Targeting histone deacetylases for cancer therapy: Trends and challenges

Dysregulation of histone deacetylases (HDACs) is closely related to tumor development and progression. As promising anticancer targets, HDACs have gained a great deal of research interests and two decades of effort has led to the approval of five HDAC inhibitors (HDACis). However, currently traditional HDACis, although effective in approved indications, exhibit severe off-target toxicities and low sensitivities against solid tumors, which have urged the development of next-generation of HDACi. This review investigates the biological functions of HDACs, the roles of HDACs in oncogenesis, the structural features of different HDAC isoforms, isoform-selective inhibitors, combination therapies, multitarget agents and HDAC PROTACs. We hope these data could inspire readers with new ideas to develop novel HDACi with good isoform selectivity, efficient anticancer effect, attenuated adverse effect and reduced drug resistance.

Effects and molecular mechanism of histone methyltransferase enhancer of zeste homolog 2 on regulating sepsis-induced T cell dysfunction / 中华危重病急救医学

Objective:To investigate the effect and mechanism of histone methyltransferase enhancer of zeste homolog 2 (EZH2) on sepsis-induced T cell dysfunction.Methods:Twenty-four male C57BL/6 mice were divided into three groups randomly: sham operated group, sepsis model group [cecum ligation and puncture (CLP)+dimethyl sulfoxide (DMSO) group] and EZH2 selective inhibitor treated group (CLP+GSK126 group), with 8 mice in each group. Sepsis murine model was reproduced by CLP. CLP+DMSO group and CLP+GSK126 group were treated with DMSO or GSK126 (10 mg/kg) respectively right after surgery through intraperitoneal injection. The mice were sacrificed 24 hours after operation, and the mesenteric lymph nodes were collected. The expression of EZH2, apoptosis rates, cell proliferation marker ki-67 antigen positive T lymphocytes (ki-67 + cell), interferon-γ positive T lymphocytes (IFN-γ + cell), programmed death receptor-1 positive T lymphocytes (PD-1 + cell) and programmed death-ligand 1 positive T lymphocytes (PD-L1 + cell) were determined by flow cytometry. Results:Compared with sham operated group, the expression of EZH2 in T lymphocytes was up-regulated on mesenteric lymph nodes of CLP+DMSO group. Compared with CLP+DMSO group, the ratio of CD3 + T lymphocytes in CLP+GSK126 group was up-regulated (0.70±0.02 vs. 0.50±0.07, P < 0.01), indicating that the EZH2 inhibitor could increase the number of T lymphocytes in lymph nodes of septic mice; the ratio of ki-67 + cells in CD4 + and CD8 + T lymphocytes in CLP+GSK126 group was increased (CD4 +: 0.74±0.05 vs. 0.63±0.04, CD8 +: 0.82±0.06 vs. 0.70±0.04, both P < 0.05), indicating that the EZH2 inhibitor could increase the ratio of T lymphocytes with high proliferative activity in lymph nodes of septic mice. However, no significant difference was found on both CD4 + and CD8 + T lymphocytes apoptosis rates in the mesenteric lymph nodes of mice between CLP+GSK126 group and CLP+DMSO group [CD4 +: (21.53±2.87)% vs. (20.48±3.21)%, CD8 +: (8.34±1.02)% vs. (7.71±1.38)%, both P > 0.05], indicating that no extra T lymphocytes apoptosis was induced by EZH2 inhibitor. Compared with CLP+DMSO group, the ratios of IFN-γ + CD4 + and IFN-γ + CD8 + T lymphocytes were increased in CLP+GSK126 group (IFN-γ +CD4 +: 0.31±0.11 vs. 0.14±0.06, IFN-γ +CD8 +: 0.30±0.10 vs. 0.13±0.06, both P < 0.05), suggesting that secretion of IFN-γ in lymph nodes by sepsis T lymphocytes was augmented after EZH2 inhibitor administration. Furthermore, compared with CLP+DMSO group, the ratio of PD-1 + cell in CD8 + T lymphocyte was down-regulated in CLP+GSK126 group (0.092±0.006 vs. 0.135±0.004, P < 0.01), suggesting that EZH2 inhibitor restrained the PD-1 expression on sepsis lymphoid node CD8 + T lymphocytes, however, it had no significant effect on PD-L1 + cells. Conclusion:EZH2, regulates sepsis-induced T lymphocyte dysfunction, possibly through modulating the expression of PD-1.

