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Objective The UPrEPU mobile app is a self-monitoring system to enable men who have sex with men to optimize their pre-exposure prophylaxis adherence for HIV prevention. The app was designed to accommodate a rather complicated event-driven dosing schedule. We aim to evaluate the usability of the UPrEPU app and its effectiveness in improving adherence monitoring. Methods From May to October 2020, 35 participants were enrolled for the usability study and followed up for 4 months. Blood samples for the drug concentration in the dried blood spots were obtained once during the second to fourth follow-up visits. The effectiveness of adherence monitoring was analyzed using Cohen's kappa statistic to calculate the concordance between the average number of pills taken and drug concentration in the dried blood spots. Results Overall retention was 91.4% (32 participants) at the end of the study. Participants used the app for a mean of 29 days and made 2565 data entries in total, with an average of 76 data entries. The average systematic usability scale score for the app was 71.5, indicating acceptable usability. Slight agreement was reached between the dried blood spots measurement and the number of pills taken and recorded in the app (weighted kappa: 0.21). Conclusions Our user-centered UPrEPU app demonstrated that it could accommodate both daily and event-driven dosing schedules for men who have sex with men clients with acceptable usability scores. We confirmed that complex behaviors such as different drug-dosing regimens that are contingent on sexual behaviors could be incorporated into the design of a mobile app.

BACKGROUND New innovative technologies, such as mobile apps, have been developed to increase pre-exposure prophylaxis (PrEP) adherence and the use of log sex diaries. The contiguity of mobile apps reduces the recall bias that generally affects reported condom and PrEP use. However, none of the currently used mobile apps were designed for event-driven PrEP users, and few studies have demonstrated the potential usage of sex diary data to facilitate the understanding of the different HIV risks among heterogeneous profiles of sex diaries and PrEP use. OBJECTIVE We aim to discriminate the heterogeneous profiles of sex events and PrEP use and examine the risk of condomless anal sex among different types of sex events. METHODS We recruited 35 adult men who have sex with men from two medical centers in Taiwan since May 2020 and followed up for four months. Participants were on PrEP or willing to take PrEP. They were asked to log their sex events, PrEP use, and dosing regimens on a mobile app to improve their PrEP adherence. Latent class analysis was used to distinguish profiles of sex events and PrEP use. Indicators included correct intake of PrEP for each sex event, participants’ sexual positioning, partner’s HIV status, and age. RESULTS A total of 551 sex events were classified into three classes by latent class analysis: PrEP nonadherent flip-flopping (234/551, 42%), PrEP imperfect-adherent power bottoming (284/551, 52%), and PrEP adherent serodiscordant topping (33/551, 6%). “PrEP nonadherent flip-flopping” sex events were more likely to involve condomless anal sex than “PrEP imperfect-adherent power bottoming” (OR 1.83, 95% CI 1.03-3.25) after considering random intercepts for individuals, and this class needed to increase their PrEP adherence and use of condoms. “PrEP imperfect-adherent power bottoming” realized their own risk and packaged PrEP with condoms to protect themselves. Up to 99% (32/33) of sex events in “PrEP adherent serodiscordant topping” were protected by PrEP, but all of the sex events in this group were condomless. CONCLUSIONS Using the sex diary data could advance the capacity to identify high-risk groups. HIV prevention strategy should be more flexible and combine PrEP with condom use for future HIV prevention.

