Stearic acid attenuates profibrotic signalling in idiopathic pulmonary fibrosis.

BACKGROUND AND OBJECTIVE: Lipid metabolism dysregulation has been implicated in the pathogenesis of IPF; however, the roles of most lipid metabolites in lung fibrosis remain unexplored. Therefore, we aimed to identify changes in lipid metabolites in the lung tissues of IPF patients and determine their roles in pulmonary fibrosis. METHODS: Free fatty acids in the lung tissues of IPF patients and controls were quantified using a metabolomic approach. The roles of free fatty acids in fibroblasts or epithelial cells treated with TGF-ß1 were evaluated using fibrotic markers. The antifibrotic role of stearic acid was also assessed in a bleomycin-induced lung fibrosis mouse model. Protein levels in cell lysates or tissues were measured by western blotting. RESULTS: The levels of stearic acid were lower in IPF lung tissues than in control lung tissues. Stearic acid significantly reduced TGF-ß1-induced α-SMA and collagen type 1 expression in MRC-5 cells. Furthermore, stearic acid decreased the levels of p-Smad2/3 and ROS in MRC-5 cells treated with TGF-ß1 and disrupted TGF-ß1-induced EMT in Beas-2B cells. Stearic acid reduced the levels of bleomycin-induced hydroxyproline in a mouse model. CONCLUSION: Changes in the free fatty acid profile, including low levels of stearic acid, were observed in IPF patients. Stearic acid may exert antifibrotic activity by regulating profibrotic signalling.

Correction to: A novel histone deacetylase inhibitor, CG200745, potentiates anticancer effect of docetaxel in prostate cancer via decreasing Mcl-1 and Bcl-XL.

The blots of control and docetaxel for caspase-9, caspase-3, caspase-8, Bcl-XL, and tubulin in the Figure 4f were reused from Figure 4 of our previous paper published in Journal of Urology in 2010 ( https://doi.org/10.1016/j.juro.2010.07.035 ).

Combination treatment with docetaxel and histone deacetylase inhibitors downregulates androgen receptor signaling in castration-resistant prostate cancer.

Backgrounds Since most patients with castration-resistant prostate cancer (CRPC) develop resistance to its standard therapy docetaxel, many studies have attempted to identify novel combination treatment to meet the large clinical unmet need. In this study, we examined whether histone deacetylase inhibitors (HDACIs) enhanced the effect of docetaxel on AR signaling in CRPC cells harboring AR and its splice variants. Methods HDACIs (vorinostat and CG200745) were tested for their ability to enhance the effects of docetaxel on cell viability and inhibition of AR signaling in CRPC 22Rv1 and VCaP cells by using CellTiter-Glo™ Luminescent cell viability assay, synergy index analysis and Western blotting. The nuclear localization of AR was examined via immunocytochemical staining in 22Rv1 cells and primary tumor cells from a patient with CRPC. Results Combination treatment with HDACIs (vorinostat or CG200745) and docetaxel synergistically inhibited the growth of 22Rv1 and VCaP cells. Consistently, the combination treatment decreased the levels of full-length AR (AR-FL), AR splice variants (AR-Vs), prostate-specific antigen (PSA), and anti-apoptotic Bcl-2 proteins more efficiently compared with docetaxel or vorinostat alone. Moreover, the combination treatment accelerated the acetylation and bundling of tubulin, which significantly inhibited the nuclear accumulation of AR in 22Rv1 cells. The cytoplasmic colocalization of AR-FL and AR-V7 with microtubule bundles increased after combination treatment in primary tumor cells from a patient with CRPC. Conclusions The results suggested that docetaxel, in combination with HDACIs, suppressed the expression and nuclear translocation of AR-FL and AR-Vs and showed synergistic anti-proliferative effect in CRPC cells. This combination therapy may be useful for the treatment of patients with CRPC.

Chebulinic acid attenuates glutamate-induced HT22 cell death by inhibiting oxidative stress, calcium influx and MAPKs phosphorylation.

