Selective targeting of cancer cells using a hydrogen peroxide-activated Hsp90 inhibitor.

Heat shock protein 90 (Hsp90) plays an important role in cancer cell proliferation, survival, and migration by regulating the maturation and stabilization of numerous oncoproteins. Despite significant efforts in developing Hsp90 inhibitors, none of these have been approved for clinical use, mostly due to toxicity, such as liver, cardiac, and retinal toxicity. To avoid undesirable toxicity, we herein report a hydrogen peroxide-activated Hsp90 inhibitor, Boro-BZide (3), which is capable of selectively targeting cancer cells over normal cells. Boro-BZide (3) can be activated by high levels of hydrogen peroxide, releasing its parent active Hsp90 inhibitor. The mechanism of action was determined by a series of experiments including fluorescence polarization assay, cell viability assay, western blotting, high-pressure liquid chromatography (HPLC), and fluorescence-activated cell sorting (FACS) analysis. These efforts ultimately led to the identification of a novel hydrogen peroxide-activated Hsp90 prodrug with improved therapeutic index, which was less prone to furnish unwanted adverse effects. This hydrogen peroxide-responsive prodrug strategy will be beneficial for overcoming the toxicity hurdles of Hsp90 inhibitors for clinical application.

Development of Thiazolidinedione-Based HDAC6 Inhibitors to Overcome Methamphetamine Addiction.

Thiazolidinedione is a five-membered heterocycle that is widely used in drug discovery endeavors. In this study, we report the design, synthesis, and biological evaluation of a series of thiazolidinedione-based HDAC6 inhibitors. In particular, compound 6b exerts an excellent inhibitory activity against HDAC6 with an IC50 value of 21 nM, displaying a good HDAC6 selectivity over HDAC1. Compound 6b dose-dependently induces the acetylation level of α-tubulin via inhibition of HDAC6 in human neuroblastoma SH-SY5Y cell line. Moreover, compound 6b efficiently reverses methamphetamine-induced morphology changes of SH-SY5Y cells via regulating acetylation landscape of α-tubulin. Collectively, compound 6b represents a novel HDAC6-isoform selective inhibitor and demonstrates promising therapeutic potential for the treatment of methamphetamine addiction.

Nano-mechanical reinforcement in drug-resistant ovarian cancer cells.

The mechanical properties of cells are considered promising biomarkers for the early detection of cancer and the testing of drug efficacy against it. Nevertheless, generalized correlations between drug resistance and the nano-mechanical properties of cancer cells are yet to be defined due to the lack of necessary studies. In this study, we conducted atomic force microscopy (AFM)-based nano-mechanical measurements of cisplatin-sensitive (A2780) and cisplatin-resistant (A2780cis) ovarian cancer cells. The difference in the efficacy of cisplatin between A2780 and A2780cis was confirmed in the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. We observed that the cisplatin-resistant ovarian cancer cells were more motile than cisplatin-sensitive cells based on the results of the wound closure experiment, and the AFM experiments showed that drug resistance induced nano-mechanical stiffening of the ovarian cancer cells. Increased mechanical stiffness caused by cisplatin resistance was consistent with the confocal microscopy images showing more distinct actin stress fibers in A2780cis than in A2780 cells. The down regulation of vinculin implicated the actin-driven elongation as a major motile mode for A2780cis cells. Our results consistently indicated that the acquisition of drug resistance in ovarian cancer cells induces an extensive reorganization of the actin cytoskeleton, which governs the cellular mechanical properties, motility, and possibly intracellular drug transportation.

Evodiae Fructus extract suppresses inflammatory response in HaCaT cells and improves house dust mite-induced atopic dermatitis in NC/Nga mice.