Background: The dense fibrotic stroma enveloping pancreatic tumors is a major cause of drug resistance. Pancreatic stellate cells (PSCs) in the stroma can be activated to induce intra-tumor fibrosis and worsen patient survival; however, the molecular basics for the regulation of PSC activation remains unclear. Methods: The in vitro coculture system was used to study cancer cell-PSC interactions. Atomic force microscopy was used to measure the stiffness of tumor tissues and coculture gels. Cytokine arrays, qPCR, and Western blotting were performed to identify the potential factors involved in PSC activation and to elucidate underlying pathways. Results: PSC activation characterized by α-SMA expression was associated with increased pancreatic tumor stiffness and poor prognosis. Coculture with cancer cells induced PSC activation, which increased organotypic coculture gel stiffness and cancer cell invasion. Cancer cells-derived PAI-1 identified from coculture medium could activate PSCs, consistent with pancreatic cancer tissue microarray analysis showing a strong positive correlation between PAI-1 and α-SMA expression. Suppression by knocking down PAI-1 in cancer cells demonstrated the requirement of PAI-1 for coculture-induced PSC activation and gel stiffness. PAI-1 could be upregulated by KRAS in pancreatic cancer cells through ERK. In PSCs, inhibition of LRP-1, ERK, and c-JUN neutralized the effect of PAI-1, suggesting the contribution of LRP-1/ERK/c-JUN signaling. Furthermore, activated PSCs might exacerbate malignant behavior of cancer cells via IL-8 because suppression of IL-8 signaling reduced pancreatic tumor growth and fibrosis in vivo. Conclusions: KRAS-mutant pancreatic cancer cells can activate PSCs through PAI-1/LRP-1 signaling to promote fibrosis and cancer progression.

Background Daily and on-demand pre-exposure prophylaxis (PrEP) has been well demonstrated to effectively prevent HIV acquisition for men who have sex with men (MSM). More than half of the MSM PrEP users in Taiwan prefer on-demand PrEP; however, on-demand PrEP involves a complicated dosing regimen because it requires precoital and postcoital dosing and sex events are hard to anticipate. Although there are a growing number of mobile apps designed to improve access to HIV prevention services and HIV medication adherence, few mobile apps focus on adherence to PrEP or are designed to accommodate a complicated, on-demand PrEP dosing schedule. Objective The aim of this project is to evaluate the usability of a newly developed mobile app (UPrEPU) to assist MSM PrEP users to self-monitor their adherence to either daily or on-demand PrEP using a user-centered scheme. Methods This research will be conducted in 2 phases: app development and usability study. In the app development phase, we will first conduct formative research with end users and stakeholders through in-depth interviews; the results will provide PrEP users’ and PrEP navigators’ personas as material used in the app conceptualization stage. PrEP navigators are individuals in the health care system that help HIV-negative individuals who need assistance in accessing PrEP care. A low-fidelity prototype of the app feature will be formatted by applying a participatory design approach to engage PrEP users, designers, and app developers in the design process of the app. Then, a high-fidelity prototype of the app will be developed for the usability study and refined iteratively by the multidisciplinary team and new internal testers. Internal testers include the research team consisting of experts in public health, infectious disease, and industrial design and a close network of the research team that is taking PrEP. In the usability study phase, we will enroll 70 MSM PrEP users and follow them up for 4 months. Usability, feasibility, and effectiveness of adherence monitoring will be evaluated. Results Refinement of the UPrEPU app is currently ongoing. The usability study commenced in May 2020. Conclusions The UPrEPU app is one of the first apps designed to help MSM PrEP users to self-manage their PrEP schedule better regardless of dosing modes. With a design-thinking approach and adapting to the cultural context in Taiwan’s MSM population, this novel app will have substantial potential to be acceptable and feasible and contribute to the reduction of new HIV infections. Trial Registration ClinicalTrials.gov NCT04248790; https://clinicaltrials.gov/ct2/show/NCT04248790 International Registered Report Identifier (IRRID) PRR1-10.2196/20360

Background Cancer subtype switching, which involves unclear cancer cell origin, cell fate decision, and transdifferentiation of cells within a confined tumor microenvironment, remains a major problem in pancreatic cancer (PDA). Results By analyzing PDA subtypes in The Cancer Genome Atlas, we identified that epigenetic silencing of apoptosis-associated tyrosine kinase (AATK) inversely was correlated with mRNA expression and was enriched in the quasi-mesenchymal cancer subtype. By comparing early mouse pancreatic lesions, the non-invasive regions showed AATK co-expression in cells with acinar-to-ductal metaplasia, nuclear VAV1 localization, and cell cycle suppression; but the invasive lesions conversely revealed diminished AATK expression in those with poorly differentiated histology, cytosolic VAV1 localization, and co-expression of p63 and HNF1α. Transiently activated AATK initiates acinar differentiation into a ductal cell fate to establish apical-basal polarization in acinar-to-ductal metaplasia. Silenced AATK and ectopically expressed p63 and HNF1α allow the proliferation of ductal PanINs in mice. Conclusion Epigenetic silencing of AATK regulates the cellular transdifferentiation, proliferation, and cell cycle progression in converting PDA-subtypes.