Glutamate-induced excitotoxicity and oxidative stress is a major causative factor in neuronal cell death in acute brain injuries and chronic neurodegenerative diseases. The prevention of oxidative stress is a potential therapeutic strategy. Therefore, in the present study, we aimed to examine a potential therapeutic agent and its protective mechanism against glutamate-mediated cell death. We first found that chebulinic acid isolated from extracts of the fruit of Terminalia chebula prevented glutamate-induced HT22 cell death. Chebulinic acid significantly reduced intracellular reactive oxygen species (ROS) production and Ca2+ influx induced by glutamate. We further demonstrated that chebulinic acid significantly decreased the phosphorylation of mitogen-activated protein kinases (MAPKs), including ERK1/2, JNK, and p38, as well as inhibiting pro-apoptotic Bax and increasing anti-apoptotic Bcl-2 protein expression. Moreover, we demonstrated that chebulinic acid significantly reduced the apoptosis induced by glutamate in HT22 cells. In conclusion, our results in this study suggest that chebulinic acid is a potent protectant against glutamate-induced neuronal cell death via inhibiting ROS production, Ca2+ influx, and phosphorylation of MAPKs, as well as reducing the ratio of Bax to Bcl-2, which contribute to oxidative stress-mediated neuronal cell death.

Downregulation of androgen receptors by NaAsO2 via inhibition of AKT-NF-κB and HSP90 in castration resistant prostate cancer.

BACKGROUND: Androgen and androgen receptor (AR) play essential roles in the development and maintenance of prostate cancer. The recently identified AR splice variants (AR-Vs) have been considered as a plausible mechanism for the primary resistance against androgen deprivation therapy (ADT) in castration-resistant prostate cancer (CRPC). Sodium meta-arsenite (NaAsO2 ; KML001; Kominox), a trivalent arsenical, is an orally bioavailable and water soluble, which is currently in phase I/II clinical trials for the treatment of prostate cancer. It has a potent anti-cancer effect on prostate cancer cells and xenografts. The aim of this study was to examine the effect of NaAsO2 on AR signaling in LNCaP and 22Rv1 CRPC cells. METHODS: We used hormone-sensitive LNCaP cells, hormone-insensitive 22Rv1 cells, and CRPC patient-derived primary cells. We analyzed anti-cancer effect of NaAsO2 using real-time quantitative reverse transcription-PCR, Western blotting, immunofluorescence staining and CellTiter Glo® luminescent assay. Statistical evaluation of the results was performed by one-way ANOVA. RESULTS: NaAsO2 significantly reduced the translocation of AR and AR-Vs to the nucleus as well as their level in LNCaP and 22Rv1 cells. Besides, the level of the prostate-specific antigen (PSA), downstream target gene of AR, was also decreased. This compound was also an effective modulator of AKT-dependent NF-κB activation which regulates AR. NaAsO2 significantly inhibited phosphorylation of AKT and expression and nuclear translocation of NF-κB. We then investigated the effect of NaAsO2 on AR stabilization. NaAsO2 promoted HSP90 acetylation by down-regulating HDAC6, which reduces the stability of AR in prostate cancer cells. CONCLUSIONS: Here, we show that NaAsO2 disrupts AR signaling at multiple levels by affecting AR expression, stability, and degradation in primary tumor cell cultures from prostate cancer patients as well as CRPC cell lines. These results suggest that NaAsO2 could be a novel therapeutics for prostate cancer.

Down-regulation of mortalin exacerbates Aß-mediated mitochondrial fragmentation and dysfunction.