This study was conducted to assess the effect of Evodiae Fructus 70% ethanol extract (EFE) on the pathology of atopic dermatitis using in vitro and in vivo models. The major compounds in EFE were identified by ultra-performance liquid chromatography with tandem mass spectrometry as rutaecarpine, evodiamine, evodol, dehydroevodiamine, limonin, synephrine, evocarpine, dihydroevocarpine, and hydroxyevodiamine. EFE significantly decreased chemokine levels in tumor necrosis factor-α/interferon-γ-stimulated HaCaT cells. In house dust mite-treated NC/Nga mice, topical application of EFE significantly decreased the dermatitis score, epidermal hyperplasia and thickening, mast cell infiltration, and plasma levels of histamine and corticosterone. Thymic stromal lymphopoietin, CD4+ T cells, interleukin-4, and intercellular adhesion molecule-1 expression in the lesioned skin was reduced in the treated mice. The mechanism of EFE was elucidated using transcriptome analysis, followed by experimental validation using Western blotting in HaCaT cells. EFE down-regulated the activation of Janus kinase (JAK)-signal transducers and activators of transcription (STAT) and mitogen-activated protein kinases (MAPK) signaling pathways in HaCaT cells. EFE improves atopic dermatitis-like symptoms by suppressing inflammatory mediators, cytokines, and chemokines by regulating the JAK-STAT and MAPK signaling pathways, suggesting its use as a potential agent for the treatment of atopic dermatitis.

Daeshiho-tang attenuates inflammatory response and oxidative stress in LPS-stimulated macrophages by regulating TLR4/MyD88, NF-κB, MAPK, and Nrf2/HO-1 pathways.

Daeshiho-tang (DSHT), a traditional herbal formula with diverse pharmacological effects, has shown promise in medicine owing to its anti-hypertensive, anti-diabetic, and anti-inflammatory properties. However, the precise molecular mechanism underlying these effects remains unclear. Thus, we investigated the effect of DSHT on inflammatory response and oxidative stress to understand its molecular mechanism using lipopolysaccharide (LPS)-induced macrophage (RAW 264.7) cells. DSHT decreased the contents of nitric oxide (NO) and prostaglandin E2 (PGE2) through downregulating inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expressions. DSHT suppressed the LPS-induced TLR4 as well as MyD88, subsequently suppressing the NF-κB activation and the phosphorylation of MAPK (p38, ERK, and JNK). Radical scavenging activity results revealed a dose-dependent response of DSHT with diminished ABTS activity, a hallmark of oxidative stress potential. Furthermore, DSHT enhanced Nrf2 and HO-1 expression in response to LPS. Collectively, our findings indicated that DSHT exert anti-inflammatory effect and regulating oxidative stress by modulating TLR4/MyD88, NF-κB, MAPK, and Nrf2/HO-1 pathways, consequently can provide potential therapeutic strategy for the prevention and treatment of inflammation and oxidative stress-related diseases.

Design, synthesis, and biological evaluation of histone deacetylase inhibitor with novel salicylamide zinc binding group.

INTRODUCTION: Histone deacetylases (HDACs) have emerged as important therapeutic targets for various diseases, such as cancer and neurological disorders. Although a majority of HDAC inhibitors use hydroxamic acids as zinc binding groups, hydroxamic acid zinc-binding groups suffer from poor bioavailability and nonspecific metal-binding properties, necessitating a new zinc-binding group. Salicylic acid and its derivatives, well-known for their therapeutic value, have also been reported to chelate zinc ions in a bidentate fashion. This drew our attention towards replacing hydroxamic acid with salicylamide as a zinc-binding group. METHODS: In this study, for the first time, compound 5 possessing a novel salicylamide zinc-binding group was synthesized and evaluated biologically for its ability to inhibit various HDAC isoforms and induce acetylation upon α-tubulin and histone H3 among MDA-MB-231 cells. RESULTS: Compound 5 exhibits selective inhibition against class I HDAC isoforms (HDAC1, 2, and 3) over class II and IV HDAC isoforms (HDAC4, 6, and 11). The exposure of MDA-MB-231 cells to compound 5 efficiently induced the acetylation of more histone H3 than α-tubulin, suggesting that compound 5 is a class I selective HDAC inhibitor. Moreover, the molecular docking study indicated that the salicylamide zinc-binding group of compound 5 coordinates the active zinc ion of class I HDAC2 in a bidentate fashion. CONCLUSION: Overall, salicylamide represents a novel zinc-binding group for the development of class I selective HDAC inhibitors. GRAPHICAL ABSTRACT: (http://links.lww.com/MD/G668).

