Survival Efficacy of the Combination of the Methioninase Gene and Methioninase in a Lung Cancer Orthotopic Model

Cancer Gene Ther. 2000 Feb;7(2):332-8. doi: 10.1038/sj.cgt.7700103.

Abstract

We have previously demonstrated the antitumor efficacy of recombinant methioninase (rMETase) derived from Pseudomonas putida. To enhance the efficacy of rMETase, we have constructed the pLGFP-METSN retrovirus encoding the P. putida methioninase (MET) gene fused with the green fluorescent protein (GFP) gene. pLGFP-METSN or control vector pLGFPSN was introduced into the human lung cancer cell line H460. The methionine level of H460-GFP-MET cells was reduced to 33% of that of H460-GFP cells. rMETase (0.08 U/mL) in the medium resulted in 10% survival of H460-GFP-MET cells compared with untreated cells in vitro. In contrast, rMETase-treated H460-GFP cells survived at 90% of control. Tissue fragments harvested from subcutaneous tumors of H460-GFP-MET or H460-MET were implanted by surgical orthotopic implantation into the lungs of nude mice. A suboptimal dose of rMETase was administered intraperitoneally daily to mice in each group. Overall survival of rMETase-treated animals with H460-GFP-MET tumors was significantly longer than either rMETase-treated or -untreated animals with H460-GFP tumors (P < .05 in log-rank test). In two repeat experiments, rMETase-treated animals with H460-GFP-MET tumors had a 30-day survival of 80% and 83%, respectively. Untreated animals with H460-GFP-MET tumors had a 30-day survival of 40% and 58%, respectively. rMETase-treated animals with H460-GFP tumors had a 30-day survival of 0% and 33%, respectively. Untreated animals with H460-GFP tumors had a 30-day survival of 0% and 33%, respectively. The retrovirus-mediated gene transfer of METase decreased the intracellular methionine level of tumor cells and consequently enhanced the efficacy of treatment with the rMETase protein. We have thus demonstrated a new strategy of combination tumor therapy with the gene and gene product of MET.

MeSH terms

  • Animals
  • Antimetabolites, Antineoplastic / therapeutic use*
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • Carbon-Sulfur Lyases / genetics*
  • Carbon-Sulfur Lyases / metabolism
  • Female
  • Genetic Vectors / genetics
  • Green Fluorescent Proteins
  • Humans
  • Luminescent Proteins / genetics
  • Lung Neoplasms / enzymology
  • Lung Neoplasms / genetics*
  • Lung Neoplasms / mortality
  • Lung Neoplasms / therapy*
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • Neoplasm Transplantation
  • Retroviridae / genetics
  • Survival Rate
  • Transfection
  • Tumor Cells, Cultured

Substances

  • Antimetabolites, Antineoplastic
  • Luminescent Proteins
  • Green Fluorescent Proteins
  • Carbon-Sulfur Lyases
  • L-methionine gamma-lyase