Abstract 1815: AVA6000, a novel Precision medicine, targeted to the tumor microenvironment via Fibroblast Activation Protein (FAP) mediated cleavage

AVA6000 is a therapeutic product based on proprietary pre|CISION™ technology which incorporates a substrate that is sensitive to cleavage by FAP. The pre|CISION™ substrate can be utilized in a drug conjugate linker or to generate chemotherapy prodrugs that are only activated in the tumor microenvironment. AVA6000 consists of a doxorubicin molecule covalently bonded to a dipeptide (pyridine-4-carbonyl)-D-Ala-L-Pro), which is designed to be susceptible to hydrolysis by Fibroblast Activation Protein α (FAP) but is resistant to hydrolysis by both closely related and wider mammalian peptidases. FAP, a post-prolyl endopeptidase, is overexpressed on the surface of activated fibroblastic cells which are abundant in the supporting stroma of over 90% of malignant epithelial cancers, as well as in bone and soft tissue sarcoma. While FAP is also present both in normal tissues and as a soluble enzyme in plasma, levels are significantly lower than those present in malignant epithelial cancers. Consequently, AVA6000 has the potential to deliver doxorubicin directly to the tumor microenvironment, while exposing the patient to a lesser degree of doxorubicin-associated toxicities. The primary mechanism of action of doxorubicin is thought to involve stabilisation of a topoisomerase-II-DNA cleavable complex through non-specific DNA-intercalation. The non-specific DNA-intercalation causes a number of downstream effects, which may ultimately result in apoptotic cell death. Although doxorubicin has been one of the most effective and widely used chemotherapeutic agents for the treatment of various solid malignancies for over 40 years, its clinical utility is limited by dose-limiting toxicities, including myelosuppression and cardiotoxicity. The unique FAP specificity of the N-(pyridine-4-carbonyl)-D-Ala-L-Pro leaving group conjugated to doxorubicin in AVA6000 is supported by the absence of cleavage of the fluorogenic analogue, 3114-AMC, in FAP gene-knockout mice (Fap-/-). In vitro cytotoxicity assessments involving human tumor cell lines showed that AVA6000 was between 80-fold to 4,000-fold less cytotoxic compared to doxorubicin. In several in vivo efficacy studies in tumours with high FAP levels, AVA6000 significantly decreased tumor volume and increased survival in a dose-dependent manner. In a PDX model of osteosarcoma, AVA6000 significantly decreased tumor volume while doxorubicin had no significant effect. The efficacy and tolerability profile of AVA6000 strongly support its clinical development, and a Phase I trial in patients with locally advanced or metastatic selected solid tumours in underway.

Citation Format: Fiona McLaughlin, Sarah E. Poplawski, David G. Sanford, Andrew Saunders, Jack H. Lai, Matthew Vincent, William W. Bachovchin, Neil Bell. AVA6000, a novel Precision medicine, targeted to the tumor microenvironment via Fibroblast Activation Protein (FAP) mediated cleavage [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1815.

A Novel In Vitro Model for Determining the Optimum pH and Dose Volume of New Liquid Alginate for Infant Reflux Suppression

BACKGROUND

Gastroesophageal reflux frequently occurs in infants from birth to 2 years and is characterised by reflux and regurgitation often occurring during or immediately after feeds. These reflux events can range in both frequency and severity, and as the reflux events increase, they become increasingly distressing for both the infant and the parent. The study aimed to characterise the properties of a new infant liquid alginate product, determining the optimum gastric pH and dose volume for maximum reflux suppressant activity.

METHODS

An in vitro infant stomach model was designed and developed that allowed products to be assessed for their reflux suppression activity. The validation of the model was completed by three independent operators comparing a milk control with infant Gaviscon to evaluate the models' robustness, reproducibility, and ease of use. The model was used to establish reflux suppression activity of a new liquid alginate infant formulation in comparison with a milk control. Suppression activity was assessed at varying doses and pH within a physiological range.

RESULTS

The validation study demonstrated no significant difference in refluxate volumes for the milk control within each reflux event when comparing across the three individual operators. Similarly, no statistical differences were seen during the infant Gaviscon experiments, confirming the robustness and reproducibility of the model. Significant reflux suppression was seen across the pH range (except at pH 5.75); the pH most advantageous for reflux suppression was pH 5.25. The optimum dose volume for consistently suppressing reflux was shown to be 5 ml. An infant stomach model was designed for evaluating reflux suppression activity of a formulation of liquid alginate. The optimum gastric pH and dose volume for demonstrating significant reflux suppression and the thickening of formula milk by the infant liquid alginate formulation were established.

CONCLUSION

This study confirms the mode of action of the alginate formula, demonstrating a superior reduction in the retrograde movement of in vitro gastric contents and volume of regurgitation. The study also demonstrates that optimal performance occurs in conditions that are in line physiologically with the target patient. Both actions compliment and support the efficacy of the alginate formulation as a reflux therapy agent.