BACKGROUND Daily and on-demand pre-exposure prophylaxis (PrEP) has been well demonstrated to effectively prevent HIV acquisition for men who have sex with men (MSM). More than half of the MSM PrEP users in Taiwan prefer on-demand PrEP; however, on-demand PrEP involves a complicated dosing regimen because it requires precoital and postcoital dosing and sex events are hard to anticipate. Although there are a growing number of mobile apps designed to improve access to HIV prevention services and HIV medication adherence, few mobile apps focus on adherence to PrEP or are designed to accommodate a complicated, on-demand PrEP dosing schedule. OBJECTIVE The aim of this project is to evaluate the usability of a newly developed mobile app (UPrEPU) to assist MSM PrEP users to self-monitor their adherence to either daily or on-demand PrEP using a user-centered scheme. METHODS This research will be conducted in 2 phases: app development and usability study. In the app development phase, we will first conduct formative research with end users and stakeholders through in-depth interviews; the results will provide PrEP users’ and PrEP navigators’ personas as material used in the app conceptualization stage. PrEP navigators are individuals in the health care system that help HIV-negative individuals who need assistance in accessing PrEP care. A low-fidelity prototype of the app feature will be formatted by applying a participatory design approach to engage PrEP users, designers, and app developers in the design process of the app. Then, a high-fidelity prototype of the app will be developed for the usability study and refined iteratively by the multidisciplinary team and new internal testers. Internal testers include the research team consisting of experts in public health, infectious disease, and industrial design and a close network of the research team that is taking PrEP. In the usability study phase, we will enroll 70 MSM PrEP users and follow them up for 4 months. Usability, feasibility, and effectiveness of adherence monitoring will be evaluated. RESULTS Refinement of the UPrEPU app is currently ongoing. The usability study commenced in May 2020. CONCLUSIONS The UPrEPU app is one of the first apps designed to help MSM PrEP users to self-manage their PrEP schedule better regardless of dosing modes. With a design-thinking approach and adapting to the cultural context in Taiwan’s MSM population, this novel app will have substantial potential to be acceptable and feasible and contribute to the reduction of new HIV infections. CLINICALTRIAL ClinicalTrials.gov NCT04248790; https://clinicaltrials.gov/ct2/show/NCT04248790 INTERNATIONAL REGISTERED REPORT PRR1-10.2196/20360

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The highly homeostasis-resistant nature of cancer cells leads to their escape from treatment and to liver metastasis, which in turn makes pancreatic ductal adenocarcinoma (PDAC) difficult to treat, especially the squamous/epithelial-to-mesenchymal transition (EMT)-like subtype. As the molecular mechanisms underlying tumour heterogeneity remain elusive, we investigated whether epigenetic regulation might explain inter-individual differences in the progression of specific subtypes. DNA methylation profiling performed on cancer tissues prior to chemo/radiotherapy identified one hypermethylated CpG site (CpG6882469) in the VAV1 gene body that was correlated with demethylation of two promoter CpGs (CpG6772370/CpG6772811) in both PDAC and peripheral blood. Transforming growth factor β treatment induced gene-body hypermethylation, dissociation of DNMT1 from the promoter, and VAV1 expression via SMAD4 and mutant KrasG12D. Pharmacological inhibition of TGFβ-VAV1 signalling decreased the squamous/EMT-like cancer cells, promoted nuclear VAV1 localization, and enhanced the efficacy of gemcitabine in prolonging the survival of KPfl/flC mice. Together, the three VAV1 CpGs serve as biomarkers for prognosis and early detection, and the TGFβ-VAV1 axis represents a therapeutic target.