Atractylenolide-I covalently binds to CYP11B2, selectively inhibits aldosterone synthesis, and improves hyperaldosteronism

Hyperaldosteronism is a common disease that is closely related to endocrine hypertension and other cardiovascular diseases. Cytochrome P450 11B2 (CYP11B2), an important enzyme in aldosterone (ALD) synthesis, is a promising target for the treatment of hyperaldosteronism. However, selective inhibitors targeting CYP11B2 are still lacking due to the high similarity with CYP11B1. In this study, atractylenolide-I (AT-I) was found to significantly reduce the production of ALD but had no effect on cortisol synthesis, which is catalyzed by CYP11B1. Chemical biology studies revealed that due to the presence of Ala320, AT-I is selectively bound to the catalytic pocket of CYP11B2, and the C8/C9 double bond of AT-I can be epoxidized, which then undergoes nucleophilic addition with the sulfhydryl group of Cys450 in CYP11B2. The covalent binding of AT-I disrupts the interaction between heme and CYP11B2 and inactivates CYP11B2, leading to the suppression of ALD synthesis; AT-I shows a significant therapeutic effect for improving hyperaldosteronism.

Sodium Channel NaV1. 7 and Neuropathic Pain / 中国生物化学与分子生物学报

Sodium channel Nav1. 7 is one of the subtypes of voltage-gated sodium channel. Most of it is expressed on the nociceptors of small C fibers in dorsal root ganglion (DRG). It has the characteristics of slow opening and slow closing of inactivation. It can produce a large amount of ramp current, reduce the threshold of action potential in sensory neurons, and amplify the external small and slow depolarization ramp current. Thus, it can increase the excitability of neurons and play a key role in the generation, transmission and regulation of pain. With the deepening of genetic research, Nav1. 7 channel has become a particularly attractive drug target in new analgesic therapy due to its function acquired mutation and function deletion mutation. However, the study found that Nav1. 7 channel improves neuronal excitability and participates in neuropathic pain through different ways in neuropathic pain caused by different factors, which has brought great obstacles to the research and development of Nav1. 7 selective inhibitors. Although the existing Nav1. 7 selective inhibitors have effective analgesic effects without obvious side effects or addiction problems, it is extremely difficult to find Nav1. 7 selective ligands. In addition, the existing Nav1. 7 selective inhibitors also differ in inhibitory efficacy, targeting, safety and feasibility due to different types of neuropathic pain. It is suggested that finding the general mechanism of Nav1. 7 channel acting on different neuropathic pain or the specific receptor binding site of Nav1. 7 channel may be the main direction of the research and development of Nav1. 7 selective inhibitors in the future. This paper briefly reviews the main role of Nav1. 7 channel in neuropathic pain caused by different factors.

Cost-effectiveness of Non-steroidal Anti-inflammatory Drugs Adjusting for Upper and Lower Gastrointestinal Toxicities in Rheumatoid Arthritis Patients

OBJECTIVE: This study was performed to assess the cost-effectiveness of cyclooxygenase-2 (COX2)-selective inhibitor, non-selective non-steroidal anti-inflammatory drugs (NSAIDs), and non-selective NSAID with proton pump inhibitors (PPIs) while considering upper and lower gastrointestinal (GI) safety in patients with rheumatoid arthritis (RA). METHODS: A Markov model was used to estimate the costs and effectiveness. Estimates of therapeutic efficacy and upper/lower GI safety were based on results from large randomized controlled trials. The main outcome measure was cost effectiveness, based on the quality-adjusted life years (QALYs) gained. Safety parameters included clinical upper GI symptoms, uncomplicated ulcer, upper GI bleeding, upper GI perforation, clinical lower GI symptoms, lower GI bleeding, and lower GI perforation. Cost data were obtained from patients treated in a tertiary referral center in Korea. RESULTS: The expected three year cost was 3,052,800 Korean won (KRW) for COX2-selective inhibitor, 3,170,800 KRW for nonselective NSAID, and 3,325,900 KRW for non-selective NSAID with PPI. QALYs were 2.87446, 2.85320, and 2.85815, respectively. The total cost for COX2-selective inhibitor use was lower than non-selective NSAID, but QALY was higher, indicating that the incremental cost effectiveness ratio of COX2-selective inhibitor is superior. CONCLUSION: COX2-selective inhibitor has reasonable cost-effectiveness adjusted for upper and lower GI toxicity for patients with RA in Korea.

