The Secretome Analysis of Activated Human Renal Fibroblasts Revealed Beneficial Effect of the Modulation of the Secreted Peptidyl-Prolyl Cis-Trans Isomerase A in Kidney Fibrosis

The secretome is an important mediator in the permanent process of reciprocity between cells and their environment. Components of secretome are involved in a large number of physiological mechanisms including differentiation, migration, and extracellular matrix modulation. Alteration in secretome composition may therefore trigger cell transformation, inflammation, and diseases. In the kidney, aberrant protein secretion plays a central role in cell activation and transition and in promoting renal fibrosis onset and progression. Using comparative proteomic analyses, we investigated in the present study the impact of cell transition on renal fibroblast cells secretome. Human renal cell lines were stimulated with profibrotic hormones and cytokines, and alterations in secretome were investigated using proteomic approaches. We identified protein signatures specific for the fibrotic phenotype and investigated the impact of modeling secretome proteins on extra cellular matrix accumulation. The secretion of peptidyl-prolyl cis-trans isomerase A (PPIA) was demonstrated to be associated with fibrosis phenotype. We showed that the in-vitro inhibition of PPIA with ciclosporin A (CsA) resulted in downregulation of PPIA and fibronectin (FN1) expression and significantly reduced their secretion. Knockdown studies of PPIA in a three-dimensional (3D) cell culture model significantly impaired the secretion and accumulation of the extracellular matrix (ECM), suggesting a positive therapeutic effect on renal fibrosis progression.

Cyclophilins and cyclophilin inhibitors in nidovirus replication

Cyclophilins (Cyps) belong to the family of peptidyl-prolyl isomerases (PPIases). The PPIase activity of most Cyps is inhibited by the immunosuppressive drug cyclosporin A and several of its non-immunosuppressive analogs, which can also block the replication of nidoviruses (arteriviruses and coronaviruses). Cyclophilins have been reported to play an essential role in the replication of several other RNA viruses, including human immunodeficiency virus-1, hepatitis C virus, and influenza A virus. Likewise, the replication of various nidoviruses was reported to depend on Cyps or other PPIases. This review summarizes our current understanding of this class of nidovirus-host interactions, including the potential function of in particular CypA and the inhibitory effect of Cyp inhibitors. Also the involvement of the FK-506-binding proteins and parvulins is discussed. The nidovirus data are placed in a broader perspective by summarizing the most relevant data on Cyp interactions and Cyp inhibitors for other RNA viruses.

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Nidovirus replication is inhibited by cyclophilin inhibitors.

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Arterivirus replication depends on cyclophilin A.

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Cyclosporin A blocks arterivirus RNA synthesis.

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Using cyclophilin inhibitors against nidoviruses in vivo needs more investigation.

Targeting the molecular chaperone SlyD to inhibit bacterial growth with a small molecule

Molecular chaperones are essential molecules for cell growth, whereby they maintain protein homeostasis. Because of their central cellular function, bacterial chaperones might be potential candidates for drug targets. Antimicrobial resistance is currently one of the greatest threats to human health, with gram-negative bacteria being of major concern. We found that a Cu2+ complex readily crosses the bacterial cell wall and inhibits SlyD, which is a molecular chaperone, cis/trans peptidyl prolyl isomerise (PPIase) and involved in various other metabolic pathways. The Cu2+ complex binds to the active sites of SlyD, which suppresses its PPIase and chaperone activities. Significant cell growth retardation could be observed for pathogenic bacteria (e.g., Staphylococcus aureus and Pseudomonas aeruginosa). We anticipate that rational development of drugs targeting molecular chaperones might help in future control of pathogenic bacterial growth, in an era of rapidly increasing antibiotic resistance.

Brown Algae Polyphenol, a Prolyl Isomerase Pin1 Inhibitor, Prevents Obesity by Inhibiting the Differentiation of Stem Cells into Adipocytes

BACKGROUND

While screening for an inhibitor of the peptidyl prolyl cis/trans isomerase, Pin1, we came across a brown algae polyphenol that blocks the differentiation of fibroblasts into adipocytes. However, its effectiveness on the accumulation of fat in the body has never been studied.

METHODOLOGY/PRINCIPAL FINDINGS

Oral administration of brown algae polyphenol to mice fed with a high fat diet, suppressed the increase in fat volume to a level observed in mice fed with a normal diet. We speculate that Pin1 might be required for the differentiation of stem cell to adipocytes. We established wild type (WT) and Pin1-/- (Pin1-KO) adipose-derived mesenchymal stem cell (ASC) lines and found that WT ASCs differentiate to adipocytes but Pin1-KO ASCs do not.

CONCLUSION AND SIGNIFICANCE

Oral administration of brown algae polyphenol, a Pin1 inhibitor, reduced fat buildup in mice. We showed that Pin1 is required for the differentiation of stem cells into adipocytes. We propose that oral intake of brown algae polyphenol is useful for the treatment of obesity.

FRET-Protease-Coupled Peptidyl-Prolyl cis-trans Isomerase Assay: New Internally Quenched Fluorogenic Substrates for High-Throughput Screening

In this work, a sensitive and convenient protease-based fluorimetric high-throughput screening (HTS) assay for determining peptidyl-prolyl cis-trans isomerase activity was developed. The assay was based on a new intramolecularly quenched substrate, whose fluorescence and structural properties were examined together with kinetic constants and the effects of solvents on its isomerization process. Pilot screens performed using the Library of Pharmacologically Active Compounds (LOPAC) and cyclophilin A (CypA), as isomerase model enzyme, indicated that the assay was robust for HTS, and that comparable results were obtained with a CypA inhibitor tested both manually and automatically. Moreover, a new compound that inhibits CypA activity with an IC50 in the low micromolar range was identified. Molecular docking studies revealed that the molecule shows a notable shape complementarity with the catalytic pocket confirming the experimental observations. Due to its simplicity and precision in the determination of extent of inhibition and reaction rates required for kinetic analysis, this assay offers many advantages over other commonly used assays.

Peptidyl prolyl isomerase Pin1-inhibitory activity of D-glutamic and D-aspartic acid derivatives bearing a cyclic aliphatic amine moiety

Pin1 is a peptidyl prolyl isomerase that specifically catalyzes cis-trans isomerization of phosphorylated Thr/Ser-Pro peptide bonds in substrate proteins and peptides. Pin1 is involved in many important cellular processes, including cancer progression, so it is a potential target of cancer therapy. We designed and synthesized a novel series of Pin1 inhibitors based on a glutamic acid or aspartic acid scaffold bearing an aromatic moiety to provide a hydrophobic surface and a cyclic aliphatic amine moiety with affinity for the proline-binding site of Pin1. Glutamic acid derivatives bearing cycloalkylamino and phenylthiazole groups showed potent Pin1-inhibitory activity comparable with that of known inhibitor VER-1. The results indicate that steric interaction of the cyclic alkyl amine moiety with binding site residues plays a key role in enhancing Pin1-inhibitory activity.