The proposed resistance-locked loop (RLL) can achieve high PSRR of $-$ 16 dB digital low dropout (DLDO) regulator without consuming much power which is the drawback in prior arts. Even at light loads, the RLL can be shut down for power saving. Furthermore, the duty compensator ensures DLDO stability under different duty ratio of supply voltage. The operation voltage of proposed DLDO can be down to 0.6 V and the peak current efficiency is 99.99%. The test chip was fabricated in 40 nm CMOS process with all the transistors implemented by core device for small silicon area.

SummaryEarly-onset prostate cancer (EO-PCA) represents the earliest clinical manifestation of prostate cancer. To compare the genomic alteration landscapes of EO-PCA with “classical” (elderly-onset) PCA, we performed deep sequencing-based genomics analyses in 11 tumors diagnosed at young age, and pursued comparative assessments with seven elderly-onset PCA genomes. Remarkable age-related differences in structural rearrangement (SR) formation became evident, suggesting distinct disease pathomechanisms. Whereas EO-PCAs harbored a prevalence of balanced SRs, with a specific abundance of androgen-regulated ETS gene fusions including TMPRSS2:ERG, elderly-onset PCAs displayed primarily non-androgen-associated SRs. Data from a validation cohort of > 10,000 patients showed age-dependent androgen receptor levels and a prevalence of SRs affecting androgen-regulated genes, further substantiating the activity of a characteristic “androgen-type” pathomechanism in EO-PCA.

Model comparison is one useful approach in applications of structural equation modeling. Akaike’s information criterion (AIC) and the Bayesian information criterion (BIC) are commonly used for selecting an optimal model from the alternatives. We conducted a comprehensive evaluation of various model selection criteria, including AIC, BIC, and their extensions, in selecting an optimal path model under a wide range of conditions over different compositions of candidate set, distinct values of misspecified parameters, and diverse sample sizes. The chance of selecting an optimal model rose as the values of misspecified parameters and sample sizes increased. The relative performance of AIC and BIC type criteria depended on the magnitudes of the parameter misspecified. The BIC family in general outperformed AIC counterparts unless under small values of omitted parameters and sample sizes, where AIC performed better. Scaled unit information prior BIC (SPBIC) and Haughton's BIC (HBIC) demonstrated the highest accuracy ratios across most of the conditions investigated in this simulation.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer death in the United States. This study was aimed at evaluating the efficacy of AR-42 (formerly OSU-HDAC42), a novel histone deacetylase (HDAC) inhibitor currently in clinical trials, in suppressing tumor growth and/or cancer-induced muscle wasting in murine models of PDAC. EXPERIMENTAL DESIGN: The in vitro antiproliferative activity of AR-42 was evaluated in six human pancreatic cancer cell lines (AsPC-1, COLO-357, PANC-1, MiaPaCa-2, BxPC-3, SW1990). AsPC-1 subcutaneous xenograft and transgenic KP fl/fl C (LSL-Kras G12D ;Trp53 flox/flox ;Pdx-1-Cre) mouse models of pancreatic cancer were used to evaluate the in vivo efficacy of AR-42 in suppressing tumor growth and/or muscle wasting. RESULTS: Growth suppression in AR-42–treated cells was observed in all six human pancreatic cancer cell lines with dose-dependent modulation of proliferation and apoptotic markers, which was associated with the hallmark features of HDAC inhibition, including p21 upregulation and histone H3 hyperacetylation. Oral administration of AR-42 at 50 mg/kg every other day resulted in suppression of tumor burden in the AsPC-1 xenograft and KP fl/fl C models by 78% and 55%, respectively, at the end of treatment. Tumor suppression was associated with HDAC inhibition, increased apoptosis, and inhibition of proliferation. Additionally, AR-42 as a single agent preserved muscle size and increased grip strength in KP fl/fl C mice. Finally, the combination of AR-42 and gemcitabine in transgenic mice demonstrated a significant increase in survival than either agent alone. CONCLUSIONS: These results suggest that AR-42 represents a therapeutically promising strategy for the treatment of pancreatic cancer.