The novel toluidine sulphonamide EL102 shows pre-clinical in vitro and in vivo activity against prostate cancer and circumvents MDR1 resistance

Background:

Taxanes are routinely used for the treatment of prostate cancer, however the majority of patients eventually develop resistance. We investigated the potential efficacy of EL102, a novel toluidine sulphonamide, in pre-clinical models of prostate cancer.

Methods:

The effect of EL102 and/or docetaxel on PC-3, DU145, 22Rv1 and CWR22 prostate cancer cells was assessed using cell viability, cell cycle analysis and PARP cleavage assays. Tubulin polymerisation and immunofluorescence assays were used to assess tubulin dynamics. CWR22 xenograft murine model was used to assess effects on tumour proliferation. Multidrug-resistant lung cancer DLKPA was used to assess EL102 in a MDR1-mediated drug resistance background.

Results:

EL102 has in vitro activity against prostate cancer, characterised by accumulation in G2/M, induction of apoptosis, inhibition of Hif1α, and inhibition of tubulin polymerisation and decreased microtubule stability. In vivo, a combination of EL102 and docetaxel exhibits superior tumour inhibition. The DLKP cell line and multidrug-resistant DLKPA variant (which exhibits 205 to 691-fold greater resistance to docetaxel, paclitaxel, vincristine and doxorubicin) are equally sensitive to EL102.

Conclusion:

EL102 shows potential as both a single agent and within combination regimens for the treatment of prostate cancer, particularly in the chemoresistance setting.

Abstract B18: EL102: A novel dual inhibitor which demonstrates additive prostate cancer inhibitory activity in combination with docetaxel in vitro and in mouse models

Introduction: EL102, a novel toluidine sulphonamide, was developed from a phenotypic screen to develop novel small molecule inhibitors of the hypoxia signalling cascade. It is a dual-inhibitor of apoptosis and angiogenesis, and exerts its action though the inhibition of Hif1 alpha induced hypoxic signalling pathways and induction of the Caspase 3/7 apoptotic cascade. The drug has equal activity against normoxic and hypoxic tumour cells indicating that it may be equally active in these different tumour compartments.

Hypothesis: We hypothesize that the dual inhibition of anti-apoptotic and angiogenic pathway is a viable therapeutic strategy for the treatment of prostate cancer, and may be additive to taxane-based chemotherapeutic strategies.

Experimental Procedures: We assessed the ability of EL102 to inhibit prostate cancer cell proliferation and cell motility in vitro in normal prostate RWPE1, androgen dependent CRW22 and its androgen independent variant 22Rv2,and the metastatic prostate cancer cell lines PC3 and DU145. Mechanistic studies included the effects of EL102 on VEGF, IL-6 and Il-8 secretion and ability to inhibit Hif1a expression. Additionally we assessed the activity of EL102 in combination with docetaxel in vitro and in murine models using CRW22 xenografts.

Results: Prostate cancer cell lines are sensitive to EL102 with IC50s for inhibition of cell proliferation in the region of 10-50nM. Of particular interest was the comparable sensitivity of the androgen independent 22Rv1 cell line and it androgen dependent parent cell line CRW22, suggesting that EL102 may also be active in hormone refractory prostate cancer. Additionally we demonstrate dose response for the inhibition of cell motility in the metastatic prostate cancer cell lines DU145. In CRW22 murine mouse models treatment with EL102 resulted in significantly decreased tumour volume compared to control. A docetaxel and EL102 combination arm demonstrated the greater inhibition of tumour growth than EL102 or docetaxel alone.

Conclusions: EL102 is a potential therapeutic agent for the treatment of prostate cancer, as a single agent or in combination with docetaxel. The histopathology of tumours from mice treated with EL102 in combination with docetaxel on Ki-67, Hif1 alpha, VEGF and apoptosis in vivo is evaluated. Future studies will establish the efficacy of EL102 in a PC3 metastatic prostate cancer mouse model. Additionally the ability of EL102 to circumvent the classic drug resistance mechanisms MDR1, MRP1 and BCRP, and overcome taxane resistance will be presented.

Citation Format: Aidan Toner, Fiona McLaughlin, Jill McMahon, Francis J. Giles, Frank Sullivan, Laura Breen, Martin Clynes, Joe D. Lewis, Sharon A. Glynn. EL102: A novel dual inhibitor which demonstrates additive prostate cancer inhibitory activity in combination with docetaxel in vitro and in mouse models [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr B18.