Mitochondrial dynamics greatly influence the biogenesis and morphology of mitochondria. Mitochondria are particularly important in neurons, which have a high demand for energy. Therefore, mitochondrial dysfunction is strongly associated with neurodegenerative diseases. Until now various post-translational modifications for mitochondrial dynamic proteins and several regulatory proteins have explained complex mitochondrial dynamics. However, the precise mechanism that coordinates these complex processes remains unclear. To further understand the regulatory machinery of mitochondrial dynamics, we screened a mitochondrial siRNA library and identified mortalin as a potential regulatory protein. Both genetic and chemical inhibition of mortalin strongly induced mitochondrial fragmentation and synergistically increased Aß-mediated cytotoxicity as well as mitochondrial dysfunction. Importantly we determined that the expression of mortalin in Alzheimer disease (AD) patients and in the triple transgenic-AD mouse model was considerably decreased. In contrast, overexpression of mortalin significantly suppressed Aß-mediated mitochondrial fragmentation and cell death. Taken together, our results suggest that down-regulation of mortalin may potentiate Aß-mediated mitochondrial fragmentation and dysfunction in AD.

Indomethacin preconditioning induces ischemic tolerance by modifying zinc availability in the brain.

Intracellular zinc overload causes neuronal injury during the course of neurological disorders, whereas mild levels of zinc are beneficial to neurons. Previous reports indicated that non-steroidal anti-inflammatory drugs, including indomethacin and aspirin, can reduce the risk of ischemic stroke. This study found that chronic pretreatment of rats with indomethacin, a non-selective cyclooxygenase inhibitor, provided tolerance to ischemic injuries in an animal model of stroke by eliciting moderate zinc elevation in neurons. Consecutive intraperitoneal injection of indomethacin (3mg/kg/day for 28 days) led to modest increases in intraneuronal zinc as well as synaptic zinc content, with no significant stimulation of neuronal death. Furthermore, indomethacin induced the expressions of intracellular zinc homeostatic and neuroprotective proteins, rendering the brain resistant against ischemic damages and improving neurological outcomes. However, administration of a zinc-chelator, N,N,N',N'-tetra(2-picolyl)ethylenediamine (TPEN; 15 mg/kg/day), immediately after indomethacin administration eliminated the beneficial actions of the drug. Therefore, indomethacin preconditioning can modulate intracellular zinc availability, contributing to ischemic tolerance in the brain after stroke.

Synergistic anticancer efficacy of MEK inhibition and dual PI3K/mTOR inhibition in castration-resistant prostate cancer.

BACKGROUND: PTEN deletion, mutation or reduced expression occurs in 63% of metastatic prostate tumors, resulting in the activation of PI3K and its downstream targets, AKT and mTOR. Inhibition of the PI3K pathway results in upregulation of the MAPK pathway. Therefore, co-administration of inhibitors of both pathways, GSK2126458 as a dual PI3K/mTOR inhibitor, and AZD6244 as a MEK inhibitor, is able to overcome resistance and increase anti-tumor efficacy. METHODS: PC3, DU145, LNCaP, and CRPC patient-derived cells were used to assess apoptosis upon exposure to the drug combination. The human DU145 and PC3 tumor xenograft mouse model was employed to evaluate in vivo efficacy. CellTiter Glo® luminescent assay, annexin V-FITC apoptosis detection, cell cycle analysis, Western blotting and immunohistochemistry were conducted. Statistical evaluation of the results was performed by one-way ANOVA. RESULTS: The combination of GSK2126458 and AZD6244 inhibited the growth of DU145 and PC3 prostate cancer cells in vitro and in vivo. GSK2126458 decreased phospho-AKT while increasing phospho-ERK and AZD6244 decreased phospho-ERK efficiently while increasing phospho-AKT. The combination of GSK2126458 and AZD6244 decreased both phospho-AKT and phospho-ERK effectively in vitro and in vivo. The combination treatment synergistically induced annexin V-positive cells, sub-G1 cells, and cleavage of caspase-9, caspase-3 and poly-ADP ribose polymerase (PARP) in DU145 cells in vitro. Moreover, the combination decreased the level of Ki-67, and increased TUNEL-positive cells and cleaved caspase-3 in DU145 xenograft tumors implanted in mice. In addition, this combination treatment inhibited both the PI3K and MEK pathway primary in cultures from CRPC patients harboring PTEN loss, leading to synergistic anti-tumor effect. CONCLUSIONS: The combination of GSK2126458 and AZD6244 blocks both the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways simultaneously and is an effective strategy for the treatment of CRPCs.

