Survival efficacy of the combination of the methioninase gene and methioninase in a lung cancer orthotopic model

• Published in: Cancer gene therapy Vol. 7; no. 2; pp. 332 - 338
• Main Authors: Miki, K, Xu, M, An, Z, Wang, X, Yang, M, Al-Refaie, W, Sun, X, Baranov, E, Tan, Y, Chishima, T, Shimada, H, Moossa, A R, Hoffman, R M
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.02.2000
• Subjects: Animals; Antimetabolites, Antineoplastic - therapeutic use; Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Antitumor activity; Carbon-Sulfur Lyases - genetics; Carbon-Sulfur Lyases - metabolism; Female; Gene transfer; Genetic Vectors - genetics; Green fluorescent protein; Green Fluorescent Proteins; H460 cells; Humans; Luminescent Proteins - genetics; Lung cancer; Lung Neoplasms - enzymology; Lung Neoplasms - genetics; Lung Neoplasms - mortality; Lung Neoplasms - therapy; Male; Methionine; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Transplantation; Retroviridae - genetics; Retrovirus; Survival Rate; Transfection; Tumor cells; Tumor Cells, Cultured; Tumors
• ISSN: 0929-1903; 1476-5500
• DOI: 10.1038/sj.cgt.7700103

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.