Mycophenolic acid-induced replication arrest, differentiation markers and cell death of androgen-independent prostate cancer cells DU145

Physicochemical Characterization and In Vitro Activity of Poly(ε-Caprolactone)/Mycophenolic Acid Amorphous Solid Dispersions

The obtention of amorphous solid dispersions (ASDs) of mycophenolic acid (MPA) in poly(ε-caprolactone) (PCL) is reported in this paper. An improvement in the bioavailability of the drug is possible thanks to the favorable specific interactions occurring in this system. Differential scanning calorimetry (DSC) was used to investigate the miscibility of PCL/MPA blends, measuring glass transition temperature (Tg) and analyzing melting point depression to obtain a negative interaction parameter, which indicates the development of favorable inter-association interactions. Fourier transform infrared spectroscopy (FTIR) was used to analyze the specific interaction occurring in the blends. Drug release measurements showed that at least 70% of the drug was released by the third day in vitro in all compositions. Finally, preliminary in vitro cell culture experiments showed a decreased number of cancerous cells over the scaffolds containing MPA, presumably arising from the anti-cancer activity attributable to MPA.

Synthesis and Biological Evaluation of Novel Anti-leukemia Proteolysis-Targeting Chimeras in Degradating Inosine Monophosphate Dehydrogenase

Background

Proteolysis-targeting chimera (PROTAC) is a bifunctional molecule comprising a ligand to recognize the targeted protein to be degraded.

Objectives

To use the advantages of the PROTAC technique, we have synthesized novel compounds to degrade inosine monophosphate dehydrogenase (IMPDH) by the proteasome system.

Methods

We describe the synthesis of new PROTACs based on a combination of mycophenolic acid (MPA) as the potent IMPDH inhibitor and pomalidomide as a ligand of E3 ubiquitin ligase via linkers formed from Cu(I)-catalyzed cycloaddition reaction.

Results

All synthesized compounds were investigated against Jurkat cells as acute T-cell leukemia and were potent apoptosis inducers at 50 nM.

Conclusion

The effect of compound 2 in 0.05 μM on IMPDH degradation can be almost prevented by competition with bortezomib as the proteasome inhibitor at 0.1 and 0.5 μM.

Synthesis, structural characterization, DFT calculations, molecular docking, and molecular dynamics simulations of a novel ferrocene derivative to unravel its potential antitumor activity

In this article, we describe a set of subsequent five-steps chemical reactions to synthesize a ferrocene derivative named 1-(5-(diphenylphosphaneyl)cyclopenta-1,3-dien-1-yl)ethyl)imino)-1,3-dihydroisobenzofuran-5-yl)methanol (compound 10). Structural characterization of 10 and its intermediate products was also performed and reported to attest to their formation. A molecular docking study was performed to propose the novel synthesized ferrocene derivative (10) as a potential antitumor candidate targeting the mitogen-activated protein (MAP) kinases interacting kinase (Mnk) 1. The computed docking score of (10) at -9.50 kcal/mol compared to the native anticancer staurosporine at -8.72 kcal/mol postulated a promising anticancer activity. Also, molecular dynamics (MD) simulations were carried out for 500 ns followed by MM-GBSA-binding free energy calculations for both the docked complexes of ferrocene and staurosporine to give more deep insights into their dynamic behavior in physiological conditions. Furthermore, DFT calculations were performed to unravel some of the physiochemical characteristics of the ferrocene derivative (10). The quantum mechanics calculations shed the light on some of the structural and electrochemical configurations of (10) which would open the horizon for further investigation. HighlightsThe synthesis of a ferrocene derivative named 1-(5-(diphenylphosphaneyl)cyclopenta-1,3-dien-1-yl)ethyl)imino)-1,3-dihydroisobenzofuran-5-yl)methanol (compound 10) was described.Structural characterizations of ferrocene derivative (10) and its intermediate products were also performed.DFT calculations, molecular docking, molecular dynamics, and MM-GBSA calculations were carried out.Computational studies revealed the antitumor potential of ferrocene derivative (10) through targeting and inhibiting mitogen-activated protein (MAP) kinases interacting kinase (Mnk) 1.Communicated by Ramaswamy H. Sarma.

