Methioninase gene therapy with selenomethionine induces apoptosis in bcl-2-overproducing lung cancer cells.
We have previously shown that the toxic pro-oxidant methylselenol is released from selenomethionine (SeMET) by cancer cells transformed with the adenoviral methionine alpha,gamma-lyase (methioninase, MET) gene cloned from Pseudomonas putida. Methylselenol damaged the mitochondria via oxidative stress, and caused cytochrome c release into the cytosol thereby activating caspase enzymes and thereby apoptosis. However, gene therapy strategies are less effective if tumor cells overexpress the antiapoptotic mitochondrial protein bcl-2. In this study, we investigated whether rAdMET/SeMET was effective against bcl-2-overproducing A549 lung cancer cells. We established two clones of the human lung cancer A549 cell line that show moderate and high expression levels of bcl-2, respectively, compared to the parent cell line, which has very low bcl-2 expression. Staurosporine-induced apoptosis was inhibited in the bcl-2-overproducing clones as well as in the parental cell line. In contrast to staurosporine, apoptosis was induced in the bcl-2-overproducing clones as well as the parental cell line by AdMET/SeMET. Apoptosis in the rAdMET-SeMET-treated cells was determined by fragmentation of nuclei, and release of cytochrome c from mitochondria to the cytosol. A strong bystander effect of AdMET/SeMET was observed on A549 cells as well as the bcl-2-overproducing clones. rAdMET/SeMET prodrug gene therapy is therefore a promising novel strategy effective against bcl-2 overexpression, which has blocked other gene therapy strategies.
Yamamoto
Norio
N
AntiCancer, Inc., 7917 Ostrow Street, San Diego, CA 92111, USA. all@anticancer.com
Gupta
Anshu
A
Xu
Mingxu
M
Miki
Kenji
K
Tsujimoto
Yoshihide
Y
Tsuchiya
Hiroyuki
H
Tomita
Katsuro
K
Moossa
A R
AR
Hoffman
R M
RM
D017209:Apoptosis; D006690:Bisbenzimidazole / Q000494:pharmacology; D015153:Blotting, Western; D013437:Carbon-Sulfur Lyases / Q000235:genetics*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival; D004396:Coloring Agents / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D053938:DNA Fragmentation; D004797:Enzyme-Linked Immunosorbent Assay; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism* / Q000628:therapy*; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D016958:Pseudomonas putida / Q000235:genetics; D012645:Selenomethionine / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D014162:Transfection
D004396:Coloring Agents; D016877:Oxidants; D019253:Proto-Oncogene Proteins c-bcl-2; D013778:Tetrazolium Salts; D013844:Thiazoles; D045304:Cytochromes c; D012645:Selenomethionine; D013437:Carbon-Sulfur Lyases; C021558:L-methionine gamma-lyase; C022616:thiazolyl blue; D019311:Staurosporine; D006690:Bisbenzimidazole