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Abstract 2162: Novel anti-gastrin nanoparticle inhibits growth of pancreatic cancer
Abstract Background: Receptor-targeted therapies or inhibition of growth factors have improved cancer survival. Pancreatic ductal adenocarcinoma (PDAC) markedly over-expresses the cholecystokinin-B (CCK-B) receptor and re-expression gastrin stimulates growth of PDAC by an autocrine mechanism through...
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| Published in: | Cancer research (Chicago, Ill.) Ill.), 2016-07, Vol.76 (14_Supplement), p.2162-2162 |
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| Main Authors: | , , , , , , |
| Format: | Article |
| Language: | English |
| Online Access: | Get full text |
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| Summary: | Abstract
Background: Receptor-targeted therapies or inhibition of growth factors have improved cancer survival. Pancreatic ductal adenocarcinoma (PDAC) markedly over-expresses the cholecystokinin-B (CCK-B) receptor and re-expression gastrin stimulates growth of PDAC by an autocrine mechanism through the CCK-B receptor. When gastrin mRNA is down regulated by RNAi techniques, PDAC growth and metastases are inhibited in animal models. However, anti-gastrin gene therapy cannot be readily used in humans unless nontoxic gene delivery strategies are implemented. The purpose of this project was to develop a unique drug delivery nanoparticle (NP) that selectively binds to the CCK-B receptor and safely delivers siRNA to down-regulate gastrin expression and inhibit growth of PDAC.
Methods: In order to develop the targeted NP, a thiol functionalized polyethylene glycol-block-poly(L-lysine) (SH-PEG-PLL) polymer was synthesized. To render the NP target-specific for the CCK-B receptor we used a maleimide link to conjugate Gastrin-10 to the PEG via Michael addition reaction. The resulting Ga-PEG-PLL was extensively purified using a PD-10 column and by dialysis. The polyplex micelle was prepared by mixing 1mg/mL of the Ga-PEG-b-PLL with a gastrin siRNA (si286 GUGCUGAGGAUGAGAACUA), which decreases gastrin mRNA 90%. The PEG protects the siRNA from degradation in solution or blood and the lysine polymer forms a micelle shielding the positive charge and eliminating toxicity. The NP was analyzed by dynamic light scattering (DLS) and zeta potential. Efficacy of the NPs to inhibit growth was tested on PANC-1 human PDAC cells that have a high number of CCK-B receptors. Cells were plated into 6-well plates overnight and then treated for 72h with PBS, 100x NP (10nM siRNA) or 50x NPs (5nM siRNA) in serum-free DMEM media. Viable cell counts were performed by trypan blue exclusion.
Results: Characterization of the functionalized polyplex NP confirmed a molecular weight of 9700 Da. Trityl deprotection and conjugation of Ga-10 to the SH-PEG-PLL polymer were confirmed by NMR which demonstrated complete removal of the trityl group and greater than 70% conjugation of the peptide to target the receptor. The polyplex NP complex was confirmed by DLS measurement, which demonstrated size distributions of 44.3 ± 0.3 and 48.2 ± 0.3 nm for receptor-targeted and untargeted polyplex respectively. Treatment of PANC-1 cancer cells with the anti-gastrin NPs significantly inhibited growth by 98% compared |
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| ISSN: | 0008-5472 1538-7445 |
| DOI: | 10.1158/1538-7445.AM2016-2162 |