ZB716, a Steroidal Selective Estrogen Receptor Degrader (SERD), is Orally Efficacious in Blocking Tumor Growth in Mouse Xenograft Models.

Advances in oral SERDs development so far have been confined to nonsteroidal molecules such as those containing a cinnamic acid moiety, which are in earlystage clinical evaluation. ZB716 was previously reported as an orally bioavailable SERD structurally analogous to fulvestrant. In this study, we examined the binding details of ZB716 to the estrogen receptor alpha (ERα) by computer modeling to reveal its interactions with the ligand binding domain as a steroidal molecule. We also found that ZB716 modulates ERα-coregulator interactions in nearly identical manner to fulvestrant. The ability of ZB716 to inhibit cell growth and downregulate ER expression in endocrine resistant, ERα mutant breast cancer cells was demonstrated. Moreover, in both the MCF-7 xenograft and a patient derived xenograft model, orally administered ZB716 showed superior efficacy in blocking tumor growth when compared to fulvestrant. Importantly, such enhanced efficacy of ZB716 was shown to be attributable to its markedly higher bioavailability, as evidenced in the final plasma and tumor tissue concentrations of ZB716 in mice where drug concentrations were found significantly higher than in the fulvestrant treatment group

HDAC 阻害剤は Diethylstilbestrol による性腺刺激ホルモン細胞からのプロラクチン細胞への分化転換を抑制する

Diethylstilbestrol (DES), an estrogen agonist, increases prolactin (PRL) cells through transdifferentiation of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) cells to PRL cells as well as proliferation of PRL cells in adult male mouse pituitary. Since hyperacetylation of histone H3 is implicated in the regulation of activation of various genes, we examined the effect of DES on the state of histone H3 acetylation. DES significantly reduced the immunohistochemical signal for acetylated histone H3 at lysine 9 (H3K9ac) in PRL, LH and FSH cells, but not for H3K18ac or H3K23ac. DES-treated mice were injected intraperitoneally with HDAC inhibitors (HDACi), sodium phenylbutyrate (NaPB) or valproic acid (VPA), to mimic the acetylation level of histone H3. As expected, HDACi treatment restored the level of H3K9ac expression in these cells, and also inhibited DES-induced increase in PRL cells. Furthermore, NaPB and VPA also abrogated the effects of DES on the population density of both LH and FSH cells. Similarly, the numbers of proliferating and apoptotic cells in the pituitary in NaPB- or VPA-treated mice were comparable to those of the control mice. Considered together, these results indicated that the acetylation level of histone H3 plays an important role in DES-induced transdifferentiation of LH to PRL cells as well as proliferation of PRL cells.長崎大学学位論文 学位記番号:博(医歯薬)甲第1128号 学位授与年月日:平成31年3月20日Author: Nandar Tun, Yasuaki Shibata, Myat Thu Soe, Myo Win Htun, Takehiko KojiCitation: Histochemistry and Cell Biology, 151(4), pp.291-303; 2018Nagasaki University (長崎大学)課程博

The in vitro Effects of Pentamidine Isethionate on Coagulation and Fibrinolysis

Pentamidine is bis-oxybenzamidine-based antiprotozoal drug. The parenteral use of pentamidine appears to affect the processes of blood coagulation and/or fibrinolysis resulting in rare but potentially life-threatening blood clot formation. Pentamidine was also found to cause disseminated intravascular coagulation syndrome. To investigate the potential underlying molecular mechanism(s) of pentamidine’s effects on coagulation and fibrinolysis, we studied its effects on clotting times in normal and deficient human plasmas. Using normal plasma, pentamidine isethionate doubled the activated partial thromboplastin time at 27.5 µM, doubled the prothrombin time at 45.7 µM, and weakly doubled the thrombin time at 158.17 µM. Using plasmas deficient of factors VIIa, IXa, XIa, or XIIa, the concentrations to double the activated partial thromboplastin time were similar to that obtained using normal plasma. Pentamidine also inhibited plasmin-mediated clot lysis with half-maximal inhibitory concentration (IC50) value of ~3.6 µM. Chromogenic substrate hydrolysis assays indicated that pentamidine inhibits factor Xa and plasmin with IC50 values of 10.4 µM and 8.4 µM, respectively. Interestingly, it did not significantly inhibit thrombin, factor XIa, factor XIIIa, neutrophil elastase, or chymotrypsin at the highest concentrations tested. Michaelis-Menten kinetics and molecular modeling studies revealed that pentamidine inhibits factor Xa and plasmin in a competitive fashion. Overall, this study provides quantitative mechanistic insights into the in vitro effects of pentamidine isethionate on coagulation and fibrinolysis via the disruption of the proteolytic activity of factor Xa and plasmin

Histone Deacetylase Inhibitors in Clinical Studies as Templates for New Anticancer Agents