Detecting and coping with disruptive shocks in Arctic marine systems: a resilience approach to place and people

It seems inevitable that the ongoing and rapid changes in the physical environment of the marine Arctic will push components of the region's existing social-ecological systems-small and large-beyond tipping points and into new regimes. Ongoing changes include warming, freshening, acidification, and alterations to food web structure. In anticipation we pose three distinct but interrelated challenges: (1) to explore existing connectivities within components of the marine system; (2) to seek indicators (if they exist) of approaching regime change through observation and modeling; and (3) to build functional resilience into existing systems through adaptation-oriented policy and to have in hand transformative options when tipping points are crossed and new development trajectories are required. Each of the above challenges is scale dependent, and each requires a much deeper understanding than we currently have of connectivity within existing systems and their response to external forcing. Here, we argue from a global perspective the need to understand the Arctic's role in an increasingly nonlinear world; then describe emerging evidence from new observations on the connectivity of processes and system components from the Canada Basin and subarctic seas surrounding northern North America; and finally posit an approach founded in "resilience thinking" to allow northern residents living in small coastal communities to participate in the observation, adaption and-if necessary-transformation of the social-ecological system with which they live.

Abstract LB-385: Pre-clinical development of the novel, broad spectrum, anti-cancer agent EL102

Introduction

EL102 was identified using a systems biology approach to develop novel small molecule antagonists of the hypoxia signalling cascade. EL102 inhibits HIF1alpha signalling in cells with and IC50 of approximately 13 nM. In addition to the potent inhibition of HIF1alpha signalling, EL102 causes a reduction in cellular proliferation across a broad range of solid and liquid tumor cells with IC50 values in the low nM range. At these concentrations, EL102 induces caspase 3/7 and drives cells into apoptosis. Further characterisation of EL102 was undertaken in human xenografts as a single agent, where significant tumor growth reduction (TGI 69%) was observed at concentrations that did not produce significant body weight loss. Due to its favourable pharmacokinetic and physiochemical properties, EL102 was subsequently selected as a clinical development candidate and entered formal pre-clinical development studies in late 2010. The anticipated date of Phase I entry is 2H 2011.

Objectives

The objectives of this study were to define the mechanism of action of the clinical development candidate EL102 and to identify the best dose and schedule of the drug for the Phase I study based upon efficacy and toxicity

Methodology

EL102 was profiled as both a single agent and in combination with standard of care in xenograft models where efficacy had been demonstrated in vitro. EL102 was administered either daily bid for 28 days, or in cycles of either 3 days or 7 days with a dosing holiday. Tumor volumes and, in some cases, tumor PK were assessed as primary readouts.

An oral formulation of EL102 was developed for clinical usage, and administered bid in both a 14 day dose range finder and subsequently a 28 day cycle to rats and dogs. TK samples were obtained and analysed for both species.

Preliminary data

EL102 demonstrates encouraging anti-tumor efficacy in a number of cell lines in vitro, with low nM IC50 values obtained in both solid and liquid tumor types. Subsequent profiling of EL102 in multiple myeloma patient cells, led to cell kill in primary tumor cells with no effect on the tumor microenvironment, suggesting that multiple myeloma cells may be particularly sensitive to the drug. In addition, mechanism of action studies demonstrates that EL102 is a potent antagonist of several nuclear receptors, (including PR, AR and ERRalpha) and the ADORA3 GPCR. This data, together with the inhibition of HIF1alpha signalling, positions EL102 as a novel anti-cancer agent with activity in tumors which have deregulated key signalling pathways and provides a strategy for subsequent patient stratification in the clinic. Toxicology data in rodents suggests that EL102 is well tolerated at exposure levels which produce an anti-tumor effect in mouse models and support the further clinical development of EL102 in cancer patients in a wide range of other tumor types including multiple myeloma.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-385. doi:10.1158/1538-7445.AM2011-LB-385

Abstract 3647: Gene expression analysis in AML cell line MV4-11 following treatment with the anti-cancer aptamer AS1411

AS1411 is a 26-base DNA aptamer which is shortly due to enter a phase IIb clinical trial in acute myeloid leukaemia (AML). In an initial phase II trial in AML, combination of AS1411 with cytarabine produced an increased response rate compared to cytarabine alone, and AS1411 was well tolerated. When cells in culture are exposed to AS1411, a cytostatic effect is observed initially, followed by cell death after 72 to 96 hours. Several mechanisms have been described by which AS1411 exerts these effects; we performed a gene expression microarray analysis to evaluate which cellular pathways and functions were modulated by AS1411 treatment. We also sought to identify biomarkers for drug activity which could be translated to use in the clinic in the forthcoming phase IIb trial.

The AML cell line MV4-11 was exposed to AS1411 at two concentrations; these approximated concentrations observed in patient plasma following two different doses of AS1411 in the prior phase II trial. mRNA was isolated from cells at 24 and 72 hours, time points associated with cytostatic and cytotoxic effects, respectively. Controls at time zero and in the absence of drug were also analysed. The Affymetrix plus 2™ arrays were processed and the raw data were normalised according to the Rosetta Resolver model. The gene lists for each time point (4 replicates) were then clustered non-hierarchically and distributed into pathways using MetaCore™.

Gene clusters were separately generated to identify specific genes which were up- or down-regulated at different doses and different time-points. These were then compared to identify those that were regulated by a common pathway. Pathways and regulatory networks that were either up- or down-regulated after exposure to AS1411 included nuclear import/export, nucleotide biosynthesis/metabolism, DNA damage response and pathways related to cell cycle control and cell death (including genes in the p53 signalling pathway). While some of these activities had been shown previously to be modified upon AS1411 exposure, other findings are novel.

