Design,synthesis and activity evaluation of indole-based double – Branched HDAC1 inhibitors

Histone deacetylases inhibitors (HDACIs) represents effective treatments for cancer. In continuing our efforts to develop novel and potent HDACIs, a series of N-hydroxycinnamamide-based HDACIs with aromatic ring and various aliphatic linker have been successfully designed and synthesized. Biological evaluations established that compounds 4h, 4i, 4j, 4l, 4r showed superior inhibition on histone deacetylase and antiproliferative activity in some solid tumor cell lines [HeLa, SK-N-BE(2), PC-3] compared to the known inhibitor SAHA. Among these analogs, 4l exhibited selectivity to HDAC1.     

Structure and property based design, synthesis and biological evaluation of γ-lactam based HDAC inhibitors

Histone deacetylases (HDACs) are involved in post-translational modification and gene expression. Cancer cells recruited amounts of HDACs for their survival by epi-genetic down regulation of tumor suppressor genes. HDACs have been the promising targets for treatment of cancer, and many HDAC inhibitors have been investigated nowadays. In previous study, we synthesized δ-lactam core HDAC inhibitors which showed potent HDAC inhibitory activities as well as cancer cell growth inhibitory activities. Through QSAR study of the δ-lactam based inhibitors, the smaller core is suggested as more active than larger one because it fits better in narrow hydrophobic tunnel of the active pocket of HDAC enzyme. The smaller γ-lactam core HDAC inhibitors were designed and synthesized for biological and property optimization. Phenyl, naphthyl and thiophenyl groups were introduced as the cap groups. Hydrophobic and bulky cap groups increase potency of HDAC inhibition because of hydrophobic interaction between HDAC and inhibitors. In overall, γ-lactam based HDAC inhibitors showed more potent than δ-lactam analogues.     

Structure and property based design, synthesis and biological evaluation of γ-lactam based HDAC inhibitors: part II

Histone deacetylases (HDACs) are involved in post-translational modification and epi-genetic expression, and have been the intriguing targets for treatment of cancer. In previous study, we reported synthesis and the biological preliminary results of γ-lactam based HDAC inhibitors. Based on the previous results, smaller γ-lactam core HDAC inhibitors are more active than the corresponding series of larger δ-lactam based analogues and the hydrophobic and bulky cap groups are required for better potency which decreased microsomal stability. Thus, γ-lactam analogues with methoxy, trifluoromethyl groups of ortho-, meta-, para-positions of cap group were prepared and evaluated their biological potency. Among them, trifluoromethyl analogues, which have larger lipophilicity, showed better HDAC inhibitory activity than other analogues. In overall, lipophilicity leads to increase hydrophobic interaction between surface of HDAC active site and HDAC inhibitor, improves HDAC inhibitory activity.     

VPA inhibits renal cancer cell migration by targeting HDAC2 and down-regulating HIF-1α

Cell migration plays major roles in human renal cancer-related death, but the molecular mechanisms remain unclear. Valproic acid (VPA) is a broad-spectrum inhibitor of class I and II histone deacetylases and shows great anticancer activity in a variety of human cancers. In this study, we found that VPA significantly inhibited cell migration but not proliferation of human renal cancer ACHN cells. Mechanistic studies found that VPA significantly inhibited the expression of HIF-1α. Knockdown of HIF-1α could obviously inhibited cell migration, while over-expression of HIF-1α markedly rescued the inhibition of VPA on cell migration. Further studies found that knockdown of HDAC2 completely mimicked the effects of VPA on HIF-1α and cell migration, and over-expression of HIF-1α could also rescue the effects of HDAC2 knockdown on cell migration. Collectively, these results indicated that the potential of specific inhibition of HDAC2 by small molecular chemicals may lead to future therapeutic agents in human renal cancer treatment.     