Histone dacetylases (HDACs) are a group of enzymes that remove acetyl groups from histones and regulate expression of tumor suppressor genes. They are implicated in many human diseases, especially cancer, making them a promising therapeutic target for treatment of the latter by developing a wide variety of inhibitors. HDAC inhibitors interfere with HDAC activity and regulate biological events, such as cell cycle, differentiation and apoptosis in cancer cells. As a result, HDAC inhibitor-based therapies have gained much attention for cancer treatment. To date, the FDA has approved three HDAC inhibitors for cutaneous/peripheral T-cell lymphoma and many more HDAC inhibitors are in different stages of clinical development for the treatment of hematological malignancies as well as solid tumors. In the intensifying efforts to discover new, hopefully more therapeutically efficacious HDAC inhibitors, molecular modeling-based rational drug design has played an important role in identifying potential inhibitors that vary in molecular structures and properties. In this review, we summarize four major structural classes of HDAC inhibitors that are in clinical trials and different computer modeling tools available for their structural modifications as a guide to discover additional HDAC inhibitors with greater therapeutic utility

Alkanediamide-Linked Bisbenzamidines are Promising Antiparasitic Agents

A series of 15 alkanediamide-linked bisbenzamidines and related analogs was synthesized and tested in vitro against two Trypanosoma brucei (T.b.) subspecies: T.b. brucei and T.b. rhodesiense, Trypanosoma cruzi, Leishmania donovani and two Plasmodium falciparum subspecies: A chloroquine-sensitive strain (NF54) and a chloroquine-resistant strain (K1). The in vitro cytotoxicity was determined against rat myoblast cells (L6). Seven compounds (5, 6, 10, 11, 12, 14, 15) showed high potency against both strains of T. brucei and P. falciparum with the inhibitory concentrations for 50% (IC50) in the nanomolar range (IC50 = 1-96 nM). None of the tested derivatives was significantly active against T. cruzi or L. donovani. Three of the more potent compounds (5, 6, 11) were evaluated in vivo in mice infected with the drug-sensitive (Lab 110 EATRO and KETRI 2002) or drug-resistant (KETRI 2538 and KETRI 1992) clinical isolates of T. brucei. Compounds 5 and 6 were highly effective in curing mice infected with the drug-sensitive strains, including a drug-resistant strain KETRI 2538, but were ineffective against KETRI 1992. Thermal melting of DNA and molecular modeling studies indicate AT-rich DNA sequences as possible binding sites for these compounds. Several of the tested compounds are suitable leads for the development of improved antiparasitic agents

Characterization of kinesin switch I mutations that cause hereditary spastic paraplegia

<div><p>Kif5A is a neuronally-enriched isoform of the Kinesin-1 family of cellular transport motors. 23 separate mutations in the motor domain of Kif5A have been identified in patients with the complicated form of hereditary spastic paraplegia (HSP). We performed in vitro assays on dimeric recombinant Kif5A with HSP-causing mutations in the Switch I domain, which participates in the coordination and hydrolysis of ATP by kinesin. We observed a variety of significantly reduced catalytic and mechanical activities as a result of each mutation, with the shared phenotype from each that motility was significantly reduced. Substitution of Mn²⁺ for Mg²⁺ in our reaction buffers provides a dose-dependent rescue in both the catalytic and ensemble mechanical properties of the S203C mutant. This work provides mechanistic insight into the cause of HSP in patients with these mutations and points to future experiments to further dissect the root cause of this disease.</p></div

Modification and Biological Evaluation of Thiazole Derivatives as Novel Inhibitors of Metastatic Cancer Cell Migration and Invasion

Fascin has recently emerged as a potential therapeutic target, as its expression in cancer cells is closely associated with tumor progression and metastasis. Following the initial discovery of a series of thiazole derivatives that demonstrated potent antimigration and antiinvasion activities via possible inhibition of fascin function, we report here the design and synthesis of 63 new thiazole derivatives by further structural modifications in search of more potent fascin inhibitors. The 5 series of analogues with longer alkyl chain substitutions on the thiazole nitrogen exhibited greater antimigration activities than those with other structural motifs. The most potent analogue, 5p, inhibited 50% of cell migration at 24 nM. Moreover, the thiazole analogues showed strong antiangiogenesis activity, blocking new blood vessel formation in a chicken embryo membrane assay. Finally, a functional study was conducted to investigate the mechanism of action via interaction with the F-actin bundling protein fascin

Effect of divalent cation on S203C microtubule gliding velocity.

<p>A) Microtubule gliding velocity of the S203C mutant in buffers with the divalent cations shown. The asterisk indicates that the velocity in Mn²⁺ is significantly greater than the velocity in Mg²⁺ (p<0.01), although still significantly lower than wild type in Mg²⁺ (p<0.01). Note the log scale of the Y-axis. B) Microtubule gliding velocity of the S203C mutant that was purified in the presence of Mg²⁺ (Mg-S203C) and Mn²⁺ (Mn-S203C). The single asterisk indicates that the velocity of Mg-S203C in Mn²⁺ is significantly greater than in Mg²⁺ (p<0.01), while the double asterisk indicates that the velocity of Mn-S203C in Mn²⁺ is significantly greater than in Mg²⁺ (p<0.01), and also significantly greater than the velocity of Mg-S203C in Mn²⁺ (p<0.05). C) Histograms of the data for S203C mutants in the conditions indicated. A similar number of microtubules (n = 90–110) were analyzed in each condition.</p