Targeting NAD-dependent dehydrogenases in drug discovery against infectious diseases and cancer

Dehydrogenases are oxidoreductase enzymes that play a variety of fundamental functions in the living organisms and have primary roles in pathogen survival and infection processes as well as in cancer development. We review here a sub-set of NAD-dependent dehydrogenases involved in human diseases and the recent advancements in drug development targeting pathogen-associated NAD-dependent dehydrogenases. We focus also on the molecular aspects of the inhibition process listing the structures of the most relevant molecules targeting this enzyme family. Our aim is to review the most impacting findings regarding the discovery of novel inhibitory compounds targeting the selected NAD-dependent dehydrogenases involved in cancer and infectious diseases.

Reuse of Molecules for Glioblastoma Therapy

Glioblastoma multiforme (GBM) is a highly malignant primary brain tumor. The current standard of care for GBM is the Stupp protocol which includes surgical resection, followed by radiotherapy concomitant with the DNA alkylator temozolomide; however, survival under this treatment regimen is an abysmal 12-18 months. New and emerging treatments include the application of a physical device, non-invasive 'tumor treating fields' (TTFs), including its concomitant use with standard of care; and varied vaccines and immunotherapeutics being trialed. Some of these approaches have extended life by a few months over standard of care, but in some cases are only available for a minority of GBM patients. Extensive activity is also underway to repurpose and reposition therapeutics for GBM, either alone or in combination with the standard of care. In this review, we present select molecules that target different pathways and are at various stages of clinical translation as case studies to illustrate the rationale for their repurposing-repositioning and potential clinical use.

Therapeutic potential and molecular mechanisms of mycophenolic acid as an anticancer agent

Mycophenolic acid (MPA) is the active metabolite of mycophenolate mofetil (MMF), an immunosuppressive drug approved for the prophylaxis of allograft rejection in transplant recipients. Recent advances in the role of the type II isoform of inosine-5'-monophosphate dehydrogenase (IMPDH2) in the tumorigenesis of various types of cancer have called for a second look of MPA, the first IMPDH2 inhibitor discovered a hundred years ago, to be repurposed as an anticancer agent. Over a half century, a number of in vitro and in vivo experiments have consistently shown anticancer activity of MPA against several cell lines obtained from different malignancies and murine models. However, a few clinical trials have been conducted to investigate its anticancer activity in humans, and most of which have shown unsatisfactory results. Understanding of available evidence and underlying mechanism of action is a key step to be done so as to facilitate further investigations of MPA to reach its full therapeutic potential as an anticancer agent. This article provides a comprehensive review of non-clinical and clinical evidence available to date, with the emphasis on the molecular mechanism of action in which MPA exerts its anticancer activities: induction of apoptosis, induction of cell cycle arrest, and alteration of tumor microenvironment. Future perspective for further development of MPA to be an anticancer agent is extensively discussed, with the aim of translating the anticancer property of MPA from bench to bedside.

Synthesis and antifungal activities of 3-substituted phthalide derivatives

In order to obtain novel bioactive compounds with significant antifungal activities, two series of 3-substituted phthalide derivatives were designed and synthesized via reduction, bromine substitution, and etherification. In addition, the antifungal activities of all target compounds against nine phytopathogenic fungi in vitro were tested by using the mycelial growth rate method at the concentration of 50 μg mL−1. Preliminary bioassay tests showed that some compounds exhibited more potent antifungal activities as compared with hymexazol. The preliminary structure-activity relationships (SARs) of all target compounds were also investigated.

Anti-Tumor Potential of IMP Dehydrogenase Inhibitors: A Century-Long Story

The purine nucleotides ATP and GTP are essential precursors to DNA and RNA synthesis and fundamental for energy metabolism. Although de novo purine nucleotide biosynthesis is increased in highly proliferating cells, such as malignant tumors, it is not clear if this is merely a secondary manifestation of increased cell proliferation. Suggestive of a direct causative effect includes evidence that, in some cancer types, the rate-limiting enzyme in de novo GTP biosynthesis, inosine monophosphate dehydrogenase (IMPDH), is upregulated and that the IMPDH inhibitor, mycophenolic acid (MPA), possesses anti-tumor activity. However, historically, enthusiasm for employing IMPDH inhibitors in cancer treatment has been mitigated by their adverse effects at high treatment doses and variable response. Recent advances in our understanding of the mechanistic role of IMPDH in tumorigenesis and cancer progression, as well as the development of IMPDH inhibitors with selective actions on GTP synthesis, have prompted a reappraisal of targeting this enzyme for anti-cancer treatment. In this review, we summarize the history of IMPDH inhibitors, the development of new inhibitors as anti-cancer drugs, and future directions and strategies to overcome existing challenges.

