Rigidity versus flexibility: is this an issue in S1 (sigma-1) receptor ligand affinity and activity?

A set of stereoisomeric 2,5-diazabicyclo[2.2.2]octanes 14 and 15 was prepared in a chiral-pool synthesis starting from (S)- or (R)-aspartate. The key step in the synthesis was a Dieckmann-analogous cyclization of (dioxopiperazinyl)acetates 8, which involved trapping uf the intermediate hemiketal anion with Me3SiCl. The \u3c31 affinity was tested using membrane preparations from animal (guinea pig) and human origin. The binding of bicyclic compounds was analyzed by molecular dynamics simulations based on a 3D homology model of the \u3c31 receptor. The good correlation between Ki values observed in the \u3c31 assays and calculated free binding energy, coupled with the identification of four crucial ligand/receptor interactions allowed the formulation of structure affinity relationships. In an in vitro antitumor assay with seven human tumor cell lines, the bicyclic compounds inhibited selectively the growth of the cell line A427, which is due to induction of apoptosis. In this assay, the compounds behave like the known \u3c31 receptor antagonist haloperidol

Genome organization and chromatin analysis identify transcriptional downregulation of insulin-like growth factor signaling as a hallmark of aging in developing B cells.

BACKGROUND: Aging is characterized by loss of function of the adaptive immune system, but the underlying causes are poorly understood. To assess the molecular effects of aging on B cell development, we profiled gene expression and chromatin features genome-wide, including histone modifications and chromosome conformation, in bone marrow pro-B and pre-B cells from young and aged mice. RESULTS: Our analysis reveals that the expression levels of most genes are generally preserved in B cell precursors isolated from aged compared with young mice. Nonetheless, age-specific expression changes are observed at numerous genes, including microRNA encoding genes. Importantly, these changes are underpinned by multi-layered alterations in chromatin structure, including chromatin accessibility, histone modifications, long-range promoter interactions, and nuclear compartmentalization. Previous work has shown that differentiation is linked to changes in promoter-regulatory element interactions. We find that aging in B cell precursors is accompanied by rewiring of such interactions. We identify transcriptional downregulation of components of the insulin-like growth factor signaling pathway, in particular downregulation of Irs1 and upregulation of Let-7 microRNA expression, as a signature of the aged phenotype. These changes in expression are associated with specific alterations in H3K27me3 occupancy, suggesting that Polycomb-mediated repression plays a role in precursor B cell aging. CONCLUSIONS: Changes in chromatin and 3D genome organization play an important role in shaping the altered gene expression profile of aged precursor B cells. Components of the insulin-like growth factor signaling pathways are key targets of epigenetic regulation in aging in bone marrow B cell precursors

Evaluation for Synergistic Effects by Combinations of Photodynamic Therapy (PDT) with Temoporfin (mTHPC) and Pt(II) Complexes Carboplatin, Cisplatin or Oxaliplatin in a Set of Five Human Cancer Cell Lines

The platinum(II) complexes carboplatin (CBDCA), cisplatin (CDDP) and oxaliplatin (1-OHP) are used as anticancer drugs in a large number of tumour chemotherapy regimens. Many attempts have been made to combine Pt(II)-based chemotherapy with alternative treatment strategies. One such alternative anticancer approach is known as photodynamic therapy (PDT), where a non-toxic photosensitizer (PS) produces oxidative stress via the formation of reactive oxygen species (ROS) after local illumination of the affected tissue. A very promising PS is 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (mTHPC, Temoporfin), which is approved for the treatment of head and neck cancer in Europe. In the present study, a combination of mTHPC-mediated PDT and either CBDCA, CDDP, or 1-OHP was applied to five human cancer cell lines from different tumour origins. Cytotoxicity was determined by the MTT assay and synergistic effects on cytotoxicity were evaluated by calculation of Combination Indices (CI). Synergy was identified in some of the combinations, for example, with 1-OHP in three of the tested cell lines but antagonism was also observed for a number of combinations in certain cell lines. In cases of synergy, elevated ROS levels were observed after combination but apoptosis induction was not necessarily increased compared to a treatment with a single compound. Cell cycle analysis revealed a formation of apoptotic subG1 populations and S phase as well as G2/M phase arrests after combination. In conclusion, pre-treatment with mTHPC-PDT has the potential to sensitize some types of tumour cells towards Pt(II) complexes, in particular 1-OHP but synergy is highly dependent on the type of cancer

EXAFS, DFT, light-induced nucleobase binding, and cytotoxicity of the photoactive complex cis-[Ru(bpy)2(CO)Cl]+

The aqueous photochemistry of cis-[Ru(bpy)2(CO)Cl]+ (1) was investigated at 310 K and under visible light (white) irradiation by NMR and ESI-HR-MS. Complex 1 releases a Cl ligand, coordinates a solvent molecule, and forms the complex cis-[Ru(bpy)2(CO)(H2O)]2+ (2). Also, irradiation experiments were performed in the presence of the nucleobase derivatives 9-ethylguanine (9-EtG) and 9-ethyladenine (9-EtA). Formation of Ru-9-EtG adducts was observed after 3 h irradiation by NMR and HR-MS, while only very small amounts of a Ru-9-EtA adduct could be detected by HR-MS. Solution structural data were obtained by X-ray absorption spectroscopy (XAS) for both 1 and 2. EXAFS gave a Ru−Cl distance of 2.416(7) Å for 1 and a Ru−OH2O distance of 2.102(6) Å for 2. DFT and TDDFT were employed to study the photophysical and photochemical properties of 1. Calculations show that dissociative metal-centered states can be related to the light-induced release of a Cl ligand and subsequent coordination of a solvent molecule. The compound showed no antiproliferative activity in three human carcinoma cell lines (lung, bladder, pancreas) under the testing conditions, either with or without irradiation with UV light