Pin1 Inhibitor Juglone Exerts Anti-Oncogenic Effects on LNCaP and DU145 Cells despite the Patterns of Gene Regulation by Pin1 Differing between These Cell Lines

Background

Prostate cancer initially develops in an androgen-dependent manner but, during its progression, transitions to being androgen-independent in the advanced stage. Pin1, one of the peptidyl-prolyl cis/trans isomerases, is reportedly overexpressed in prostate cancers and is considered to contribute to accelerated cell growth, which may be one of the major factors contributing to their androgen-independent growth. Thus, we investigated how Pin1 modulates the gene expressions in both androgen-dependent and androgen-independent prostate cancer cell lines using microarray analysis. In addition, the effects of Juglone, a commercially available Pin1 inhibitor were also examined.

Methods

Two prostate cancer cell-lines, LNCaP (androgen-dependent) and DU145 (androgen-independent), were treated with Pin1 siRNA and its effects on gene expressions were analyzed by microarray. Individual gene regulations induced by Pin1 siRNA or the Pin1 inhibitor Juglone were examined using RT-PCR. In addition, the effects of Juglone on the growth of LNCaP and DU145 transplanted into mice were investigated.

Results

Microarray analysis revealed that transcriptional factors regulated by Pin1 differed markedly between LNCaP and DU145 cells, the only exception being that Nrf was regulated in the same way by Pin1 siRNA in both cell lines. Despite this marked difference in gene regulations, Pin1 siRNA and Juglone exert a strong inhibitory effect on both the LNCaP and the DU145 cell line, suppressing in vitro cell proliferation as well as tumor enlargement when transplanted into mice.

Conclusions

Despite Pin1-regulated gene expressions differing between these two prostate cancer cell-lines, LNCaP (androgen-dependent) and DU145 (androgen-independent), Pin1 inhibition suppresses proliferation of both cell-lines. These findings suggest the potential effectiveness of Pin1 inhibitors as therapeutic agents for prostate cancers, regardless of their androgen sensitivity.

Rosacea-like eruption due to topical pimecrolimus

Topical calcineurin inhibitors have been used outside their approved indications for a number of conditions, including topical steroid-induced rosacea. However, tacrolimus ointment itself has been reported to trigger rosacea in a small number of cases. We report a case of a rosacea-like eruption in a 39-year-old woman occurring after the use of pimecrolimus cream for 12 months for atopic dermatitis. Withdrawal of pimecrolimus combined with treatment with oral lymecycline, topical metronidazole, and an emollient resulted in resolution of the eruption. There have been 5 previously reported cases of a topical pimecrolimus-induced rosacea-like eruption suggesting that this rare side-effect may be a class effect of all topical calcineurin inhibitors. Dermatologists prescribing these drugs should be aware of this uncommon complication and may wish to warn patients of its occurrence as a potential side-effect when using topical calcineurin inhibitors in facial skin in adults.

Multiple labial melanotic macules occurring after topical application of calcineurin inhibitors

Topical calcineurin inhibitors are widely used to treat inflammatory dermatoses for their steroid-sparing advantage. Herein, we report a patient with chronic lip dermatitis who developed multiple labial melanotic macules after application of tacrolimus 0.1% ointment and pimecrolimus 1% cream. Prior and current reports raise concerns for potential development of pigmented lesions associated with topical calcineurin inhibitor use. These reports highlight the need for careful risk-benefit assessment when prescribing topical calcineurin inhibitors for inflammatory dermatoses, especially when used on sun-exposed sites.

Structure-based design of novel human Pin1 inhibitors (III): optimizing affinity beyond the phosphate recognition pocket

The design of potent Pin1 inhibitors has been challenging because its active site specifically recognizes a phospho-protein epitope. The de novo design of phosphate-based Pin1 inhibitors focusing on the phosphate recognition pocket and the successful replacement of the phosphate group with a carboxylate have been previously reported. The potency of the carboxylate series is now further improved through structure-based optimization of ligand-protein interactions in the proline binding site which exploits the H-bond interactions necessary for Pin1 catalytic function. Further optimization using a focused library approach led to the discovery of low nanomolar non-phosphate small molecular Pin1 inhibitors. Structural modifications designed to improve cell permeability resulted in Pin1 inhibitors with low micromolar anti-proliferative activities against cancer cells.

Cell-permeable bicyclic peptide inhibitors against intracellular proteins

Cyclic peptides have great potential as therapeutic agents and research tools but are generally impermeable to the cell membrane. Fusion of cyclic peptides with a cyclic cell-penetrating peptide produces bicyclic peptides that are cell-permeable and retain the ability to recognize specific intracellular targets. Application of this strategy to protein tyrosine phosphatase 1B and a peptidyl-prolyl cis-trans isomerase (Pin1) isomerase resulted in potent, selective, proteolytically stable, and biologically active inhibitors against the enzymes.

[Application of temperature sensitive yeast models with definite target in the screening of potential human Pin1 inhibitors]

This study is to explore new lead compounds by inhibition of Pin1 for anticancer therapy using temperature sensitive mutants. As Pin1 is conserved from yeast to human, we established a high-throughput screening method for Pin1 inhibitors, which employed yeast assay. This method led to the identification of one potent hits, 8-11. In vitro, 8-11 inhibited purified Pin1 enzyme activity with IC50 of (10.40 +/- 1.68) micromol x L(-1), induced G1 phase arrest and apoptosis, showed inhibitory effects on a series of cancer cell proliferation, reduced Cyclin D1 expression, was defined as reciprocally matched for protein-ligand complex in virtual docking analysis and reduced cell migration ability. In vivo, we could observe reduction of tumor volume after treatment with 8-11 in xenograft mice compared with vehicle DMSO treatment. Altogether, these results provide for the first time the involvement of 8-11 in the anticancer activity against Pin1.

Prolyl-isomerase Pin1 impairs trastuzumab sensitivity by up-regulating fatty acid synthase expression

BACKGROUND/AIM

Clinical trials have shown efficacy of the anti-HER2 monoclonal antibody trastuzumab in metastatic breast cancer patients. The aim of the present study was to elucidate the mechanisms by which up-regulation of fatty acid synthase (FAS) expression confers resistance to trastuzumab in HER2-positive breast cancers.

