Impaired brain clearance of amyloid-beta peptides (Aβ) 40 and 42 across the blood–brain barrier (BBB) is believed to be one of the pathways responsible for Alzheimer’s disease (AD) pathogenesis. Hyperinsulinemia prevalent in type II diabetes was shown to damage cerebral vasculature and increase Aβ accumulation in AD brain. However, there is no clarity on how aberrations in peripheral insulin levels affect Aβ accumulation in the brain. This study describes, for the first time, an intricate relation between plasma insulin and Aβ transport at the BBB. Upon peripheral insulin administration in wild-type mice: the plasma clearance of Aβ40 increased, but Aβ42 clearance reduced; the plasma-to-brain influx of Aβ40 increased, and that of Aβ42 reduced; and the clearance of intracerebrally injected Aβ40 decreased, whereas Aβ42 clearance increased. In hCMEC/D3 monolayers (in vitro BBB model) exposed to insulin, the luminal uptake and luminal-to-abluminal permeability of Aβ40 increased and that of Aβ42 reduced; the abluminal-to-luminal permeability of Aβ40 decreased, whereas Aβ42 permeability increased. Moreover, Aβ cellular trafficking machinery was altered. In summary, Aβ40 and Aβ42 demonstrated distinct distribution kinetics in plasma and brain compartments, and insulin differentially modulated their distribution. Cerebrovascular disease and metabolic disorders may disrupt this intricate homeostasis and aggravate AD pathology.
MicroRNAs are small (18-22 nucleotide long) noncoding RNAs that play important roles in biological processes through posttranscriptional regulation of gene expression. Their aberrant expression and functional significance are reported in several human malignancies, including pancreatic cancer. Recently, we identified miR-150 as a novel tumor suppressor microRNA in pancreatic cancer. Furthermore, expression of miR-150 was downregulated in the majority of tumor cases, suggesting that its restoration could serve as an effective approach for pancreatic cancer therapy. In the present study, we developed a nanoparticle-based miR-150 delivery system and tested its therapeutic efficacy in vitro. Using double emulsion solvent evaporation method, we developed a poly (D,L-lactide-co-glycolide) (PLGA)-based nanoformulation of miR-150 (miR-150-NF). Polyethyleneimine (a cationic polymer) was incorporated in PLGA matrix to increase the encapsulation of miR-150. Physical characterization of miR-150-NF demonstrated that these nanoparticles had high encapsulation efficiency (~78%) and exhibited sustained release profile. Treatment of pancreatic cancer cells with miR-150-NF led to efficient intracellular delivery of miR-150 mimics and caused significant downregulation of its target gene (MUC4) expression. Inhibition of MUC4 correlated with a concomitant decrease in the expression of its interacting partner, HER2, and repression of its downstream signaling. Furthermore, treatment of pancreatic cancer cells with miR-150-NF suppressed their growth, clonogenicity, motility, and invasion. Together, these findings suggest that PLGA-based nanoformulation could potentially serve as a safe and effective nanovector platform for miR-150 delivery to pancreatic tumor cells.
A critical barrier to improved cancer therapy is the recurrence of drug‐resistant tumors expanded from tumor‐initiating stem‐like cells (TICs). Discovery of a drug that specifically targets the TIC population is critical for effective treatment. We first performed drug screening on TICs for the identification of cell‐type specific drugs and found that all‐trans retinoic acid (ATRA) specifically inhibited cell viability. Additionally, transduction of human TICs with a lentivirus Nanog‐GFP reporter was used to perform high‐throughput screening for Nanog‐inhibitory drugs. HDAC inhibitor (SAHA), among several candidates, suppressed Nanog expression. Three high‐throughput screenings identified the best combination of repurposed FDA‐approved drugs (ATRA and SAHA). Moreover, combination of RA with SAHA synergistically reduced Nanog expression and inhibited the self‐renewal abilities of TICs resulting in apoptosis in vitro and in vivo. Genome‐wide transcriptome analysis by using of RNA‐seq showed that combined treatment reduced microRNA‐22, which induced phosphatase and tensin homolog (PTEN) and ten‐eleven translocation (TET). PTEN‐mediated FOXO activation promotes BIM‐mediated apoptosis. TET induction demethylates p53‐binding sites within the Nanog promoter proximal region. The drug combination epigenetically altered DNA methylation of Nanog promoter leading to inactivation of Nanog in TICs. Taken together, ATRA and SAHA may serve as a novel strategy for HCC treatment. Support or Funding Information This project was supported by NIH research grants R01AA018857, P50AA011999 (Southern California Research Center for ALPD and Cirrhosis, pilot project, program, animal core, morphology core), Lee‐Summer‐Project funding, P30DK048522 (USC Research Center for Liver Diseases, pilot project program), Non‐Parenchymal Liver Cell Core (R24AA012885) and UO‐021898. This research was also supported by a Research Scholar Grant (RSG‐12‐177‐01‐MPC); pilot funding from American Cancer Society (IRG‐58‐007‐48); The Cell and Tissue Imaging Core ‐ USC Research Center for Liver Diseases (P30 DK048522).