(1,2-Diaryl-1,2-ethylenediamine)platinum(II) complexes with sulfato and 3-sulfopropionato leaving groups: investigations with different types of coordination in the solid state, in solution and reactions with nucleophiles

The syntheses, solid state and soln. chem., and the in vitro cytotoxic activities of H2O sol. (1,2-diaryl-1,2-ethylenediamine)platinum(II) complexes, having either the sulfato or the novel sulfopropionato anionic leaving group, are described. The compds. were prepd. by allowing the (1,2-diaryl-1,2-ethylenediamine)diiodoplatinum(II) complexes and either Ag2SO4 or Ag sulfopropionate to react in H2O. IR studies of the complexes in the solid state indicate that the prepn. are mixts. of Pt species, whereby the anionic leaving groups show varying forms of Pt coordination. These compns. vary depending on the procedure used to isolate the Pt complexes. The aq. soln. chem. was studied by a reversed-phase HPLC assay. The results of these studies show several Pt species in soln. From the column retention properties of the species and their behavior to changes in pH, these soln. components are various monomers and oligomers of the parent Pt complex. These results are in agreement with previous 195Pt and 15N NMR studies from other diaminePt(II) complexes. The type of arom. substitution has an influence on the qual. compn. of the aq. Pt species; an addnl. Pt species is obsd. in aq. solns. of Pt complexes possessing an ortho phenol group compared to the complexes possessing a para F group. Aq. reactions of the Pt complexes with Cl- indicate that the sulfopropionato ligand is more stable-bound than the SO42- ligand; results from cell culture cytotoxicity tests show little difference between the cytotoxic activities of the complexes possessing a sulfato or a sulfopropionato leaving group

The Effect of Glutathione Peroxidase-1 Knockout on Anticancer Drug Sensitivities and Reactive Oxygen Species in Haploid HAP-1 Cells

The role of glutathione peroxidases (GPx) in cancer and their influence on tumor prognosisand the development of anticancer drug resistance has been extensively and controversially discussed.The aim of this study was to evaluate the influence of GPx1 expression on anticancer drug cytotoxicity.For this purpose, a GPx1 knockout of the near-haploid human cancer cell line HAP-1 was generatedand compared to the native cell line with regards to morphology, growth and metabolic rates,and oxidative stress defenses. Furthermore, the IC50values of two peroxides and 16 widely usedanticancer drugs were determined in both cell lines. Here we report that the knockout of GPx1 in HAP-1cells has no significant effect on cell size, viability, growth and metabolic rates. Significant increasesin the cytotoxic potency of hydrogen peroxide andtert-butylhydroperoxide, the anticancer drugscisplatin and carboplatin as well as the alkylating agents lomustine and temozolomide were found.While a concentration dependent increases in intracellular reactive oxygen species (ROS) levelswere observed for both HAP-1 cell lines treated with either cisplatin, lomustine or temozolamide,no significant enhancement in ROS levels was observed in the GPx1 knockout compared to the nativecell line except at the highest concentration of temozolamide. On the other hand, a ca. 50% decreasein glutathione levels was noted in the GPx1 knockout relative to the native line, suggesting thatfactors other than ROS levels alone play a role in the increased cytotoxic activity of these drugs in theGPx1 knockout cells

Aqueous chemistry of mixed-amine cis- and transplatin analogues. Intramolecular preference for a kinetic six-membered ring over a thermodynamic five-membered ring ortho-platination product

A series of mixed-amine cis- and trans-platin analogs, contg. benzylamine and 2-phenylethylamine functionalities, were synthesized and the aq. soln. chem. investigated. The cis- and trans-Pt(NH3)LCl2 (I; L = (1,2-bis(4-methoxyphenyl)ethylamine (MREA), 2-(4-methoxyphenyl)-1-phenylethylamine (MPPEA), bis(4-methoxyphenyl)methylamine (MPMA)) were synthesized in >98% isomeric purity. With the aim of investigating the pharmacoactivation of this class of compds., a reversed-phase HPLC assay was developed for detg. the rates of Pt-Cl hydrolysis of the cis-configured isomers. The precolumn addn. of KBr to the reaction solns. trapped the aquachloro- and diaquaplatinum hydrolysis products as their bromo adducts. The sepns. of dichloro-, bromochloro-, and dibromoplatinum complexes allowed the quantification of their time-dependent concns., and the hydrolysis rate consts. for cis-I could be detd. Following Pt-Cl hydrolysis, an intramol. ortho-platination occurred with I. Proton NMR studies showed that, for the trans-I (L = MPEA, MPPEA), the kinetically favored, 6-membered ring cycloplatinated products were formed specifically over the thermodn., 5-membered ring ones. For cis-I (L = MPEA), the kinetic product was formed selectively. The 6-membered cycloplatinated ring could be converted into the 5-membered, thermodn. favored one by heating in dil. KCl. The implications of these novel findings are discussed from both mechanistic chem. and pharmacol. points of view