MATERIALS AND METHODS

The expression of FAS as well as the cytotoxic effects of combinatorial treatment of trastuzumab and juglone was investigated by immunoblotting, BrdU incorporation, TUNEL assay, and soft agar assay.

RESULTS

Pin1 enhanced EGF-induced SREBP1c promoter activity, resulting in the induction of FAS expression in BT474 cells. In contrast, juglone, a potent Pin1 inhibitor, significantly enhanced trastuzumab-induced FAS down-regulation and cell death in BT474 cells. Furthermore, trastuzumab, when used in combination with gene silencing or chemical inhibition of Pin1, increased cleaved poly(ADP-ribose) polymerase and DNA fragmentation to increase trastuzumab sensitivity.

CONCLUSION

Pin1-mediated FAS overexpression is a major regulator of trastuzumab-resistant breast cancer growth and survival.

[The interference effect of lentiviral mediated shRNA on the expression of Pin 1 in A549 cells]

OBJECTIVE

To construct a Pin1shRNA lentiviral vector and transfect stably A549 cells.

METHODS

The peptidyl-proplyl cis-trans isomerase 1(Pin1) gene sequences from GenBank were cloned into the pLenR-GPH-shRNA lentiviral vector. The pLenR-GPH-shRNA and lentivector pakaging plasmid mix were cotransfected into human embryonic kidney cells HEK293T to package lentiviral particles. The virus supernatant was harvested, and then the virus titer was determined by serial dilution assay. The A549 cells were transduced with the constructed lentiviral vectors. Real-time quantitative PCR (qRT-PCR) and Western blotting were used to evaluate the Pin1 expression in different groups.

RESULTS

Restriction enzyme analysis and sequencing demonstrated that the recombinant plasmid named pLenR-GPH-Pin1shRNA was successfully prepared and had a high titer. qRT-PCR and Western blotting revealed that the significant down-regulation of Pin1 expression in A549 cells.

CONCLUSION

The lentiviral mediated shRNA can effectively down-regulate the expression of Pin 1 in A549 cells.

The prolyl isomerase pin1 regulates mRNA levels of genes with short half-lives by targeting specific RNA binding proteins

The peptidyl-prolyl isomerase Pin1 is over-expressed in several cancer tissues is a potential prognostic marker in prostate cancer, and Pin1 ablation can suppress tumorigenesis in breast and prostate cancers. Pin1 can co-operate with activated ErbB2 or Ras to enhance tumorigenesis. It does so by regulating the activity of proteins that are essential for gene expression and cell proliferation. Several targets of Pin1 such as c-Myc, the Androgen Receptor, Estrogen Receptor-alpha, Cyclin D1, Cyclin E, p53, RAF kinase and NCOA3 are deregulated in cancer. At the posttranscriptional level, emerging evidence indicates that Pin1 also regulates mRNA decay of histone mRNAs, GM-CSF, Pth, and TGFβ mRNAs by interacting with the histone mRNA specific protein SLBP, and the ARE-binding proteins AUF1 and KSRP, respectively. To understand how Pin1 may affect mRNA abundance on a genome-wide scale in mammalian cells, we used RNAi along with DNA microarrays to identify genes whose abundance is significantly altered in response to a Pin1 knockdown. Functional scoring of differentially expressed genes showed that Pin1 gene targets control cell adhesion, leukocyte migration, the phosphatidylinositol signaling system and DNA replication. Several mRNAs whose abundance was significantly altered by Pin1 knockdown contained AU-rich element (ARE) sequences in their 3' untranslated regions. We identified HuR and AUF1 as Pin1 interacting ARE-binding proteins in vivo. Pin1 was also found to stabilize all core histone mRNAs in this study, thereby validating our results from a previously published study. Statistical analysis suggests that Pin1 may target the decay of essential mRNAs that are inherently unstable and have short to medium half-lives. Thus, this study shows that an important biological role of Pin1 is to regulate mRNA abundance and stability by interacting with specific RNA-binding proteins that may play a role in cancer progression.

Role of prolyl isomerase pin1 in pathogenesis of diseases and remedy for the diseases from natural products

The peptidyl prolyl cis/trans isomerase Pin1, the human ortholog of yeast Ess1 specifically isomerizes peptide bindings of pSer/pThr-Pro residues in various proteins, and regulates the expression levels and functions of phosphorylated proteins. Activation of Pin1 is associated with pathology of a variety of diseases, such as cancer, Alzheimer's disease, infectious diseases and so on. Therefore, regulatory compounds for Pin1 can be applied as a clinical medicine against these diseases. Many chemists have exerted themselves to synthesize the inhibitors based on the 3D structure of Pin1. We have screened for the inhibitors against Pin1 from the natural products including the functional foods. Here we review the Pin1-associated pathology and the known inhibitors identified from natural products. And we introduce the screening methods targeting Pin1 activity.

Prolyl-isomerase Pin1 controls normal and cancer stem cells of the breast

Mammary epithelial stem cells are fundamental to maintain tissue integrity. Cancer stem cells (CSCs) are implicated in both treatment resistance and disease relapse, and the molecular bases of their malignant properties are still poorly understood. Here we show that both normal stem cells and CSCs of the breast are controlled by the prolyl-isomerase Pin1. Mechanistically, following interaction with Pin1, Notch1 and Notch4, key regulators of cell fate, escape from proteasomal degradation by their major ubiquitin-ligase Fbxw7α. Functionally, we show that Fbxw7α acts as an essential negative regulator of breast CSCs' expansion by restraining Notch activity, but the establishment of a Notch/Pin1 active circuitry opposes this effect, thus promoting breast CSCs self-renewal, tumor growth and metastasis in vivo. In human breast cancers, despite Fbxw7α expression, high levels of Pin1 sustain Notch signaling, which correlates with poor prognosis. Suppression of Pin1 holds promise in reverting aggressive phenotypes, through CSC exhaustion as well as recovered drug sensitivity carrying relevant implications for therapy of breast cancers.

[Design, synthesis and biological evaluation of novel diaryl ethers bearing a pyrimidine motif as human Pin1 inhibitors]

Pin1 (peptidyl-prolyl cis-trans isomerase NIMA-interacting 1) belongs to peptidyl-prolyl cis-trans isomerase (PPIase) and is a novel promising anticancer target. Based on the lead structure of benzophenone, a series of novel diarylether derivatives containing a pyrimidine ring were designed and synthesized. The inhibitory activities on Pin1 of compounds 5a-5d and 6a-6i were evaluated by a protease-coupled enzyme assay. Of all the evaluated compounds, 6 compounds displayed inhibitory activities. Molecular docking was performed using FlexX algorithm to explore the binding mode of the active molecules.