BIX-01294-induced autophagy regulates elongation of primary cilia.

Previously, we showed that BIX-01294 treatment strongly activates autophagy. Although, the interplay between autophagy and ciliogenesis has been suggested, the role of autophagy in ciliogenesis is controversial and largely unknown. In this study, we investigated the effects of autophagy induced by BIX-01294 on the formation of primary cilia in human retinal pigmented epithelial (RPE) cells. Treatment of RPE cells with BIX-01294 caused strong elongation of the primary cilium and increased the number of ciliated cells, as well as autophagy activation. The elongated cilia in serum starved cultured cells were gradually decreased by re-feeding the cells with normal growth medium. However, the disassembly of cilia was blocked in the BIX-01294-treated cells. In addition, both genetic and chemical inhibition of autophagy suppressed BIX-01294-mediated ciliogenesis in RPE cells. Taken together, these results suggest that autophagy induced by BIX-01294 positively regulates the elongation of primary cilium.

Combination treatment of renal cell carcinoma with belinostat and 5-fluorouracil: a role for oxidative stress induced DNA damage and HSP90 regulated thymidine synthase.

PURPOSE: Despite several therapeutic options renal cell carcinoma is associated with a poor clinical outcome. Therefore, we investigated whether combining 5-fluorouracil with the histone deacetylase inhibitor belinostat would exert a synergistic effect on renal cell carcinoma cells in vitro and in vivo. MATERIALS AND METHODS: We used SN12C cells treated with 5-fluorouracil and/or belinostat in vitro and in xenograft experiments in vivo. Cell viability and death mechanisms were assessed by MTS assay and Western blot. To investigate the role of reactive oxygen species we used H2DCF-DA, reactive oxygen species scavengers and the roGFP2 construct. RESULTS: Belinostat potentiated the anticancer effect of 5-fluorouracil. It synergistically induced apoptosis by activating caspases and increasing the subG1 cell population. Effects on reactive oxygen species mediated DNA damage included decreased thioredoxin expression and increased levels of TBP-2, γ-H2AX and Ac-H3. Furthermore, belinostat attenuated the 5-fluorouracil mediated induction of thymidylate synthase via HSP90 hyperacetylation. Co-administration of 5-fluorouracil with belinostat similarly reduced tumor volume and weight, and increased γ-H2AX and Ac-H3 levels in the SN12C xenograft model. CONCLUSIONS: In combination with 5-fluorouracil the targeted inhibitor of histone deacetylase synergistically inhibited renal cancer cell growth by the blockade of thymidylate synthase induction and the induction of reactive oxygen species mediated DNA damage in vitro and in vivo. Our results suggest that combined treatment with belinostat and 5-fluorouracil may represent a promising new approach to renal cancer.

Novel peptides functionally targeting in vivo human lung cancer discovered by in vivo peptide displayed phage screening.

Discovery of the cancer-specific peptidic ligands have been emphasized for active targeting drug delivery system and non-invasive imaging. For the discovery of useful and applicable peptidic ligands, in vivo peptide-displayed phage screening has been performed in this study using a xenograft mouse model as a mimic microenvironment to tumor. To seek human lung cancer-specific peptides, M13 phage library displaying 2.9 × 10(9) random peptides was intravenously injected into mouse model bearing A549-derived xenograft tumor through the tail vein. Then the phages emerged from a course of four rounds of biopanning in the xenograft tumor tissue. Novel peptides were categorized into four groups according to a sequence-homology phylogenicity, and in vivo tumor-targeting capacity of these peptides was validated by whole body imaging with Cy5.5-labeled phages in various cancer types. The result revealed that novel peptides accumulated only in adenocarcinoma lung cancer cell-derived xenograft tissue. For further confirmation of the specific targeting ability, in vitro cell-binding assay and immunohistochemistry in vivo tumor tissue were performed with a selected peptide. The peptide was found to bind intensely to lung cancer cells both in vitro and in vivo, which was efficiently compromised with unlabeled phages in an in vitro competition assay. In conclusion, the peptides specifically targeting human lung cancer were discovered in this study, which is warranted to provide substantive feasibilities for drug delivery and imaging in terms of a novel targeted therapeutics and diagnostics.