果蝇组蛋白去乙酰化酶HDAC1和HDAC3选择性调控形态发生素靶基因转录

在真核细胞中,组蛋白的乙酰化状态对于基因转录的正常进行具有重要的调控作用。组蛋白的乙酰化修饰由组蛋白乙酰转移酶(histone acetyltransferases,HATs)执行,这种修饰是动态的、可逆的,负责去乙酰化修饰的酶是组蛋白去乙酰化酶(histone deacetylases,HDACs),推测HDACs可能通过影响组蛋白的乙酰化状态在基因的转录过程中发挥调控作用。该文以组蛋白去乙酰化酶HDAC1和HDAC3为对象,研究了它们在果蝇翅膀发育过程中对Wg(Wingless)、Hh(Hedgehog)以及Dpp(Decapentaplegic)信号通路下游靶基因转录的调控作用。结果发现,HDAC1功能缺失可导致Dpp下游靶基因Omb(optomotor-blind)和Hh下游靶基因Ptc(patched)的表达上调。Real-time quantitative PCR(RT-q PCR)结果显示,在HDAC1基因敲除的果蝇中,Ptc、Ci(cubitus interruptus)以及Omb的转录水平增加。HDAC3缺失导致Sal(spalt)的表达上调。RT-q PCR结果证实了HDAC3基因敲除果蝇的Sal转录增加,同时发现Vg(vestigial)的转录下降。而过表达HDAC1或HDAC3对下游靶基因的表达则没有影响。综上所述,该研究表明,HDAC1和HDAC3可以选择性地调控形态发生素下游靶基因的转录。     

Wogonin Has Multiple Anti-Cancer Effects by Regulating c-Myc/SKP2/Fbw7α and HDAC1/HDAC2 Pathways and Inducing Apoptosis in Human Lung Adenocarcinoma Cell Line A549

Wogonin is a plant monoflavonoid which has been reported to inhibit cell growth and/or induce apoptosis in various tumors. The present study examined the apoptosis-inducing activity and underlying mechanism of action of wogonin in A549 cells. The results showed that wogonin was a potent inhibitor of the viability of A549 cells. Apoptotic protein changes detected after exposure to wogonin included decreased XIAP and Mcl-1 expression, increased cleaved-PARP expression and increased release of AIF and cytotchrome C. Western blot analysis showed that the activity of c-Myc/Skp2 and HDAC1/HDAC2 pathways, which play important roles in tumor progress, was decreased. Quantitative PCR identified increased levels of c-Myc mRNA and decreased levels of its protein. Protein levels of Fbw7α, GSK3β and Thr58-Myc, which are involved in c-Myc ubiquitin-dependent degradation, were also analyzed. After exposure to wogonin, Fbw7α and GSK3β expression decreased and Thr58-Myc expression increased. However, MG132 was unable to prevent c-Myc degradation. The present results suggest that wogonin has multiple anti-cancer effects associated with degradation of c-Myc, SKP2, HDAC1 and HDAC2. Its ability to induce apoptosis independently of Fbw7α suggests a possible use in drug-resistance cancer related to Fbw7 deficiency. Further studies are needed to determine which pathways are related to c-Myc and Fbw7α reversal and whether Thr58 phosphorylation of c-Myc is dependent on GSK3β.     

Property based optimization of δ-lactam HDAC inhibitors for metabolic stability

The novel δ-lactam based HDAC inhibitor, KBH-A118 (3) shows a good HDAC enzyme and cancer cell growth inhibitory activities but has undesirable pharmacokinetics profiles because of instability in mouse liver microsome. To improve metabolic stability, various analogues were prepared with substituents on aromatic ring of cap group and various chain lengths between the cap group and δ-lactam core. The newly prepared analogues showed moderate to potent in vitro activities. Among them six compounds (8a, 8e, 8j, 8n, 8t, and 8v) were evaluated on mouse liver microsome assay and it turned out that the microsomal stabilities were dependent on lipophilicity and the number of the rotatable bonds. Finally, the animal pharmacokinetic profiles of 8e displayed improving oral exposure and oral bioavailability.     

Regulation of biosynthesis and intracellular localization of rice and tobacco homologues of nucleosome assembly protein 1

The nucleosome assembly protein 1 (NAP1) is considered to be a conserved histone chaperone, facilitating the assembly of nucleosomes in all eukaryotes. However, studies in yeast and animal cells also indicated that NAP1 proteins have diverse functions likely independent of nucleosome-assembly activity. Here, we describe the isolation and characterization of cDNAs encoding NAP1-like proteins from the monocotyledon rice ( Oryza sativa L.) and the dicotyledon tobacco ( Nicotiana tabacum L.). Northern-blot analysis demonstrated that the two rice NAP1-like genes are predominantly expressed in stem tissues such as root and shoot apical meristems as well as in young flowers. During the cell cycle, all four tobacco NAP1-like genes are highly expressed, with one of them showing a slightly increased expression at the G1/S transition. These results are consistent with a role for plant NAP1-like proteins in cell division. In vitro binding assays revealed that different NAP1-like proteins bind, with distinct relative binding strengths, to different classes of histone. Intracellular localization analyses showed that some NAP1-like proteins could be targeted into the nucleus whereas others are exclusively cytoplasm-localized. It is thus likely that different plant NAP1-like proteins have distinct functions in vivo. Plant NAP1-like proteins were observed to concentrate around the metaphase plate and in the phragmoplast, suggesting a role in mitotic events and cytokinesis.     

