Original ArticlesLiposomal insulin promoter–thymidine kinase gene therapy followed by ganciclovir effectively ablates human pancreatic cancer in mice
Introduction
Pancreatic cancer remains a terrible and challenging disease, representing only 2.8% of new cancers but ultimately responsible for 6.8% of all cancer deaths [1]. Pancreatic cancer has demonstrated remarkable resistance to conventional therapies. Only a quarter of patients with localized disease survive 5 years beyond diagnosis [1].
Pancreatic duodenal homeobox 1 (PDX1) is a gene specific to pancreatic tissue, is aberrantly expressed in pancreatic cancer, and facilitates oncogenesis [2], [3]. Taking advantage of PDX1-mediated stimulation of the insulin promoter, we previously developed a novel recombinant gene therapy that targets PDX1 expressing cells: a recombinant rat insulin promoter–viral thymidine kinase (IP-TK) gene [4]. Aberrant PDX1 expressed by pancreatic cancer cells would bind and activate the insulin promoter, driving the expression of viral thymidine kinase, sensitizing them to ganciclovir (GCV) [4], [5]. Previously, we demonstrated adenoviral IP-TK/GCV therapy ablates human pancreatic cancer in vitro and in vivo in SCID mice [4], [6], [7], [8], [9].
Adenoviral IP-TK/GCV therapy is limited by several factors. These include toxicity to healthy tissue, resulting in hyperglycemia with repeat dosing, as well as reduced efficacy of repeat doses due to induction of viral antigen targeting antibodies [8]. Even a single virus infusion will result in antibody development, which has led to myriad strategies to circumvent this therapeutic obstacle [10], [11], [12], [13]. Given that a number of studies have demonstrated successful gene delivery to cancer cells using non-viral liposomal vectors [14], [15], [16], we hypothesized that multiple cycles of liposomal naked IP-TK DNA followed by GCV can efficiently ablate human PDAC in mice with less toxicity and retain efficacy with repeat dosing.
Section snippets
Cell lines, plasmid vectors and antibodies
The human pancreatic cancer cell line PANC-1 was purchased from the American Type Culture Collection (ATCC, Bethesda, MD), and was maintained in DMEM medium (Invitrogen, MD) supplemented with 100,000 units/l of penicillin, 100,000 µg/l of streptomycin and 10% fetal bovine serum. Plasmid DNA IP-lacZ and IP-TK were constructed as described previously [7], [17]. Rabbit and goat anti-HSV-TK antibody were purchased from Santa Cruz Biotechnology Inc. (Santa Cruz, CA). Cy3 conjugated anti-rabbit IgG
Cytotoxicity of empty vector liposomal DNA
SCID mice that received 35 µg or less of liposomal empty vector plasmid DNA had a 100% survival rate at 26 days. Mice that received 40 µg of liposomal empty vector DNA had a 50% survival rate at 26 days, and doses 50 µg and higher resulted in 0% survival at 26 days.
Multiple doses of L-IP-TK/GCV reduce or ablate xenograft pancreatic tumor volume in mice
Four cycles of L-IP-TK/GCV, 10–35 µg, significantly reduced more PANC-1 tumor volume compared to a single cycle of 35 µg. Four cycles of 35 µg iv L-IP-TK/GCV resulted in the smallest remaining tumor volume among all treatment groups
Discussion
Multiple doses of liposomal IP-TK/GCV successfully ablated human pancreatic cancer in SCID mice and prolonged survival. The longest median survival was seen in a lower dose of L-IP-TK, 10 µg, with 50% of tumors completely ablated. Improved survival in the 10 µg group versus higher doses indicates toxicity, albeit minimal, and begins to outweigh the benefit of greater tumor-killing efficacy with higher doses. Tumor killing efficacy was maintained with repeated dosing and was more effective than
Conflict of interest
The authors declare that there is no conflict of interest.
Acknowledgement
We would like to thank Katie Elsbury for proof reading and editing this manuscript.
References (21)
- et al.
Enhanced cytotoxicity of RIPTK gene therapy of pancreatic cancer via PDX-1 co-delivery
J. Surg. Res
(2007) - et al.
Effective ablation of pancreatic cancer cells in SCID mice using systemic adenoviral RIP-TK/GCV gene therapy
J. Surg. Res
(2007) - et al.
Multiple treatment cycles of liposome-encapsulated adenoviral RIP-TK gene therapy effectively ablate human pancreatic cancer cells in SCID mice
Surgery
(2011) - et al.
Circumvention of vector-specific neutralizing antibody response by alternating use of human and non-human adenoviruses: implications in gene therapy
Virology
(2000) - et al.
Gene delivery to carcinoma cells via novel non-viral vectors: nanoparticle tracking analysis and suicide gene therapy
Eur. J. Pharm. Sci
(2014) - et al.
Gene silencing via RNAi and siRNA quantification in tumor tissue using MEND, a liposomal siRNA delivery system
Mol. Ther
(2013) - et al.
SEER Cancer Statistics Review, 1975–2011
(2014) - et al.
Tissue MicroArray analyses of pancreatic duodenal homeobox-1 in human cancers
World J. Surg
(2005) - et al.
Pancreatitis-diabetes-pancreatic cancer: summary of an NIDDK-NCI workshop
Pancreas
(2013) - et al.
Cell-specific cytotoxicity of human pancreatic adenocarcinoma cells using rat insulin promoter thymidine kinase-directed gene therapy
World J. Surg
(2004)
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