Usefulness of optical coherence tomography to detect central serous chorioretinopathy in monkeys.

Many systemic drugs can induce ocular toxicity and several ocular side-effects have been identified in clinical studies. However, it is difficult to detect ocular toxicity in preclinical studies because of the lack of appropriate evaluation methods. Optical coherence tomography (OCT) is useful because it can provide real-time images throughout a study period, whereas histopathology only provides images of sacrificed animals. Using OCT alongside histopathology, attempts were made to find effective approaches for screening of drug-induced ocular toxicity in monkeys. Such approaches could be used in preclinical studies prior to human trials. Six male cynomolgus monkeys (Macaca fascicularis Raffles) were orally administered one of six candidate MAPK/ERK kinase (MEK) inhibitors. Central serous chorioretinopathy, a known side-effect of such inhibitors, was identified in four monkeys by OCT. Artifacts generated during tissue processing meant that histopathology could not detect edematous changes. Thus, OCT is a useful tool to detect ocular toxicity which cannot be detected by histopathology in preclinical studies.

Sodium meta-arsenite induces reactive oxygen species-dependent apoptosis, necrosis, and autophagy in both androgen-sensitive and androgen-insensitive prostate cancer cells.

Sodium meta-arsenite (NaAsO2), a novel compound synthesized by Komipham International Co. Ltd, is an orally bioavailable, water-soluble trivalent arsenical that has shown potent cytotoxic activity in human solid cancer cells in vitro and in vivo, and is currently undergoing phase I/II clinical trials for the treatment of prostate cancer. In this study, mechanisms of cell death induced by sodium meta-arsenite were investigated. Sodium meta-arsenite reduced cell viability and increased the sub-G1 population in cell cycle analysis in both androgen-sensitive LNCaP and androgen-insensitive CWR22RV1 cells. The apoptosis induced by sodium meta-arsenite was associated with cleavage of caspases 3, 8, and 9, and poly (ADP-ribose) polymerase (PARP) and increased annexin V-positive cells, and was inhibited by the pan-caspase inhibitor Z-VAD-fmk. Sodium meta-arsenite also increased the level of the autophagy marker microtubule-associated protein 1 light chain 3 (LC3)-II and the number of autophagic vacuoles as shown by electron microscopy. Both the autophagy inhibitor 3-methyladenine and the necrosis inhibitor necrostatin-1 blocked cell death induced by sodium meta-arsenite. Moreover, sodium meta-arsenite led to the accumulation of intracellular reactive oxygen species (ROS) and N-acetyl-L-cysteine (NAC), a ROS scavenger, decreased sodium meta-arsenite-induced levels of cleaved PARP and LC3-II. Propidium iodide (PI) staining also showed that NAC restored membrane integrity, damaged by sodium meta-arsenite. Therefore, these results suggest that sodium meta-arsenite induces apoptotic, necrotic, and autophagic cell death through intracellular ROS accumulation in both androgen-sensitive and androgen-insensitive prostate cancer cells and may be used as a new anticancer drug for the treatment of prostate cancer.

Dual inhibition of MEK1/2 and EGFR synergistically induces caspase-3-dependent apoptosis in EGFR inhibitor-resistant lung cancer cells via BIM upregulation.

