Two-Wave Nanotherapy To Target the Stroma and Optimize Gemcitabine Delivery To a Human Pancreatic Cancer Model in Mice
ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) elicits a dense stromal response that blocks vascular access, because of pericyte coverage of vascular fenestrations. In this way, the PDAC stroma contributes to chemotherapy resistance in addition to causing other problems. In order to improve the delivery of gemcitabine, a first line chemotherapeutic agent, a PEGylated drug-carrying liposome was developed, using a transmembrane ammonium sulfate gradient to encapsulate the protonated drug up to 20% w/w. However, because the liposome was precluded from entering the xenograft site due to the stromal interference, we developed a first wave nanocarrier that decreases pericyte coverage of the vasculature through interference in the pericyte recruiting TGF-β signaling pathway. This was accomplished using a polyethyleneimine (PEI)/polyethylene glycol (PEG)-coated mesoporous silica nanoparticle (MSNP) for molecular complexation to a small molecule inhibitor, LY364947. LY364947 contains a nitrogen atom that attaches, through H-bonding, to PEI amines with a high rate of efficiency. The co-polymer coating also facilitates systemic biodistribution and retention at the tumor site. Because of the high loading capacity and pH dependent LY364947 release from the MSNPs, we achieved rapid entry of IV injected liposomes and MSNPs at the PDAC tumor site. This two-wave approach provided effective shrinkage of the tumor xenografts beyond 25 days, compared to the treatment with free drug or gemcitabine-loaded liposomes only. Not only does this approach overcome stromal resistance to drug delivery in PDAC, but also introduces the concept of using a step-wise engineered approach to address a range of biological impediments that interfere in nanocancer therapy in a spectrum of cancers.
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ABSTRACT: Pancreatic cancer exhibits the poorest prognosis among all tumors and is characterized by high resistance to the currently available chemotherapeutic agents. Our previous studies have suggested that stromal components could promote the chemoresistance of pancreatic cancer cells (PCCs). Here, we explored the roles of pancreatic stellate cells (PSCs) and the SDF-1α/CXCR4 axis in pancreatic cancer chemoresitance. Our results showed that primary PSCs typically expressed SDF-1α, whereas its receptor CXCR4 was highly expressed in PCCs. PSC-conditioned medium (PSC-CM) inhibited Gemcitabine (GEM)-induced cytotoxicity and apoptosis in the human PCC line Panc-1, which was antagonized by an SDF-1α neutralizing Ab. Recombinant human SDF-1α (rhSDF-1α) increased IL-6 expression and secretion in Panc-1 cells in a time and dose-dependent manner, and this effect was suppressed by the CXCR4 antagonist AMD3100. rhSDF-1α protected Panc-1 cells from GEM-induced apoptosis, and the protective effect was significantly reduced by blocking IL-6 using a neutralizing antibody. Moreover, rhSDF-1α increased FAK, ERK1/2, AKT and P38 phosphorylation in Panc-1 cells, and either FAK or ERK1/2 inhibition suppressed SDF-1α-upregulated IL-6 expression. SDF-1α-induced AKT activation was almost completely blocked by FAK inhibition. In conclusion, we demonstrate for the first time that PSCs promote the chemoresistance of PCCs to GEM, and this effect is mediated by paracrine SDF-1α/CXCR4 signaling-induced activation of the intracellular FAK-AKT and ERK1/2 signaling pathways and a subsequent IL-6 autocrine loop in PCCs. Our findings indicate that blocking the PSC-PCC interaction by inhibiting SDF-1α/CXCR4 signaling may be a promising therapeutic strategy for overcoming chemoresistance in pancreatic cancer.Oncotarget 12/2014; · 6.63 Impact Factor
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ABSTRACT: Recently, a commercial albumin-bound paclitaxel (PTX) nanocarrier (Abraxane®) was approved as the first new drug for pancreatic ductal adenocarcinoma in almost a decade. PTX improves the pharmaceutical efficacy of the first-line pancreatic cancer drug, gemcitabine (GEM), through suppression of the tumor stroma and inhibiting the expression of the GEM-inactivating enzyme, cytidine deaminase (CDA). We asked, therefore, whether it was possible to develop a mesoporous silica nanoparticle (MSNP) carrier for pancreatic cancer to co-deliver a synergistic GEM/PTX combination. High drug loading was achieved by a custom-designed coated lipid film technique to encapsulate a calculated dose of GEM (40 weight %) by using a supported lipid bilayer (LB). The uniform coating of the 65 nm nanoparticles by a lipid membrane allowed incorporation of a sub-lethal amount of hydrophobic PTX, which could be co-delivered with GEM in pancreatic cells and tumors. We demonstrate that ratiometric PTX incorporation and delivery by our LB-MSNP could suppress CDA expression, contemporaneous with induction of oxidative stress as the operating principle for PTX synergy. To demonstrate the in vivo efficacy, mice carrying subcutaneous PANC-1 xenografts received intravenous (IV) injection of PTX/GEM-loaded LB-MSNP. Drug co-delivery provided more effective tumor shrinkage than GEM loaded LB-MSNP, free GEM, or free GEM plus Abraxane®. Comparable tumor shrinkage required co-administration of 12 times the amount of free Abraxane®. HPLC analysis of tumor-associated GEM metabolites confirmed that, compared to free GEM, MSNP co-delivery increased the phosphorylated, DNA-interactive GEM metabolite 13-fold, while decreasing the inactivated, deaminated metabolite 4-fold. IV injection of MSNP-delivered PTX/GEM in a PANC-1 orthotopic model effectively inhibited primary tumor growth as well as eliminating metastatic foci. The enhanced in vivo efficacy of the dual delivery carrier could be achieved with no evidence of local or systemic toxicity. In summary, we demonstrate the development of an effective LB-MSNP nanocarrier for synergistic PTX/GEM delivery in pancreatic cancer.ACS Nano 03/2015; 9(4). DOI:10.1021/acsnano.5b00510 · 12.03 Impact Factor
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ABSTRACT: Pancreatic cancer is usually diagnosed at the advanced stages, responds poorly to the available chemotherapeutics and constitutes the major factor for high mortality rate. Selective delivery of therapeutics to their cellular targets, without side effects is the foremost objective of the current investigations for effective treatment of pancreatic cancer. The development of the drugs which can selectively target pancreatic cancer along with carriers that can deliver drugs specifically to the rapidly dividing cells is considered as magic bullet for the efficient treatment of this fatal disease. This review describes various factors hampering the efficacy of drug targeting to pancreatic cancer including stromal fortress, hypocascularity, hyaluronan and interstitial fluid pressure, and exploration of various cellular targets for the site specific drug delivery. An account of burgeoning applications of novel drug delivery systems including nanoparticles, liposomes, quantum dots, micelles and drug conjugates in the management of pancreatic cancer is also provided. Additionally, potential of target based therapeutic agents and nanomedicines in clinical trials for the pancreatic cancer therapy are highlighted.Journal of Biomedical Nanotechnology 12/2014; 10(12). DOI:10.1166/jbn.2014.2036 · 7.58 Impact Factor