A series of 1-arylsulfonyl-5-(N-hydroxyacrylamide)indoles has been identified as a new class of histone deacetylase inhibitors. Compounds 8, 11, 12, 13, and 14 demonstrated stronger antiproliferative activities than 1 (SAHA) with GI(50) values ranging from 0.36 to 1.21 μM against Hep3B, MDA-MB-231, PC-3, and A549 human cancer cell lines. Lead compound 8 showed remarkable HDAC 1, 2, and 6 isoenzymes inhibitory activities with IC(50) values of 12.3, 4.0, 1.0 nM, respectively, which are comparable to 1. In in vivo efficacy evaluation against lung A549 xenograft model, 8 displayed better antitumor activity than compound 1.

Details of the evolution of strategies toward convergent assembly of the histone deacetylase inhibiting natural product largazole exploiting γ,δ-unsaturated-α,β-epoxy-aldehydes and a thiazole-thiazoline containing ω-amino-acid are described. The initial N-heterocyclic carbene mediated redox amidation exploying these two types of building blocks representing largazole's structural domains of distinct biosynthetic origin directly afforded the seco-acid of largazole. This was accomplished without any protecting groups resident upon either thioester bearing epoxy-aldehyde or the tetrapeptide. However, the ineffective production of largazole via the final macrolactonization led to an alternative intramolecular esterification/macrolactamization strategy employing the established two building blocks. This provided largazole along with its C2-epimer via an unexpected inversion of the α-stereocenter at the valine residue. The biological evaluation demonstrated that both largazole and 2-epi-largazole led to dose-dependent increases of acetylation of histone H3, indicating their potencies as class I histone deacetylase selective inhibitiors. Enhanced p21 expression was also induced by largazole and its C2 epimer. In addition, 2-epi-largazole displayed more potent activity than largazole in cell viability assays against PC-3 and LNCaP prostate cancer cell lines.

This study investigates the mechanism by which histone deacetylase (HDAC) inhibitors up-regulate histone H3 lysine 4 (H3K4) methylation. Exposure of LNCaP prostate cancer cells and the prostate tissue of transgenic adenocarcinoma of the mouse prostate mice to the pan- and class I HDAC inhibitors (S)-(+)-N-hydroxy-4-(3-methyl-2-phenyl-butyrylamino)-benzamide (AR42), N-(2-aminophenyl)-4-[N-(pyridine-3-yl-methoxycarbonyl)-aminomethyl]-benzamide (MS-275), and vorinostat led to differential increases in H3K4 methylation. Chromatin immunoprecipitation shows that this accumulation of methylated H3K4 occurred in conjunction with decreases in the amount of the H3K4 demethylase RBP2 at the promoter of genes associated with tumor suppression and differentiation, including KLF4 and E-cadherin. This finding, together with the HDAC inhibitor-induced up-regulation of KLF4 and E-cadherin, suggests that HDAC inhibitors could activate the expression of these genes through changes in histone methylation status. Evidence indicates that this up-regulation of H3K4 methylation was attributable to the suppressive effect of these HDAC inhibitors on the expression of RBP2 and other JARID1 family histone demethylases, including PLU-1, SMCX, and LSD1, via the down-regulation of Sp1 expression. Moreover, shRNA-mediated silencing of the class I HDAC isozymes 1, 2, 3, and 8, but not that of the class II isozyme HDAC6, mimicked the drug effects on H3K4 methylation and H3K4 demethylases, which could be reversed by ectopic Sp1 expression. These data suggest a cross-talk mechanism between HDACs and H3K4 demethylases via Sp1-mediated transcriptional regulation, which underlies the complexity of the functional role of HDACs in the regulation of histone modifications.