Protective effect of nectandrin B, a potent AMPK activator on neointima formation: inhibition of Pin1 expression through AMPK activation

BACKGROUND AND PURPOSE

Neointima is considered a critical event in the development of vascular occlusive disease. Nectandrin B from nutmeg functions as a potent AMP-activated protein kinase (AMPK) activators. The present study addressed whether nectandrin B inhibits intimal hyperplasia in guide wire-injured arteries and examined its molecular mechanism.

EXPERIMENTAL APPROACH

Neointima was induced by guide wire injury in mouse femoral arteries. Cell proliferation and mechanism studies were performed in rat vascular smooth muscle cells (VSMC) culture model.

KEY RESULTS

Nectandrin B increased AMPK activity in VSMC. Nectandrin B inhibited the cell proliferation induced by PDGF and DNA synthesis. Moreover, treatment of nectandrin B suppressed neointima formation in femoral artery after guide wire injury. We have recently shown that Pin1 plays a critical role in VSMC proliferation and neointima formation. Nectandrin B potently blocked PDGF-induced Pin1 and cyclin D1 expression and nectandrin B's anti-proliferation effect was diminished in Pin1 overexpressed VSMC. PDGF-induced phosphorylation of ERK and Akt was marginally affected by nectandrin B. However, nectandrin B increased the levels of p53 and its downstream target p21 and, also reversibly decreased the expression of E2F1 and phosphorylated Rb in PDGF-treated VSMC. AMPK inhibition by dominant mutant form of adenovirus rescued nectandrin B-mediated down-regulation of Pin1 and E2F1.

CONCLUSIONS AND IMPLICATIONS

Nectandrin B inhibited VSMC proliferation and neointima formation via inhibition of E2F1-dependent Pin1 gene transcription, which is mediated through the activation of an AMPK/p53-triggered pathway.

Cyclohexyl ketone inhibitors of Pin1 dock in a trans-diaxial cyclohexane conformation

Cyclohexyl ketone substrate analogue inhibitors (Ac–pSer-Ψ[C = OCH]-Pip–tryptamine) of Pin1, the cell cycle regulatory peptidyl-prolyl isomerase (PPIase), were designed and synthesized as potential electrophilic acceptors for the Pin1 active site Cys113 nucleophile to test a proposed nucleophilic addition-isomerization mechanism. Because they were weak inhibitors, models of all three stereoisomers were docked into the active site of Pin1. Each isomer consistently minimized to a trans-diaxial cyclohexane conformation. From this, we hypothesize that Pin1 stretches substrates into a trans-pyrrolidine conformation to lower the barrier to isomerization. Our reduced amide inhibitor of Pin1 adopted a similar trans-pyrrolidine conformation in the crystal structure. The molecular model of 1, which mimics the l-Ser-l-Pro stereochemistry, in the Pin1 active site showed a distance of 4.4 Å, and an angle of 31° between Cys113-S and the ketone carbon. The computational models suggest that the mechanism of Pin1 PPIase is not likely to proceed through nucleophilic addition.

Inhibition of Plk1 and Pin1 by 5'-nitro-indirubinoxime suppresses human lung cancer cells

A novel indirubin derivative, 5'-nitro-indirubinoxime (5'-NIO), exhibits a strong anti-cancer activity against human cancer cells. Here, the 5'-NIO-mediated G1 cell cycle arrest in lung cancer cells was associated with a decrease in protein levels of polo-like kinase 1 (Plk1) and peptidyl-prolyl cis/trans isomerase Pin1. Treatment with Plk1 siRNA or Pin1 inhibitor effectively inhibited the Rb phosphorylation, suggesting their regulatory role at G1 phase. In addition, the overexpression of Plk1 or Pin1 inhibited apoptotic signals following the cleavage of PARP in 5'-NIO-treated cells. These findings suggest that 5'-NIO have potential anti-cancer efficacy through the inhibition of Plk1 or/and Pin1 expression.

Peptidyl-prolyl isomerase Pin1 is a cellular factor required for hepatitis C virus propagation

The life cycle of hepatitis C virus (HCV) is highly dependent on cellular factors. Using small interfering RNA (siRNA) library screening, we identified peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) as a host factor involved in HCV propagation. Here we demonstrated that silencing of Pin1 expression resulted in decreases in HCV replication in both HCV replicon cells and cell culture-grown HCV (HCVcc)-infected cells, whereas overexpression of Pin1 increased HCV replication. Pin1 interacted with both the NS5A and NS5B proteins. However, Pin1 expression was increased only by the NS5B protein. Both the protein binding and isomerase activities of Pin1 were required for HCV replication. Juglone, a natural inhibitor of Pin1, inhibited HCV propagation by inhibiting the interplay between the Pin1 and HCV NS5A/NS5B proteins. These data indicate that Pin1 modulates HCV propagation and may contribute to HCV-induced liver pathogenesis.

Stereospecific gating of functional motions in Pin1

Pin1 is a modular enzyme that accelerates the cis-trans isomerization of phosphorylated-Ser/Thr-Pro (pS/T-P) motifs found in numerous signaling proteins regulating cell growth and neuronal survival. We have used NMR to investigate the interaction of Pin1 with three related ligands that include a pS-P substrate peptide, and two pS-P substrate analogue inhibitors locked in the cis and trans conformations. Specifically, we compared the ligand binding modes and binding-induced changes in Pin1 side-chain flexibility. The cis and trans binding modes differ, and produce different mobility in Pin1. The cis-locked inhibitor and substrate produced a loss of side-chain flexibility along an internal conduit of conserved hydrophobic residues, connecting the domain interface with the isomerase active site. The trans-locked inhibitor produces a weaker conduit response. Thus, the conduit response is stereoselective. We further show interactions between the peptidyl-prolyl isomerase and Trp-Trp (WW) domains amplify the conduit response, and alter binding properties at the remote peptidyl-prolyl isomerase active site. These results suggest that specific input conformations can gate dynamic changes that support intraprotein communication. Such gating may help control the propagation of chemical signals by Pin1, and other modular signaling proteins.