Epidermal growth factor receptor (EGFR) gene mutations activate the KRAS-RAF-MEK-ERK pathway in lung cancer cells. EGFR tyrosine kinase inhibitors (TKIs) such as gefitinib induce apoptosis of cancer cells, but prolonged treatment is often associated with acquired resistance. Here, we identified a novel MEK1/2 inhibitor, CZ0775, and compared its cytotoxic effects to those of AZD6244 (selumetinib) in non-small cell lung cancer (NSCLC) cell lines harboring EGFR mutations. The lapatinib-sensitive HCC827 and PC9 and lapatinib-resistant H1650 and H1975 cell lines showed poor responses to CZ0775 and AZD6244 monotherapy with an IC50 > 10 µM. By contrast, combination treatment with lapatinib and CZ0775 inhibited cell proliferation and produced a 2-fold higher number of annexin V-labeled cells than lapatinib alone in H1975 cells. Furthermore, combination treatment decreased phosphorylated extracellular signal related kinase (p-ERK) and survivin levels and upregulated the expression of the pro-apoptotic protein BIM. siRNA-mediated BIM depletion reduced caspase-3 activity (~40%) in lapatinib and CZ0775 treated H1975 cells. An in vitro ERK activity assay showed that p-ERK levels were approximately a 3-fold lower in H1975 cells treated with CZ0775 and lapatinib combination than in cells treated with lapatinib alone. CZ0775 was more cytotoxic than AZD6244 when used in combination with lapatinib. Our results suggest that combination treatment with CZ0774 and EGFR inhibitors is a promising therapeutic approach for the treatment of EGFR-TKI-resistant lung cancers and its effect is mediated by the inhibition of ERK and the induction of BIM.

A novel biguanide derivative, IM176, induces prostate cancer cell death by modulating the AMPK-mTOR and androgen receptor signaling pathways.

Background: Metformin and phenformin, biguanide derivatives that are widely used to treat type 2 diabetes mellitus, have recently been shown to exert potential anticancer effects in prostate cancer. This study compared the antiprostate cancer effects of the novel biguanide derivative IM176 with those of metformin and phenformin. Methods: Prostate cancer cell lines and patient-derived castration-resistant prostate cancer (CRPC) cells were treated with IMI76, metformin, and phenformin. The effects of these agents on cell viability, annexin V-FITC apoptosis, mammalian target of rapamycin inhibition, protein expression and phosphorylation, and gene expression were evaluated. Results: IM176 dose dependently reduced the viability of all prostate cancer cell lines tested, with IC50s (LNCaP: 18.5 µM; 22Rv1: 36.8 µM) lower than those of metformin and phenformin. IM176 activated AMP-activated protein kinase, inhibiting mammalian target of rapamycin and reducing the phosphorylation of p70S6K1 and S6. IM176 inhibited the expression of androgen receptor, the androgen receptor splice variant 7, and prostate-specific antigen in LNCaP and 22Rv1 cells. IM176 increased caspase-3 cleavage and annexin V-positive/propidium iodide-positive cells, which indicated apoptosis. Moreover, IM176 reduced viability, with low IC50, in cultured cells derived from two patients with CRPC. Conclusion: The antitumor effects of IM176 were comparable with those of other biguanides. IM176 may therefore be a novel candidate for the treatment of patients with prostate cancer, including those with CRPC.

