Preparation and properties of clickable amino analogues of the duocarmycins: factors that affect the efficiency of their fluorescent labelling of DNA

One-pot and metal-free synthesis of 3-arylated-4-nitrophenols via polyfunctionalized cyclohexanones from β-nitrostyrenes

β-Nitrostyrenes underwent a Diels-Alder reaction with Danishefsky's diene to afford cyclohexenes together with the corresponding hydrolyzed products, 3-arylated-5-methoxy-4-nitrocyclohexanones. When the reaction was conducted in the presence of water, the cyclohexenes were efficiently hydrolyzed into cyclohexanones. Subsequent aromatization by heating the cyclohexanone with a catalytic amount of iodine in dimethyl sulfoxide gave 3-arylated-4-nitrophenols. The reaction of nitrostyrenes with Danishefsky's diene could be conducted in one pot to directly afford the corresponding nitrophenols. Moreover, a heteroaryl group, e.g., a thienyl group could be introduced into the nitrophenol framework.

Design, synthesis, nuclear localization, and biological activity of a fluorescent duocarmycin analog, HxTfA

HxTfA 4 is a fluorescent analog of a potent cytotoxic and antimalarial agent, TfA 3, which is currently being investigated for the development of an antimalarial vaccine, PlasProtect®. HxTfA contains a p-anisylbenzimidazole or Hx moiety, which is endowed with a blue emission upon excitation at 318 nm; thus enabling it to be used as a surrogate for probing the cellular fate of TfA using confocal microscopy, and addressing the question of nuclear localization. HxTfA exhibits similar selectivity to TfA for A-tract sequences of DNA, alkylating adenine-N3, albeit at 10-fold higher concentrations. It also possesses in vitro cytotoxicity against A549 human lung carcinoma cells and Plasmodium falciparum. Confocal microscopy studies showed for the first time that HxTfA, and by inference TfA, entered A549 cells and localized in the nucleus to exert its biological activity. At biologically relevant concentrations, HxTfA elicits DNA damage response as evidenced by a marked increase in the levels of γH2AX observed by confocal microscopy and immunoblotting studies, and ultimately induces apoptosis.

Influence of a Basic Side Chain on the Properties of Hypoxia-Selective Nitro Analogues of the Duocarmycins: Demonstration of Substantial Anticancer Activity in Combination with Irradiation or Chemotherapy

A new series of nitro analogues of the duocarmycins was prepared and evaluated for hypoxia-selective anticancer activity. The compounds incorporate 13 different amine-containing side chains designed to bind in the minor groove of DNA while spanning a wide range of base strength from pK_a 9.64 to 5.24. The most favorable in vitro properties were associated with strongly basic side chains, but the greatest in vivo antitumor activity was found for compounds containing a weakly basic morpholine. This applies to single-agent activity and for activity in combination with irradiation or chemotherapy (gemcitabine or docetaxel). In combination with a single dose of γ irradiation 50 at 42 μmol/kg eliminated detectable clonogens in some SiHa cervical carcinoma xenografts, and in combination with gemcitabine using a well-tolerated multidose schedule, the same compound caused regression of all treated A2780 ovarian tumor xenografts. In the latter experiment, three of seven animals receiving the combination treatment were completely tumor free at day 100.

Flow cytometry detection of vitamin D receptor changes during vitamin D treatment in Crohn's disease

Crohn's disease (CD) is a chronic inflammatory disease associated with a dysregulated T cell response towards intestinal microflora. Vitamin D has immune modulatory effects on T cells through the nuclear vitamin D receptor (VDR) in vitro. It is unclear how oral vitamin D treatment affects VDR expression. The aim of this study was to establish a flow cytometry protocol, including nuclear and cytoplasmic VDR expression, and to investigate the effects of vitamin D treatment on T cell VDR expression in CD patients. The flow cytometry protocol for VDR staining was developed using the human acute monocytic leukaemia cell line (THP-1). The protocol was evaluated in anti-CD3/CD28-stimulated peripheral blood mononuclear cells (PBMCs) from vitamin D3- (n = 9) and placebo-treated (n = 9) CD patients. Anti-VDR-stained PBMCs were examined by flow cytometry, and their cytokine production was determined by cytokine bead array. VDR, CYP27B1 and RXRα mRNA expression levels in CD4(+) T cells were measured by quantitative reverse transcriptase polymerase chain reaction. The flow cytometry protocol enabled detection of cytoplasmic and nuclear VDR expression. The results were confirmed by confocal microscopy and supported by correlation with VDR mRNA expression. VDR expression in CD4(+) T cells increased following stimulation. This VDR up-regulation was inhibited with 30% by vitamin D treatment compared to placebo in CD patients (P = 0027). VDR expression was correlated with in-vitro interferon-γ production in stimulated PBMCs (P = 0.01). Flow cytometry is a useful method with which to measure intracellular VDR expression. Vitamin D treatment in CD patients reduces T cell receptor-mediated VDR up-regulation.