A number of genes showed marked changes in expression following AS1411 exposure; these are undergoing validation by quantitative PCR as potential biomarkers. They include upregulated genes TP53i3 and p21 (p53 signalling pathway), RDM1 (DNA damage), YPEL3 and DAPK1 (proliferation and apoptosis) as well as individual genes such as GNG7. Several genes, including INO80C, exhibited a marked dose-dependent down regulation.

This work demonstrates that a number of cellular activities are modulated by AS1411, and provides important information for the future clinical development of AS1411, including pointers to the selection of biomarkers for analysis of blood and bone marrow samples from patients in the forthcoming phase IIb study in AML.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3647.

Abstract 4455: Differential response to AS1411 in a pair of VHL-positive and VHL-negative renal carcinoma cell lines

AS1411 is a G-rich phosphodiester oligonucleotide that forms a stable G-quadruplex structure and functions as an aptamer to nucleolin. Preclinical studies have shown that AS1411 exhibits antiproliferative activity against a variety of cancer types, but has little effect on normal cells. In a Phase I clinical trial of AS1411 in 30 patients with advanced solid tumors, there were no serious adverse events associated with AS1411 treatment. Furthermore, there was evidence of clinical benefit, particularly in patients with metastatic renal cell carcinoma (RCC), including durable disease stabilization and objective responses. A phase II trial of AS1411 in metastatic RCC is now underway.

Renal cell carcinomas (RCC) are the most common form of kidney cancer and the majority of these (75%) have biallelic inactivation of the von Hippel-Lindau tumor suppressor gene (VHL) by mutation or less commonly by hypermethylation. The VHL gene product, pVHL, has multiple functions including ubiquitination of HIF transcription factors, regulation of endocytosis, and control of microtubule orientation. Here we investigated the effect of AS1411 on two previously established matched RCC cell lines with and without functional VHL: RCC4 cells which harbor a mutation in VHL and do not express functional VHL (VHL-negative), and RCC4/VHL which are stably transfected to express wild type VHL (VHL-positive). Using a variety of techniques (MTT assay, colony forming assay, and cell cycle analysis), we observed a clear difference in response to AS1411 between RCC4 and RCC4/VHL cells, with the VHL-negative line being much more sensitive to growth inhibition following AS1411 treatment. Cell cycle analysis showed that VHL-negative RCC4 cells treated with AS1411 accumulate predominantly in S phase after 72 h (as seen in other AS1411-responsive cell lines), followed by S and G2/M phase of cell cycle after 96 h treatment. In contrast, there was no perturbation of the cell cycle in the VHL-positive RCC4/VHL cells. Further studies are ongoing to determine if this is a general effect, dependent directly on pVHL, or if it is related to specific phenotypic differences between these two cell lines. In any case, the availability of two closely related cell lines with markedly different sensitivities to AS1411 should greatly facilitate our efforts to identify markers that may predict response to AS1411.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4455.

Abstract 3642: AS1411 causes a specific increase in levels of cell surface nucleolin in responsive cell lines

AS1411 is a 26-mer guanine-rich oligodeoxynucleotide that has antiproliferative activity against many types of cancer cells, but not against normal cells. It is currently being tested as an anticancer agent in Phase II clinical trials. Previously, we reported that this agent has a novel mechanism of action that involves formation of a stable G-quadruplex structure that can bind as an aptamer to nucleolin, a multifunctional protein expressed at high levels by cancer cells. Nucleolin is a predominantly nuclear protein, but can also be present in the cytoplasm and on the surface of cells, where it has been reported to mediate the endocytosis of several ligands. Cell surface nucleolin is believed to play an important role in AS1411 activity, although the precise details have yet to be elucidated. In the present study, we have evaluated the levels of cell surface nucleolin in human cell lines that are responsive or resistant to AS1411, before and after treatment with AS1411. Levels were examined by flow cytometry, with gating to exclude non-viable permeable (PI-positive) cells, and by western blotting of cell surface proteins, isolated using a cell-impermeable biotinylating agent. The amount of cell surface nucleolin appeared to be similar in untreated cells that were either sensitive to AS1411 (DU145 prostate cancer cells and MV-4-11 leukemia cells) or resistant to AS1411 (Hs27 non-malignant skin fibroblasts). However, in the sensitive cell lines, we observed a dramatic and time-dependent increase in levels of cell surface nucleolin in response to AS1411 treatment, whereas there was no significant change in the resistant Hs27 cells. We determined that this AS1411-induced increase in cell surface nucleolin in the cancer cells was not simply a reflection of apoptosis because it was not observed when apoptosis was induced by UV irradiation. We did not observe any changes in the levels of nucleolin in nuclear, cytoplasmic, or membrane extracts, or in total cell lysates, following treatment with AS1411, suggesting a specific re-localization of nucleolin rather than an increase in overall levels. These new results do not support our previous hypothesis that baseline levels of cell surface nucleolin determine responsiveness to AS1411. However, they do clearly demonstrate that “externalization” of nucleolin is a specific response to AS1411 and thereby confirm the important role of cell surface nucleolin in the mechanism of action of AS1411.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3642.

