Liposome-Mediated Down-Regulation of Gastrin in Pancreatic Cancer Cells
Open Access
- Author:
- Fenn, Craig William
- Graduate Program:
- Cell and Molecular Biology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Jill P Smith, Thesis Advisor/Co-Advisor
Jill P Smith, Thesis Advisor/Co-Advisor - Keywords:
- siRNA
liposomes
pancreatic cancer
small interfering RNA - Abstract:
- Pancreatic cancer is among the most aggressive and lethal of all forms of cancer. Developing novel treatment strategies against pancreatic cancer can lead to increased survival time and increased chances for surgical removal of pancreatic tumors. Gastrin, a stomach hormone that is also produced by pancreatic cancer cells during the early stages of pancreatic cancer development, is a growth-stimulating factor that contributes to pancreatic cancer growth through binding to the cholecystokinin-2 receptor. Because of its growth-stimulating effects, gastrin is a potential target for therapeutic strategies. For that reason, lowering gastrin production could possibly also inhibit the growth of pancreatic cancer. To examine this possibility, we have developed a nanoliposome-based delivery system to deliver anti-gastrin siRNA to pancreatic cancer cells. These liposomes have been taken into various different pancreatic cancer cell lines in vitro and have also successfully encapsulated siRNA molecules targeting positions 90 and 286 of the gastrin mRNA. Liposome-encapsulated siRNAs have also been successfully transfected into the AsPC-1-Luc and BxPC-3-Luc cell lines, and have been able to down-regulate gastrin mRNA in both of these cell lines (determined via endpoint and quantitative real-time RTPCR analysis). SiRNA targeted to position 286 of the gastrin mRNA has also downregulated gastrin peptide via immunocytochemical analysis. SiRNA targeted to position 90 of the gastrin mRNA was then found to inhibit the growth of the BxPC-3-Luc cell line in vitro over a 10-day period. Finally, to determine the in vivo effectiveness of the liposome-mediated transfection system, liposome-encapsulated siRNAs against positions 90 and positions 286 of the gastrin mRNA were administered three times a week via intravenous injection into athymic nude mice containing orthotopic BxPC-3-Luc tumors. The liposome/siRNA mixtures were not toxic to the mice, but did not provide significant down-regulation of gastrin mRNA and did not significantly decrease tumor size. However, the results obtained suggest a trend toward the down-regulation of gastrin mRNA as well as the inhibition of tumor growth. We conclude that while the liposomemediated anti-gastrin siRNA delivery system we have developed has the potential for being an effective treatment strategy for pancreatic cancer, additional improvements to the system need to be made to increase transfection efficiency in vitro and in vivo.