The targeted inhibition of Hsp90 by a synthetic small molecule, DPide offers an effective treatment strategy against TNBCs.

Triple-negative breast cancers (TNBCs) are the most aggressive and metastatic subtype of breast cancers and exhibit poor clinical outcome due to the lack of drug target receptors such as estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor 2 (Her2). The limited effectiveness of therapeutic options and the poor prognosis of TNBC patients emphasize the urgent need for identifying new therapeutic agents. In this regard, heat shock protein 90 (Hsp90) has emerged as a promising therapeutic target for the treatment of TNBCs. Hsp90 is a molecular chaperone that regulates the folding, stability, and function of many oncogenic proteins. Hence, the inhibition of Hsp90 chaperone function leads to a simultaneous blockage of multiple signaling pathways in the proliferation and survival of cancers. In the present study, we performed the design, synthesis, and biological evaluation of Hsp90 inhibitors and found that a synthetic small molecule, DPide exerted a potent anticancer activity against TNBC cell line, MDA­MB­231 and non­small cell lung cancer (NSCLC) cell line, H1975 with GI50 values of 0.478 and 1.67 µM, respectively. Soft­agar colony formation assay also revealed that DPide suppressed the anchorage­independent growth of MDA­MB­231 cells. Western blot analysis indicated that the treatment of MDA­MB­231 cells with DPide induced the proteasomal degradation of EGFR, Her2, Met, Akt, c­Raf, and Cdk4 and the consequent cleavage of PARP, leading to apoptotic cell death. DPide also inhibited the migration and MMP9 activity of MDA­MB­231 cells, suggesting that the metastatic potential of TNBCs could be suppressed by DPide. Collectively, DPide offers an effective therapeutic option for the treatment TNBCs.

Design, synthesis, and biological evaluation of a series of resorcinol-based N-benzyl benzamide derivatives as potent Hsp90 inhibitors.

Heat shock protein 90 (Hsp90) is a ubiquitous molecular chaperone that is responsible for the stabilization and maturation of many oncogenic proteins. Therefore, Hsp90 has emerged as an attractive target in the field of cancer chemotherapy. In this study, we report the design, synthesis, and biological evaluation of a series of Hsp90 inhibitors. In particular, compound 30f shows a significant Hsp90α inhibitory activity with IC50 value of 5.3 nM and an excellent growth inhibition with GI50 value of 0.42 µM against non-small cell lung cancer cells, H1975. Compound 30f effectively reduces the expression levels of Hsp90 client proteins including Her2, EGFR, Met, Akt, and c-Raf. Consequently, compound 30f promotes substantial cleavages of PARP, Caspase 3, and Caspase 8, indicating that 30f induces cancer cell death via apoptotic pathway. Moreover, cytochrome P450 assay indicates that compound 30f has weak inhibitory effect on the activities of five major P450 isoforms (IC50 > 5 µM for 1A2, 2C9, 2C19, 2D6, and 3A), suggesting that clinical interactions between 30f and the substrate drugs of the five major P450 isoforms are not expected. Compound 30f also inhibits the tumor growth in a mouse xenograft model bearing subcutaneous H1975 without noticeable abnormal behavior and body weight changes. The immunostaining and western immunoblot analysis of EGFR, Met, Akt in xenograft tissue sections of tumor further demonstrate a good agreement with the in vitro results.

A novel chalcone-based molecule, BDP inhibits MDA­MB­231 triple-negative breast cancer cell growth by suppressing Hsp90 function.