This study is aimed at the pharmacological exploitation of alpha-tocopheryl succinate (1) to develop potent antiadhesion agents. Considering the structural cooperativity between the phytyl chain and the carboxylic terminus in determining the antiadhesion activity, our structural optimization led to compound 5 ([2-(4,8-dimethyl-non-1-enyl)-2,5,7,8-tetramethyl-chroman-6-yloxy]-acetic acid), which exhibited an-order-of-magnitude higher potency than 1 in blocking the adhesion of 4T1 metastatic breast cancer cells to extracellular matrix proteins (IC(50), 0.6 microM versus 10 microM). Evidence indicates that the ability of compound 5 to block cell adhesion and migration was attributable to its effect on disrupting focal adhesion and actin cytoskeletal integrity by facilitating the degradation of focal adhesion kinase. Interactions between tumor cells and the ECM in the tumor microenvironment have been increasingly recognized as critical modulators of the metastatic potential of tumor cells. Consequently, the ability of compound 5 to block such interactions provides a unique pharmacological tool to shed light onto mechanisms that govern cell adhesion and tumor metastasis.

As part of our effort to understand the mechanism underlying alpha-tocopheryl succinate [vitamin E succinate (VES)]-mediated antitumor effects, we investigated the signaling pathway by which VES suppresses androgen receptor (AR) expression in prostate cancer cells. VES and, to a greater extent, its truncated derivative TS-1 mediated transcriptional repression of AR in prostate cancer cells but not in normal prostate epithelial cells; a finding that underscores the differential susceptibility of normal versus malignant cells to the antiproliferative effect of these agents. This AR repression was attributable to the ability of VES and TS-1 to facilitate the proteasomal degradation of the transcription factor Sp1. This mechanistic link was corroborated by the finding that proteasome inhibitors or ectopic expression of Sp1 protected cells against drug-induced AR ablation. Furthermore, evidence suggests that the destabilization of Sp1 by VES and TS-1 resulted from the inactivation of Jun N-terminal kinases (JNKs) as a consequence of increased phosphatase activity of protein phosphatase 2A (PP2A). Stable transfection of LNCaP cells with the dominant-negative JNK1 plasmid mimicked drug-induced Sp1 repression, whereas constitutive activation of JNK kinase activity or inhibition of PP2A activity by okadaic acid protected Sp1 from VES- and TS-1-induced degradation. From a mechanistic perspective, the ability of VES and TS-1 to activate PP2A activity underscores their broad spectrum of effects on multiple signaling mechanisms, including those mediated by Akt, mitogen-activated protein kinases, nuclear factor kappaB, Sp1 and AR. This pleiotropic effect in conjunction with low toxicity suggests the translational potential for developing TS-1 into potent PP2A-activating agents for cancer therapy.

A procedure for estimating the reliability of test scores in the context of ecological momentary assessment (EMA) was proposed to take into account the characteristics of EMA measures. Two commonly used test scores in EMA were considered: the aggregated score (AGGS) and the within-person centered score (WPCS). Conceptually, AGGS and WPCS represent the interindividual differences and the intraindividual differences, respectively. The reliability coefficients for AGGS and WPCS were derived using a multilevel factor model with a serial correlation structure framework. Point estimates and confidence intervals of these coefficients were obtained using Mx ( Neale, Boker, Xie, & Maes, 2004 ). A simulation study showed that the proposed procedure performed well empirically. Diary data from Huang (2009) , which recorded daily joy level of 110 undergraduate students for 8 days, was used to illustrate the applicability of the proposed method.

