Abstract 1944: A novel vasoactive intestinal peptide-grafted curcumin nanomedicine for targeting breast cancer stem cells

Abstract

Purpose: Despite recent advances in breast cancer therapy, many patients still experience relapse. Evidence suggests that a sub-population of treatment-resistant “cancer stem cells” (CSCs) may be responsible for recurrence of the disease. Recently, we have shown that nanotechnology-based delivery of curcumin in sterically stabilized phospholipid micelles (C-SSM) significantly improved the anti-cancer stem cell (anti-CSC) activity of free curcumin (C-DMSO) in a tumorsphere formation assay using MCF-7 human breast cancer cells (Gulcur et al. AAPS annual meeting, 2011). Here, we investigate 1) the expression of vasoactive intestinal peptide (VIP) receptors on MCF-7 CSCs, and 2) the efficacy of a novel VIP-grafted C-SSM formulation (C-SSM-VIP) to eliminate CSCs, with the aim of further improving the anti-CSC activity of C-SSM. Methods: VIP receptor expression of MCF-7 CSCs was determined using a fluorescence-based ligand binding assay. Cells, previously sorted into CD44+/CD24−/low CSC and CD44+/CD24+ normal cancer cell populations using flow cytometry, were cytospun to glass slides and stained with fluorescence-labeled VIP. Mean fluorescence intensities (MFIs) were quantified from confocal microscope images of the slides. The C-SSM nanomedicine and VIP conjugation to activated distearoyl phosphatidylethanolamine - polyethylene glycol 3400-NHS (VIP-DSPE-PEG) were prepared as previously described (Thaqi et al. CRS annual meeting, 2011; S. Dagar et al. J. Ctrl. Rel. (2001) 74:129-134). VIP-DSPE-PEG constructs were incorporated into C-SSM by incubation to form C-SSM-VIP. Anti-CSC activity of C-SSM-VIP was evaluated using a tumorsphere formation assay, where MCF-7 cells were seeded in ultralow attachment plates as a single cell suspension in serum-free media. C-DMSO, C-SSM and C-SSM-VIP at 5 μM curcumin concentrations, and control treatments were then added to the culture. Sphere formation was evaluated under microscope after 7 days. Results: Analysis of the MFIs from confocal images showed ∼3-fold higher expression of VIP receptors on the CSC population of MCF-7 cells compared to normal cancer cells (P<0.05). Furthermore, targeting the VIP receptors on CSCs with C-SSM-VIP had a significantly higher efficacy for inhibition of sphere formation compared to both C-SSM and C-DMSO (66.9% ± 2.7 vs. 58.9% ± 2.9 and 57.5% ± 4.3, respectively; P<0.05). Conclusion: These findings demonstrate for the first time that improved elimination of breast CSCs can be achieved with the C-SSM-VIP nanomedicine that employs a dual targeting strategy by 1) delivering curcumin in an effective way to target CSC pathways, and 2) actively targeting CSCs through internalizing VIP receptors. Therefore, we suggest that C-SSM-VIP should be further developed as a novel and safe nanomedicine with a high potential to provide a relapse-free cure of breast cancer. Funded by NIH grant CA121797. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1944. doi:1538-7445.AM2012-1944