The immunosuppressive effect of rapamycin is mediated by inhibition of interleukin-2-stimulated T cell proliferation. We report for the first time that rapamycin also inhibits growth factor-induced proliferation of cultured mouse proximal tubular (MPT; IC(50) ~1 ng/ml) cells and promotes apoptosis of these cells by impairing the survival effects of the same growth factors. On the basis of these in vitro data, we tested the hypothesis that rapamycin would impair recovery of renal function after ischemic acute renal failure induced in vivo by renal artery occlusion (RAO). Rats given daily injections of rapamycin or vehicle were subjected to RAO or sham surgery. Rapamycin had no effect on the glomerular filtration rate (GFR) of sham-operated animals. In rats subjected to RAO, GFR fell to comparable levels 1 day later in vehicle- and rapamycin-treated rats (0.25 +/- 0.08 and 0.12 +/- 0.05 ml. min(-1). 300 g(-1), respectively) (P = not significant). In vehicle-treated rats subjected to RAO, GFR increased to 0.61 +/- 0.08 ml. min(-1). 300 g(-1) on day 3 (P < 0.02 vs. day 1) and then rose further to 0.99 +/- 0.09 ml. min(-1). 300 g(-1) on day 4 (P < 0.02 vs. day 3). By contrast, GFR did not improve in rapamycin-treated rats subjected to RAO over the same time period. Rapamycin also increased apoptosis of tubular cells while markedly reducing their proliferative response after RAO. Furthermore, rapamycin inhibited activation of 70-kDa S6 protein kinase (p70(S6k)) in cultured MPT cells as well as in the renal tissue of rats subjected to RAO. We conclude that rapamycin severely impairs the recovery of renal function after ischemia-reperfusion injury. This effect appears to be due to the combined effects of increased tubular cell loss (via apoptosis) and profound inhibition of the regenerative response of tubular cells. These effects are likely mediated by inhibition of p70(S6k).
2950 Poster Board II-926 Background: Multiple studies in closely related diseases such as Chronic Lymphocytic Leukemia (CLL) have revealed distinct miRNA profiles. This increasing appreciation for the role of miRNA expression in disease pathogenesis and homeostasis within cancer biology lead us to profile the miRNA expression of CD19+ bone marrow cells from 11 patients with Waldenstrom's Macroglobulinemia (MR) and 5 healthy donors. The median age for patients was 72 years (range 49-81), WM ISS Prognostic Score was 1 (range 0-4), bone marrow disease involvement was 40% (range 5-80%), and serum IgM was 3,330 (range 202-6,110 mg/dL). Five patients (45.5%) were previously treated and 4 (36.4%) had extramedullary disease. Patients and Methods: CD19+ cells were selected using auto-MACs cell sorting (Miltayni Biotec) and total RNA was extracted with Trizol (Invitrogen). Micro-RNA profiling was conducted using TaqMan low density arrays (Applied Biosystems) allowing for stem-loop based qPCR detection of 670 miRNAs per sample. Results were validated using RT2 miRNA SYBR green based qPCR (SABiosciences). Relative quantification was calculated by ddCT using U6 endogenous controls and normalized to the first healthy donor sample. Results were analyzed using custom perl scripts running bootstrap calculated 95% CIs and approximate permutation testing from 10,000 resampling groups for both means and medians resulting in a robust and distribution independent characterization of each population. Additional Mann-Whitney-Wilcoxon, general linear modeling (GLM), ANOVA, and Spearman correlation testing was conducted using R (R Project for Statistical Computing). Results: We identified miR-29c (+3.2 fold), miR-339-5p (+2.0 fold), and miR-21 (+3.2 fold) as significantly up-regulated in WM patients (p<0.006 for all). Down-regulated miRNAs included miR-324-3p (-2.0 fold), miR 875-5p (-3.2 fold) and miR-638 (-7.2 fold) (p<0.006 for all). Analysis of these findings with clinical features revealed a positive correlation of miR-29c with serum IgM (rho=.65, p=0.03), using multivariate analysis that included age and previous treatment status (p<0.001). Both miR-875-5p and miR324-3p inversely correlated with bone marrow disease involvement (rho <-0.79, p<0.005 for both), and both of these were found to be predictive under multivariate analysis (p < 0.001 and < 0.01 respectively). Furthermore, mir-638 was found to correlate with the presence of extramedullary disease (p=0.026). As some miRNAs are known to destroy their target mRNAs, we compared our findings to our existing gene expression profiling data using the Sanger miRBase Target Database. miR-29c was predicted to target MAD2L1BP (AKA p31comet, CTM2), a tumor senescence inducing protein whose expression is down-regulated in WM by gene expression profiling (-2.1 fold, p<0.0001); in addition, miR-21 which is predicted to target IL-12A was also decreased by -2.0 fold by gene expression profiling (p=0.005). Conclusions: The above findings demonstrate a distinct miRNA profile in WM, and implicate several miRNAs in the pathogenesis of WM, including genes involved in the regulation of tumor cell senescence and IL-12A. These findings provide a framework for the exploration of novel signaling pathways and therapeutic approaches in WM. Disclosures: No relevant conflicts of interest to declare.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.