Diels-Alder and Stille Coupling Approach for the Short Protecting-Group-Free Synthesis of Mycophenolic Acid, Its Phenylsulfenyl and Phenylselenyl Analogues, and Reactive Oxygen Species (ROS) Probing Capacity in Water

A short, protecting-group-free synthesis is achieved. The synthesis is step-efficient and general. A Diels-Alder and Stille cross-coupling approach includes key transformations, allowing for a competitive synthesis which involves a rare halophenol Stille cross-coupling study. The phenylselenyl and phenylsulfenyl analogues were prepared as novel compounds in good overall yield. The applicability of one of the intermediates as a potential probe for reactive oxygen species (ROS) in water is investigated.

Identifying drug-pathway association pairs based on L2,1-integrative penalized matrix decomposition

BACKGROUND

Traditional drug identification methods follow the "one drug-one target" thought. But those methods ignore the natural characters of human diseases. To overcome this limitation, many identification methods of drug-pathway association pairs have been developed, such as the integrative penalized matrix decomposition (iPaD) method. The iPaD method imposes the L₁-norm penalty on the regularization term. However, lasso-type penalties have an obvious disadvantage, that is, the sparsity produced by them is too dispersive.

RESULTS

Therefore, to improve the performance of the iPaD method, we propose a novel method named L_2,1-iPaD to identify paired drug-pathway associations. In the L_2,1-iPaD model, we use the L_2,1-norm penalty to replace the L₁-norm penalty since the L_2,1-norm penalty can produce row sparsity.

CONCLUSIONS

By applying the L_2,1-iPaD method to the CCLE and NCI-60 datasets, we demonstrate that the performance of L_2,1-iPaD method is superior to existing methods. And the proposed method can achieve better enrichment in terms of discovering validated drug-pathway association pairs than the iPaD method by performing permutation test. The results on the two real datasets prove that our method is effective.

Dual or multi-targeting inhibitors: The next generation anticancer agents

Dual-targeting/Multi-targeting of oncoproteins by a single drug molecule represents an efficient, logical and alternative approach to drug combinations. An increasing interest in this approach is indicated by a steady upsurge in the number of articles on targeting dual/multi proteins published in the last 5 years. Combining different inhibitors that destiny specific single target is the standard treatment for cancer. A new generation of dual or multi-targeting drugs is emerging, where a single chemical entity can act on multiple molecular targets. Dual/Multi-targeting agents are beneficial for solving limited efficiencies, poor safety and resistant profiles of an individual target. Designing dual/multi-target inhibitors with predefined biological profiles present a challenge. The latest advances in bioinformatic tools and the availability of detailed structural information of target proteins have shown a way of discovering multi-targeting molecules. This neoteric artifice that amalgamates the molecular docking of small molecules with protein-based common pharmacophore to design multi-targeting inhibitors is gaining great importance in anticancer drug discovery. Current review focus on the discoveries of dual targeting agents in cancer therapy using rational, computational, proteomic, bioinformatics and polypharmacological approach that enables the discovery and rational design of effective and safe multi-target anticancer agents.

Nanomedicine for prostate cancer using nanoemulsion: A review

Prostate cancer (PCa) is a worldwide issue, with burgeoning rise in prevalence, morbidity and mortality. Targeted drug delivery, a long sort solution in this regard using controlled release (CR) - nanocarriers, is still a challenge. There is an emerging criticism that, the challenges are due to less appreciation for the biological barriers and lack of corresponding newer technologies. Over the years, more understanding about the biological barriers has come with the progress in characterization techniques. Correspondingly, there is a change in opinion about approaches in clinical trial that; focus of the end point need to be shifted towards disease stabilization for these explorative technologies. Currently, there is a requirement to overcome these newly identified challenges to develop newer affordable therapeutics. The ongoing clinical protocol for therapy using CR-nanocarriers is intravenous injection followed by local targeting to cancer site. This is the most accepted protocol and new CR-nanocarriers are being developed to suit this protocol. In this review, recent progress in treatment of PCa using CR-nanocarriers is analyzed with respect to newly identified biological barriers and design challenges. Possibilities of exploring nanoemulsion (NE) platform for targeted drug delivery to PCa are examined. Repurposing of drugs and combination therapy using NE platform targeted to PCa can be explored for design and development of affordable nanomedicine. In 20yrs. from now there expected to be numerous affordable nanomedicine technologies available in market exploring these lines.