Triple-negative breast cancer (TNBC) is a molecularly diverse and heterogeneous disease and the molecular heterogeneity of TNBC increases the difficulty in improving survival rates. To date, therapeutic approaches for the treatment of TNBC such as hormonal chemotherapy and trastuzumab-based therapy have been limited by the lack of target receptors such as estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (Her2), emphasizing the urgent need for identifying new therapeutic options. In this regard, heat shock protein 90 (Hsp90) has emerged as an attractive therapeutic target for TNBC. Hsp90 plays a central role in regulating correct folding, stability, and function of numerous oncogenic proteins. In the present study, we evaluated the in vitro effect of a small molecule Hsp90 inhibitor, (E)-3-(2-bromo-3,4,5-trimethoxyphenyl)-1-(2,4-dihydroxyphenyl)prop-2-en-1-one (BDP) on TNBC cell line, MDA­MB­231. This study indicated that BDP efficiently inhibited the growth of MDA­MB­231 cells in a dose- and time-dependent manner. BDP induced overall degradation of multiple oncogenic proteins including EGFR, Her2, Met, Akt, c­Raf, and Cdk4, consequently leading to apoptotic cell death. The flow cytometric analysis revealed that BDP promoted cell cycle arrest at G2/M phases. Moreover, BDP treatment attenuated the migration of MDA­MB­231 cells and impaired MMP9 activity, which are essential processes for tumor metastasis. Collectively, BDP represents a new class of Hsp90 inhibitor and shows therapeutic potential for TNBC treatment.

Chalcone-templated Hsp90 inhibitors and their effects on gefitinib resistance in non-small cell lung cancer (NSCLC).

The molecular chaperone Hsp90 has emerged as an attractive cancer therapeutic target due to its role in cellular homeostasis by modulating the stabilization and maturation of many oncogenic proteins. In this study, we designed and synthesized a series of Hsp90 inhibitors that hybridized NVP-AUY992 (2) and PU3 (3) in the chalcone scaffold using a structure-based approach. Our results indicate that compound 1g inhibited the proliferation of gefitinib-resistant non-small cell lung cancer (H1975) cells, downregulated the expression of client proteins of Hsp90 including EGFR, MET, Her2 and Akt, and up-regulated the expression of Hsp70. The compound 1g represents a new class of Hsp90 inhibitors with a chalcone structure. The design, synthesis, and evaluation of 1g are described herein.

Targeting the entry region of Hsp90's ATP binding pocket with a novel 6,7-dihydrothieno[3,2-c]pyridin-5(4H)-yl amide.

The molecular chaperone Hsp90 plays an important role in cancer cell survival and proliferation by regulating the maturation and stabilization of numerous oncogenic proteins. Due to its potential to simultaneously disable multiple signaling pathways, Hsp90 has emerged as an attractive therapeutic target for cancer treatment. In this study, the design, synthesis, and biological evaluation of a series of Hsp90 inhibitors are described. Among the synthetic compounds, 6,7-dihydrothieno [3,2-c]pyridin-5(4H)-yl amide 19 exhibits a remarkable binding affinity to the N-terminus of Hsp90 in a fluorescence polarization (FP) binding assay (IC50 = 50.3 nM). Furthermore, it effectively inhibits the proliferation of H1975 non-small cell lung cancer (NSCLC) and Skbr3 breast cancer cell lines with GI50 values of 0.31 µM and 0.11 µM, respectively. Compound 19 induces the degradation of the Hsp90 client proteins including EGFR, Her2, Met, c-Raf, and Akt, and consequently promotes apoptotic cancer cell death. Compound 19 also inhibits the growth of H1975 xenografts in NOD-scid IL2R gammanull mice without any apparent body-weight loss. The immunohistologic evaluation indicates that compound 19 decreases the expression of Akt in xenograft tumor tissue via an inhibition of the Hsp90 chaperon function. Additionally, the cytochrome P450 assay indicates that compound 19 has no effect on the activities of five major P450 isoforms (IC50 > 50 µM for 1A2, 2C9, 2C19, 2D6, and 3A), suggesting that clinical interactions between compound 19 and the substrate drugs of the five major P450 isoforms are not expected. Overall, compound 19 represents a new class of Hsp90 inhibitor with its 6,7-dihydrothieno[3,2-c]pyridin-5(4H)-yl-amide structure, and it has the therapeutic potential to overcome drug resistance in cancer chemotherapy.