Recent studies suggest that apolipoprotein A-I (ApoA-I), the major protein constituent of high-density lipoprotein particles, plays a critical role in preserving cerebrovascular integrity and reducing Alzheimer's risk. ApoA-I present in brain is thought to be primarily derived from the peripheral circulation. Although plasma-to-brain delivery of ApoA-I is claimed to be handled by the blood-cerebrospinal fluid barrier (BCSFB), a contribution by the blood-brain barrier (BBB), which serves as a major portal for protein delivery to brain, cannot be ruled out. In this study, we assessed the permeability–surface area product (PS) of radioiodinated ApoA-I (125I-ApoA-I) in various brain regions of wild-type rats after an intravenous bolus injection. The PS value at the cortex, caudate putamen, hippocampus, thalamus, brain stem, and cerebellum was found to be 0.39, 0.28, 0.28, 0.36, 0.69, and 0.76 (ml/g per second × 10−6), respectively. Solutes delivered into brain via the BCSFB are expected to show greater accumulation in the thalamus due to its periventricular location. The modest permeability for 125I-ApoA-I into the thalamus relative to other regions suggests that BCSFB transport accounts for only a portion of total brain uptake and thus BBB transport cannot be ruled out. In addition, we show that Alexa Flour 647-labeled ApoA-I (AF647-ApoA-I) undergoes clathrin-independent and cholesterol-mediated endocytosis in transformed human cerebral microvascular endothelial cells (hCMEC/D3). Further, Z-series confocal images of the hCMEC/D3 monolayers and Western blot detection of intact ApoA-I on the abluminal side demonstrated AF647-ApoA-I transcytosis across the endothelium. These findings implicate the BBB as a significant portal for ApoA-I delivery into brain.
Abstract MicroRNAs (miRNAs) are small (18-22 nucleotide long) non-coding RNAs that play important roles in biological processes through post-transcriptional regulation of gene expression. Their aberrant expression and functional significance are reported in several human malignancies, including pancreatic cancer (PC). Recently, we identified miR-150 as a novel tumor suppressor microRNA in PC and demonstrated that its overexpression inhibits growth and malignant behavior of PC cells suggesting that restoration of miR-150 could serve as an effective therapeutic approach for pancreatic cancer. In the present study, we have developed a nanoparticle-based miR-150 delivery system and tested its therapeutic efficacy by in vitro assays. Using double emulsion solvent evaporation method, we developed a poly (D, L-lactide-co-glycolide) (PLGA)-based nanformulation (NF) of miR-150 (miR-150-NF). Polyethyleneimine (a cationic polymer) was incorporated in PLGA matrix to increase the encapsulation of miR-150. Physical characterization of miR-150-NF demonstrated that miR-150-loaded nanoparticles were spherical in shape, had high encapsulation efficiency (>75%), were stable at room temperature and exhibited sustained release profile. miR-150-NF efficiently delivered miR-150 mimics to PC cells and led to the downregulation of its target gene (MUC4) expression. Downregulation of MUC4 correlated with a concomitant decrease in the expression of its interacting partner, HER2, and repression of its downstream signaling. Furthermore, treatment of PC cells with miR-NF suppressed their growth, clonogenicity, motility and invasion. Together, these findings suggest that PLGA-based nanovector platform could be a potential candidate for systemic delivery of miR-150 to the pancreatic tumor cells and can be a step forward in miRNA-based cancer therapeutics. Citation Format: Sumit Arora, Suresh K. Swaminathan, Sanjeev K. Srivastava, Seema Singh, Jayanth Panyam, Ajay P. Singh. Development of miRNA-loaded polymeric nanoformulation for pancreatic cancer therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1457. doi:10.1158/1538-7445.AM2014-1457
