Abstract 4469: An evaluation of the role of mucin in nano drug delivery
Authors: Alkholief Musaed A. , Campbell Robert 
Published: May 2015

Introduction: Solid tumors comprise more than 85% of cancers that affect humans. The presence of the extracellular matrix, namely mucin, on the tumor cell is considered one of the barriers against effective treatment of solid tumors. In tumor cells, mucin is aberrantly overexpressed producing a mucin mesh which may impede the rate of entry of chemotherapy medications. The type O-glycosylation inhibitor, benzyl-α-GalNAc, significantly reduces mucin type O-glycosylation in mucin-producing tumor cells resulting in enhanced cytotoxic drug action. We next seek to determine the role of mucin in the delivery of nano-sized drug delivery systems.

Methods: The cell lines used were derived from tumor or normal tissues representing multiple organ environments. These cell lines include: Capan-1, Capan-2, PANC-1, HPAF-II (human adenocarcinoma), hTERT-HPNE (normal human pancreas), CRL-1777 (normal murine pancreas), ZR-75-1 (breast cancer), and CRL-2089 (normal breast). Evaluation of MUC1 protein expression was done by western blot analysis in addition to fluorescence microplate reader using CD227 (anti-MUC1 antibody). Furthermore, we investigated the cellular uptake of the fluorescently labeled polystyrene microsphere beads and liposomes in the different cell lines. Finally, FACS analysis was used to determine cellular uptake following inhibition of mucin type O-glycosylation and compared to control.

Results: Different levels of mucin expression were observed among the various cell lines. By investigating the antibody association with the MUC1 protein core, Capan-1and ZR-75-1have shown the greatest cellular uptake following inhibition of glycosylation. To evaluate the cellular uptake of the microsphere beads and liposomes we used cell lines derived from the pancreas. The glycosylation inhibitor had little to no effect on the uptake of the microsphere beads, regardless of cell line employed. However, the overall uptake of the large beads (990 nm) was significantly greater in comparison to the uptake of the smaller beads (67 and 116 nm). Next, we carried out the same procedure using liposomes that were made in the size range of 60-80nm, 100-120nm, and 350-550nm. Out of the 6 pancreatic cell lines examined, PANC-1 cell line showed that the uptake of each liposome preparation type was significantly greater following the inhibition of mucin glycosylation. In addition, we observed that the uptake of liposomes increased as a function of liposome size. This was confirmed by FACS analysis as well.

Conclusion: Our results suggest that inhibiting the mucin type O- glycosylation alters the uptake of the microsphere beads in all the cell lines examined. As for the liposomes, however, the effect of inhibiting glycosylation is cell line dependent. Further studies will be performed to investigate the factors underlying the differential uptake observed with liposomes following inhibition of glycosylation. This might be helpful in developing a better nano-therapeutic approach to treat cancer.

Citation Format: Musaed A. Alkholief, Robert Campbell. An evaluation of the role of mucin in nano drug delivery. [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 4469. doi:10.1158/1538-7445.AM2014-4469