Overcoming ABCG2-mediated drug resistance with imidazo-[1,2-b]-pyridazine-based Pim1 kinase inhibitors

Purpose Multidrug efflux pumps such as ABCG2 confer drug resistance to a number of cancer types, leading to poor prognosis and outcome. To date, the strategy of directly inhibiting multidrug efflux pumps in order to overcome drug resistance in cancer has been unsuccessful. An alternative strategy is to target proteins involved in the regulation of multidrug efflux pump activity or expression. Pim1 kinase has been demonstrated to phosphorylate ABCG2, promote its oligomerisation and contribute to its ability to confer drug resistance. Methods In the present manuscript, imidazo-pyridazine-based inhibitors of Pim1 were examined for their ability to overcome ABCG2-mediated drug resistance. Drug efficacy was measured as a cytotoxic response or an effect on transport by ABCG2. Protein expression patterns were assessed using western immuno-blotting. Results The two Pim1 inhibitors increased the potency of flavopiridol, mitoxantrone, topotecan and doxorubicin, specifically in ABCG2-expressing cells. This effect was associated with an increase in the cellular accumulation of [3H]-mitoxantrone, suggesting direct impairment of the transporter. However, prolonged pre-incubation with the studied inhibitors greatly enhanced the effect on mitoxantrone accumulation. The inhibitors caused a significant time-dependent reduction in the expression of ABCG2 in the resistant cells, an effect that would improve drug efficacy. Conclusion Consequently, it appears that the Pim1 inhibitors display a dual-mode effect on ABCG2-expressing cancer cells. This may provide a powerful new strategy in overcoming drug resistance by targeting proteins that regulate expression of efflux pumps

IL-27R deficiency delays the onset of colitis and protects from helminth-induced pathology in a model of chronic IBD

Members of the IL-6/IL-12 cytokine family play central roles in Crohn's disease. The present findings demonstrate that IL-27, a close relative of IL-12 and IL-23, can promote the onset of colitis in mice. We report that, compared with IL-10-deficient animals, which succumb to chronic intestinal disease at 3-6 months of age, mice lacking both IL-10 and the IL-27R (IL-27R/WSX-1) exhibit delayed pathology and prolonged survival (>1 year). Moreover, unlike highly susceptible IL-10-deficient counterparts, they were able to clear infection with Trichuris muris, a colon-dwelling nematode. In both models of intestinal inflammation, improved clinical outcome was associated with reduced inflammation and profound attenuation of Th1 responses and, consistent with these in vivo findings, we confirmed that during in vitro differentiation, IL-27 directly promotes CD4+ T cell IFN-γ production through effects on Tbet, a key Th1 transcription factor. We also found that its ability to suppress Th2 responses, which was clearly evident in helminth-infected IL-10−/−IL-27R−/− mice, was largely Tbet independent. Taken together, these studies demonstrate that, in the absence of IL-10, IL-27 can promote Th1-type and suppress Th2-type intestinal inflammation but, ultimately, is not required for the development of inflammatory bowel disease

Statistical power of latent growth curve models to detect quadratic growth

Latent curve models (LCMs) have been used extensively to analyze longitudinal data. However, little is known about the power of LCMs to detect nonlinear trends when they are present in the data. For this study, we utilized simulated data to investigate the power of LCMs to detect the mean of the quadratic slope, Type I error rates, and rates of nonconvergence during the estimation of quadratic LCMs. Five factors were examined: the number of time points, growth magnitude, interindividual variability, sample size, and the R 2s of the measured variables. The results showed that the empirical Type I error rates were close to the nominal value of 5 %. The empirical power to detect the mean of the quadratic slope was affected by the simulation factors. Finally, a substantial proportion of samples failed to converge under conditions of no to small variation in the quadratic factor, small sample sizes, and small R 2 of the repeated measures. In general, we recommended that quadratic LCMs be based on samples of (a) at least 250 but ideally 400, when four measurement points are available; (b) at least 100 but ideally 150, when six measurement points are available; (c) at least 50 but ideally 100, when ten measurement points are available