A novel HDAC6 inhibitor interferes microtubule dynamics and spindle assembly checkpoint and sensitizes cisplatin-induced apoptosis in castration-resistant prostate cancer.

BACKGROUND: Metastatic castration-resistant prostate cancer (CRPC), the most refractory prostate cancer, inevitably progresses and becomes unresponsive to hormone therapy, revealing a pressing unmet need for this disease. Novel agents targeting HDAC6 and microtubule dynamics can be a potential anti-CRPC strategy. METHODS: Cell proliferation was examined in CRPC PC-3 and DU-145 cells using sulforhodamine B assay and anchorage-dependent colony formation assay. Flow cytometric analysis of propidium iodide staining was used to determine cell-cycle progression. Cell-based tubulin polymerization assay and confocal immunofluorescence microscopic examination determine microtubule assembly/disassembly status. Protein expressions were determined using Western blot analysis. RESULTS: A total of 82 novel derivatives targeting HDAC6 were designed and synthesized, and Compound 25202 stood out, showing the highest efficacy in blocking HDAC6 (IC50, 3.5 nM in enzyme assay; IC50, 1.0 µM in antiproliferative assay in CRPC cells), superior to tubastatin A (IC50, 5.4 µM in antiproliferative assay). The selectivity and superiority of 25202 were validated by examining the acetylation of both α-tubulin and histone H3, detecting cell apoptosis and HDACs enzyme activity assessment. Notably, 25202 but not tubastatin A significantly decreased HDAC6 protein expression. 25202 prolonged mitotic arrest through the detection of cyclin B1 upregulation, Cdk1 activation, mitotic phosphoprotein levels, and Bcl-2 phosphorylation. Compound 25202 did not mimic docetaxel in inducing tubulin polymerization but disrupted microtubule organization. Compound 25202 also increased the phosphorylation of CDC20, BUB1, and BUBR1, indicating the activation of the spindle assembly checkpoint (SAC). Moreover, 25202 profoundly sensitized cisplatin-induced cell death through impairment of cisplatin-evoked DNA damage response and DNA repair in both ATR-Chk1 and ATM-Chk2 pathways. CONCLUSION: The data suggest that 25202 is a novel selective and potent HDAC6 inhibitor. Compound 25202 blocks HDAC6 activity and interferes microtubule dynamics, leading to SAC activation and mitotic arrest prolongation that eventually cause apoptosis of CRPC cells. Furthermore, 25202 sensitizes cisplatin-induced cell apoptosis through impeding DNA damage repair pathways.

Mechanistic study of dual-function inhibitors targeting topoisomerase II and Rad51-mediated DNA repair pathway against castration-resistant prostate cancer.

BACKGROUND: Castration-resistant prostate cancer (CRPC) is refractory to hormone treatment and the therapeutic options are continuously advancing. This study aims to discover the anti-CRPC effects and underlying mechanisms of small-molecule compounds targeting topoisomerase (TOP) II and cellular components of DNA damage repair. METHODS: Cell proliferation was determined in CRPC PC-3 and DU-145 cells using anchorage-dependent colony formation, sulforhodamine B assay and flow cytometric analysis of CFSE staining. Flow cytometric analyses of propidium iodide staining and JC-1 staining were used to examine the population of cell-cycle phases and mitochondrial membrane potential, respectively. Nuclear extraction was performed to detect the nuclear localization of cellular components in DNA repair pathways. Protein expressions were determined using Western blot analysis. RESULTS: A series of azathioxanthone-based derivatives were synthesized and examined for bioactivities in which WC-A13, WC-A14, WC-A15, and WC-A16 displayed potent anti-CRPC activities in both PC-3 and DU-145 cell models. These WC-A compounds selectively downregulated both TOP IIα and TOP IIß but not TOP I protein expression. WC-A13, WC-A14, and WC-A15 were more potent than WC-A16 on TOP II inhibition, mitochondrial dysfunction, and induction of caspase cascades indicating the key role of amine-containing side chain of the compounds in determining anti-CRPC activities. Furthermore, WC-A compounds induced an increase of γH2AX and activated ATR-Chk1 and ATM-Chk2 signaling pathways. P21 protein expression was also upregulated by WC-A compounds in which WC-A16 showed the least activity. Notably, WC-A compounds exhibited different regulation on Rad51, a major protein in homologous recombination of DNA in double-stranded break repair. WC-A13, WC-A14, and WC-A15 inhibited, whereas WC-A16 induced, the nuclear translocation of Rad51. CONCLUSION: The data suggest that WC-A compounds exhibit anti-CRPC effects through the inhibition of TOP II activities, leading to mitochondrial stress-involved caspase activation and apoptosis. Moreover, WC-A13, WC-A14, and WC-A15 but not WC-A16 display inhibitory activities of Rad51-mediated DNA repair pathway which may increase apoptotic effect of CRPC cells.