MUC1-C overexpression has been associated with the progression of pancreatic tumors by promoting the aggressive and metastatic phenotypes. As MUC1 is a STAT3 target gene, STAT3 plays a major role in regulating MUC1-C expression. In this study, we report an alternative mechanism by which integrin-linked kinase (ILK) post-transcriptionally modulates the expression of MUC1-C by maintaining its protein stability in pancreatic cancer cells. We found that ILK acts in concert with STAT3 to facilitate IL-6-mediated upregulation of MUC1-C; ILK depletion was equally effective as STAT3 depletion in abolishing IL-6-induced MUC1-C overexpression without disturbing the phosphorylation or cellular distribution of STAT3. Conversely, ectopic expression of constitutively active ILK increased MUC1-C expression, though this increase was not noted with kinase-dead ILK. This finding suggests the requirement of the kinase activity of ILK in regulating MUC1-C stability, which was confirmed by using the ILK kinase inhibitor T315. Furthermore, our data suggest the involvement of protein kinase C (PKC)δ in mediating the suppressive effect of ILK inhibition on MUC1-C repression. For example, co-immunoprecipitation analysis indicated that ILK depletion-mediated MUC1-C phosphorylation was accompanied by increased phosphorylation of PKCδ at the activation loop Thr-507 and increased binding of PKCδ to MUC1-C. Conversely, ILK overexpression resulted in decreased PKCδ phosphorylation. From a mechanistic perspective, the present finding, together with our recent report that ILK controls the expression of oncogenic KRAS through a regulatory loop, underscores the pivotal role of ILK in promoting pancreatic cancer progression.

Vitamin E is a fat-soluble vitamin that includes isomers of tocopherols and tocotrienols which are known for their antioxidant properties. Tocopherols are the predominant form encountered in the diet and through supplementation, and have garnered interest for their potential cancer therapeutic and chemopreventive effects, which include the dephosphorylation of Akt, a serine/threonine kinase that plays a pivotal role in important cellular processes, such as cell growth, survival, metabolism and motility. Full catalytic activation of Akt requires phosphorylation at both Thr308 and Ser473. Dephosphorylation of Ser473 drastically reduces Akt catalytic activity and the number of downstream substrates it can regulate. The mechanism by which α- and γ-tocopherol facilitate the selective dephosphorylation of the kinase Akt at Ser473 was investigated. We showed that this site-specific Akt dephosphorylation was mediated through the pleckstrin homology (PH) domain-dependent recruitment to the plasma membrane of Akt and PHLPP1 (PH domain leucine-rich repeat protein phosphatase, isoform 1), a phosphatase that dephosphorylates Akt at Ser473. The ability of α- and γ-tocopherol to induce PHLPP-mediated Akt inhibition established PHLPP as a “druggable” target. We structurally optimized these tocopherols to obtain derivatives with greater in vitro potency and in vivo tumor-suppressive activity in two prostate xenograft tumor models. Binding affinities for the PH domains of Akt and PHLPP1 were greater than for other PH domain-containing proteins, which may underlie the preferential membrane recruitment of these proteins. Molecular modeling revealed the structural determinants of the interaction with the PH domain of Akt that may inform strategies for continued structural optimization. These findings describe a mechanism by which tocopherols facilitate the dephosphorylation of Akt at Ser473, thereby providing insights into the mode of antitumor action of tocopherols and a rationale for the translational development of tocopherols into novel PH domain-targeted Akt inhibitors.

A recent study reports that histone deacetylase (HDAC) inhibitors, AR42 and MS- 275, upregulated H3K4 methylation marks in prostate cancer cells, leading to transcriptional activation of genes including those associated with roles in tumor suppression and cell differentiation (1). Evidence suggests that the crosstalk between histone deacetylation and histone H3K4 methylation is attributable to the ability of these HDAC inhibitors to repress the JARID1 family of histone H3 lysine 4 demethylases (H3K4DMs), including RBP2, PLU-1, SMCX, and LSD1, through the downregulation of Sp1 expression. This demonstrates the complexity of the functional roles of HDACs in the regulation of histone modifications as well as the activation of epigenetically silenced gene expression. Equally important is the ability of HDAC inhibitors to transcriptionally suppress H3K4DM gene expression which has therapeutic implications, in that several H3K4DMs such as LSD1 and PLU-1 have been implicated in the pathogenesis of many types of malignancies.

