations increase the partial agonist activity of Dex-Mes and Dex-Ox, and the EC(50) of agonists, independently of changes in total gene transactivation. Furthermore, the corepressors SMRT (silencing mediator for retinoid and thyroid receptors) and NCoR (nuclear receptor corepressor) each suppresses gene induction but NCoR acts opposite to SMRT and, like the coactivator TIF2, reduces the EC(50) and increases the partial agonist activity of antiprogestins. These comparable responses of GR and PR suggest that variations in receptor and coregulator concentrations may be a general mechanism for altering the induction properties of other steroid receptors. Finally, the magnitude of coregulator effects on PR induction properties are often not identical for agonists and the new antagonists, suggesting subtle mechanistic differences. These properties of Dex-Mes and Dex-Ox, plus the sensitivity of their activity to cellular differences in PR and coregulator concentrations, make these steroids potential new SPRMs (selective progesterone receptor modulators) that should prove useful as probes of PR induction properties.

Ethical issues in community-based cancer control: considerations in designing interventions

Intervention studies are essential in the drive to reduce the burden of cancer in the United States. The means to accomplish primary and secondary cancer prevention is possible through health education focused on smoking, dietary changes, and the judicious application of screening technologies. The goal is to demonstrate these can work in the "real world" of the community workplace. The challenge of designing and conducting effective studies must include practical solutions to ethical as well as methodological issues.

FRAP reveals that mobility of oestrogen receptor-alpha is ligand- and proteasome-dependent

Here we report the use of fluorescence recovery after photobleaching (FRAP) to examine the intranuclear dynamics of fluorescent oestrogen receptor-alpha (ER). After bleaching, unliganded ER exhibits high mobility (recovery t1/2 < 1 s). Agonist (oestradiol; E2) or partial antagonist (4-hydroxytamoxifen) slows ER recovery (t1/2 approximately 5-6 s), whereas the pure antagonist (ICI 182,780) and, surprisingly, proteasome inhibitors each immobilize ER to the nuclear matrix. Dual FRAP experiments show that fluorescent ER and SRC-1 exhibit similar dynamics only in the presence of E2. In contrast to reports that several nuclear proteins show uniform dynamics, ER exhibits differential mobility depending upon several factors that are linked to its transcription function.

A shift in the phenotype of melan-A-specific CTL identifies melanoma patients with an active tumor-specific immune response

In a significant proportion of melanoma patients, CTL specific for the melan-A(26/7-35) epitope can be detected in peripheral blood using HLA-A2/peptide tetramers. However, the functional capacity of these CTL has been controversial, since although they prove to be effective killers after in vitro expansion, in some patients they have blunted activation responses ex vivo. We used phenotypic markers to characterize melan-A tetramer(+) cells in both normal individuals and melanoma patients, and correlated these markers with ex vivo assays of CTL function. Melanoma patients with detectable melan-A tetramer(+) cells in peripheral blood fell into two groups. Seven of thirteen patients had a CCR7(+) CD45R0(-) CD45RA(+) phenotype, the same as that found in some healthy controls, and this phenotype was associated with a lack of response to melan-A peptide ex vivo. In the remaining six patients, melan-A tetramer(+) cells were shifted toward a CCR7(-) CD45R0(+) CD45RA(-) phenotype, and responses to melan-A peptide could be readily demonstrated ex vivo. When lymph nodes infiltrated by melan-A-expressing melanoma cells were examined, a similar dichotomy emerged. These findings demonstrate that activation of melan-A-specific CTL occurs in only some patients with malignant melanoma, and that only patients with such active immune responses are capable of responding to Ag in ex vivo assays.

Molecular mechanisms of selective estrogen receptor modulator (SERM) action

In females, estrogens play a key role in reproduction and have beneficial effects on the skeletal, cardiovascular, and central nervous systems. Most estrogenic responses are mediated by estrogen receptors (ERs), either ER alpha or ER beta, which are members of the nuclear receptor superfamily of ligand-dependent transcription factors. Selective estrogen receptor modulators (SERMs) are ER ligands that in some tissues act like estrogens, but block estrogen action in others. Thus, SERMs may exhibit an agonistic or antagonistic biocharacter depending on the context in which their activity is examined. For example, the SERMs tamoxifen and raloxifene both exhibit ER antagonist activity in breast and agonist activity in bone, but only tamoxifen manifests agonist activity in the uterus. Numerous studies have examined the molecular basis for SERM selectivity. Collectively they indicate that different ER ligands induce distinct structural changes in the receptor that influence its ability to interact with other proteins (e.g., coactivators or corepressors) critical for the regulation of target gene transcription. The relative expression of coactivators and corepressors, and the nature of the ER and of its target gene promoter affect SERM biocharacter. Taken together, SERM selectivity reflects the diversity of ER forms and coregulators, cell type differences in their expression, and the diversity of ER target genes. This model provides a basis for understanding the molecular mechanisms of SERM action, and should help identify new SERMs with enhanced tissue or target gene selectivity.