To control floating drug delivery system in a simulated gastric environment by adjusting the Shell layer formulation.

BACKGROUND: Gastroretentive drug delivery system (GDDS) are novel systems that have been recently developed for treating stomach diseases. The key function of all GDDS systems is to control the retention time in the stomach. However, research into the bulk density or entanglement of polymers, especially regarding their effects on drug float and release times, is scarce. METHODS: In this research, we prepared the floating core-shell beads carrying tetracycline. The ratio of chitosan and xanthan gum in the shell layer was changed to modify polymer compactness. Tetracycline was encapsulated in the alginate core. RESULTS: Using scanning electron microscopy (SEM) techniques, we observed that the shell formulation did not change the bead morphology. The cross-sectional images showed that the beads were highly porous. The interaction between anionic xanthan gum and cationic chitosan made the shell layer dense, resisting to the mass transfer in the shell layer. Due to the high mass transfer resistance to water penetration, the longer float and delivery time were caused by the dense surface of the beads. The cell culture demonstrated that floating core-shell beads were biocompatible. Importantly, the beads with tetracycline showed a significant prolonged anti-bacterial effect. CONCLUSION: Research results proved that the floating and releasing progress of core-shell beads can be well controlled by adjusting the shell layer formulation that could promote the function of gastroretentive drugs.

Preparation of Biomimetic 3D Gastric Model with Photo-Curing Resin and Evaluation the Growth of Helicobacter pylori.

Three-dimensional (3D) printing technology is now widely used in biomedical developments. Especially, photo-curing systems provide high resolution and precision. The current goal of biomedical 3D printing technology is the printing of human organs, but the current commercial photo-curable materials generally have high mechanical strength that cannot meet the mechanical properties of the object to be printed. In this research, a gastric model was printed using a photo-curing 3D printing technique. To mimic the wrinkle pattern of human gastric tissue, cis-1,4 polyisoprene with different reactive diluents was mixed and identified a formulation that produced a print with human gastric softness. This research discussed the effect of the Young's modulus of the material and elucidated the relationship between the degree of conversion rate and viscosity. After modifying the cis-1,4 polyisoprene surface from hydrophobic to hydrophilic, we then evaluated its adhesion efficiency for gastric mucin and the gastrointestinal-inhabiting bacterium Helicobacter pylori.

Mesophase Pitch-Derived Carbons with High Electronic and Ionic Conductivity Levels for Electric Double-Layer Capacitors.

We develop a temperature-programmed pretreatment strategy for converting aliphatic-rich petroleum pitch into a mesophase framework, which can then be activated using KOH to produce high-performance carbons for electric double-layer capacitors (EDLCs). In the pretreatment of pitch at an optimal temperature, both the temperature ramp and holding time influence the mesophase structure, which governs the pore structure and crystallinity of the resulting activated carbon. High carbon microporosity is beneficial to capacitance maximization but detrimental to ion transport. To resolve this problem, we develop a multistep ramp incorporating aliphatic species into the aromatic framework during mesophase formation. This incorporation process produces a mesophase framework that can be activated to form carbons with high crystallinity, thereby enhancing electronic conductivity and hierarchical porosity, which improves ionic conductivity. The resulting carbon electrode is used to assemble a symmetric EDLC, which exhibits a capacitance of 160 F g-1 and excellent high-rate retention in a propylene carbonate solution of N,N-diethyl-N-methylethanaminium tetrafluoroborate. The EDLC delivers a superior specific energy of 40 Wh kg-1 (based on the total carbon mass) within a voltage range of 0-2.7 V and sustained a high energy of 24 Wh kg-1 at a high power of 50 kW kg-1. The findings of this study demonstrate that incorporating aliphatic species into aromatic mesophase frameworks plays a crucial role in regulating the crystallinity and pore structure of pitch-derived carbons for charge storage.