Death-associated protein kinase 1 phosphorylates Pin1 and inhibits its prolyl isomerase activity and cellular function

Pin1 is a phospho-specific prolyl isomerase that regulates numerous key signaling molecules and whose deregulation contributes to disease notably cancer. However, since prolyl isomerases are often believed to be constitutively active, little is known whether and how Pin1 catalytic activity is regulated. Here, we identify death-associated protein kinase 1 (DAPK1), a known tumor suppressor, as a kinase responsible for phosphorylation of Pin1 on Ser71 in the catalytic active site. Such phosphorylation fully inactivates Pin1 catalytic activity and inhibits its nuclear location. Moreover, DAPK1 inhibits the ability of Pin1 to induce centrosome amplification and cell transformation. Finally, Pin1 pSer71 levels are positively correlated with DAPK1 levels and negatively with centrosome amplification in human breast cancer. Thus, phosphorylation of Pin1 Ser71 by DAPK1 inhibits its catalytic activity and cellular function, providing strong evidence for an essential role of the Pin1 enzymatic activity for its cellular function.

Discovery of cell-active phenyl-imidazole Pin1 inhibitors by structure-guided fragment evolution

Pin1 is an emerging oncology target strongly implicated in Ras and ErbB2-mediated tumourigenesis. Pin1 isomerizes bonds linking phospho-serine/threonine moieties to proline enabling it to play a key role in proline-directed kinase signalling. Here we report a novel series of Pin1 inhibitors based on a phenyl imidazole acid core that contains sub-μM inhibitors. Compounds have been identified that block prostate cancer cell growth under conditions where Pin1 is essential.

Cyclophilin inhibitors for the treatment of HCV infection

Cyclophilins (Cyps) constitute one of the three families of peptidyl prolyl isomerase enzymes. CypA is the prototypical member of the Cyp family and is the predominant Cyp expressed in human cells. Recent studies indicate that CypA has an essential role in supporting HCV-specific RNA replication and protein expression. CypA interacts with several virally expressed proteins, including the non-structural (NS) proteins NS2, NS5A and NS5B, and may regulate diverse activities ranging from polypeptide processing to viral assembly. The introduction of non-immunosuppressive Cyp inhibitors into clinical trials confirms that Cyp inhibition is a valid strategy for developing novel therapeutics for the treatment of chronic HCV infection. This review describes the cyclophilin protein family and the potential roles played by cyclophilins in supporting HCV RNA replication and protein expression, as well as the initial clinical results obtained with a novel series of non-immunosuppressive cyclophilin inhibitors that established the clinical proof of concept for this emerging class of therapeutic agents.

Novel role of Pin1 induction in type II collagen-mediated rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation in joints and subsequent destruction of cartilage and bone. Inflammatory mediators such as PGs and proinflammatory cytokines contribute to RA progress. Pin1, a peptidyl prolyl isomerase, plays important pathophysiological roles in several diseases, including cancer and neurodegeneration. We found that both Pin1 and cyclooxygenase-2 (COX-2) were highly expressed in ankle tissues of type II collagen-induced RA mice. HTB-94 cells overexpressing Pin1 and primary cultured human chondrocytes showed increased basal expression of proinflammatory proteins (COX-2, inducible NO synthase, TNF-alpha, and IL-1beta). Site-directed mutagenesis revealed that Pin1-mediated transcriptional activation of COX-2 was coordinately regulated by NF-kappaB, CREB, and C/EBP. Gel shift, reporter gene, and Western blot analyses confirmed that NF-kappaB, CREB, and C/EBP were consistently activated in chondrocytes overexpressing Pin1. Treatment of RA mice with juglone, a chemical inhibitor of Pin1, significantly reduced RA progress and COX-2 expression in the ankle tissues. Moreover, juglone dose dependently decreased the basal COX-2 expression in primary cultured chondrocytes from RA patients. These results demonstrate that Pin1 induction during RA progress stimulates proinflammatory protein expression by activating NF-kappaB, CREB, and C/EBP, and suggest that Pin1 is a potential therapeutic target of RA.

The peptidyl-prolyl isomerase Pin1 regulates cytokinesis through Cep55

Failure of cytokinesis results in tetraploidy and can increase the genomic instability frequently observed in cancer. The peptidyl-prolyl isomerase Pin1, which is deregulated in many tumors, regulates several processes, including cell cycle progression. Here, we show a novel role for Pin1 in cytokinesis. Pin1 knockout mouse embryonic fibroblasts show a cytokinesis delay, and depletion of Pin1 from HeLa cells also causes a cytokinesis defect. Furthermore, we provide evidence that Pin1 localizes to the midbody ring and regulates the final stages of cytokinesis by binding to centrosome protein 55 kDa (Cep55), an essential component of this ring. This interaction induces Polo-like kinase 1-mediated phosphorylation of Cep55, which is critical for the function of Cep55 during cytokinesis. Importantly, Pin1 knockdown does not enhance the cytokinesis defect in Cep55-depleted cells, indicating that Pin1 and Cep55 act in the same pathway. These data are the first evidence that Pin1 regulates cytokinesis and may provide a mechanistic explanation as to how pathologic levels of Pin1 can stimulate tumorigenesis.

Dipentamethylene thiuram monosulfide is a novel inhibitor of Pin1

Pin1 is involved in eukaryotic cell proliferation by changing the structure and function of phosphorylated proteins. PiB, the Pin1 specific inhibitor, blocks cancer cell proliferation. However, low solubility of PiB in DMSO has limited studies of its effectiveness. We screened for additional Pin1 inhibitors and identified the DMSO-soluble compound dipentamethylene thiuram monosulfide (DTM) that inhibits Pin1 activity with an EC50 value of 4.1 microM. Molecular modeling and enzyme kinetic analysis indicated that DTM competitively inhibits Pin1 activity, with a K(i) value of 0.05 microM. The K(D) value of DTM with Pin1 was determined to be 0.06 microM by SPR technology. Moreover, DTM specifically inhibited peptidyl-prolyl cis/trans isomerase activity in HeLa cells. FACS analysis showed that DTM induced G0 arrest of the HCT116 cells. Our results suggest that DTM has the potential to guide the development of novel antifungal and/or anticancer drugs.

[Recent advance in the study of novel anti-tumor targets and drugs--aurora kinase and Pin1]

Malignant tumor, one of the most refractory diseases, plays a threaten role in human health, the therapy and research on malignant tumor have taken a long way to go. The anti-tumor drugs which are the essential therapy strategies upgrade with the development of new anti-tumor targets and the research on tumor pathogenesis. Aurora kinase and Pin1, the novel anti-tumor targets, maintain the important relationship with tumor. Many new compounds designed on these targets have excellent anti-tumor effects and also enter into phase I or phase II clinical trial.