Reliability and validity of DSM-IV axis V

OBJECTIVE

The authors investigated the reliability and convergent and discriminant validity of the DSM-IV Global Assessment of Functioning Scale and two experimental DSM-IV axis V global rating scales, the Global Assessment of Relational Functioning Scale and the Social and Occupational Functioning Assessment Scale.

METHOD

Forty-four patients admitted to a university-based outpatient community clinic were rated by trained clinicians on the three DSM-IV axis V scales. Patients also completed self-report measures of DSM-IV symptoms as well as measures of relational, social, and occupational functioning.

RESULTS

The Global Assessment of Functioning Scale, Global Assessment of Relational Functioning Scale, and Social and Occupational Functioning Assessment Scale all exhibited very high levels of interrater reliability. Factor analysis revealed that the Global Assessment of Relational Functioning Scale and the Social and Occupational Functioning Assessment Scale are each more related to the Global Assessment of Functioning Scale individually than they are to each other. The Global Assessment of Functioning Scale was significantly related to concurrent patient responses on the SCL-90-R global severity index. The Social and Occupational Functioning Assessment Scale was significantly related to concurrent patient responses on the SCL-90-R global severity index and to a greater degree with both the Social Adjustment Scale global score and the Inventory of Interpersonal Problems total score. Although the Global Assessment of Relational Functioning Scale was not significantly related to any of the three self-report measures, it was related to the presence of clinician-rated axis II pathology.

CONCLUSIONS

The three axis V scales can be scored reliably. The Global Assessment of Relational Functioning Scale and the Social and Occupational Functioning Assessment Scale evaluate different constructs. These findings support the validity of the Global Assessment of Functioning Scale as a scale of global psychopathology; the Social and Occupational Functioning Assessment Scale as a measure of problems in social, occupational, and interpersonal functioning; and the Global Assessment of Relational Functioning Scale as an index of personality pathology. The authors discuss further refinement and use of the three axis V measures in treatment research.

Indentation of an osteochondral repair: sensitivity to experimental variables and boundary conditions

The sensitivity of the affects of indenter radius, defect depth, cartilage permeability and flow boundary conditions, on the indentation testing of a repairing osteochondral defect was investigated. Since the boundary condition on the flow across the cartilage repair-subchondral bone interface is not known, the effects of two different conditions were investigated: free-flow and no-flow. A poroelastic finite element model of an osteochondral defect at different stages of the repair process was developed using dimensions typical of the rabbit knee. Results showed when the radius of the indenter was much less than the thickness of the cartilage the sensitivity of the indentation displacement to flow boundary conditions decreased. Simulated indentation displacement was insensitive to bone regeneration up to 50% of the initial defect depth, which suggests that only the properties of the material in the upper-half of the defect are being evaluated. Small variations in permeability had little affect on the simulated indentation. In a fully repaired defect, the simulated indentation is independent of the boundary condition. However, while the defect is in the process of repair and the regenerated cartilage is deeper than the host, indentation is sensitive to the flow boundary condition. Based on these results, and feasible experimental conditions, we conclude that the boundary condition on the repair-subchondral bone interface must be known in all cases except when the defect approaches full repair, if accurate estimates of material properties are to be obtained from indentation.

Effects of antiandrogens on chromatin remodeling and transcription of the integrated mouse mammary tumor virus promoter

Inhibition of the ligand-activated androgen receptor (AR) by antiandrogens plays an important role in the treatment of various hyperandrogenic disorders including prostate cancer. However, the molecular mechanisms of antiandrogen activity in vivo remain unclear. In this study we analyzed the effects of cyproterone acetate (CPA), flutamide (F), and hydroxyflutamide (OHF) on transcriptional activation and chromatin remodeling of the genomically integrated mouse mammary tumor virus (MMTV) promoter. This promoter has provided an excellent model system to study the impact of steroid hormones on transcriptional activation in the context of a defined chromatin structure. The MMTV hormone response element is positioned on a phased nucleosome, which becomes remodeled in response to steroids. We utilized this model system in mouse L-cell fibroblasts that contain a stably integrated MMTV promoter. In these cells, dihydrotestosterone (DHT) induced a large increase of AR protein levels that correlated with transcriptional activation and chromatin remodeling of the MMTV promoter. Coadministration of DHT and CPA or DHT and OHF in these cells inhibited the increase of AR levels, which resulted in a strong blockage of transcriptional activation and chromatin remodeling of the MMTV promoter. In contrast, F had no significant influence on these activities. We conclude that a major portion of the antiandrogenic effects of CPA and OHF in vivo are mediated by the reduction of AR levels.

Synthesis and incorporation of pyrrole carboxamide nucleoside triphosphates by DNA polymerases

We have synthesised and examined the enzymatic incorporation properties of the 5'-triphosphates of 2'-deoxyribosyl pyrrole 3-monocarboxamide (dMTP) and 2'-deoxyribosyl pyrrole 3,4-dicarboxamide (dDTP). These analogues we had hoped would behave as ambivalent base analogues in that they can present two alternative hydrogen-bonding faces either by rotation about the carboxamide group or about the glycosidic bond. The two pyrrole derivatives, dMTP and dDTP, exhibit a preference for incorporation with Klenow polymerase. They are preferentially incorporated as either A or C.

