Effective ablation of pancreatic cancer cells in SCID mice using systemic adenoviral RIP-TK/GCV gene therapy.
BACKGROUND
Studies have demonstrated that adenovirus subtype 5 mediated rat insulin promoter directed thymidine kinase (A-5-RIP-TK)/ganciclovir (GCV) gene therapy resulted in significant enhanced cytotoxicity to both PANC-1 and MIA PaCa2 pancreatic cancer cells in vitro. However, little is known about the effect in vivo. In this study we examine the in vivo safety and efficacy of intravenous A-5-RIP-TK/GCV gene therapy.


METHODS
1 x 10(6) Mia PaCa2 cells were injected intraperitoneally (i.p.) into SCID mice to create a mouse model of human pancreatic cancer. A-5-RIP-TK gene construct was administered intravenously (i.v.), followed by i.p. GCV administration. Intravenous injection of A-5-RIP-lacZ reporter gene constructs was used for evaluation of Ad-RIP-gene expression in tumors and other tissues. Optimal adenoviral and GCV doses and treatment duration were determined. Tumor volume, serum insulin, and glucose levels were measured. Immunohistochemical staining of pancreata and tumors were performed to assess morphology and hormone expression and apoptotic rates were determined.


RESULTS
All A-5-RIP-TK/GCV-treated mice had reduced tumor volume compared with controls, but maximal tumor volume reduction was observed with 10(8) vp followed by GCV treatment for 4 wk. A-5-RIP-TK/GCV gene therapy contributed to significant survival advantage in MIA PaCa2 bearing mice, and the greatest survival benefit was observed with 10(8) vp and was not affected by length of treatment of GCV. A-5-RIP-TK/GCV therapy increased PDX-1 expression and tumor cells apoptosis, and altered islet morphology. However, A-5-RIP-TK/GCV gene therapy caused diabetes associated with islet cell apoptosis, increased delta-cells and reduced pancreatic polypeptide (PP)-cell numbers.


CONCLUSIONS
Systemically administered A-5-RIP-TK/GCV is an effective treatment of pancreatic cancer. A-5-RIP-TK/GCV cytotoxicity to malignant cells varies with adenoviral dose and length of GCV treatment. However, A-5-RIP-TK/GCV is associated with islet cell toxicity and diabetogenesis. The type of diabetes observed is distinct from Types 1 and 2 and is associated with islet cell apoptosis and reduced delta- and PP-cells.
Liu
Shi-He
SH
Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas 77030, USA.
Davis
Alan
A
Li
Zhijun
Z
Ballian
Nikiforos
N
Davis
Elizabeth
E
Wang
Xiao-Ping
XP
Fisher
William
W
Brunicardi
F Charles
FC
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D000998:Antiviral Agents / Q000627:therapeutic use*; D017209:Apoptosis; D045744:Cell Line, Tumor; D003920:Diabetes Mellitus / Q000209:etiology; D004305:Dose-Response Relationship, Drug; D015774:Ganciclovir / Q000627:therapeutic use*; D015972:Gene Expression Regulation, Neoplastic; D015316:Genetic Therapy / Q000009:adverse effects / Q000379:methods*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007274:Injections, Intraperitoneal; D007515:Islets of Langerhans / Q000473:pathology; D008297:Male; D051379:Mice; D016513:Mice, SCID; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000628:therapy*; D013937:Thymidine Kinase / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
D000998:Antiviral Agents; D018398:Homeodomain Proteins; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D013937:Thymidine Kinase; D015774:Ganciclovir