Abstract 2614: Anti-tumor efficacy and pharmacokinetics of the novel aptamer AS1411 in a continuous infusion nude rat xenograft model

AS1411 is a novel DNA aptamer that binds to the multi-functional protein nucleolin and induces cell death. AS1411 has shown activity at two different doses in combination with cytarabine in a phase II study of patients with AML.

We have previously shown that AS1411 has activity against a range of solid and hematological cancer cell lines, with IC50 values between 1 and 10 μM, when cells are exposed to AS1411 continuously for more than 3 days. We have also demonstrated efficacy in vivo in both lung (A549) and renal (A498) mouse xenografts. However, it has been challenging to provide optimal continuous dosing of AS1411 in mice; use of osmotic pumps or intraperitoneal bolus injection have been associated with low drug exposure. In the current study, we optimized the continuous infusion model by using nude, athymic rats with a surgically implanted catheter in a two-cycle xenograft study. Plasma and tumor samples were collected for PK determination, allowing a correlation of PK with efficacy.

The colorectal cell line HT29, which is sensitive to AS1411 in vitro, was used in this study. Cells (5×106) were implanted subcutaneously in the flank of female nude rats and tumors were allowed to grow to approximately 200 − 300 mm3 before surgical cannulation of the femoral vein. Following recovery, animals received AS1411 at 40, 80 or 180 mg/kg/day for two 7 day cycles of continuous infusion, 7 days apart. A vehicle control group received saline.

Animals in the 80 and 180 mg/kg/day groups exhibited a significant (p<0.01) reduction in tumor volume compared to control animals at day 33 and at day 22 (interim analysis); this was not observed for animals in the 40mg/kg/day group (40mg kg/day in this model does not directly correlate to the clinical dose of the same name). AS1411 was well-tolerated by all animals in all dose groups.

Plasma levels of AS1411 were measured at the three dose levels after one cycle of treatment. Mean AS1411 plasma concentrations were 0.7, 2.5 and 5.0 μM, for rats treated at 40, 80 and 180 mg/kg/day, respectively. The plasma concentrations in the two higher dose groups are within the range of the in vitro IC50 concentrations of a panel of cell lines.

We conclude that AS1411 shows activity in vivo in the HT29 nude rat xenograft model. Doses associated with significant reductions in tumor volume were those that produced plasma concentrations close to the IC50 level for AS1411. This correlation has been used in planning further clinical development of AS1411, including a phase IIb study of patients with AML.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2614.

Histone deacetylase inhibitors open new doors in cancer therapy

Cancer drug development has moved from conventional cytotoxic chemotherapeutics to a more mechanism-based targeted approach towards the common goal of tumour growth arrest. The rapid progress in chromatin research has supplied a plethora of potential targets for intervention in cancer. Here, we focus on the histone deacetylase (HDAC) inhibitors, together with their current status of clinical development and potential utility in cancer therapy. HDACs have been widely implicated in growth and transcriptional control, and inhibition of HDAC activity using small molecules causes apoptosis in tumour cells. We discuss the rationale for the development of HDAC inhibitors as novel anti-cancer agents, the potential clinical application and explore ideas on how we may move towards patient stratification with the possibility of increasing efficacy in the clinic.

Histone deacetylase inhibitors in psoriasis therapy

Psoriasis is recognised as a multifactorial disease with inflammatory, proliferative, angiogenic and genetic components contributing to the pathology. The disease, which may vary in intensity, remains clinically unmet although there have been several recent advances that have had a substantial impact on suffering. Histone deacetylase inhibitors represent a new class of therapeutic agent, initially developed for oncology, which prevent cell proliferation and induce differentiation. Here we discuss the possible application of HDAC inhibitors to psoriasis, focussing particularly on their anti-proliferative and anti-inflammatory activity. Our view, based upon the emerging clinical properties of HDAC inhibitors, reflects the growing recognition that HDAC inhibitors will be important therapeutic agents in diseases other than cancer.

The cell cycle, chromatin and cancer: mechanism-based therapeutics come of age

Tumour cells grow and divide in an uncontrolled fashion. Recent advances in the cell cycle have uncovered new mechanisms that integrate growth and division with chromatin and gene expression control. Small-molecule drugs that target key enzyme classes involved in these pathways, the cyclin-dependent kinases (Cdk) in the cell cycle and histone deacetylases (HDAC) in chromatin control, have entered clinical studies, with emerging clinical efficacy. These new mechanism-based approaches could provide significant improvements over many current chemotherapeutics.