Carnitine sensitizes TRAIL-resistant cancer cells to TRAIL-induced apoptotic cell death through the up-regulation of Bax.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor family with apoptosis-inducing activity. Given that TRAIL selectively induces cell death in various tumors but has little or no toxicity to normal cells, TRAIL agonists have been considered as promising anti-cancer therapeutic agents. However, the resistance of many primary tumors and cancer cells to TRAIL poses a challenge. In our present study, we found that carnitine, a metabolite that transfers long-chain fatty acids into mitochondria for beta-oxidation and modulates protein kinase C activity, sensitizes TRAIL-resistant cancer cells to TRAIL. Combination of carnitine and TRAIL was found to synergistically induce apoptotic cell death through caspase activation, which was blocked by a pan caspase inhibitor, but not by an inhibitor of autophagy or an inhibitor of necrosis. The combination of carnitine and TRAIL reversed the resistance to TRAIL in lung cancer cells, colon carcinoma cells, and breast carcinoma cells. We further demonstrate that carnitine, either alone or in combination with TRAIL, enhances the expression of the pro-apoptotic Bcl-2 family protein, Bcl-2-associated X protein (Bax). The down-regulation of Bax expression by small interfering RNA reduced caspase activation when cells were treated with TRAIL, and experiments with cells from Bax knockout mice confirmed this result. Taken together, our current results suggest that carnitine can reverse the resistance of cancer cells to TRAIL by up-regulating Bax expression. Thus, a combined delivery of carnitine and TRAIL may represent a new therapeutic strategy to treat TRAIL-resistant cancer cells.

A novel histone deacetylase inhibitor, CG200745, potentiates anticancer effect of docetaxel in prostate cancer via decreasing Mcl-1 and Bcl-XL.

We synthesized a novel hydroxamate-based pan-histone deacetylase inhibitor (HDACI), CG200745 {(E)-2-(Naphthalen-1-yloxymethyl)-oct-2-enedioic acid 1-[(3-dimethylamino-propyl)-amide] 8-hydroxyamide]}. Like other inhibitors, for example vorinostat and belinostat, CG200745 has the hydroxamic acid moiety to bind zinc at the bottom of catalytic pocket. Firstly, we analyzed its inhibitory activity against histone deacetylase (HDAC) in hormone-dependent LNCaP cells and hormone-independent DU145 and PC3 cells. CG200745 inhibited deacetylation of histone H3 and tubulin as much as vorinostat and belinostat did. CG200745 also inhibited growth of prostate cancer cells, increased sub-G1 population, and activated caspase-9, -3 and -8 in LNCaP, DU145 and PC3 cells. These results indicate that CG200745 induces apoptosis. Next, we examined the effect of CG200745 on cell death induced by docetaxel in DU145 cells in vitro and in vivo. Compared to mono-treatment with each drug, pre-treatment of DU145 cells with docetaxel followed by CG200745 showed synergistic cytotoxicity, and increased the apoptotic sub-G1 population, caspase activation, and tubulin acetylation. Moreover, the combination treatment decreased Mcl-1 and Bcl-(XL). Docetaxel and CG200745 combination reduced tumor size in the DU145 xenograft model. These preclinical results show that combination treatment with docetaxel and new HDACI, CG200745, potentiated anti-tumor effect in hormone-refractory prostate cancer (HRPC) cells via activation of apoptosis.

Protective Role of miR-34c in Hypoxia by Activating Autophagy through BCL2 Repression.

Hypoxia leads to significant cellular stress that has diverse pathological consequences such as cardiovascular diseases and cancers. MicroRNAs (miRNAs) are one of regulators of the adaptive pathway in hypoxia. We identified a hypoxia-induced miRNA, miR-34c, that was significantly upregulated in hypoxic human umbilical cord vein endothelial cells (HUVECs) and in murine blood vessels on day 3 of hindlimb ischemia (HLI). miR-34c directly inhibited BCL2 expression, acting as a toggle switch between apoptosis and autophagy in vitro and in vivo. BCL2 repression by miR-34c activated autophagy, which was evaluated by the expression of LC3-II. Overexpression of miR-34c inhibited apoptosis in HUVEC as well as in a murine model of HLI, and increased cell viability in HUVEC. Importantly, the number of viable cells in the blood vessels following HLI was increased by miR-34c overexpression. Collectively, our findings show that miR-34c plays a protective role in hypoxia, suggesting a novel therapeutic target for hypoxic and ischemic diseases in the blood vessels.