Although energy restriction has been recognized as an important target for cancer prevention, the mechanism by which energy restriction-mimetic agents (ERMAs) mediate apoptosis remains unclear. By using a novel thiazolidinedione-derived ERMA, CG-12 (Wei, S., Kulp, S. K., and Chen, C. S. (2010) J. Biol. Chem. 285, 9780–9791), vis-a-vis 2-deoxyglucose and glucose deprivation, we obtain evidence that epigenetic activation of the tumor suppressor gene Kruppel-like factor 6 (KLF6) plays a role in ERMA-induced apoptosis in LNCaP prostate cancer cells. KLF6 regulates the expression of many proapoptotic genes, and shRNA-mediated KLF6 knockdown abrogated the ability of ERMAs to induce apoptosis. Chromatin immunoprecipitation analysis indicates that this KLF6 transcriptional activation was associated with increased histone H3 acetylation and histone H3 lysine 4 trimethylation occupancy at the promoter region. Several lines of evidence demonstrate that the enhancing effect of ERMAs on these active histone marks was mediated through transcriptional repression of histone deacetylases and H3 lysine 4 demethylases by down-regulating Sp1 expression. First, putative Sp1-binding elements are present in the promoters of the affected histone-modifying enzymes, and luciferase reporter assays indicate that site-directed mutagenesis of these Sp1 binding sites significantly diminished the promoter activities. Second, shRNA-mediated knockdown of Sp1 mimicked the repressive effect of energy restriction on these histone-modifying enzymes. Third, ectopic Sp1 expression protected cells from the repressive effect of CG-12 on these histone-modifying enzymes, thereby abolishing the activation of KLF6 expression. Together, these findings underscore the intricate relationship between energy restriction and epigenetic regulation of tumor suppressor gene expression, which has therapeutic relevance to foster novel strategies for prostate cancer therapy.

Nasopharyngeal carcinoma (NPC) is one of the most common malignancies in the head and neck region, especially among those of Chinese origin. NPC has multifactorial aetiologies including genetic susceptibility, consumption of food with high salt content, and the Epstein–Barr virus. The primary tumour usually arises from the lateral walls of the nasopharynx and is characterized by a rich sub-mucosal lymphatic structure, often leading to cervical lymph node metastasis. Distant metastasis has been recognized to be a major cause of treatment failure in patients with nasopharyngeal carcinoma. Bone, liver and lung are the most frequent sites of NPC metastases.

This study reports a histone deacetylation-independent mechanism whereby histone deacetylase (HDAC) inhibitors sensitize prostate cancer cells to DNA-damaging agents by targeting Ku70 acetylation. Ku70 represents a crucial component of the nonhomologous end joining repair machinery for DNA double-strand breaks (DSB). Our data indicate that pretreatment of prostate cancer cells with HDAC inhibitors (trichostatin A, suberoylanilide hydroxamic acid, MS-275, and OSU-HDAC42) led to increased Ku70 acetylation accompanied by reduced DNA-binding affinity without disrupting the Ku70/Ku80 heterodimer formation. As evidenced by increased Ser139-phosphorylated histone H2AX (γH2AX), impaired Ku70 function diminished cellular capability to repair DNA DSBs induced by bleomycin, doxorubicin, and etoposide, thereby enhancing their cell-killing effect. This sensitizing effect was most prominent when cells were treated with HDAC inhibitors and DNA-damaging agents sequentially. Mimicking acetylation was done by replacing K282, K317, K331, K338, K539, or K542 with glutamine via site-directed mutagenesis, which combined with computer docking analysis was used to analyze the role of these lysine residues in the interactions of Ku70 with DNA broken ends. Mutagenesis of K282, K338, K539, or K542 suppressed the activity of Ku70 to bind DNA, whereas mutagenesis of K317 or K331 with glutamine had no significant effect. Moreover, overexpression of K282Q or K338Q rendered DU-145 cells more susceptible to the effect of DNA-damaging agents on γH2AX formation and cell killing. Overall, the ability of HDAC inhibitors to regulate cellular ability to repair DNA damage by targeting Ku70 acetylation underlies the viability of their combination with DNA-damaging agents as a therapeutic strategy for prostate cancer. [Cancer Res 2007;67(11):5318–27]