Glucocorticoid-induced osteopenia in the mouse as assessed by histomorphometry, microcomputed tomography, and biochemical markers

Glucocorticoids are potent anti-inflammatory molecules used in the treatment of asthma, rheumatoid arthritis, inflammatory bowel disease, and other inflammatory and dermatological diseases, as well as in posttransplantation immunotherapy. Although glucocorticoids have been prescribed for many years, their potential side effects, when administered orally, can prevent their long-term use. The most serious side effect observed in the clinic is glucocorticoid-induced osteoporosis (GIOP). To develop a small animal model to characterize glucocorticoid-induced bone loss, we carried out a series of experiments using BALB/c mice given daily intraperitoneal doses of the synthetic glucocorticoid, dexamethasone. Following dexamethasone treatment, the mice became osteopenic, with highly significant decreases in bone formation rate and mineral apposition rate, as assessed by standard histomorphometry. Moreover, 3 week treatment with dexamethasone resulted in a decrease in trabecular thickness and trabecular number with an increase in surface-to-volume ratio of trabeculae in the distal femur, as measured using microcomputed tomography (micro-CT). The serum bone formation marker, osteocalcin, was dose-dependently decreased in all mice treated with dexamethasone and showed a parallel extent of regulation to the bone formation rate changes. In addition, serum levels of leptin, recently identified as playing a role in the regulation of bone mass, increased following dexamethasone treatment. BALB/c mice therefore represent a useful model system in which the detrimental effects of glucocorticoids on bone can be studied.

Combined genomic and antisense analysis reveals that the transcription factor Erg is implicated in endothelial cell differentiation

It has recently been shown that the transcription factor Erg, an Ets family member, drives constitutive expression of the intercellular adhesion molecule 2 (ICAM-2) in human umbilical vein endothelial cells (HUVECs) and that its expression is down-regulated by the pleiotropic cytokine tumor necrosis factor alpha (TNF-alpha). To identify other Erg target genes and to define its function in the endothelium, a combined approach of antisense oligonucleotides (GeneBloc) and differential gene expression was used. Treatment of HUVECs with Erg-specific GeneBloc for 24, 48, and 72 hours suppressed Erg mRNA and protein levels at all time points. Total RNA extracted from HUVECs treated with Erg-specific or control GeneBloc was analyzed for differences in gene expression using high-density, sequence-verified cDNA arrays containing 482 relevant genes. Inhibition of Erg expression resulted in decreased expression of ICAM-2, as predicted. Four more genes decreased in Erg-deficient HUVECs were the extracellular matrix proteins SPARC and thrombospondin, the adhesive glycoprotein von Willebrand factor, and the small GTPase RhoA. Each of these molecules has been directly or indirectly linked to angiogenesis because of its role in vascular remodeling, adhesion, or shape change. Therefore, the role of Erg in vascular remodeling was tested in an in vitro model, and the results showed that HUVECs treated with Erg GeneBloc had a decreased ability to form tubulelike structures when grown on Matrigel. These results suggest that Erg may be a mediator of the TNF-alpha effects on angiogenesis in vivo.

Characterisation of the tumour necrosis factor (TNF)-(alpha) response elements in the human ICAM-2 promoter

ICAM-2 is a cell surface adhesion molecule constitutively expressed on the endothelium, involved in leukocyte recruitment into tissues. We recently showed that pro-inflammatory cytokines tumour necrosis factor (TNF)-(alpha) and interleukin (IL)-1(beta) down-regulate ICAM-2 expression at the transcriptional level. Here we investigate the elements in the ICAM-2 promoter required for the TNF-(alpha)-mediated down-regulation. Site directed mutagenesis of the ICAM-2 promoter implicated three consensus sites for Ets transcription factors in basal activity; two of these sites were also involved in the TNF-(alpha)-induced down-regulation. Electrophoretic mobility shift assays (EMSA) performed in human umbilical vein endothelial cells (HUVEC) showed that all three Ets binding sites (EBS) bind nuclear proteins. TNF-(alpha) treatment (10 ng/ml for 24 hours) decreased binding to the double -135/-127EBS, but not to the -44EBS. The Ets family member Erg was found to be constitutively expressed in HUVEC, and TNF-(alpha) down-regulated Erg protein levels. Furthermore, an Erg cDNA transactivated the ICAM-2 promoter when transiently transfected into both HeLa cells and HUVEC. Protein expression of ICAM-2 and Erg was found to be similarly regulated by TNF-(alpha) in an ex vivo artery model. These data suggest that constitutive endothelial genes ICAM-2 and Erg are on the same pathway of cytokine-dependent regulation of gene expression.

Tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta down-regulate intercellular adhesion molecule (ICAM)-2 expression on the endothelium

Leukocyte recruitment is a crucial step in inflammation. Inflammatory stimuli upregulate the expression of some endothelial adhesion molecules, such as E-selectin or ICAM-1, but not of others such as ICAM-2. ICAM-2, a constitutively expressed endothelial ligand for beta2 integrins LFA-1 and Mac-1, is involved in leukocyte adhesion to resting endothelium and in transmigration in vitro, however its role in inflammation is unclear. We have studied the effect of TNF-alpha and IL-1beta on ICAM-2 expression on human umbilical vein endothelial cells (HUVECs). Prolonged treatment (24 h) of HUVECs with TNF-alpha (10 ng/ml) or IL-1beta (34 ng/ml) reduced ICAM-2 surface expression to 50% of control, while interferon (IFN)-gamma had no effect. The loss in ICAM-2 surface expression correlated with a reduction of ICAM-2 mRNA to approximately 40% of control after 24 h of cytokine treatment. The activity of an ICAM-2 promoter reporter plasmid transfected into HUVECs was down-regulated by TNF-alpha and IL-1beta to similar values. Thus inflammatory cytokines inhibit ICAM-2 transcription, despite the absence of known cytokine-responsive elements in the promoter. Immunocytochemistry on HUVEC monolayers showed that ICAM-2 expression, mainly at the cell junctions in resting cells, was markedly decreased by cytokine treatment. This data suggest that ICAM-2 expression on the endothelium may be regulated during inflammation.

Chromatin structure and transcriptional regulation of the stem cell leukaemia (SCL) gene in mast cells

The stem cell leukaemia (SCL) gene is a member of the basic helix-loop-helix family of transcription factors and is essential for the development of all haematopoietic lineages. SCL is expressed in pluripotent haematopoietic stem cells and also following commitment to the erythroid, mast and megakaryocytic lineages. The mechanisms responsible for this pattern of expression are poorly understood, but are likely to illuminate the molecular basis for stem cell development and lineage commitment. Here we present the first description of the regulation of the SCL gene in mast cells. In this study we systematically analysed the chromatin structure of a 45 kb region of the murine SCL locus in mast cells. The pattern of DNase 1 and restriction endonuclease hypersensitive sites in mast cells was distinct from, but overlapped with, the pattern previously described in erythroid and primitive myeloid cells. Each potential regulatory element was tested using transient reporter assays to assess their functional significance in mast cells. These studies identified two potent enhancers, one of which was downstream of the SCL gene. Further characterisation of this 3' enhancer demonstrated that it required the presence of two distinct DNase 1 hypersensitive sites for full activity, and that it was capable of stimulating transcription from both promoter 1a and 1b. Since the 3' enhancer is active in both erythroid and mast cells, it will now be important to see whether it is independently activated in these lineages, or whether it is also active in haematopoietic stem cells.

Transcription of the SCL gene in erythroid and CD34 positive primitive myeloid cells is controlled by a complex network of lineage-restricted chromatin-dependent and chromatin-independent regulatory elements

The SCL gene (also known as TAL-1) encodes a basic helix-loop-helix transcription factor that is essential for the development of all haematopoietic lineages, and ectopic expression of which results in T cell leukaemia. SCL is expressed in normal pluripotent haematopoietic stem cells and its expression is maintained during differentiation along erythroid, mast and megakaryocytic lineages, but is extinguished following commitment to other cell types. The mechanisms responsible for this pattern of expression are poorly understood, but are likely to illuminate the molecular basis for stem cell development and lineage commitment. We have identified multiple lineage-restricted DNase I hypersensitive sites in a 45 kb region spanning the murine SCL locus. Committed erythroid cells and CD34 positive primitive myeloid cells exhibited both shared and unique DNase I hypersensitive sites whereas none were found in T cells. The function of each hypersensitive site was studied using both transient and stable reporter assays in erythroid, primitive myeloid and T cells. Multiple positive and negative regulatory elements were characterised and found to display lineage-specificity, promoter-specificity and/or chromatin-dependence. These results represent the first description of key components of a complex network of regulatory elements controlling SCL expression during haematopoiesis.

Distinct mechanisms direct SCL/tal-1 expression in erythroid cells and CD34 positive primitive myeloid cells

The SCL/tal-1 gene (hereafter designated SCL) encodes a basic helix-loop-helix transcription factor which is pivotal for the normal development of all hematopoietic lineages and which is expressed in committed erythroid, mast, and megakaryocytic cells as well as in hematopoietic stem cells. The molecular basis for expression of SCL in stem cells and its subsequent modulation during lineage commitment is of fundamental importance for understanding how early "decisions" are made during hematopoiesis. We now compare the activity of SCL promoters 1a and 1b in erythroid cells and in CD34 positive primitive myeloid cells. SCL mRNA expression in CD34 positive myeloid cells did not require GATA-1. Promoter 1a activity was weak or absent in CD34 positive myeloid cells and appeared to correlate with the presence or absence of low levels of GATA-1. However, promoter 1b, which was silent in committed erythroid cells, was strongly active in transient assays using CD34 positive myeloid cells, and functioned in a GATA-independent manner. Interestingly, RNase protection assays demonstrated that endogenous promoter 1b was active in both erythroid and CD34 positive myeloid cells. These results demonstrate that fundamentally different mechanisms regulate the SCL promoter region in committed erythroid cells and in CD34 positive myeloid cells. Moreover these observations suggest that in erythroid, but not in CD34 positive myeloid cells, promoter 1b required integration in chromatin and/or additional sequences for its activity. Stable transfection experiments showed that both core promoters were silent following integration in erythroid or CD34 positive myeloid cells. Our data therefore indicate that additional regulatory elements were necessary for both SCL promoters to overcome chromatin-mediated repression.