Rapid and selective synthesis of spiropyrazolines and pyrazolylphthalides employing Seyferth–Gilbert reagent

An efficient protocol for the selective synthesis of spiropyrazoline phosphonates and pyrazolylphthalides employing Seyferth–Gilbert reagent is reported.

Serum depletion induces changes in protein expression in the trophoblast-derived cell line HTR-8/SVneo

BACKGROUND

How nutrition and growth factor restriction due to serum depletion affect trophoblast function remains poorly understood. We performed a proteomic differential study of the effects of serum depletion on a first trimester human immortalized trophoblast cell line.

METHODS

The viability of HTR-8/SVneo trophoblast cells in culture with 0, 0.5 and 10 % fetal bovine serum (FBS) were assayed via MTT at 24, 48 and 64 h. A comparative proteomic analysis of the cells grown with those FBS levels for 24 h was performed using two-dimensional electrophoresis (2DE), followed by mass spectrometry for protein spot identification, and a database search and bioinformatics analysis of the expressed proteins. Differential spots were identified using the Kolmogorov-Smirnov test (n = 3, significance level 0.10, D > 0.642) and/or ANOVA (n = 3, p < 0.05).

RESULTS

The results showed that low serum doses or serum depletion differentially affect cell growth and protein expression. Differential expression was seen in 25 % of the protein spots grown with 0.5 % FBS and in 84 % of those grown with 0 % FBS, using 10 % serum as the physiological control. In 0.5 % FBS, this difference was related with biological processes typically affected by the serum, such as cell cycle, regulation of apoptosis and proliferation. In addition to these changes, in the serum-depleted proteome we observed downregulation of keratin 8, and upregulation of vimentin, the glycolytic enzymes enolase and pyruvate kinase (PKM2) and tumor progression-related inosine-5'-monophosphate dehydrogenase 2 (IMPDH2) enzyme. The proteins regulated by total serum depletion, but not affected by growth in 0.5 % serum, are members of the glycolytic and nucleotide metabolic pathways and the epithelial-to-mesenchymal transition (EMT), suggesting an adaptive switch characteristic of malignant cells.

CONCLUSIONS

This comparative proteomic analysis and the identified proteins are the first evidence of a protein expression response to serum depletion in a trophoblast cell model. Our results show that serum depletion induces specific changes in protein expression concordant with main cell metabolic adaptations and EMT, resembling the progression to a malignant phenotype.

Neural cells play an inhibitory role in pancreatic differentiation of pluripotent stem cells

Pancreatic endocrine β-cells derived from embryonic stem (ES) cells and induced pluripotent stem (iPS) cells have received attention as screening systems for therapeutic drugs and as the basis for cell-based therapies. Here, we used a 12-day β-cell differentiation protocol for mouse ES cells and obtained several hit compounds that promoted β-cell differentiation. One of these compounds, mycophenolic acid (MPA), effectively promoted ES cell differentiation with a concomitant reduction of neuronal cells. The existence of neural cell-derived inhibitory humoral factors for β-cell differentiation was suggested using a co-culture system. Based on gene array analysis, we focused on the Wnt/β-catenin pathway and showed that the Wnt pathway inhibitor reversed MPA-induced β-cell differentiation. Wnt pathway activation promoted β-cell differentiation also in human iPS cells. Our results showed that Wnt signaling activation positively regulates β-cell differentiation, and represent a downstream target of the neural inhibitory factor.

A Review of the Potential Utility of Mycophenolate Mofetil as a Cancer Therapeutic

Tumor cells adapt to their high metabolic state by increasing energy production. To this end, current efforts in molecular cancer therapeutics have been focused on signaling pathways that modulate cellular metabolism. However, targeting such signaling pathways is challenging due to heterogeneity of tumors and recurrent oncogenic mutations. A critical need remains to develop antitumor drugs that target tumor specific pathways. Here, we discuss an energy metabolic pathway that is preferentially activated in several cancers as a potential target for molecular cancer therapy. In vitro studies have revealed that many cancer cells synthesize guanosine triphosphate (GTP), via the de novo purine nucleotide synthesis pathway by upregulating the rate limiting enzyme of this pathway, inosine monophosphate dehydrogenase (IMPDH). Non-proliferating cells use an alternative purine nucleotide synthesis pathway, the salvage pathway, to synthesize GTP. These observations pose IMPDH as a potential target to suppress tumor cell growth. The IMPDH inhibitor, mycophenolate mofetil (MMF), is an FDA-approved immunosuppressive drug. Accumulating evidence shows that, in addition to its immunosuppressive effects, MMF also has antitumor effects via IMPDH inhibition in vitro and in vivo. Here, we review the literature on IMPDH as related to tumorigenesis and the use of MMF as a potential antitumor drug.

