JAK/STAT pathway inhibition overcomes IL7-induced glucocorticoid resistance in a subset of human T-cell acute lymphoblastic leukemias.

While outcomes for children with T-cell acute lymphoblastic leukemia (T-ALL) have improved dramatically, survival rates for patients with relapsed/refractory disease remain dismal. Prior studies indicate that glucocorticoid (GC) resistance is more common than resistance to other chemotherapies at relapse. In addition, failure to clear peripheral blasts during a prednisone prophase correlates with an elevated risk of relapse in newly diagnosed patients. Here we show that intrinsic GC resistance is present at diagnosis in early thymic precursor (ETP) T-ALLs as well as in a subset of non-ETP T-ALLs. GC-resistant non-ETP T-ALLs are characterized by strong induction of JAK/STAT signaling in response to interleukin-7 (IL7) stimulation. Removing IL7 or inhibiting JAK/STAT signaling sensitizes these T-ALLs, and a subset of ETP T-ALLs, to GCs. The combination of the GC dexamethasone and the JAK1/2 inhibitor ruxolitinib altered the balance between pro- and anti-apoptotic factors in samples with IL7-dependent GC resistance, but not in samples with IL7-independent GC resistance. Together, these data suggest that the addition of ruxolitinib or other inhibitors of IL7 receptor/JAK/STAT signaling may enhance the efficacy of GCs in a biologically defined subset of T-ALL.

Redox reactivity of guanyl radicals in plasmid DNA.

PURPOSE: It has been previously argued that gamma-irradiation of plasmid DNA in the presence of thiocyanate ions produces products recognized by the E. coli base excision-repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG), and there that derive from an intermediate guanyl radical species. The wish was to characterize the reactivity of this intermediate with reducing agents. MATERIALS AND METHODS: Aqueous solutions of plasmid DNA containing either bromide or thiocyanate (10(-3) to 10(-1) mol dm(-3)) and also one of six other additives (azide, ferrocyanide, iodide, nitrite, promethazine, tryptophan, 10(-7) to 10(-3) mol dm(-3)) were subjected to 137Cs gamma-irradiation (662 keV). After irradiation, the plasmid was incubated with FPG. Strand break yields before and after incubation were determined by agarose gel electrophoresis under neutral conditions. RESULTS: The very high yields of FPG-sensitive sites in the presence of SCN- or Br- decreased significantly with increasing concentrations of all of the six additives, with promethazine and tryptophan being the most efficient additives, and azide and iodide the least. CONCLUSIONS: From the results it is possible to estimate values of the rate constants for the reduction of the DNA guanyl radical (5 x 10(5), 2 x 10(5), 10(7) and 10(7) dm3 mol(-1) s(-1) for ferrocyanide, nitrite, promethazine and tryptophan respectively).

Enhancement of intestinal model compound transport by DS-1, a modified Quillaja saponin.

DS-1, a modified Quillaja saponin, has recently been shown to promote the absorption of insulin and aminoglycoside antibiotics via the ocular and nasal route. The purpose of this study is to investigate the effect of DS-1 on intestinal permeability, the mechanism of its action, and reversibility of the effect. The permeation-enhancing activity of DS-1 was evaluated in cultured monolayers of the Caco-2 intestinal epithelial cells by examining its effect on the transepithelial electric resistance (TEER) and on transport of mannitol and a model D-decapeptide. Mucosal addition of DS-1 promptly reduced the TEER of the Caco-2 monolayers, and a propensity of recovery of the TEER was observed upon its removal. DS-1 added at 0.01-0.1% (w/v) increased the transports of both mannitol and D-decapeptide in a dose-dependent manner; a relatively "flat" concentration-dependence was seen at 0.1-0.2%. Visualization studies conducted by confocal laser scanning microscopy (CLSM) seem to suggest that DS-1 enhances the Caco-2 permeability mainly via a transcellular route. Histological examination failed to reveal noticeable morphological alterations in the cell monolayers pretreated with DS-1. The integrity of the Caco-2 monolayers, as assessed by their permeability to mannitol, was found to be recoverable following the mucosal pretreatment of DS-1. These results suggest that DS-1 is an efficacious intestinal permeation-enhancing agent with low adverse effect on the epithelial viability and barrier function.

In vitro and in vivo evaluation of effects of sodium caprate on enteral peptide absorption and on mucosal morphology.

Sodium salts of medium-chain fatty acids, sodium caprate (C10) in particular, have been used as absorption-enhancing agents to promote transmucosal drug absorption. In this study, we conducted both in vitro and in vivo experiments to investigate the effects of C10 on intestinal permeabilities and mucosal morphology. Mucosal addition of C10 (13-25 mM) reduced the transepithelial electric resistance (TEER) of cultured monolayers of the human intestinal cell line Caco-2 by 40-65% and, upon removal of C10, a marked tendency of TEER recovery was recorded. C10 added mucosally at 13-50 mM increased the transports of mannitol and polyethylene glycol (PEG) 900 across Caco-2 in a dose-dependent manner. In contrast, the transport of a model D-decapeptide was maximally enhanced with 20-25 mM C10. No noticeable morphological alteration of the Caco-2 monolayers was observed after a 1-h mucosal pretreatment with C10. Co-delivery with C10 (0.05-0.5 mmol/kg) into the rat terminal ileum increased the D-decapeptide bioavailability (BA) dose-dependently. With 0.5 mmol/kg C10 co-administered, D-decapeptide percent BA was elevated from 2 to 11%. Following a 1-h incubation with 0.5 mmol/kg C10 (in liquid or powder form) non-invasively delivered into the rectal lumen, no signs of histological change in the rectal mucosa were detected. These results demonstrate that C10 can promote intestinal absorption of a small peptide without causing detrimental alterations of the intestinal mucosa. C10 thus seems to be a good candidate as an enhancing agent for improving the oral BA of small therapeutic peptides.