The prolyl isomerase Pin1 interacts with a ribosomal protein S6 kinase to enhance insulin-induced AP-1 activity and cellular transformation

Phosphorylation of proteins on serine or threonine residues that immediately precede proline (pSer/Thr-Pro) is specifically catalyzed by the peptidyl-prolyl cis-trans isomerase Pin1 and is a central signaling mechanism in cell proliferation and transformation. Although Pin1 is frequently overexpressed in hepatocellular carcinoma (HCC), the molecular mechanism of Pin1 in HCC has not been completely elucidated. Here, we show that Pin1 interacts with p70S6K in vitro and ex vivo. Overexpression of Pin1 resulted in enhanced p70S6K phosphorylation induced by insulin in SK-HEP-1 cells. In contrast, Pin1(-/-) mouse embryonic fibroblasts (MEFs) exhibited significantly decreased insulin-induced p70S6K phosphorylation compared with Pin1(+/+) MEFs. Furthermore, Pin1 enhanced the insulin-induced extracellular signal-regulated protein kinase (ERK)1/2 phosphorylation through its interaction with p70S6K, whereas the inhibition of p70S6K activity by rapamycin suppressed insulin-induced ERK1/2 phosphorylation in SK-HEP-1 cells. Hence, Pin1 affected activator protein-1 activity through p70S6K-ERK1/2 signaling in SK-HEP-1 cells. Most importantly, Pin1-overexpressing JB6 Cl41 cells enhanced neoplastic cell transformation promoted by insulin much more than green fluorescent protein-overexpressing JB6 Cl41 control cells. These results imply that Pin1 amplifies insulin signaling in hepatocarcinoma cells through its interaction with p70S6K, suggesting that Pin1 plays an important role in insulin-induced tumorigenesis and is a potential therapeutic target in hepatocarcinoma.

Pin1-dependent prolyl isomerization modulates the stress-induced phosphorylation of high molecular weight neurofilament protein

Aberrant phosphorylation of neuronal cytoskeletal proteins is a key pathological event in neurodegenerative disorders such as Alzheimer disease (AD) and amyotrophic lateral sclerosis, but the underlying mechanisms are still unclear. Previous studies have shown that Pin1, a peptidylprolyl cis/trans-isomerase, may be actively involved in the regulation of Tau hyperphosphorylation in AD. Here, we show that Pin1 modulates oxidative stress-induced NF-H phosphorylation. In an in vitro kinase assay, the addition of Pin1 substantially increased phosphorylation of NF-H KSP repeats by proline-directed kinases, Erk1/2, Cdk5/p35, and JNK3 in a concentration-dependent manner. In vivo, dominant-negative (DN) Pin1 and Pin1 small interfering RNA inhibited epidermal growth factor-induced NF-H phosphorylation. Because oxidative stress plays an important role in the pathogenesis of neurodegenerative diseases, we studied the role of Pin1 in stressed cortical neurons and HEK293 cells. Both hydrogen peroxide (H(2)O(2)) and heat stresses induce phosphorylation of NF-H in transfected HEK293 cells and primary cortical cultures. Knockdown of Pin1 by transfected Pin1 short interference RNA and DN-Pin1 rescues the effect of stress-induced NF-H phosphorylation. The H(2)O(2) and heat shock induced perikaryal phospho-NF-H accumulations, and neuronal apoptosis was rescued by inhibition of Pin1 in cortical neurons. JNK3, a brain-specific JNK isoform, is activated under oxidative and heat stresses, and inhibition of Pin1 by Pin1 short interference RNA and DN-Pin1 inhibits this pathway. These results implicate Pin1 as a possible modulator of stress-induced NF-H phosphorylation as seen in neurodegenerative disorders like AD and amyotrophic lateral sclerosis. Thus, Pin1 may be a potential therapeutic target for these diseases.

[Recent advances in the study of pin1 and its inhibitors]

Pin1 is a phosphorylation-dependent peptidyl-prolyl cis/trans isomerase, which specifically catalyzes the amide bond isomerization of phosphoserine-proline or phosphothreonine-proline in mitotic phosphoproteins. Pin1 induces the conformational changes to control the function of phosphoproteins. Depletion of Pinl on various human cancer cell lines cause mitotic arrest and apoptosis. Pin1 is an attracting therapeutic target for anticancer and its inhibitors might be potential anticancer drug. In this review, Pin1 inhibitors and the catalytic mechanism, the biological function of Pin1 and its role in oncogenesis are summarized.

Chemical genetics approach to hepatitis C virus replication: cyclophilin as a target for anti-hepatitis C virus strategy

Hepatitis C virus (HCV) is a major causative agent of liver diseases such as chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Because the current standard therapy, interferon (IFN) or pegylated-IFN alone or in combination with ribavirin, is ineffective on approximately half of the HCV-infected patients, alternative therapeutics are greatly needed. The chemical genetics method is a useful strategy to elucidate molecular mechanisms of the viral life cycle and screen for anti-viral agents. This review focuses on the use of chemical genetics approach to virology, which could be called 'chemical virology', and introduces an example of such analysis. From a cell culture-based screening, an immunosuppressant cyclosporin A (CsA) was identified as an anti-HCV compound. Analysis using CsA as a bioprobe showed that cyclophilin (CyP) B, a cellular target of CsA, regulates the function of HCV RNA polymerase NS5B, which is essential for efficient viral genome replication. By targeting CyP, HCV genome replication was drastically suppressed. Thus, chemical genetics analysis identified CyPB as a cellular cofactor of HCV genome replication and a target for novel anti-HCV agents.

Inhibition of Pin1 reduces glutamate-induced perikaryal accumulation of phosphorylated neurofilament-H in neurons

Under normal conditions, the proline-directed serine/threonine residues of neurofilament tail-domain repeats are exclusively phosphorylated in axons. In pathological conditions such as amyotrophic lateral sclerosis (ALS), motor neurons contain abnormal perikaryal accumulations of phosphorylated neurofilament proteins. The precise mechanisms for this compartment-specific phosphorylation of neurofilaments are not completely understood. Although localization of kinases and phosphatases is certainly implicated, another possibility involves Pin1 modulation of phosphorylation of the proline-directed serine/threonine residues. Pin1, a prolyl isomerase, selectively binds to phosphorylated proline-directed serine/threonine residues in target proteins and isomerizes cis isomers to more stable trans configurations. In this study we show that Pin1 associates with phosphorylated neurofilament-H (p-NF-H) in neurons and is colocalized in ALS-affected spinal cord neuronal inclusions. To mimic the pathology of neurodegeneration, we studied glutamate-stressed neurons that displayed increased p-NF-H in perikaryal accumulations that colocalized with Pin1 and led to cell death. Both effects were reduced upon inhibition of Pin1 activity by the use of an inhibitor juglone and down-regulating Pin1 levels through the use of Pin1 small interfering RNA. Thus, isomerization of lys-ser-pro repeat residues that are abundant in NF-H tail domains by Pin1 can regulate NF-H phosphorylation, which suggests that Pin1 inhibition may be an attractive therapeutic target to reduce pathological accumulations of p-NF-H.