Advances in histone deacetylase 8 selective inhibitors / 中国药科大学学报

@#Histone deacetylase 8(HDAC8)is a zinc-dependent class I histone deacetylase, closely related to human pathophysiology. HDAC8 involves in various critical signaling networks and is implicated as a therapeutic target in various diseases, including cancer, X-linked intellectual disability and parasitic infections. More and more selective HDAC8 inhibitors have been developed based on deepening study of its well-characterized crystal structure. They are mainly divided into several categories such as phenyl hydroxamic acids, indoles, ortho-aryl-N-hydroxycinnamides, azetidinones etc. . Current challenges remain in the development of potent selective inhibitors that would specifically target HDAC8 with fewer adverse effects compared with pan-HDAC inhibitors. Herein, we reviewed the progress in the study of structure and functions of HDAC8 as well as the development of selective HDAC8 inhibitors.

EFFICACY OF SEQUENTIAL TREATMENT WITH ADDUCTOR CANAL NERVE BLOCK AND CYCLOOXYGENASE 2 SELECTIVE INHIBITOR AFTER TOTAL KNEE ARTHROPLASTY / 中国修复重建外科杂志

OBJECTIVE: To investigate the efficacy of sequential treatment with adductor canal nerve block (ACNB) and cyclooxygenase 2 (COX-2) selective inhibitor (parecoxib and celecoxib) after primary total knee arthroplasty (TKA). METHODS: Between January 2015 and December 2015, 90 osteoarthritis patients who met the inclusion criteria were treated, and randomly divided into 3 groups:ACNB+COX-2 group (group A, n=30), COX-2 group (group B, n=30), and control group (group C, n=30). There was no significant difference in gender, age, body mass index, side, and osteoarthritis duration between groups (P>0.05), and the data were comparable. ACNB was used in group A at the end of TKA. Intravenous injection of parecoxib (40 mg per 12 hours) was administrated at the first three postoperative days, and followed by oral celecoxib (200 mg per 12 hours) until 6 weeks after operation in groups A and B; while placebo was given at the same time point in group C. Oral tramadol or intravenous morphine, as remedial measures, were introduced when patients had a visual analogue scale (VAS) score more than 4. The following indicators were compared between groups:the operative time, drainage volume at 24 hours after operation, length of hospital stay, and incidence of side effect; VAS pain scores, morphine consumption, range of motion (ROM) of the knee joint, and inflammatory cytokines levels at pre-operation and at 1 day, 2 days, 3 days, 1 week, 2 weeks, 4 weeks, and 6 weeks after operation; morphine consumption within first 24 hours and at 24 hours to 6 weeks after operation; the American Hospital for Special Surgery (HSS) score at 1, 2, 4, and 6 weeks after operation; and the serum coagulation parameters at pre-operation, and at 1, 3, and 14 days after operation. RESULTS: The length of hospital stay was significantly shorter and the incidence of postoperative nausea and vomiting was significantly lower in groups A and B than group C (P0.05). CONCLUSIONS: Sequential treatment with ACNB and COX-2 selective inhibitor is a safe and effective approach for postoperative pain management after primary TKA, and it can alleviate postoperative pain, promote the joint function recovery, and reduce the risk of adverse reactions.

Cyclooxygenase-2 Inhibitors and Cardivascular Risk / 한양의대학술지

Serious concerns about the cardiovascular safety of rofecoxib had been present since the VIOXX(R) Gastrointestinal Outcomes Research (VIGOR) study first suggested that the drug may increase the risk of myocardial infarction. Subsequent data from major observational studies further implicated the association of rofecoxib with arterial thromboembolic disease. In September 2004, rofecoxib was withdrawn from the worldwide market based on the safety findings of the Adenomatous Polyp Prevention on VIOXX (APPROVe) study, which indicated an increase risk of myocardial infarction and stroke among subjects randomized to rofecoxib. In December 2004, the results of the Adenoma Prevention with Celecoxib (APC) study demonstrated a dose-related increase in the risk of cardiovascular events among patients randomized to celecoxib when compared with placebo. Two other large prospective prevention studies of celecoxib, the Prevention of Spontaneous Adenomatous Polyps (Pre SAP) trial and the Alzheimer's Disease Antiinflammatory Prevention Trial (ADAPT) did not show any sign of increased cardiovascular risk. None of the reported randomized trials studying any COX-2 selective imhibitor, thus far, has been specifically designed to examine cardiovascular outcomes. Hence, no cardiovascular hypotheses have yet been formally tested. Long-term and adequately powered prospective randomized clinical trials in relevant patient populations with clinically appropriate pre-specified cardiovascular end-points, ideally comparing COX-2 selective inhibitors with traditional NSAIDs, are required. Until these trials are completed, careful risk:benefit analysis of any putative increase in cardiovascular risk versus known gastrointestinal benefit for individual agents needs to be undertaken.