Specific gene expression and therapy for pancreatic cancer using the cytosine deaminase gene directed by the rat insulin promoter

J Gastrointest Surg. 2004 Jan;8(1):98-108; discussion 106-8. doi: 10.1016/j.gassur.2003.10.008.


Suicide gene therapy has been shown to be an effective means of destroying pancreatic cancer cells, but cell-specific delivery of the gene is required to limit host toxicity. The objective of this study is to determine whether the rat insulin promoter (RIP) will permit cell-specific gene delivery and subsequent cell death in human pancreatic cancer cells. The RIP DNA was amplified using polymerase chain reaction (PCR), and the purified fragment was inserted into pCR-Blunt II-TOPO plasmid at the SpeI site, which contains the coding sequence of yeast cytosine deaminase (CD). Transfection assays were carried out using both RIP-lacZ and RIP-CD DNA constructs in two human pancreatic cancer cell lines, PANC-1 and MIA PaCa-2. Reporter assays using X-gal staining were performed, and the in vitro cytotoxicity was examined in RIP-CD-transfected cells treated with 5-flucytosine for 5 days. The expression levels of CD protein in the transfected cells were determined 2 days after transfection by Western blot analysis. The expression levels of insulin promoter factor (IPF-1/PDX-1) in these human pancreatic cell lines, as well as in freshly isolated human pancreatic cancer specimens, were determined using in situ immunohistochemistry analysis. After transfection with RIP-lacZ, only PANC-1 cells, but not MIA PaCa-2 cells, were positive for RIP-lacZ expression, indicating that RIP-directed reporter gene expression occurred only in PANC-1 cells. After transfection with RIP-CD and treatment with 5-flucytosine, PANC-1 cells had a significantly increased cell death rate compared with that of MIA PaCa-2 cells, suggesting that RIP-directed suicide gene expression occurred only in PANC-1 cells. Western blot analysis demonstrated that only PANC-1 cells were able to express the CD protein and that significantly increased levels of PDX-1 were found in PANC-1 but not in Mia PaCa-2 cells. In situ immunohistochemical analysis of both cell lines showed that PDX-1 was only expressed in the nuclei of PANC-1 cells and not in MIA PaCa-2 cells. Furthermore, two freshly isolated human pancreatic cancer specimens had significantly increased levels of PDX-1. The RIP is activated in PANC-1 cells, but not in Mia PaCa-2 cells, and the mechanism of activation is via PDX-1. Pancreatic cancer-specific cytotoxicity can be achieved with the use of RIP-CD and 5-flucytosine treatment in vitro. Significantly increased levels of PDX-1 have been found in human pancreatic cancer specimens. These results suggest that RIP could be used for cell-specific suicide gene therapy to target human pancreatic tumors.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antimetabolites / therapeutic use
  • Blotting, Western
  • Cytosine Deaminase / genetics*
  • Flucytosine / therapeutic use
  • Genes, Transgenic, Suicide*
  • Genetic Therapy
  • Homeodomain Proteins / metabolism
  • Humans
  • Lac Operon
  • Pancreatic Neoplasms / therapy*
  • Trans-Activators / metabolism
  • Transcription Factors
  • Transfection
  • Tumor Cells, Cultured


  • Antimetabolites
  • Homeodomain Proteins
  • Trans-Activators
  • Transcription Factors
  • pancreatic and duodenal homeobox 1 protein
  • Flucytosine
  • Cytosine Deaminase