Characteristics and application of S1–P1 nucleases in biotechnology and medicine

3′–nucleases/nucleotidases of the S1–P1 family (EC 3.1.30.1) are single–strand–specific or non-specific zinc–dependent phosphoesterases present in plants, fungi, protozoan parasites, and in some bacteria. They participate in a wide variety of biological processes and their current biotechnological applications rely on their single–strand preference, nucleotide non-specificity, a broad range of catalytic conditions and high stability. We summarize the present and potential utilization of these enzymes in biotechnology and medicine in the context of their biochemical and structure–function properties. Explanation of unanswered questions for bacterial and trypanosomatid representatives could facilitate development of emerging applications in medicine.     

The clastogenic and mutagenic effects of ascorbigen and 1′-methylascorbigen

Ascorbingen, which occurs naturally in the human diet, and a synthetic analogue (1′-methylascorbigen), were assayed for cytotoxic and clastogenic activities in a SV₄₀-transformed Indian Muntjac cell line (SVM), and for mutagenic activity in the Ames test using Salmonella typhimurium strains TA98 and TA100. Ascorbigen had no effect upon the clonal survival of SVM at concentrations below 0.21 mg/ml and did not induce either chromosome aberrations or sister-chromatid exchanges (SCEs) at any concentration tested up to the maximum compatible with the assay conditions; nor did it induce mutations in either Salmonella strain. In contrast, 1′-methylascorbigen was an order of magnitude more cytotoxic, demonstrating a D_q of 0.03 mg/ml, and whilst it too was not found to induce chromosome aberrations it did induce SCEs in SVM (although only at higly cytotoxic doses) and mutations in the Ames test.     

Affinity of different α1-agonists and antagonists for the α1-adrenoceptors of rabbit and rat liver membranes

In membranes prepared from rabbit liver, competition with [³H] prazosin by different α₁-agonists and antagonists revealed different affinities in comparison to the results obtained on rat liver membranes, and showed a good correlation with the affinity of the same compounds for the cloned α_1c-adrenoceptor subtype. The potencies observed on rat liver membranes were well correlated with the affinity observed for the cloned α_1b-adrenoceptors. These results confirm that rabbit and rat liver membranes preparations can be utilized to evaluate the affinity of compounds for these α₁-adrenergic subtypes.     

Receptor-mediated nonproteolytic activation of prorenin and induction of TGF-β1 and PAI-1 expression in renal mesangial cells

While elevated plasma prorenin levels are commonly found in diabetic patients and correlate with diabetic nephropathy, the pathological role of prorenin, if any, remains unclear. Prorenin binding to the (pro)renin receptor [(p)RR] unmasks prorenin catalytic activity. We asked whether elevated prorenin could be activated at the site of renal mesangial cells (MCs) through receptor binding without being proteolytically converted to renin. Recombinant inactive rat prorenin and a mutant prorenin that is noncleavable, i.e., cannot be activated proteolytically, are produced in 293 cells. After MCs were incubated with 10(-7) M native or mutant prorenin for 6 h, cultured supernatant acquired the ability to generate angiotensin I (ANG I) from angiotensinogen, indicating both prorenins were activated. Small interfering RNA (siRNA) against the (p)RR blocked their activation. Furthermore, either native or mutant rat prorenin at 10(-7) M alone similarly and significantly induced transforming growth factor-β(1), plasminogen activator inhibitor-1 (PAI-1), and fibronectin mRNA expression, and these effects were blocked by (p)RR siRNA, but not by the ANG II receptor antagonist, saralasin. When angiotensinogen was also added to cultured MCs with inactive native or mutant prorenin, PAI-1 and fibronectin were further increased significantly compared with prorenin or mutant prorenin alone. This effect was blocked partially by treatment with (p)RR siRNA or saralasin. We conclude that prorenin binds the (p)RR on renal MCs and is activated nonproteolytically. This activation leads to increased expression of PAI-1 and transforming growth factor-β(1) via ANG II-independent and ANG II-dependent mechanisms. These data provide a mechanism by which elevated prorenin levels in diabetes may play a role in the development of diabetic nephropathy.