Trend of histone deacetylase inhibitors in cancer therapy: isoform selectivity or multitargeted strategy

Pharmacological inhibition of histone deacetylases (HDACs) has been successfully applied in the treatment of a wide range of disorders, including Parkinson's disease, infection, cardiac diseases, inflammation, and especially cancer. HDAC inhibitors (HDACIs) have been proved to be effective antitumor agents by various stages of investigation. At present, there are two opposite focuses of HDACI design in the cancer therapy, highly selective inhibitor strategy and dual- or multitargeted inhibitors. The former method, which is supposed to elucidate the function of individual HDAC and provide candidate inhibitors with fewer side effects, has been widely accepted by the inhibitor developer. The latter approach, though less practiced, has promising potential for the antitumor therapy based on HDACIs. Effective HDACIs, some of which are in clinic anticancer research, have been developed by both methods. In order to gain insight into HDACI design, the strategies and achievements of the two diverse methods are reviewed.

NAD-based inhibitors with anticancer potential

Three classes of novel inhibitors of inosine monophosphate dehydrogenase have been prepared and their anti-proliferative properties were evaluated against several cancer cell lines. (1) Mycophenolic adenine dinucleotide analogues (8-13) containing a substituent at the C2 of adenine ring were found to be potent inhibitors of IMPDH (Ki's in range of 0.6-82nM) and sub-μM inhibitors of leukemic K562 cell proliferation. (2) Mycophenolic adenosine (d and l) esters (20 and 21) showed a potent inhibition of IMPDH2 (Ki=102 and Ki=231nM, respectively) and inhibition of K562 cell growth (IC50=0.5 and IC50=1.6μM). These compounds serve both as inhibitors of the enzyme and as a depot form of mycophenolic acid. The corresponding amide analogue 22, also a potent inhibitor of IMPDH (Ki=84nM), did not inhibit cancer cell proliferation. (3) Mycophenolic-(l)- and (d)-valine adenine di-amide derivatives 25 (Ki=9nM) and 28 (Ki=3nM) were found to be very potent enzymatically, but did not inhibit proliferation of cancer cells.

Advanced prostate cancer--a case for adjuvant differentiation therapy

The development of novel therapies such as abiraterone acetate and sipuleucel-T has improved the outlook for patients with advanced-stage and castration-resistant prostate cancer. However, the beneficial effects of these drugs are only measured in months. Moreover, the National Institute for Health and Clinical Excellence in the UK had ruled that the use of abiraterone acetate was not cost-effective before cost revision by the manufacturers. The FDA statement asserting that the use of 5α-reductase inhibitors for prostate cancer chemoprevention could increase the risk of developing high-grade prostate cancer also indirectly questions the value of direct androgen response manipulation for long-term benefit. These reports illustrate the need for a fresh and comprehensive analysis of advanced prostate cancer pathology to promote the next generation of effective adjuvant therapies. One such avenue is that of differentiation therapy, which seeks to promote the differentiation of cancer stem cells into a phenotype more sensitive to anticancer therapy than their parents. Using differentiation therapy with current antiandrogen therapies should augment our armoury of treatment for the management of advanced prostate cancer.

Mycophenolic Acid overcomes imatinib and nilotinib resistance of chronic myeloid leukemia cells by apoptosis or a senescent-like cell cycle arrest

We used K562 cells sensitive or generated resistant to imatinib or nilotinib to investigate their response to mycophenolic acid (MPA). MPA induced DNA damage leading to cell death with a minor contribution of apoptosis, as revealed by annexin V labeling (up to 25%). In contrast, cell cycle arrest and positive staining for senescence-associated β-galactosidase activity were detected for a large cell population (80%). MPA-induced cell death was potentialized by the inhibition of autophagy and this is associated to the upregulation of apoptosis. In contrast, senescence was neither decreased nor abrogated in autophagy deficient K562 cells. Primary CD34 cells from CML patients sensitive or resistant to imatinib or nilotinib respond to MPA although apoptosis is mainly detected. These results show that MPA is an interesting tool to overcome resistance in vitro and in vivo mainly in the evolved phase of the disease.

