Combined suicide gene therapy for pancreatic peritoneal carcinomatosis using BGTC liposomes

Abstract

Peritoneal dissemination is a common end-stage complication of pancreatic cancer for which novel therapeutic modalities are actively investigated, as there is no current effective therapy. Thus, we evaluated, in a mouse model of pancreatic peritoneal carcinomatosis, the therapeutic potential of a novel nonviral gene therapy approach consisting of bis-guanidinium-tren-cholesterol (BGTC)-mediated lipofection of a combined suicide gene system. Human BxPC-3 pancreatic cells secreting the carcinoembryonic antigen (CEA) tumor marker were injected into the peritoneal cavity of nude mice. After 8 days, intraperitoneal (i.p.) lipofection was performed using BGTC/DOPE cationic liposomes complexed with plasmids encoding the two prodrug-activating enzymes Herpes Simplex Virus thymidine kinase and Escherichia coli cytosine deaminase, the latter being expressed from a bicistronic cassette also encoding E. coli uracil phosphoribosyltransferase. Administration of the lipoplexes was followed by treatment with the corresponding prodrugs ganciclovir and 5-fluorocytosine. The results presented herein demonstrate that BGTC/DOPE liposomes can efficiently mediate gene transfection into peritoneal tumor nodules. Indeed, HSV-TK mRNA was detected in tumor nodule tissues by semiquantitative reverse transcription-polymerase chain reaction analysis. In addition, green fluorescent protein (GFP) fluorescence and X-gal staining were observed in the peritoneal tumor foci following lipofection of the corresponding EGFP and LacZ reporter genes. These expression analyses also showed that transgene expression lasted for about 2 weeks and was preferential for the tumor nodules, this tumor preference being in good agreement with the absence of obvious treatment-related toxicity. Most importantly, mice receiving the full treatment scheme (BGTC liposomes, suicide genes and prodrugs) had significantly lower serum CEA levels than those of the various control groups, a finding indicating that peritoneal carcinomatosis progression was strongly reduced in these mice. In conclusion, our results demonstrate the therapeutic efficiency of BGTC-mediated i.p. lipofection of a combined suicide gene system in a mouse peritoneal carcinomatosis model and suggest that BGTC-based prodrug-activating gene therapy approaches may constitute a potential treatment modality for patients with peritoneal carcinomatosis and minimal residual disease.

Gene-Directed Enzyme Prodrug Cancer Therapy

“…The latter approach is also known as gene-directed enzyme prodrug therapy (GDEPT) and is basically a two-step process. First, the enzymecoding gene is selectively delivered to tumors followed by the systemic or intratumoral administration of a prodrug in a subtherapeutic dose [8,9]. The accumulation of the prodrug's toxic metabolites then causes target-specific death in the enzyme-bearing cells or the surrounding cells ( Figure 6.1).…”

Heat-induced transcription of diphtheria toxin A or its variants, CRM176 and CRM197: implications for pancreatic cancer gene therapy

“…[3][4][5][6] However, the efficacy of gene therapy, designed to correct inherited or acquired genetic defects and/or confer new genetic and phenotypic characteristics to cells, 3,4,7 is limited in the treatment of PC. 3,4,[8][9][10][11][12][13][14] Immunotoxins, bacteria or plant-derived protein toxins vehicled by molecules bind target antigens or receptors to the cell surface, 5,6,[15][16][17] the most widely used products being diphtheria toxin (DT) and pseudomonas exotoxin, which arrest cytosolic protein synthesis by modifying the elongation factor 2.…”

Gene therapy for hepatocellular carcinoma using sonoporation enhanced by contrast agents

“…29,30 Currently, some studies have reported that commercially available transfection reagents (i.e., Lipoplexes) have proved useful for nonviral gene therapy. [31][32][33][34][35] We too are very interested in these reagents. Nevertheless, we expect that targeted gene therapy by sonoporation using contrast agents for HCC would be a much easier method, based on our experience using contrast agents to detect hepatic tumors by US examination in clinical situations.…”