The prolyl isomerase Pin1 functions in mitotic chromosome condensation

The prolyl isomerase Pin1 plays important roles in numerous cellular processes. Here we provide evidence that Pin1 has an important function in chromosome condensation during mitosis. We first demonstrate that the interaction of Pin1 with chromatin is greatly elevated in G2/M phase and that this correlates with the presence on chromosomes of several mitotic phosphoproteins, especially topoisomerase (Topo) IIalpha. Inducible overexpression of Pin1 was shown to result in higher M phase-specific phosphorylation, while downregulation of Pin1 by siRNA treatment reduced phosphorylation of TopoIIalpha and other mitotic proteins. Furthermore, immunodepletion of Pin1 from mitotic cell extracts prevented such extracts from inducing chromosome condensation when added to S phase nuclei. Indeed, purified Pin1 and cdc2/cyclin B kinase were by themselves sufficient to induce condensation. This reflects the ability of Pin1 to increase TopoIIalpha phosphorylation by cdc2/cyclin B in vitro, which in turn dramatically increased formation of a TopoIIalpha/Pin1/DNA complex.

Characterization of hepatitis C virus subgenomic replicon resistance to cyclosporine in vitro

Treatment of hepatitis C virus (HCV) infection has been met with less than satisfactory results due primarily to its resistance to and significant side effects from alpha interferon (IFN-alpha). New classes of safe and broadly acting treatments are urgently needed. Cyclosporine (CsA), an immunosuppressive and anti-inflammatory drug for organ transplant patients, has recently been shown to be highly effective in suppressing HCV replication through a mechanism that is distinct from the IFN pathway. Here we report the selection and characterization of HCV replicon cells that are resistant to CsA treatment in vitro, taking advantage of our ability to sort live cells that are actively replicating HCV RNA in the presence of drug treatments. This resistance is specific to CsA as the replicon cells most resistant to CsA were still sensitive to IFN-alpha and a polymerase inhibitor. We demonstrate that the resistant phenotype is not a result of general enhanced replication and, furthermore, that mutations in the coding region of HCV NS5B contribute to the resistance. Interestingly, a point mutation (I432V) isolated from the most resistant replicon was able to rescue a lethal mutation (P540A) in NS5B that disrupts its interaction with its cofactor, cyclophilin B (CypB), even though the I432V mutation is located outside of the reported CypB binding site (amino acids 520 to 591). Our results demonstrate that CsA exerts selective pressure on the HCV genome, leading to the emergence of resistance-conferring mutations in the viral genome despite acting upon a cellular protein.

Structure-based identification of small molecule compounds targeting cell cyclophilin A with anti-HIV-1 activity

Cyclophilin A acts as protein folding chaperones and intracellular transports in many cellular processes. Previous studies have shown that cyclophilin A can interact with HIV-1 (human immunodeficiency virus type 1) gag protein and enhance viral infectivity. Many cyclophilin A inhibitors such as cyclosporin A can inhibit HIV-1 replication in vitro. Here, we report a structure-based identification of novel non-peptidic cyclophilin A inhibitors as anti-HIV lead compounds. Following a computer-aided virtual screening and subsequent surface plasmon resonance (SPR) analysis, 12 low molecular weight cyclophilin A ligands were selected for further evaluation of their in vitro inhibition of peptidyl-prolyl cis-trans isomerase (PPIase) activity of cyclophilin A and HIV-1 replication. Five of these compounds (FD5, FD8, FD9, FD10 and FD12) exhibited inhibition against both PPIase activity and HIV-1 infection. These active compounds will be used as leads for structure and activity relationship (SAR) and optimization studies in order to design more effective anti-HIV-1 therapeutics, and as probes for investigating the effect of cyclophilins on HIV-1 replication.

Structural basis for high-affinity peptide inhibition of human Pin1

Human Pin1 is a key regulator of cell-cycle progression and plays growth-promoting roles in human cancers. High-affinity inhibitors of Pin1 may provide a unique opportunity for disrupting oncogenic pathways. Here we report two high-resolution X-ray crystal structures of human Pin1 bound to non-natural peptide inhibitors. The structures of the bound high-affinity peptides identify a type-I beta-turn conformation for Pin1 prolyl peptide isomerase domain-peptide binding and an extensive molecular interface for high-affinity recognition. Moreover, these structures suggest chemical elements that may further improve the affinity and pharmacological properties of future peptide-based Pin inhibitors. Finally, an intramolecular hydrogen bond observed in both peptide complexes mimics the cyclic conformation of FK506 and rapamycin. Both FK506 and rapamycin are clinically important inhibitors of other peptidyl-prolyl cis-trans isomerases. This comparative discovery suggests that a cyclic peptide polyketide bridge, like that found in FK506 and rapamycin or a similar linkage, may significantly improve the binding affinity of structure-based Pin1 inhibitors.

Benefits from the use of a pimecrolimus-based treatment in the management of atopic dermatitis in clinical practice. Analysis of a Swiss cohort

BACKGROUND

Controlled studies established the efficacy and good tolerability of pimecrolimus cream 1% for the treatment of atopic dermatitis but they may not reflect real-life use.

OBJECTIVE

To evaluate the efficacy, tolerability and cosmetic acceptance of a pimecrolimus-based regimen in daily practice in Switzerland.

METHODS

This was a 6-month, open-label, multicentre study in 109 patients (55% > or = 18 years) with atopic dermatitis. Pimecrolimus cream 1% was incorporated into patients' standard treatment protocols.

RESULTS

The pimecrolimus-based treatment was well tolerated and produced disease improvement in 65.7% of patients. It was particularly effective on the face (improvement rate: 75.0%). Mean pimecrolimus consumption decreased from 6.4 g/day (months 1-3) to 4.0 g/day (months 3-6) as disease improved. Most patients (74.1%) rated their disease control as 'complete' or 'good' and 90% were highly satisfied with the cream formulation.

