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J Thorac Cardiovasc Surg. 2003 Jun;125(6):1328-35.

Adenoviral melanoma differentiation-associated gene 7 induces apoptosis in lung cancer cells through mitochondrial permeability transition-independent cytochrome c release.

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Section of Thoracic Molecular Oncology, Department of Thoracic and Cardiovascular Surgery, The University of Texas M.D. Anderson Cancer Center, and Introgen Therapeutics Inc, Houston, TX 77030, USA.



Melanoma differentiation-associated gene 7 is a novel tumor suppressor gene that induces apoptosis in lung cancer cells when delivered by adenoviral gene transfer as Ad-mda7. The mechanisms of action are not well defined but may involve release of cytochrome c from the mitochondria with subsequent caspase activation.


The lung cancer cell lines A549 and H1299 were transduced with Ad-mda7, adenovirus containing the gene for p53 (Ad-p53), and control adenoviral luciferase vectors. Staurosporine was used as a positive control to induce cytochrome c release through mitochondrial permeability transition-dependent pores, whereas cyclosporine (INN: ciclosporin) was used to specifically inhibit these mitochondrial permeability transition-dependent pores. Apoptosis was evaluated with fluorescence-activated cell sorting analysis of subdiploid populations and mitochondrial membrane potential changes with tetramethylrhodamine ethylester perchlorate.


Melanoma differentiation-associated gene 7, transduced by Ad-mda7 into H1299 and A549 lung cancer cells, resulted in sharp increases in cytosolic cytochrome c levels followed by induction of apoptosis and cellular death. The release of cytochrome c from the mitochondria occurred without changes in the mitochondrial membrane potential. Unlike staurosporine treatment, transduction with Ad-p53 and Ad-mda7 caused releases of cytochrome c and apoptosis that were not blocked by cyclosporine, suggesting a mitochondrial permeability transition pore-independent pathway.


Ad-mda7 induces apoptosis in lung cancer cells through mitochondrial cytochrome c release in a process that is not dependent on mitochondrial membrane potential changes and occurs through mitochondrial permeability transition-independent pores. This unique mechanism of action may allow treatment of patients with lung cancer resistant to mitochondrial permeability transition-dependent cell death processes.

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