Lineage-restricted regulation of the murine SCL/TAL-1 promoter

The SCL/TAL-1 gene encodes a basic helix-loop-helix transcription factor that is expressed in multipotent hematopoietic progenitors before lineage commitment. Its expression is maintained during differentiation along erythroid, mast, and megakaryocytic lineages, but is repressed after commitment to nonexpressing lineages. To begin to address the molecular mechanisms underlying this complex pattern of expression, we have studied the regulation of the murine SCL promoter in erythroid and T-cell lines. Analysis of the methylation and chromatin structure of the SCL promoter region showed that SCL mRNA expression correlated with DNase hypersensitive sites and methylation status of the promoter. Transient reporter assays showed that promoter 1a was active in erythroid cells but not in T cells. Sequences between -187 and +26 were sufficient for lineage-restricted activity of promoter 1a. A joint promoter construct containing both promoter 1a and promoter 1b also exhibited lineage-restricted activity. Conserved GATA (-37), MAZ (+242), and ETS (+264) motifs were all shown to contribute to SCL promoter activity in erythroid cells, but several other motifs were not required for full promoter activity. The pattern of complexes binding to the +242 MAZ and +264 ETS sites were the same in erythroid and T cells. However, GATA-1 bound the -37 GATA site in erythroid cells, whereas in T cells GATA-3 was only able to bind weakly, if at all. Moreover, GATA-1 but not GATA-2 or GATA-3 was able to transactivate SCL promoter 1a in a T-cell environment. These results suggest that inactivity of SCL promoter 1a in T cells reflected the absence of GATA-1 rather than the presence of trans-dominant negative regulators.

Transcription factors and the regulation of haemopoiesis: lessons from GATA and SCL proteins

One of the central issues of developmental biology concerns the molecular mechanisms whereby a multipotent cell gives rise to distinct differentiated progeny. Differences between specialised cell types reflect variations in their patterns of gene expression. The regulation of transcription initiation is an important control point for gene expression and it is, therefore, not surprising that transcription factors play a pivotal role in mammalian development and differentiation. Haemopoiesis offers a uniquely tractable system for the study of lineage commitment and differentiation. The importance of transcription factors in the normal regulation of haemopoiesis is underlined by the frequency with which transcription factors are targeted by leukaemogenic mutations. Studies of the function and regulation of haemopoietic transcription factors, especially those expressed in lineage-restricted patterns, should greatly increase our understanding of the molecular control of haemopoiesis. In this review we have focused on insights provided by recent studies of the GATA and SCL proteins.

Preventing low birth weight: marketing and volunteer outreach

Low birth weight (LBW) contributes to infant mortality and continues to be a public health concern in the United States. A community-based prenatal program was established to prevent low birth weight through early and continuous prenatal care. Two key dimensions of the program were marketing and the use of volunteer neighborhood outreach workers. This paper explores the role of the program's public health nurses in relation to these dimensions and makes recommendations regarding marketing and use of outreach workers.

Developmental patterns of serum luteinizing hormone, gonadal and adrenal steroids in the sooty mangabey (Cercocebus atys)

Serum levels of luteinizing hormone (LH), testosterone, dehydroepiandrosterone sulfate (DHAS), androstenedione and cortisol were determined in multiple samples from 86 sooty mangabeys of varying ages (0-17 years). Testosterone, androstenedione, DHAS and cortisol were measured by radioimmunoassay; LH was determined by in vitro bioassay. Serum LH concentrations were elevated in neonates (less than 6 months) and in animals older than 72 months of age. The higher LH levels were associated with increased circulating concentrations of testosterone in males but not females. The pubertal rise in serum testosterone at approximately 55-60 months of age in males was coincident with rapid body growth. No pubertal growth spurt was observed in females. Serum levels of androstenedione and DHAS were highest during early postnatal life (less than 6 months) with androstenedione exceeding 600 ng/dl in males and 250 micrograms/dl in females, but declined rapidly in both sexes to a baseline of 150 ng/dl by 19 months of age. Serum androstenedione did not fluctuate significantly in adult animals. The pattern of age-related changes in serum DHAS paralleled those of serum androstenedione, whereas serum cortisol values did not change significantly with age. Developmental changes in serum LH, testosterone and body weight suggest that the sooty mangabey matures substantially later than the rhesus monkey. The pattern of serum gonadal and adrenal steroids during sexual maturation is similar to that seen in the baboon with no evidence of an adrenarche.