The design, synthesis and in vitro immunosuppressive evaluation of novel isobenzofuran derivatives

The synthesis and biological evaluation of a series of novel isobenzofuran-based compounds are described. The compounds were evaluated for their immunosuppressive effects of T-cell proliferation and IMPDH type II inhibitor activity in vitro, as well as their structure-activity relationships were assessed. Several compounds demonstrated highly efficacious immunosuppressive properties, especially compounds 2d, 2e, 2h and 2j, which were superior to MPA, while compounds 2k, 2m, 2n, 4c and 5d exhibited an equipotent inhibitory activity compared to MPA. Generally, it was obviously demonstrated that α,β-unsaturated amides proved more potent than the diamide and urea series. The present study provides a guide for further research on development of safe and effective immunosuppressive agents.

Mycophenolic acid induces adipocyte-like differentiation and reversal of malignancy of breast cancer cells partly through PPARγ

Mycophenolic acid (MPA) has been known for decades to be an anticancer and immunosuppressive agent and has significant anticancer properties, but its underlying molecular mechanisms are poorly characterized. Peroxisome proliferator-activated receptor gamma (PPARγ) has a central role in adipocyte differentiation, and MPA has been shown to be a potent PPARγ agonist. Whether PPARγ activation has a putative role in the anticancer efficacy of MPA via induction of adipocyte-like differentiation has not been elucidated. In the present study, MPA was demonstrated to dose-dependently activate PPARγ transcription in the GAL4-hPPARγ (LBD) chimeric receptor assay and PPRE-luc reporter gene assay with an EC(50) of 5.2-9.3 μM. Treatment of the breast cancer cell lines MDA-MB-231 and MCF-7 with MPA resulted in differentiation of adipose tissue that was characterized by accumulation of intracellular lipids, enlargement of cell volume, and permanent withdrawal from the cell cycle at the G1/G0 stage. At a molecular level, the expression of three adipocyte differentiation markers (PPARγ, adipsin D, and aP2) was remarkably induced in differentiated breast cancer cells. However, RNA interference experiments showed that PPARγ-knockdown cannot completely reverse the differentiated state of MDA-MB-231 cells after MPA treatment. These data suggest that the effects of MPA on adipocyte-like terminal differentiation of breast cancer cells are (at least in part) due to PPARγ activation, which is a novel anticancer mechanism of MPA.

Antiproliferative effects of AVN944, a novel inosine 5-monophosphate dehydrogenase inhibitor, in prostate cancer cells

Inosine 5-monophosphate dehydrogenase II, a key enzyme in the de novo synthesis of purine nucleotides, is expressed in prostate tumors and prostate cancer cells. AVN944 is a new, specific, noncompetitive IMPDH inhibitor. In this study, we investigated the effects of IMPDH inhibitor AVN944 on LNCaP, CWR22Rv1, DU145 and PC-3 human prostate cancer cells. AVN944 inhibited proliferation of these 4 prostate cancer cell lines and was associated with cell cycle G1 arrest of LNCaP cells and S-phase block of androgen-independent CWR22Rv1, DU145 and PC-3 cells. AVN944 induced caspase-dependentand caspase-independent cell death in LNCaP, CWR22Rv1, and DU145 cells. AVN944 induced expression of p53-target proteins Bok, Bax and Noxa in androgen-responsive cell lines and suppressed expression of survivin in prostate cancer cells regardless of their androgen sensitivity. AVN944 also induced differentiation of androgen-independent prostate cancer cells as indicated by morphological changes and increased expression of genes coding for prostasomal proteins, keratins and other proteins, including tumor suppressor genes MIG-6 and NDRG1. AVN944-differentiated androgen-independent DU145 and PC-3 cells are sensitized to TRAIL-induced apoptosis as demonstrated by induction of caspases and PARP cleavage. In summary, AVN944 inhibited the growth of human prostate cancer cells by inducing cell cycle arrest, cell death as well as differentiation. AVN944 is a novel, promising therapeutic agent that might be combined with other agents for treatment of human prostate cancer.