Structure and function of Cdc6/Cdc18: implications for origin recognition and checkpoint control

Cdc6/Cdc18 is a conserved and essential component of prereplication complexes. The 2.0 A crystal structure of an archaeal Cdc6 ortholog, in conjunction with a mutational analysis of the homologous Cdc18 protein from Schizosaccharomyces pombe, reveals novel aspects of Cdc6/Cdc18 function. Two domains of Cdc6 form an AAA+-type nucleotide binding fold that is observed bound to Mg.ADP. A third domain adopts a winged-helix fold similar to known DNA binding modules. Sequence comparisons show that the winged-helix domain is conserved in Orc1, and mutagenesis data demonstrate that this region of Cdc6/Cdc18 is required for function in vivo. Additional mutational analyses suggest that nucleotide binding and/or hydrolysis by Cdc6/Cdc18 is required not only for progression through S phase, but also for maintenance of checkpoint control during S phase.

Evaluation of newer treatment interventions for psychotic depression

Psychotic depression is characterized by greater severity, higher rate of recurrence, greater incapacitation, more frequent hospitalization, and longer episodes than nonpsychotic depression. The use of combined tricyclic antidepressants (TCAs) and neuroleptic therapy, as well as electroconvulsive therapy, has proven effectiveness in the treatment of psychotic depression. Although it is limited, evidence for efficacy of selective serontonin reuptake inhibitors both alone and in combination with antipsychotics in psychotic depression suggests that these strategies may provide a desirable alternative to the traditional TCA- neuroleptic therapy. These treatments, in addition to the continual introduction of new psychotropic agents suggest that the prospect of future research in this area is promising.

Characterization of transiently and constitutively expressed progesterone receptors: evidence for two functional states

Activated steroid receptors induce chromatin remodeling events in the promoters of some target genes. We previously reported that transiently expressed progesterone receptor (PR) cannot activate mouse mammary tumor virus (MMTV) promoter when it adopts the form of ordered chromatin. However, when expressed continuously, the PR acquires this ability. In this study we explored whether this gain of function occurs through alterations in nucleoprotein structure at the MMTV promoter or through changes in receptor status. We observed no major structural differences at the MMTV promoter in the presence of constitutively expressed PR and found its mechanism of activation to be very similar to that of the glucocorticoid receptor (GR). However, a systematic comparison of the functional behavior of the transiently and constitutively expressed PR elucidated significant differences. The transiently expressed PR is activated in the absence of ligand by cAMP and by components in FBS and has significantly increased sensitivity to progestins. In contrast, the constitutively expressed PR is refractory to activation by cAMP and serum and has normal sensitivity to its ligand. In addition, while the PR is localized to the nucleus in both cases, a significant fraction of the transiently expressed PR is tightly bound to the nucleus even in the absence of ligand, while the majority of constitutively expressed PR is not. These results strongly suggest that the PR undergoes processing in the cell subsequent to its initial expression and that this processing is important for various aspects of its function, including its ability to productively interact with target genes that require chromatin remodeling for activation.

In vitro evaluation of the effect of dimethyl sulfoxide on equine articular cartilage matrix metabolism

OBJECTIVE

To evaluate the effects of dimethyl sulfoxide (DMSO) on equine articular cartilage matrix metabolism.

STUDY DESIGN

Using a cartilage explant culture system, proteoglycan (PG) synthesis, PG release, lactate metabolism, chondrocyte viability, and metabolism recovery were determined after cartilage exposure to DMSO.

SAMPLE POPULATION

Cartilage harvested from metacarpophalangeal and metatarsophalangeal joints of 12 horses (age range, 1 to 10 years).

METHODS

Explants were exposed to concentrations of DMSO (1% to 20%) for variable times (3 to 72 hours). PG synthesis and release were determined by a radiolabel incorporation assay and dimethylmethylene blue (DMMB) dye assay, respectively. Lactate released into culture media was measured, and chondrocyte viability was assessed using the Formizan Conversion Assay and a paravital staining protocol. Metabolism recovery was assessed in explants that were allowed to recover in maintenance media after exposure to DMSO.

RESULTS

PG synthesis and lactate metabolism were inhibited in a dose- and time-dependent manner after exposure to DMSO concentrations > or = 5%; there was no significant alteration in PG release. No change in chondrocyte viability was detected after incubation with DMSO. PG synthesis and lactate metabolism returned to baseline rates when allowed a recovery period after exposure to DMSO.

CONCLUSIONS

DMSO concentrations > or = 5% suppress equine articular cartilage matrix metabolism. Suppression of PG synthesis and lactate metabolism is reversible and does not appear to be the result of chondrocyte death.

CLINICAL RELEVANCE

Equine clinicians adding DMSO to intraarticular lavage solutions should be aware that DMSO may have deleterious effects on equine articular cartilage matrix metabolism.