CONCLUSION

The use of a pimecrolimus-based regimen in everyday practice was effective, well tolerated and well accepted by patients.

Interaction of the transmembrane domain of lysis protein E from bacteriophage phiX174 with bacterial translocase MraY and peptidyl-prolyl isomerase SlyD

The molecular target for the bacteriolytic E protein from bacteriophage X174, responsible for host cell lysis, is known to be the enzyme phospho-MurNAc-pentapeptide translocase (MraY), an integral membrane protein involved in bacterial cell wall peptidoglycan biosynthesis, with an essential role being played by peptidyl-prolyl isomerase SlyD. A synthetic 37 aa peptide E(pep), containing the N-terminal transmembrane alpha-helix of E, was found to be bacteriolytic against Bacillus licheniformis, and inhibited membrane-bound MraY. The solution conformation of E(pep) was found by circular dichroism (CD) spectroscopy to be 100 % alpha-helical. No change in the CD spectrum was observed upon addition of purified Escherichia coli SlyD, implying that SlyD does not catalyse prolyl isomerization upon E. However, E(pep) was found to be a potent inhibitor of SlyD-catalysed peptidyl-prolyl isomerization (IC(50) 0.15 microM), implying a strong interaction between E and SlyD. E(pep) was found to inhibit E. coli MraY activity when assayed in membranes (IC(50) 0.8 microM); however, no inhibition of solubilized MraY was observed, unlike nucleoside natural product inhibitor tunicamycin. These results imply that the interaction of E with MraY is not at the MraY active site, and suggest that a protein-protein interaction is formed between E and MraY at a site within the transmembrane region.

Improvement in pruritus in children with atopic dermatitis using pimecrolimus cream 1%

The objective of this study was to assess time to onset of pruritus improvement in a pediatric population treated with pimecrolimus cream 1%. This 8-day, double-blinded, vehicle-controlled study randomized 174 children and adolescents (aged 2-17 years) with mild to moderate atopic dermatitis (AD) and moderate to severe pruritus to twice-daily applications of pimecrolimus cream 1% or vehicle. There were no significant between-group differences in demographics or baseline disease characteristics. Pruritus was assessed by subjects using a 4-point pruritus severity scale (0-3). The primary efficacy variable was time to a 1 point or more improvement in pruritus score from baseline. The 2 treatment groups were compared using log-rank testing of the time-to-event data. In the per-protocol (PP) population, median times to a 1 point or more improvement in pruritus score were 48 and 72 hours for pimecrolimus and vehicle groups, respectively (P = .038). From day 3 onward, significantly more subjects (P = .023) in the pimecrolimus group versus the vehicle group reported complete pruritus resolution. Pimecrolimus cream 1% improved pruritus within 48 hours in children and adolescents with mild to moderate AD and achieved complete resolution of pruritus in a significantly greater number of subjects in the pimecrolimus group versus the vehicle group by the end of the 7-day treatment period (P = .008).

1% pimecrolimus, 0.005% calcipotriol, and 0.1% betamethasone in the treatment of intertriginous psoriasis: a double-blind, randomized controlled study

OBJECTIVE

During the last decades, management of intertriginous psoriasis (IP) has been unsatisfactory because of the adverse effects associated with long-term corticosteroid application and the lack of alternatives. Recently, both pimecrolimus and tacrolimus have been investigated for this indication and shown to be safe and effective. So far, to our knowledge, a comparison of one of these drugs with standard regimens for IP has not been performed.

DESIGN

A single-center, 4-week, double-blind, randomized, vehicle-controlled comparison study to assess the safety and efficacy of 1% pimecrolimus, 0.005% calcipotriol, and 0.1% betamethasone valerate in the treatment of IP.

SETTING

Dermatologic hospital at Ruhr University of Bochum.

PATIENTS

Eighty adults with IP.

INTERVENTIONS

Treatment of IP with 1% pimecrolimus, 0.005% calcipotriol, 0.1% betamethasone, or the vehicle once daily for 28 days.

MAIN OUTCOME MEASURES

Mean reduction of the Modified Psoriasis Area and Severity Index (M-PASI) score after 28 days of treatment was considered the primary outcome measure, which was analyzed on an intention-to-treat basis. The secondary outcome was a visual analog scale score for itching.

RESULTS

After 4 weeks of treatment, the 3 active compounds and the vehicle resulted in a significant decrease in mean M-PASI score (86.4% for 0.1% betamethasone, 62.4% for 0.005% calcipotriol, 39.7% for 1% pimecrolimus, and 21.1% for vehicle). The 0.1% betamethasone was significantly more effective than 1% pimecrolimus during the study period (P<.05). No significant difference was found between 0.005% calcipotriol and 0.1% betamethasone and between 0.005% calcipotriol and 1% pimecrolimus. The visual analog scale score for pruritus decreased by 78% for 0.1% betamethasone, 57% for 0.005% calcipotriol, 35% for 1% pimecrolimus, and 43% for the vehicle, again demonstrating a clear advantage for the corticosteroid (P<.05).

CONCLUSIONS

The 1% pimecrolimus was shown to be less potent than 0.1% betamethasone in the treatment of IP. Considering the adverse-effect profile of long-term application of corticosteroids, occasional or intermittent rescue therapy with short-term topical corticosteroids and maintenance with a less potent agent, such as 1% pimecrolimus or 0.005% calcipotriol, might be appropriate for patients with IP in general practice.

Pin1 contributes to cervical tumorigenesis by regulating cyclin D1 expression

The prolyl isomerase Pin1, which specifically catalyzes conformational changes in certain proline-directed phosphorylation sites, is thought to be a critical catalyst for multiple oncogenic pathways. However, little is known about the role of Pin1 in human cervical cancer. Our previous study showed that Pin1 was overexpressed in cervical cancer tissues as well as cell lines. In this study, whether Pin1 is involved in cervical oncogenesis by regulating cyclin D1 was explored and the potential of Pin1-targeted gene silencing in inhibiting cellular growth and tumorigenicity in cervical cancer was investigated. A Pin1-directed shRNA and a sense Pin1 plasmid were constructed, and then the effects of the shRNA and the sense plasmid on HeLa cells were evaluated. The results showed that Pin1 directly regulated cyclin D1 levels. In addition, silencing Pin1 with RNAi significantly reduced cancer cell proliferation, colony formation, and strongly enhanced the apoptosis of HeLa cells. It is suggested that Pin1 may contribute to cervical tumorigenesis by regulating cyclin D1 expression and Pin1 may serve as a promising molecular target for diagnostics and therapeutics in cervical cancer.