Molecular mechanisms of the antiangiogenic and antitumor effects of mycophenolic acid

The relative risk for the development of malignancies following solid organ transplantation seems to be decreased in patients treated with the immunosuppressive agent mycophenolic acid (MPA). However, the molecular mechanisms of the antineoplastic effects of MPA are not completely understood. Here, we report that human endothelial cells and fibroblasts are highly sensitive to MPA treatment. We found that U87 glioblastoma cells were resistant to MPA treatment in vitro. However, U87 tumor growth was markedly inhibited in vivo in BALB/c nude mice, suggesting that MPA exerted its antitumor effects via modulation of the tumor microenvironment. Accordingly, microvascular density and pericyte coverage were markedly reduced in MPA-treated tumors in vivo. Using functional in vitro assays, we showed that MPA potently inhibited endothelial cell and fibroblast proliferation, invasion/migration, and endothelial cell tube formation. To identify the genetic participants governing the antiangiogenic and antifibrotic effects of MPA, we performed genome-wide transcriptional analysis in U87, endothelial and fibroblast cells at 6 and 12 h after MPA treatment. Network analysis revealed a critical role for MYC signaling in endothelial cells treated with MPA. Moreover, we found that the antiangiogenic effects of MPA were organized by coordinated communications between MYC and NDRG1, YYI, HIF1A, HDAC2, CDC2, GSK3B, and PRKACB signaling. The regulation of these "hub nodes" was confirmed by real-time quantitative reverse transcription-PCR and protein analysis. The critical involvement of MYC in the antiangiogenic signaling of MPA was further shown by gene knockdown experiments. Together, these data provide a molecular basis for the antiangiogenic and antifibrotic effects of MPA, which warrants further clinical investigations.

Perifosine induces differentiation and cell death in prostate cancer cells

We analyzed the mechanism of action for perifosine (D-21266), a new synthetic alkylphospholipid Akt inhibitor, using LNCaP and PC-3 prostate cancer cells. Perifosine treatment of PC-3 cells resulted in cytostatic and cytotoxic effects. Cytostatic effects were characterized by cell growth arrest, cell cycle block, and morphological changes, such as a cell enlargement and granulation, hallmarks of differentiating PC-3 cells. Specific differentiation markers including prostasomal, secretory and plasma membrane proteins, and keratins were induced by perifosine. Among them, we detected strong induction and secretion of CEACAM5 protein. In contrast, perifosine strongly reduced caveolin-1 RNA levels. Cytotoxic effects included para-apoptosis, apoptosis, and necrosis. To pursue the mechanisms responsible for these activities we focused on signaling pathways that lie downstream of Akt. Perifosine-triggered GSK-3beta activation in PC-3 and LNCaP cells resulted in the expression of GSK-3beta-related differentiation markers. This expression was reduced in the presence of specific siRNA for GSK-3beta or for its target CREB protein. The use of the GSK-3beta inhibitor lithium chloride indicated that GSK-3beta partially protects prostate cancer cells from the cytotoxic effects of perifosine. Together, these findings indicate that perifosine induces GSK-3beta-related differentiation and caspase-independent cell death in prostate cancer PC-3 cells. In addition our results identify specific biomarkers for perifosine therapy.

Dual inhibitors of inosine monophosphate dehydrogenase and histone deacetylases for cancer treatment

Mycophenolic acid (MPA), an inhibitor of IMP-dehydrogenase (IMPDH), is used worldwide in transplantation. Recently, numerous studies showed its importance in cancer treatment. Consequently, MPA entered clinical trials in advanced multiple myeloma patients. Suberoylanilide hydroxamic acid (SAHA), a potent differentiation agent acting through inhibition of histone deacetylases (HDACs), was recently approved for treatment of cutaneous T cell lymphoma. We report herein the synthesis of dual inhibitors of IMPDH and HDACs. We found that mycophenolic hydroxamic acid (9, MAHA) inhibits both IMPDH (Ki=30 nM) and HDAC (IC50=5.0 microM). A modification of SAHA with groups known to interact with IMPDH afforded a SAHA analogue 14, which inhibits IMPDH (Ki=1.7 microM) and HDAC (IC50=0.06 microM). Both MAHA (IC50=4.8 microM) and SAHA analogue 14 (IC50=7.7 microM) were more potent than parent compounds as antiproliferation agents. They were also significantly more potent as differentiation inducers.