Zinc enhances autophagic flux and lysosomal function through transcription factor EB activation and V-ATPase assembly.

The stimulation of autophagy or lysosomes has been considered therapeutic for neurodegenerative disorders because the accumulation of misfolded proteins is commonly observed in the brains of individuals with these diseases. Although zinc is known to play critical roles in the functions of lysosomes and autophagy, the mechanism behind this regulatory relationship remains unclear. Therefore, in this study, we examined which mechanism is involved in zinc-mediated activation of autophagy and lysosome. Exposure to zinc at a sub-lethal concentration activated autophagy in a concentration-dependent manner in mRFP-GFP-LC3-expressing H4 glioma cells. Zinc also rescued the blocking of autophagic flux arrested by pharmaceutical de-acidification. Co-treatment with zinc attenuated the chloroquine (CQ)-induced increase in the number and size of mRFP-GFP-LC3 puncta in H4 cells and accumulation of p62 by CQ or ammonium chloride in both H4 and mouse cerebrocortical cultures. Zinc rapidly induced the expression of cathepsin B (CTSB) and cathepsin D (CTSD), representative lysosomal proteases in neurons, which appeared likely to be mediated by transcription factor EB (TFEB). We observed the translocation of TFEB from neurite to nucleus and the dephosphorylation of TFEB by zinc. The addition of cycloheximide, a chemical inhibitor of protein synthesis, inhibited the activity of CTSB and CTSD at 8 h after zinc exposure but not at 1 h, indicating that only late lysosomal activation was dependent on the synthesis of CTSB and CTSD proteins. At the very early time point, the activation of cathepsins was mediated by an increased assembly of V-ATPase on lysosomes and resultant lysosomal acidification. Finally, considering that P301L mutation in tau protein causes frontotemporal dementia through aggressive tau accumulation, we investigated whether zinc reduces the accumulation of protein aggregates in SK-N-BE(2)-C neuroblastoma cells expressing wild-type tau or mutant P301L-tau. Zinc markedly attenuated the levels of phosphorylated tau and total tau as well as p62 in both wild-type and mutant tau-overexpressing cells. We also observed that zinc was more effective than rapamycin at inducing TFEB-dependent CTSB and CTSD expression and V-ATPase-dependent lysosomal acidification and CTSB/CTSD activation. These results suggest that the regulation of zinc homeostasis could be a new approach for developing treatments for neurodegenerative diseases, including Alzheimer's and Parkinson's.

miR-96-5p targets PTEN to mediate sunitinib resistance in clear cell renal cell carcinoma.

A multiple receptor tyrosine kinase inhibitor, sunitinib, is a first-line therapy for clear cell renal cell carcinoma (CCRCC). Unfortunately, it has the major challenges of low initial response rate and resistance after about one year of treatment. Here we evaluated a microRNA (miRNA) and its target responsible for sunitinib resistance. Using miRNA profiling, we identified miR-96-5p upregulation in tumors from sunitinib-resistant CCRCC patients. By bioinformatic analysis, PTEN was selected as a potential target of miR-96-5p, which showed low levels in tumors from sunitinib-resistant CCRCC patients. Furthermore, PTEN and miR-96-5p levels were negatively correlated in a large The Cancer Genome Atlas kidney renal clear cell carcinoma cohort and high miR-96 and low PTEN represented poor prognosis in this cohort. Additionally, four-week sunitinib treatment increased miR-96-5p and decreased PTEN only in tumors from a sunitinib-resistant patient-derived xenograft model. We found a novel miR-96-5p binding site in the PTEN 3' UTR and confirmed direct repression by luciferase reporter assay. Furthermore, we demonstrated that repression of PTEN by miR-96-5p increased cell proliferation and migration in sunitinib-treated cell lines. These results highlight the direct suppression of PTEN by miR-96-5p and that high miR-96-5p and low PTEN are partially responsible for sunitinib resistance and poor prognosis in CCRCC.